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Explore CNC Meaning & CNC Technology

GreatLight’s blog aims to share our hard-earned knowledge on Explore CNC Meaning & CNC Technology. We hope these articles help you to optimize your product design and better understand the world of rapid prototyping. Enjoy!

CNC Knowledge: What is tempering?

Great Light CNC Machining Services 29/12/2024 23:53

On television, you may have seen a blacksmith dipping a red-hot sword in water or oil. This is called “extinction” (don’t feel bad if you think it’s called “extinction”, it’s a common mistake). Quenching is an ancient method of rearranging the atomic structure of a material.

Quenching is the process of rapidly cooling a material, usually a metal, to achieve desirable mechanical properties such as increased strength and hardness.

Most people think of quenching as simply immersing hot steel in a bucket of water, but materials scientists can quench it in water, oil, liquid nitrogen, and even air . Quenching is an important processing step for many materials. Quenching can refine grains or manipulate phase transitions. A very important phase transition is that from martensite to austenite in steel, which I will discuss in depth later.

To determine the effect of quenching on a metal, materials scientists can use tests or time-temperature-transition (TTT) curves.

We’ll come back to these technical terms later, but first let’s look at all the cool things you can do with tempering.

In this article, we will focus on the following points to learn how to “quench” with each one:

1. What is the purpose of quenching?

2.What is the history of tempering?

3. What is a quenching medium?

4. What happens when steel is quenched?

5. What are the characteristics of the martensitic transformation?

6. What are the main characteristics of martensite?

7. What is retained austenite?

8. How does carbon content affect the hardness of quenched steel?

9. What are the stages of quenching?

10. How fast do we need to quench to get martensite (what is a TTT curve)?

11. Final Thoughts

1. What is the purpose of quenching?

When most people think of quenching, they probably imagine a blacksmith placing a piece of red-hot steel into a bucket of water. The spectrum of quenching is much broader than that, but let’s start with this example and explore what quenching can do in steel.

The first thing quenching can do is refine the grain.

If you didn’t know, metals are crystals. Unlike the crystals you usually think of, like gemstones, metals are “polycrystalline.” This means that the metal is made up of many small crystals. We call each of these little crystals a “particle.”

It turns out that repeating patterns are a very stable way for atoms to organize themselves. The three most common crystal structures are body-centered cubic (BCC), face-centered cubic (FCC), and hexagonal close-packed (HCP).

The way atoms are arranged can have a huge impact on the properties of materials – just look at diamond and graphite! Much of materials science affects the properties of materials by changing the crystal structure.

When a layman talks about crystals, they are usually referring to precious stones: diamonds, rubies, sapphires or salt. This is a particular type of crystal: a single crystal. A single crystal has an unbroken pattern of atoms throughout the material.

Most often, materials such as metals are polycrystalline. These materials still have a repeating structure, but this structure is broken down into different grains.

When a phase solidifies, it starts with just a few atoms. These atoms come together and grow. All atoms joining this group will have the same orientation and will form a particle. At some point, one grain will collide with another.

If the phase solidifies more slowly, there will be fewer initial grains and each grain will be larger. If the phase solidifies more quickly, there will be many initial grains, each smaller.

Generally speaking, smaller grains mean a stronger, less ductile metal. I hope I’ve illustrated this with my homemade animation, but if you want to look it up yourself, it’s called the Hall-Page effect.

Now, in my explanation, I may be implying something incorrect. This pattern of grain nucleation and growth looks very interesting when you create a solid phase from a liquid, but it is not typical quenching.

For example: In steel, quenching takes us from one solid phase to another. This still results in grain refinement, but it also has larger implications.

Steel begins in a phase called “ferrite”. When you heat steel, it transitions to a new phase called “austenite.” Austenite can dissolve more carbon than ferrite, which is a good thing. If you cool the austenite you will get ferrite again – provided you cool the steel slowly enough to give the carbon time to leave the metal.

On the other hand, if you cool the steel quickly, you obtain a new phase: “martensite”. Martensite is very hard and has a lot of pressure. Martensite is essentially ferrite with too much carbon inside. so we call it the new martensite phase.

Twisted crystals are very hard but brittle. Swords, knives and other tools are made from martensitic steel for high strength.

But if you look at a phase diagram, you won’t see martensite. Martensite is not a thermodynamically stable phase, but you can still get it in the final product. The graph that tells you about austenite is called a time-temperature transformation graph, or TTT curve. We will discuss TTT charts later.

So we learned that quenching can make the grains smaller and create a more stressed phase. These two effects make the steel stronger but less ductile.

In some cases, quenching can make the material more ductile and flexible. In the case of most steels, you will see that the quenching rate results in metastable martensite and not ferrite, which is thermodynamically favorable.

However, in other materials (or certain particular steels), quenching makes it possible to avoid the strengthening or weakening phase.

When it comes to superalloys, nickel-based superalloys have a very good phase called gamma’ (pronounced “gamma-primeˮ). This is the thermodynamically stable phase, but there are other “bad” phases called TCP. Technically, these make the superalloy stronger, but they also make it more brittle/less ductile.

Typically, materials scientists refine strength (the force a material can withstand) and ductility (the amount of deformation a material can withstand). TCP is slightly stronger but more fragile, so in 99% of applications, γ’ is better than TCP.

When you make an alloy at high temperatures, if you cool it slowly, TCPs can form. They are generally stable at temperatures above γ’. Unfortunately, once the superalloy is cold enough, where γ’ is more stable than TCP, diffusion will be quite slow and TCP will last indefinitely.

However, if the superalloy is quenched, this temperature range is ignored, in which TCP is stable and only γ’ is obtained.

Tempering is also used for thermal tempering of glass. Yes, the term is strange because we usually use the word “temper” to refer to the weakening of a metal after tempering, but thermal tempering is a method of making glass stronger.

2. What is the history of tempering?

Quenching existed long before scientists knew how it worked. Don’t feel bad if you don’t know how to quench your thirst either! Old blacksmiths and blacksmiths learned techniques through trial and error and held their skills closely. Some legends claim that great blacksmiths would dip their swords into the bodies of slaves (actually this might work, or at least blood might sometimes be better than water, see section on means of extinction below) .

Tempering a sword creates enormous pressure on the sword. Often, imperfect swords break. Different quenching methods or media can be used to reduce the risk of steel fracture, but until recently this level of metallurgy was shrouded in mysticism.

Perhaps the first written mention of extinction is in Homer’s The Odyssey. Blacksmiths place an ax or ax head in cold water to quench it – as this is what gives iron its strength. Quenching has been an important aspect of swordsmanship for centuries, but Japanese swordsmiths have perhaps the most sophisticated quenching techniques.

Japanese swords are made by gradual hardening. They coated the blade with clay so that the back of the sword hardened more slowly, giving it a stronger ferrite. The edge of the sword is made of pure and hard martensite, while the core of the sword is stronger and more malleable.

3. What is a quenching medium?

As you will learn in the TTT curve section below, different quench rates will produce different results. Different metals can survive different quenching without cracking.

In some steels you may want a different ratio of martensite to ferrite. Of course, non-steel metals behave very differently from steel and require their own quenching methods. Most of the time, quenching simply depends on how quickly the material is cooled.

Often the only way to control the rate of cooling is to use a quenching agent (i.e., the elements contained in the barrel). Theoretically you can change the temperature of the quenching medium, but you already have hot metal, so a few degrees change in water temperature doesn’t matter. On the other hand, differences in specific heat or boiling point can cause large differences in cooling rates.

The most common quenching fluids are water, brine (brine), oil, liquid nitrogen and air. Each of these media has different advantages and disadvantages.

01water

Water is one of the most common quenching fluids because it is readily available and allows for rapid quenching. Water is nonflammable and has a high specific heat and heat of vaporization. So when the water boils, it quickly cools the material. However, the bubbles produced by boiling reduce thermal conductivity, ultimately resulting in slower quenching. (This layer of insulation caused by the bubbles is called the Leidenfrost effect).

02 salt water

Brine is just water with salt added. It has many of the same benefits as water, but salt increases the boiling point of water, which reduces boiling bubbles and speeds up quenching. A disadvantage of brine quenching is that the salt can sometimes corrode or otherwise react with certain alloys.

The Legend About Quenching Swords in Blood: Since blood is also water with dissolved electrolytes (salts), blood is similar to weak salt water from a quenching standpoint (although urine looks more like salt water). Blood also contains large amounts of organic compounds that can clot and adhere to the slide, reducing the Leidenfrost effect. It’s also possible that these carbon molecules react to form small amounts of carbides on the surface, although I doubt this will be noticeable. In short, quenching in blood may produce different/more ideal quenching than that in water.

03 oil

There are several types of oils, but they all have lower specific heats than water, resulting in slower quenching rates. I’ve seen amateur knife makers use machine oil, vegetable oil, peanut oil – even recycled frying oil from some students’ favorite fried chicken restaurants!

Oil is a good medium speed quenching agent and can help prevent cracking. A disadvantage of oil quenching is that the oil surface can catch fire. Therefore, great care must be taken when oil quenching.

04 liquid nitrogen

Liquid nitrogen actually goes out more slowly than water because nitrogen becomes a gas (lower thermal conductivity) and has a lower heat capacity and heat of vaporization. However, liquid nitrogen ultimately results in a colder final quench than other media, which is necessary in some steel alloys. For example, many stainless steels precipitate martensite at very low temperatures that water cannot reach.

05 aerial

Typically, air quenching is accomplished by blowing cold air onto the sample very quickly. Air quenching is often used in industrial settings because air is very cheap and by controlling the speed of the air in different parts of the product you can achieve different quench rates in different locations. Air quenching is generally the slowest way of quenching.

Another type of air quenching simply allows the part to cool in still air. I generally call this “air quenched” rather than air quenched, but some alloys can achieve a quenched microstructure even at very slow cooling rates – in which case this term “air quenched” is appropriate .

4. What happens when steel is quenched?

This is the phase diagram of steel. The x-axis shows the percentage of carbon and the y-axis shows the temperature.

When quenching steel, we must first heat it above the austenitizing temperature. In hypoeutectoid steel (to the left of the eutectic point), the steel will have an austenitic phase. In hypereutectoid steel (to the right of the eutectic point), the steel will have two phases: austenite and cementite.

In order to obtain martensite, the steel must change phase during quenching. Below the austenitizing temperature, nothing happens during quenching. Austenite is the face-centered cubic (FCC) form of iron, usually denoted by γ, and can dissolve more carbon atoms than the face-centered cubic (BCC) form of ferrite (denoted α). Austenite can dissolve 2% of carbon, while ferrite can dissolve 0.025% of carbon. This is due to the size and number of interstitial sites in the FCC and BCC structures.

When we quench the steel, it cools quickly and hopefully transforms from BCC austenite to FCC ferrite. However, the cooling rate is too fast for the carbon atoms to move away, so they are essentially trapped in the FCC stage.

FCC iron containing carbon is no longer called ferrite: it is now martensite!

Martensite is a supersaturated solution of carbon that twists the body-centered cubic lattice into a body-centered tetragonal lattice. Depending on the steel composition and quenching rate, the final product may also contain retained ferrite or austenite.

5. What are the characteristics of the martensitic transformation?

These types of phase changes do not involve diffusion. All the atoms are moving in the same direction at the same time. Martensite often forms structures that resemble plates or needles. These are called slats.

When martensite forms, it creates internal stresses in the steel. These constraints inhibit other phase transformations. Remember that a phase diagram actually has 3 axes: composition, temperature and pressure. In most materials science phase diagrams, we only represent composition and temperature, because we assume that the pressure is simply atmospheric pressure, but that internal stresses act in the same way as external pressures.

The newly formed maretnist exerts compressive stress on the remaining austenite. This is what causes “retained austenite”. There is almost always some retained austenite, so 100% steel will never become pure martensite.

Austenite is denser than martensite so the volume increases after quenching (this is why Japanese swords are curved: there is more martensite on the edge, so one part of the blade expands more than the others , which gives a curved appearance).

Large steel parts can even crack during quenching due to internal stresses caused by the volume expansion of martensite. This phenomenon is a particularly serious problem if the carbon content is greater than 0.5% by weight.

If the steel is quenched too slowly to obtain martensite, you will obtain bainite or pearlite. Bainite occurs when carbon atoms are able to partially diffuse out of the crystal lattice. Once complete diffusion is achieved, perlite appears.

6. What are the main characteristics of martensite?

Martensite is the end product of conventional steel quenching. It is a supersaturated solid solution of carbon in a body-centered tetragonal (BCT) crystal structure. A BCT is essentially just a BCC but elongated in one direction. Martensite is a BCT because the carbon atoms are in the interstitial sites, but because the carbon atoms are larger than regular BCC interstitial sites, the lattice must be twisted.

Martensite is a metastable phase, meaning it cannot be predicted thermodynamically and does not appear on any phase diagrams. Another name for metastable phases is nonequilibrium structures. Given enough time, martensite will eventually break down, but this takes thousands of years at room temperature.

However, if the martensite is heated, the iron and carbon atoms will gain enough energy to increase the diffusion rate, thereby causing the atoms to reorganize into the more stable ferrite phase.

Martensite is very hard and brittle. In fact, quenched martensite is too brittle to be used in most engineering applications. Typically, steel is tempered after quenching. Quenching is a process in which steel is reheated (below the austenitizing temperature) and cooled slowly to reduce some internal stresses.

7. What is retained austenite?

Retained austenite is actually a stable (sometimes metastable) state at room temperature, however, it does not appear on a phase diagram because conventional phase diagrams assume standard atmospheric pressure.

Austenite becomes more likely as pressure increases due to internal stresses caused by volume expansion of martensite. You can see the phase diagram above, for pure iron, which shows that increasing pressure prefers austenite. With the addition of carbon, austenite is also stable at lower temperatures. If the austenite remains stable until room temperature (depending on the composition of the steel), it will be an equilibrium phase. However, even though retained austenite is stable at high pressures and hundreds of degrees Celsius, in many cases the low rate of diffusion at lower temperatures will allow metastable retained austenite to persist indefinitely.

Generally, retained austenite is an undesirable microstructural feature because it is much softer than martensite. As the carbon content increases, austenite retention becomes increasingly likely.

A simple way to test for the presence of retained austenite/martensite is to use X-ray diffraction (XRD). Since martensite is BCT and austenite is FCC, their different lattice parameters are easily displayed on XRD. The integration of the curve can even provide quantitative values for the fractions of martensite and austenite retained.

8. How does carbon content affect the hardness of quenched steel?

Generally speaking, more carbon makes steel harder and more brittle. However, more carbon also results in more retained austenite. Additionally, changes in carbon percentage alter the shape of the martensite laths and increase microcracks.

Beyond a certain point, adding carbon weakens the steel, because in unalloyed carbon steel the maximum hardness quenched in salt water is about 1% carbon.

9. What are the stages of quenching?

For reference, here is the relevant part of the iron-carbon phase diagram.

First, the alloy is heated to 30-50°C above the critical temperature. This area is shown in the image above. We don’t want to stay at this temperature for too long as it could cause the grains to grow.

If you are working with an alloy sensitive to oxidation, you may want to heat the alloy under vacuum. Some furnaces can heat under vacuum, but a simpler (small scale) method is to encapsulate the alloy in a quartz tube that has been evacuated or filled with an inert gas such as argon.

The alloy must be cooled quickly. The main way to control the cooling rate is to use different quenching media. Brine is generally the quickest practical way of quenching. Liquid nitrogen is a relatively slow quenching medium due to its low thermal conductivity and low specific heat.

If the alloy cools too quickly, it may crack. If it cools too slowly, you may not get many metastable phases. The best way to determine the optimal quench rate for a material is to use a Time-Temperature-Transition (TTT) chart.

10.What is the TTT curve?

A time-temperature transformation (TTT) plot is a diagram that shows which phases (including metastable phases) will be present at a specific cooling rate.

Temperature is displayed on the y-axis and time is displayed on the x-axis. Different stages occur, usually with a feature called a “nose.”

The lower horizontal line represents the time of martensite precipitation. If you dip fast enough to miss the nose (red line), you won’t precipitate any phases other than martensite. If you quench slower, as shown in the blue line, you get other phases like ferrite and cementite (we call the mixture of ferrite and cementite “pearlite”.

The purple line represents the minimum quench rate required to precipitate only martensite. In this case, that means quenching to 500°C in 5 seconds. Higher quenching rates have no effect on the fraction of phases present, but faster quenching can result in excessive internal stresses and cracking.

If the steel is not quenched quickly enough, this can result in the formation of bainite or pearlite (these are not necessarily bad phases: they are weaker but stronger than martensite).

11. Final Thoughts

Quenching is one of the most important tools for engineering alloys, especially steel. Quenching is accomplished by heating the metal and rapidly cooling it in a quenching medium such as water or oil.

Proper quenching allows precise control of the final microstructure and phases present in the alloy.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: What is an edge grinder?

Great Light CNC Machining Services 29/12/2024 22:52

The ‌rib grinder‌ is a special grinder, mainly used for grinding the ribs of bearings.

This grinder is designed and built to meet the precise machining requirements of bearing ribs in specific industrial applications. The key components of a rib grinder include the base plate, main support and auxiliary support.

The base plate is installed on the edge grinder, and the main support member is slidably provided on the base plate in the up and down direction and is connected to the base plate through the first locking structure.

The auxiliary support member is slidably provided on the base plate along an arc-shaped trajectory, and is connected to the base plate via the second locking structure. This design allows the bearing to be stably loaded on the rotating motor, and the bearing is supported by adjusting the positions of the main support and the auxiliary support.

The overall structure of the rib grinder includes a fuselage and a rotating motor. Using this grinder can achieve precise grinding of the bearing ribs and improve the performance and life of the bearing.

Famous flank grinder manufacturers, such as Kemeteng Company, Rifa Company, etc., business telephone number: 15910974236

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: What do you know about machine tool compensation?

Great Light CNC Machining Services 29/12/2024 21:51

Systematic mechanical deviations of machine tools can be recorded by the system, but due to environmental factors such as temperature or mechanical load, deviations may still appear or increase during subsequent use. In these cases, SINUMERIK can offer different compensation functions. Use measurements obtained with real position encoders (e.g. gratings) or additional sensors (e.g. laser interferometers, etc.) to compensate for deviations and achieve better machining results. In this issue you will learn about common SINUMERIK compensation functions. Practical SINUMERIK measuring cycles such as “MOTION MEASUREMENT CYCLE996” can provide comprehensive support to end users during the continuous monitoring and maintenance of machine tools.

game compensation

There will be interruptions or delays in the transmission of force between the moving parts of the machine tool and its driving parts, such as ball screws, because a mechanical structure without gaps will significantly increase the wear of the machine tool , and it is also difficult to achieve technologically. Mechanical backlash causes deviations between the motion path of the axis/spindle and the measured values of the indirect measuring system. This means that once the direction is changed, the axis will move too far or too close, depending on the size of the deviation. The workbench and its associated encoder are also affected: if the position of the encoder is ahead of the workbench, the latter reaches the command position earlier, which means that the distance actually traveled by the machine tool is reduced. During machine operation, using the backlash compensation function on the corresponding axis, the previously recorded deviation will be automatically activated when reversing direction, superimposing the previously recorded deviation on the actual position value .

Lead screw pitch error compensation

The principle of indirect measurement in CNC control systems is based on the assumption that the pitch of the ball screw remains unchanged during the effective stroke. Therefore, in theory, the actual position of the linear axis can be inferred based on the motion information. of the drive motor.

However, errors in ball screw manufacturing can lead to deviations in the measuring system (also called screw pitch errors). This problem can be further aggravated by measurement deviations (depending on the measurement system used) and installation errors of the measurement system on the machine tool (also called measurement system errors). In order to compensate for these two errors, an independent measuring system (laser measurement) can be used to measure the natural error curve of the CNC machine tool, and then the required compensation value is recorded in the CNC system for compensation.

Friction compensation (quadrant error compensation) and dynamic friction compensation

Quadrant error compensation (also called friction compensation) is suitable for all of the above situations to significantly increase contour accuracy when machining round contours. Here’s why: During a quadrant transition, one axis moves at maximum feedrate, while the other axis remains stationary. Therefore, the different friction behavior of the two axes can lead to contour errors. Quadrant error compensation can effectively reduce this error and ensure excellent machining results. The density of the compensation pulses can be set according to an acceleration-dependent characteristic curve, which can be determined and parameterized by a rounding test. During the roundness test, the difference between the actual position of the circular contour and the programmed radius (especially during inversion) is recorded quantitatively and displayed graphically on the man-machine interface.

In the new version of the system software, the built-in dynamic friction compensation function can dynamically compensate according to the friction behavior of the machine tool at different speeds, reduce the actual machining contour error, and achieve control precision higher.

Compensation for sag and angle errors

If the weight of certain machine parts causes the moving parts to shift and tilt, sag compensation is necessary as this can cause the affected machine parts, including the guide system, to sag. Angle error compensation is used when the movable axes are not aligned with each other at the correct angle (e.g. vertically). As the zero point position offset increases, the position error also increases. Both errors are caused by the self-weight of the machine tool or the weight of the tool and workpiece. The compensation values measured during debugging are quantified and stored in SINUMERIK in a form, for example a compensation table, depending on the corresponding position. When the machine tool is in operation, the positions of the axes concerned are interpolated according to the stored point compensation values. For each continuous movement, there are base and compensation axes.

temperature compensation

Heat can cause parts of the machine tool to expand. The expansion range depends on temperature, thermal conductivity, etc. of each part of the machine tool. Different temperatures can cause changes in the actual position of each axis, which can negatively impact the accuracy of the part being processed. These actual value changes can be compensated for by temperature compensation. The error curves of each axis at different temperatures can be defined. In order to always correctly compensate for thermal expansion, temperature compensation values, reference position and linear gradient angle parameters must be continuously transmitted from the PLC to the CNC control system via function blocks. Unexpected changes in parameters are automatically eliminated by the control system, thus avoiding machine overload and activating monitoring functions.

Spatial Error Compensation System (VCS)

Errors in the position of rotary axes, their mutual compensation and tool orientation can lead to systematic geometric errors in components such as rotary heads and orientation heads. In addition, small errors will occur in the feed axis guiding system of each machine tool. For linear axes, these errors are linear position errors; errors in horizontal and vertical straightness and for the axes of rotation, errors in pitch, yaw and roll angle; Other errors can occur when aligning machine tool components with each other. For example, vertical error. In a three-axis machine tool, this means that 21 geometric errors can occur on the tool tip: six types of errors per linear axis multiplied by three axes, plus three angular errors. These deviations work together to form a total error, also called spatial error.

Spatial error describes the deviation of the tool center point position (TCP) of an actual machine tool from that of an ideal, error-free machine tool. SINUMERIK solution partners can determine spatial errors using laser measuring devices. Measuring the error in one place is not enough; all machine tool errors in the entire machining space must be measured. It is usually necessary to record the measured values at all positions and plot them as a curve, because the size of each error depends on the position of the relevant feed axis and the measurement position. For example, when the y and z axes are at different positions, the resulting deviation on the x axis will be different: errors will occur even at almost the same position on the x axis. With “CYCLE996 – Motion Measurement” you can determine rotary axis errors in just a few minutes. This means that the precision of the machine tool can be constantly checked and, if necessary, corrected, even during production.

Deviation compensation (dynamic feedforward control)

Deviation refers to the deviation of the position controller from the standard when the machine axis is moving. Axis deviation is the difference between the target position of the machine tool axis and its actual position. Deviations cause unnecessary speed-related contour errors, especially when the contour curvature changes, such as circular, square, etc. contours. Thanks to the advanced NC language instruction FFWON in the part program, speed-related deviations can be reduced to zero when moving along the path. Improve path accuracy with feedforward control to achieve better processing results.

FFWON: command to start anticipatory control

FFWOF: command to deactivate anticipatory control

Electronic weight compensation

In extreme cases, to prevent the axis from sagging and damaging the machine, tool or workpiece, the electronic counterweight function can be activated. In loaded axles without mechanical or hydraulic counterweights, the vertical axle may collapse unexpectedly once the brake is released. Unexpected shaft sag can be compensated for when the electronic counterweight is activated. After releasing the brake, the position of the collapsed shaft is maintained by a constant balancing torque.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: Application of linear encoder in high precision machining of machine tools

Great Light CNC Machining Services 29/12/2024 20:49

Production efficiency and machining precision are important competitive factors in the machine tool industry. However, rapid changes in machine tool processing conditions pose challenges to improve production efficiency and processing precision. When processing parts, small batch production should be carried out with high economic efficiency and high precision. In the aerospace industry, high material removal capabilities are required for roughing, while high precision is required for finishing. When processing high-quality molds, large quantities of material must be removed during roughing and high surface quality is required during finishing. At the same time, if it is necessary to achieve the minimum spacing of processing paths within a certain processing time, the machine tool must have a sufficiently high processing feed rate.

Figure 1 The heating situation of the ball screw during multiple reciprocating movements at a feed speed of 10m/min, 25℃ (purple) ~ 40℃ (yellow)

The thermal stability of machine tools plays an increasingly important role in the rapid changes of their processing conditions. In particular, small batch production faces the challenge of constantly changing processing tasks and inaccessible thermal stability conditions. Constant changes in drilling, roughing and finishing operations also subject machine tool temperature conditions to changing conditions. When roughing, the cutting rate increases to over 80%, while when finishing, it is less than 10%. Increasing cutting speeds and feeds cause linear drive ball screws to heat up. Therefore, the position detection technology of the feed drive plays a very critical role in the thermal stability of machine tools.

Avoiding part size deviations due to machine tool heat is a topic that the machine tool industry faces. Active cooling, symmetrical machine tool structures and temperature measurement technology are widely used.

The temperature change of the machine tool is mainly caused by the ball screw of the feed axis. The temperature distribution along the ball screw is closely related to the feed speed and driving force. On machine tools that do not use linear encoders, changes in screw length due to temperature can cause serious defects in the part. In principle, a ball screw and a rotary encoder installed on the screw can be used for NC feed axis position detection, or a linear array ruler can be used for detection.

If the carriage position is detected using a screw thread and a rotary encoder, the ball screw must perform two tasks. As a drive system, it must transmit a large driving force, but as a measuring device, it is hoped that it can provide high precision position values and repeatable step values, but it does not There is only one rotary encoder on the position control ring. . Since wear or temperature changes in the drive mechanism cannot be compensated for, this structure is called semi-closed loop control. There are unavoidable positioning errors in the driving system, which seriously affect the quality of the workpiece.

Figure 2 Semi-closed loop position feedback control

Figure 3 Fully closed loop position feedback control

If a linear encoder is used to sense the carriage position, the position control loop includes the entire feed mechanism, which is why it is also called fully closed loop control. Then the backlash and transmission error of the machine tool drive components no longer affects the position detection accuracy, and its accuracy almost solely depends on the accuracy of the linear scale and position of the machine tool. ‘facility. The basic situation of linear axes and rotary axes is the same. Position detection is carried out via a motor rotary encoder installed on the reduction housing or a higher precision angle encoder directly connected to the rotary axis. If an angle encoder is used, higher accuracy and repeatability can be achieved.

In the aerospace industry, integrated components have the advantage of ensuring optimal use of materials with minimum weight. The material removal rate of monolithic components is approximately 95% or more, and high-speed cutting (HSC) machine tools require high-speed feeds and cutting. The high material removal rate of monolithic components has exceptional economic advantages, but it also causes the ball screw to generate a large amount of friction heat. The wear and thermal expansion of the ball screw also differ during the machining process, such as the feed in case of roughing and finishing. If the feeding drive adopts a semi-closed loop control mode (without linear encoder), the size of the processed parts will be different when producing small batches and short delivery times. Due to thermal expansion, tolerance requirements may not be met. If a linear encoder is used, these errors can be avoided and the thermal expansion of the ball screw can be completely compensated in a fully closed loop.

Figure 4 The impact of driving precision on small batch part processing

In order to achieve a high surface finish of the part, sometimes very detailed structures must be machined and the processing of blow molds or die casting molds takes a long time. Many molds are now processed directly by milling, without resorting to the tedious EDM process, and the diameter of the cutter used is even only 0.12 mm. The mold milling process not only requires high precision shapes, but also requires large feeds to reduce processing time, including for high hardness materials. Typical mold processing times range from 10 minutes to several days, but dimensional accuracy cannot be sacrificed due to the rapid processing speed. The paths of the first and last cut must be exactly the same to ensure that the time saved by increasing the feed is not wasted and that repair machining is avoided. The heating of the ball screw driven by the feed axis depends on the feed speed of each axis controlled by the NC program. The length variation of the ball screw can reach 150 μm/m. These conditions make semi-closed loop control mode impossible. to ensure dimensional accuracy. The typical heat generated by a ball screw results in a 20 μm edge over a 150 mm length of the mold. Errors caused by thermal expansion of the ball screw can make defects too large to repair in about half of the molds.

To successfully complete machining commands, machine tools must have high thermal stability. Even with different loads, machining accuracy must be maintained so that required tolerance levels are maintained throughout the entire stroke, including when cutting speeds and forces vary significantly. Thermal expansion of ballscrews driven by linear feed axes seriously affects accuracy and is affected by changes in speed and magnitude of load. If the carriage position is measured only by the screw thread and the rotary encoder, the positioning error can reach 100 μm in 20 minutes. Since this method cannot compensate for these basic steering errors within the control loop, it is called a semi-closed loop control system. The operating mode of the power drive using a linear scale is a fully closed-loop control system, which measures the error of the ball screw and compensates it in the fully closed-loop control. Replacing rotary encoders with angle encoders has similar benefits because mechanical transmission components also experience thermal expansion. Linear encoders and angle encoders provide the basis for ensuring the precision of machined parts, even under the demanding and constantly changing operating conditions of machine tools.

The linear encoder that provides position feedback signals is an indispensable requirement for high positioning accuracy of machine tools. It directly collects the actual position information of the feed axis. Mechanical connection parts have no influence on the position measurement results. Motion errors, thermal distortion errors and position errors are all detected by the linear encoder and included in the control loop. Therefore, it can eliminate the following potential error sources: positioning errors caused by the thermal properties of the ball screw; reversal errors caused by deformation of the drive mechanism caused by mechanical forces; movement errors caused by ball screw pitch errors.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

How to solve the vibration problem when processing CNC forming grinding equipment?

Great Light CNC Machining Services 29/12/2024 20:29

As a modern precision processing equipment, the processing efficiency and precision of CNC forming grinding machine are directly related to product quality and production efficiency. However, vibration issues have always been a problem for many manufacturers when processing. Vibration not only affects machining accuracy, but also can damage machine tools and reduce production efficiency. Therefore, it is particularly important to solve the vibration problem when processing CNC forming grinders.

There are many reasons for CNC forming grinding machine vibration, including mechanical vibration and electromagnetic vibration. Mechanical vibrations can arise from defects in the structure of the machine tool itself, such as wear or loosening of guide rails, screws, bearings and other components, as well as impact forces during operation. treatment. Electromagnetic vibrations are mainly caused by electromagnetic force when the motor is running.

In response to mechanical vibration, we can take the following measures: First, regularly maintain and inspect machine tools to ensure that key components such as guide rails, screws and bearings are firmly installed, well lubricated and free from damage. no obvious wear or loosening. Second, use vibration isolation measures, such as adding shock absorber pads or rubber isolators between key machine tool components to reduce vibration transmission. Finally, according to the processing needs and performance of the machine tool, the operating parameters of the machine tool, such as feed speed, cutting depth, etc., are reasonably adjusted to reduce the force impact and vibration during the processing process.

For electromagnetic vibration, we can start from the following aspects: First, select a suitable motor and make sure it is fixed and tightened to reduce vibration. Second, optimize electrical parameters, such as motor current and voltage adjustment, to optimize electromagnetic field distribution and reduce electromagnetic vibration. Finally, use electromagnetic protection measures around the motor, such as the use of metal shields or conductive paint, to reduce electromagnetic interference and vibration.

In addition, improving the manufacturing precision and assembly of machine tools is also an important method to reduce vibration. By using advanced manufacturing technologies, such as precision machining, precision assembly, etc., errors and vibrations of the machine tool itself can be reduced. At the same time, the accuracy of the machine tool is checked and adjusted regularly to ensure that the geometric accuracy and positioning accuracy of the machine tool are within the allowable range.

In summary, solving the vibration problem when processing CNC forming grinding machines requires starting from many aspects, including optimizing the mechanical structure, adjusting the electrical parameters and improving the precision of the machine- tool. Only by comprehensively considering various factors and taking effective measures can we ensure that the CNC forming grinding machine maintains stability during processing and improves processing precision and production efficiency.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: Top secret! It turns out that splines are treated like this

Great Light CNC Machining Services 29/12/2024 19:48

Complex and strong splined shafts play a key role in modern machinery, ensuring smooth power transmission and rotational precision. Whether you are an engineer, manufacturer, or someone interested in these mechanical marvels, you need to have a thorough understanding of the intricacies of splined shafts, their benefits, the know-how behind them, and their countless applications to get the most out of them . them.

1What is a splined shaft?

Splined shafts are specialized mechanical components essential for various mechanical and automotive systems. These shafts are characterized by their unique ridges (called splines) and can have internal or external splines.

Their design allows them to seamlessly engage with the corresponding grooves of the mating parts, ensuring a secure connection. This locking mechanism is essential for efficient torque transmission and precise rotational alignment. Splined shafts improve system performance and durability by preventing slippage and ensuring even load distribution.

Their adaptability and precision make them the first choice for industries that require safe and efficient power transmission.

Functions as an anti-rotation device The splined shaft acts as an anti-rotation device, fitting into the grooves of the mating part. This connection ensures torque transfer without misalignment, promoting synchronized operation and optimal system functionality.

Torque Transmission and Angle Matching These shafts play a vital role in transmitting torque and power. Their design ensures precise angular alignment, allowing components to work in harmony, increasing system efficiency and minimizing wear.

2 Advantages of splined shafts over other alternative shafts

Torque transmitting splined shafts can transmit higher torques than ordinary shafts. Interlocking splines provide a larger contact area, ensuring efficient power transfer.

Precisely aligned mesh splines and grooves ensure that the shaft and its mating components maintain precise rotational alignment, reducing the risk of misalignment and subsequent wear.

Anti-rotation feature The splined shaft design prevents unwanted relative rotation between interconnected parts, ensuring synchronized movement and function.

Durability Due to the even distribution of load on the splines, these shafts tend to last longer and are less subject to wear than regular or keyed shafts.

Compact Design Spline connections are generally more compact than other alternatives, allowing for a more elegant mechanical design and efficient use of space.

Reduce Slippage The interlocking nature of the splines ensures minimal slippage, even under high torque conditions, for consistent performance.

Easy assembly and disassembly Spline shafts can be easily connected or disconnected from their corresponding components, making maintenance and replacement of components easier.

3 Main Materials Used in Making Spline Shafts

Stainless Steel and Its Benefits Stainless steel is commonly used in the manufacturing of splined shafts and is known for its corrosion resistance and strength. This material guarantees durability even in harsh environments, making the splined shaft more reliable. Stainless steel’s non-reactivity and excellent wear resistance make it the first choice for durable and efficient splined shafts.

Carbon Steel and Its Unique Properties Carbon steel is the material of choice for manufacturing splined shafts due to its strength and ductility. Its combination of durability and workability makes it an ideal material for complex spline designs. The cost effectiveness and strength of carbon steel make it the first choice for many industrial and automotive applications.

Alloy Steel and Its Functions Chromium and molybdenum are added to alloy steel and are used in splined shaft structures for their enhanced properties. Alloy steel has higher strength and wear resistance and can withstand harsh conditions better than standard steel. The versatility and adaptability of alloy steel makes it the first choice for high-performance splined shafts.

Aluminum Alloys and Their Advantages Aluminum alloys are light but strong and can be used to make splined shafts for applications where weight reduction is required. These alloys offer good corrosion resistance and a high strength-to-weight ratio, ensuring durability without compromising performance. Their malleability allows them to design complex flutes and can therefore be used in a wide range of industries.

Bronze, the other material used in splined shafts, is favored for its wear resistance and is ideal where lubrication is unstable. Meanwhile, brass (a copper-zinc alloy) was chosen as the material for the splined shaft due to its machinability and anti-corrosion properties.

Where corrosion resistance and reduced torque are essential, lightweight materials such as nylon and other plastics are favored, with the added benefit of quiet operation.

Titanium has an excellent strength-to-weight ratio and plays an important role in weight-sensitive industries such as aerospace. Ceramics are suitable for niche applications requiring wear resistance, heat resistance and electrical insulation.

Finally, Teflon-based shafts stand out in scenarios where low friction and low chemical resistance are required.

4Practical applications of splined shafts

01Automotive Industry Description: Spline shafts are an integral part of various automotive systems, ensuring smooth power transmission and precise alignment. Example: In automobiles, splined shafts are often used in the transmission. They connect the transmission to the driveshaft, allowing efficient transfer of power from the engine to the wheels. Steering columns typically use a splined shaft to provide a secure connection between the steering wheel and the steering mechanism. 02Description of the aeronautical industry: In aerospace, splined shafts play a key role in propellers and rotors. Example: In helicopters, the main rotor shaft usually has splines that mesh with corresponding grooves in the rotor hub. This connection ensures that engine power is transmitted efficiently to the rotor blades, allowing for controlled and stable flight. 03Industrial machines Description: Splined shafts are found everywhere in manufacturing units and contribute to the proper functioning of various machines. Example: In conveyor systems, splined shafts connect the motors to the conveyor belts, ensuring synchronized movement. This ensures that items move smoothly through the production line without any hiccups or delays. 04 Agricultural Equipment Description: Agricultural machinery often uses splined shafts to perform power transmission and rotation tasks. Example: Tractors use splined shafts in their power take-off (PTO) systems. PTO shafts transfer power from the tractor to implements such as lawn mowers or combine harvesters, allowing them to operate efficiently. 05 Marine Application Description: In marine environments, splined shafts are used in propulsion systems and other machinery. Example: On boats, the propeller shaft is generally splined at the outlet of the engine. This ensures that the engine’s power is transferred directly to the propeller, propelling the boat forward. 06 Power Tool Description: Many handheld and stationary power tools use splined shafts to transmit torque and connect the tool. Example: Electric drills often have a splined shaft that connects the motor to the chuck. This design ensures that the rotational power of the motor is efficiently transmitted to the drill bit, enabling efficient drilling.

5 Care and maintenance of the splined shaft

01 Cleaning Tips to Extend Life Splined shafts are essential for power transmission in various machines and require regular maintenance to ensure optimal life and performance. Regular inspections can detect signs of wear or damage, paving the way for rapid intervention. Cleaning is crucial, regularly using a soft brush or compressed air to remove dirt and debris. Mild solvents or detergents are effective for deep cleaning, especially when contaminants such as grease and oil have built up. After cleaning, drying is essential to prevent corrosion, and materials prone to rust may benefit from rust inhibitors.

02The Importance and Best Practices of Lubrication Lubrication plays a key role in the maintenance of splined shafts. The choice of lubricant should be consistent with the shaft material and its application. Establishing a consistent lubrication routine minimizes friction and wear, ensuring smooth operation. However, it is essential to ensure that the lubricant is evenly distributed and not over-lubricated, as excessive lubrication can attract dust, leading to potential complications.

Splined shafts have revolutionized power transmission in various industries with their unique design and functionality. Their versatility combined with countless advantages underlines their importance in modern machinery. As you explore the world of splined shafts, remember that quality and precision are crucial.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: What is milligram mirror treatment?

Great Light CNC Machining Services 29/12/2024 18:46

What is Hauke Energy Mirror Treatment?

‌Hawker Energy Mirror Processing‌ is an innovative metal processing technology that uses the composite energy of activation energy and impact energy to process metal parts. This technology can achieve mirror effect on the surface of metal parts and achieve surface modification in one processing process. Haoke energy technology processes the metal surface through the combined action of high-frequency, high-energy mechanical energy and thermal energy (slightly above room temperature), which significantly improves the smoothness of the workpiece treated, increases the microhardness of the surface and significantly improves the surface wear resistance and corrosion resistance of the workpiece.

Haokeneng technology has a wide range of applications, including but not limited to cylindrical processing of shaft parts, flat and end face processing of parts, inner hole processing, processing internal and external surfaces of thin-walled parts and the treatment of spherical, curved surfaces. surfaces and special shaped surfaces. This technology not only improves the surface quality of the workpiece, but also extends the service life of the workpiece, so it has important application value in the manufacturing industry.

Hawker Energy technology was invented and named by the Chinese. It represents an exciting technological innovation in China’s manufacturing industry and has even attracted international attention. Due to its unique processing effects and high efficiency, Hawker Energy technology is considered a revolutionary technology that is expected to change the way metal parts are processed globally‌12.

‌Hawker Energy Mirror Processing‌ is an innovative metal processing technology that uses the composite energy of activation energy and impact energy to process metal parts. This technology can achieve mirror effect on the surface of metal parts and achieve surface modification in one processing process. Haoke energy technology processes the metal surface through the combined action of high-frequency, high-energy mechanical energy and thermal energy (slightly above room temperature), which significantly improves the smoothness of the workpiece treated, increases the microhardness of the surface and significantly improves the surface wear resistance and corrosion resistance of the workpiece.

Haokeneng technology has a wide range of applications, including but not limited to cylindrical processing of shaft parts, flat and end face processing of parts, inner hole processing, processing internal and external surfaces of thin-walled parts and the treatment of spherical, curved surfaces. surfaces and special shaped surfaces. This technology not only improves the surface quality of the workpiece, but also extends the service life of the workpiece, so it has important application value in the manufacturing industry.

Hawker Energy technology was invented and named by the Chinese. It represents an exciting technological innovation in China’s manufacturing industry and has even attracted international attention. Due to its unique processing effects and high efficiency, Hawker Energy technology is considered a revolutionary technology that is expected to change the way metal parts are processed globally.

Helpline: 15910974236

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: What is knurling?

Great Light CNC Machining Services 29/12/2024 17:44

Knurling is a manufacturing technique usually performed on a lathe that involves creating complex patterns on the surface of a part. These patterns can consist of straight lines, angles, or interlocking patterns. The knurling process improves the durability and aesthetics of the part while improving its grip. However, be aware that knurling patterns may vary. It can have straight ridges or a spiral arrangement of these “straight” ridges, unlike the more traditional crisscross design.

Knurling is an effective method of remanufacturing parts. In fact, the raised parts of the knurled surface help to reduce the impact of wear on the part. This also comes into play when assembling metal pins into plastic molds.

Knurling is used to make a variety of products such as tool handles, mechanical pencils, pistol grips, barbells, etc. Additionally, knurling is common on dart handles and pedals of BMX bikes. It is also commonly used in the production of surgical instruments.

1. Manual knurling and machine knurling

There are two types of knurling techniques: manual knurling and mechanical knurling. Let’s understand the treatment process separately:

01Hand knurling

Hand knurling requires the use of a hand knurling tool called hand knurling. Depending on the configuration, this tool may contain one or more knurled wheels. Knurled wheels usually come in the form of compact rolling devices whose surfaces are decorated with patterns such as diamonds or diagonal lines.

When the hand knurling is firmly fixed on the material surface and starts to work, the rollers exert pressure on it. This causes deformations and changes to the surface of the material. However, manual knurling has fundamental inaccuracies and its operation must be continuous and uninterrupted to avoid overlapping knurling lines.

This process is typically used for small parts that can be handled manually. Therefore, it produces simple knurling patterns, whereas manual processes produce complex machining.

02Machine knurling

The mechanical knurling technique is performed using a machine, usually a manual or CNC lathe. First, attach the workpiece securely to the lathe. The wheel is then attached to the knurled bracket and secured to the workbench. The machine knurling process involves a wheel contacting the workpiece to create the desired knurling pattern. This knurling operation is carried out continuously and generally without error.

To ensure smooth operation and ease of cutting, the blank is usually lubricated before turning. This prevents overheating and improves the interaction between the blank and the cutting tool. Additionally, constant chip removal must be maintained to prevent buildup, which could lead to machine interruptions and faults.

Machine knurling can accommodate parts of different sizes, lengths and materials. The use of precision tools and feeding devices enables the production of complex knurling patterns with fine spacing and ensures tight control of dimensional accuracy.

2. Knurling process

Knurling technology requires the use of specialized knurls to produce the desired pattern on the surface of the part. The following describes how the process is carried out:

Step 1: Choose the Right Part Material

The material should be malleable enough to move when pressed with a knurled tool. Aluminum, brass, mild steel and various plastics are commonly machined materials. Harder materials may require the use of special knurling tools and slower speeds.

Step 2: Choose the appropriate knurling method

Manual knurling and mechanical knurling are the two most common knurling methods. The first uses a small roller tool that is pressed against the surface of a part to produce the desired pattern. The latter uses a lathe to cut the desired pattern on the part. Hand knurling works best on softer metals, but mechanical knurling achieves finer detail in harder materials.

Step 3: Install the wheel or tool

Knurled wheels are available in a variety of tooth shapes, angles and materials to accommodate a variety of uses. The shape of the tooth determines the pattern and strength of the knurling. They are held in place by knurled brackets mounted on the workbench. The knurling tool contains a mirror image of the intended knurling pattern.

Step 4: Install the artifact correctly

The workpiece is held between the centers or in the lathe chuck. The workpiece must be clamped properly to prevent it from slipping under the pressure of the knurling.

Step 5: Perform the knurling operation

The rotating part is powered smoothly by a wheel or knurled tool. To achieve a uniform knurling effect, vertical alignment and consistent pressure are crucial. The surface of the material then deforms as the wheel or tool continuously feeds the part while applying constant pressure. This results in ridges or depressions on the surface of the part. In harder materials, sharp, high knurling may require multiple passes.

3. The art of knurling

01 straight/standard knurl

Straight knurls can carve straight lines and groove patterns into the surface of workpieces. The technique generally involves creating intersecting lines (parallel or diagonal) with a specialized knurling tool equipped with two hardened wheels with diagonal teeth.

The linear knurled pattern can be used as a decorative pattern to enhance the visual appeal of various room surfaces. This technique is ideal for cylindrical objects such as handles and knobs. Additionally, it proves to be a suitable choice for a variety of uses, including luxury writing instruments, personalized hardware or jewelry, giving it an elegant and stylish look.

02 Diagonal knurling

Diagonal knurling is a specialist processing method used across a wide range of industries to impart textured patterns or gripping properties to cylindrical or rounded surfaces. It is divided into two categories:

Left diagonal knurling

When viewed from the end of cylindrical objects, they have diagonal ridges angled from the upper right to the lower left. A knurling tool configured with edges matching this pattern is used to create a left-hand knurl. These special dials do their job in situations where counterclockwise rotation or rotation represents the preferred direction.

Diagonal right hand knurling

When viewed from the ends of cylindrical objects, they have diagonal ridges angled from the upper left to the lower right. These knurls are formed using a knurling tool with ridges that fit in that direction. Right-hand knurling is generally used in clockwise rotation or rotary motion.

03Diamond knurling

Diamond knurling is a standard method of creating a pattern of small diamond-shaped ridges or indentations on the surface of a workpiece. This involves joining crossed diagonals to form several diamond-shaped projections. A single diamond knurled wheel improves the wear resistance and overall durability of the workpiece and is widely used in machine parts, tools and decorations that have frequent contact or high friction.

Diamond-shaped indentations or textures evenly distribute pressure and wear, reducing the risk of damage or damage. The technology produces intricate and beautiful knurled patterns on machined components such as bicycle parts, lighter housings or personal accessories.

04Special knurling

With concave knurling, the teeth of the knurled wheel have a curvature toward the center of the wheel surface. This configuration is typically used to axially engage and manipulate a single part of a part.

On the other hand, convex knurling is more suitable for long transverse knurling operations. Its rounded shape facilitates smoother movement across the surface of the part.

Bevel knurling is another variation that consists of angled or beveled ridges that create a distinct beveled edge on the workpiece. These special types of knurling are often used for aesthetic or practical purposes.

4 practical advantages of knurling

01Improve grip and safety

The knurled surface increases surface friction for a secure grip even in slippery conditions. This increases security and control. Knurling components such as bolts, knobs, wheels and rollers helps prevent slipping during assembly or use.

02Aesthetic improvement

In addition to its practical benefits, knurling can also add beauty to an object. Knurling creates a visually appealing and exciting looking textured pattern.

03Improve paint adhesion and brand awareness

Knurling increases the surface area of the material, which is beneficial for brand identification and paint adhesion. The textured surface improves paint adhesion for longer lasting results. Manufacturers can also use knurled patterns to add an element of brand identity to their products.

04Availability of features in various industries

The knurling process benefits many industries. From piping equipment to automotive components, the knurling process is used in a wide range of engineering and manufacturing applications.

5 challenges and limitations of knurling processing

01Material considerations

Not all materials are suitable for knurling. When deciding whether or not to use knurling, the hardness and flexibility of the material must be considered. Some materials, particularly soft plastics, may not withstand this process and may become warped or damaged.

02Surface finish and precision requirements

Knurling it precisely and applying a proper surface finish can be a challenge. This technique may leave burrs or other imperfections. Some procedures require additional machining or surface treatment in order to meet quality standards.

03Potential weakening of the surface

Knurling can sometimes weaken the material, especially if it has an intricate design or is used on fragile materials. Engineers and manufacturers must carefully weigh the tradeoffs between increased grip and potential structural defects when using knurling.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: What is blind hole treatment?

Great Light CNC Machining Services 29/12/2024 16:44

A blind hole refers to a hole countersunk or drilled on the part to connect the surface layer and the inner layer without penetrating the other side of the part. Additionally, you must machine the blind hole with optimum precision to ensure that the blind hole ends at the specified depth in the part.

Blind holes are an essential part of machining, allowing engineers to add grooves, secure attachment points or aesthetic purposes to different components. However, machining blind holes can present some challenges, so it is necessary to understand machining blind holes in various parts. Nonetheless, it is recommended to consider variables such as alignment, depth, and debris accumulation that can affect hole functionality when machining blind holes.

1. How to Drill Blind Holes

The optimal expected thread engagement of the fastener determines the depth of the hole and the additional depth that allows the tap to thread to the correct depth. You can use a hand drill to create blind holes in different ways. However, it is not easy to drill to a precise depth or make vertical holes with a hand drill.

Additionally, a piece of tape wrapped around the drill bit can indicate the depth of the hole drilled. Alternatively, there are other hand drills that have a depth indicator protruding from the front end that physically prevents the bit from drilling too deeply once the desired depth is reached.

Generally speaking, it is more ideal to drill blind holes with a drill press than with a hand drill. A drill press can drill vertical holes, but a hand drill cannot, because hand drills are manually operated and pose a risk of inaccuracy. Additionally, the drill press has a depth indicator that serves as a visual guide to ensure you are drilling to the correct depth. The base of the drill and the axis of the drill must be kept in a vertical position.

Advanced drilling techniques typically involve the use of a lathe, CNC mill, or CNC drill press. Lathes allow the drill bit to be placed in the tailstock and the rotating material or workpiece to be fed into the stationary drill bit. Therefore, this technique creates the most precise holes. However, if the hole requires precision, you can reduce the size of the hole and use a reamer to finish the hole.

Regardless of the technique used to drill blind holes, it is recommended to ensure that the bit has a continuous supply of cutting fluid and continues to cut into chips. You can do this by periodically retracting the bit to flush debris from the hole. Failure to lubricate the bit and clean the hole may damage the bit or jam it in the hole.

2. Clearance of blind hole drilling depth

When drilling a blind hole for tapping, it is essential to drill to the appropriate depth to provide the tap with enough space to cut or machine the required number of threads. This provides sufficient thread engagement for fastening for maximum holding force and sufficient clearance for the tap.

Note, however, that the type of tap required, material thickness, intended depth of the embedded element, design requirements and intended application will often affect the depth of the hole.

For example, to get the correct number of threads, a taper tap requires a deeper hole than a helical flute tap or a bottom tap. In fact, it has a longer tip and entry to cut wires to the full depth.

Most importantly, the depth of blind holes should not exceed the thickness of the material to avoid compromising the integrity of the material being processed. This may weaken the frame or product. Therefore, refer to the design specifications to machine blind holes to a depth suitable for the intended use.

3. What other types of holes are there in machining?

Different holes are suitable for different applications. Here are some types of holes:

Tapered hole: This type of hole has a gradual change in diameter. They start wide and narrow as they move deeper into the room. The cones generally pass through the entire material; they are intended for taper pins and not fasteners.

Counterbore: A counterbore is a standard hole with a larger hole above it. The hole usually has a flat bottom, which prevents the Allen fastener from ejecting from the surface of the part. They are suitable for machining bolts or screws on workpieces.

Countersink: This type of hole combines a countersink and a countersunk hole. It features a countersunk top that transitions into a countersink that moves into a pilot hole. They are generally suitable for hex countersunk head screws.

Countersinks: Countersinks are typically shallow holes or surface countersunk holes used to create a flat contact surface between the underside of the fastener and the material being joined perpendicular to the centerline of the hole.

4. The difference between through holes and blind holes

A through-hole is a hole that passes through the entire component and is open at both ends. In contrast, a blind hole has an opening on one side and no penetration on the other side.

Blind holes have a specified depth. However, your part will require different taps depending on the core drill selected.

5. How to clean blind holes

When drilling blind holes, it is essential to remove debris, as failure to remove it can lead to problems such as wear and breakage of the drill bit. You can use air or a high-pressure jet of coolant to blow debris out of the holes. However, if the hole is too deep, the drill grooves may not remove debris effectively.

Additionally, it is recommended to clean the hole again to remove any remaining debris after drilling. So in this case you can use a manual airsoft gun. You can also use a specialized handheld hole cleaner to blow compressed air into the hole while vacuuming the blown debris into a closed container.

6. Engineering skills for drilling blind holes

Although machining blind holes can be difficult, here are some helpful tips:

Use a drill press to deal with blind holes. It provides greater control and precision throughout the drilling process.

When drilling materials, choose a drill bit that fits your drill press. It is crucial to use the correct size and type of drill bit. Choosing the right drill bit is the perfect drill bit for drilling clean, precise holes.

Before drilling, mark the depth of the hole on the drill bit with a marker or tape. This helps prevent machining errors such as through drilling and holes cut too deep.

It is always best to start drilling blind holes slowly. This ensures precise, clean drilling and prevents the drill bit from deviating from its intended path.

When drilling into metal, apply cutting lubricant to the bit. It helps drill clean holes while preventing the bit from overheating or breaking.

For larger diameter holes, it is recommended to drill a pilot hole first. This provides control over larger drill bits and ensures the hole is straight.

Clean the port with compressed air or a vacuum cleaner to remove any debris or dust.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: What three eccentricities does a triple eccentric valve refer to?

Great Light CNC Machining Services 29/12/2024 15:41

The three eccentricities of a triple eccentric valve are: spindle eccentricity, ball center eccentricity and sealing surface eccentricity.

Three eccentricities

1) The offset of the valve plate from the center of the valve body;

2) The offset of the valve shaft relative to the central axis of the valve body;

3) The central axis of the valve shaft is offset from the axis of the cone angle of the valve seat.

Characteristics of the triple eccentric valve

1) Good sealing performance: The sealing of the triple eccentric butterfly valve is achieved by extrusion between the sealing surfaces of the valve. The higher the closing torque, the higher the sealing level and “zero leakage” can be achieved.

2) Zero friction: reduces the friction phenomenon of the valve during the switching process, thereby significantly increasing the life of the valve.

3) Large flow rate: Due to the superiority of the triple eccentric structure, the flow diameter of the valve is increased and the valve has a higher flow rate.

4) Short stroke: When the valve opens and closes, the valve shaft only needs to rotate between 70-90°, which shortens the opening and closing time of the valve and allows quick closing.

5) Wide range of use: The eccentric metal triple seal butterfly valve has a wide range of temperature and pressure adaptability, the temperature can be between -196 and 650 ℃ and the pressure can be between PN10 and PN160 (ANSI CL 150 ~ CL900).

6) Long service life: Eccentric triple metal seal butterfly valve is a metal-to-metal seal valve with good wear resistance and no deformation after long-term operation. Additionally, at the time of opening, the valve seat and the sealing ring. are separated without friction, so this valve has an extremely long lifespan.

7) Adjustment performance: The eccentric metal triple seal butterfly valve has an adjustment function and is often used as a control valve.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: Let’s talk about gears, a basic industrial component, in the simplest way possible.

Great Light CNC Machining Services 29/12/2024 14:36

Recently, friends who are not professional in the field of gears but are involved in this field asked a question: How to use less professional vocabulary to explain what gears are? Some names on the English drawings are noted in passing. Let’s try talking about gears this way. It’s a bit long, so friends who want to know more can be patient and take it down.

Cars, clocks, can openers, and many other devices use gears in their mechanisms to transmit power through rotation. A gear is a circular mechanical device (some gears are also non-circular) with teeth that mesh to transmit rotation on an axis. They are an extremely valuable piece of machinery due to their wide range of applications.

What is a gear?

A gear is a wheel with teeth on its circumference. Gears are usually grouped together and are used to transmit rotation from the shaft of one gear to the shaft of another gear. The teeth of a gear on one shaft mesh with the teeth of a gear on the other shaft, creating a relationship between the rotation of the two shafts. When one axis rotates, the other axis also rotates. Two different sized gears will spin their two axes at different speeds, you will learn more about this, as well as the different types of gears and where they are used.

Why use gears?

Gears are a very useful transmission mechanism for transmitting rotation from one shaft to another. As I mentioned before, you can use gears to change the output speed of the shaft. Let’s say you have an engine that runs at 100 rpm and you want it to only run at 50 rpm. You can use a gear system to reduce speed (and also increase torque) so that the output shaft turns at half the speed of the motor. Gears are often used in high-load situations because the teeth of the gear allow finer, more discrete control of shaft movement, an advantage that gears have over most pulley systems. Gears can be used to transmit rotation from one axis to another, and special types of gears can transmit motion to non-parallel axes.

gear parts

Teeth – The teeth of a gear, a serrated surface that projects outward from the circumference of a gear and is used to transmit rotation to other gears. The number of gear teeth must be an integer. A gear will only transmit rotation if its teeth mesh and have the same tooth profile.

Axis – The central axis of the gear, a point when viewed from the front.

Pitch Circle – The pitch circle of a gear, which is a circle measuring the size of a gear.

Pitch Diameter – The pitch circle diameter two gears must have the same pitch diameter to mesh.

Circular picth ——The pitch of the gear, that is, the length of the arc from the center of one tooth to the center of the other tooth on the pitch circle

Pressure angle——The pressure angle of the gear, how to express this in simple terms? When a pair of gears mesh (contact), the angle between the direction of force and the direction of speed of travel doesn’t seem to be well understood, so let’s leave it at that.

Calculate gear ratio

As mentioned earlier, gears can be used to reduce or increase the speed or torque of a drive shaft. In order to drive the output shaft at the required speed, a gear system with a specific speed ratio is needed to produce that speed.

The system speed ratio is the ratio of the input shaft speed to the output shaft speed. There are many ways to calculate the gear ratio in a two-speed system. The most common method is to determine the number of teeth (N) on each gear. To calculate the gear ratio (R), the formula is: R=N2/N1

Where N2 represents the number of teeth of the gear connected to the output shaft, and N1 represents the number of teeth of the gear connected to the input shaft. The left gear in the first picture above has 16 teeth and the right one has 32 teeth. If the left gear is the input shaft, the ratio is 32:16, which can be simplified to 2:1. This means that for 2 revolutions of the left gear, the right gear will make one revolution.

The gear ratio can also be used to determine the torque output of the system. Torque is defined as the tendency of an object to rotate about its axis; essentially the rotational power of the axis. A shaft with more torque can turn larger objects. The gear ratio R is also equal to the ratio of the output shaft torque to the input shaft torque. In the example above, although the 32-tooth gear rotates more slowly, it produces twice the rotational power of the input shaft.

Gear type

There are many types of gears and gear mechanisms, and certainly not all of them will be covered here. We’ll start with some of the simplest gears and gear mechanisms and then move on to some of the more complex and interesting gears and gear mechanisms.

spur gear

Spur gears are the most common and simplest type of gear. Spur gears are used to transmit motion from one axis to another parallel to it. The tooth grooves on the two upper end faces of the spur gear face each other, and the shape and position are exactly the same. When two adjacent spur gears mesh, they rotate in opposite directions.

gearbox

Is this a bit familiar? It can hardly be called a gearbox. The gearbox receives rotation from the input shaft (usually the motor shaft) and changes the speed and power of the input shaft through a series of gears to the required speed. or torque rotates the output shaft. Transmissions are generally classified based on their overall speed ratio (the ratio of input shaft speed to output shaft speed).

bevel gear

A bevel gear is a gear used to transmit power from one shaft to another non-parallel shaft. Bevel gears have angled teeth, which actually makes the shape of their “pitch diameter” conical. This is why most bevel gears are classified based on the distance from the large end face of the gear to the tip of the imaginary cone that would form if the gear teeth protruded. For two bevel gears to mesh, each imaginary bevel tip must intersect at the same vertex. When two bevel gears are the same size and rotate an axle at a 90 degree angle, they are called “helical gears.”

rack

The rack and pinion converts the rotational motion of the gear (pinion) into the linear motion of the rack. The pinion is like any other spur gear in that it meshes with the rack (a track with teeth). As the gear turns, the rack slides continuously.

internal gear

Internal gears are gears with teeth on the inside rather than the outside. Internal gears can be used to reduce the space a transmission takes up or to allow something to pass through the center of a shaft as the gear rotates. Unlike ordinary spur gears, internal gears rotate in the same direction as ordinary spur gears. In most cases, internal gears are used in planetary gearboxes. Let’s take a look at planetary gearboxes.

planetary gearbox

A planetary gearbox is a special type of gearbox that uses internal gears. The main components of a planetary gearbox include the sun gear, which is located in the center of the gearbox and is usually connected to the input shaft of the system. The sun gear rotates several planetary gears, which simultaneously rotate a large internal gear, called a ring gear. Planetary gears are usually held by brackets that prevent them from rotating around the planetary gear. Planetary gearboxes can handle higher loads than most reducers because the load is distributed across all planetary gears rather than just one spur gear. These gearboxes are ideal for large reductions in tight spaces, but can be expensive due to their complex design and require good lubrication.

Worm gear

A worm gear is a gear driven by a worm, a small screw-shaped component that meshes with the gear. The gear rotates about an axis perpendicular to the worm, but not in the same plane as the worm. For each revolution of the worm, the gear turns one tooth. This means that the gear ratio of the worm gear is always N:1, where N is the number of teeth of the gear. While most gears have a circular pitch, worm gears have a linear pitch, which is the distance from one revolution to the next in the propeller.

Therefore, worm gears can be used to significantly reduce the speed and increase the torque of the system in a single step and occupying very little space. A worm gear mechanism can achieve a gear ratio of 40:1 using only a 40-tooth gear and a worm, whereas using a spur gear to achieve the same effect would require a pinion meshing with another gear 40 times the size.

Since the worm is helical, it is almost impossible to drive the worm gear in reverse. This means that if you try to turn the system by its output shaft (on the worm gear) rather than by its input shaft (on the worm gear), you will not succeed. not. When driven by a worm, the spiral rotates and slowly advances each tooth. If you reverse the system, the gears will push against the sides of the threads without actually rotating them. This makes worm gears very valuable in mechanical systems because the shaft cannot be manipulated by external forces and reduces backlash and backlash in the system.

Helical gears and herringbone gears

Helical gears are a more efficient gear. The teeth are at an angle to the axis of rotation, so they end up being curved around the gear rather than straight up and down like a spur gear. Helical gears can be installed between parallel shafts, but can also be used to drive non-parallel shafts provided the inclined teeth mesh.

The teeth of spur gears mesh all at once, that is, the entire tooth surface of one gear is in full contact with the tooth surface of the adjacent gear immediately after meshing, while the teeth of the helical gears gradually slide into each other. Helical gears are therefore more suitable for high loads and high speeds. The disadvantage of helical gears is that they require thrust bearings because when the teeth of the helical gear mesh, they create an axial thrust that pushes the gear along its axis of rotation.

This problem can be solved with a herringbone gear, which is essentially two helical gears connected together by teeth at opposite angles. This eliminates the lateral forces produced by the helical gear because the axial force on one side of the herringbone gear cancels the force on the other side. Herringbone gears are more difficult to manufacture than helical gears due to their geometry.

Cage gears and pin gears

Cage gears and pin gears are an easier type of gear mechanism to make because they can be made inexpensively from wooden boards and dowels. However, they are not well suited to high speed or high load situations, as they typically have significant clearance and headroom. Cage gears and pin gears are mainly used to transfer rotation between vertical shafts. A pin gear is essentially a disk with short pins extending from it (forming a spur gear) or across its surface parallel to the axis of rotation (forming a bevel gear). The pins of these gears act like teeth and touch each other to turn each gear. A cage gear consists of two discs between which there is a pin parallel to the axis of rotation. Cage gears can be used like worm gears because each pin on the gear contacts a pin on a regular pin gear. However, the system can be controlled from both sides.

incomplete equipment

This type of gear is a gear whose tooth profile does not extend along the pitch circle. This mangled equipment can be used for many different purposes. In some cases you may not need the entire tooth profile of the gear, as the gear may never need to rotate 360 degrees and you may have a bond, a beam or other mechanism that is part of the missing side of the gear. In other cases, you may want the broken gear to rotate 360 degrees, but you may not want it to rotate all the way to the other gear. If you spin a broken gear with half a tooth missing and its teeth mesh with a full spur gear every 30 seconds, the spur gear will spin for 15 seconds, then stay there for 15 seconds. This way you turn a continuous rotational motion into a discrete rotational motion, meaning the input shaft rotates continuously, the output shaft rotates a little, then stops, then rotates again, then stops again, and so on.

Non-circular gears

Non-circular gears, although rare in the industry, are a very interesting mechanism. The meeting diameter of the gears changes as the gears rotate, so the output speed of the system oscillates as the gears rotate. Non-circular gears can take almost any shape. If both axes of a constrained gear are fixed, then the sum of the radii of the gear at the point of meshing must always equal the distance between the two axes.

ratchet

A ratchet is a fairly simple device that allows a gear to turn in only one direction. A ratchet system consists of a gear (sometimes with teeth different from the standard shape) and a small lever or latch that rotates around a pivot point and catches in the teeth of the gear. The latch is designed and oriented such that if the gear turns one way, the gear is free to turn and the latch is pushed up by the teeth, but if the gear turns the other direction, the latch gets stuck in the gear teeth. and prevents him from moving.

Ratchets are useful in a variety of applications because they allow force to be applied in one direction but not another. These systems are common on bicycles (you pedal forward to turn the wheels, but if you pedal backwards the wheels turn freely), a few wrenches and a large winch to wind up the load.

clutch

A clutch is a device found primarily in cars and other road vehicles that is used to change the speed of an output shaft and to disconnect or connect the rotation of the output shaft. A clutch device involves at least two shafts, an input shaft driven by the power source and an output shaft driving the final device. As an example, I will explain a simple 2 speed clutch setup with reference to the image above. There are two different sized gears on the input shaft (the two blue gears on the upper shaft) and the output shaft contains two gears that mesh with the gears on the input shaft (the gears red and green) but are free to rotate. the output shaft, so they don’t drive it. The clutch plate (the blue grooved piece in the middle) sits between the two gears, turns with the output shaft and slides along it. If the clutch disc is pressed against the red gear, the output shaft will engage and rotate at the speed set by the gear ratio of that gear set (3:2). If the clutch disc is pressed against the green gear, the output shaft is driven into a different gear ratio, defined by this gear set (2:3). If the clutch disc is between the two gears, the output shaft is in neutral and will not be driven.

Clutch plates can mesh with gears in several different ways. Some clutch plates are friction engaged, with friction pads fitted to the sides of the clutch plates as well as the sides of the gears. Other clutch plates (pictured above) are toothed and mesh with specific teeth on the gear surface.

Differential

The gear differential is a very interesting mechanism which consists of a ring gear and four smaller bevel gears (two sun gears and two planetary gears rotating around them) which act as a planetary reduction gear. It is mainly used in cars and other vehicles because it has an input shaft that drives two output shafts (which will be connected to the wheels) and allows the two output shafts to rotate at different speeds when necessary. Ultimately, the average speed of each output shaft should always equal the speed of the ring gear.

If the car is turning, the two wheels will turn at different speeds. The inside wheel will turn faster than the outside wheel because it is closer to the center point of the car’s turn. If both wheels are attached to the same axle, the car will have difficulty turning: one wheel will turn slower than the other, causing drag. Through a differential gear mechanism, the two shafts not only allow the wheels to rotate at their own speed, but are also driven by the input shaft. If one wheel spins faster than the other, the blue planetary gear simply rotates around its axis rather than remaining stationary. The planetary gears now both rotate around their axis and the output shaft (thanks to the bracket), thereby powering both wheels but allowing one wheel to spin faster than the other.

Make something with gears

Gears can be seen everywhere in toys:

Of course, gears can do much more, like this:

And yes, I didn’t expect it!

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Technology: Precautions for automatic tool change in a twin-spindle machining center

Great Light CNC Machining Services 29/12/2024 14:30

The automatic tool change of a twin-spindle machining center is a key link for efficient machining. In order to ensure the smooth running of the tool changing process as well as the quality and safety of processing, the following points require special attention:

1. Preparations before tool change

Cut off the power supply: Before carrying out the tool changing operation, you must ensure that the machining center has cut off the power supply to avoid accidental injuries during the tool changing process.

Check cutting tools and accessories: carefully check whether cutting tools, accessories, drill bits and other parts are intact to ensure that they are not damaged or excessively worn, so as not to affect the processing quality and normal operation of the machine tool. .

Select the tool change point: The tool change point should be selected to ensure that it does not obstruct the movement of the tool, chuck, tailstock and workpiece. Usually, the tool change point can be selected in the upper left corner of the workbench or any place that does not interfere with processing.

2. Precautions when changing tools

Follow operating specifications: Perform tool change operations in accordance with the specifications in the machining center instruction manual. Novices in particular should receive sufficient operating training to improve their operating skills.

Pay attention to the tool change sequence: In a dual spindle machining center, one spindle is used for machining and the other spindle is used for tool change. When changing tools, the processing spindle should come out quickly, and the spindle after changing tools should immediately enter the processing position.

Monitor the tool changing process: During the tool changing process, you should pay close attention to the working status of the machine tool to ensure that the tool changing manipulator, magazine tools and other components are functioning normally and there are no anomalies.

Avoid interference: Ensure that workpieces, accessories and other components do not interfere with the tool or tool changing mechanism during the tool changing process to avoid tool damage or the machine tool.

3. Inspection work after tool change

Check tool attachment: After changing the tool, check whether the tool is properly attached to the spindle to ensure that it is not loose or falling.

Clean the tool holder and cutter: Use appropriate tools to clean chips and impurities on the tool holder and cutter to avoid affecting the processing quality and normal operation of the machine tool.

Quality inspection: After replacing the tool, quality inspection of the tool should be carried out to ensure that the cutting performance and precision of the tool meet the processing requirements.

4. Troubleshooting

Shutdown treatment: If any fault or abnormal situation occurs during the tool changing process, the machine should be stopped immediately and seek professional help.

Record fault information: Record fault time, cause and solution in detail for later analysis and improvement.

In summary, the automatic tool change of the twin-spindle machining center must follow a series of precautions to ensure the smooth running of the tool change process and the quality and safety of the processing. In actual operation, it needs to be adjusted and optimized according to specific situations to adapt to different processing needs and conditions.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: Why are blind holes essential in machining?

Great Light CNC Machining Services 29/12/2024 13:33

1. The main advantages of blind holes

Blind holes have many unique mechanical design and manufacturing advantages, making them widely used in various application scenarios. Here are the main advantages of blind vias:

01Structural integrity and strength

Does not weaken the resistance of the part

Maintains material integrity: Blind holes do not penetrate the part and therefore preserve the material on the other side of the part, helping to maintain the overall structural strength of the part.

Reduce stress concentration: Compared to through holes, blind holes reduce the stress concentration around the hole, thereby reducing the risk of part cracking in a high stress environment.

02Improve sealing and leak resistance

Better sealing performance

Suitable for sealing applications: Since the bottom of the blind hole is closed, it is widely used in occasions requiring sealing (such as hydraulic cylinders, pneumatic cylinders, containers, etc.) and can effectively prevent liquid leakage or gas.

Reduce leak paths: The blind hole design reduces potential leak paths, ensuring the system is leak-tight and reliable.

03Aesthetics and quality of appearance

No penetration marks on the exterior surface

Keep the appearance intact: Blind holes will not leave holes or defects on the other side of the part, ensuring the quality and beauty of the part, especially on products with high appearance requirements.

Prevent external contamination: Because blind holes do not penetrate the part, they are not exposed on the exterior surface of the part, reducing the risk of external contaminants entering the hole.

04Precise positioning and fixing

High precision assembly and positioning

Suitable for hole positioning: Blind holes are often used for precise positioning, which can ensure the precise alignment of assembled parts and avoid deviations.

Improves assembly strength: Blind holes provide a stable contact surface, suitable for fixing screws, pins, etc., improving the overall assembly strength.

05Versatility and flexibility

Wide range of applications

Diversified uses: Blind holes can be used for fixing, assembly, guiding, positioning, etc. of mechanical parts, and have strong adaptability.

Suitable for complex structures: In complex parts and structural parts, blind holes offer flexible processing options, especially in thin-walled areas or locally where strength must be maintained.

06Material savings and cost control

Higher material utilization

Material savings: Since blind holes do not penetrate the part, material waste is reduced, especially in expensive or difficult to machine materials, this saving is more significant.

Reduced machining costs: Blind hole machining typically involves fewer steps and tool wear, thereby reducing machining costs in certain applications.

07Improve security

Prevent damage from penetration

Protect the internal structure: The blind hole will not penetrate the entire workpiece, avoiding damage to the internal structure or other functional components caused by the hole penetration, especially in precision instruments or equipment.

Reduce potential hazards: The blind hole design avoids the risk of the part being completely pierced during processing or use, thereby improving product safety.

08Reduce post-processing and processing steps

No need to cut the back

Reduce post-processing: Since blind holes do not penetrate the workpiece, there is no need to cut or further process the back of the workpiece, reducing processing steps.

Improve production efficiency: reduce processing time and procedures, improve production efficiency, especially in mass production, this advantage is more obvious.

09Suitable for a variety of connection methods

Supports multiple login forms

Suitable for threaded connections: Blind holes are often used to process threaded holes, achieving reliable threaded connections with bolts, screws, etc., and are widely used in mechanical assembly.

Flexible connection options: Blind holes can be used for riveting, pinning, welding and other connection methods, providing more design and assembly flexibility.

2. Why are blind holes essential in machining?

Blind holes have unique advantages and importance in machining, making them an essential machining feature in many applications. Here are some main reasons why blind holes are essential in machining:

01Meet specific design requirements

structural integrity

Maintain part strength: Blind holes will not penetrate the part and maintain material integrity. Especially in parts that need to maintain structural strength, blind holes can avoid weakening the part and ensure mechanical performance.

Aesthetic

Appearance requirements: In some products with high appearance requirements, such as consumer electronic equipment, precision instruments and decorative parts, the use of blind holes can avoid leaving holes on the outer surface of the room and maintain the integrity and aesthetics of the appearance.

02Improve sealing performance

Prevent leaks

Sealing applications: In hydraulic cylinders, pneumatic devices and other components requiring high sealing, the blind hole design can effectively prevent liquid or gas from leaking out of the holes, ensuring sealing and functional stability of the system.

Protect internal components

Avoid the leakage risk caused by penetration: In complex mechanical devices, blind holes avoid the leakage risk caused by hole penetration, thereby protecting the internal structure and functional components from being affected.

03Precise positioning and assembly

key positioning role

For positioning and fixing: Blind holes are often used in precision assembly processes as positioning holes or mating holes. It can ensure the precise alignment of parts during assembly, avoid assembly errors, and improve the overall accuracy of the product.

Support and connection functions

Threaded Holes and Mating Holes: Blind holes are used to process threaded holes and cooperate with bolts, screws or other fasteners to provide reliable connection and support. They are widely used for fixing and connecting various mechanical equipment.

04Adapt to diverse application needs

Versatility

Suitable for a variety of application scenarios: Blind holes can be used for fixing, guiding, positioning, connecting and other functions to adapt to a wide range of application needs, whether it whether high precision instruments, heavy machinery or consumer products, blind holes. play an important role.

Design flexibility

Support for complex structures: In the design of complex parts, blind holes provide greater design flexibility and can achieve the required processing characteristics without affecting other functions.

05Reduce manufacturing and maintenance costs

Reduce material waste

Material saving: When processing blind holes, only necessary materials are removed, avoiding material waste caused by through holes. This saving is particularly important when processing expensive or rare materials.

Simplify post-processing steps

Reduce further processing: blind holes do not penetrate the part, so there is no need for cutting or additional processing on the back of the part, reducing subsequent processing steps and time, thereby reducing costs manufacturing.

06Improve security and reliability

Avoid potential damage

Protect the internal structure: Blind hole design can avoid penetration damage during processing or use and protect key components inside the part. Particularly in precision machines and sensitive equipment, this protection is crucial.

Reduce stress concentration

Improve fatigue life: By reducing stress concentration, blind holes reduce the risk of fatigue failure of parts in high-stress environments, thereby extending the life and reliability of mechanical components.

07Easy to assemble and maintain

Easy to disassemble and assemble

Convenient threaded connection: Blind holes are often used for processing threaded holes to facilitate the installation and removal of bolts or screws, especially in mechanical equipment requiring frequent assembly or maintenance. This feature of blind holes greatly improves the convenience of operation.

Reliable positioning capabilities

Precise component fit: Blind holes are used for precise component positioning to ensure reliable fit of each part, helping to simplify the assembly process and improve assembly quality.

Blind holes are essential in machining mainly because they can meet specific design requirements, improve sealing performance, provide precise positioning and assembly functions, adapt to various application needs , reduce manufacturing and maintenance costs, improve safety and durability, and easy assembly and ease of assembly. interview. By properly designing and using blind vias, machine manufacturers can significantly improve product quality, performance and lifespan while reducing cost and complexity. Blind holes therefore occupy an irreplaceable and important place in machining.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: How many of the 10 mechanical properties of materials do you know?

Great Light CNC Machining Services 29/12/2024 12:30

Mechanical properties of materials refer to the different physical properties and deformation behaviors of materials under the action of external forces. These properties are important indicators for evaluating the suitability of materials under different application conditions. Here are some key mechanical properties and their interpretation:

Ten mechanical properties

01Intensity

tensile strength

Definition: Maximum stress a material can withstand before breaking during a tensile test.

Importance: A measure of the bearing capacity of a material under tensile loads, often used in the design and analysis of structural members.

Yield strength

Definition: Stress value when the material begins to undergo significant plastic deformation.

Importance: One of the key parameters that determines the maximum load a material can support without permanent deformation.

Compressive strength

Definition: The maximum stress that a material can withstand under compressive loading until failure occurs.

Importance: Used to evaluate the performance of materials under pressure, such as columns, bases and other structures.

Shear resistance

Definition: The maximum stress at which a material fails under shear loading.

Importance: Used to analyze the bearing capacity of connectors, bolts, etc. under a shear force.

02 hardness

Definition: The ability of a material surface to resist being dented or scratched by hard objects.

Importance: Hardness is related to wear resistance and scratch resistance and is an important indicator for evaluating the wear resistance of materials.

Test method

Brinell Hardness (HB): Use a carbide ball to press the surface of the material and measure the diameter of the indentation to determine the hardness.

Rockwell Hardness (HR): Hardness is determined by driving a conical or spherical indenter into the surface of the material and measuring the depth of intrusion.

Vickers Hardness (HV): Use a quadrangular diamond pyramid to press the surface of the material and measure the diagonal length of the indentation to determine the hardness.

03Resistance

Definition: The ability of a material to absorb energy and deform plastically without breaking, generally measured by impact testing.

Why it matters: High toughness materials are able to resist failure under impact loads and are suitable for manufacturing components subjected to high dynamic loads.

Shock resistance

Definition: The energy absorbed by a material subjected to impact loading, generally measured by the Charpy or Izod impact test.

Application: Evaluate material performance in low temperature or high impact environments.

04ductility

Definition: Ability of a material to deform plastically under stress without breaking, generally expressed by an elongation and reduction in surface area.

Why it matters: Ductile materials can stretch, compress, or bend during processing without cracking, making them suitable for making parts with complex shapes.

Elongation

Definition: degree of deformation of a material before failure during a tensile test, as a percentage of its original length.

Application: Used to evaluate the plastic deformation capacity of materials.

Shrinkage of the area

Definition: Reduction in cross-sectional area as a percentage of the original area after the material fails in a tensile test.

Application: Evaluate the ductility of materials in conjunction with elongation.

05 fragility

Definition: Property of a material to fracture without significant plastic deformation when subjected to stress.

Why it matters: Brittle materials often break suddenly without significant deformation. Very brittle materials should be avoided in designs, particularly under dynamic loading or impact conditions.

06 Flexibility

Definition: Ability of a material to deform under the action of external forces and to return to its initial shape once the external forces are removed.

Why it matters: The modulus of elasticity (Young’s modulus) is a measure of a material’s ability to resist elastic deformation and is often used in the design of elastic elements such as springs.

elastic modulus

Definition: The proportional relationship between stress and strain, indicating the stiffness of the material.

Application: Used to calculate the deformation of materials in the elastic range and evaluate the stiffness and elastic recovery capabilities of materials.

07Fatigue resistance

Definition: The ability of a material to withstand millions of repeated loads without breaking under cyclic stress.

Importance: Fatigue resistance is related to the lifespan of materials and is an important indicator for evaluating the long-term performance of materials under dynamic loads or in vibration environments.

application

Suitable for dynamic components: Components subject to cyclical loading, such as shafts, springs and gears, require materials with high fatigue resistance to extend their service life.

08 Creep

Definition: Slow plastic deformation of materials over time under the action of high temperature or constant stress.

Importance: Creep is one of the leading causes of material failure in high temperature environments and is particularly critical in high temperature equipment such as turbine blades and boiler pipes.

Creep resistance

Definition: Ability of a material to withstand long-term loads at a certain temperature without creep failure.

Application: Used to evaluate the long-term performance of equipment materials at high temperatures.

09Breaking strength

Definition: Capacity of a material to resist crack propagation, maximum stress intensity factor that the material can withstand in the presence of existing cracks.

Importance: Used to evaluate the material’s ability to resist failure in the event of cracks or defects, particularly important in parts with high reliability requirements.

10 Anti-fatigue performances

Definition: The ability of a material to resist fatigue damage and fracture under cyclical stress conditions of repeated loading and unloading.

Importance: For components subject to cyclic loads, such as flywheels, shafts, springs, etc., fatigue resistance is crucial and determines their service life.

The mechanical properties of materials are important indicators for measuring the performance of materials under various loading conditions. These properties directly affect the application range, service life and safety of the materials. In engineering design, understanding and rational selection of mechanical properties of materials can ensure that product reliability, durability and performance meet design requirements.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: 12 causes of tool wear, how many do you know?

Great Light CNC Machining Services 29/12/2024 10:28

Tool wear is a common problem in mechanical processing, which directly affects processing quality, production efficiency and manufacturing costs. Understanding the causes of tool wear and their solutions can effectively extend the tool life and improve the processing effect. Here are the main causes of tool wear and the corresponding solutions:

1. Main causes of tool wear

1. Causes of excessive cutting speed: Excessive cutting speed leads to increased friction and cutting heat between the tool and workpiece, thereby accelerating tool wear. Solution: Depending on the material type and tool characteristics, reduce the cutting speed reasonably to avoid tool wear due to overheating.

2. Reasons for excessive feed: Excessive feed will increase the cutting force, resulting in increased mechanical stress on the tool cutting edge, and the tool is prone to chipping or wear. Solution: Appropriately reduce the feed amount to ensure a smooth cutting process and reduce the load on the tool.

3. Reasons for excessive cutting depth: Excessive cutting depth significantly increases the cutting force supported by the tool, resulting in increased tool wear. Solution: Optimize the cutting depth and adopt a step-by-step cutting method to gradually reach the required depth and reduce the load on the tool.

4. The reason why the tool material is not suitable: the tool material is incorrectly selected and cannot meet the hardness, toughness and other requirements of the processing material, resulting in leads to accelerated wear of the tool. Solution: Choose appropriate tool materials according to processing materials, such as carbide, ceramic, diamond coatings, etc., to improve wear resistance and service life.

5. Reasons for unreasonable geometric angles of the tool: The rake angle, clearance angle and tool tip angle are set unreasonably, resulting in an increase in cutting force or heat buildup, which intensifies tool wear. Solution: Optimize the geometric angle of the tool according to specific processing requirements to ensure reasonable distribution of cutting forces and reduce heat accumulation.

6. Cause of insufficient tool cooling: Insufficient cooling during the cutting process causes the tool to become too hot and accelerates tool wear. Solution: Use sufficient coolant or lubricant to ensure the tool is completely cooled during the cutting process.

7. Reasons for improper selection of cutting fluid: The type or ratio of cutting fluid is inappropriate, which cannot provide sufficient cooling and lubrication effects and accelerate tool wear. Solution: Choose the appropriate type of cutting fluid for the material and tool being processed, and ensure that the concentration and flow rate of the cutting fluid are appropriate.

8. The reason why the workpiece material is too hard: The workpiece material has high hardness, which makes the tool bear greater wear force during the cutting process. Solution: Use tool materials with better wear resistance or reduce the hardness of the workpiece material through heat treatment and other methods.

9. The reason why the tool is not clamped firmly: The tool is not clamped on the machine tool or is not clamped firmly, causing the tool to friction during the process of cuts and worsens wear. Solution: Ensure the tool is securely mounted on the machine tool, using appropriate clamping devices and clamping force.

10. Causes of machine tool vibration: Machine tool vibration or instability will cause uneven force on the tool during the cutting process, thereby accelerating wear. Solution: Improve the rigidity of the machine tool, reduce vibration sources and ensure stable processing.

11. Reason for poor chip evacuation in the cutting zone: Chips accumulate in the cutting zone, forcing the tool to recut the processed chips and increasing tool wear. Solution: Use an efficient chip removal device or remove chips regularly to ensure a clean cutting area.

12. Reasons for poor processing environment: The temperature, humidity or other factors in the processing environment are unstable, which affects the performance and wear of the tool. Solution: Improve the processing environment, control temperature and humidity, and reduce the negative impact of the environment on the tool.

2. Solutions

1. Optimize the cutting parameters and reduce the cutting speed: according to the characteristics of the processing material and the tool, reasonably reduce the cutting speed, reduce heat generation, and delay tool wear. Reduce the feed amount: Reduce the feed amount appropriately to ensure stable cutting force and reduce tool wear.

2. Select the appropriate tool material. Select the tool according to the workpiece material: such as carbide, ceramic or diamond tools, adapt to materials of different hardness and toughness, and improve the wear resistance of the tool.

3. Adjust the geometric angle of the tool to optimize the cutting angle and clearance angle of the tool: adjust the geometric angle of the tool according to the cutting conditions to make the cutting force and reasonable cutting heat distribution and reduce tool wear.

4. Improve the cooling and lubrication system and use sufficient coolant: ensure adequate coolant supply, lower the cutting zone temperature and reduce thermal wear of the tool. Choose the right lubricant: Choose the right lubricant according to the cutting material to improve the lubricating effect of the cutting process.

5. Maintain and replace tools regularly. Check the condition of tools regularly: discover tool wear problems in time, repair or replace them, and maintain the cutting effect. Replace badly worn tools: When the wear of the tool reaches a certain level, it should be replaced in time to avoid a decline in the processing quality.

6. Improve the clamping of the machine tool and workpiece to ensure that the tool is firmly installed: use high-quality tool clamping devices to ensure the stability of the tool on the machine tool. Improve machine tool rigidity: reduce machine tool vibration, improve the stability of the machining process, and reduce abnormal tool wear.

7. Use an effective chip removal system to ensure rapid chip discharge: Use an effective chip removal system to prevent chips from accumulating in the cutting area and prevent the tool from recutting the chips .

8. Improve the processing environment and control the temperature and humidity of the processing environment: reduce the impact of environmental factors on cutting tools and ensure that cutting tools operate under optimal conditions.

Tool wear is inevitable, but by understanding its causes and taking effective solutions, tool life can be significantly extended and processing quality and production efficiency can be improved. Reasonable tool selection, optimization of cutting parameters, improvement of cooling and lubrication systems, and regular tool maintenance are key strategies to reduce tool wear.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: What is a thrust grinder

Great Light CNC Machining Services 29/12/2024 09:26

‌Push grinder‌ is a special machine tool equipment mainly used for grinding the thrust surface of workpieces. This type of grinder is generally used for high-precision grinding of the flat surface of the workpiece to achieve the required flatness and precision requirements. Thrust grinders are typically designed and manufactured with efficiency, precision and reliability in mind and are suitable for grinding a variety of materials including metals, alloys, etc. In addition, push grinders can be adjusted and configured according to different processing needs to meet specific processing conditions.

Thrust grinders are particularly used in the automotive industry. For example, in the CNC crankshaft thrust surface grinding machine, this equipment is used to precisely grind the thrust surface of the crankshaft to ensure the normal operation and performance of the automobile engine. In addition, thrust grinding machines also play an important role in other fields, such as bearing-specific dual spindle surface grinding machines, which are used to grind bearing planes with high precision to improve performance and the lifespan of the bearings.

Generally, thrust grinder is an important machine tool equipment that plays a key role in industrial production. By providing high-precision and high-efficiency grinding services, it ensures the improvement of product quality and production efficiency.

Helpline: 15910974236

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: Do you really understand surface finishing?

Great Light CNC Machining Services 29/12/2024 08:24

Processes involving the use of machinery introduce typical irregularities in the product surface. The roughness of a product’s surface affects its durability and performance. Hence the need for surface finishing. Continued use often causes the product to wear out over time. This is usually due to high friction between the surface of the product and the surface it is used on. In contrast, a smooth surface with a surface treatment is more durable and has less or no friction.

1. What is surface finishing?

Surface finish is a parameter that determines the physical properties (appearance) of a part. It is a method of modifying the surface of a material through a process that adds, removes or reshapes the metal surface.

Surface finish can be defined by three main characteristics. These are surface roughness, waviness and rolling.

The measurement of total spatial irregularity on a metal surface is called surface roughness. It also describes the number of peaks and valleys on the surface. The lower the number, the fewer irregularities, which means less surface roughness and better surface finish. When professionals talk about surface finish, they usually mean “surface roughness.”

Surface finish measurements can also be expressed in terms of waviness. Ripple is caused by the deflection, curvature, or vibration of particles. Waviness can be measured if a surface has more space between irregularities than other surfaces.

2. Why is surface finish so important?

Surface treatment plays a key role in custom processing by determining how a product reacts to its environment. It is therefore crucial to evaluate the durability and effectiveness of the product during its use.

Surface finish affects many aspects of the ability of product components to resist wear. These include the ability to aid or destroy lubrication, increase or decrease friction with mating parts, and resist corrosion.

Different surface treatment methods have different effects on products. Surface treatment methods have the following functions:

Improves product durability by reducing friction.
It is essential for resistance to chemicals and corrosion.
It helps paints and paints adhere.
This gives the product a specific visual appeal.
Easily eliminates surface defects.

3. How to measure the roughness of a surface?

Measuring surface roughness involves calculating the relative smoothness of a product’s surface profile. It uses Ra as a numerical parameter.

As mentioned above, the three basic components of a surface are roughness, waviness, and blades. These components are crucial in the geometric properties of the surface.

There are several systems for measuring surface finish. These surface finish measurement systems include:

Contact method (pen probe instrument)

The contact method uses a stylus probe instrument to measure the surface condition of a product. First, the stylus is moved along the product surface, then the vertical movement of the stylus is recorded.

The recorded pen profile is then used to calculate the three basic surface roughness parameters. This method requires machine interruption and the pen tip may leave tiny scratches on the product surface.

In order to accurately measure the surface roughness of precision objects, you should ensure that the diameter of the stylus tip is as small as possible and the contact pressure on the surface is small.

Non-contact methods (optical light, laser or x-rays)

The non-contact measurement method uses optical instruments such as X-rays and lasers instead of a stylus to measure the surface roughness without touching the product surface, and the measurement speed is fast.

Optical scattering or ultrasonic scattering is one of the most useful methods here. Optical instruments will send ultrasonic pulses to the surface of the product. This pulse changes, interferes and causes reflections in the instrument. You can now evaluate the reflected waves in the instrument to determine surface roughness parameters.

Microscopy techniques are also useful for examining microscopic peaks on the surface of materials. Again, these methods provide consistent results.

4. What are the factors that affect surface finish?

Type of coolant used

Using coolant is a great way to improve surface quality and tool life during machining. It effectively reduces surface friction. During the CNC machining process, heat will be generated, which will affect the physical properties of the surface and make it rough.

Using a high pressure coolant may well improve the surface finish, but it is not the most effective solution as it is not suitable for lower cutting speeds. Using the lowest grade coolant has been recognized as the most effective method of reducing surface roughness. This method is inexpensive, less polluting and offers good part performance. Additionally, it reduces tool wear and surface roughness.

Cutting parameters

During processing, surface finish is essential to product quality. However, achieving the desired surface finish depends on cutting parameters such as feed, depth of cut and cutting speed.

When cutting using CNC machine tools, increasing the cutting speed will reduce surface roughness. This means that the faster the cutting speed, the lower the surface roughness (assuming all other parameters remain constant).

As the cutting depth increases in CNC machining, the maximum roughness depth tends to increase. This only happens if other relevant parameters remain unchanged. Additionally, increasing the feed corresponds to a decrease in average roughness during CNC machining.

To improve machining processes, cutting fluids reduce surface roughness in all cutting processes. This is achieved by lowering the tool temperature, thereby reducing the coefficient of friction. However, fluid penetration into the cutting gap can also reduce tool and product adhesion.

Type of processing technology

The type of processing technology used in manufacturing the product determines the surface roughness of the product. The machining process is controlled by two main machining parameters, namely feed rate and cutting speed.

Cutting feeds and speeds used in metal machining processes, such as turning in CNC machining, have a large impact on the surface finish of the final product. The surface value increases with increasing feed, while the surface pattern roughness decreases with increasing cutting speed.

vibration

Unworn or worn tools can cause vibrations that can affect the surface finish of your product. As tools wear, they affect the integrity of the product’s surface finish, vibrating unpredictably to achieve a smoother surface.

The vibration frequencies and amplitudes obtained with uncarried tools influence the surface condition by adding simple sinusoidal vibrations. Vibrations have different amplitudes and frequencies, which means that the average roughness increases as the amplitude of the sine wave increases. Vibration frequency has minimal effect on surface roughness.

5. How to improve surface roughness

During the manufacturing process, there are several ways to improve the surface finish of a product, part or device. It is effective in reducing friction and extrusion between tool and workpiece. Other techniques include sharpening tool edges and ensuring certain materials are properly heat treated. In this way, machine tool vibrations can be reduced.

The most effective ways to improve surface roughness are:

Improve cutting conditions

Proper reduction of surface treatment is a key cutting condition in the production method. Some improvements in cutting conditions include: cutting materials at high speeds, reducing feed rates, using high quality cutting fluids, improving the rigidity of the processing system, and using cutting by ultrasonic vibrations.

Choose the right processing technology

The choice of excellent processing technology determines the surface finish of the product; on the contrary, incorrect or invalid treatment technology may affect the effectiveness and quality of treatment.

Choose the right raw materials

Some parts of equipment or machines are made of different materials, so the choice of different production methods or tools based on the density of different raw materials has a direct relationship with the surface finish.

Achieving the best possible surface finish is essential to product durability and effectiveness. It is therefore crucial to establish strict standards for surface finishing. This must be combined with a cost effective and correct method of producing the required surface finish.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: What are the methods to solve the cutting vibration of a five-axis machining center?

Great Light CNC Machining Services 29/12/2024 07:22

The five-axis machining center is a modern CNC equipment machining center which is not only suitable for processing complex parts of plates, plates, molds and small shells, but also can carry out milling, drilling, reaming, thread etching and thread cutting.

During the machining process, cutting vibration is an inevitable situation during the machining process of five-axis CNC machine tools. This is a vibration phenomenon generated during the cutting process. In fact, reasonable cutting vibrations have little impact on the processing quality, but once the cutting vibrations increase, severe vibrations with amplitudes greater than tens of µm are generally accompanied by loud noises.

If the vibration of the five-axis machining center during the cutting process can exceed 100 μm, then the tool or workpiece may become loose. 100 μM is generally considered the standard for judging whether cutting vibration is reasonable. If the cutting amplitude exceeds 100 μm, processing cannot be continued. When the amplitude is less than 100 µm, although it can be processed, obvious vibration scratches will remain on the processed surface and surface finishing is not allowed. Therefore, cutting vibrations should be limited within a reasonable range.

Here are the methods to solve the cutting vibration of a five-axis machining center:

1. Organize the tool path reasonably

Reasonable tool path layout of five-axis CNC machining center is very important for cutting processing. Milling can be divided into down milling and reverse milling. Whether it is down milling or reverse milling, as long as the direction of the milling force is consistent with the clamping direction of the workpiece, it will help eliminate the vibration of the bent plate component. Current milling equipment, such as CNC milling machines and five-axis machining centers, are equipped with ball or roller screws, which are very useful in eliminating vibrations during the cutting process.

2. Reasonable fit

When CNC machine tools in five-axis machining centers use thin shank end mills to mill deep cavities, the plunge milling method is often used. Plunge milling occurs when the tool advances axially like a drill. When milling deep cavities, the diameter of the long shank is generally greater than 3 times. It is recommended to use the plunge milling method with axial feed. Adjusting cutting parameters is only effective when cutting vibrations are not significant. General adjustment methods are: reducing the rotational speed of the tool or workpiece, reducing the depth of cut, and increasing the number of teeth bent per revolution of the tool or cutter. If vibration occurs during internal thread turning, the number of steps required to complete thread turning can be reduced by 112 cuts. Also use a blade with a positive rake angle and high clearance angle, with a fast chip chute. This insert has the smallest cutting corner angle and lightest cutting speed when filing or milling.

At the same time, the use of sharp blades can reduce the cutting force of CNC machine tools. Rapid grinding of the tool and stability of the processing environment and ground are processing conditions that cannot be ignored.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: What is the cutting speed parameter table?

Great Light CNC Machining Services 29/12/2024 06:20

In the metal cutting process, choosing the appropriate cutting speed is crucial to achieve the best processing results. Unsuitable cutting speed will not only affect the processing quality, but also shorten the tool life. To ensure the correct parameters are selected, the cutting speed parameter table provides an indispensable reference in the metal cutting process.

Users often need to machine particularly hard materials or strict tolerance requirements. The cutting speed parameter table can provide a baseline and recommend the optimal cutting speed for different processing materials. For example, the cutting speed for processing harder metals (like stainless steel, etc.) is lower than that for processing softer materials (like aluminum or copper).

The cutting speed settings table provides recommended cutting speed values. When using a specific tool to process a specific material, a combination of theoretical and empirical recommendations are given as to the cutting speed that can be used to achieve the best results. This cutting speed parameter is provided by tool manufacturers and relevant experts.

The formula for calculating the cutting speed is: (cutting speed x 1000) / (diameter (d) x pi (π))

Cutting speed reference tables usually contain information on cutting speed and tool diameter, feed and tool type (such as drilling, turning, etc.), as well as the different qualities of materials to be machined.

The reference table gives the recommended cutting speed for each tool for each material. This helps users find the right cutting speed for each material to achieve the best results.

Most cutting speed reference tables are divided into different broad categories depending on the type of tool and the material being machined. Recommended values such as cutting speed are given for each category. Typical categories are for example carbide cutting tools, cermets, etc.

Determining the Optimal Cutting Speed

The appropriate cutting speed depends on many factors, including the depth of cut and diameter of the workpiece, as well as the material being machined and the type of tool. This cutting speed reference chart provides clear guidance on combining these factors into appropriate recommendations.

1. Why is the cutting speed reference chart so important?

The reason why this parameter sheet is important is that it helps ensure optimal application of the tool. If the cutting speed is too high, it can cause premature tool wear and even damage the workpiece.

If the cutting speed is too low, the machined surface may be uneven or the tool may get stuck in the workpiece. By using a cutting speed reference chart, you can ensure that you select the correct cutting speed for the material and tool you are working on to get the best results.

Prevent tool wear and damage

Improper cutting speed can cause wear or damage to the tool. If the cutting speed is too high, the tool may break or become dull. If the cutting speed is too low, the tool may get stuck on the workpiece or result in uneven machined surface quality.

Improved efficiency and quality

Using this parameter table can also improve efficiency and quality. If parts are produced with more consistent quality and higher precision, waste of materials and time can be avoided. This allows you to obtain better quality finished products while increasing productivity.

Increased safety thanks to the cutting speed reference table

Another important aspect of proper cutting speed is ensuring process safety. Cutting speeds that are too high not only cause premature tool wear, but can also lead to dangers and accidents. Careful selection of cutting speed is essential, especially when machining large parts or sensitive materials.

2. How to read the cutting speed reference table?

The reference table may seem a little complicated at first glance, but it is actually easy to read. Here are some important points to note:

1. Tool type

First of all, you need to choose the type of tool you are going to use. Most cutting speed reference charts contain information on different types of tools, such as drills, turnings, taps, etc.

2. Materials to be processed

Next, you need to choose the material you want to process. Most cutting speed reference charts contain information on various materials such as steel, aluminum, copper, etc.

3. Diameter

Most reference tables also specify the tool diameter. The larger the tool diameter, the lower the rotation speed should be.

4. Cutting speed (Vc = m/min)

The reference table shows recommended cutting speeds based on material and tool type. This is the speed at which the tool cuts the material.

5. Speed

Finally, a reference table presents recommended speeds (revolutions per minute) for certain materials and tool types. This is the speed at which the tool rotates.

By choosing the appropriate speed, you can extend tool life, reduce processing time, improve surface quality and avoid accidents.

It is important to note that reference tables provide suggestions only and results are always subject to some variation. Therefore, you should provide each tool manufacturer with a parameter table containing recommended values, and then make adjustments based on actual processing results. The exact value may vary depending on machine type, coolant type and other factors.

Overall, this table is an indispensable specimen for metalworkers. It provides optimal parameters for the tool and material to be processed, which can help extend tool life, reduce machining time and improve surface quality.

However, the table should always be a guideline and should take into account the specific circumstances of the site. Careful planning of cutting speeds is an essential process to ensure efficient and safe metal cutting.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: Mass production of large gears

Great Light CNC Machining Services 29/12/2024 05:19

Transmission components used in wind turbines (WTG for short) are all high-load equipment.

Static and dynamic loads will be reflected in the pitch, roll and yaw movements of the tower top and in the structural deformation of the entire drive chain.

Various dynamic reactions occur on the transmission components: spontaneous vibrations of the rotor blades, load changes as each blade rotates, and inconsistent air turbulence acting on the rotor.

All of this can lead to distortion of transmission components and torque fluctuations. The fluctuating torque will far exceed the rated torque value in an instant. Figure 1 shows the load-induced deformation of the rotor, tower, and transmission.

Figure 1: Image showing load-induced transmission deformation (Image source: FVA, Workbench)

Wind turbine drives must be able to withstand static and dynamic loads for decades. Only with modern simulation methods and knowledge of transmission loads can transmission components be optimized to ensure a service life of 20 or 25 years with a utilization rate of 98%.

In addition to advances in simulation tools, advances in materials science for high-purity steel have also contributed to the success of the driveline.

method

Only according to the structural deformation caused by the load can the design engineer set the optimal topography of the tooth surface of each gear, so as to ensure that the pressure when contacting the tooth surface teeth does not exceed the permissible range of material parameters under various load conditions. During production, it is necessary to ensure that the shape of the tooth surface is manufactured accurately. Figure 2 shows a typical modification of a tooth surface.

Figure 2: Typical change in gear tooth surface

Due to the large modulus and width of teeth, form grinding has become the standard method for grinding hard tooth surfaces, allowing a high degree of freedom in tooth surface design.

Being able to change the tooth surface in actual production is a prerequisite for gear design.

Gear production software for Hofler’s RAPID cylindrical gear grinding machines helps design engineers convert expected tooth surface shapes into feasible tooth surface geometries.

The simulation of the system can therefore be carried out under realistic conditions. This prerequisite also facilitates production, as it eliminates the need for an iterative process between design and production to determine whether the gear actually produced meets the required precision requirements.

production ready process

Cost pressure and production growth often lead to process optimization, and ultimately the processing technology becomes powerful and efficient. For the mass production of large gears, the process level and production efficiency of machine tools play equally important roles. Machine tool temperature stability is essential for both. The development of RAPID series gear grinding machines began 20 years ago. Since then, experience has been accumulated and optimizations have been carried out several times.

But the frame and the column of the machine have never changed. They are always made of mineral cast iron.

This includes quartz particles, quartz sand and mineral dust, as well as a small amount of epoxy resin glue. This material gives high-precision grinding machines exceptional material properties: low thermal conductivity, high thermal capacity and ten times greater thermal attenuation than gray cast iron.

Based on this, the dimensional accuracy of large gears within a narrow tolerance range can be guaranteed regardless of the processing time. Excellent damping characteristics ensure high dynamics of the CNC axes, a prerequisite for efficient production.

Gear Alignment Solutions

Heat treatment deformation should be detected before machining, so that the grinding process can be designed to avoid unnecessary “empty tool strokes” and microstructural damage caused by excessive tool feed. To do this, you must move the stylus while detecting the maximum margin.

But what if the maximum tolerance is at the root of the tooth, at the top of the tooth, at the top or at the bottom of the tooth?

The greater the modification required to the tooth flank, the more problematic machining becomes. Extended alignment analysis provides a solution. During the analysis, several measurement points can be defined (see Figure 3). At the end, the position of the grinding wheel for uniform grinding can be calculated from the measurements.

Figure 3: Example of 5 points Example of 9 points Different positions of the measuring points for centering

Figure 4 shows the principle using a single tooth as an example. The unmodified nominal tooth profile is the starting point for assessing tolerances. The margin is the difference between the position measured during measurement and the unmodified position of the tooth profile.

The upper left of Figure 4 shows a single point measurement as an example. When a multi-point measurement is performed, the margin position is different. There is an inclined line segment between two measurement points and a parabola between three measurement points.

Figure 4: Removal of material and material

To determine the material removal, the existing stock and the nominal profile of the tooth to be machined must be taken into account (see lower left part of Figure 4). It is clear that material removal is evolving. If grinding is done in this manner, only the upper left portion will be ground in the first few passes and no grinding shrinkage will occur on the right tooth surface.

In order to minimize the number of passes for grinding the tooth gap, the allowance can be cycled in such a way that the maximum allowance on the left and right tooth surfaces is consistent and its value is as small as possible. Here it is necessary to ensure that the material removal rate is not lower than the minimum value (see the lower right part of Figure 4). With this centered position, the left and right sides can be ground in the first few passes.

The more tooth gaps on the circumference and tooth width are used to calculate the centering position, the closer the grinding allowance for the current thermal deformation is to the minimum grinding allowance. The smaller the grinding allowance, the shorter the processing time.

Figure 5: Optimized process parameters

Process Design Solutions

Since the more reliable the stock assessment, the more likely it is that maximum removal will be achieved, and the number of passes required to grind each tooth space can be determined automatically using different numbers of strokes. This avoids unnecessary passes and material removal beyond the feed limits. Because the number of tool passes will be automatically increased for tooth spaces with large margins.

All measurement data regarding stock and number of passes is presented to the operator (see Figure 5). Rather than blindly relying on algorithms, Gear Production software’s digital assistance systems provide optimal support to the operator.

Archiving and quality assurance solutions

After the grinding process, the gears can still be automatically measured directly on the grinding machine. The correction values of machine tool settings generated based on the report can minimize production deviations as much as possible. Since we are machining tooth surface geometries that can actually be produced, there is no need to use an approximate scheme to calculate correction values: the algorithm will produce accurate values.

In principle, it does not matter whether the measurement results come from an online inspection system of the gear grinding machine or from a gear measuring center. In both cases, if corrections are necessary, the operator is informed before processing the next part (see Figure 6). The different deviations are displayed using the color display of the traffic lights (green, yellow and red) and their meaning is very clear.

automation

Planetary gears weighing up to 2.5 tonnes are extremely common in wind turbines. Automated systems are well suited to this type of machinery. By cooperating with users, although the processing of large-sized wind gears is more difficult than that of mass-produced small gears, appropriate automation solutions can be adopted. As the part is too heavy, it is recommended to use a chassis type loading and unloading device. In order to ensure that the automation system can be connected to the machine tool, it is necessary to adjust the protective cover of the machine tool and add protective devices in accordance with the Machinery Directive regulations. In addition to workpiece processing, the safety measures of the automatic loading and unloading device of the gear grinding machine should be strengthened to ensure data consistency and precise clamping and release of workpieces on the workpiece table. machine tool.

Once the part is clamped on the support, the measuring system integrated into the machine tool detects runout and axial concentricity. If the measured value exceeds the set tolerance, the position will be changed and tightened. If the clamping tolerances are still not met, the part is unloaded from the machine and series production is interrupted.

Figure 6: Visualization of production gaps

in conclusion

Efforts to reduce production costs and improve process productivity have, on the one hand, reduced the distance between development and design, and on the other hand, broken the restrictions imposed on mass production of large gears.

Mass production of large gears cannot simply be applied to designs from other sectors, such as the automotive industry. However, the principles are the same, and reliable gear design and processing solutions can create powerful processing technology.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: Technical status and development trends of gear sharpening technology

Great Light CNC Machining Services 29/12/2024 04:18

The load capacity, stability of movement and service life of gears mainly depend on the contact conditions of the meshing tooth surfaces under actual working conditions. The microgeometry of tooth surfaces has a huge impact on vibration, noise and gear life. Precision processing of gears with hard tooth surfaces can effectively improve the carrying capacity of the transmission device, reduce noise, reduce vibration and extend the service life. Hard finish gears are commonly used in major power transmission devices. Precision machining methods for hardened gears include gear grinding, gear scraping, gear grinding, high-speed dry cutting, gear lapping and other processes. The gear grinding process is the most widely used and mature process, with high precision and efficiency, but the cost is high and the microgeometry of the grinding tooth surface is not conducive to reduction gear transmission noise; is suitable for processing large gears with hard surface, but the precision The efficiency is not as good as that of large-scale CNC forming gear grinding With the development and maturity of gear grinding equipment at large scale, the application of gear scraping technology has been developed. gradually diminished; gear grinding is mainly used in the precision machining of bevel gear pairs; High-speed dry cutting technology has been used in the precision machining of small modular gears. Since gear honing can obtain the ideal microgeometry of the tooth surface, especially the unique texture of the tooth surface, it has a very obvious inhibiting effect on the vibration and noise of the transmission device. Therefore, the gear honing process has been applied and developed in particular. in automobile gears. Precision machining in progress.

This article summarizes the development history of gear honing technology and the latest progress in electric honing technology by the world’s leading gear machine tool manufacturers, introduces the application of new technologies and new processes in electric honing machines, and provides additional technical information on electric honing machines. . Development trends were explored.

1. Technological advancement in gear honing process

1.1 Gentle sharpening

As shown in Figure 1, traditional lapping processing uses a gear-shaped or worm-shaped lapping wheel to engage in free meshing motion with the gear to be lapped, which is equivalent to to a pair of offset-axis helical gear transmissions. and pressure between the meshing tooth surfaces are used to perform lapping, mainly used to finish the tooth surface of hardened gears. The lapping wheel is made of synthetic resin or artificial rubber with a certain degree of elasticity. In the free mesh state, the honing wheel mainly plays a smoothing role, with limited shrinkage margin, limited correction ability for gear accuracy and error reflection. The phenomenon is difficult to overcome, and the accuracy of the gear mainly depends on the accuracy of the front gear cutting and heat treatment.

Figure 1 Schematic diagram of gear sharpening processing

1.2 CBN grinding wheel sharpening hard teeth

In the 1980s, the lapping technology of hard lapping wheels was developed abroad, as shown in Figure 2. The base of the gear-shaped lapping wheel is made of medium carbon steel and an abrasive ultra-hard is applied to the tooth surface of the steel base by top electroplating. . By relying on the superabrasive present on the tooth surface of the sharpening wheel to sharpen the workpiece, the material removal capacity is improved. The rigidity of the sharpening wheel is improved. In addition to smoothing, it can also correct errors in gear tooth shape, base pitch and tooth direction, and greatly improve the precision of the gear.

Figure 2 CBN grinding wheel for sharpening teeth

1.3 Powerful gear sharpening technology

The requirements for gear precision are constantly increasing and, at the same time, more attention is being paid to surface quality. Strong gear producing countries have actively introduced advanced technologies such as electronic gearboxes, automatic loading and unloading, on-machine inspection, error correction and direct drive. , and CAM in manufacturing gear sharpening machines, and have developed unique products. The powerful gear sharpening machine series products, as shown in Figure 3, the sharpening wheel and the workpiece are forced to mesh, which has a strong ability to correct the precision of the gears. and can significantly improve the precision of gears. The precision of the powerful sharpening machine can reach DIN5 level and the surface roughness Ｒ＜0.2μm.

Figure 3 Powerful sharpening process

Gear honing technology is no longer just an auxiliary finishing process, but can be used as an independent finishing method to supplement the advantages of gear grinding technology. The development of gear honing technology is shown in Figure 4.

Figure 4 Development trend of gear honing technology

2 Benefits of powerful gear honing

As a solution for precision gear machining, gear honing has been continuously applied and developed. Powerful lapping breaks the limitation that traditional lapping can only smooth the gears, and the meshing state of the lapping wheel and the workpiece is changed. stable and stable. It is controllable, improves the stability and consistency of precision, and is more suitable for the mass production of precision gears, especially in the production of automobile gearboxes.

The advantages of power honing are mainly reflected in the following aspects:

(1) The surface texture of sharpened teeth is beneficial to reduce gear vibration and noise.

Vibration noise has always been a key evaluation indicator of precision gear transmission devices. A large number of experimental studies have proven that tooth surface texture has a huge impact on gear vibration noise, especially for high-speed transmission devices. high frequency resonance. During lapping, the lapping wheel and the gear are in a state of meshing with offset axes. The relative slip in the tooth shape direction and the relative slip in the tooth width direction combine to form a unique lapping arc pattern (as shown in Figure 5b). This model can significantly reduce gear wear. The low-noise grinding technology researched and promoted in the field of overseas gear grinding uses CNC technology, hoping to disrupt the regular grinding texture (as shown in Figure 5a) during the process. grinding and form a tooth surface texture similar to the arc pattern of sharpening.

Figure 5 Comparison of tooth surface textures between gear grinding and lapping

(2) Tooth sharpening can achieve higher surface compressive stress

The surface stress state of gears has a huge impact on gear life. Especially as the cleanliness of gear steel continues to improve, the failure mode of gears is changing from surface micro-pitting corrosion to surface micro-pitting corrosion. determines the strength and life of the gears. Gear honing can achieve higher residual compressive stress on the tooth surface, effectively improving gear strength, wear resistance and pitting corrosion resistance.

(3) Sharpening teeth can avoid burns on tooth surfaces

Tooth sharpening relies on the relative sliding of tooth surfaces to remove material. The cutting speed is low and does not produce thermal effects on the tooth surfaces, thus avoiding tooth surface burns. Grinding burn has always been an indicator that must be strictly controlled in the gear grinding process. A large amount of grinding heat changes the stress state of the tooth surface, causing microcracks and affecting the service life of the gear.

(4) Gear sharpening can achieve better tooth surface roughness

The surface quality of gears has attracted more and more attention. Compound grinding technology is also used in gear grinding to achieve grinding with low roughness values, but the processing cost increases. The gear honing processing mechanism enables it to obtain smaller tooth surface roughness value at economical cost, reaching Ra <0.2μm. Under optimized process conditions, mirror processing of the tooth surface can be achieved.

(5) Gear sharpening can process gears with shoulders

Gear grinding requires a certain amount of protrusion (overtravel), and it is difficult to process gears with stepped shaft teeth or other interference structures. Gear grinding formed with a small grinding wheel can process gears with a certain empty slot, but the grinding wheel. is small and suffers from significant wear, the grinding wheel must be replaced frequently, making it difficult to meet batch processing needs. When internal mesh sharpening is used, it is linear contact, and the entire tooth surface can be sharpened without the need to advance in the axial direction of the workpiece, and the teeth more compact shoulders can be processed.

(6) The machining accuracy of gear honing is equivalent to that of gear grinding, but the cost of gear honing tool is lower than that of gear honing. The accuracy of powerful honing can reach level 4-5, and the accuracy is slightly lower. as the precision of gear grinding. The consumption of honing wheel and coolant during gear honing process is much lower than that of gear grinding. The gear honing process can enable precision machining of gears more economically (see Figure 6 for comparison).

Figure 6 Grinding-Shaving-Sharpening Process Cost Comparison

3 Overview of the development of foreign power sharpening technology

Overseas, world-famous gear machine tool manufacturers such as Gleason-Hurt of the United States, Praewema of Germany, Fassler of Switzerland, Kanzaki of Japan and Seiwa of Japan have adopted continuous research and development , paying special attention to the needs of precision gear technology, integrating electronic gearboxes, automatic loading and unloading, on-machine inspection, error correction, direct drive, CAM and other advanced technologies have been actively introduced into the manufacturing of gear sharpening machines, and a series of powerful gear sharpening machines with unique characteristics have been developed.

(1) powerful American Gleason gear sharpening machine

Gleason in the United States launched the first generation of powerful ZH150/250 gear sharpening machines in the 1990s (Figure 7). The maximum processing gear diameter of this machine tool is 250 mm, the module is 0.5-8 mm, and the workpiece length is 350 (600) mm. In order to achieve more flexible modification, Gleason developed the spherical gear sharpening process, which provides users with a more flexible modification solution and expands the application scope of machine tools.

Figure 7 Appearance of the powerful Gleason ZH250 gear sharpening machine

In 2009, Gleason launched a new generation of powerful 150SPH gear sharpening machine (Figure 8). This machine tool directly meets the high-precision and large-volume gear processing needs of the automobile industry and is widely used in the automatic transmission industry. The maximum diameter of the machine tool processing gear is 150mm, the modulus (0.5) ~ 4mm, and the workpiece length is 150 (550)mm. The machine tool is equipped with a simpler and user-oriented operation interface and is equipped with high-speed automatic loading and unloading to meet the needs of efficient and high-volume production.

Figure 8 Gleason’s powerful next-generation 150SPH gear sharpening machine

(2) German Praweima powerful gear sharpening machine

Drawing on its rich experience in the design and manufacturing of gear machine tools, the German company Prawema has developed the powerful Synchronofine 205 HS (W) gear sharpening machine (Figure 9). The machine bed is made of natural marble, which has high vibration damping and thermal stability, ensuring stable processing quality. A major feature of the machine tool structure is the double station structure. The machine tool is equipped with two workpiece spindles. When processing the part, the next part is clamped to shorten the processing cycle. The machine tool can detect the workpiece before sharpening (Figure 10), identify the rough quality, optimize the sharpening process based on parameters such as margin and runout, and configure a measurement on machine to significantly reduce waiting time after product. tool switching or replacement.

Figure 9 Prawema Synchronofine 205HS, powerful gear sharpening machine

picture10 Check before sharpening and measurement on machine

(3) Powerful Swiss Fasler gear sharpening machine

In 1979, Fassler invented the world’s first internal gear honing machine, which has now become the HMX-400 product series (Figure 11). The HMX-400 gear sharpening machining diameter range is 50-350mm, the module range is 0.5-6mm, and the maximum workpiece shaft length is 500mm. It is easier to achieve stable machining accuracy with internal gear honing, and this form is often used in modern electric honing.

Figure 11: Powerful Fassler HMX-400 gear sharpening machine

(4) Powerful Japanese Shenqi gear sharpening machine

Japan Shenqi developed the GFB-300-NC6 gear honing machine from the beginning, and the honing wheel adopts semi-closed loop control. With the advancement of technology, the precision and quality of gear processing have been further improved. By installing a synchronous control encoder on the rotating shaft of the grinding wheel, the influence of backlash between the drive motors is reduced and the timing accuracy is improved. The product has been upgraded to GFC-α300-NC6 (Figure 12), with a processing diameter range of 50-300mm, a module range of 1-4mm, and a maximum axis length of the workpiece of 350 mm.

Figure 12: Powerful Japanese Shenqi gear sharpening machine

4 key technologies for powerful gear sharpening

Powerful gear sharpening machines are high-end precision equipment that integrate mechanical, electrical, hydraulic and instrumental instruments. Based on the understanding of foreign advanced gear sharpening machines, the following key technologies need to be overcome to develop powerful gear sharpening machines:

(1) High rigidity design of machine tools

Powerful sharpening requires a large amount of sharpening, and the sharpening wheel and the workpiece are forced to mesh, which requires maintaining a precise transmission relationship. To ensure the precision and stability of sharpening, the process system requires high rigidity and low deformation. Machine tool design should comprehensively consider static stiffness, dynamic stiffness and thermal stiffness to ensure support stability, reduce vibration caused by high-speed mesh transmission, and reduce thermal deformation of the system treatment.

(2) Sharpening wheel dressing technology

The dressing quality of the sharpening wheel directly determines the processing quality of the workpiece. The current method is to make a gear-shaped diamond dressing tool according to the workpiece parameters, and trim the tooth surface of the sharpening wheel by engaging with the sharpening wheel. . One type of part requires a special diamond dressing tool. Knives are expensive. In order to reduce costs and improve the applicability of the powerful lapping process, it is necessary to study the lapping wheel dressing technology to achieve flexible lapping wheel dressing and reduce the need for tools. special diamond dressing tools.

(3) Shift Control Technology

In order to improve the smoothness of gear movement and the uniformity of load distribution, precision gears are mostly modified, which requires the processing equipment to meet various modification requirements. Tooth sharpening relies on the relative sliding between tooth surfaces during transmission by gears with offset axes for precision machining. To achieve flexible modification, it is necessary to conduct in-depth research on the contact trajectory during the sharpening process and establish the relationship between the influence of tooth surface. movement position of the machine tool movement axis on the contact path by precisely adjusting the movement axis control to achieve flexible shaping.

5 Conclusion

The gear honing process has been widely used in the field of gear finishing with its unique advantages. During the application process, we continue to innovate and absorb the industry’s leading technological experience. The new generation of powerful lapping technology has significantly expanded the scope of. the traditional gear sharpening process, with superior precision and stability. Powerful foreign gear producing countries have accumulated rich experience in the development of CNC mechanical honing machines and the application of mechanical honing technology. Domestic gear manufacturing companies have also introduced mechanical honing equipment for technical applications. However, the development of domestic powerful gear sharpening machines is in its infancy. Currently, there are no high-end powerful gear sharpening machines for users to choose from, and they can only rely on imports. With the further promotion and application of this process and the mastery of key technologies, domestic gear machine tool manufacturers will surely launch powerful gear sharpening equipment that meets the needs of users.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: How to find peripheral alarms in the FANUC system

Great Light CNC Machining Services 29/12/2024 03:17

FANUC alarms are divided into peripheral alarms and system alarms. Peripheral alarms are alarms with alarm numbers between 1000 and 2000.

They are divided into rapid alarms and fault alarms. There are many types of system alarms, including servo alarms, spindle alarms, macro program alarms, program related alarms, etc. Typically, these alarms can be found in the FANUC maintenance manual.

As for the peripheral alarm, this is the alarm issued by the machine tool manufacturer. It can be found in the manual supplied with the machine. But if the manual is lost, how can you quickly find the cause of the alarm?

The following methods are for reference only.

As we all know, the PMC address of FANUC includes XYRKDTCA, whose address A is used to activate the alarm.

The alarm address and alarm information have the following correspondence:

That is, if address A is enabled and alarm text is available, a corresponding alarm will appear. So, when an alarm occurs, the idea to find the cause is as follows:

Now find the connected address A in PMC maintenance, then find the coil corresponding to address A in the ladder diagram, then step by step

Find the alarm activation conditions, that is, you can find the cause of the final alarm.

Some machine tool factories use a byte of address A when writing an alarm, you can first search for a byte of address A, and then find the relationship between address A and the address R corresponding to address A. The corresponding format for writing a ladder diagram is as follows:

From this statement, you can see that when each bit of R580 is connected, the alarm corresponding to A0.0-A0.7 will be triggered.

Then find out why R580.0-R580.7 is connected.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: Safety Operating Procedures for CNC Horizontal Milling and Boring Machine Workers

Great Light CNC Machining Services 29/12/2024 01:14

Safety Operating Procedures for CNC Horizontal Milling and Boring Machine Workers

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: What should we pay attention to when CNC machining box parts?

Great Light CNC Machining Services 29/12/2024 00:13

The shells are mainly used in medical cases, reducers, etc., all of which require surface treatment. On various processing surfaces, the precision of CNC machining in plane processing is easier to guarantee than the precision of hole machining. Therefore, the CNC machining accuracy of the spindle bearing hole (main hole) and the CNC machining accuracy of the box hole system are key issues in this process. For example, aluminum alloy car chassis. Good heat dissipation, high adhesion to CNC processing, four-star overlay, easy maintenance, anodized surface, five-star overlay. Disadvantages: high processing standards, relatively high costs, and difficulty in personalized style design. Wooden frames have poor heat dissipation and high-end logs are expensive. The following is a detailed introduction to the processing cases of inclined reduction box.

Several aspects must be taken into account when planning process technology.

(1) Process from surface layer to hole processing

If you process the plane from the beginning, you can not only remove the rough surface layers, but also easily draw the holes distributed in the plane to align the two ends. In addition, if the punching CNC blade is used to punch holes slowly, there will be no impact vibration or damage to the CNC blade due to uneven ports. Therefore, the floor plan should generally be addressed first.

(2) Divided into rough machining and processing links

The structure of the box is complex, and the main requirements for surface accuracy are strict. Cutting speed, clamping force and cutting heat generated during rough machining impact the precision of CNC machining. If rough machining is carried out immediately, the workpiece deformation stress caused by various reasons after rough machining cannot be fully released and cannot be eliminated during the processing process, so the shell will deform after being discharged, affecting the final precision of CNC machining of the shell. It is hoped that during the rough machining process, the tooling device can be loosened several times to release the thermal stress as soon as possible, thereby greatly guaranteeing the processing quality of the shell.

(3) Determining centralized or fragmented processes

The separation of the hull roughing and machining steps meets the requirements of a fragmented process. However, in order to reduce the number of CNC lathes and tooling fixtures used in small and medium batches and reduce the transportation and case installation time, the roughing and processing links can be relatively centralized and equipped on the same tour as much as possible. possible.

(4) Assign appropriate heat treatment methods

The structure of the forging box is complicated, the thickness is uneven, the cooling speed during forging is inconsistent, it is easy to produce thermal stress, and the surface layer is hard. Therefore, the sandblasting and quenching personnel must be scientifically organized after forging.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: HEIDENHAIN takes the sustainable development of machine tools to new heights!

Great Light CNC Machining Services 28/12/2024 23:12

In today’s pursuit of sustainable development, the machine tool industry is also actively seeking breakthroughs. As an industry leader, HEIDENHAIN is committed to reducing carbon emissions and overall cost of ownership through its exceptional innovation capabilities and future-proof solutions. “Move up the ladder, continue to develop: first qualified part, rapid production”, this is the slogan proposed by HEIDENHAIN at the next AMB trade fair in Germany in September 2024. Let’s enter the innovative world of HEIDENHAIN and discover numerous solutions for a high productivity, high quality and high process reliability.

01New HEIDENHAIN TNC7 CNC system

The new hardware of HEIDENHAIN TNC7 CNC system, including the basic version TNC7, the new generation CNC system has a wider application range, 6D MAS graphics adjustment assist function, DCM collision monitoring function and OCM cycloid milling and other functions further emphasize HEIDENHAIN characteristics and the user. conviviality. High work efficiency and high process reliability. The human-machine interface (HMI) is richer and users can now choose up to three screen sizes (24 inches, 19 inches and 16 inches) and two different keyboards. The 16-inch version of the screen, the basic version of the TNC7, can be equipped with 3+2 axis machine tools and will be unveiled at the Stuttgart trade fair. It is the successor to the TNC 620 CNC system.

02Energy consumption monitoring function and ERP interface

The new version of the HEIDENHAIN “Status Monitor” software further optimizes the function of monitoring production conditions in the workshop. The newly added energy monitoring can collect detailed data on machine tool energy consumption, compressed air and cutting fluid consumption. In order to improve the work efficiency of the digital ecosystem, a new ERP interface can automatically share data with higher-level ERP and MES systems.

03Machine tool inspection solution

The new VT 122 measuring camera and VTC software from HEIDENHAIN integrate three main functions: tool setting, tool micro-measurement and visual inspection. The vision system performs important inspection tasks, such as measuring tool wear based on images of the tool inside the machine guard, so that the machine operator does not need to send the tool to a metrology room for tedious and labor-intensive measurement. manner. Based on reliable data, the VT 122 provides a comprehensive assessment of the tool condition, saving a lot of time and increasing productivity and process reliability.

The HEIDENHAIN TD 110 tool breakage detector detects tools in the machine tool and can be seamlessly integrated into automated tool management processes. The TD 110 inspects tools as they move between the machine tool and tool magazine, saving up to six seconds of inspection time per tool change. Users benefit from longer processing time and greater process reliability.

04HEIDENHAIN True Image Technology

HEIDENHAIN’s innovative True Image technology and HEIDENHAIN machine tool scales reduce carbon emissions by up to 99%. The new grid scale effectively avoids the effects of contamination and condensation when measuring position. Linear and angle measuring systems with True Image technology from HEIDENHAIN eliminate the need for sealing air in many applications. Users benefit from a simple air seal system, reduced system costs and a lower carbon footprint of the scale.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: How to efficiently perform precision milling and grinding?

Great Light CNC Machining Services 28/12/2024 22:11

In mechanical processing, for parts with high geometric accuracy and high surface quality requirements, especially when the materials are hardened steel, cemented carbide, ceramics, silicon, germanium, quartz glass and other hard and brittle materials, a complete milling process and grinding is required. process to achieve the required treatment effect.The shape contour processing is completed by the milling process. In order to further meet the size and shape requirements of workpieces and ensure the surface effect of the workpiece, the grinding process is used to achieve high precision and high surface quality processing.

✦ Composite processing solution for milling and grinding ✦

In order to improve the processing efficiency of these parts, a composite milling-grinding processing method has appeared in the industry. By performing milling and grinding in a single device, processes are merged and process flow is reduced.

Beijing Jingdiao relies on Jingdiao high-speed grinding center to apply milling and grinding composite processing solutions to many industries. Let’s take a look at the application of Beijing composites precision engraving, milling and grinding solutions.

✦ Application file ✦

Cylindrical cam parts

machine tool:

JDGRMG500 Precision Carving Five Axis High Speed Grinding Center

Treatment effect:

+The cam groove contour surface margin is extremely poor <10μm;

+ Groove width tolerance ±10 μm;

+ Surface roughness Ra0.4 μm.

Silicone Ring Parts

machine tool:

JDHGMG800 High Speed Three Axis Precision Grinding Center

Treatment effect:

+ Cylinder capacity of the rotating surface of the part < 10 μm;

+ Surface roughness Ra0.5 μm;

+The batch processing product yield rate is 99%.

femoral condyle prosthesis

machine tool:

JDGRMG400 Precision Carving Five Axis High Speed Grinding Center

Treatment effect:

+ Surface roughness Ra0.6 μm;

+ Deviation of the contour of the articular surface ±0.05 mm;

+Cutting marks in grinding and milling parts are less than 20 μm.

Why can Jingdiao high-speed grinding center achieve such processing effects? We will give you detailed answers immediately.

✦ Exquisite carving plan ✦

01Jingdiao high speed grinding center

Jingdiao high-speed grinding center, including five-axis high-speed grinding center and three-axis high-speed grinding center, has precision milling and grinding composite processing capabilities at the micron.

Milling

Sharpening

02Jingdiao on-machine inspection system

Jingdiao’s on-machine inspection system can perform tool and workpiece measurement during milling and grinding processes.

Control of tools on machine

During milling processing, the tool length, tool radius, tool profile and other parameters are tested on the machine to ensure that the precise tool size is used for the treatment.

On-machine inspection of grinding wheels

For grinding wheels used in grinding processing, the diameter of the grinding wheel is accurately detected by the professional grinding wheel tool adjuster produced by Jingdiao to ensure that the precise diameter of the grinding wheel is used for grinding.

Inspection of parts on machine

The machine automatically performs incoming material inspection, process inspection and finished product inspection of parts to ensure that the parts are qualified as soon as they come out of the machine.

03Configuration of key components and accessories

Considering the characteristics of the grinding process in milling and grinding composite processing, it is equipped with key components and accessories developed by Jingdiao to accurately execute micron-level processing technology.

Jingdiao high speed precision electric spindle

In order to reduce the impact of the large amount of heat generated during grinding on the precision of workpieces, Jingdiao’s high-speed precision central water electric spindle is used to completely cool the grinding tools and workpieces so as to to guarantee grinding at micron level.

Jingdiao JD50 CNC system

Equipped with Jingdiao JD50 CNC system, it supports the use of different grinding tools for grinding processing.

For grinding spherical/aspherical parts, a parametric grinding programming module is also provided to improve the smoothness of grinding motion by eliminating nodes from the processing path.

Jingdiao high-speed direct drive turntable

In order to ensure the precision of workpiece grinding, a high-precision direct-drive turntable is configured to realize high-precision five-axis linkage and five-axis positioning grinding.

Jingdiao ultrasound-assisted treatment technology

In order to improve the surface quality of parts and extend the life of tools, Jingdiao ultrasonic-assisted processing technology is used. This technology is based on the professional functions of Jingdiao high-speed grinding center and JD50 CNC system, and is realized by equipping it with suitable Jingdiao self-produced ultrasonic tool holders.

Precision grinding filter system

High-precision grinding places high demands on the processing environment. Firstly, it is necessary to ensure a constant temperature of the cutting fluid. Second, it is necessary to prevent tiny abrasive particles from contaminating the cutting fluid and affecting the surface quality of the workpiece. .

Equipped with a professional filtration system for chip removal with a filtration accuracy of 5 μm, it ensures clean cutting fluid, stable temperature and smooth supply.

✦ Summary ✦

Beijing Jingdiao milling and grinding composite processing solution uses Jingdiao high-speed grinding center to perform milling and grinding of all features in one device, and uses Jingdiao on-machine detection system to measure the workpiece during processing and tool measurement, combined. With the self-developed key components and accessory configurations for milling and grinding processes, we can accurately and efficiently realize the composite processing of milling and grinding parts at the micron level.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: What is the sandblasting process?

Great Light CNC Machining Services 28/12/2024 21:09

Sandblasting process, the name may sound a little industrial, but it is everywhere in our lives. From the surface treatment of metal parts to the careful polishing of artwork, the sandblasting process plays an important role. Today, let’s take a closer look at the secrets of the sandblasting process.

The basic principle of sandblasting process is to use a high-speed jet of abrasives to impact and rub the surface of the workpiece to achieve the effects of cleaning, removing rust, increasing the surface roughness and improvement of coating adhesion. This process amounts to hitting the surface of the workpiece with countless small hammers. Through this physical effect, impurities on the surface are removed and the surface characteristics are changed.

Surface cleaning: Sandblasting can completely remove dirt, rust, paint and other impurities on the surface of an object, allowing the object to reveal its original metallic luster or background color. This cleaning method is more thorough than traditional chemical cleaning and does not damage the item itself.
Surface roughness: Sandblasting can form a uniform layer of roughness on the surface of the object. This roughness is very important for coating, bonding and other subsequent processes. This can improve the adhesion between the coating and the surface of the object, making the coating more durable.
Deburring: During machining, tiny burrs are often left on the surface of the part. These burrs not only affect the appearance, but can also affect the performance of the part. Sandblasting can effectively remove these burrs and make the surface of the workpiece smoother.
Surface reinforcement: Sandblasting can also form a hardened layer with high hardness and wear resistance on the metal surface, thereby improving the wear and corrosion resistance of the metal. This is especially important for parts exposed to harsh environments for extended periods of time.
Artistic effect: Maybe you didn’t expect it? Sandblasting can also be used to create artistic effects. Artists use sandblasting techniques to carve unique textures and patterns into hard materials, adding a unique charm to their works.

There are many types of abrasives used in the sandblasting process, including quartz sand, emery, glass beads, steel shot, etc. Different abrasives are suitable for different surface treatment needs. For example, quartz sand is suitable for removing oxide layers and rust stains on metal surfaces, while glass beads are often used for surface polishing of aluminum and stainless steel products, because their impact force is weaker and they can produce a more delicate surface effect.

Sandblasting technology has a wide range of applications. It not only plays an important role in metal surface processing, but also plays an important role in machinery manufacturing, aerospace, automobile manufacturing, electronic devices, architectural decoration and other fields. In the treatment of metal surfaces, sandblasting can remove rust, scale and old paint layers, providing a good surface base for painting and electroplating. In the mechanical manufacturing process, sandblasting is used to remove burrs and welding slag from parts and improve the surface quality and performance of parts.

The advantages of the sandblasting process are its effective cleaning, improved adhesion and versatility. It can quickly remove rust, oxide layers and contaminants on the surface, improve the adhesion of coatings and electroplating layers, and extend the service life. At the same time, the sandblasting process is suitable for a variety of materials and surface treatment needs, and has a wide range of applications.

However, the sandblasting process also faces challenges such as dust contamination, surface damage and equipment costs. A large amount of dust will be generated during the dry sandblasting process, which will affect operators and the environment, and corresponding protective measures should be taken. High pressure spraying can damage the surface of the part, requiring control of spray parameters and selection of appropriate abrasives. In addition, the cost of sandblasting equipment and abrasives is relatively high and the initial investment is large.

In actual operation, the sandblasting process requires professional equipment and precise operation. Sandblasting machines can be roughly divided into two categories: dry sandblasting machines and wet sandblasting machines. Dry sandblasting machines directly use compressed air to spray the abrasives, while wet sandblasting machines mix the abrasives and water into the mortar and then spray them. Both have their own advantages. Dry sandblasting machines are suitable for large-area, high-output operations, while wet sandblasting machines have more advantages for handling sensitive materials or preventing rust. The sandblasting machine is mainly composed of air compressor, air storage tank, spray gun, abrasive tank, control valve, connecting pipe and other components. During operation, appropriate adjustments should be made according to the requirements of the workpiece surface, including injection pressure, injection angle, injection distance, etc.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: Top 8 Reasons Why Drill Bits Fail Have You Discovered?

Great Light CNC Machining Services 28/12/2024 20:08

The drill bit can break when it enters the workpiece and, in the worst case, it can even break inside the workpiece. We can find out in this article why this happens, how it happens and how to prevent drill bits from breaking. Different twist drill bits are designed for different applications. However, even the right quality twist drill bit can break if used incorrectly.

01 The drill bit does not match the material to be processed

The most basic process involves selecting the right drill bit for the workpiece. If you use the wrong drill bit, even if you adjust other factors as much as you want, the drill bit will still break. We have compiled a list of which tool steels are suitable for which applications.

This table only gives a rough overview. For example, some high speed steel HSS drill bits are coated and can also be used in stainless steel. In addition to the tool steel, the length of the twist drill also affects its stability. The longer the twist drill, the higher the risk of breakage. Only if you need to drill deeper into the material, use a deep hole drill.

Solution: Choose the correct drill bit for the workpiece.

02 Workpiece and drill bit are not tightened enough

If the workpiece and drill bit are not properly clamped during hole machining, additional deviation may occur, which may cause the drill bit to break.

Solution: Fix the workpiece and tighten the drill bit.

03 Poor chip evacuation

The chip flutes on the drill head are used to remove chips. The wider the groove, the better the chip evacuation effect. If the chips cannot be ejected, the bit may jam and fall. Poor chip evacuation results in additional heat generation, which can lead to annealing and ultimately drill breakage.

Solution: Use coolant and lubricant to repeatedly push the bit out of the workpiece to facilitate chip evacuation.

04Cutting speed and feed settings are incorrect

If you are using a vertical drill, make sure you choose the correct speed and feed, otherwise the drill bit may break.

Solution: Refer to the cutting speed parameter table and adjust the corresponding speed and feed.

05The quality of the drill is poor

If the twist drill bit is worn it will break, which is a manufacturing defect and could be due to poor quality steel or lack of sharpness.

Solution: Use the correct drill bit for the application.

06 Small/large diameter twist drill

Small diameter twist drills are very sensitive. You can break them with your hands.

Solution: For small diameter drill bits, be sure not to push too hard. For large diameter drill bits such as 16mm, be sure to use two or three smaller twist drill bits for pre-drilling. Drilling directly into the workpiece material places stress on the bit and can cause breakage.

Solution: Pre-drill the hole and remove the drill bit from the workpiece several times (chip removal).

07No cooling

As mentioned earlier, very high temperatures are generated during the drilling process. If you work too long without stopping to let the bit cool, thermal cracks can develop.

Solution: Use a lubricating coolant to cool and repeatedly remove the drill bit from the workpiece to remove chips.

08Use a hand drill instead of a drill press

Some drill bits are only suitable for use in drill presses because they allow maximum control of feed and cutting speed. You can also perform drill guidance.

The harder the material of the drill bit, the more fragile it is and the easier it is to break. Solid carbide drill bits are very hard and must be used with a drill press.

Solution: Choose the right drill press.

in conclusion

Twist drill bits are designed for a variety of applications. Depending on whether you are drilling a hole in structural steel or high-strength steel, you need to choose the appropriate drill bit. If you don’t do this, the bit could break.

We’ve listed eight reasons why drill bits break:

1. Using a drill bit unsuitable for the material to be processed

2. Insufficient tightening of workpiece and drill bit

3. Poor chip removal

4. Cutting speed and feed rate settings are incorrect

5. Poor drill quality

6. Small/large diameter of twist drill

7. Not enough cooling

8. Use a hand drill instead of a post drill

If you notice these issues, your drill bit should be in good condition and capable of handling long-term processing requirements.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: Professor Zhu Xiaolu – Regarding the problem of wear of the hardened layer of the tooth base of hardened gears

Great Light CNC Machining Services 28/12/2024 18:06

question:

A friend from a northern company asked: If the hardened layer of the hard surface gear tooth root is worn, will it have a significant impact on the bending strength of the gear teeth? ‘gear ?

answer:

1. The impact of hardened layer of hard surface gear tooth root on the bending strength of gear teeth.

The hardened layer of the hard surface gear tooth root has been worn away. This situation belongs to excessive wear of the gear teeth. Its specific manifestations include large wear of the working tooth surface material and changes in the tooth surface material. the size of the gear teeth, which of course greatly affects the bending resistance of the gear teeth, the main reasons are:

(1) Excessive wear reduces the load-bearing cross-sectional area of the tooth root. Figure 1 shows an example. The dimensional changes of gear teeth after excessive wear are shown in Figure 2. The load size S’ after wear is smaller than the normal load size S, and the bending resistance of the gear teeth will decrease inevitably.

(2) When the hardened martensite layer on the tooth root of the hardened tooth surface is worn away, the residual compressive stress in the tooth root returns to zero, and even residual tensile stress appears, which which is very detrimental to the bending resistance of the gear teeth.

(3) Excessive wear destroys the normal shape of the tooth profile, resulting in significant vibration and noise of the gear system, a sharp increase in dynamic load, and ultimately random breakage of the gear teeth. gear.

(4) Conclusion: Generally, these gears should be scrapped.

Figure 1 Example of excessive gear tooth wear

Figure 2 Gear tooth dimensions after excessive wear

2. Failure criteria for excessive gear tooth wear

The failure criterion of gear tooth wear is the degree of wear of the gear teeth before the gear can be scrapped. There are two failure criteria for gears: one is the failure criterion for gear bench testing and the other is the failure criterion for industrial product gears. The former is clearly specified in GB/T 3480-1997 “Method for calculating the load capacity of involute cylindrical gears”. It is not suitable for actual product gears in different industries and different working conditions (such as automobile gears, aviation gears, machine tool gears, ship gears, etc.), because the use of these gears is much more complicated than test gears, and it is impossible to formulate product gear failure criteria common to all industries and working conditions. The feasible method is to formulate gear failure criteria consistent with actual industry conditions through a large number of surveys, analysis, calculations and experience summaries based on the actual conditions of each industry.

The following content is taken from JB/T 5664-1991 “Heavy Load Gear Failure Criteria”. See:

Editor-in-chief Zhu Xiaolu. Gear Transmission Design Handbook.[M].Beijing: Chemical Industry Press, 2010: 73-74.

3. Discussion

(1) JB/T 5664-1991 “Heavy load gear failure criteria” is mainly formulated on the basis of industrial practical experience and lacks rigorous theoretical analysis basis. For example, the standard believes that excessively worn gears can be calculated using GB/T 3480-1997 for the bending strength of gear teeth. However, the determination of the tooth profile coefficient in the calculation will encounter difficulties in the theoretical analysis.

(2) The rationality of using the bearing dimension S’ after wear to calculate the bending resistance of gear teeth is also questionable. It would be more reasonable to use the dimension S’ in Figure 2.

(3) The lubrication system fails, the sealing device is poor, and the oil film cannot be established; the transmission system has high vibration and impact loads, which will cause excessive wear. Particularly on open gear transmissions, excessive wear is common.

(4) Excessive wear of closed gear transmissions with hard tooth surfaces is rarely observed, but when the gear pitch speed is less than 0.5 m/s and it is impossible to establish a oil film, excessive wear may also occur.

(5) The failure criteria and strength calculation of excessively worn gears are still far from perfect and there is still room for further research, which could be studied as a special topic.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: Machining precision control method of CNC lathes

Great Light CNC Machining Services 28/12/2024 17:04

Generally pay attention to the following points: tool wear, elastic deformation of the workpiece, processing technology, processing sequence, tool adjustment, tool compensation change, machine tool clearance status , tightening method, etc.

1. CNC lathe processing optimization parameters, balance the tool load and reduce tool wear. Due to the differences in their own geometric shapes, there are large differences in rigidity and strength between different cutting tools, for example between a straight cylindrical cutter and a cutting cutter, and between a straight cylindrical cutter and an inverted cylindrical cutter . If these differences are not taken into account during programming. Using a tool with low strength and rigidity to support a large cutting load will cause abnormal wear and even damage of the tool, and the processing quality of the parts will not meet the requirements. Therefore, the workpiece structure must be analyzed during programming to reduce the number of sharpening times and tool replacements.

2. The processing technology of CNC lathe is similar to that of ordinary lathe. However, since the CNC lathe is clamped once and performs all turning processes continuously and automatically, the following aspects must be considered:

(1) Choose the cutting quantity reasonably.

For high-efficiency metal cutting, the material to be processed, cutting tools and cutting conditions are the three main elements. These determine the machining time, tool life and machining quality.

The three elements of cutting conditions: cutting speed, feed and cutting depth directly cause damage to the tool. As the cutting speed increases, the temperature of the tool tip increases, causing mechanical, chemical and thermal wear. If the cutting speed is increased by 20%, the tool life will be reduced by 1/2.

The relationship between feed conditions and reverse tool wear is in a very small range. It has less impact on the tool than the cutting speed. Although the impact of cutting depth on the tool is not as great as that of cutting speed and feed, when cutting with a small cutting depth, the cut material will produce a hardened layer , which will also affect the tool life. .

The user should choose the cutting speed according to the material to be processed, hardness, cutting condition, material type, feed amount, cutting depth, etc. The most suitable processing conditions are selected based on these factors. However, in actual operations, the choice of tool life is related to tool wear, changes in machined dimensions, surface quality, cutting noise, heat treatment, etc. For difficult-to-machine materials like stainless steel and heat-resistant alloys, you can use coolant or choose a rigid blade.

(2) Choose tools reasonably.

(a) When rough turning, you should choose tools with high strength and durability to meet the requirements of large back cut and large feed during rough turning; (b) When finishing turning, you should choose tools with high precision and durability. good tools to ensure machining precision requirements; (c) In order to reduce tool change time and facilitate tool adjustment, machine-clamped tools and blades should be used wherever possible (d) Try to use universal clamping devices; workpieces and avoid using special accessories.

(3) Determine the treatment route.

Machining route refers to the path and direction of movement of the tool relative to the workpiece during the machining process of the index control machine tool.

(a) Processing precision and surface roughness requirements must be guaranteed; (b) The processing route should be shortened as much as possible to reduce tool idle time; (c) The relationship between the processing route and the machining allowance;

At present, because CNC lathes are not yet widely used, the excess margin on the blank, especially the margin containing forged and cast hard layers, should generally be processed on ordinary lathes. If it is necessary to use a CNC lathe for machining, you should pay attention to the flexible layout of the program.

(d) Key points for device installation At present, the connection between the hydraulic chuck and the hydraulic clamping cylinder is made by a tie rod. The key points for tightening the hydraulic chuck are as follows: First, use a wrench to remove the. nut on the hydraulic cylinder, remove the draw pipe and remove it from the hydraulic chuck. Remove the rear end of the spindle, then use a handle to remove the chuck retaining screws to remove the chuck. The tool wiper edge refers to a small section of the blade that is ground parallel to the tool tip in the direction of the secondary deflection angle behind the tool blade. It is mainly used for primary cutting and secondary cutting after cutting. The blade. This is equivalent to the finishing process to remove burrs and other scars. Improving workpiece surface roughness is mainly used on finishing tools.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: An introduction to the benefits of spot welding (RSW) and its application in automotive body blank welding

Great Light CNC Machining Services 28/12/2024 16:02

Resistance spot welding (RSW) is a widely used welding technology in industrial production. It has the following advantages over other welding technologies:

The metallurgical process is simple: during spot welding, the molten nugget is formed and surrounded by a plastic ring, and the molten metal is isolated from the air, which simplifies the metallurgical process.

Short heating time: the heat is concentrated, the heat affected zone is small, the deformation and stress are also small, and subsequent correction and heat treatment processes are generally not required.

High cost-effectiveness: Spot welding does not require filler metals such as welding wires and electrodes, nor welding materials such as oxygen, acetylene and argon, reducing welding costs welding.

Easy operation: Spot welding is simple to operate, easy to implement mechanization and automation, and improves production efficiency and working conditions.

Environmentally friendly: There is no noise or harmful gas emissions during the spot welding process, suitable for modern factory environments.

Suitable for a variety of materials: Spot welding is suitable for different thicknesses and types of metal materials, including aluminum alloys and galvanized steel, etc. These materials may require special welding techniques.

Fast welding speed: Spot welding has fast welding speed, is suitable for mass production, and can be integrated into the production line with other manufacturing processes.

Controllable welding quality: By controlling the welding current and pressure, high-quality welding joints can be obtained, and the spot-welded joints have better mechanical properties.

These advantages of spot welding technology make it widely used in automobile manufacturing, electronic equipment, household appliance manufacturing and other fields.

Automotive body blank spot welding is a high-quality, high-efficiency, low-cost welding technology widely used in the automobile industry. Spot welding uses the electrodes to heat resistance heat generated by overlapping metal parts, causing the parts to be welded to partially melt and then solidify to form a strong weld joint. This welding method is suitable for wire welding, welding of stamping structures and welding of thin plates. It is one of the main welding processes to connect body parts in white.

Key points in the spot welding process include the selection and control of parameters such as welding current, electrode pressure and power-on time. These parameters directly affect solder joint quality, including strength, nugget size, and solder joint appearance. In actual production, according to the parts with different thicknesses and welding requirements, different welding specification parameters will be selected and corrected through specimen peeling experiments. In addition to the above three main parameters, the electrode shape, electrode pressing method, welding method, etc. are also required. will also affect the quality of welding. Reasonable selection and optimization of these parameters are equally important for the quality and performance of welded joints.

Spot welding quality control is the key to ensuring the structural strength and safety of automotive bodies in white. Quality control measures include dynamic monitoring of strength curves during the welding process, application of adaptive control technology and non-destructive testing technology after the weld joint. These technologies help improve the qualification rate of weld joints, reduce quality defects, and ensure that welding quality meets the strict standards of automobile manufacturers.

With the application of new materials and the development of automatic digital technology, spot welding technology is moving in a more intelligent and efficient direction. For example, laser spiral spot welding technology offers the possibility of replacing traditional resistance spot welding and can achieve good weld formation and mechanical properties of joints in the case of single-sided welding. In addition, the introduction of automated spot welding production lines has also improved production efficiency and welding quality consistency.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: Detailed explanation in an article: Ultra-precision magnetorheological machine tools

Great Light CNC Machining Services 28/12/2024 15:01

Industry Briefing

With the rapid development of science and technology and the widespread application of ultra-precision equipment such as precision instruments and equipment, increasingly higher quality requirements have been put forward for key optical components optical systems. The shapes have been improved compared to the original plan. , spherical and cylindrical. The accuracy of aspherical surfaces, aspherical cylinders, free-form surfaces, etc. has also been improved from the original RMS1/30~1/50λ (1λ=632.8 nm) to RMS1/100~1/ 200λ.

Nowadays, most of my country’s optical manufacturing and processing still rely on traditional processing methods, such as double-sided polishing, annular polishing and multi-axis polishing.

This type of process is mainly applied to flat, spherical and cylindrical surfaces and has the advantages of low equipment cost and good batch performance. However, it is insufficient when dealing with optical components such as aspherical surfaces, free-form surfaces, large sizes. -size thin-walled parts, etc. At the same time, the traditional processing time of this method is relatively long, it largely relies on master craftsmen, and its controllability is relatively poor, making it difficult to meet the needs of customized and complex ultra-precision optical components on the market.

The main CNC polishing methods currently widely used in polishing ultra-precision optical components include:

Different polishing methods are available, including CCOS, SLP, FJP, IBF, Bonnet Polishing and MRF. Their corresponding processing characteristics have their own strengths. Helpline: 13522079385

Magnetorheological polishing technology:

It uses the rheological characteristics of magnetorheological fluid in a magnetic field to polish the surface of optical components.

When no magnetic field is applied, the rheological properties of the magnetorheological fluid are similar to those of ordinary Newtonian fluids. When the magnetorheological fluid is subjected to a strong magnetic field, the viscosity and hardness of the magnetorheological fluid increase significantly and become similar. to a “solid” convex state forms a “flexible polishing mold”, which achieves flexible shrinkage mainly based on shear stress under the driving of the polishing wheel.

Since the viscosity and hardness of the magnetorheological fluid can be kept constant by controlling parameters such as magnetic field and flow rate, the removal function of magnetorheological polishing technology has extremely high stability and controllability. In long-term treatment, the elimination function The size. and the removal efficiency can remain unchanged, and its impact is very small compared with problems such as abrasive wear and polishing matrix deformation that occur in traditional polishing.

It is because of these properties that MRF is used as a deterministic processing technology.Widely used in high precision modification stage of optical components, RMS can reach 1/200λ。

At the same time, during processing, shear removal is mainly used. The normal processing stress is low and almost no underground damage is caused to the optical elements. Even when facing a part with a high diameter-to-thickness ratio, the processing residual stress is. small and no processing will occur. Deformation, high adaptability, good processing surface quality, rapid convergence, high precision and other processing characteristics.

Schematic diagram of magnetorheological treatment process

Magnetorheological polishing machine tools, machine tools mainly use natural marble bases, which have the characteristics of high stability, good impact resistance and high precision of the body surface. Magnetorheological machine tool equipment can guarantee long-term high-precision operation and can meet the needs of. Ultra-precision machine tools for high-precision processing of various types are required. Marble countertops have a low coefficient of thermal expansion and are not prone to warping.

The magnetorheological polishing machine tool can realize six-axis linkage of X, Y, Z, A, B and U. It is driven by servo motor, ball screw and linear guide. It has high working positioning precision, good robustness and. stable error suppression effect. The optional movement stroke of each axis can process workpieces with a maximum size of φ3000mm, and supports equipment customization at the same time, to adapt to the curvature and processing efficiency of the different polishing components, Tianchuang now offers 5; polishing types Polishing wheels: φ20mm, φ50mm, φ100mm, φ200mm and φ340mm are available for customers to choose from. The diameter of the polishing wheel is closely related to the polishing efficiency and the curvature of the workpiece. the higher the processing efficiency, the smaller the curvature range to which polishing is suitable. Guang, in terms of equipment selection, customers are generally recommended to select several polishing wheels of different specifications according to the characteristics of their own processed parts.

Magnetorheological Polishing Ultra-Precision Machining Machine Tools

At the same time, customers can freely choose from a variety of magnetorheological fluids according to their processing needs. The material processing range covers: single crystal silicon, nickel, aluminum, ordinary glass, fused quartz, silicon carbide and other materials, with roughness. Ra down to 0.5 nm.

Application case

Magnetorheological polishing technology is widely used in the ultra-precision manufacturing of optical components of various shapes and properties, meeting the needs of ultra-precision processing of optical components in aerospace, ultra-precision optical device equipment, devices optoelectronic, electronic and domestic information industry. defense industry.

Magnetorheological polishing technology can realize nano-precision processing of optical components. The processing precision of Tianchuang Seiko’s magnetorheological machine tools can reach RMS1/200λ (λ=632.8nm), and the surface roughness Ra is better than 0.5nm. It is used in the field of high-precision processing of planar, spherical, cylindrical, aspherical and free-form surfaces with a large diameter/thickness ratio, and can meet the needs of very high-precision optical components in the fields of Aerospace, ultra-precision optical device equipment, optoelectronic devices, electronic information industry and national defense industry.

Here are some classic cases:

(1) fused quartz optical element D100 mm

The component is only 5mm thick, with a diameter-to-thickness ratio of 20. The PV of the incoming material is 1/2λ, and the design requires a PV of 1/20λ. Finally, after 40 minutes of treatment, the component is obtained. the effective diameter has a PV of 30.58 nm (<1/20λ), RMS3 0.59 nm (<1/170λ).

(2) Microcrystalline components

The left image shows the processing result of the D350mm microcrystalline plane mirror. The RMS is 6.14 nm and is better than 1/100λ. The piece has obvious power before processing. Its PV value is 4 um. processing hours. It can be used as optical inspection. Use a compensating mirror. The right image is an aspherical microcrystal after processing, the effective diameter is RMS6.665 nm (about 1/100λ).

(3) Aspherical silicon mirror

Single crystal silicon has high thermal conductivity and low thermal expansion (not easily deformed in high-energy light paths), and it is easy to process cooling structures such as micro-grooves, so it is widely used in high energy lasers. At the same time, due to its good infrared transmission, it is widely used in various infrared optical guidance systems. Magnetorheology has the ability to process and sample single crystal silicon, and the RMS of aspherical processing of single crystal silicon can reach 1/50λ.

(4) Aluminum mirror processing

Aluminum has the characteristics of light weight, high reflectivity and good processability. It can be used in optical-mechanical integration design. It is also used in laser radars and various optical systems. Magnetorheology can be used to process aluminum mirrors, and its RMS processing accuracy can reach up to 1/70λ.

Conclusion

For the field of ultra-precision optical processing, the emergence of magnetorheological polishing technology constitutes a key technological advancement. Compared with other polishing technologies with nanometer-level processing precision, it has high removal efficiency, good stability of removal function and smooth processing surface. It has the advantages of excellent quality, high adaptability to workpiece materials, and almost no surface and subsurface damage. It can stably and reliably realize ultra-precision processing of optical components. It is widely used in many fields such as optics and instrumentation. , laser radar and space imaging. It has high market value and broad application prospects.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: The lenses of ASML lithography machines are milled by machine tools, then polished with small grinding heads, magnetorheological polishing and ion beam polishing to achieve the required precision.

Great Light CNC Machining Services 28/12/2024 14:00

The lenses for ASML lithography machines are manufactured by Carl Zeiss in Germany. The mirror blanks are first milled and shaped by high-precision machine tools, and then ultra-precision polishing methods such as small grinding head polishing, magnetorheological polishing and beam beam polishing ions are used. To achieve the required accuracy, the coating is finally applied (for DUV lenses, it is covered with an anti-reflective coating; for EUV lenses, it is covered with a reflective multi-layer coating).

The basis of ultra-precise optical lens processing is numerically controlled optical surface shaping (CCOS) technology, which replaces control by human experience with computer automation control.

Small grinding head polishing technology uses a grinding head much smaller than the diameter of the workpiece to polish the workpiece. The amount of material removed is controlled by controlling the residence time of the grinding head at different positions on the workpiece surface and the pressure. between the grinding head and the workpiece. Able to achieve processing precision of tens of nanometers.

The most advanced technology is strain disk polishing, that is, the polishing disk can be deformed in real time according to the shape to be processed under computer control to achieve complete fit between the disk of polishing and the part.

Next comes magnetorheological polishing (magnetorheological finishing, MRF), which uses a special polishing fluid with a magnetorheological effect as a polishing material. This type of polishing fluid contains non-magnetic polishing powder and magnetic iron powder, which behaves like a conventional liquid state in the absence of a magnetic field. Under the action of a magnetic field, the iron powder is oriented and arranged in such a way as to allow polishing. the fluid has properties similar to those of a solid.

The magnetorheological polishing fluid is adsorbed on the polishing wheel with a magnetic field and contacts the workpiece when the polishing wheel rotates, thereby removing excess material from the workpiece surface. This is equivalent to using a flexible grinding head. Its shape and hardness can be precisely controlled in real time through a magnetic field, and it always fits the workpiece surface closely. It has high processing efficiency, stable processing process, high processing precision. and good surface quality (no surface and subsurface damage), which can improve accuracy down to the nanometer level.

Finally, thanks to ion beam polishing technology (Ion Bean Figuring, IBF), the precision of the lens is improved down to the sub-nanometer level (atomic scale).

Under vacuum conditions, an electric field is used to ionize inert gases such as argon into ions, which bombard the surface of the part to remove surface atoms. It is an atomic-scale processing method with good processing precision and stability. There is no mechanical contact with the part and no surface damage. It is currently the most advanced optical element processing technology. However, the processing efficiency of ion beam polishing is low, and it is usually used as the last means of precise modification.

The National University of Defense Technology uses an independently developed ion beam polishing machine tool to process lenses used in DUV lithography machines.

Precision processing requires corresponding measurement methods to guide. In the rough grinding and polishing stages, a swing arm profiler (left in the image above) is commonly used, using a high precision displacement sensor installed at the end of the rotating arm to measure the profile surface of the mirror blank, with a precision ranging from microns to tens of nanometers. In the precision polishing stage, the optical interference method (right in the image above) is used to measure the shape of the lens surface with high precision.

Attachment: There are many articles on the Internet stating that the German company Zeiss uses the German ALZMETALL GS-1400 heavy-duty precision five-axis vertical cradle machine tool to directly process the lenses of the EUV lithography machine with an accuracy of 20 picometers (0.02 nanometers). . There are also rumors mentioned in the messages. I was suspicious of it, checked it out and decided it was misinformation, hence this post.

Zeiss uses precision machine tool milling to process lithography machine lenses, but it also has to go through small grinding head polishing, magnetorheological polishing, and ion beam polishing (all based on advanced technology). of computer-controlled optical surface shaping, so information from Zeiss This is called computer-controlled polishing) to achieve a surface precision of 0.12 nanometers and an effective value of 0.02 nanometers.

For advice on various polishing equipment, please call: 13501282025

Misinformation may come from misunderstanding this PPT from Zeiss:

This PPT mentioned the processing precision of the objective lens of the new generation EUV lithography machine, but only the GS1400 machine tool was given in the processing method, so it was wrongly thought that this machine tool was used to process the object lens with final precision in one shot. In fact, the “ground” in the “First Mirror Bottom” marked on the lens displayed on the PPT is the past participle of “grind”, which means “grinding”, that is, the lens was only ground by machine. tool, then needs to be polished, or “finishing” (finishing, figuring) can achieve the final atomic precision, which is beyond the reach of machining machine tools.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: Precision compensation measurements in machine tool machining

Great Light CNC Machining Services 28/12/2024 11:57

(1) Backlash compensation

In the transmission system of CNC machine tools, the servo motor and screw are generally connected in three ways: direct connection, synchronous belt transmission and gear transmission. Gears, ball screws, nuts, etc. The existence of this backlash will cause the servo motor to idle and the workbench will not actually move when the machine tool table moves in reverse, or when the servo motor moves. but the measuring device does not detect the displacement. For CNC machine tools, backlash will affect the positioning accuracy and repetitive positioning accuracy of the machine tool, thereby affecting the accuracy of processed products. This requires the CNC system to provide a software backlash compensation function to compensate for machine tool backlash, reduce its impact on machine tool accuracy, and improve the accuracy of machined parts. Often, as the use life of CNC machine tools increases, the backlash gradually increases due to the wear of mechanical parts. Therefore, the backlash of each coordinate axis of the CNC machine tool should be measured and compensated regularly.

(2) Pitch compensation

The linear feed axis on CNC machine tools mainly uses ball screws as mechanical transmission components. The motor drives the movement of the ball screw and converts the rotational movement of the motor into the linear movement of the feed shaft. If there is no error between the pitches of the ball screw, the rotation angle of the ball screw is linearly related to the linear displacement of the corresponding feed axis. However, in practice, there are always errors in both the manufacturing process and assembly, and there is a pitch error with each pitch of the ball screw. The linear movement of the feed axis is also reflected in a certain error, which will reduce the machining precision of the machine tool. Most CNC systems provide a pitch error compensation function, which can compensate for the pitch error that occurs in CNC machine tools to reduce machine tool errors and improve the accuracy of the machine tool. ‘machining. In addition, after a long time use of a CNC machine tool, due to the different wear degrees of each ball screw pitch, the error between each pitch will further increase, resulting in a decrease in the machining precision of the machine tool. Through periodic calibration and error compensation of machine tools, the life of machine tools can be extended while maintaining precision.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: Research and application of laser welding of sheet metal

Great Light CNC Machining Services 28/12/2024 10:55

As an important processing technology in sheet metal processing, welding is labor-intensive, has a harsh working environment and requires high skills. Therefore, automation of welding technology and new welding methods have always been the focus of technicians’ research. The key to achieving welding automation lies in the effective control of quality and efficiency, which requires solving problems such as centering the arc and weld beads, uniform gap between parts, weld penetration and weld distortion control.

With the rapid development of laser welding technology, this technology has been widely used in many fields. In the fields of household appliances, high-tech electronics, automobile manufacturing, high-speed train manufacturing, precision processing, etc., laser welding technology has demonstrated its unique advantages. The emergence of this technology not only changes the traditional welding method, but also greatly improves welding efficiency and precision. With the continuous development of science and technology, welding technology is also constantly improving. From the initial manual welding to today’s automated welding and new welding methods, welding technology has made a qualitative leap.

Features of laser welding

Laser welding uses a laser to couple a high-energy laser beam into an artificial optical fiber. After transmission, it is collimated into parallel light through a collimating mirror, then focused onto the part, bringing it together into an extremely high energy heat source. density, melting the material at the joint, then the liquid metal quickly. The welding method to form a high-quality weld after cooling is shown in Figure 1.

Figure 1 Laser welding

Easy to use and learn

The laser welding equipment has a simple structure, it is easy to learn the operation process, and it is easy to operate. The professional requirements of welding operators are not high, which can greatly reduce labor costs.

Micro-welding possible

The laser beam can get a very small spot after being focused and can be precisely positioned. It can be applied to assembly welding of micro and small parts in automated mass production.

Great flexibility

The laser welding machine can achieve welding at any angle, weld inaccessible parts, and can also weld various complex parts and large parts with irregular shapes, achieving welding at any angle and has high flexibility.

Good welding effect

The surface of the parts after laser welding is smooth, does not need to be polished, has no black edges, and no weld scars has any defects such as pores, cracks, undercuts or subsidence. the seam is more beautiful and smoother than ordinary second-hand protective welding and argon arc welding.

Strong safety performance

The high-security welding tip can only touch the switch when it comes into contact with metal, and the touch switch has body temperature detection. Special laser generators have safety requirements during operation. The operator should wear protective glasses for the laser generator to reduce eye damage.

High laser quality

Once the laser is focused, the power density is high. After the high-power low-order mode laser is focused, the focal spot diameter is small, which greatly promotes the development of automated thin plate welding.

Fast welding speed, large depth and small deformation

Laser welding has high power density. Small holes are formed in the metal material during the welding process. The laser energy is transmitted deep into the workpiece through the small holes with less side scattering, the material melting depth is greater during the laser beam scanning process. ; the speed is fast and the welding unit time is large area.

Manual welding is inexpensive

The heat input of laser welding is extremely small, the deformation after welding is very small, the welding slag is small, and the welding slag has no spatter. It can achieve a very beautiful welding effect on the surface. is less, which can reduce or eliminate subsequent polishing and leveling processes incurred.

Welding difficult-to-weld materials

Laser welding not only can weld a variety of different metal materials, but also can be used to weld titanium, nickel, zinc, copper, aluminum, chromium, niobium, gold, silver and other metals and their alloys, as well as steel, Kovar. Alloy and other materials. It can well meet the development and application of new materials for household appliances.

Suitable for welding thin plate parts without sprayed appearance

The laser welding machine has a high welding aspect ratio, a low energy ratio, a small heat-affected zone and a small amount of welding deformation. It is particularly suitable for welding parts with an unsprayed appearance made from thin, heat-sensitive plates. parts, which can reduce post-welding corrections and secondary processing.

Comparison of the advantages of laser welding

Laser welding can be divided into heat conduction welding and laser deep penetration welding according to the formation characteristics of the weld during welding. Heat conduction welding uses low laser power, the molten pool formation time is long and the penetration depth is shallow, and it is mainly used for welding small parts; deep penetration welding has high power density, the metal melts quickly in the laser radiation area, and the metal melts with strong vaporization, can obtain welds with greater penetration depth and weld width ratio can reach 10:1. The optical fiber transmission laser welding machine is equipped with an optional CCD camera monitoring system to facilitate observation and precise positioning; its welding point energy is evenly distributed and has the best point required for welding characteristics. It is suitable for various complex welds and spot welding; of various devices, complete welding and continuous welding of thin plates within 1mm.

The main factors affecting laser welding are beam characteristics, welding characteristics, shielding gas, material characteristics and welding performance. ⑴ Beam characteristics include laser, optical configuration, etc. ; ⑵ Welding characteristics include welding joint shape, weld distribution, assembly accuracy, welding process parameters, etc. ; ⑶ Shielding gas includes type, flow rate, shielding force type, etc. ; gas ; ⑷ Main material characteristics The wavelength and material of the laser This is related to the properties, temperature and surface conditions of the material. Most materials have higher absorption rates for short wavelength lasers. Materials have lower laser absorption rates at room temperature, and absorption rates increase sharply as temperature increases. (5) The welding properties of materials include thermal conductivity, thermal expansion coefficient, melting point, boiling point and other properties.

Compared with traditional manual argon arc welding or gas shielded welding, laser welding uses the latest generation of fiber lasers and is equipped with self-developed welding heads. It has the advantages of simple operation, beautiful welds, fast welding speed and no consumables. .It is used in stainless steel plates, iron. In terms of welding metal materials such as plates, galvanized plates, aluminum plates, etc., it can perfectly replace traditional argon arc welding, electric welding and other processes. The comparison of argon arc welding beads and laser welding beads of sheet metal parts is shown in Figure 2.

Figure 2 Comparison of Argon Arc Welding Beads and Laser Welding Beads

There are many commonly used welding methods for thin plates, such as laser welding, electron beam welding, argon arc welding, resistance welding, plasma arc welding , etc. Compared with other commonly used welding methods, laser welding has poor performance in the heat affected zone. , depth ratio and weld bead. It has great advantages in cross-sectional morphology, ease of operation, automatic processing and labor costs. The comparison between laser welding and other welding methods is shown in Table 1.

Table 1 Comparison between laser welding and other welding methods

Note: “√” indicates benefits; “×” indicates disadvantages; “0” indicates moderate.

Setting up the laser welding process

The key to laser welding equipment lies in setting and adjusting process parameters. Select different scan speeds, width, power and other values depending on the material thickness and workpiece material (duty cycle and pulse frequency are usually not necessary). be changed), as shown in Figure 3, the common process parameters are shown in Table 2.

Table 2 Common process parameters table

Figure 3 Process parameters of laser welding equipment

⑴ The process interface contains the parameters of the debugged process, which can be changed by clicking the box. After editing, click OK, then save it to the quick process, and click to import when using it ⑵ The scanning speed range is 2~; 6000mm/s and the scanning width range is 0-5mm. Scan speed is limited by scan width. The limit relationship is: 10 ≤ scanning speed / (scanning width × 2) ≤ 1000. If the limit is exceeded, it will automatically become the limit value. When the scan width is set to 0, there will be no scan (i.e. point light source) (most commonly used scan speed: 300 mm/s, width 2.5 mm (3) The maximum power must be less than or equal to ); laser power on the settings page; (4) Duty cycle range is 0-100 (default 100, usually no need to change); ⑸ Recommended pulse frequency range 5~5000Hz (default 2000, usually no need to change).

Different material thicknesses and materials have different welding powers. Laser power is the maximum power of the laser used. When the light is turned on, the processing power gradually increases from N1 to 100%; when the light is turned off, the processing power gradually increases from 100% to N2, as shown in Figure 4.

Figure 4 Schematic diagram of laser power

Application of laser welding equipment

The welding equipment in our commercial welding workshop includes: Panasonic YC-315TX argon arc welding machine, Panasonic YC-300WX argon arc welding machine, welding machine with protection Miller carbon dioxide, Jiashi WF-21 carbon dioxide protection welding machine, OTC carbon dioxide. Gas shielded welding machine and MIG welding machine, etc., as shown in Figures 5, 6 and 7.

Figure 5 YC-315TX Argon Arc Welding Machine

Figure 6 Jasic WF-21 welding machine with gas protection against carbon dioxide

Figure 7 OTC gas shielded welding machine with carbon dioxide

According to the production capacity of our single workshop, we can reduce the personnel investment of 3 people in welding and grinding operations, reduce the overall deformation by 20%, reduce the grinding workload by 30%, improve overall welding quality by 20%, and increase welding efficiency by 50%. After checking the quality of the product process and verifying the production operations, the laser welding machine can completely replace the traditional welding machine, and the effect is very obvious. As our company’s products involved in the fields of bus air conditioners, intelligent railway air conditioners and high-end home appliances began to emerge, in order to meet customers’ requirements for lightweight units and high-quality materials. range, only light and powerful welding can fully meet the requirements. welded connections of structural parts of these units. This is something that traditional welding cannot achieve.

Conclusion

Welding technology is an important cornerstone for my country to become a major manufacturing country. Today, almost all fields, such as machine manufacturing, petrochemical industry, transportation, energy, metallurgy, electronics, aerospace, etc., are inseparable from supporting technology. welding. The new generation of welding technologies, represented by electron beam welding and laser welding, are increasingly used. Considering the factors of environmental protection and operating costs, laser welding has many advantages such as high power density, no electrode pollution, no contact, low machine loss and tool, is not affected by magnetic fields and can accurately align welds. Therefore, laser welding is the development trend of future welding, which also requires enterprise technicians to put forward better and higher application-level requirements to encourage laser welding machine enterprises to move forward together .

Text/Lu Changshui, Tan Xiaoyu, Huang Qicun, Wang Haosong·Zhuhai Gree Electric Co., Ltd. Sheet metal spraying branch factory

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: What is a small grinding head polisher (CCOS)

Great Light CNC Machining Services 28/12/2024 09:53

Small grinding head polishing machine (CCOS) is an advanced process method that combines traditional grinding and polishing experience with modern CNC technology. It is used to process aspherical optical components efficiently and stably.

It uses a computer to control a small grinding head to grind and polish the workpiece surface, and precisely controls the amount of material removal on the workpiece surface by controlling process parameters such as residence time of the grinding head on the surface of the workpiece, the speed of the grinding head, relative pressure, etc.

This technology has broad application prospects, particularly in the manufacture of off-axis aspherical mirrors. The efficiency and precision of processing off-axis aspherical surfaces can be further improved using CCOS technology.

The key points of CCOS technology include CCOS control model, aspherical surface shape quantitative measurement technology, CNC equipment and its numerical control technology, etc.

By introducing the concept of “virtual processing” for iterative evaluation of solutions and parameters, the CCOS method of aspherical surface processing can significantly improve the processing accuracy, reduce the theoretical processing margin, and thus optimize the performance of optical elements . Helpline: 13522079385

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: What is Strain Disc Polishing (SLP)

Great Light CNC Machining Services 28/12/2024 08:52

Stress Disk Polishing (SLP) is a computer-controlled polishing technology. It is based on the basic application of the mathematical mechanics of shell elastic deformation. Using a large size abrasive stress disc with controllable elastic deformation, active deformation technology is used. for polishing. This polishing method is mainly used in the fields of optical engineering and materials and devices, including optical design and processing, optical polishing, etc. The strain disk polisher is a scientific instrument specially used for this technology, which plays an important role in the engineering and technology fields related to information and systems science. This polishing technology has a place in the polishing of ultra-precision optical components due to its precision and controllability. It is closely related to small grinding head polishing (CCOS), liquid jet polishing (FJP), ion beam polishing (IBF) and air polishing. Bonnet polishing and magnetorheological polishing (MRF) together constitute the CNC polishing method currently widely used in the polishing of ultra-precision optical components‌

Stress disc polishing technology: make the surface quality more refined

1. Principle

Stress disk polishing technology is a surface treatment method that uses abrasives composed of chemical liquids and hard particles to treat the surface under the action of high-speed rotation of the stress disk. During the machining process, due to the high-speed rotation of the stress plate, friction will occur between the grinding material and the surface, causing defects and irregularities on the surface to be rejected or filled. At the same time, the presence of chemical liquid can also remove impurities such as oxides and metal ions on the surface, thereby making the surface smoother and finer.

2. Features

(1) Effectiveness

Strain disc polishing technology can effectively process the surface in a short time and process the surface of different materials. In addition to being used for metallic materials, this technology can also be used for processing non-metallic materials such as semiconductors, glass and quartz.

(2) High precision

Strain disc polishing technology can effectively improve surface roughness and finish, and can achieve large-area flatness at the submicron level.

(3) Environmental protection

Compared with traditional mechanical processing and electrochemical grinding technologies, strain disc polishing technology produces relatively less liquid waste, and the discharged waste liquid is more environmentally friendly after pretreatment, in line with national environmental protection requirements. the environment.

3. Request

Strain disc polishing technology is widely used in semiconductor, optics, precision instruments and other fields. In the semiconductor field, strain disk polishing technology can be used to effectively process the chip surface and improve the optical and electrical properties of the chip; in the field of optics, this technology is widely used in the polishing of optical components such as telescopes; lenses and laser lenses; In the field of precision instruments, this technology is often used for surface treatment of high-precision instruments.

4. Future development trends

With the continuous development of science and technology and continuous in-depth research on strain disc polishing technology, the application of this technology in the field of precision manufacturing will become more and more extensive. At the same time, researchers are constantly exploring new polishing fluid formulas and processing techniques to improve the processing efficiency and quality of this technology, reduce costs, and bring more convenience and contribution to industrial production.

【Conclusion】

Strain disk polishing technology is an efficient, high-precision and environmentally friendly surface treatment method with broad application prospects. Although there are still certain bottlenecks and challenges in this technology, I believe that with the continuous advancement of technology and continued exploration, the stress disc polishing technology will have space for development. wider.

Consult polishing equipment: 13522079385

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CNC Knowledge: What is hood polishing

Great Light CNC Machining Services 28/12/2024 07:51

‌Bonnet Polishing‌ is a method of modifying and polishing optical parts, which belongs to the field of mechanical engineering. It uses a spherical crown-shaped polishing head filled with air to form an airbag, and a special polishing film is pasted on it. Through the rotational movement of the airbag and the relative movement between the workpiece and the polishing film of the airbag, the abrasive particles in the polishing fluid remove the surface material of the workpiece in a precise manner and controllable, thereby realizing modification and polishing of complex materials. optical surfaces.

This technology was initially jointly developed by the optics laboratory of University College London and the British company Zeeko based on Computer Controlled Surface Shaping (CCOS) polishing technology. It solved key technical problems such as airbag development, polishing movement mode and equipment design. , and finally invented optical component airbag polishing technology‌.

Airbag polishing technology has a wide range of applications, especially in the processing of high-precision curved surface components, such as high-precision optical components. These components play a key role in the fields of aerospace and military defense, so it is crucial to develop it. its level of ultra-precise batch processing.

Due to the high cost of dedicated airbag polishing machines and the limited processing range of full-size airbag polishing machines, researchers developed a robotic airbag polishing system by combining airbag polishing technology airbags and robot-assisted treatment technology to reduce equipment costs and expand the scope of application.

In addition, the advantages of airbag polishing technology include uniform material removal, high polishing efficiency and good consistency. These advantages make it excellent in processing optical glass and other materials. For example, K9 optical glass was polished via an experimental annular airbag polishing platform. The study found that as the airbag pressure increases, the polishing efficiency of K9 optical glass increases, which shows that airbag polishing technology has a significant effect on improving quality of the surface. of materials.

Helpline: 13522079385

The polishing tool used is a special flexible airbag. The shape of the airbag is a spherical crown, and a special polishing mold, such as polyurethane polishing pad, polishing cloth, etc., is attached to the outside. It is installed on the rotating work parts to form a closed cavity. The cavity is filled with low pressure gas and the gas pressure can be controlled. The polishing head itself rotates to create a polishing motion. The part can rotate and perform CNC link motion in the X, Y, and Z directions. When the part is a rotating surface, the part rotates and perform CNC link motion in the X and 2 directions; when the part is a free-form surface, the part does not rotate but performs CNC linkage movement in the X and Z directions.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: Development and application of precision grinding, polishing and testing equipment for large diameter optical components

Great Light CNC Machining Services 28/12/2024 06:49

Summary: Ultra-precision processing of large diameter optical components is a complex and systematic project, involving professional knowledge in various fields of electromechanical control such as precision machine tools, numerical control, technology and technology processing, precision detection and compensation control. is closely related to the high end of a country. Manufacturing technologies and equipment development capabilities are closely related and also constitute a concentrated expression of a country’s overall national strength. This article mainly introduces the research progress made by the Micro-Nano Joint Processing and Inspection Laboratory of Xiamen University in the ultra-precision processing technology and equipment of large diameter optical components. . It focuses on the two processing processes of grinding and polishing optical components. large diameter optical components and their supporting precision detection technology, developed on the research and application of grinding equipment and unit technologies, controllable airbag polishing machine tools and processing technologies related units, precision testing equipment and related unit technologies, etc. These technical studies start from the needs of ultra-precision machining, rely on domestic and foreign experience and research results, and integrate equipment, technology, testing and other aspects to form grinding, polishing and testing equipment and process technology with independent intellectual property rights. Ultra-precise processing system for large diameter optical components. These technologies and equipment guarantee high-quality, ultra-precise processing of large diameter optical components.

Keywords: large diameter optical components; ultra-precision machining; grinding processing equipment; precision detection;

Dr. Guo Yinbiao, Distinguished Professor of Minjiang Scholar, his main research areas are ultra-precision optical processing, advanced equipment development and production.

Free-form optical surfaces such as aspherical surfaces have superior optical properties. Under the same functional requirements, instruments with better imaging quality, simpler structure, lower cost and lighter weight can be obtained, which is indispensable in the fields of aerospace, military and of defense. The key core components in shortage are widely used in advanced civil and defense technology fields such as large astronomical telescopes, laser nuclear fusion devices, infrared thermal imaging and medical imaging equipment. Driven and motivated by the national optical engineering mission and the increasing demand for optoelectronic consumer products, its processing technology must increasingly evolve in the direction of high efficiency, high precision and high quality. Ultra-precision machining technology for large diameter optical components depends not only on machine tools, cutting tools and processing methods, but also on measurement and control technology, including machines, light, electricity, sensing technology and computer technology. achievement in several disciplines. comprehensive application, but also plays a role in promoting the development and progress of many high-tech technologies. The processing of large diameter optical components is an important indicator of a country’s advanced manufacturing technology level, and the overall national strength has always imposed a technological embargo on China in this field. Therefore, conducting research on ultra-precision processing technology of optical components will help ensure the safety of my country’s important technologies. My country’s “Twelfth Five-Year Plan” development plan has formulated relevant instructions, namely the “National Medium and Long-Term Plan”. term Overview of the scientific and technological development plan” Concerning the spirit of “key technologies for the manufacturing of key basic parts and mass production as the first priority theme of the manufacturing industry”.

Ultra-precision machining of large diameter optical components generally requires processes such as coarse grinding, fine grinding, polishing and coating to improve the precision of the workpiece surface and reduce roughness and defects. underground. Among these processes, the fine grinding and polishing of large diameter optical components is particularly important, which to a large extent determines the processing quality level of large diameter optical components. Among them, precision grinding basically determines the surface precision of large diameter optical components. optical components. At the same time, in order to reduce the subsequent polishing workload, it is necessary to minimize the extent of damage on the surface of the optical element during the precision grinding process. Form too many defects and damage, and polishing is the necessary guarantee to achieve an ultra-smooth optical surface with low damage caused by defects. Therefore, from the perspective of ensuring the processing quality of large diameter optical components, precision grinding and high precision polishing. The methods complement each other and are essential. Few in number, and high precision machine tool equipment are the prerequisite to achieve precision grinding and polishing. Due to technical bottlenecks, it is difficult to develop high-precision machine tool equipment with the current hardware design and development, and the cost is too high, which inevitably leads to large processing errors when precision grinding and polishing of large diameter optical components. In order to obtain higher precision and better quality optical components, additional compensation processing should be carried out to improve the processing quality of optical components. However, current domestic optical measurement and inspection equipment has limited adaptability, generally has a small diameter and high cost. At the same time, as a necessary means to obtain information on the size and processing quality of optical components, the development of measuring equipment and evaluation technologies for large diameter optical components is equally important . It can be said that precision grinding and polishing equipment is the manufacturing method to obtain high-precision large-diameter optical components, while its precision testing equipment and evaluation technology are the guarantee the smooth running of the entire treatment process. All three are essential. , and they all form the basis of large diameter optical components. An essential link in the precision manufacturing of optical components. Therefore, to strengthen the research on precision manufacturing of large diameter optical components, a three-pronged approach should be adopted. Only by overcoming and mastering the technical bottlenecks of these three aspects can the precision manufacturing and processing of large diameter optical components be realized. truly achieved and assured.

Driven by large-scale optical engineering projects such as laser fusion and space telescopes, Western developed countries, such as the United States and Japan, have made significant progress in ultra-precision manufacturing technology large diameter optical components. In terms of equipment, Livermore National Laboratory in the United States has developed the LODTM single-point diamond cutting machine tool (135-2207-9385), capable of processing optical components of Φ1400mm, with surface precision up to PV≤0.025μm and surface roughness Ra≤5nm.

The OAGM2500 ultra-precision grinder (159-1097-4236) developed by the Cranfield Precision Engineering Research Institute in the United Kingdom can process Φ2000mm aspherical optical elements with PV surface accuracy≤1μm.

The AHN60-3D composite machine tool developed by Japan’s Toyota Machinery can grind non-axisymmetric optical elements with a PV of 0.35 μm and a surface roughness Ra of 0.016 μm. In terms of processing methods and processing technology, in order to obtain high-quality optical element surface morphology, Ohmori et al from the Institute of Physics and Chemistry of Japan proposed an electrolytic grinding method in ELID line (13501282025), which allows mirror processing. optical elements.

In terms of optical surface integrity control, technologies such as CNC polishing technology (CCOS), strain disc polishing technology, airbag polishing technology, magnetorheological polishing technology and Plasma method based on small tool processing can effectively remove the underground damage layer, and It can improve the surface quality and shape accuracy of the workpiece in a targeted manner. These advanced ultra-precision processing technologies have fundamentally solved the problem of processing large diameter optical components. However, overseas developed countries have imposed strict technology and equipment embargoes on our country, which has led to the backward development of ultra-precision processing technology for large diameters. diameter optical components in my country.

At the same time, the country is also fully aware of the importance of large-diameter optical components in civil, national and military fields, and has clarified the need to strengthen research on precision manufacturing of large-diameter optical components . projects, it has intensified relevant processing technology and research on equipment development and other aspects. In terms of equipment, AVIC Institute of Precision Machinery developed Nanosys-300 ultra-precision composite processing machine tool, and Harbin Institute of Technology developed composite processing machine tool large-scale curved ultra-precision systems, both of which can process aspherical optical surfaces. The optical CNC machining machine tool (AOCMT) developed by the National University of Defense Technology has a maximum processing capacity of 650mm for silicon carbide parts with a diameter of 116mm, the precision of milling and forming is 8.9 μm. the workpiece after polishing is (1/20 ~ 1/30) λ, surface roughness 2 ~ 5 nm. Xiamen University has developed a large-sized rectangular optical plane precision grinder.

In terms of processing technology, Xiamen University has developed computer-aided manufacturing process software for aspherical optical surfaces. In terms of optical integrity control, the National University of Defense Technology has carried out research on computer numerically controlled polishing technology (CCOS), the National University of Defense Technology and the Institute Chinese physics and other institutions have developed magnetorheological polishing. machine tools. Harbin Institute of Technology, Zhejiang Lui University of Technology and Xiamen University studied airbag polishing technology and produced prototypes for testing. In addition, Xiamen University has also conducted research on the environmental control of optical precision processing and plans to improve the processing precision of optical components by compensating material defects through non-material means.

At present, driven by the needs of major national optical engineering tasks such as advanced military and space optical systems, laser nuclear fusion and large astronomical telescope projects, optical component manufacturing and testing technology China’s large diameter industry has developed rapidly. In terms of equipment guarantee for its main processing routes, the prerequisite for achieving ultra-precision processing of large diameter optical components is to have high-precision grinding and polishing processing equipment, as well as of development technology of large size high precision grinders and grinders. polishing equipment has always been recognized Because it is a technology that requires sustainable development, a technology that cannot be disclosed and a technology that cannot be copied, high-quality grinding and polishing precision and related testing equipment remain the bottleneck limiting the development of ultra-precision machining technology in our country.

In addition, to achieve ultra-precision processing of large diameter optical components, in addition to high-precision grinding and polishing equipment, a series of key supporting unit technologies are also required. These supporting technologies include: ultra-precision grinding and polishing processing technology. and technology, precision machine tool integration technology, ultra-precision environmental monitoring technology, tool dressing and dynamic and static balancing technology, computer-aided manufacturing and inspection software, as well as as inspection path planning and corresponding compensation processing strategies.

Based on the development needs of large diameter optical components, the research team of Xiamen University Micro-Nano Joint Processing and Testing Laboratory has carried out in-depth research on grinding and grinding equipment. precision polishing, processing technology, computer-aided manufacturing software and long supporting precision equipment for large diameter optical components. Researched testing equipment and technology, etc., and achieved outstanding scientific research results. This article takes the key process of grinding and polishing large-diameter optical components as the main subject of discussion, and introduces the research status of the research group of Xiamen University in the development of optical equipment and technology. associated units to achieve high precision and high efficiency. and highly automated precision processing of large diameter optical components.

Machine tools and large diameter optical component precision grinding unit technology

Large aperture optical elements generally use fragile materials and have the characteristics of large aperture and complex surface shape, which brings greater difficulties and challenges for their precision processing. At present, precision machining steps and procedures for large diameter optical components made of hard and brittle materials generally include milling the blank to remove excess material, then rough grinding until to a certain surface precision, then fine grinding to obtain a semi-finished product. product that meets the designed surface precision. , and finally polishing to remove the surface/sub-surface damage layer to obtain an ultra-smooth optical surface. The whole treatment process is relatively complex and requires precise process control, detection and compensation treatment. Therefore, in order to meet the precision processing of large diameter optical components, machine tools with performance characteristics such as high rigidity, high precision and stability are indispensable, among which large diameter precision grinders diameter are the first to bear the weight.

At present, in terms of manufacturing precision grinders, industrially developed countries such as the United States, Japan, the United Kingdom and Germany enjoy a high reputation internationally. Representative products such as the OAGM2500 six-axis ultra-precision CNC grinder developed by the Institute. of Precision Engineering from Granfield University in the UK can be used for ultra-precision turning, grinding and coordinate measurement. The Japanese company Nagasei owns SGC/SGE/N; 2C/NIC/RG and other series of ultra-precision grinders can be used for aspherical surfaces (free-form surfaces) and ultra-precision flat mirror processing of different sizes in addition, Moore Company’s Nanotech, Freeform series from Precitech Company, German Satisloh; The company developed the GII, Profimat series of Boryeong Machine Tool Co., Ltd. The MT and MFP series from the Swiss Meggler Machine Tool Company also achieve high machining precision.

Nationally, it is slightly behind. The Micro-Nano Joint Processing and Inspection Laboratory of Xiamen University used foreign advanced manufacturing technology as a reference and based on China’s ultra-precision processing needs for optical components large diameter, it has developed a number of large diameter high precision horizontal axis rectangular table planes, this article will take the developed 2MK7160 surface grinding machine and its unit technology as an example.

1. Schematic design and prototype development of large diameter precision grinder

In order to ensure that the developed large-diameter surface grinding machine has the performance characteristics of simple structure, good overall rigidity and high grinding efficiency, the R&D team first conducted a comprehensive analysis to break down the entire machine tool development work into key components. , key technologies, auxiliary equipment and electrical and CNC systems. Conduct modular research on other parts. The complete machine tool is determined to be a moving column CNC horizontal axis rectangular table surface grinder structure, with a complete sheet metal protective cover on the periphery. The traditional guide rail structure of the surface grinder is modified, and the bed base adopts a T-shaped layout and a split casting shape to improve the rationality of the process. A combination of artificial aging and natural aging is used to ensure the long-term stability of large base parts. Numerical design and engineering analysis are used to fully demonstrate the design plan, and the design and structural static and dynamic analysis of the complete machine plan are carried out to ensure the performance of the prototype machine.

In order to improve the rigidity of the process system, a grinding wheel spindle supported by hydrodynamic and static pressure bearings is used to achieve high rotational precision and smooth movement. Each axis transmission system is driven by a servo motor to drive a high-precision ball. Hydrostatic guide rails are used in the XY direction and cross nanometers. The linear array with 100 level resolution forms a fully closed control loop. The guide rail adopts block structure, more reasonable in craftsmanship and rigid. enough to achieve high processing precision, thereby maintaining high linear motion precision and high rigidity. The CNC system uses the high-end FANUC 31i system, which is based on the Windows operating platform and is simple, flexible and easy to master. The auxiliary system of the crusher includes cooling system, filtering device, lubrication system, oil and water mist purification device, etc.

The main supporting technologies are all developed independently. The grinding wheel dressing adopts the green carbon cup-shaped grinding wheel dressing method and develops a special dresser. Part detection is achieved by high-precision contact/non-contact sensors driven by movement. the machine tool. Process control and process technology are integrated into the computer. In the development of auxiliary manufacturing software, the workflow design method is used to realize the automated processing of human activities and machine tools, and the view/document design mode is used to realize the separation of processing data and user interface. Software development modules based on industrial computers include workpiece detection, grinding wheel dressing, processing monitoring, dynamic balancing and other systems. The grinding wheel dressing adopts two-axis precision cutting dressing technology to ensure the shape accuracy of the diamond grinding wheel and the dressing of flat and arc grinding wheels. Real-time on-site dynamic balance detection can reduce errors introduced by the spindle system. thus improving the processing precision of the part.

Process monitoring eliminates the impact of machine tool vibration and minimizes surface/subsurface damage. High-pressure cooling water is used to remove heat and grinding chips during the grinding process to improve the performance of the machined surface, and an oil mist purifier is used to remove the fluid atomized grinding to purify the processing space of the machine tool. At the same time, the processing environment control technology is independent of the external environment other than high-precision equipment, technicians and technical levels, ensuring that high-precision processing is not limited by the environment and ultimately realizes precision temperature control systems, multi-level higher-level vibration elimination technology and ultra-precision purification related technology. The designed parameters of the grinding machine are: the processing range of the workbench is 800mm × 600mm, the resolution of each axis is 0.1μm, the spindle adopts dynamic and static pressure supporting technology, the maximum speed is 3000 rpm, the maximum X-axis moving speed is 20m/min, and the Y and Z axes move. The maximum speed is 5m/min, the CNC system adopts FANUC 31i series, and the grinding wheel dresser adopts GC cup shape grinding wheel dresser. Figure 1 shows the 2MK7160 large diameter horizontal axis rectangular table surface grinder designed and developed.

2. Hydrostatic support technology

Hydrostatic pressure has the characteristics of small difference between dynamic and static friction coefficients, smooth movement, high rigidity, vibration absorption, large load capacity and fast dynamic response. In order to ensure the rigidity and precision of the movement of the process system, the mill adopts a closed system. Hydrostatic pressure support technology and development of part-type static pressure guide rail structure. This structure is simple and has good rigidity, which greatly reduces the difficulty of processing, assembly and debugging of commonly used closed static pressure guide rails, and facilitates disassembly and debugging. more convenient assembly.

The developed piece-type guide rail technology was first applied to the horizontal X axis of the first developed MK7160 large diameter surface grinding machine, and after its success, it was first applied to the vertical Z axis of large diameter grinding machine 2MK7160. Research revealed that it was applied vertically. The Z-axis coin-shaped guide rail has good supporting performance and is better than the traditional contact guide rail structure. Figure 2 is the structure and application example of the developed block-type hydrostatic guide rail.

3. Grinding wheel dressing technology and device lighting

Mechanical components are generally hard and brittle materials that are difficult to process. The grinding wheel wears out easily and the processing capacity is lost. In order to ensure the surface sharpness and precision of the abrasive grains of the diamond grinding wheel, it is necessary to develop dressing technology suitable for arc diamond grinding wheels, to realize the dressing and sharpening of arc diamond grinding wheels to guarantee their processing capabilities. The research team proposed the dressing method of the cup-shaped arc shell of the arc diamond grinding wheel, as shown in Figure 3, which can shape and sharpen the arc diamond grinding wheel through to the envelope movement of the cup-shaped grinding wheel. In terms of technological implementation, the machine tool provides the lateral reciprocating movement required for the dressing movement and the rotational movement of the diamond grinding wheel spindle, and the dressing device ensures the swinging, dressing feed and the rotational movement of the cup-shaped grinding wheel.

During the dressing process, the abrasive grains falling from the cup-shaped grinding wheel will impact and grind the abrasive grains and bonding agent of the diamond wheel, thus completing the dressing of the arc diamond wheel. In terms of processes and auxiliary systems, develop computer-aided processing software for dressing the cup-shaped grinding wheel shroud which integrates key unit technologies such as surface shape accuracy measurement of grinding wheel, error modeling, radius compensation, dressing process, etc., and can realize arc diamond grinding wheel dressing devices Multi-axis linkage control with machine tools.

The development of the cup-shaped grinding wheel shroud correction method and device for arc-shaped diamond grinding wheels has greatly ensured the processing performance of arc-shaped diamond grinding wheels and improved its processing efficiency. The biggest feature of this dressing technology is that its dressing objects are not limited to metal-bonded arc diamond grinding wheels, but also suitable for dressing resin-bonded grinding wheels and ceramic-bonded grinding wheels.

4. Computer-Aided Manufacturing (CAM) Software

Large diameter aspherical surfaces are typical parts with complex surface shapes that are difficult to process. Each axis of movement of the grinder must coordinate the movement to complete the process. In addition, the characteristics of machine tool mechanical systems have certain limitations. When their performance cannot be improved further, process optimization is necessary. In order to ensure the processing precision of grinding and ensure the full utilization of the precision characteristics of CNC grinding machines, it is necessary to select reasonable and efficient processing techniques and processing planning according to different types of workpieces and specific structures of the grinding machine, and optimize grinding processing parameters to improve the accuracy of surface shape and reduce underground damage caused by grinding. Among them, the control method of processing compensation is the key.

To this end, the research team proposed a series of interpolation schemes and control strategies of aspherical surface profiles, optimized them, and established modeling compensation technology based on the sensing and evaluation of errors at the same time, in order to delay profile wear; grinding wheel and ensure the processing of grinding wheel capacity, in-depth analysis of the wear mechanism of arc grinding wheels, needle grinding wheel uniform wear and speed control technology is proposed to effectively improve the service life of the millstone; for the arc radius error in aspherical surface processing, it is proposed to separate and detect the error components and carry out compensation processing to improve the processing accuracy; In order to improve the efficiency of dressing wheels, a technology for optimizing the dressing parameters of grinding wheels is proposed.

Based on the process optimization plan mentioned above, the processing technology is reasonably formulated and combined with computer technology, especially the use of computer-aided manufacturing and measurement, to realize processing and automatic control of processing process information, improve processing process automation and processing efficiency; and research on CNC servo systems and micro-displacement control, analysis of different workpiece processing methods, path planning and programming optimization, to ensure the correct use of machine tools during processing, set of CNC processing characteristics and processing precision of the workpiece.

As shown in Figure 4, the computer-aided manufacturing (CAM) system software developed by the research group is used to achieve ultra-precision grinding. Its functional modules include grinding processing, surface measurement, grinding compensation, surface adjustment and environmental monitoring, etc. ., the application of auxiliary manufacturing system software can make the whole grinding process more efficient and convenient. CAM software development can automate CNC programming for precision grinding of large diameter aspherical optical surfaces and integrates key technologies in the grinding process, including process analysis and design, parameter input, processing mathematics of machining trajectories, programming, measurement of the part and grinding wheels. Functional modules such as dressing, processing monitoring and communication with the machine tool. The relationships and functions of each functional module are illustrated in Figure 5.

Machine tool and optical component controllable airbag polishing unit technology

During the shrinkage process, hard and brittle materials are prone to brittle fracture, making the machined surface rough. Conventionally, large diameter optical elements often require polishing and other finishing processes after precision and ultra-precision grinding and forming. The aim is to remove the surface deterioration layer and damage formed in the previous process and make the part surface ultra-precise. -smooth. However, polishing treatment can easily destroy the surface precision of the workpiece, so subsequent corrective polishing treatment is often necessary to obtain large diameter optical components with high surface precision. Traditional methods for correcting the surface shape of optical elements are difficult to adapt to the development needs of modern optical systems due to defects such as long processing cycles and slow convergence of surface shape. Therefore, many advanced modern polishing methods have emerged, such as small grinding head CNC polishing. and strain disk polishing, ion beam polishing, magnetorheological polishing, and controlled airbag polishing and other deterministic polishing technologies.

Among the many emerging deterministic polishing technologies, small grinding head CNC polishing is the most widely used. This technology has the advantage of being able to polish and correct complex free-form part surface shapes. In order to reduce the impact of interference between the polishing disk and the workpiece surface on the precision of the workpiece, the size of the small grinding head CNC polishing tool is generally small, which facilitates the formation of mid- and high-frequency errors on the component surface when using regular processing paths.

The strain disk polishing technology proposed by the University of Arizona in the United States can solve this problem, but its modification ability is poor and the control is complicated. In addition, small grinding head and stress disk are both contact processing methods. the contact between the disc surface and the component during processing is easy. This results in elastic deformation of the component, making it difficult to process the shape of the component surface with a high degree of precision. Although ion beam polishing technology can achieve local correction polishing, its polishing efficiency is extremely low and requires extremely high processing environment and high costs. In contrast, magnetorheological polishing and airbag controlled polishing technologies are flexible polishing technologies that can achieve high processing precision. However, magnetorheological polishing is very expensive, making it difficult to apply on concave curved surfaces and large diameter and steep surfaces. Based on the above analysis, the research team purposefully developed the controllable airbag polishing technology and its machine tools.

1. Development of flexible and controllable airbag polishing machine tools

The flexible airbag polishing technology was first proposed by Professor Walker of the London Optical Laboratory, UK, and was later developed into a series of products by the UK company ZEEKO (135-0128-2025) . Based on the digestion and absorption of its products, the research team developed the first machine tool and controllable flexible airbag polishing unit technology in China. As shown in Figure 6, the airbag polishing machine tool adopts a gantry structure as a whole, consisting of a workbench base, a column and a beam, a central sliding plate and of a pin box structure.

twoThe shaft airbag polishing tool is the core component of the entire airbag polishing machine tool. In structural design, it is not only necessary to ensure the accuracy of movement of the entire mechanism, but also to reserve sufficient space for additional functions. Airbag polishing adopts a precession processing method, that is, during the polishing process, the main axis of the airbag always forms a fixed precession angle with the local normal line of the workpiece. In order to facilitate the control of the spatial posture of the airbag rotation axis, the dual-axis airbag polishing tool uses two rotation axes Z1 and Z3 to control the spatial posture changes of the airbag. main axis of the Z2 airbag at the same time. The Z1, Z3 and Z2 axes of the two-axis airbag polishing tool intersect at the center of the airbag ball joint. Through the theoretical analysis of motion space, it is calculated that when the Z1 axis and the Z3 axis are 45° in space, that is, the spatial angle of the The entire mechanism is 45°, the spatial movement range and rigidity of the entire airbag Polishing tools are the most suitable.

2. Flexible and controllable airbag design and cutting technology

In order to prevent the rigid polishing head from damaging the free-form surface, the airbag polishing machine tool uses a spherical crown-shaped airbag with a certain inflation pressure as the polishing tool. This not only ensures good consistency between the polishing head. and the surface of the workpiece to be polished, but also adjusts the internal pressure of the airbag. Controls the polishing efficiency and surface quality of polished parts. For this reason, the flexible airbag polishing method is a polishing method with great development potential, especially suitable for polishing aspherical and free-form surfaces.

Flexible airbag polishing uses a unique precession movement method, that is, during the polishing process, the rotation axis of the airbag is always polished at a fixed angle (called precession angle) relative to the local normal line of the part via specific processing paths and path control. , chaotic processing traces are formed in the contact area, and a suppression function close to the Gaussian distribution is generated. This processing method helps to reduce the formation of intermediate frequency errors on the polished surface. It is precisely on this characteristic that the polishing of airbags is based. The processing technology is widely used in component intermediate frequency error correction processing.

To ensure that airbag processing can be applied to different processing objects, the research team studied airbag polishing heads with different structural shapes to obtain polishing heads with different deformation modes and rigidities, including including pure rubber airbag heads, integrated steel mesh rubber airbags. integrated heads and thin There are various shapes such as steel plate airbag heads, and the deformation characteristics and removal functions of various airbag heads have been studied in a targeted manner. Figure 7 shows the flexible airbag polishing head with an integrated steel mesh developed inside.

In order to further improve the processing efficiency and reduce the tedious process of cutting the airbag polishing head, the research team separated the cutting process of the airbag head, designed and added an offline airbag cutting device and developed an offline airbag cutting device as shown. in Figure 8. The device consists of a base. It is composed of swing motor, swing base, swing guide rail, feed motor, guide rail, grinding wheel base, grinding motor grinding wheel spindle, a dressing wheel, a polishing head motor, a protection device. and other parts.

The swivel motor is attached to the bottom of the base and is connected to the swivel base via a reducer. The guide rail is fixed on the swivel base. The feed motor and feed spindle drive the grinding wheel base through the guide rail to finish. the feeding movement. The grinding wheel spindle motor drives the dressing wheel through the coupling, turn to complete the movement of the dressing wheel.

The base of the polishing head part is fixed at one end of the base by means of screws, and the polishing head of the airbag is rotated by a pulley and a polishing head motor. In the process of offline dressing of the airbag head, the dressing of the airbag head is completed by the rotation of the rubber airbag head, the rotation of the grinding wheel spindle, the movement feed axis and the oscillation movement of the oscillation axis. . At the same time, a dynamic balancing device of the airbag head is installed on the top of the protective cover to detect the vibration and rotation speed of the airbag head during rotation to facilitate the Airbag head balance adjustment and improve cutting precision.

3. Airbag polishing and motion control simulation software

In order to ensure that the airbag polishing process can perform the expected functions, the research team fully studied the processing mechanism of airbag controllable polishing, combined experiments and simulations, and determined the impact of different airbag polishing conditions. process on the polishing contact area, as well as the static and static conditions of airbag polishing under different conditions. Dynamic shrinkage function and polishing dwell time algorithm based on shrinkage function are studied. Based on the study of the precession control method in the airbag polishing process based on kinematic theory, the most effective precession control algorithm was obtained.

The research has carried out in-depth research on airbag processing in continuous precession polishing mode. Particularly, on the basis of pressure control and posture control, the optimal efficiency algorithm, controllable stiffness algorithm and four-axis linkage, as shown in Figure 9, were. studied respectively. The control algorithms, etc., and on this basis, the simulation and motion control software for the controllable polishing of flexible airbags has been compiled. Figure 10 shows the developed software interface. This motion simulation and control software greatly facilitates the planning and control of airbag polishing movements, and effectively promotes a high degree of automation in the airbag polishing process.

Precision testing devices and unit technology for large diameter optical components

The processing of large diameter optical components generally goes through three stages: milling, grinding and polishing. In order to ensure the processing margin and precision of each process, each processing step must match the corresponding precision measurement and detection technology. In the processing of large diameter optical components, the grinding step is mainly intendedIn order to achieve shape accuracy closer to the design requirements, the surface accuracy obtained at this stage will largely determine the workload of subsequent surface convergence processing, so the detection of its surface accuracy is crucial.

Generally speaking, the accuracy requirements of the surface error detection device in the process of grinding large-diameter aspherical optical surfaces range from tens of microns to sub-microns. Based on this, the research team developed technology for targeted surface shape error detection of large-diameter optical components.

Figure 11 shows the in situ detection system developed by the research group. This detection system places the laser displacement sensor on the grinding spindle and uses the movement of each axis of the grinder to complete the detection of the surface shape of large diameter aspherical components. which can realize large diameter optical measurements of components. This detection method is in situ, and its characteristic is that it can avoid clamping, positioning and other errors caused by offline measurement of the workpiece, realize the surface precision measurement of workpiece processing, and provide processing error data for compensation processing. . Figure 12 shows the surface precision diagram after initial processing and compensation processing of large diameter aspherical optical elements using an in situ inspection system. After three compensation treatments, the PV value of shape accuracy decreased from 7.77 µm to 4.67 µm.

In addition, the research team also developed three-dimensional profile measurement offline precision inspection platforms for medium and large diameter (200 mm × 200 mm) and large diameter (400 mm) optical components. × 400 mm). Figure 13 shows one of the large-diameter offline precision sensing platforms. The platform adopts a fixed bridge structure. The travel of the XYZ axis is 400mm × 400mm × 150mm respectively. The positioning accuracy of each axis is ± 1 μm. is ± 3 μm. The detection platform adopts a multi-CPU structure composed of upper and lower computers. The upper computer implements functions such as system management, data processing and human-machine interface.

The lower computer is composed of two modules: motion control and data acquisition, which realizes functions of motion control and data sampling, analysis and real-time processing. The platform adopts contactless and contactless dual detection systems, which can be implemented according to different needs of parts.Real-time collection of part surface shape data is now available. The collected original surface shape data can be adapted to the actual surface shape of the processed part through relevant data fitting algorithms and error analysis, and the surface shape of the part adjusted is compared to the ideal shape. -ideal shape. Compare spherical surface shapes to obtain parameters such as aspherical surface shape errors and various aberrations, and provide processing compensation data for further processing.

In order to make the detection platform more practical for the detection of large-diameter aspherical components, the research team also developed aspherical surface measurement system software suitable for the detection of large-diameter aspherical components. The software includes the configuration module illustrated below. Figure 14, The measurement module, data analysis module and evaluation module have functions such as finding aspherical vertices, positioning error compensation, straightness, verticality and tilt error compensation. flatness and compensation for stem deformation errors. The software has two operating modes: manual and automatic. .

Figure 15 shows the surface shape and fitting deviation of aspherical optical elements measured using the developed large aperture optical inspection platform and software. The development of this detection device and related software has successfully provided strong precision measurement and compensation processing guarantees for the precision processing of large diameter optical components.

in conclusion

Precision manufacturing and processing of large diameter optical components constitutes comprehensive and complex system engineering. Its precision processing involves the removal mechanism and control of difficult-to-machine materials, the development of precision and ultra-precision machine tools, CNC technology, precision detection. , processing tools and cutting, materials and processing Condition and environmental control, error evaluation and compensation, processing technology and technology, etc., each of which is an important research direction, and there is a long way to go for deeper and systematic research. With the funding of relevant major optical engineering projects, the Micro-Nano Joint Processing and Inspection Laboratory of Xiamen University has carried out more explorations in precision component manufacturing and inspection equipment large diameter optics and achieved practical scientific research results, mainly reflected in the following: :

(1) A large-diameter four-axis precision grinder with a “T” layout has been developed. The machine tool adopts hydrostatic support guide rails, dynamic and static pressure spindles and dynamic balancing technology, and is equipped with a cup-shaped grinder. wheel dresser for dressing diamond arc grinding wheels. To meet the precision machining requirements of large-diameter aspherical optical components, a computer-aided manufacturing (CAM) system was developed that works with the grinder and contains several key unit functional modules.

(2) A large-diameter flexible airbag polishing machine tool was developed. The polishing machine tool adopts AB pendulum five-axis structure and “T” type gantry layout. The polishing head adopts a flexible airbag structure and has two processing modes. pressure and attitude control. Research and design of a variety of polishing processing paths and residence time algorithms, and development of computer-aided polishing (CAM) system for precision polishing machine tools.

(3) A medium and large diameter aspherical optical sensing platform was developed. The measurement platform has contact and non-contact measurement tools and methods, and measurement and evaluation software for large diameter aspherical surfaces has been developed. The software has automatic measurement and data capabilities. Functions such as analysis, evaluation and compensation can enable high-precision measurement and evaluation of large diameter aspherical surfaces.

A comprehensive analysis of the current state of technological development shows that although China has been able to process high-precision large-diameter optical elements, there is still room for improvement compared with foreign advanced levels. In the future, relevant innovative works. departments, research institutes and universities will be needed to explore and study new relevant processing technologies and methods, new processes and new detection technologies, with a view to achieving high-precision and high-quality processing of large diameter optical components on this basis. , ensuring the construction and development of my country’s relevant large-scale engineering projects and the implementation of the fields of national defense and military. Research work in the related fields of high-end equipment and numerical control will also help our country overcome foreign technological blockages, greatly improve our country’s precision manufacturing technology and equipment levels, and ensure the technological security of our country.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: Reasons for “dimensional instability” of CNC machine tools

Great Light CNC Machining Services 28/12/2024 05:48

1. The connection between the servo motor shaft and the screw is loose, causing the screw pre-motor to be out of synchronization and causing dimensional errors. When inspecting, you only need to mark the coupling between the servo motor and the screw. If you use faster magnification to move the workbench (or tool rest) back and forth, the two ends of the coupling will move significantly relative to each other due to inertia of the workbench (or turret). This type of defect usually manifests itself as a change in processing dimensions in only one direction, which can be eliminated by simply tightening the coupling screws evenly.

2. Poor lubrication between the ball screw and nut increases resistance to movement of the workbench (or tool holder) and prevents complete and accurate execution of movement instructions. This type of failure usually manifests itself as irregular changes in part size on a few wires. The failure can be eliminated by simply improving lubrication.

3. The resistance to movement of the machine tool table (or tool holder) is too great, which is generally caused by too tight adjustment of the inserts and poor lubrication of the surface of the guide rails of the machine tool. This defect phenomenon generally manifests itself as irregular changes in part size within a few wires. Simply readjust the insert and improve the lubrication of the guide rail.

4. The bearing is worn or improperly adjusted, causing excessive resistance to movement. This defect phenomenon also generally manifests itself by irregular changes in size on a few wires. Simply replace the worn bearings and adjust them carefully, and the fault can be eliminated.

5. If the screw clearance or clearance compensation amount is inappropriate, the fault can be eliminated by adjusting the clearance or changing the clearance compensation value.

Determination and repair of defects caused by unstable processing dimensions

1. The part size is accurate and the surface finish is poor

Reasons for failure: the tip of the tool is damaged and not sharp; the machine tool resonates and is unstable; processing technology is poor;

Solution: If the tool is worn or damaged and is not sharp, resharpen it or choose a better tool and recalibrate it; the machine tool resonates or is not placed smoothly, adjust the level, lay the foundation and fix it smoothly; the reason the machine crawls is drag. The guide rails of the board are very worn and the threads. If the lever ball is worn or loose, the machine tool needs to pay attention to maintenance. The iron wire should be cleaned after work, and lubricating oil should be added in time to reduce friction, choose a coolant suitable for processing the workpiece and try; choose a cooling fluid if it can meet the processing requirements of other processes. High spindle speed.

2. The workpiece produces a phenomenon of taper and large head.

Failure reason: The machine tool level is not properly adjusted, one is higher and the other is lower, resulting in unstable placement when rotating the long axis, the filler material is relatively hard and the tool is cut deeply, causing the tool to abandon; the tailstock thimble is not concentric with the spindle.

Solution: Use a spirit level to adjust the level of the machine tool, lay a solid foundation and fix the machine tool to improve its toughness; choose a reasonable process and appropriate cutting feed to prevent the tool from being stressed and adjust the tailstock;

3. The driver’s phase light is normal, but the size of the processed part is sometimes large and sometimes small.

Reasons for failure: the machine tool carriage operated at high speed for a long time, resulting in wear of the screw and bearings; repeated positioning accuracy of the tool holder deviated during long-term use, the carriage can return accurately; at the starting point of processing each time, but the size of the processed part always changes. This phenomenon is usually caused by the spindle. High speed rotation of the spindle causes significant wear on the bearings, leading to changes in machining dimensions.

Solution: Use a dial indicator against the bottom of the tool holder and change a canned cycle program through the system to check the repetitive positioning accuracy of the carriage, adjust the screw shank gap and replace the bearings. Use a dial indicator to check; the repetitive positioning precision of the tool holder. Adjust the machine or replace the tool holder; use a dial indicator to check whether it accurately returns to the program starting point after processing the part. If possible, inspect the spindle and replace the bearing. .

4. The part size differs by a few millimeters from the actual size, or there is a significant change in a certain axial direction.

Cause of failure: the rapid positioning speed is too fast and the drive and motor cannot respond; after long-term friction loss, the screw and bearing of the mechanical carriage are too tight, and the tool holder is too loose after the tool; replacement and cannot be locked tightly; editing program error, head and tail do not respond or tool compensation completes without cancellation; the electronic transmission ratio or pitch angle of the system is incorrectly adjusted;

Solution: If the rapid positioning speed is too fast, adjust the GO speed, cutting acceleration and deceleration and time appropriately so that the driver and motor can operate normally at the rated operating frequency after wear of the machine tool, carriage and screw; crane bearings are too tight. If it is stuck, it must be readjusted and repaired; if the tool holder is too loose after changing the tool, check whether the tool holder reversal time is met, check whether the turbine worm inside the tool holder is worn, and Is the clearance too big, is the installation too loose, etc.? ; if it is due to program reasons, you should modify the program, improve it according to the requirements of the part drawing, choose reasonable processing technology, and write the correct program. according to the instructions in the instruction manual; if it turns out that the size deviation is too large. Then check whether the system parameters are set appropriately, especially if parameters such as electronic gear and pitch angle are damaged. This phenomenon can be measured using. a dial indicator.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: Gyroscope hemispherical resonator processing solution

Great Light CNC Machining Services 28/12/2024 04:46

‌ Gyroscope resonator‌is an important part of the gyroscope, especially inHemispherical resonant gyroscopehe plays a central role. Gyroscope resonators are generally made of materials with stable physical and chemical properties, such as fused quartz, to ensure a high quality factor. To protect the resonator, it must be sealed in a high vacuum environment.

In a hemispherical resonant gyroscope, the resonator is connected to the support rod by welding, and the welding stiffness directly affects the impact of the input acceleration in the non-sensitive direction.

Therefore, even if there are relatively mature theoretical research on gyroscopes, if the material performance cannot meet the theoretical requirements or the welding process level is insufficient, the gyroscope resonator cannot be manufactured with success.

This shows that the manufacturing of gyroscopic resonators not only requires high-precision material processing, but also requires exquisite welding technology to ensure its performance and stability.

Let’s present it belowhemispherical oscillatorTreatment Solution: (Consultation Phone Number: 13501282025)‌

1. The hemispherical resonator production line with UPG-650 ultra-precision grinder and PF6-250 plasma machine tool as the core can achieve rapid production of resonators with frequency difference <1 MHz within a few hours.

2. Ultra-precise grinding

UPG-650 ultra-precision grinder, rotation precision <10nm, plastic domain grinding can reduce underground damage and improve the Q value of the vibrator.

3. Geometric error measurement

Self-developed aspherical surface measuring machine with dual contact and non-contact probes. The outer spherical roundness error, inner spherical roundness error and coaxiality error can be measured and obtained.

4. Plasma modification

PF6-250 plasma shaping machine tool can change the outer spherical roundness, inner spherical roundness, inner and outer spherical shell coaxiality and center column coaxiality. Resonator roundness change <100nm can be achieved within 15 minutes, and the roundness accuracy can be more than doubled.

5. Measurement of laser vibrations

Self-developed HRM-2 integrated laser vibration measuring system can measure and obtain frequency difference, Q value and T value of hemispherical vibrator, obtain stiffness axis angle, determine leveling position of the mass and eliminate the mass.

6. Plasma quality leveling

PF6-250 atmospheric pressure plasma treatment equipment can measure vibration after treatment. It performs several iterative processes in collaboration with the HRM-2 vibration measurement system, achieving quality leveling with a frequency difference <1 MHz in a total time of 10 minutes.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: Process know-how for processing titanium alloys

Great Light CNC Machining Services 28/12/2024 03:46

When the hardness of titanium alloy is higher than HB350, it is particularly difficult to process. When the hardness is lower than HB300, it is easy to stick to the tool and difficult to cut. Therefore, titanium processing problems can be solved from the blade. The blade groove wear that occurs when machining titanium alloys is the local wear of the back and front in the direction of the cutting depth. It is often caused by the hardened layer left over from previous treatment. Chemical reaction and diffusion between tool and workpiece material at processing temperature above 800°C is also one of the causes of groove wear. Because during the machining process, the titanium molecules in the workpiece accumulate in front of the blade and are “welded” to the blade under high pressure and high temperature, forming an accumulated edge. When the built-up edge separates from the cutting edge, it takes the carbide coating on the insert with it. Machining titanium therefore requires special materials and insert geometries.

(1) Use inserts with positive angle geometry to reduce cutting force, cutting heat and workpiece deformation.

(2) Maintain a constant feed to avoid hardening of the part. The tool must always be in a leading state during the cutting process. The radial cutting amount ae should be 30% of the radius during milling.

(3) Use high pressure and high flow cutting fluid to ensure the thermal stability of the machining process and avoid workpiece surface degeneration and tool damage caused by excessive temperature.

(4) Keep the edge of the blade sharp. Dull tools cause heat buildup and wear, which can easily lead to tool failure.

(5) Process titanium alloys to the softest state possible, because the material becomes more difficult to process after quenching, and heat treatment increases the strength of the material and increases blade wear.

(6) Use a large tool tip arc radius or chamfer to insert as much of the tool edge into the cut as possible. This reduces cutting force and heat at all points and prevents local breakage. When milling titanium alloy, among the cutting parameters, cutting speed has the greatest impact on tool life vc, followed by radial tool engagement (milling depth ) ae.

It is worth mentioning that because titanium alloys generate a large amount of heat during machining, a large amount of high-pressure cutting fluid should be sprayed onto the cutting edge quickly and accurately in order to quickly discharge the heat. heat. Nowadays, there are also unique structures of milling cutters specifically used for processing titanium alloys on the market, which can be better suited to processing titanium alloys.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: Technology for manufacturing and detecting holes in the air film in aircraft turbine blades

Great Light CNC Machining Services 28/12/2024 02:45

Film cooling technology is a key core technology that supports the improvement of the temperature resistance capability of hot aircraft engine components. It allows the flow of cooling air to be ejected through cooling structures such as film holes to form a film of cooling air covering the surface thereof. hot components to protect them from high temperatures. Taking turbine blades as an example, the principle of film cooling is shown in Figure 1. The processing precision and hole quality of the air film determine the reliability of turbine blades, which in turn affects the safety of the entire aircraft engine. Therefore, extremely strict acceptance requirements are imposed on air film holes, and their manufacturing technology is also questioned. In terms of machining accuracy, the main evaluation factors include hole diameter, hole position, roundness, cylindricity, axis vector angle, roughness and wall integrity of the hole, etc., which determine the cooling air flow, outlet position and angle, jet speed, etc. ., and thus affects the effectiveness of the cooling air film coverage. In terms of processing quality, we mainly focus on the shape and depth of defects in the hole wall/orifice formed by different hole making processes. Excessive defects can cause the blade to break when subjected to complex alternating loads. According to incomplete statistics, more than half of engine failures are related to damage and breakage of engine blades.

Figure 1 Block diagram of the film cooling principle of turbine blades

Figure 1. Schematic illustration of film cooling technology of a turbine blade

The base material of turbine blades is generally made of high temperature alloy materials that are difficult to process. The diameter of air film holes is generally 0.3-0.6mm, especially for large angle oblique holes, depth to diameter ratio. can reach 13:1. Therefore, special processing methods are generally used to process air film holes, including electric discharge machining (EDM), electrochemical machining (ECM) and laser processing.[3-4]. With the diversified development of blade structures and drilling needs, different drilling processes have also developed rapidly, showing a situation in which a hundred schools of thought compete. However, the development of air film hole detection technology is slightly slow.[5]. The reason is on the one hand related to the difficulty of collecting data on the geometric size and metallurgical quality of small holes, and on the other hand it is also related to the large number of air film holes in a single blade and difficulty in matching the production rate of hole making. In fact, it is not realistic to detect all characteristic elements from all holes in the air film. The high-pressure turbine blades of high-performance aero engines alone contain tens of thousands of air film holes. It therefore depends on the precision and quality of the holes made. depends more on the maturity of the manufacturing process and stability. In addition, as the performance requirements of aero engines increase, the gas turbine inlet temperature continues to increase, placing higher requirements on air coverage efficiency. cooling. Hole design has also evolved from early simple straight round holes to complex special-shaped holes, such as dustpan holes, cone holes, teardrop holes, cat ears holes , etc.[6-7]which poses a double challenge in terms of method of hole making process and assessment of manufacturing conformity.

In recent years, the field of aviation has developed vigorously, and the technology of manufacturing and detecting holes in air film has also triggered a research boom. This article reviews the advanced progress and application of typical hole making processes, and conducts trend analysis and summary. on the development of design requirements, further emphasizing that the manufacturing and air film hole detection technology The development direction of film cooling related technologies.

1. Air film hole manufacturing process

1.1 Making EDM holes

EDM hole making is currently the most mature and widely used process method in the field of turbine blade hole making. It has high processing efficiency and good stability. Based on the pulsed spark discharge between the tool and the workpiece (positive and negative electrodes), the material to be processed is engraved to achieve the processing effect of size, shape and surface quality specific to the part.[8]. The current and pulse width in the EDM holemaking parameters determine the size of the single pulse energy, which has a significant impact on the processing quality. The pulse stop (i.e. pulse interval time), internal flush fluid pressure, and discharge product output (i.e. residual ). The transportation process is closely related, so it also has a great impact on the quality of the hole wall and the processing efficiency. In fact, EDM machining technology can show its talents in the field of hole making, through the mature application of hollow tubular electrodes, which solves the problem of slag removal in the processing of small holes with large aspect ratios.

Figure 2 is a schematic diagram of the high-speed EDM small hole machining process. The discharge at the electrode tip continuously erodes the metal matrix material at the bottom of the hole. The hollow tubular electrode allows high pressure internal flushing fluid to circulate. and transport the residue generated by the landfill to prevent it from settling in the hole. Accumulation occurs at the bottom of the hole, thereby advancing the pulse discharge process steadily and continuously downward. Since EDM machining mainly removes material by hot melting, thermally induced defects, such as remelt layers, inevitably form on the hole walls. Some researchers previously believed that thermal defects could cause cracks to appear in the blade hole walls after long-term service, which could further expand under alternating loads, causing the blade to break .[9]. However, although the recast layer on the hole wall formed by different EDM holemaking equipment and processes can only be distinguished by the thickness of the recast layer on the mesoscopic scale, the microstructural morphology can vary significantly.

Dong Tao et al.[10]It has been reported that the recast layer formed by EDM of high-temperature alloys contains a large number of micropores, cracks and other defects, as well as cellular dendrite interfaces formed between different melt pools. However, this research group developed low temperature and high pressure internal fluid and narrow pulse width high frequency power supply, and, on the basis of high temperature single crystal alloy epitaxial growth technology, formed a recast layer of single crystal pore wall. , which is supersaturated and fully consistent with the orientation of the solid solution matrix with FCC network structure (Figure 3, Figure 4). Heat treatment is further used to control the precipitation of the γ’ phase inside the single-crystal recast layer, forming a pore wall fully consistent with the structure of the single-crystal matrix and completely eliminating the recast layer.[11]. However, it is undeniable that the microscopic holes and rough surfaces of the hole walls inside the recast layer cannot be removed by heat treatment and structural control. Compared to the existence of these geometric defects in the recast layer, these factors are more likely to be related to. failure. It is necessary to attract deeper attention.

Figure 2 Schematic diagram of the high-speed EDM small-hole machining process based on hollow tubular electrodes[2]

Figure 2. Schematic illustration of EDM drilling via tubular electrode[2]

Figure 3 Diffraction points of a single crystal superalloy epitaxial growth matrix and a recast layer

Figure 3. Diffraction pattern of single-crystal superalloy matrix and adjacent single-crystal recast layer formed by epitaxial growth

Figure 4 Microscopic morphology of the recast layer of the hole wall controlled by heat treatment

Figure 4. Microstructure of the hole wall of the recast layer formed by heat treatment

1.2 Production of electrochemical holes

At present, the electrochemical machining processes that can be relatively maturely applied to blade hole manufacturing include electrohydraulic beam (Fig. 5) and electrolysis EDM (Fig. 6) composite processing. Electrohydraulic beam treatment involves inserting an electrode wire into a hollow glass tube. The acidic electrolyte flows from the tip of the glass tube under pressure to form circulation, and then removes the treated material according to the principle of electrochemical corrosion. The advantage of electrochemical treatment lies in controlling thermally induced defects, but in acidic electrolytes, the γ phase of single crystal superalloys will be preferentially corroded compared to the γ’ phase, causing the hole wall to inevitably form a layer electrochemical corrosion. EDM-electrolysis hybrid machining replaces the high-pressure internal flushing fluid of the EDM hole machine from deionized water with saline solution, and then removes the recast layer from the hole wall by the electrolysis reaction on the side wall while discharging onto the EDM. advice.

Since the entrance section of the hole undergoes electrolytic corrosion for a longer period of time than the exit section, the removal effect of the recast layer in the entrance section is generally better, while the recast layer which has not been completely eliminated remains in the output section. Another advantage of electrochemical treatment is the blunting effect on the sharp corners of the orifice. If the intersecting lines formed by the air film hole wall and the inner and outer surfaces of the blade are not chamfered, they may be damaged after long-term service. Stresses are concentrated at the sharp corners of the hole and cracks appear particularly severe for the sharp edges of large inclined holes. However, it is undeniable that the rupture of the glass tube processed by the electro-hydraulic beam can make the air film hole too large; EDM-electrolysis composite processing cannot yet be applied to industrial production in terms of quality and technological control. maturity At the same time, the treatment of electrochemical waste is also an issue that needs to be considered comprehensively.

Figure 5 Schematic diagram of the production of electrohydraulic beam holes[12]

Figure 5. Schematic illustration of electro-flux machining[12]

Figure 6 Schematic diagram of composite EDM-electrolysis machining[13]

Figure 6. Schematic illustration of hybrid EDM and ECM process[13]

From the perspective of manufacturing capabilities, the glass tube electrodes involved in electrohydraulic beam hole manufacturing and the hollow tube electrodes used in electrolysis composite EDM machining are only suitable for processing simple straight round holes . As mentioned before, the blade orifice expansion section is designed into special-shaped complex structures such as dustpan shape, water drop shape, water drop shape, etc. a cat’s ear, etc., in order to better cover the surface of the blade after emitting cold air. and electrochemical treatment is not suitable for special-shaped holes and is destined to be unable to adapt to the inevitable trend of increasing gas turbine inlet temperature.

1.3 Making laser holes

In order to improve the thermal carrying capacity of the blades, high-pressure turbine guide blades and working blades of high-performance aerospace engines need to be covered with thermal barrier coatings. The surface material is usually zirconia ceramic, while traditional EDM and EDM. Electrochemical treatment is only suitable for processing conductive metal materials, the process is formulated as: “first make a hole, then coat”. Using the electron beam physical vapor deposition (EB-PVD) process to coat the surface thermal barrier coating will cause the coating to build up at the orifice, causing problems such as shrinkage and clogging, and the airflow direction will deviate from the design requirements, affecting the effectiveness of the cooling air film coverage[14](Figure 7).

The laser is not selective to the material being processed, allowing it to make single holes on high-temperature alloys with thermal barrier coatings, thereby realizing a new processing method of “coat first then make holes”, which effectively improves the conformity of air film hole design and manufacturing for blades with thermal barrier coating[15-16]. Additionally, the blades after service are affected by impurities such as volcanic ash inhaled through the engine inlet, forming a layer of spinel deposits (CMAS for short) composed of oxides of Ca, Mg, Al and Si at the surface of the blades. In severe cases, it may cause shrinkage holes and clogged holes, and laser treatment can also solve the problem of removing non-conductive CMAS deposits, which is of irreplaceable importance.

Figure 7 Schematic diagram of deviation in airflow injection direction caused by shrinkage cavities in thermal barrier coating

Figure 7. Schematic illustration of jet path deviation induced by hole removal during thermal barrier coating

The quality of the hole production is inseparable from the pulse width of the laser. Nanosecond, picosecond and femtosecond lasers are generally suitable for processing blade air film holes. The duration of a single nanosecond laser pulse is longer than the relaxation time of the electronic lattice. After absorbing laser energy, the electrons transfer more heat to the lattice, resulting in thermally induced defects such as reflow layers on the hole walls. The single pulse duration of the femtosecond laser and narrow pulse width picosecond laser is shorter than the relaxation time of the electronic grating. The electrons absorb the energy and then cannot transfer it to the lattice. Under the action of auxiliary air blowing, the material is peeled off. die to achieve high precision, The effect of “cold working”[17-18]. However, under ultra-strong laser irradiation, the high-density plasma agglomerates in the hole, forming a strong shielding and scattering effect on subsequent lasers, seriously limiting the processing efficiency of small holes with d-ratios. ‘appearance high, and the walls of the hole also tend to form. Wavy, ridge-shaped structure (Figure 8). By adding cutting holes after laser punching, the ridge structure can be eliminated to a certain extent and the roughness of the hole wall can be improved, but this will undoubtedly reduce production efficiency. In contrast, the femtosecond laser and galvanometric system that controls the movement of the light plate are relatively expensive and sensitive to environmental fluctuations in the workplace. We still need to continue working on the equipment and technology to make it suitable for batch processing. manufacturing of blade holes in a factory environment.

Figure 8 Wall profile of precision femtosecond laser cutting hole

Figure 8. Hole wall surface profile by femtosecond laser drilling and finishing

Regardless of the drilling method, some form of energy is applied to the material being processed, so that the material is excited to a higher energy state and then combined with the fluid to transport and remove residue at high energy. the hole. Matching energy application and transportation is the ideal state for making holes. If the transport is stronger than the energy application, the energy must be increased to improve the treatment efficiency; if the energy application is stronger than the transport, energy will accumulate in the hole and thermal defects will inevitably form. For small holes with a high depth-to-diameter ratio, the deeper the hole, the more difficult it is to ensure the above two processes, especially the ability to transport tailings outward. In treatment methods such as electric spark and electrohydraulic beam, it is the use of hollow tubular electrodes that ensures the circulation characteristics of the liquid medium.[19]While laser holemaking uses auxiliary air blowing, the ability to transport residue into the hole decreases rapidly with the increase of holemaking depth, which fundamentally limits the application of laser holemaking. laser holes in small holes with high aspect ratios. The advent of water-guided lasers has solved this bottleneck problem to some extent. The laser propagates by total reflection in the micro-water jet, similar to an optical fiber. The powerful water jet strengthens the circulation flow of the medium in the hole, thus improving the depth to diameter ratio of the hole. It should be noted that water-guided lasers generally use nanosecond light sources, and there is always a recast layer on the hole wall of the treated air film.

In summary, different drilling methods have their own advantages and disadvantages in terms of precision, quality, cost and processing efficiency. Therefore, domestic and foreign researchers have triggered a research boom in composite processing. Long and short pulse laser composite processing is based on two sets of nanosecond and femtosecond laser light sources. The two laser beams share the optical path and coaxial output. In the punching stage, the nanosecond laser is used to achieve rapid perforation. hole repair stage, the femtosecond laser makes it possible to drill holes containing defects. The walls are refined, thus considerably reducing production costs while guaranteeing quality. Laser-EDM hybrid processing also uses the technical route of rapid EDM perforation and fine hole wall repair with femtosecond laser. However, due to differences in processing methods, it is difficult to hold the blades in place for processing, requiring repeated high-precision positioning. to resolve. Zero point positioning tooling is used to avoid positioning errors caused by secondary clamping of blades. Combined with the auxiliary blade posture confirmation system, the repeated positioning accuracy can only be achieved by 0.01mm. In addition, laser drilling can also be used to remove the ceramic coating accumulated on the blade holes from “coating first then making holes”, thus avoiding the problems of removal and hole blocking caused by the processes. traditional, but the principle is that the hole making machine tool has a sufficiently high level of spatial positioning accuracy and accurately transmits the hole coordinates and workpiece posture to the laser equipment.

2. Air film hole post-processing

As mentioned before, the sharp corners of the air film holes form local stress concentrations, which can easily cause the holes to crack during service. Therefore, removing sharp angles from the ports is particularly important to improve blade reliability. External port chamfering can be processed by EDM milling, laser spot path planning, magnetic grinding, abrasive flow, etc. The choice of magnetic needles for magnetic grinding is very important. If the diameter of the needle is too large, the chamfering effect will not be obvious, while if the diameter is too small, it may penetrate the hole or even fall into the internal cavity of the needle. Therefore, the optimization of the magnetic grinding process not only includes the motor speed and processing time, the size and shape of the magnetic needle also have a significant impact on the chamfering effect.[20-21]. Abrasive flow processing is not only suitable for chamfering the outer hole, but also can be used to chamfer the hole on the inner cavity side of the blade, while polishing the surface of the hole wall.[22](Figure 9) However, care must be taken in how to remove the abrasive after processing so that it does not block the internal cavity of the blade and does not form excess material. Therefore, liquid abrasive is more suitable for hollow blades with complex cooling; channels.

The abrasive flow processing process parameters mainly include pressure and time (number of cycles), while the factors that affect the chamfer size also include abrasive viscosity, abrasive particle size and concentration.[23]Since the abrasive flow removes the material in the form of plowing, it has higher requirements on the initial hole opening and hole wall condition. If there are geometric defects such as opening gaps, hole wall edges, steps, etc., the size of the defects can be further enlarged after grinding processing. Additionally, in response to the need to remove the recast layer from the hole wall, chemical grinding can also be used for post-processing.[24]。

Figure 9 Morphology of chamfering of the hole before and after abrasive flow treatment of the hole with air film

Figure 9. Abrasive flow processed hole orifice contour profile comparison

3. Detection of holes in the air film

Air film hole inspection includes two aspects: hole wall quality and geometric size. Hole wall quality inspection mainly relies on cutting metallography method. Generally, the air film hole processing process is defined as a special process, and special process confirmation of the hole making process parameters is required. Metallographic inspection includes recast layer of hole wall, microcracks, heat affected zone, intermittent beads, corrosion/oxide layer, ridges/steps of hole wall, roughness of the wall of the hole, etc.[25]. The geometric dimensions of air film holes include pore diameter, hole position, hole shape, etc. Among them, the diameter of the hole is generally detected using the pass stop method of the pin gauge, but the pin gauge measures the length of the minor axis of the minimum cross section of the hole, which is greatly affected by the roundness and taper of the hole; the hole position is usually detected using the standard prototype visual comparison method, but for blades with high acceptance requirements for hole position accuracy, a five-axis measuring machine equipped An optical imaging probe can be used for inspection.[26]Hole size conformity detection is difficult because the metallographic method is only suitable for observing the profile of a certain cut section, while laser confocal detection is difficult for completely scanning the wall profile, so inspection Small focal length industrial CT becomes the important technical evaluation hole in the manufacturing conformity processes of shaped elements[27]. Additionally, industrial CT is also suitable for wall damage detection. Wall damage includes not only protection against surface damage of the hollow blade sidewall, but also protection of cooling structures such as interior cavity partitions, ribs, and spoiler columns (Figure 10).

Figure 10 The hole wall profile of the special-shaped air film obtained by industrial CT scanning

Figure 10. Contour profile of a shaped hole measured by an industrial CT system　　

The development of sensing technology provides an important basis for realizing adaptive blade processing. Only by accurately collecting the characteristic elements of air film holes can an adjustment processing strategy be formed, thereby compensating for individual differences. There is a casting gap in the turbine blade profile when formulating the adjustment processing strategy, the air film hole jet angle (the angle between the axis of the hole and blade profile) and the relative position between the holes of the air film must be completely. taken into account. The side hole of the inner cavity after adjustment should also be provided. The exit position should avoid cross holes, cross holes, etc. Digital twins provide a technical method for predicting treatment status. The effect of adaptive processing can be checked in the virtual world and then returned to the real world to complete processing after confirmation. This will become an important technology development trend in deep integration. blade manufacturing and inspection in the future.[28]。

4. Conclusion

EDM hole making has low cost and high efficiency, and will long be used as the basic process method for making holes in high temperature alloy blades. Further development includes EDM milling, combination with other process methods and the construction of intelligent systems. electrical machining production lines. Electrochemical hole fabrication is difficult to keep up with the trend of developing special-shaped hole patterns, and its manufacturing capabilities need to be further explored and developed. However, it will still play a decisive role in treating small holes in other areas. With the demand for coated blades, repairing clogged blades after service, and making holes for ceramic-based composite blades, laser processing has become an inevitable choice due to its non-selective nature of the material to be processed. large depth-to-diameter ratios and small Hole processing capacity is insufficient and systematic and in-depth process research needs to be carried out.

Air film hole chamfering has a great impact on the vibration fatigue performance of blades and has good prospects for promotion and application. However, air film hole detection should form a complete standard method system to promote adaptive processing and intelligent manufacturing. technology in the field of blade hole manufacturing.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: How to set the origin and tool length of the workpiece coordinate system of five-axis linkage machining center

Great Light CNC Machining Services 28/12/2024 01:43

In the process of multi-axis machining and five-axis machining, setting the origin of the workpiece coordinate system and the tool length is an important step. If the origin of the workpiece coordinate system and the tool length are set incorrectly, it will cause a tool collision accident, damage the equipment, and the consequences will be disastrous. Therefore, correctly setting the workpiece coordinate system origin and tool length is the first step to ensure safe production. Regarding this issue, there is currently a lack of relevant discussion in textbooks and literature. In particular, in many literatures on “tool setting” of three-axis CNC machine tools, the Z direction value in the G54 memory of the workpiece coordinate system. is mixed with tool length data and is not strictly distinguished. It is not advisable to use a five-axis linkage machine tool with the thought of a three-axis CNC milling machine. Therefore, detailed research and discussion will be conducted below.

In the actual operation of CNC machine tools, to set the workpiece coordinate system and tool length data, you must first understand the concepts of machine tool coordinate system and coordinate system of the room.

Machine tool coordinates are inherent to the machine tool itself and are the only coordinates that can be recognized by the machine tool’s CNC system, while workpiece coordinates are artificial and the machine- CNC tool itself cannot recognize the coordinates of the workpiece.

The essence of the principle of setting the origin of the workpiece coordinate system in a CNC machine tool is to find the value of the origin of the workpiece coordinate system in the machine tool coordinate system and store it in the memory of G54 or G56, G57. , G58, G59 and other instructions. The finding process comes from the fact that many people use cutters as tools to find them, so this process is called “tool setting.”

For example, in Figure 1, point A is the origin of the coordinate system of the machine tool of the CNC milling machine or machining center, and point B is the origin of the workpiece coordinate system . For point B, it has a reading value in the coordinate system of machine tool A. Suppose this value is (X-368.756 Y-367.543 Z-432.843), store this set of values in the memory of , Y, Z in the workpiece coordinate system command G54 or G55, G56, G57, G58, G59, then when executing these instructions, the machine tool will call the values in the X, Y and Z instruction memory to identify the coordinates of the part.

Figure 1 reveals the relationship between the Z value of the workpiece coordinate system origin, the tool length and the machine tool coordinate system origin, which will be explained in detail below .

First of all, you should know that in CNC milling machines and machining centers, tool length refers to the distance from the spindle end to the tool tip, and that the value is always positive. The tool length in the schematic diagram in Figure 1 is 125.524.

As shown in Figure 1, it is known that the origin A of the machine tool coordinate system is at the positive limit position of the three linear axes X, Y and Z, and the origin B of the coordinate system of the room is in the center. of the upper surface of the square piece. Find the tool length and workpiece coordinates. System B is the coordinate system value of machine tool A.

Figure 1 The relationship between the origin of the machine tool coordinate system, the Z value of the origin of the workpiece coordinate system and the length of the tool

In this schematic diagram, “125.524” is the tool length and “-333.189” is the machine’s Z coordinate system reading when the tool cuts just to the top surface of the part. It can be read directly on the screen. of the machine tool, then the value of point B of the workpiece coordinate system. The value of the Z direction value in the coordinate system of machine tool A is:

“-458.713” is stored in Z direction memory in G54 or G56, G57, G58 and G59.

“125.524” is stored in the tool length compensation register and called with “G43 H_”.

Many technicians who operate three-axis CNC milling machines regard “-333.189” as the original Z value of the workpiece coordinate system when setting tools, enter it into the G54 command Z memory, and enter “0 ” in the “H” address of the tool length compensator. In three-axis CNC machine tools, there is another storage method, which is to enter “0” in Z of the G54 command and “-333.189” in the “H” address of the tool length compensator .

These two methods will not affect the position of the tool tip when calling the “G43 H_” instruction, and the position of the tool tip in the Z axis direction is correctly determined. Because in a three-axis CNC milling machine, since there are no rotation axes such as A, B and C, the Z axis is always in a straight state. This storage method does not and will not affect the position of the tool tip. cause tool collision accident. However, in multi-axis machining machine tools and five-axis linkage CNC machine tools, the Z value “-458.713” and tool length “125.524” need to be stored separately and cannot be mixed and grasped like three-axis machine tools, otherwise A, B, C and other rotation axes may occur when linking with the Z axis, and the tool tip tracking function RTCP cannot be performed.

For safety reasons, first measure the tool length, the Z value of the coordinate system of workpiece B in the coordinate system of machine tool A, and finally measure the X and Y values.

3.1 Measure tool length

To measure the length of the tool, two points must be measured. The first point is the end face of the spindle and the second point is the tip of the tool. To measure tool length, you can use a dial gauge, Z-axis adjuster, external tool presetter, etc. It can be measured outside the machine or inside the machine. Off-machine measurement does not take machine tool time and can improve productivity, but it will increase the cost of the off-machine presetter. On-machine measurement takes machine tool usage time and productivity is lower than off-machine measurement, but there is no need to add additional instruments.

3.1.1 Pressing the pin end

As shown in Figure 2, the method of measuring tool length using a dial indicator inside the machine is used. Gently press the dial indicator probe onto the end face of the spindle, let the pointer slowly rotate a small semi-circle, and stop at the “40” position. At this point, find the “relatively real” z coordinate on the machine tool control panel and clear it. The result is shown in Figure 4. For safety reasons and to avoid interference with the tool, you can remove the tool before measuring the end face of the pin before this step.

Figure 2 Using a Dial Indicator to Measure the Pin End Face

Figure 3 Using a Dial Indicator to Measure the Tool Tip

Figure 4 After measuring the end face of the spindle with a dial indicator, the relative coordinates of the Z axis are cleared.

3.1.2 Press the tip of the tool

After measuring the end face of the pin and clearing the count, load the tool, as shown in Figure 3. Use a dial indicator to measure the tip of the tool to find the position of the pin tip. the tool. Let the pointer slowly rotate a small half-circle and stop. to position “40”. At this time, find the “relatively real” z coordinate on the machine tool control panel, as shown in Figure 5. The 179.3999 displayed in the relative Z axis coordinate is the length value of the tool.

In the process of measuring the tool tip, since the probe of the dial indicator is in point-to-point contact with the tool tip, there will be an error in the position of the probe aligned with the tip of the tool. In order to reduce errors, you can use a Z-axis adjuster to measure the spindle end face and tool tip. The Z axis adjustment device is in face-to-face contact, which can greatly reduce errors. The operation process of using a dial indicator is the same as that of the Z-axis adjuster. The difference is that when using the Z-axis adjuster, the pointer of the pressure gauge is pressed to “0”. The tool length measured with the Z-axis adjuster is more accurate, but novices may accidentally overwrite the meter.

The length data of other knives can also be measured in the same way.

3.2 Storage of tool length data

After the tool length data is measured, it is stored in the tool length compensation Z memory. In a three-axis CNC milling machine, the value in the tool length compensation Z memory may be a negative value, but in a five-axis machine tool, the value in the tool length compensation Z memory must be a positive and negative value. values should not be entered, otherwise serious accidents will occur. As shown in Figure 5, the measured tool length data 179.3999 can be input into the length compensation register No. 2. When programming, you can use the T command and the length compensation command tool code G43 to call the tool, for example “T02 M06; G43H2G01Z50.0F500”. When using it, pay attention to the accuracy of coordinates and code to avoid tool collision accidents. .

Figure 5 After measuring the tool tip with a dial indicator, the relative coordinate of the Z axis displays 179.3999

3.3 Measure the Z direction value of the workpiece coordinate system

After the tool length data is measured, the Z direction value of the coordinate system of workpiece B in the coordinate system of machine tool A can be measured. As shown in Figure 6, the spindle rotates at low speed, and the handwheel pulse generator slowly shakes the Z axis downward so that the tool tip just touches the top surface of the workpiece, then s ‘stop. At this time, the coordinate of the machine tool. The Z reading on the machine tool display is “- 49.3801”, this is the number that needs to be memorized. Then the Z direction value of point B in the workpiece coordinate system in the machine tool A coordinate system is: -49.3801-179.3999=-228.78. Then “-228.78” can be stored in Z direction memory in G54 or G56, G57, G58 and G59. As shown in Figure 7, the Z direction value “-228.7800” is stored in register G57.

Figure 7 The Z direction value -228.7800 is stored in register G57

What should be noted here is that “slowly rock the Z axis downward with the handwheel pulse generator so that the tip of the tool just touches the top surface of the part, then stops. Such an operation will result in a significant error. To reduce the error, you can place the Z axis adjuster on the top surface of the workpiece. At this point the spindle cannot rotate. Allow the tip of the tool to slowly press the top surface of the Z-axis adjuster until the adjuster is depressed. the pointer points to “0”. Then, at this time, the distance between the tool tip and the top surface of the workpiece is 50. mm, assuming that the Z value of the machine coordinates is “-10.256” when the pointer of the tool Z axis setting points to “0”, then the Z direction value of point B in the workpiece coordinate system in the machine tool A coordinate system is: – 10.256-179.3999-50.00＝-239.6559 . Therefore, using the Z axis adjuster can improve the measurement accuracy.

In five-axis machine tools, the tool length data and the Z axis data of the workpiece coordinate system should be clearly distinguished and stored separately, and should not be mixed.

3.4 Measure the X and Y values of the center position of the part

After the tool length and degree data and the Z axis data of the workpiece coordinate system are measured, the workpiece center position data can be measured.

If the part coordinate system is centered, the bilateral centering method is commonly used. Scoring tools typically use eccentric mechanical edge finders or electronic edge finders. Centering can be done manually with an eccentric mechanical edge feeler, or automatically with an electronic edge feeler like RENISHAW. The principles of manual centering and automatic centering are the same. The principle of centering is illustrated in Figure 8 and Figure 9. Two points are touched each in the X and Y directions, and the intermediate value is calculated.

Figure 8 Schematic diagram of square centering

Figure 9 Schematic diagram of circular centering

For five-axis linkage machining centers, if the position of the table rotation center has been found when debugging the machine tool, it can be used directly without re-searching.

After obtaining the X and Y position data of the zero point of the workpiece coordinate system, it can be stored in the X and Y memory of G54 or G56, G57, G58 and G59. In a five-axis linkage machining center, various tool length data must be stored in the tool length compensation register, and various data and programming codes must be used jointly, otherwise serious tool accidents Tool collision will occur.

In MDI operation mode, run the following program in one block: When running the above program, the fast forward should be set to a slower state. The operator must observe at all times whether the position of the tool tip is correct. make predictions and react immediately if problems arise. The expected tool tip of this program should stop at a position 50 mm above the center of the part. If not, check the reason.

The essence of the principle of setting the origin of the workpiece coordinate system in a five-axis machining center is to find the value of the origin of the workpiece coordinate system in the coordinate system of the machine tool and to store it in the memory of G54 or G56. , G57, G58, G59 and other instructions. The tool length compensation value cannot be mixed with the Z value of the workpiece coordinate system. The tool length compensation value and the Z value of the workpiece coordinate system must be stored separately. Measuring with a Z-axis adjuster will be more accurate. The measured data should be checked before use. The method presented in this article has been verified correctly on domestic and foreign major five-axis CNC machine tools and is universal. The five-axis linkage CNC machine tools that have been verified include German Demag machine tools (SIEMENS CNC system), Swiss Mikron GF machine tools (HEIDENHAIN CNC system), Wuhan Hi-Tech machine tools (SIEMENS CNC system). CNC Huazhong), etc.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: Introduction to Laser Cleaning Technology

Great Light CNC Machining Services 28/12/2024 00:41

Laser cleaning is a technology that uses high-energy laser beams to remove contaminants from the surface of materials. Its working principle mainly relies on the thermal effect, photochemical effect and shock wave effect caused by the interaction between the laser and the material. When the laser beam irradiates the material surface, the contaminants absorb the laser energy and quickly heat up, expand, vaporize or peel off, thereby achieving cleaning. It can remove rust, paint, oil and other pollutants on the surface of various materials and is widely used in aerospace, automobile manufacturing, cultural relics protection and other fields. Since the laser can be transmitted via optical fiber, its use is very flexible. It can be used to explore dead ends or difficult to eliminate areas via optical fiber, making it more flexible.

Compared with traditional cleaning methods, laser cleaning has obvious advantages:

Non-contact cleaning: As a non-contact cleaning technology, laser cleaning can effectively remove contaminants on the surface of cultural relics, such as soil, dirt, rust, etc., without causing physical damage to the relics cultural themselves.

Selective cleaning: Laser cleaning technology is selective and can adjust laser parameters according to the absorption characteristics of different materials and contaminants to achieve precise removal of contaminants on the surface of cultural relics while protecting the cultural relics themselves. -themselves.

Environmentally friendly: Laser cleaning does not require the use of chemical cleaning agents, avoiding chemical pollution and potential damage to cultural relics. This is a green and environmentally friendly cleaning method.

Applicable to a variety of materials: Laser cleaning technology is suitable for cleaning cultural relics of almost all materials such as organic materials, inorganic materials and metals, providing a multi-functional solution.

Improve cleaning efficiency: Laser cleaning can quickly remove contaminants and improve the efficiency of restoration and protection of cultural relics.

Precision control: The laser cleaning system can realize precise energy control and positioning, and is especially suitable for processing the surface of cultural relics with complex shapes or fine details.

Safety: Laser cleaning equipment is usually equipped with safety controls to ensure safety during operation.

Consulting material telephone number: 13522079385

Although laser cleaning technology has many advantages, it still faces some challenges in its practical applications. First of all, technological cost is an important limiting factor. The current cost of laser cleaning equipment is relatively high, which limits their widespread application in some fields. Second, promoting technology is also a challenge. As an emerging cleaning method, laser cleaning needs to continuously accumulate experience in practical applications and improve user awareness. In addition, the imperfection of industrial standards also limits the application of laser cleaning technology in some fields, and it is necessary to accelerate the formulation and improvement of relevant standards and specifications.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: Key Production Factors of Integrated Die Casting Technology

Great Light CNC Machining Services 27/12/2024 23:39

In July 2019, Tesla issued a new patent titled “Multi-directional body-integrated molding machine and related molding methods for automobile frames”, proposing frame-integrated molding technology and related molding machine design. At the Tesla Battery Day conference on September 22, 2020, Musk said that the Tesla Model Y will use integrated die-casting to produce the body’s rear floor assembly, replacing the initial need for more than 70 parts and more than 1,000 welds, Tesla officials said. that this technology will reduce the quality of the lower body assembly by 30%, reduce the manufacturing cost by 40%, save 20% of the cost of Model Y vehicle, and reduce the manufacturing cost by 30%. At the same time, Tesla plans to use three large die-cast parts to assemble the entire lower body and replace the original 370 parts, which could reduce the overall quality of the vehicle by 10% and increase the autonomy of 14%. Tesla led the entire industry to follow and change. OEMs and die casting related manufacturers such as NIO, Xpeng and Gaohe are currently carrying out 0 to 1 verification work and 1 to 100 development work. Volvo, Volkswagen, Mercedes-Benz Traditional. OEMs such as FAW and FAW are also actively deploying.

The technology mentioned above is “integrated die casting technology”. It redesigns and heavily integrates dozens or even hundreds of parts that need to be assembled into the original design. It uses a very large tonnage die-casting machine and advanced technologies. casting technology to form super large size die casting machine to achieve original functionality. The most important feature of this technology is the ultra-large size of products, which leads to ultra-large tonnage die casting machines, ultra-large complex structural molds, extreme process parameters and demanding requirements. extremely high CAE analysis ratings. it also solves the problem of deformation of large, thin-walled parts. Heat-treated aluminum alloy has become one of the hot spots of integrated die-casting technology.

This article combines traditional die casting technology with a detailed introduction and analysis of the production factors of integrated die casting technology, namely “people, machines, materials, methods, environment and measure “.

Material properties

Integrated die-casting parts generally have the characteristics of large size, thin wall thickness and complex structure, which imposes higher requirements on the performance of aluminum alloy materials. Taking into account factors such as performance, process characteristics and production conditions, die-casting aluminum alloy integrated materials not only have higher overall performance requirements than ordinary die-casting, but have also unique requirements.

1. General performance requirements

Good thermoplastic rheological properties: It must have good thermoplastic rheological properties when the superheat is not higher than the liquid and solidus temperatures to achieve the filling of complex cavities, form a good casting surface and avoid the appearance of defects. withdrawal.

Lower linear shrinkage avoids cracking and warping during the die casting process, allowing die casting parts to maintain high dimensional accuracy.

The smaller solidification temperature range facilitates rapid simultaneous solidification and reduces defects such as internal shrinkage holes.

Better casting interface (mold) properties will not cause chemical reaction with the die casting mold and have low affinity to reduce mold sticking and mutual alloying.

2. Unique performance requirements

(1) High strength and toughness For traditional aluminum alloys, heat treatment is a necessary way to ensure the mechanical properties of parts. However, in fact, the heat treatment process can easily cause surface defects and dimensional deformation of parts, which will be a problem. problem for large built-in parts. This will inevitably lead to an increase in scrap rate and bring huge cost risks. Therefore, special heat-treatable aluminum alloys are required to ensure that the material maintains good mechanical properties after being formed without heat treatment. The structural design of parts is carried out according to the strength of the material, and the higher the strength of the material, the more obvious the weight reduction. Additionally, for vehicle body structural parts, crash and fatigue performance requirements must also be considered. Therefore, integrated die-cast structural parts require materials with high strength and plasticity in the cast state.

(2) Excellent casting performance includes many aspects for integrated die-cast structural parts, the mold filling ability of the material is essential. At present, the farthest process can reach about 2.7 m. If the mold filling capacity is insufficient, it will cause problems such as under-pouring.

(3) High connection tolerance Since large integrated die-casting body structural parts cannot achieve uniform performance in different parts of the part, different connection methods can be selected in different parts of the part. For example: welding, SPR and bonding, etc.

Different connection methods also have different performance requirements for materials. For example, SPR requires the material to have high toughness, while welding requires the material to be pore-free.

(4) Higher tolerance of trace elements and impurities. Currently, the yield of integrated castings is around 60% (each company’s data is inconsistent, this data is a rough average), which means that around 40% of parts are affected. must be returned to the oven for reuse. In this process, some impurity elements will inevitably be introduced, and some elements will also be burned. With the determination of the double carbon goal, it is hoped that in the future, recycled materials can be integrated into the production process without heat. Therefore, the material must have a high tolerance to elements and impurities to ensure casting economy and performance.

(5) Durable and efficient modifier Due to the characteristics of heat-free materials, the heat treatment process is eliminated. The currently commonly used AlSi10MnMg material improves the mechanical properties of parts through heat treatment. However, materials without heat treatment have no means of tracking and can only acquire mechanical properties through the structure formed during the casting process. The strength and plasticity of materials are achieved by controlling the structure formed during solidification. At present, the key point for controlling the structure of materials without heat treatment lies in controlling the eutectic structure. Aluminum-silicon alloys focus on controlling the morphology and size of the eutectic silicon; Aluminum-magnesium-silicon alloys focus on controlling the morphology and size of magnesium disilicon. Currently, the element lanthanum (La), the element gadolinium (Gd) or the existing rare earth element is used as a modifier for tissue regulation. In the actual production process, the process requires the melted material to be kept hot for a long time. If the efficiency of the modifier decreases or even fails, it will pose a great challenge to the continuity of production.

Therefore, aluminum alloys without heat treatment have become the only choice for integrated die casting products. Major universities, scientific research institutes, enterprises and institutions have developed materials resistant to heat treatment, showing a flourishing trend. At present, heat-treatable aluminum alloys can be divided into two categories: aluminum-silicon series (Al-Si series) and aluminum-magnesium series (Al-Mg series) within this framework. . At present, mature materials without heat treatment often have a non-heat treatment alloy quality system, such as Alcoa, Rheinfield, Tesla and Shanghai Jiaotong University.

By sorting the components of different grades of heat-treatable aluminum alloy materials, it can be seen that some materials have been refined in their composition and production process based on existing patents. Companies that have successfully developed heat-treatable aluminum alloy materials. will apply for patents as soon as possible for protection; OEMs To avoid patent disputes, patent-protected alloy grades will be selected. Patents are the threshold for preliminary testing and certification of complete vehicles. Barriers to R&D and certification – Although there is no unattainable technical threshold for research and development of alloys without heat treatment, it requires cooperation between upstream materials companies, die casting plants pressure, mold factories and automobile manufacturers for R&D. The obstacles to R&D lie not only in adjusting alloy composition and adjusting process routes. The bottom line is that material manufacturers cooperate with die-casting plants and automobile manufacturers to continually conduct trial and error to produce materials that meet vehicle performance requirements.

Process flow

Integrated die-casting technology changes the traditional body production process (produce the structural parts first, then weld and assemble them), which can greatly reduce welding and gluing links and greatly simplify the overall process bodywork production. Integrated die casting parts mainly include processes such as melting, die casting, grinding, X-ray machine assembly and machining. The production process is shown in Figure 1. Compared to body structural parts such as shock towers and longitudinal beams, heat treatment. is omitted (orthopedic process), this section focuses on the die casting process.

Integrated die-cast parts include the rear wheelhouse interior panels on the left and right sides of the vehicle, rear longitudinal beams, floor connection plates and interior beam reinforcement plates. They are larger and more complex in shape than ordinary die castings. with different shapes, sections and materials, thick changes are more dramatic. It also puts forward higher requirements for the die casting process: the flow pattern, specific injection pressure and process speed are more strictly controlled, as well as the requirements for precision and threshold of the equipment and the ability of the mold to resist shock. the deformations are stricter.

The integrated die casting process includes: spraying, mold clamping, pouring, injection, pressure holding, mold opening, picking up, integrity inspection, cooling, trimming and conveyor belt.

The die casting process parameters mainly include pressure, speed, time, temperature and vacuum. The casting pressure is 80 MPa for airtight products, 60 MPa for general products, and all integrated die casting products are less than 40 MPa. The reason is that the pressure is too high and the clamping force is insufficient, resulting in serious material leakage. the air pressure injection speed of the die casting machine generally requires more than 10m/s, the actual maximum speed of the punch is 6-8m/s, the speed of the inner door. It is 40 to 55 m/s; the filling time is 50 to 80 ms; aluminum liquid temperature is 700-710℃, mold temperature is 220-280℃, integrated die casting has high requirements for mold heat balance; vacuum degree is 30~50 mbar (1 bar = 105 Pa), actually can be less than 30 mbar.

In addition, because the precrystallized structure greatly weakens the mechanical properties of integrated die casting parts, the casting process of aluminum alloy is very critical. Precrystallization is usually controlled by processes such as the temperature of the molten aluminum during melting. cup, barrel heating and die casting process.

Basic material

The size and quality of integrated die casting structural parts continue to improve, and the tonnage of die casting machines reaches new heights. Integrated die-casting technology adopts die-casting hosts with a capacity of more than 6,000 tons. -The die casting machines that have been installed and debugged so far include 6000t, 6100t, 6600t, 6800t, 7200t, 8800t and 9000t. In addition to 12,000 t, another 16,000 t die casting machine has entered production. scene, 20 000 ton die casting machine enters the development stage.

1. Die casting machine

The die casting machine is an industrial casting machine that hydraulically injects molten metal into a die mold to cool and form it. Once the mold is opened, a solid metal casting is primarily obtained. producing a variety of parts and components by installing different die casting molds. According to industry experience, die casting machines of different tonnages are generally selected according to the contour, size and quality of die casting parts. According to Bühler China, the tonnage of die-casting machines required for traditional body parts has remained in the range of 1,600-4,400t for a long time, of which the front shock absorber tower requires 1,600-2,500t, while the The front shock absorber and rear door frames, tailgate boxes, rear longitudinal beams and A-pillars require 4,000 t. Door requirements are 4,400 t. As the size and quality of integrated die-casting structural parts continue to increase, the requirements for the tonnage of the die-casting machine also increase, as shown in Figure 2, the mid-size SUV model. The rear floor and front cabin of the Y use a 6,000t die-casting machine; the half-piece rear floor of Weilai ET5 B-class coupe uses a 6,000t die-casting machine; and the rear floor (or front floor) of the largest electric Cybertruck pickup will use 8,000; up to 9,000 t Die casting machines; battery packs, A00 level lower body, etc. require die casting machines with a tonnage of 12,000 t and more.

There are difficulties in the research, development and production of ultra-large die casting machines. The difficulty of manufacturing ultra-large die casting machines is mainly reflected in the two aspects of research, development and production.

In terms of research and development, the currently widely used automotive aluminum die-casting structural parts have the characteristics of large size (500~1500mm), thin wall (about 2.5mm), ‘a complex structure, etc., which combine traditional aluminum castings. Cast structural parts with highly integrated one-piece die-cast structures. In contrast, the shape of the integrated die-casting structural parts is more complex, the wall thickness is uneven, and the size and mass are greatly increased. This affects the clamping force, mold gap size, injection force, maximum air injection speed and. safety of the very large die casting machine. It places higher demands on design capabilities for performance and reliability. Previously, die casting machine manufacturers only had experience in the research and development of die casting machines under 5,000t. Facing the growth of tonnage of ultra-large die casting machines, 6,000t→7,000t→8,000t→9,000t→. 12,000t → 16,000t → 20,000t, the R&D curve of die casting machine factory is very steep.

In terms of production, the time from research and development to delivery of ultra-large die casting machines is long, and die casting machine factories need to continue to invest large sums, which tests in a to some extent production capacities. die casting machine factories. Domestic die-casting machine factories lead in layout, and Lijin Group is far ahead in order volume.

Domestic die casting machine manufacturers are leaders in research and development progress, delivery speed and order volume. The representative companies are Lijin Co., Ltd. (13522079385), Yizumi (18210062835) and Haitian Metal (15910974236).

Among them, Lijin Group delivered its first large-scale die casting unit of 6,000 tons as early as November 2019 and successfully became a global supplier of Tesla. Later, he received orders for 30 sets of ultra-large die-casting machines from Tesla. After that, Lijin Group continued to receive ultra-large integrated die casting orders from various domestic die casting factories, and the tonnage of its delivered die casting machines continued to break new highs. Foreign die casting machine factories are progressing slowly and will only officially deliver a 6,100 ton die casting machine to customers in June 2022.

2. Die casting mold

Die casting molds are also one of the basic equipment in die casting production. Integrated die casting places higher demands on the design of large-scale die casting molds. The size of the integrated die casting mold is larger. The product size of traditional die casting mold is less than 1m. The size of the integrated die casting product reaches 1.6~2m, and the corresponding mold size should be. more than 3 m, which leads to increased processing difficulty. The quality of integrated die casting mold reaches 150t or more. The vacuum die casting environment and integrated die casting have high requirements for mold sealing performance. The required vacuum environment is less than 30 MPa. Due to the large number of mold parts, the requirements for sealing rings are higher; The development cycle is long and the development cost is higher. The development cycle of very large die casting molds is 150-180 days. The cost of traditional die casting molds does not exceed 4 million yuan, and the cost of very large molds. die casting molds generally cost more than 10 million yuan. The molds are highly personalized and orders are generally accepted as private customization. They need to be designed according to different car models, which requires the mold factory to constantly communicate with the car manufacturer and the die casting factory, for design, proofing and improvement. and optimization, and production. The cycle is long and the level of reuse of design solutions is low. , usually the second mold needs to be redeveloped; the material performance requirements are high, because the injection speed of the large die casting machine is faster, the mold needs to withstand greater pressure, and secondly, the quenching performance, toughness, and Thermal expansion coefficient requirements of the material are high, as well as surface treatment and other technologies are difficult.

Support Equipment

In addition to die casting machine and die casting mold, other equipment involved in die casting production is called supporting equipment. It mainly includes peripheral equipment, melting equipment, heat treatment and post-processing equipment, among which post-processing includes machining, surface treatment and assembly, etc. The peripheral equipment, together with the die casting machine and the die casting mold, form a die casting unit. The peripheral equipment includes machine side oven, spray system and spray robot, picking robot, vacuum system, integrity inspection and cooling. water tank, slag removal bag, trimmer and coding machine, conveyor belt. , mold temperature controllers, cooling stations, thermal imagers and dust hoods, and more than 20 sets of melting equipment including centralized melting furnaces, transfer sets, metering furnaces, holding furnaces and post-processing machines including machining, deburring, surface treatment and assembly equipment. Among the above equipment, the difference between integrated die casting technology and traditional die casting technology lies in the machine side oven, spray system, thermal camera, trimming equipment and equipment machining.

1. Machine side oven

There are two types of ovens on the machine side: the dosing oven and the holding oven + soup feeder. Generally, a dedicated centralized melting furnace is equipped alongside the two. The dosing oven is characterized by a large, fully enclosed dosing system. The fully enclosed laundromat adopts a closed design, so that the aluminum liquid is no longer in contact with the air during the soup feeding process, and the soup feeding time is greatly reduced. should be equipped with 4-8 ton dosing furnace, single/double pump can provide soup volume of 150/200 kg, dosing speed of 10 kg/s and dosing accuracy of ±1% . In addition, the metering furnace is divided into three types: integrated sealed air pressure metering holding furnace, split open air pressure metering holding furnace and split open air vacuum metering holding furnace. Relatively speaking, the holding furnace + soup feeding machine has disadvantages in work efficiency, energy consumption, combustion loss and soup feeding time, but the investment in equipment is weak. Currently, both types of machine-side furnaces are used, as shown in Figure 3.

2. Spray system

Most use micro-spray or electrostatic spray technology, using pulse spray technology, equipped with profiling nozzles and multi-spray devices, as shown in Figure 4.

Spraying is a large cycle time hog and traditional spraying methods seriously affect the efficiency of producing large parts. The design of a set of movable and fixed molds or double spraying on one side is adopted to minimize the installation and maintenance area and avoid further mechanical interference. In terms of technical solutions, micro-spraying or electrostatic spraying technology can be selected to reduce the cycle time and improve production efficiency to the greatest extent, but it also imposes higher requirements on the control of the thermal balance of the molds.

3. Thermal imager

As shown in Figure 5, the integrated die casting is basically equipped with a real-time online mold temperature monitoring system, including infrared thermal cameras, monitoring systems, acquisition software and temperature analysis, etc., which work with mold temperature machines, spot coolers and spray robots to adjust and control the mold temperature.

During the die casting production process, the mold temperature real-time online monitoring system is connected with the control system of the die casting machine, and can also communicate with other peripheral equipment such as spray robots, mold temperature controllers and spot coolers to complete closed-loop control. The monitoring system can accurately and quickly collect, record, analyze and compare the mold surface temperature with the set value during the two stages of mold opening and spraying, and complete the corresponding evaluation, thereby precisely controlling the mold temperature to achieve the stabilization objective. the mold temperature should ultimately achieve stable production processes and stable product quality.

4. Paring plan

Integrated die casting generally uses plasma cutting machine + edge cutting machine, plasma cutting is used in the small batch stage, and edge cutting machine is used in the mass production stage. Trimmer solutions involved in die casting production include trimmers, plasma, lasers, high-speed saws and manual labor, as shown in Figure 6.

The speed of hydraulic edge trimming machine is relatively faster, but a certain margin should be left to control the deformation, and the investment is large, so it is more suitable for mass production, the cutting performance is similar to those of the laser; , or even slightly better, and the total price of the equipment It is low, has high versatility and flexibility. All kinds of castings with complex shapes can be processed on the same equipment, but the consumables are more expensive; Light cutting is more common in small batch production in Europe. The advantage is that the cuts are clean, except for the corners, great versatility and flexibility. However, the cutting cost is high and is suitable for cutting thicknesses less than 10mm; -rapid sawing can be used on thin-walled workpieces. It is easy to cause product deformation due to stress; Manual edge trimming is more suitable for traditional small die-casting parts in small and medium-sized die-casting factories.

5. Machining solutions

There are currently largeHorizontalFive-axis machining centerAndFive-axis double gantry machining centerconsultation phone: 13501282025.

The processing characteristics of large-scale integrated die casting parts: large-size stroke is more than 2000mm; there are many processing points, but the processing volume of a single point is mainly drilling, tapping, etc. and there are many spatial angle holes. The specific selection should be based on factors such as product characteristics, order volume, investment funds, etc. In addition, in order to improve processing flexibility and reduce investment costs, using robotic clamping tools to process integrated die-casting parts has become another goal. There are already mature cases of robotic processing of interior door panels. overall rigidity of the robot, there is no such case yet. Applied to integrated die casting products.

Testing process

Compared with other die casting products, the testing of integrated die casting products is nothing special, which mainly includes six types: appearance quality, defect detection, outline size, mechanical properties, temperature testing. bench and road tests. Among them, appearance quality refers to cold sealing, flow marks, deformation and cracks; Defect detection mainly checks internal defects such as pores, shrinkage cavities, inclusions, etc. ; , elongation); outline dimensions involve inspection tools, three-dimensional coordinates, etc. ; Bench tests include static strength in different directions, durability performance under real working conditions, and road crash tests mainly include: Performance test (test acceleration, climbing, starting and maximum speed vehicle and other performance indicators), braking performance test (testing the vehicle braking distance, brake force distribution and braking stability and other indicators), handling performance test ( test the vehicle’s handling performance, such as driving in bends, bends and merges, etc.) and reliability testing (testing the vehicle’s driving performance in different road conditions and the reliability of the components).

Staff quality

Integrated die casting technology imposes high-level comprehensive requirements on R&D, technology and on-site personnel, involving four major aspects: product design, material development, processing molds and production management. site.

Product design requires reserves of knowledge in structural mechanics, vehicle structure, mechanical drawing, Catia, Abqus, etc. Materials development requires mastery of solidification principles, alloy formulas, basic knowledge of materials mechanics, etc. In terms of process molds, you have mastery of fluid mechanics, process parameters and casting systems, mold design, thermodynamics and surface treatment technology, etc. On-site management has many skills such as familiarity with equipment operation, electrical/hydraulics, automation programming, lean production, quality management and staff training. .

There are only more than 300,000 employees in the die casting industry. It is a niche industry, but it is also a typical multidisciplinary field that has comprehensive requirements for employee knowledge reserves and practical on-site operations. Integrated die casting technology will be improved by several orders of magnitude.

Conclusion

Integrated die casting technology is basically a die casting technology supporting a vacuum system, as well as the characteristics of oversized products. It is always an improvement and expansion of traditional technology. However, oversized sizes have moved the entire industrial chain from quantitative to. qualitative changes.

Before that, the maximum tonnage of die casting machines had been at the level of 4,000 tons for more than 20 years, while highly integrated die casting products continued to touch the tonnage ceiling and have been under development since 20 years old. 000 ton die casting machine, with the subsequent increase of equipment processing difficulty and control precision; in the die casting process of large products, the filling distance exceeds 2m, and the casting and drainage system is particularly important; the quality is above 100kg and the filling time is tens of milliseconds, the process window has been greatly reduced, and high requirements have been put forward for equipment performance, mold level and quality staff; to meet the comprehensive requirements of medium strength, high elongation, no need for heat treatment, good casting performance and low cost.

Therefore, the promotion and application of integrated die casting technology requires the collaborative cooperation of multiple industries and the whole chain, including automobiles, equipment, die casting, molds, materials and scientific research, to contribute to a soft landing of integrated die casting. .

Authors: Yu Deshui (1), He Tingyu (2), Liu Qing (1) Li Dongyang (1), Gao Jie (3), Han Xing (4)

(1) Suzhou Yadelin Co., Ltd.

(2) Dongguan Pingze Hardware Products Co., Ltd.

(3) BYD Co., Ltd.

(4) Shandong Hongqiao Lightweight Technology Co., Ltd.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: Improve the precision and rigidity of machine tool spindle bearings

Great Light CNC Machining Services 27/12/2024 22:38

Bearings used in machine tool spindles are divided into two categories: roller bearings and plain bearings. From the perspective of rotation accuracy, both types of bearings can meet the requirements, but compared to their performance indicators, plain bearings are better than plain bearings. The advantages of bearings are as follows: (1) Bearings can work stably under large conditions. speed and load changes. (2) Bearings can operate without clearance or even under preload (with some interference). (3) The friction coefficient of bearings is low, which helps reduce heat generation. (4) The bearings are easy to lubricate and grease can be used. Grease cannot be replaced until it has been repaired. If oil is used for lubrication, the amount of oil required per unit time is also much less than that of plain bearings. The disadvantages of bearings are: (1) The number of rolling elements is limited, so the radial stiffness of the bearing changes during rotation, which is one of the causes of vibration. (2) Bearing damping is low. (3) The radial size of the bearing is larger than that of the sliding shaft.

Under normal circumstances, machine tools should try to use bearings, especially most vertical spindles. Bearings can be lubricated with grease to prevent oil leakage. Plain bearings are only used on machine tools with low surface roughness and horizontal spindles, such as cylindrical grinders, surface grinders and high-precision lathes, etc. Bearing accuracy and stiffness directly affect spindle rotation accuracy, which are explained separately below.

Although bearings have a series of advantages and have been widely used in mechanical equipment, plain bearings need to be used in situations such as high speed, high precision, heavy load and structural requirements. Indeed, plain bearings have certain characteristics than rolling bearings. cannot replace. Its main advantages are: simple structure, convenient manufacturing, assembly and disassembly; good shock resistance and vibration absorption performance, smooth operation, high rotation precision and long service life. Its main disadvantages are: complex maintenance and high requirements for lubrication conditions. When the bearing is in a state of limit lubrication, friction and wear are significant.

Plain bearings are mainly composed of bearing seats and bushings. They are mainly divided into radial plain bearings (also called radial plain bearings), thrust plain bearings and radial thrust plain bearings according to the direction of the load, they are divided into liquid lubricated plain bearings; bearings according to the lubrication state, gas lubricated bearings, mixed lubricated bearings, solid lubricated bearings and non-lubricated bearings according to the rolling method, they are divided into lubricated mold bearings, direct contact bearings and others; bearing plain bearings. The backing pad is the main part of the sliding bearing. When designing the bearing, in addition to selecting the appropriate backing pad material, the structure of the backing pad should also be designed reasonably, otherwise the operating performance of the sliding bearing will be affected.

Due to their own structural factors, ordinary plain bearings are prone to low oil film rigidity, short precision maintenance period, difficult maintenance, high processing surface roughness and marks. vibration evident during production. Practice has proven that when the spindle plain bearing is selected as the liquid friction plain bearing, it has higher precision and rigidity, and the processing quality and productivity can be improved.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

CNC Knowledge: Small grinding head polishing. Stress disk polishing. Magnetorheological polishing.

Great Light CNC Machining Services 27/12/2024 21:34

Small grinding head polishing. Stress disk polishing. Magnetorheological polishing.

1. Small grinding head polishing technology:

The part is polished using a grinding head much smaller than the diameter of the part. The amount of material removed is controlled by controlling the residence time of the grinding head at different locations on the workpiece surface and the pressure between the grinding head and. the workpiece.

This technology was first proposed by the American company Itek, and then gradually used in industrial manufacturing. The typical 2.4m diameter primary mirror of the Hubble Space Telescope in the United States is polished by CCOS, and the final surface precision reaches 12nm RMS.

Due to the use of computer control to replace manual experience, small grinding head technology enables optical processing to get rid of traditional manual grinding and polishing. The polishing process is stable and highly certain. Therefore, the processing efficiency and precision are also high. which can significantly shorten the processing cycle of large diameter optical components.

At the same time, small grinding head technology is simple in principle, inexpensive, easy to implement, and can be replaced with grinding heads of different sizes according to actual needs, so it has been widely used in processing large grinding heads. diameter optical components.

However, the technology of small grinding heads is still contact machining, which has some disadvantages such as edge effect, polishing disc wear and underground damage. At the same time, because the polishing disc is a rigid disc, it cannot fit well with the polishing disc. mirror surface when processing aspherical surfaces, which is easy to produce medium and high frequency errors.

2. Stress Polishing (SLP):

An aspherical surface treatment method developed based on the principle of stress deformation of thin plates. When polishing aspherical parts, the shape of the stress disk can be changed in real time to obtain the required surface shape through computer control, thereby achieving full contact between the polishing disk. and the mirrored surface of the room combine. SLP overcomes the disadvantage that the small grinding head polishing disc is a rigid disc which cannot completely adapt to the aspherical surface. This is a development and complement to small grinding head technology.

This technology was proposed in the early 1990s by the Large Mirror Laboratory at the Stiva Observatory at the University of Arizona. We have also successfully developed a stress disk polishing machine tool, which can process workpieces with a diameter of up to Φ8.0m, and the effective diameter of the stress disk is Φ1.2m. This equipment was used to process a series of large mirrors, among others. : 1.8 mf/1.0 VATT (Lennon Telescope) primary mirror, 3.5 mf/1.5 SOR primary lens, 6.5 mf/1.25 Multi-Mirror Telescope (MMT) primary lens, and primary lens 6.5 mf/1.25 Magellan primary mirror.

Compared with small grinding head technology, SLP technology is more suitable for processing large diameter optical components due to the larger strain disk diameter and high removal efficiency. When processing aspherical surfaces, the grinding head can closely fit the workpiece surface. will not produce medium and high frequency errors. However, because SLP technology, like small grinding head technology, is also a contact processing method, it also has disadvantages such as edge effects and underground damage.

In addition, when processing aspherical surfaces, the surface shape of the stress disk needs to change in real time according to the shape of the workpiece, which also requires high control technology.

3. Magnetorheological finishing technology (magnetorheological finishing, MRF):

In the early 1990s, the COM Center in the United States proposed this technology which combines electromagnetic and fluid mechanics theories and uses the rheological characteristics of magnetorheological fluid in a magnetic field to polish optical components.

MRF does not have a polishing disk and uses the shear force between the magnetorheological fluid and the workpiece to remove material. The positive pressure on the workpiece is very small, so there are no disadvantages such as polishing disc wear and underground damage during contact polishing. method.

However, due to the large size of the MRF polishing wheel, the removal efficiency is sensitive to the polishing distance, so it is not suitable for polishing very steep concave surfaces and internal cavity components of large diameter.

4. Hood polishing technology:

Use a special flexible airbag with online controllable air pressure. The shape of the airbag is a spherical crown, and a special flexible polyurethane polishing pad or polishing cloth is attached to the outside of the airbag.

This technology was proposed by the Optics Laboratory of the University of London in the 1990s to solve the problem of inconsistency between the aspherical polishing disk and the aspherical surface.

The airbag has a flexible structure and adapts well to the workpiece; the material is removed evenly in the polishing area, the process is well controllable, etc. Therefore, this method can easily process optical devices with high precision and high surface quality. In recent years, the development direction of airbag polishing technology is to improve processing efficiency, reduce edge effects, and eliminate medium and high frequency errors.

5. Ion beam calculation (IBF):

Under vacuum conditions, inert gases such as argon (Ar), krypton (Kr), and xenon (Xe) are ionized via an ion source to produce an ion beam with a certain energy that bombards the surface of the room. Reaching the surface of the part, it will exchange energy with the atoms of the part’s material. When the atoms on the surface of the part gain enough energy to escape the binding energy of the material surface, they break away from the material surface. workpiece, thus removing material.

As early as 1965, the American Meinel discovered the phenomenon of elimination of optical materials under the action of ion beams. However, the energy density of the narrow beam high-energy ion source used at the time was too high, so the mirror was unusable. burned in a short time, making it difficult to control the energy. The emission density and removal efficiency of the treatment are very low, so there has been no progress in use for a long time. It was not until the late 1970s that the emergence of the wide-beam, low-energy Kaufman ion source made this technology available. It not only limited the ion energy to the range of 300 to 1500 eV without damaging the optical mirror, but it also limited the ion energy to the range of 300 to 1500 eV. also improved the efficiency of ion beam processing, so that ion beam technology began to be formally applied to the processing of optical components.

For the above 5 types of processing equipment, please contact: 13522079385

Ion beam polishing technology has the following advantages:

Non-contact processing: During processing, the ion beam has no mechanical force on the surface of the workpiece, so it will not cause underground damage to the workpiece. At the same time, the shape and removal efficiency of the removal function will not change at the edge of the workpiece, so there is no edge effect.

High processing precision and good surface finish: processing is carried out under the precise control of computers and interferometers. In theory, the processing precision can exceed the atomic level. The treatment environment is stable, the ion beam generated by the ion source is weak. fluctuations, and there will be no wear on the surface of the part.

Gaussian suppression function: Compared with several other polishing methods, the suppression function is closest to the Gaussian distribution, which is convenient for solving the residence time distribution.

The shrinkage function has good robustness: ion beam polishing is carried out under vacuum, the shrinkage function has good controllability and stability, and is suitable for processing large diameter optical components;

Wide applicability of surface shape: During ion beam polishing, the ion beam flow is always in close contact with the workpiece surface, and there will be no medium and high frequency errors caused by the mismatch between the polishing tool and the mirror surface. it is suitable for processing spherical and aspherical surfaces, in particular. This involves high-precision machining of very stiff aspherical surfaces;

Wide range of application materials: Processing materials generally include metals, ceramics and precious stones. Typical examples include 316L stainless steel, AZI magnesium alloy, high temperature alloys, high speed steel, W6M05Cr4V2 high speed steel, composite nitride hard coating and. DLC.

To summarize:

For large diameter optical components that have high requirements for surface precision, it is always difficult to process them with high precision using a single method. Generally, different processing methods need to be combined and selected based on the amplitude distribution and frequency band. surface shape residue during the treatment process. When the residual surface shape is small and quickly approaches the target value, ion beam polishing is used for final high-precision polishing.

Judging excellent processing capabilities: a brief analysis of key processes and indicators

Above we have mentioned many relevant figures and indicators when introducing different processing technologies. Here we will briefly present some important impact indicators.

Type of treatment:

Treatment of aspherical surfaces: Generally speaking, aspherical surfaces are other surfaces excluding spheres and planes. From the application point of view, aspherical surfaces can be divided into aspherical surfaces with axial symmetry, aspherical surfaces with two symmetrical surfaces and without free symmetrical surfaces. shaped surface (spectacle lenses). The difficulty in treating aspherical surfaces is that there is no fixed and universal function expression on the surface. The spherical functions corresponding to different application scenarios may be different, which can be called free-form surfaces. the polynomial series, Zernike series or cubic spline interpolation are used to describe it, which is similar to the cumulative approximation of several small areas on the surface. This is also a limiting concept when writing a program, every point must be resolved.

Spherical surface processing: In simple terms, the surface to be processed is a hemispherical surface or a spherical arc surface, with regular surface features, when carrying out milling, polishing and other processes, adjusting the Grinding head or polishing surface is relatively easy and can. maintain a good fit. The degree of adjustment and processing difficulty are relatively low.

Cylindrical processing: A cylindrical mirror is a common type of aspherical lens. Its intersection with the meridional and sagittal sections is the intersection of two arcs and two parallel straight lines, respectively, if the imaging properties of the two sections are measured respectively using the spherical system. Description, one section has optical power, while the other section has no optical power When a parallel laser beam passes through the cylindrical mirror, the focus can be stretched into a line in one direction. This part of the cylindrical mirror has its specific characteristics. uses in certain specific situations. For example, it has a wide range of applications in linear detector illumination, barcode reading, holographic illumination, optical information processing, computers, laser emission, laser systems powerful synchrotron radiation beamlines.

Technical indicators:

Processing diameter: mainly for processing aspherical surfaces. Aspherical surfaces cannot be measured by the radius of a sphere or cylinder, so the diameter of the processed surface is directly used for analysis, generally ranging from mm to m. The larger the processing diameter, the larger the size of the processing surface. While ensuring certain precision requirements, the requirements for large grinding head or high-efficiency ion beam are higher. The larger the diameter, the precision remains unchanged and the processing efficiency is low; the larger the diameter, the processing efficiency is constant and the precision is low. How to ensure high efficiency and high precision in the face of large diameter or large diameter processing is an important trend and direction in optical processing.

Surface precision:

PV: Peak to Valley, PV=Wmax-Wmin. In simple terms, it is the height difference between the highest point and the lowest point of the surface to be treated (usually in µm). There are subtle differences for spherical surfaces and planar surfaces. and aspherical surfaces. Define the difference. Due to the different spatial resolutions of detectors currently used in interferometer test equipment, noise, bright spots, etc. may occur. will have a relatively large impact, so the PV is sometimes larger than the actual data, so PVr is sometimes used to describe the shape of the surface. . Precision. Regardless of the PV or PVr value, the higher the value, the rougher the surface.

RMS: root mean square, root mean square, here is its calculation formula. The formula shows that it represents an average value of all concave and convex parts of the surface. If the PV value represents the maximum height difference over the entire surface, then the RMS represents the average of all height differences over the surface. The smaller the RMS, the flatter the surface shape. Therefore, it can be seen that the lower the PV value, the higher the accuracy of the surface shape. At the same time, the RMS value must be taken into account. It’s like a fluctuating point near the mean error line.

Surface Finish: Typically, two sets of numbers are used to represent the size of defects on the surface. For example, 40/20, 40 represents the size of limited scratches on the surface and 20 represents the size of pitting defects on the surface. The smaller the two values, the higher the surface finish requirements. (Aspect ratio >4:1 is striped and aspect ratio <4:1 is pitted).

Busbar Offset: This indicator is usually listed separately in the cylindrical treatment. The cylinder can be considered as a structure formed by a plane rotating around the busbar. Busbar offset refers to the offset of one side from the center of the plane in the direction of the cylinder axis. As shown below.

To summarize:

When it comes to technical indicators, the ideal is to reach the pinnacle for each indicator. But in practice, it is a process of compatibility and compromise. For example, when facing large diameter processing, if you want to improve a certain processing efficiency, you may lose part of the processing accuracy when you want to improve it; the overall processing accuracy, it is necessary to reduce the processing efficiency to a certain extent (higher processing accuracy requires longer iterative processing times and the higher the time cost). This type of indicator requires compromises.

There is also a type of indicators that emphasize one over the other. For example, the previously mentioned PV and RMS are not the best for a single indicator. Another indicator must be able to do this. The smaller the PV value, it does not mean. that the surface is better. To some extent, the proportion of RMS is greater.

Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.

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ISO 9001 Certificate

ISO 9001 is defined as the internationally recognized standard for Quality Management Systems (QMS). It is by far the most mature quality framework in the world. More than 1 million certificates were issued to organizations in 178 countries. ISO 9001 sets standards not only for the quality management system, but also for the overall management system. It helps organizations achieve success by improving customer satisfaction, employee motivation, and continuous improvement. * The ISO certificate is issued in the name of FS.com LIMITED and applied to all the products sold on FS website.

ISO 13485 certificate

ISO 13485 is an internationally recognized standard for Quality Management Systems (QMS) specifically tailored for the medical device industry. It outlines the requirements for organizations involved in the design, development, production, installation, and servicing of medical devices, ensuring they consistently meet regulatory requirements and customer needs. Essentially, it's a framework for medical device companies to build and maintain robust QMS processes, ultimately enhancing patient safety and device quality.

ISO 27001 certificate

ISO/IEC 27001 is an international standard for managing and processing information security. This standard is jointly developed by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). It sets out requirements for establishing, implementing, maintaining, and continually improving an information security management system (ISMS). Ensuring the confidentiality, integrity, and availability of organizational information assets, obtaining an ISO 27001 certificate means that the enterprise has passed the audit conducted by a certification body, proving that its information security management system has met the requirements of the international standard.

IATF 16949 certificate

IATF 16949 is an internationally recognized Quality Management System (QMS) standard specifically for the automotive industry. It builds upon the foundation of ISO 9001 and adds specific requirements relevant to automotive production and service parts. The goal is to enhance quality, improve processes, and reduce variation and waste within the automotive supply chain.

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