CNC Knowledge: How to fundamentally resolve the damage, wear and collapse of the knife …

1. The demonstration of knife damage

1) Cut the blade at least

When the organization of the materials of the room, the hardness and the inequality of the balance, the wide angle of the front means that the resistance to the cutting blade is low, the rigidity of the artisanal system produces vibrations or a cut disconnected , when the shredding quality of the blade is not good, cutting the blade is subject to contrast. After that, the tool will lose part of the cutting capacity, but it can continue to work. By cutting continuous, the part of the damage to the blade area can develop rapidly, resulting in greater damage.

2) The cutting blade or the tip of the knife collapse

This damage method is often produced in a worse cutting condition that the micro-controller of the cutting blade, or the subsequent development of the micro-sex. The size and the beach of the broken accident are greater than the contrast of the contrast, which means that the tool completely loses the cutting capacity and must end the work. The tip of the knife is often called the tip.

3) Break the blade or tools

When the cutting conditions are extremely hard, the quantity of cut is too large, there are impact loads and the blade or the material of the tool is slightly cracked. The operation is caused by accidental. Once this damage form, the tool cannot continue to be used, which leads to a piece.

4) Plunging the surface layer of the blade

For materials with great fragility, such as hard alloy, ceramic, PCBN, etc. With a high content of ICT, due to potential defects or cracks in the surface tissue, or due to welding and grinding blades, there is a residual constraint on the surface layer. During the cutting process when it is not stable enough or the knife surface is tolerated, the surface layer is easily taken off when sex is affected. The peel can occur on the surface of the front knife and the knife can occur on the surface of the rear knife. The possibility of peeling the coating tool is more likely. The blade is slightly stripped and rear, and it can continue to work.

5) Plastic variant of the cutting site

Due to the low resistance of steel and high -speed steel, plastic variables can occur in its cutting site due to the low resistance. When the hard alloys operate directly at high temperature and in the three -way compression state, the surface layer is also generated, and even the plastic deformation surface of the cutting blade or the tip of the damage causes the collapse. The collapse generally occurs in the case of a large cutting dose and difficult treatment. The elastic module of the hard -based hard -based alloy is lower than the hard -based hard alloy. PCD and PCBN essentially have no plastic deformation.

6) The blade heat cracks

When the load of the tool and the thermal load which are affected by the transformation, the surface of the surface of the cutting part is inevitable to cause the thermal constraint of the cross due to the thermal expansion and the repeated contraction , which will cause fatigue and crack of the blade. For example, when the hard alloy millingr in hard alloy is dying to a high speed grinding, the blade tooth is constantly impacted and thermal constraint, and combed cracks are produced on the surface of the front knife. Although some tools do not have alternating loads and cross -transition constraints, due to the inconsistent temperature of the surface and the interior layers, the thermal stress will also be generated. cause cracks. When the crack is formed, the knife can continue to operate for a while.

Second, the wear of the knife

1. The cause of wear can be divided into:

1) Fruits

In the treatment material, there are often tiny particles with high hardness, which can draw grooves on the surface of the tool. Abrasive wear and tear exists in each surface and the surface of the front knife is the most obvious. In addition, the wear and tear of hemp can occur at different cutting speeds, but when the cutting temperature is low during the low speed cut, the wear produced in other reasons is not obvious, so the Abrasive wear and tear is the main reason. The lower the hardness of the tool, the more serious the grinding.

2) Cold welding wear

During the cut, there is a lot of pressure and strong friction between the room, the cut and the front and rear knives, so the cold welding will occur. Due to the relative exercise between friction, cold welding will be broken by a part, causing welding wear to cold. Cold welding wear is generally serious at an average cutting speed. Depending on experiences, crunchy metals are stronger than the anti-flash welding capacity of plastic metals; Welding trends. Cold welding is serious when steel at high speed and hard alloys are cut at low speed.

3) Disclosure and wear

During the contact of the cutting and tools at high temperature, the chemical elements on both sides are propagated in the solid, modifying the structure of the components of the tool, which makes the surface layer of the fragile tool and exacerbating the wear of the tool. The diffusion phenomenon still maintains the continuous diffusion of objects with a high depth gradient to low -gradient objects. For example, at 800 ° C, cobalt quickly spreads to dandruff and parts. At the time, the carbon atom in PCD will be transferred to the surface of the room to form a new alloy with a great intensity of diffusion, and the surface of the knife is graphicized. The dissemination of cobalt and tungsten is serious and the anti-division capacity of the titanium, 钽 and 铌 is strong. Consequently, the hard alloy of the YT class has better resistance to abrasion. When ceramics and PCBNs are cut, when the temperature is as high as 1000 ° C-1300 ° C, diffusion and wear are not significant. Due to the same materials, the part, the dandruff and the tools will generate thermal power in the contact zone during the cutting zone. This diffusion and wear under the action of thermal potential are called “thermoelectric wear”.

4) Oxidation wear

When the temperature increases, the wear of a softer oxide on the surface of the tool is formed by the softer oxide and the friction of the dandruff. Such as: oxidation reactions such as cobalt, carbides, titanium carbide and titanium carbide in 700 ° C at 800 ° C and hard alloys, and a milder oxides are formed;

2. It can be divided into:

1) Before the facial loss of the knife

When cutting plastic materials at high speed, the part of the cutting force is close to the cutting force, and under the action of the crumbs, it will carry a concave crescent, it is therefore also known as the time of the depression of the croissant. At the start of wear and tear, the front angle of the tool increased, which improved cutting conditions and facilitated the crumbs of the roller. When cutting crisp materials or cutting plastic materials at a lower cutting speed and thin cutting thickness, depression of the croissant is generally not produced.

2) The tip of the knife

The tip of the knife is the wear of the surface of the rear knife of the tip of the knife and the wear on the surface of the rear knife of the neighboring editor. Because the conditions for heat dissipation are poor and the concentration of stress is concentrated, the wear speed is faster than the surface of the rear knife. . They are mainly caused by the hardening layer and the cutting lines of the transformed surface. When cutting and hardening, it is very likely to cause gap wear. The wear point wear has the greatest impact on the roughness and precision of the treatment of the room.

3) The surface of the rear backstage

When a large cutting thickness and a cutting plastic cut, due to the existence of dandruff, the surface of the rear knife of the tool may not contact the part. In addition, the surface of the rear knife generally contacts the part, and a wear strip with 0 rear angles on the surface of the rear knife is formed. Generally, in the middle of the working length of the cutting blade, the surface of the rear knife is evenly carried uniformly. . Since various types of tools are almost all in cutting conditions, the wear and tear of the knife surface, in particular the crisp cut material or a smaller cutting thickness of the cutting plastic material. tool wear. The larger the VB, not only will the cutting force increase, will cause cutting vibrations, but will also affect the wear of the tip of the knife, which will affect the treatment accuracy and the quality of the treatment surface.

3. How to avoid damaging the tool

1) For the characteristics of materials and treatment parts, the different types and brands of the material to the tool are reasonably selected. Under the premise of having a certain resistance to hardness and abrasion, it is necessary to ensure that the material of the tool must have the necessary tenacity;

2) Reasonably select the geometric parameters of the tool. By adjusting the angle of the front and rear angles, the main partial corner, the inclusion angle of the blade, etc.;

Make sure the cutting blade and the tip of the knife have a good strength. Rating a negative edge on the cutting blade is an effective measure to prevent collapse;

3) Ensure the quality of welding and grinding blades and avoid various defects caused by welding and blade. The tools used in key processes must be crushed to improve the quality of the surface and check if there are cracks;

4) Reasonably select the quantity of cut to avoid excessive cutting force and a cutting temperature too high to prevent the knife from being damaged;

5) As much as possible to ensure that the craft system has good rigidity and reduce vibrations;

6) Take the correct operating method and try to make the knife unbearable or less to withstand the transfer load.

Third, the cause and countermeasures of the knife accident

1) Choose correct and specifications of the blade, inappropriate specifications,For example, the blade is too thin or too hard and crisp.

Countermeasures: Increase the thickness of the blade or install the blade and choose a brand with resistance and tenacity with high flexion.

2) Bad selection of geometric parameters (such as excessive front and rear corners, etc.)

Breeks: You can reset the knife from the following aspects.

① Reduce the front and rear corners correctly.

② Use greater inclination of negative blade.

③ Reduce the main partial angle.

④ Use a larger negative edge arc or blade mouth.

⑤ Repair the transitional cutting blade to improve the tip of the knife.

3) The blade welding process is incorrect,Causes excessive welding stress or welding cracks.

Counter-measuring:

① Avoid the structure of the three -sided knife groove.

② Correcting welded.

③ Avoid using oxygen flames heating and heat storage after welding to remove internal stress.

④ Use the structure of the mechanical clip as much as possible

4) Method of crushing with an incorrect bladeCausing crushing and grinding cracks;

Counter-measuring:

① Use intermittent grinding or diamond sand wheel.

② Use a softer sand wheel and cut often and keep the wheel of sharp sand.

③ Pay attention to the quality of the blade grinding and strictly control the amount of vibration of the strawberry tooth.

5) The selection of the cutting dose is unreasonableIf the quantity is too large, the machine tool is stifling; Little; At the time, the flow was too small.

Connection: re-sequence the quantity of cut.

6) The reasons for the structural reasons such as the underlying surface of the groove of the mechanical tightening knife knife or the blade blade.

Counter-measuring:

① Repair the bottom of the knife groove.

② reasonably arrange the position of the cutting fluid nozzle.

③ The hard bedtime pole adds hard alloy pads under the blade.

7) Excessive wear of tools.

Conversely: Change the knife or replace the cutting blade over time.

8) Insufficient cutting of the cutting fluid or the incorrect injection methodCaused sudden heat and cracking.

Counter-measuring:

① Increase the cutting of the cutting fluid.

② reasonably arrange the position of the cutting fluid nozzle.

③ Use effective cooling methods such as spraying cooling to improve the cooling effect.

④ Use * Cut to reduce the impact on the blade.

9) Installation of incorrect toolsFor example, the installation of the car tool is too high or too low;

Conversely: reinstall the tool.

10) The rigidity of the process system is too poorCauses too much cut.

Counter-measuring:

① Increase the auxiliary support for the part and improve the rigidity of the workers.

② Reduce the extension length of the tool.

③ correctly reduce the rear corner of the tool.

④ Adopt other vibration measures.

11) Meticulous operationFor example, when the tool is cut in the middle of the room, the action is too fierce;

Counter-measuring: pay attention to the operating method.

Fourth, dandruff tumor

1) Reasons for training

In the part of the cutting blade, in the contact area of ​​the knife liner, due to the high pressure, the lower metal of the crumbs is integrated into the peak of micro-one descents on the surface of the front knife, forming A real metallic contact without space, which generates adhesion. In the link area, a thin layer of a layer of metal material will be blocked on the surface of the front knife with the lower layer of the dandruff. With the continuous flow of crumbs, under the thrust of the flow of the successor cut, the stagnant accumulation material and the upper layer of the dandruff were relatively slippery and on the left, becoming the foundation of film tumors. Subsequently, the second layer of stagnation cutting materials will be formed on it, so that the accumulation of stratigraphy constantly forms a film tumor.

2) Characteristics and effects on cutting treatment

① The hardness is 1.5 ~ 2.0 times higher than the material of the material.

② The work corner of the knife after the formation of dandruff tumors increased significantly, which played a positive role in reducing the film deformation and the reduction of the cutting force.

③ Since the flea tumor protrudes from the cutting blade, the actual cutting depth is increased, which affects the size and precision of the room.

④ The dedicating tumors will cause the phenomenon of “plow ditch” on the surface of the room, affecting the roughness of the surface of the room. ⑤ The fragments of the dandruff tumors will be binded or will integrate the surface of the room to cause hard points, affecting the quality of the treated surface of the room.

According to the above analysis, we can see that the chip tumors are particularly unfavorable for cutting and treatment.

3) Control measures

Do not make the lower layer of the dandruff and do not strengthen or deformation of the front knife surface, the following measurements can be avoided by the occurrence of dandruff tumors.

① Reduce the roughness of the surface of the front knife.

② Increase the front area of ​​the tool.

③ Reduce the cutting thickness.

④ Use a low speed cut or a high speed cut to avoid the cutting speed that is easy to form with dandruff tumors.

⑤ The appropriate heat treatment of room materials improves its hardness and reduces plasticity.

⑥ Cut the liquid with good anti-adhesion (such as the fleece fluid containing chlorine containing chlorine).