Treatment of threads is one of the very important applications of CNC machining centers.
With the improvement of the performance of the CNC machining center and improving cutting tools, thread processing methods are also improving and the accuracy and efficiency of the treatment of thread also improve gradually. In order to allow craftsmen to reasonably choose methods of treatment of threads in treatment, improve production efficiency and avoid quality accidents, several methods of treatment of ordinary threads used in machining centers CNC will be summarized as follows:
CNC technology | Several methods of treatment of common threads in CNC machining centers
1. TAP treatment method
1.1 Classification and characteristics of TAP treatment
The most commonly used treatment method is the use of taps to treat threaded holes.
In the 1980s, threaded holes were subjected to flexible tapping methods, that is to say that flexible tapping children were used to tighten the tapping chuck. Synchronization outside the synchronization of the axial power supply of the machine and the speed of the spindle. Flexible tapping mandrel has a complex structure, high cost, damage to damage and low treatment efficiency. In recent years, the performance of CNC machining centers have gradually improved and the rigid tapping function has become the basic configuration of CNC machining centers.
Therefore, rigid tapping has become the main method of treatment of threads today.
That is to say that the tap is tight of a rigid spring mandrel, and the spindle power supply and the speed of the spindle are controlled by the machine tool.
Compared to flexible tapping children, spring deadlines have a simple structure, cheap prices and a wide range of uses. At the same time, rigid tapping can be used to make a high -speed reduction, improve the efficiency of machining centers and reduce manufacturing costs.
1.2 Determination of the threaded bottom hole before typing
Treatment of thread bottom holes has a large impact on the lifespan of the tap and the quality of the treatment of the wire. Generally, the diameter of the drill lower hole drill is close to the upper limit of the tolerance of the diameter of the threaded bottom hole.
For example, the diameter of the lower hole of the m8 threaded hole is ф6.7 + 0.27 mm, and the diameter of the drilling bit is 6.9 mm. In this way, the TAP treatment allowance can be reduced, the load on the tap can be reduced and the lifespan of the tap can be improved.
1.3 Selection of taps
When selecting a tap, the corresponding tail must be selected according to the processed material.
Because the valves are very sensitive to the material to be treated compared to the strawberries and boring cutters. For example, the use of cast iron taps to treat aluminum parts can easily cause the drop in threads, random loops or even a break, which causes a boost. Second, attention must be given the difference between the tap through and the blind tap. The front end of the blind hole has a short guidance and the elimination of fleas is the withdrawal of the rear chips. The use of taps through to treat blind holes cannot guarantee the depth of treatment of the thread. In addition, if a flexible tapping child is used, you should also pay attention to the diameter of the handle of the tap and the width of the four sides, which must be the same as the chuck of the tap; Be the same as the diameter of the spring jacket. In short, it is only by choosing taps that smooth progress of treatment can be ensured.
1.4 CNC Programming for tap treatment
The programming of TAP treatment is relatively simple. Now, the machining center generally solidifies the tapping sub-program, simply attribute values to each parameter. But it should be noted that different CNC systems and sub-programs formats are different and that the meaning of certain parameter representations is different.
For example, the Siemen840C control system has a programming format: G84 X_Y_R2_ R3_R4_R5_R6_R7_R8_R9_R10_R13_. During programming, simply assign these 12 parameters.
2.
2.1 Characteristics of thread grinding
Thread grinding uses threadwriting tools, the link to three machining areas, namely the arc interpolation of the X and Y axis, and the linear power supply method is used to treat threads.
Thread grinding is mainly used for the treatment of large holes and threaded holes of difficult to machine materials. It has the following main characteristics:
⑴ Rapid treatment speed, high efficiency and high treatment of treatment. The tool material is generally carbide material and the tool speed is fast. The tool has a high manufacturing precision, so that the precision of the thread striker is high.
⑵ The milling tools have a wide range of applications. As long as the height is the same, a tool can be used, whether it is a wire on the left or a right wire, which is conducive to reducing the cost of the tool.
⑶ Treatment of grinding is easy to remove fleas and cool, and the cutting situation is better than taps. For the treatment of the wire of large parts and precious parts.
⑷ Because there is no frontal guidance of tools, it is suitable for the treatment of blind holes with holes and short thread holes without withdrawal.
2.2 Classification of threading milling tools
Threads milling tools can be divided into two types, one is a carbide insert staple with a machine blade, and the other is a built -in coatage strawberry. The machine-clip tool has a wide range of applications. Integrated carbide milling cutters are generally used to treat holes with thread depths lower than the length of the tool.
2.3 CNC programming of crushing threads
The programming of threading tools is different from that of other tools. The following points must be ready to prepare:
⑴ First of all, the threaded bottom hole must be well treated and the small diameter holes must be treated with forests, and the larger holes must be bored to ensure the precision of the threaded bottom hole.
⑵ When cutting the tool, the arc track must be used, usually half the turn to cut or go out. thread. The compensation value of the radius of the tool must be provided for the moment.
⑶ When the arcs of the X axis and Y are interpolated for a week, the main tree must travel a thread step along the direction of the Z axis, otherwise, it will make the wire complete at random.
⑷ Specific example Program: The diameter of the thread molding cutter is φ16, the threaded hole is M48 × 1.5 and the depth of the threaded hole is 14.
The processing procedure is as follows:
(The threaded lower hole procedure is omitted, the bottom hole should be bored for this hole)
G0 G90 G54 X0 Y0
G0 Z10 M3 S1400 M8
G0 Z-4.75 Entrance into the deepest part of the wire
G01 G41 x-16 Y0 F2000 move to the power position and add the radius compensation
G03 X24 Y0 Z-14 I20 J0 F500 Use 1/2 Circle Arc Cut during the cut
G03 X24 Y0 Z0 I-24 J0 F400 Cut the entire wire
G03 x-16 Y0 Z0.75 I-20 J0 F500 Cut with 1/2 Circle Arc when you cut G01 G40 X0 Y0 Return to the center, Cancel the compensation for the department
G0 Z100
M30
3. Traction method
3.1 Characteristics of the loop method
Large threaded holes can sometimes be encountered on the parts of the box.
Install a thread filming tool on the disturbance toolbar to bother the wire.
The company treated once a batch of parts with the M52x1.5 wire and the degree of position is 0.1 mm (see Figure 1). Because the degree of position requirements are high and the wire hole is large, it is impossible to use taps for treatment, and there is no thread.
3.2 Things to note when selecting and the loop method
⑴ After starting the pin, there should be a delay to ensure that the spindle reaches the nominal speed.
⑵ When the tool is retraced, if it is a threaded hand cut by hand, because the tool cannot be sharpened symmetrically, it cannot be retracted.
⑶ The manufacture of the tool stem must be precise, in particular the position of the groove of the tool must be consistent. If it is incoherent, the treatment of multiple tools cannot be used. Otherwise, this will cause random deductions.
⑷ Even if it is a very thin loop, it cannot be picked with a knife during the loop, otherwise it will cause a loss of tooth and poor roughness of the surface, therefore at least two knives must be divided in two.
⑸ The treatment efficiency is low and is only suitable for small lots of single parts, special height wires and no corresponding tools.
3.3 Specific examples procedures
N5 G90 G54 G0 X0 Y0
N10 Z15
N15 S100 M3 M8
N20 G04 X5 Distage, so that the spindle reaches nominal speed
N25 G33 Z-50 K1.5
Orientation of pin N30 M19
N35 G0 X-2 Give the knife
N40 G0 Z15 Delay
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