The worms processed on CNC lathes generally have a larger pitch. Due to their tooth shape, the blade and the workpiece have a large contact surface. It is easy to damage the cutting tool due to the extrusion of iron chips between the workpiece and the tool during processing. Although the operator can use a tool with an elastic arbor and feed at a very small cutting depth, the above problems cannot be fundamentally solved.
The same difficulty is faced when machining worms on CNC lathes. The CNC lathe will not stop automatically because the tool collapses, so this problem is even more difficult to solve. The manually operated horizontal ordinary lathe can be flexibly grasped by the operator according to the cutting situation, and even the tool is withdrawn halfway through the processing, so as to avoid worse situations.
The following is a method that uses the lathe machining method of CNC lathes and its precise positioning performance, and adopts the method of “connecting points to form a line” to synthesize the two side lines of the trapezoid, so as to effectively solve this problem.
The cutter can be made of cemented carbide. This cutting method is to change one cut to three cuts, thereby reducing the cutting resistance. This method is actually the use of the left and right cutting method. The author changed it to “center, left, and right” cutting, because if you don’t cut a knife from the middle first, the iron chips will still squeeze the knife, which is derived from the actual in conclusion. Unlike the left-right cutting method of non-CNC lathes, “center, left, and right” cutting on a CNC lathe requires accurate calculations. This calculation takes a little time, but it exchanges for improvements in processing efficiency and peace of mind during work. The cutting speed can be selected from 70 to 90m / min, and the cutting depth ap = 0.1 to 0.15mm (depending on the performance of the machine tool, whether it is suitable depends on the thickness and color of the iron filings).
The following describes the coordinate calculation method:
cot = 20 ° = 1: 0.364, when the X direction feeds 0.1mm, the Z direction changes by 0.0364mm from the previous knife. This 0.0364mm is in the left and right direction, that is, eat a knife from the middle, and then compare the left and right respectively The Z direction decreases and increases by 0.0364mm, and the values shown in the following table can be listed first for the convenience of programming.
x 50 49.8 49.6 49.4 49.2 49
W 1.46 1.42 1.39 1.35 1.31 1.28
Eating left and right on the CNC is actually changing the Z coordinate of the starting point when turning the thread. This must be kept in mind. The thread command is G92, the Z-direction zero position at the end face of the workpiece, and the thread pitch is 8 mm.
If you press “Middle, Left, Right” for many times, the cutting is easy and the chip removal is smooth. The purpose of “joining points into lines” has been achieved, turning the limitations of CNC into special features. If the coolant is added to wash the iron chips during cutting, the effect will be better.