CNC lathes have higher requirements for thread turning than ordinary turning operations. The diamond cutting force is generally higher, and the cutting end radius of the thread insert is smaller and weaker. In thread processing, the feed speed must correspond exactly to the pitch of the thread. For a pitch of 8 threads/inch, the tool must advance at a feed rate of 8 revolutions/inch or 0.125 inches/revolution. Compared with ordinary turning applications, the feed speed of thread turning is 10 times higher, and the force at the tip of the thread processing insert may be 100-1,000 times higher.
The radius of the end that bears this force is generally 0.015 inches, while the radius of the conventional turning diamond cutting insert is 0.032 inches for thread machining on a CNC lathe. For threading inserts, the radius is strictly limited by the root radius of the permitted thread shape. It is also limited by the required cutting action, because the material cannot withstand the shearing process in ordinary turning, otherwise thread deformation will occur.
The result of the higher cutting force and the narrower force concentration range is that the thread processing insert bears much higher stress than the general turning tool. Therefore, in CNC lathe processing, thread processing can be divided into “fastening thread” and “transmission thread”. Let’s discuss the method of CNC lathe processing thread:
1. Thread lathe processing method The commonly used cutting lathe processing methods of thread include threading, thread milling, thread grinding, thread tapping and threading, etc.; few cutting processing methods include thread rolling and thread rolling, etc.; special processing methods include electric discharge machining Conjugate synchronous rotation processing with EDM, etc.
2. Thread cutting principle. There must be a strict movement relationship between the spindle and the tool of the CNC lathe, that is, the tool moves evenly by a lead distance without the spindle rotates one cycle.
3. Machine tool adjustments When processing threads on CNC lathes, we have to do in advance for thread turning: adjust the spindle speed and adjust the pitch.
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