A study on Precision Screw Cutting by Using Feedback Control

In conventional precision screw cutting, the pitch accuracy of cut screw mainly depends on the lead screw of the screw cutting lathe. The lead screw serves as the accurate feeder of a cutting tool, on the other hand it is worn out by the heavy load of the carriage. Accordingly, the pitch accuracy of the lead screw will be degraded rapidly. While, by additional installing a precision master screw and a feedback controller besides the ordinary lead screw, the error caused by the driving screw will be eliminated and the high accuracy will be held for a long time. This paper is the report of the control effect in our screw cutting lathe, which is equipped with the control system based on the above mentioned principle. The screw cutting accuracy of our lathe being degraded to 80μ/300mm, was improved to 17μ/300mm by using the feedback controller, and further it attained to 4μ/300mm by using the compensation cam at the same time.