A Study on Precision Thread Grinding with Numerically Controlled Compensation

Abstract

For leadscrews used on machine tools or length measuring instruments, requirement of grinding after hardening is increasing. Therefore, ground leadscrews of a higher pitch accuracy are required. Taking into account that one of the causes of pitch error in thread grinding is thermal deformation in the workpiece screw and the grinding machine, it is desirable that the pitch error compensation be performed according to the grinding condition of the workpiece screw. The purpose of this study is to improve the pitch accuracy of ground leadscrews by using the compensation of a numerical control system. The method is as follows : Initially thread grinding without compensation is performed. On the basis of the pitch error obtained in this case, a tape for compensation is punched, and a second thread grinding is performed with the operation of the numerically controlled compensation device. As the result of an experiment, in a ground leadscrew of 1m in thread length the accumulated pitch error in the whole length was reduced to about 5 μ by using this device.