Working methods of servo cam grinder and its accuracy compensation strategy

WU Xing 1， HUANG Wen-guang1， HUANG Xing-hong1， PAN Xu-hua2
（1. School of Mechanical Engineering， Zhejiang Institute of Mechanical & Electrical Engineering，
Hangzhou 310053，China；  2. Suzhou Yawei Precision Machine Tool Plant， Suzhou 215000， China）

Abstract： Aiming at the problems of decline in accuracy caused by the cam servo grinding workpiece speed difference， the servo system response deviation， the hardware manufacturing errors and repercussion factors of repeatability error etc.， the online measurement technology and Sinumerik 840D of interpolation table together with electronic gear function were applied in the machine motion control systems. After the analysis of the trajectory of the grinding process and control programs， a method of 360 pcs discrete error compensation value was posted through online measurement handling by the VB program embedded in the PCU system，automatically generated the specific processing procedures with interpolation table and electronic gear function by control method of the superimposing coaxial movement， the compensation value was superimposed to the feed axis. Finally， the cam machining NC programs with data of error compensation was updated according to the actual processing. The engineering prototype were tested. The test results show that the engine camshaft profile of maximum machining error is reduced to lower than 2.6 μm， the mechanical vibration and nonlinear friction disturbance are the main sources of residual error. The results show that the motion control and error compensation method can reduce the impact of the repeatability error factors on the workpiece accuracy.
Key words： camshaft；servo grinder；accuracy compensation；example program