A Study on the Motion Accuracy of NC Machine Tools (6th Report)

Generating mechanism of the stick motion, which occurs on the motion error during circular interpolation motion for NC machine tools, has been studied The motion errors including the stick motion were measured by Double Ball Bar test. Then simultaneously feedback values of the servo motor, the encoder, the linear scale were measured to compare the relationships between them, and the stick motion is generated due to the time lag at servo motor reversing, where lost motion is due to the elastic deformation of ball-screw driving system. A feed-forward control method was developed to compensate the stick motion error.