Development of a Measuring Method for Motion Accuracy of NC Machine Tools Using Links and Rotary Encoders (Modification to the Measuring System, Error Parameters Estimation and the Results of Measurement Experiments)

An instrument capable of measuring arbitrary dynamic NC tool paths in a three-dimensional space has been developed. In this paper, we describe the structure of the newly modified device and the estimation method for 11 error parameters concerning the link length errors and inclination of link axises. The estimated errors parameters have been applied to tool path trajectories which are calculated from rotary encoders output angles. The results show significant accuracy improvement. The fact that the measurement of a machine motion in rectangular tool path is possible with an accuracy of ±3 μm error and that the accuracy of circularity tests are much improved, show the validity of our proposed measurement device and that of the error parameters estimation method.