Machining, Measurement, and Control Laboratory

A Study on Improvement of Circularity by Optimizing Tool Path of Boring
Yasuhiko Suzuki, Atsushi Matsubara, Yoshiaki Kakino

This paper deals with controlling approaching and escaping paths for the fixed circular machining pattern on NC machine tools. Recently accuracy of circular motion on NC machine tools has extremely improved. One of the reasons is that servo control gain became higher. Several servo errors caused by motor cogging or guide friction were reduced. The other reason is that the KGM measurement system has been developed in addition to the DBB. Different radius circles became able to be tested. However, there are two errors that do not appear on circularity measurement with the DBB or the KGM. The first one is servo error due to different acceleration between approaching path and shaping path in circular machining pattern. The error cannot be observed because circularity measurement pattern is different from circular machining pattern. The second one is tool deformation due to cutting force. Circularity measurement is done without cutting, so the measurement cannot observe the error. In this study, the errors are analyzed and a new path pattern is proposed to reduce the errors.