Identification Method of Error Motions and Geometric Errors of a Rotary Axis by R-Test

While evaluating the accuracy of high-precision machine tools, it is critical to reduce the error factors contributing to the measured results as much as possible. This study aims to evaluate both the error motions and geometric errors of the rotary axis without considering the influence of motion error of the linear axis. In this study, only the rotary axis is moved considering two different settings of a reference sphere, and the linear axes are not moved. The motion accuracy of the rotary axis is measured using the R-test device, both the error motions and geometric errors of the rotary axis are identified from the measurement results. Moreover, the identified geometric errors are verified for correctness via measurement with an intentional angular error. The results clarify that the proposed method can identify the error motions and geometric errors of a rotary axis correctly. The method proposed in this study can thus be effective for evaluating the motion accuracy of the rotary axis and can contribute to further improvement of the accuracy of the rotary table.