Simultaneous Measuring Method of Geometric Errors in Machine Table Motion

ABSTRACT The geometric error of table motion which consists of three translational and three angular errors affects the machining accuracy in machine tools. Hence it is required to measure these six errors precisely at the same time to evaluate the three–dimensional table motion. In this paper, a new method for the simultaneous measurement of these six errors is proposed. In this method, the positioning error is measured based on the conventional principle of laser interferometry. And other five errors are measured by using the geometric relations between three parallel laser beams, which are produced by dividing the laser beam for distance measurement, and three photo–diodes located on the measured table. The measurement of five errors except the positioning error, which can be measured precisely by the conventional principle, is carried out with a prototype measuring system. As the test results, it is confirmed that five errors can be measured simultaneously without any mutual interferences and that the method proposed here is valid.