A DBB-Based Errors Mesurement Method For 3-Axis CNC Machine Tool

The measurement of the main errors of machine tool is the precondition for improving the accuracy of machine tool by compensation method. This paper research on the measurement for the main thermal errors of 3-axis machine tool with Double-Ball-Bar (DBB), such as spindle thermal drifts errors, the parallelism error between spindle and guide way of the Z-axis, the scaling mismatch errors and the cyclic errors of the ballscrew shaft.First, a volumetric error synthesis model was derived, which consists of both geometric errors and thermal errors.Then the model was applied to simulate the ball bar test in order to get the results of the machine tools at different time and different temperature. The spindle thermal drifts errors can be obtained by volumetric analysis at the static test mode of the DBB. And the other thermal errors can be obtained by simulating the circularity(semicircular)traces of the DBB test at the dynamic test mode.At last, we get the main geometric errors and the spindle thermal drifts errors by experiment.Obviously, the novel thermal errors measurement method based on the use of DBB is more efficient and effective compared to traditional measurement systerms.