Study of High Accuracy of Machine Tool with Bang-Bang Control

Application of bang-bang control to reduce the servo error generated by nonlinear elements in numerically controlled machine tools is presented in this paper. It has been prooved that the modified inverse transfer function control can eliminate the servo error of numerically controlled machine tools with linear elements but not the servo error with linear elements. The latter servo error can be reduced by the bang-bang control of compensating current for driving motor at start and direction change of the motion. As a result, by providing the machining centers with the control system, the geometrical accuracy of the workpiece at the quadrant corner is reduced from 27μm to 14μm and that at steep and gentle slope cutting is reduced from 27 μm to 7μm when cutting die weighing 98kN at the feed rate 10m/min.