A Study on Precision Thread Grinding : Causes of drunkenness of a leadscrew in thread grinding

Abstract

Usually leadscrews used for machine tools or length measuring machines need to be ground. But in thread grinding, the cumulative pitch error and the drunkenness of the thread, which have bad effects on the feed accuracy of these machine tools or measuring machines, take place from many causes, such as geometrical errors, thermal deformations of the ground workpiece screw and the thread grinding machine, mechanical accuracy of the latter and so on. In this paper, the drunkenness of the leadscrew is discussed, especially; its causes are pointed out and each influence of them is estimated by measurement. The results show that the table feed error of the thread grinding machine, which is generated by the rotational angle transmission error at the change gear train, the going in-and-out in the axial direction of the leadscrew engaged with the nut, and the rotation with whirling of the main spindle center, mainly accounts for the drunkenness of the thread ground in practice.