Feasibility study of hybrid spindle system with ball and electromagnetic bearings for suppression of chatter vibrations during milling with a small end mill

摘要

In the end milling process, it is very important to prevent the occurrence of chatter vibrations because they can cause problems such as the reduction of tool life, tool fracture, and deterioration of the machined surface quality. The aim of this study was to theoretically investigate a hybrid spindle system with a ball bearing at one end and an electromagnetic bearing at the other for the suppression of chatter. The equation of state for the proposed spindle control system was derived under the assumptions that the silicon steel cylinder was subjected to an electromagnetic controlling force and the end mill was subjected an external force at its lower end. It was demonstrated that the stability limit for regenerative chatter with state feedback was approximately three times that without state feedback when the feedback coefficient was determined by the pole assignment of the control system under the assumption that the real part of the roots calculated from the characteristic equation for the system increased by three times.