Influence of the Machining Process on the Thrust Force and Mechanical Characteristics for the Direct Drive System

This paper investigates the effects of the machining process on the thrust force and mechanical characteristics for the direct drive feed system driven by the flat permanent magnet synchronous linear motor (PMSLM) in machine tools considering the electromechanical couplings. Firstly, the cutting force in the machining process is researched. Then, the analytical model of the direct drive feed system is established and analyzed. The electromechanical couplings between the mechanical system and servo system in the direct drive feed system are studied. Furthermore, the influences of the cutting force on different couplings are analyzed, and the thrust force characteristic is analytically represented. Finally, the validity of the theoretical analysis is verified by the experiments, and the effects of the machining process on the dynamic precision of the feed system are discussed. The results show that the electromechanical couplings in the direct drive system will aggravate the effects of the machining process on the thrust force and mechanical characteristics of the feed system. A large number of new paired thrust harmonics will be produced. The influence of the machining process on the mechanical system will be extended from the discrete frequency point caused by the cutting force to the approximate frequency band caused by the thrust force, affecting the dynamic precision of the feed system and the cutting stability of the machine tool.