Research on Thermo-Mechanical Coupling Deformation for the Ball Screw of Machine Tool Spindle Feed System

Abstract

A spindle feed system is continuously subjected to cutting forces, cutting heat and frictional heat during machining processes, which interact to form a complex, nonlinear and thermal-force coupling field. The coupling field causes deformations and vibrations of the mechanism that affect the machining accuracy. Therefore, determining the thermal-force coupling dynamic characteristics of the mechanism is beneficial, as it lays the theoretical foundations for accurate error compensation and the design and optimization of the spindle feed system. The deformation of the spindle feed system in actual working processes is approached by modeling, simulation and verification. Based on the theory of mechanics and heat transfer, the models for the transient milling force and the temperature field are established to obtain the real-time, dynamic cutting force and the associated heat values. A thermo-mechanical coupling model is also deduced, and the deformations generated by the cutting force and heat are simulated using the finite element method. Moreover, the thermo-mechanical coupling deformations of the system are emulated. The above deformation results are tested and confirmed. This paper establishes the deformation rules under the cutting force and cutting heat as well as their associated coupling effects. When studying thermo-mechanical coupling, the initial deformations of the ball screw are dominated by the cutting forces. The effects of heat on the X-direction deformations gradually exceed the effects of the cutting forces. The Y-direction deformations are primarily caused by the forces, with little influence from the heat. The Z-direction deformations are mainly caused by the heat, with negligible influence from the forces.