Modeling and analysis of thermal-dynamic coupling of sliding guide of CNC machine tools considering nonlinear characteristics

Abstract

The thermal and dynamic characteristics of the sliding guide system in CNC machine tools are critical factors influencing machining accuracy and operational stability. Nevertheless, conventional thermal or dynamic analyses in isolation are insufficient to elucidate the influence of thermal-dynamic coupling on the overall performance of the system. In this paper, based on the thermal-dynamic interaction mechanism, a thermal-dynamic coupling model of the sliding guide system is constructed. First, a multi-node thermal network model is established by accounting for the effects of bonding surface geometry and micro-morphology on contact force, thermal resistance, and heat generation. Then, a multi-degree-of-freedom nonlinear dynamic model of the sliding guide system, which takes into account the effects of thermal deformation, micro-morphology and friction of the bonding surface, frictional moments of the bearing and the nut, and the actual torque of the motor, is developed by using the concentrated mass method in order to evaluate the transient dynamic behavior. Next, the mechanism and effects of the coupling between the thermal network model and the dynamic model of the sliding guide system are analyzed in depth, which involves the interactions between thermal expansion, frictional heat generation, structural deformation and the contact forces of the moving parts. Finally, a closed-loop iterative algorithm is proposed to solve the coupled model. The accuracy and validity of the coupled model are experimentally verified. The results of the study show that there is a non-negligible interaction between the thermal and dynamic effects of the sliding guide system. The accuracy of the thermal network model considering the coupling effect is higher than the accuracy without considering the coupling effect. The coupled model is able to effectively predict the thermal behavior and dynamic properties of the system.