Modeling and analysis of thermal behavior of feed system based on full-state thermal contact resistance

The dual-drive feed system can significantly reduce the effects of nonlinear friction. However, due to the numerous heat sources in its system, the thermal responsive mechanism is still unclear. The reason restricts the realization of high-precision micro-feed. Moreover, the existing thermal simulated model of the machine tool oversimplifies the calculation process of thermal contact resistance (TCR), resulting in a significant error in simulation. Therefore, a full-state TCR calculation model is proposed, and based on the model, a high-precision thermal behavior model of the dual-drive feed system is established. Firstly, the entire deformation process of the asperities is characterized by using fractal theory, and the TCR between the joint parts of the feed system is calculated by considering the thermal resistance of air or grease. A thermal simulated model of the dual-drive feed system is developed based on the solved heat generation and the heat transfer coefficients. Then, the temperature rise characteristics of the dual-drive feed system and the responsive mechanism of thermal deformation under different working conditions are analyzed. The influence of TCR on temperature field distribution and deformation field is discussed. Finally, the experiments on temperature rise and thermal deformation are conducted on the dual-drive feed system. The results of the simulated analysis and experiments show that the accuracy of the simulation can be significantly improved by using the full-state TCR model. The error of the thermal model based on the full-state TCR is much smaller than that of the general TCR model and the without TCR. The accurate description of the TCR has an essential impact on the accuracy of the simulated model, and the obstruction of the heat flow by air or grease cannot be neglected.