基于接触热阻的高速精密电主轴热特性分析

主轴系统热问题是高精度机床必须要考虑的关键问题,接触热阻的大小影响机床的传热性能,从而影响其加工精度.利用表面接触的分形理论,计算接触面的量纲一的接触面积,针对接触微凸体的热阻由基体热阻和收缩热阻形成接触对,建立了一个考虑接触界面基体热阻和收缩热阻的表面接触热阻模型,讨论了不同的分形参数对接触热阻的影响.以立式加工中心电主轴系统为研究对象,分析了电机的损耗发热和轴承的摩擦发热,运用有限元软件对电主轴模型在有无接触热阻2种情况下的稳态温度场和稳态热变形进行仿真分析.讨论了有无热阻情况下电主轴温度和变形变化量,论证了接触热阻对电主轴热温度场和热变形的影响.结果表明:电主轴考虑接触电阻时温度将升高,变形将增加.

Analysis of High Speed Motorized Spindle Thermal Characteristics Based on Thermal Contact Resistance

The spindle system heat problem is a key problem that must be considered for high precision machine tool. The thermal contact resistance ( TCR) affects the heat transfer performance of a machine tool, which affects the machining accuracy. In this paper, a model considerating the bulk resistance and shrink resistance surface of TCR was established by using the fractal theory of the contact surface. Motor heat and bearing friction heat in a vertical machining center motorized spindle system were analyzed. In case of considering TCR and without considering TCR, steady state temperature field and the steady state thermal deformation were analyzed. Results demonstrate the importance of TCR to the problem thermal characteristics of motorized spindle. The temperature will be higher and the deformation will be serious when TCR is considered.