基于接触热阻的磨齿机电主轴热特性分析

大规格数控成形磨齿机高速电主轴系统在加工过程中产生大量热量,导致砂轮主轴产生相应热变形,影响加工精度。针对这一现象,提出了一种考虑接触热阻的瞬态热-结构耦合分析方法。该方法基于分形理论,利用W-M分形函数表征结合面接触状态,使用均方根测度法对分形参数进行识别。结合基体热阻和收缩热阻的影响计算结合面间总接触热阻,并计算热源发热量及各部件的对流换热系数,建立了综合考虑内部热源、边界条件和接触热阻的综合有限元模型,获得热误差仿真结果。分析电主轴温度及热变形在是否考虑接触热阻情况下变化差异。最后建立电主轴系统热误差测量试验平台,通过试验验证了该方法的准确性和可靠性。通过仿真得到温度及热位移量与实验值基本一致。

Thermal characteristic analysis for motorized spindle of gear grinding machine tools based on thermal contact resistance

The high speed motorized spindle system of large computer numerical control(CNC)gear grinding machine tools generates a large amount of heat during the processing,which causes the corresponding thermal deformation of the spindle and grinding wheel,affects the machining accuracy.To solve this problem,a transient thermal-structural coupled analysis method was proposed with thermal contact resistance(TCR)been taken into account.Based on the fractal theory,the W-M fractal function was used to characterize the contact state of the combined surface and the fractal parameter is identified using the root mean square measurement method,the total thermal contact resistance was calculated in combination with the bulk resistance and the constriction resistance.The heat of heat source and the convection heat transfer coefficient of each component were calculated,a comprehensive finite element model was established with consider internal heat source,boundary condition and thermal contact resistance.Thermal error simulation results were obtained.The variation of spindle temperature and thermal deformation was analyzed when thermal contact resistance was taken into consideration.Finally,the thermal error measurement platform of motorized spindle system was established,and the accuracy and reliability of the method were verified.Simulation results show that the temperature and thermal displacement were basically coincide with the experimental data.