高速滚珠丝杠副的空心螺母热特性分析

The Thermal Characteristic Analysis on Hollow Nut of the High-Speed Ball Screw Pair

机床在高速运转时,由滚珠丝杠副的摩擦热引起的热变形对伺服进给系统的定位精度有很大的影响。滚珠丝杠副在整个运行过程中,摩擦热传递到螺母的热量最多,使得螺母温度上升并产生热膨胀,从而增大了滚珠丝杠副的预紧力,增大了摩擦热,使得滚珠丝杠副热量无法得到有效的控制,进而无法有效的控制热变形。通过将滚珠丝杠副螺母加工成空心,并通入冷却介质,达到了冷却螺母的目的。利用CFX软件,将理论计算得到的摩擦热加载到螺母滚道内,对不同冷却介质、不同载荷、不同转速下螺母的冷却效果进行分析,并对同一冷却介质不同流速下的流场和温度场进行分析。结果表明:运用专用冷却油的冷却效果最好;载荷及转速对空心螺母温升影响较小;揭示了空心螺母随着速度变化的流场变化规律以及温度场分布情况。

In a high speed operation,the positioning accuracy of the servo feed system of machine tool is seriously influenced by the thermal deformations which are caused by the friction heat of ball screw pair. During the operation,the friction heat transfers to the nut most,which makes temperature rising and thermal expansion,and then the preload is increased,and friction heat is increased next,so the heat cant be controlled effectively,so as the thermal deformations. Hollownut can break the bottleneck. Using CFX which is a Computational Fluid Dynamics（ CFD） software,the friction heat which was calculated by theoretical method was loaded on the ball screw race. By analysis on cooling mediums,it showed the special cooling oil had the best cooling effect; by analysis on the temperature rising under different loads and rotation rates,it showed the hollow nut had little influence on them; by analysis on the flow field and the temperature field under different flow velocity of cooling medium,it revealed the changing rule and the distribution of temperature.