Modeling and application of thermal contact resistance of ball screws

Abstract

Aiming at determining the thermal contact resistance of ball screws, a new analytical method combining the minimum excess principle with the MB fractal theory is proposed to estimate thermal contact resistance of ball screws considering microscopic fractal characteristics of contact surfaces. The minimum excess principle is employed for normal stress analysis. Moreover, the MB fractal theory is adopted for thermal contact resistance. The effectiveness of the proposed method is validated by self-designed experiment. The comparison between theoretical and experimental results demonstrates that thermal contact resistance of ball screws can be obtained by the proposed method. On this basis, effects of fractal parameters on thermal contact resistance of ball screws are discussed. Moreover, effects of the axial load on thermal contact resistance of ball screws are also analyzed. The conclusion can be drawn that the thermal contact resistance decreases along with the fractal dimension D increase and it increases along with the scale parameter G increase, and thermal contact resistance of ball screws is retained almost constant along with axial load increase before the preload of the right nut turns into zero in value. The application of the proposed method is also conducted and validated by the temperature measurement on a self-designed test bed.

摘要

为了求解滚珠丝杠副的接触热阻,提出了一种基于最小余能原理和MB 分形理论的解析方法。 该方法在求解接触热阻时可考虑接触面的微观分形特征。采用最小余能原理求解法向应力分布,进而 采用MB 分形理论求解接触热阻。通过自行设计实验验证了该方法的有效性。理论和实验的结果对比 说明,该方法可准确获得滚珠丝杠副接触热阻。在此基础上,讨论了分形参数对滚珠丝杠副接触热阻 的影响,分析了螺母轴向载荷对滚珠丝杠副的接触热阻的影响。结果表明,接触热阻随着分形参数D 的增加而减小,随着尺度参数G 的增加而增加。在右螺母预紧力变为零之前,滚珠丝杠副接触热阻随 着轴向载荷的增加几乎保持不变。最后,开展了该建模方法在自行设计试验台的应用,开展了相应的 温度测试,进一步验证了该方法的有效性。