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.