考虑动载荷和表面粗糙度的渐开线齿轮摩擦因数的研究

 进行齿面摩擦因数的研究，对于减少摩擦损失、改善系统传动性能等具有重要的意义．建立渐开线圆柱齿轮的非线性时变单自由度动力学模型，求解得到动态啮合力和单对轮齿的受力．结合载荷分担概念和弹流润滑理论，得到考虑表面粗糙度和动态载荷的不同啮合位置处的齿面摩擦因数，并与静态载荷条件的结果进行对比．同时分析转速、表面粗糙度和润滑剂黏度等工作条件对摩擦因数的影响．研究结果表明：动态载荷对油膜厚度、油膜承载比例和摩擦因数均有一定程度的影响．进入啮合段，油膜较薄，油膜承载比例较低.退出啮合段，油膜增厚，油膜承载比例增高.转速对摩擦因数的影响并非单调的，摩擦因数先是随着转速的增大显著减小，而后随着转速的增大而增大．随着表面粗糙度的增大，摩擦因数随之明显增大．在一定的黏度范围内，随着润滑剂黏度的增大，摩擦因数随之明显减小．

Friction coefficient analysis of involute spur gears with consideration of dynamic load and surface roughness

Study on the friction coefficient of the tooth surface plays an important role on reducing friction loss and improving the system transmission performance. A non-linear time-varying dynamic model of involute spur gear was established to obtain the dynamic mesh force and final instantaneous tooth force under dynamic conditions. Considering the surface roughness and dynamic load, the friction coefficient along line of action was obtained by employing the load sharing concept and elastohydrodynamic lubrication theory. Comparisons between the results from the steady and dynamic loading conditions were given. The effects of rotational speed, surface roughness and lubricant viscosity on the friction coefficient were also analyzed. The results showed that dynamic load would affect the oil film thickness, the oil film load scaling factor and the friction coefficient to some extent. The oil film seemed thinner at the beginning of meshing region and appeared thicker at the end of meshing region. Rotational speed didn't affect friction coefficient monotonically. As rotational speed increased, friction coefficient decreased evidently. Then with the decreasing of rotational speed, the friction coefficient became larger. The friction coefficient increased evidently when the surface roughness increased and the increase of lubricant viscosity in a certain range would lead to a smaller friction coefficient.