Mixed lubrication analysis in finite tooth contact surface of filtering reducer

The numerical analysis model for mixed lubrication of filtering reducer tooth was built considering the tooth contact geometry, normal load of meshing point, tooth parameters, real surface roughness, rheological behavior of lubricant. A completely numerical solution of mixed lubrication analysis in tooth contact surface was achieved by solving the Reynolds equations and elastic deformation equations using compound iteration method and fast Fourier transformation (FFT) method respectively. The pressure and average film thickness were obtained at engaging-in point, engaging-out point and pitch point of filtering reducer, and the effects of speed on the average film thickness and contact area ratio in tooth contact surface were also obtained. The results show that the pressure distribution along the tooth width direction is not equal at engaging-in point, engaging-out point and pitch point, and pressures on both sides are higher; the variation of pressure is smaller on both sides and the average film thickness is greater at engaging-in point. When the tooth contact surface is rough, with the decrease of speed of filtering reducer, the average film thickness at engaging-in point, engaging-out point and pitch point is decreased, and the contact area ratio increases, leading to poor lubrication. Besides, the average film thickness of meshing points of rough tooth contact surface is less than that of smooth tooth contact surface under the same conditions.