Rolling-sliding characteristics of planetary roller screw considering elastic deformation

In order to disclose the rolling-sliding mechanism of the planetary roller screw, the models of rolling-sliding analysis of the planetary roller screw(PRS) with and without elastic deformation are developed by using the equivalent ball method based on the characteristic of spherical surface of the roller thread. The rolling-sliding characteristics are studied by calculating the relative slip velocities of contact points on the screw side and the nut side. The slide-roll ratios of two contact sides are calculated respectively to express the relative amounts of sliding and rolling. Furthermore, the influence of contact angle, helix angle and tooth number of the roller thread on slide-roll ratios is taken into account. The results show that the slide between the screw and the rollers always occurs considering elastic deformation and the relative slip velocity in the direction of tangent along helical trajectory on the screw side and the nut side is the highest. The influence trends of contact angle and helix angle on slide-roll ratios of two contact sides are opposite and the slide-roll ratio of the nut side can be reduced by increasing helix angle. Besides, increasing tooth number of the roller thread has little effect on the slide-roll ratios.