Load distribution of planetary roller screw mechanism with different installations

A model for calculating load distributions of threads in Planetary Roller Screw Mechanism (PRSM) with different installations is developed, in which the shaft stiffness, thread stiffness and contact stiffness of screw, rollers and nut in PRSM are taken into consideration. The proposed model is verified in comparison with an existing model. The effects of installations, load conditions, structural parameters and thread form parameters on the load distributions of threads are studied thoroughly. The results and their analysis show preliminarily that: (1) The main factors which affect the load distribution are material parameters, structural parameters and installation; (2) The accumulative axial deformations of screw and nut are the main reasons which cause the uneven distribution of loads acting on threads; (3) The load distribution among threads becomes slightly evener when the thread stiffness is decreased; (4) The tooth number of rollers and pitch of the threads will remarkably affect the load distribution, and the load distribution will be more uneven with the increase of the tooth number or pitch.