Load Distribution and Axial Static Rigidity for Planetary Roller Screw Mechanism

This paper presents the algebraic method for calculating the static load distribution and axial stiffness of the standard planetary roller screw mechanism (PRSM). In view of the problem of insufficient accuracy of the calculation results of the PRSM stiffness in the past, according to the Hertz elastic contact theory, the roller is taken as the research object. And three kinds of deformations are theoretically analyzed and calculated, including roller screw and the point contact between the thread groove of the Hertz deformation; roller screw and nut in contact with axial deformation; screw and nut, with the roller contact deformation when thread. Based on the analysis of the load distribution for PRSM, a new mathematical model of stiffness is established. A typical planetary roller screw mechanism is taken as example to analyze the load distribution, and the validity of the model is verified by simulation.