Determining the parameters of rolling screw mechanisms

Planetary roller screw mechanisms used in instrument drives are considered. Based on theoretical analysis, the dependences of the helix angles of the screw and roller, torque, linear speed of the nut and required power on various combinations of the number of passes, the average diameter of the screw and the number of rollers are obtained. The axial force is calculated taking into account the load unevenness coefficient, and the results of determining the stressstrain state of the most loaded mating pair of turns using the finite element method are presented. The problem is solved in a static approximation for an axisymmetric formulation without taking into account friction in contact; numerical modeling is performed using the Abaqus package. It is established that an increase in the overall size and number of rollers reduces the load on the most loaded pair of turns from 102.25 to 51.12 N, and the maximum linear speed of the nut for the 20 × 12 version reaches 0.6 m/s at a frequency of 3000 rpm. The maximum von Mises stress is 118 MPa, which is below the yield strength of ShKh15 steel. The presented results are recommended for engineering calculations at the stages of preliminary selection of transmission geometry and design of roller screw drives of devices.