Load distribution and radial deformations for planetary roller screw mechanism with axial load, radial load and turning torque

AbstractAbstractObtaining the load distribution and radial deformations of planetary roller screw mechanism (PRSM) for the load carrying capacity design under complex loading conditions (multi-directional loads) is beneficial to decelerate fatigue and wear of threads. However, the combined effects of axial load, radial load and turning torque (overturning moment) were ignored in previous studies due to the complicated structure of PRSM. This paper presents a multi-roller beam-bar-spring (MR-BBS) model that incorporate radial load, turning torque and thread modification. The proposed model extended the theoretic method for calculating bending behavior of screw and rollers, which can more precisely describe the locus of the threads and roller axis. The load distribution of threads and load sharing among rollers of a PRSM under different external loads and cycling process are analyzed. The results show that the load distribution is more sensitive to turning torque of screw but relatively insensitive to the radial load. Moreover, the load distribution moderately changes with the variation of modification factor. Based on thread modification, the variable lead PRSM is proposed so that the uniformity of load sharing with complex load can be optimized. HighlightsA multi-roller beam-bar-spring (MR-BBS) model is developed that incorporate axial load, radial load, turning torque and thread modification.The load distribution of threads and load sharing among rollers of a PRSM under different external loads and cycling process are analyzed.The load distribution is more sensitive to turning torque of screw but relatively insensitive to the radial load.The variable lead PRSM is proposed so that the uniformity of load sharing with complex load can be optimized.Keywords: Planetary roller screw mechanismcomplex loadingload distributionnonlinear springbending deformation AcknowledgementsWe gratefully acknowledge the valuable cooperation of Mr. Xinping Shan (R&D Center, Seenpin Robot Technology Co. Ltd., Hangzhou, P.R. China) in provision of experimental equipment.Declaration of interest statementThe authors report there are no competing interests to declare.Additional informationFundingThe work was financially supported by the National Natural Science Foundation of China (Grant No. 52075053) and the National key research and development program of China (Grant No. 2020YFB2010204)