A roller taper modification method for load distribution optimization of planetary roller screw mechanism

Abstract

Planetary roller screw mechanism (PRSM) is a novel high-performance linear transmission device. The non-uniformity of load distribution over PRSM threads is a vital problem severely affecting its load-carrying capacity and service performance. This work aims to develop a PRSM load distribution improvement approach with good manufacturability and general applicability. A roller taper modification method for load distribution optimization is proposed based on the deformation compatibility and force equilibrium, then the roller grinding experiment is carried out. Finally, the effects of external load and thread number on load sharing optimization are analyzed to examine the applicability. The results show that the maximum reduction in load sharing coefficient reaches 31.4% after roller taper modification under the case studied. The taper modification of roller threads could be rapidly implemented by only adjusting the roller grinding angle. The roller grinding experiment results agree well with the theoretical values, and the maximum error is no more than 2 μm. As the external load and thread number change, the improvement approach still works well. The proposed method has been verified by comparisons with finite element simulations and available references. This work can provide theoretical guidance for the optimal design of PRSM and has good engineering application prospects.

Keywords

• planetary roller screw mechanism transmission
• deformation compatibility
• load distribution design
• roller taper modification
• grinding angle