A study of precision grinding of micro-pitch internal thread for planetary roller screw mechanism

Abstract

Planetary roller screw mechanism (PRSM) is a new type of precision-heavy-duty threaded transmission mechanism. The thread profile accuracy directly determines the transmission accuracy and bearing capacity of PRSM. The PRSM nut has characteristics such as micro-pitch, hard tooth surface, and small aperture inner surface forming, and its precision grinding is a huge challenge. In this study, a systematic experimental study on the precision grinding of micro-pitch internal threads of PRSM was conducted, including grinding wheel dressing, grinding wheel installation, and grinding process parameters, and a numerical model for the PRSM nut grinding with multiple errors such as center distance error and installation angle error was established, aiming to explore the relationship between grinding wheel dressing-installation-grinding process parameters and the profile accuracy of micro-pitch nuts. The results show that the dressing amount has a significant impact on the shape of the grinding wheel. The installation angle of the grinding wheel and the linear velocity of the grinding wheel have a greater impact on the internal thread profile, and corresponding optimal parameter combinations are proposed. This study provides support for efficient and precise machining of micro-pitch PRSM nuts in engineering practice.