Fundamental study on tapered roller screw - Design for infinitesimal slip and verification of mechanical efficiency

Abstract

The roller screw mechanism is more suitable for high load than the ball screw mechanism, because it has a large contact area and a greater radius of curvature between a roller and a screw shaft. However, it is considered that the rolling mechanism which has large contact surface is easy to get a big slip ratio, and it generally has lower mechanical efficiency. In this study, to improve the mechanical efficiency of the roller screw mechanism, we devised the tapered roller screw mechanism (TRS). The shape of flank face of screw shaft and the surface of rollers of TRS is designed to minimize the slip ratio. As a result of experiment, if was confirmed that the apparent coefficient of friction was 0.0018 at minimum, and the mechanical efficiency was 0.985 at maximum. These results showed that the TRS was comparable to the ball screw mechanism in efficiency.