Finish Form Rolling of Sintered Fe Alloy Gears Using Screw-Shaped Tool

Abstract

The purpose of this study is to optimize the finish rolling process of sintered Fe alloy gears (P/M gears) using a screw-shaped tool to improve the tooth profile accuracy and the load carrying capacity. In this article, finish rolling experiments of unmodified P/M gears using an unmodified screw-shaped tool are firstly carried out to investigate the fundamental rolling properties. The porosity in the surface layer of rolled gear teeth is reduced to the target level, but the tooth profile becomes heavily concave. Secondary, modified P/M gears with a convex tooth profile are rolled to improve the tooth profile accuracies. Gears with a good tooth profile and a good surface finish are obtained by optimizing the amount of radial feed of the tool. Finally, simultaneous rolling of tooth and fillet surface of unmodified gears using a modified screw-shaped tool are carried out. It is confirmed that the rolled tooth profile are scarcely affected by the amount of rolling stock and the tooth surface and the fillet at the root of gears are successfully consolidated in one rolling pass using this method.