Consolidation of surface layer and improvement of surface durability of sintered Fe alloy rollers by finish rolling

摘要

If gear-shaped preforms of sintered Fe alloy can be finished by a cold forming process and enough load-carrying capacity can be secured, the production process of automotive transmission gears will be shortened and their total production costs greatly reduced. The purpose of this study is to examine the practical application of a finish rolling process using a screw-shaped tool to consolidate the surface layer of sintered Fe alloy gear teeth and improve the surface fatigue durability and the bending fatigue durability. In this study, preliminary rolling experiments using sintered Fe alloy rollers are carried out. A roller is installed on a work holder whose axis is set at a right angle to the rolling tool axis. The target consolidation level of the surface layer of the roller can be achieved by setting the amount of rolling stock to more than 250 μm. A two-roller fatigue test proves that the surface fatigue durability is greatly improved by finish rolling.