Roller follower, valve train, induction hardening apparatus, method of heat treatment of shaft member, method of manufacturing shaft, and shaft

摘要

A roller follower includes a roller ring, a shaft and a plurality of rollers. At least one of the roller ring, the shaft and the rollers is a steel member made of steel containing 0.7 to 2.4% carbon and 10.0 to 20.0% chromium, with remainder iron and impurities. In addition, carbide containing at least any one of iron and chromium as well as carbon and having an area of 12.6 μm2 or greater is generated at an area ratio of 5.0% or higher, at a rolling contact surface of the steel member (a roller ring rolling contact surface, a shaft rolling contact surface and a roller rolling contact surface.

主权项

1. A roller follower interposed between a rocker arm and a cam for opening and closing a valve of an engine and arranged in contact with said cam, comprising:
an outer ring having an annular shape; a shaft arranged such that a rolling contact surface formed on its outer circumferential surface is opposed to a rolling contact surface formed on an inner circumferential surface of said outer ring; and a plurality of rolling elements coming in contact, at a rolling contact surface formed on an outer circumferential surface thereof, with the rolling contact surfaces of said outer ring and said shaft and arranged on an annular raceway, at least any one of said outer ring, said shaft and said rolling elements being a steel member made of SUS440C steel defined under JIS containing carbon not lower than 0.7 mass % and not higher than 2.4 mass % and chromium not lower than 10.0 mass % and not higher than 20.0 mass %, with remainder iron and impurities, carbide containing at least any one of iron and chromium as well as carbon and having an area of 12.6 μm2 or greater being generated at an area ratio of 6.0% or higher, at said rolling contact surface of said steel member, and the number of carbides each containing at least one of iron and chromium as well as carbon, and each having an area exceeding 530.7 μm2 is not more than one when five fields of 120 μm×100 μm in a cross-section perpendicular to the rolling contact surface of the steel are examined.