Abstract: Provided is a method of manufacturing a hollow power transmission shaft, which makes it possible to ensure stable quality even when there is a difference in wall thickness or hardening ratio along an axial direction thereof. A hollow shaft material (1?) is provided with, on an outer peripheral surface (1g) side thereof, for example, a movable induction heating coil (5) wrapped therearound. While a high-frequency current with a predetermined frequency is caused to flow through the induction heating coil (5), the induction heating coil (5) is axially moved to perform induction hardening of the hollow shaft material (1?) from the outer peripheral surface (1g) side.

Abstract: To further reduce the manufacturing cost of a shell type needle roller bearing, and to ensure high quality of the shell type outer ring by subjecting the outer ring to a heat treatment that needs no adjustment of the atmosphere. The steel sheet to be formed into the shell type outer ring 1 by pressing is made of a medium to high carbon steel containing carbon by not less than 0.3 mass percent. With this arrangement, the material cost and thus the manufacturing cost are lower than when using a conventional low-carbon structural alloy steel sheet or a steel sheet for cold rolling and pressing. Also, it is possible to ensure high quality of the outer ring by subjecting the outer ring to simple heat treatment without the need for carburizing or carbonitriding, which needs adjustment of the atmosphere.

Abstract: A roller bearing assembly includes an outer race (1) prepared from a steel plate and a plurality of rollers (2) wherein the outer race (1) has a raceway surface (1a) to which induction hardening and tempering are applied. The outer race (1) is a shell type. In addition to the raceway surface (1a), an inner surface of an annular collar (6) at one end of the outer race (1) is also subjected to the induction hardening and tempering. An opposite annular collar (7) is left as a raw material without being heat treated so that it can be easily bent.