BEARING DEVICE FOR WHEEL

摘要

A third generation type bearing device for a wheel, whose cycle fatigue strength is enhanced by relaxing stress concentration occurring at a recess of a hub ring. A hardened layer (20) by heat treatment is formed at the surface of a carbon steel hub ring (2), at at least a part from a raceway surface (2a) to a flange root. The recess (2e) as a circumferential groove is provided in the hardened later (20), along that corner of the hardened layer (20) which is formed by a raceway surface (2b) and a large flange surface (2d) with which end faces of rollers (5) are in contact. The recess (2e) is formed by turning, and the inner surface of the recess (2e) is cut or ground after the hardened layer (20) is formed. As a result, compression residual stress is applied to the hardened layer (20).