| 摘要 |
<p>To provide a third generation type wheel support bearing assembly in which a stress concentration in a recess in a hub axle can be reduced, and the repeated fatigue strength can be increased. A hardened layer is provided by means of a heat treatment at least in a portion from a raceway in a surface portion of a hub axle made of a carbon steel to a flange root portion. A recess as a circumferential groove is formed along a corner portion defined between a raceway in the hardened layer and a large collar with which an end face of a roller contacts. The recess is formed by means of a lathe turning work, after formation of the hardened layer and then undergoes machining or grinding within an inner surface thereof, thereby causing a compressive residue stress to the hardened layer.</p> |
