US Patent 7125173 Bearing device

In a bearing device in which a free end of a shaft body to which a rolling bearing is mounted is bent outward in its radial direction into a shape to be pushed against an end face of an inner ring of the rolling bearing so as to prevent the rolling bearing from falling out, a raceway surface of the inner ring of the rolling bearing is subjected to hardening treatment, and another portion of the inner ring is made of raw material which is not hardened. With this arrangement, the caulked portion formed by the caulking plastically deforms the relatively soft inner peripheral corner of the inner ring and as a result, the caulked portion and the inner peripheral corner are adhered to each other strongly.