| 摘要 |
<P>PROBLEM TO BE SOLVED: To maintain stable connection between a hub ring and an outer coupling member by surely securing fixing force by a bolt member in a bearing device for a wheel configured such that separation of the hub ring and an outer coupling ring from each other is allowed. <P>SOLUTION: In this bearing device, protrusions axially extending are provided on a shaft part 11 of the outer coupling ring 4, and the shaft part 11 is press-fitted into a hole 20 of the hub ring 1. Through this press-fitting operation, recesses to be closely fitted on the protrusions are formed on the inside diameter surface of the hub ring 1 by means of the protrusions, and as a result, there is formed with recess-protrusion-fitting structure M wherein the protrusions are in close contact with the recesses over the whole fitting area. The hub ring 1 and the shaft part 11 of the outer coupling ring 4 are fixed to each other by a bolt member 37 in a state where it is allowed to separate the recess-protrusion-fitting structure M by providing an axial pull-out force. Furthermore, a bolt receiving surface 20e1 of the hub ring 1, on which a seat surface 37a1 of a head part 37a provided in the bolt member 37 abuts, is formed with a hardening layer H2 by heat treatment, and surface hardness thereof is made a subject of control, and an allowable value equal to or more than 50 HRC is given. <P>COPYRIGHT: (C)2012,JPO&INPIT |
