| 摘要 |
<p>[Problem] In a shaft member of a wheel rolling bearing device, local concentration of stress (stress concentration) which is generated by a load applied to flange portions that are formed by cold forging is suppressed. [Means for Resolution] A flange portion 21 which is formed by cold forging is configured by an outer flange portion 21d and an inner flange portion 21a. As viewed in the axial section, the inner flange portion 21a is formed to be thicker than the outer flange portion 21d. The shape of a flange surface which is on a side where a bolt seat is disposed is formed as the shape of a vertical surface which has a constant length in a radial direction, in the position of a radially basal end portion, and as the shape of an inclined surface 21c which becomes gradually thinner from the position of the shape of the vertical surface toward the radially outer side. In a plan view as viewed from the side of a shaft portion 10, a first flange surface joining portion 21f between the inclined surface 21c and the outer flange portion 21d is formed as a concave curved portion which surrounds a bolt hole 24 for a hub bolt 27.</p> |
