Wheel bearing device and manufacturing method therefor

摘要

A wheel bearing device of the invention includes a flanged shaft member (1) that includes a shaft portion (10) to which a rolling bearing (41) is assembled, a fitting shaft portion (30) that is formed on one end side of the shaft portion (10) and that is fitted to a center hole of a wheel, and a plurality of flange portions (21) that extend radially outward on an outer peripheral surface located between the shaft portion (10) and the fitting shaft portion (30) and each of which has a through bolt hole (24) in which a hub bolt (27) for fastening the wheel is arranged. Each flange portion (21) of the wheel bearing device is formed by side extrusion when a forged recess (33) is formed at a center of an end surface of the fitting shaft portion (30) by cold forging. An edge portion (21e) of a cross-sectional shape taken perpendicularly to a longitudinal direction of each flange portion (21) is formed in an R-chamfered shape.