Patent ID: 8511903

Claim:
A wheel bearing device comprising: a flanged shaft member including a shaft portion in which a rolling bearing is assembled; a fitting shaft portion formed on one end side of the shaft portion and fitted to a center hole of a wheel; and a plurality of flange portions extending radially outward on an outer peripheral surface located between the shaft portion and the fitting shaft portion, and the plurality of flange portions including a through bolt hole in which a hub bolt for fastening the wheel is arranged, wherein each flange portion in the plurality of flange portions are formed through a side extrusion when a forged recess is formed by cold forging of a center at an end surface of the fitting shaft portion, and each flange portion includes an edge portion that is formed into a rounded surface, the edge portion being a cross-sectional shape of each flange portion, and the edge portion being perpendicular to a longitudinal direction of each flange portion.