Patent ID: 8661679

Claim:
A method of manufacturing a bearing device for a wheel, wherein the bearing device includes an inner ring member that includes an inner shaft and an inner ring constituent member fitted to a periphery of the inner shaft, an outer ring member that is disposed around a periphery of the inner ring member concentrically with the inner ring member, a rolling element that is rollably provided between the inner ring member and the outer ring member, and a wheel-mounting flange that protrudes outward, and that is formed on a peripheral surface of the inner shaft at a position close to an outer end portion of the inner shaft in a vehicle-width direction, the method comprising: forming the inner shaft so that an outside diameter of the inner shaft at a first portion is smaller than the outside diameter of the inner shaft at a second portion which is adjacent to the first portion, and the first portion extends from an inner portion of a base of the wheel-mounting flange in the vehicle-width direction toward an inner end portion of the inner shaft in the vehicle-width direction, and the first portion has a predetermined length in an axial direction; heat-treating the peripheral surface of the inner shaft at the first portion while the peripheral surface of the inner shaft at the second portion is not heat-treated; and finishing the peripheral surface of the inner shaft at the first portion and the second portion by lathe turning whereby a step is not formed at a border between the first portion and the second portion because the outside diameter of the inner shaft at the heat-treated first portion is smaller than the outside diameter of the inner shaft at the non-heat-treated second portion.