Method for manufacturing a drive wheel bearing device

A method for manufacturing a drive wheel bearing device comprising:

• an outer member having double-row outer races on an inner periphery thereof;
• an inner member including double-row inner races opposite the outer races of the outer member, a first inner member, and a second inner member formed with at least one of the double-row inner races, the first inner member and the second inner member being inseparably coupled together at a radial swaged portion that is formed by a radially outward plastic deformation of the first inner member;
• double-row rolling elements interposed between the outer member and the inner member;
• and
• a constant velocity joint including an outer joint member fitted to an inner periphery of the first inner member such as to transmit torque, the swaged portion being in contact with the outer joint member in an axial direction, wherein the method is characterized in that:
• the swaged portion is formed in a manner as a non-hardened region, and in a manner that variations based on a reference surface in the axial direction of the flat surface are restricted within +/−0.2 mm, wherein the reference surface is provided with an end face on an outboard side of a flange for an attachment of a wheel or an end face on an inboard side of the flange for attachment to a vehicle body, and part of the swaged portion making contact with the outer joint member is formed into a flat surface,
• serrations and a pilot part are formed on an inner periphery of the first inner member, the serrations have a large diameter part and small diameter part, the pilot part is located on the inboard side of the serrations, and the inner diameter of the pilot part is larger than the inner diameter of the large diameter part of the serrations, and an inner peripheral surface of the pilot part is formed as a turned surface, and the turned surface has been turned after performing the inseparable coupling of the first inner member and the second inner member by forming the swaged portion,
• the outer joint member has a serrated shaft formed on the outer joint member for transmitting torque to and from the first inner member through the serrations and an outer periphery surface opposing to the pilot part, the serrated shaft has a large diameter part and small diameter part, and the outer diameter of the outer periphery surface opposing to the pilot part is larger than the outer diameter of the small diameter part of the serrated shaft, and
• a surface hardened layer is formed on the outer joint member by heat treatment in a region that includes at least the serrated shaft.