Method for manufacturing rolling bearing unit

A manufacturing method for a rolling bearing unit that comprises:

• a main hub body and an inner ring;
• the main hub body having an inner-ring raceway on one side in the axial direction of the rolling bearing unit that is provided around an outer-circumferential surface of a middle section in the axial direction of the main hub body, a cylindrical section that is provided on a portion near the end on the other side in the axial direction of the main hub body, and a crimped section that is provided on an end section on the other side in the axial direction of the main hub body and extends outward in the radial direction from the end section on the other side in the axial direction of the cylindrical section;
• the inner ring having an inner-ring raceway on the other side in the axial direction around an outer-circumferential surface of the inner ring, and fitting around the cylindrical section;
• and
• the crimped section having a surface on the one end in the axial direction that constrains a surface on the other end in the axial direction of the inner ring, and a surface of the other end in the axial direction on which hub-side face splines are provided;
• the manufacturing method for a rolling bearing unit comprising;
• a step of forming the hub-side face splines on the surface of the other end in the axial direction of the crimped section by using a roll having a center axis that is inclined with respect to the center axis of the main hub body and a processing surface provided with plural teeth, and with the processing surface of the roll pressed against the surface of the other end in the axial direction of the crimped section, causing the roll to rotate around the center axis of the main hub body, and causing the roll to rotate around the center axis of the roll due to engagement between the processing surface of the roll and the surface of the other end in the axial direction of the crimped section;
• when causing the roll to rotate around the center axis of the main hub body with the processing surface of the roll pressed against the surface of the other end in the axial direction of the crimped section, spacing of the teeth that are formed on the processing surface at a location in the radial direction of a portion of the processing surface of the roll where the tip end of one of the teeth formed on the processing surface of the roll first comes in contact with the surface of the other end in the axial direction of the crimped section, and spacing of teeth of the hub-side face splines at a location in the radial direction of a portion of the surface of the other end in the axial direction of the crimped section where the surface of the other end in the axial direction of the crimped section first comes in contact with the tip end of the one of the teeth formed on the processing surface of the roll being made to coincide.