Patent attributes
An inner ring is configured to simultaneously ensure the strength thereof and the dimensional accuracy of a female spline portion of a shaft hole thereof in the case where the female spline portion is subjected to heat treatment. Also it is configured to suppress the backlash of spline fit with a shaft. The inner ring is mounted in a constant velocity universal joint for transmitting torque while the inner ring is allowed to be angularly displaced relative to an outer ring and is spline-fitted to a shaft inserted into a shaft hole formed through the inner ring. The inner ring has a hardened layer by means of heat treatment which is formed only in an axial central portion of the shaft hole, but is not formed in remaining inner diameter surface other than the axial central portion.
