Patent ID: 8631581

Claim:
A method for forming a wheel bearing apparatus comprising: an outer member integrally formed, on its inner circumference, with double row outer raceway surfaces; an inner member including a wheel hub and at least one inner ring, the inner member is formed with a double row inner raceway surfaces on its outer circumference to be arranged opposite to the double row outer raceway surfaces, the wheel hub has a wheel mounting flange integrally formed at one end, a cylindrical portion extends axially from the wheel mounting flange, the inner ring is press-fit onto the cylindrical portion of the wheel hub; double row rolling elements are rollably contained between the inner and outer raceway surfaces of the inner member and the outer member; the inner ring is axially rigidly secured by a caulking portion, the caulking portion is formed by plastically deforming the cylindrical portion of the wheel hub radially outward; a face-spline for transmitting torque is formed on an end face of the caulking portion; an end portion of the cylindrical portion is pre-formed as a cylinder prior to its plastic deformation to form the caulking portion; a caulking tool includes a punch and a swing shaft, the punch has a nose portion projecting from a bottom surface of the punch at its center, the nose is adapted to abut against an end portion of the cylinder at a predetermined inclined angle (β) relative to an inner circumferential surface of the cylinder, teeth are formed around the nose portion to form the face-spline by plastically deforming the end face of the caulking portion, and the swing shaft rigidly secures the punch so that a phase of the punch is not shifted relative to the wheel hub, the swing shaft has a central axis (A) forming a predetermined inclined angle (α) relative to a central axis (L) of the wheel hub; and the face-spline is formed simultaneously with the formation of the caulking portion by advancing the caulking tool toward the wheel hub and pushing the punch against the end portion of the cylinder with a predetermined working force, and a main shaft having a rotational axis corresponding to the central axis of the wheel hub is rotated to cause a swing motion of the caulking tool.