Ball screw device and method for manufacturing same

A ball screw device comprising:

• a screw shaft having a thread portion having a spiral shaft-side ball screw groove on an outer peripheral surface, and a fitting shaft portion arranged on one side in an axial direction of the thread portion;
• a nut having a spiral nut-side ball screw groove on an inner peripheral surface;
• a plurality of balls arranged between the shaft-side ball screw groove and the nut-side ball screw groove;
• and
• a fitting member externally fitted onto the fitting shaft such that rotation relative to the fitting shaft portion is not possible;
• the fitting shaft portion having an inner-diameter side engaging portion on an outer peripheral surface in which a plurality of external teeth are arranged in a circumferential direction;
• the fitting member having an outer-diameter side engaging portion on an inner peripheral surface in which a plurality of internal teeth are arranged in the circumferential direction, the outer-diameter side engaging portion engaging with the inner-diameter side engaging portion;
• an engaging portion between the inner-diameter side engaging portion and the outer-diameter side engaging portion including a portion having interference in a radial direction in a portion of the engaging portion in the axial direction;
• and
• the fitting shaft portion having a crimped portion at an end portion on the one side in the axial direction that engages in the axial direction with the fitting member.