| 摘要 |
PROBLEM TO BE SOLVED: To enhance strength and durability of a cage. SOLUTION: A pocket 4c of the cage 4 comprises a pair of axial direction wall surfaces 4c1 facing in the direction of axis of the cage 4, a pair of circumferential wall surfaces 4c2 facing in the circumferential direction, and a corner radius section 4c3 which joins the axial direction wall surfaces 4c1 and the circumferential wall surface 4c2 together. Ratio (R/d) of a radius of curvature of the corner radius section 4c3 as opposed to a diameter d of a torque transmission ball 3 is turned into a limit value of 0.45<=R/d<=0.62, and the circumferential wall surface 4c2 and the corner radius section 4c3 are configured to form one arc having a radius of curvature R. In addition, as to the axial direction wall surface 4c1, variations of machining allowances are made small by performing grinding process or hardened steel cutting operation, after the heat treatment (carburizing and quenching, and tempering) of the cage 4.
|
