YOKE OF STEERING UNIVERSAL JOINT

摘要

PROBLEM TO BE SOLVED: To provide a yoke of a steering universal joint which is further enhanced in mechanical rigidity.SOLUTION: In a yoke 1 of a steering universal joint, nitriding treatment for oil-cooling or water-cooling a root of an arm part 3 at cooling is applied to a fitting hole 2A of a base part 2, and a dimension D in a radial direction of a region 10 in which residual stress at the other end part 2b of the base part 2 is -100 MPa or less, and an inside diameter d of the fitting hole 2A satisfy a relationship of D-d≥1.0(mm). It is preferable that the surface hardness Hv of a nitrogen diffusion layer of the fitting hole 2A is 300 or higher, and also a thickness of a compound layer of the fitting hole 2A is 30μm or less, and the dimension D and the inside dimension d of the fitting hole 2A satisfy a relationship of D-d≥2(mm).