Abstract: Disclosed is a ball for a constant velocity joint, and a method for producing the same. The ball for a constant velocity joint is produced via a quenching step for heating a spherical body consisting of a material corresponding to a high carbon chromium bearing steel regulated by Japanese Industrial Standards (JIS) to 840-900° C. and then cooling the spherical body under such a condition as 10-25 vol. % of austenite remains up to a first part where the depth from the surface is 0.1 mm, a step for tempering the spherical body at 150° C. or more, and a step for shot peening the spherical body and imparting a compression residual stress of ?1000 MPa or more to a region reaching second part where the depth from the surface is 0.2 mm.

Abstract: A needle bearing functioning as a rolling element comprises a uniform-diameter body part and bottom surfaces shaped in flat surfaces. A tapered reduced-diameter part and a chamfered part are interposed between the body part and the bottom surface. A gentle reduction in diameter is first made by the tapered reduced-diameter part, and then a relatively sharp reduction in diameter is made by the chamfered part. Consequently, in the needle bearings adjacent to each other, their tapered reduced-diameter parts are separated from each other.

Abstract: Disclosed is a ball for a constant velocity joint, and a method for producing the same. The ball for a constant velocity joint is produced via a quenching step for heating a spherical body consisting of a material corresponding to a high carbon chromium bearing steel regulated by Japanese Industrial Standards (JIS) to 840-900° C. and then cooling the spherical body under such a condition as 10-25 vol. % of austenite remains up to a first part where the depth from the surface is 0.1 mm, a step for tempering the spherical body at 150° C. or more, and a step for shot peening the spherical body and imparting a compression residual stress of ?1000 MPa or more to a region reaching second part where the depth from the surface is 0.2 mm.

Abstract: A needle bearing functioning as a rolling element comprises a uniform-diameter body part and bottom surfaces shaped in flat surfaces. A tapered reduced-diameter part and a chamfered part are interposed between the body part and the bottom surface. A gentle reduction in diameter is first made by the tapered reduced-diameter part, and then a relatively sharp reduction in diameter is made by the chamfered part. Consequently, in the needle bearings adjacent to each other, their tapered reduced-diameter parts are separated from each other.