Ball screwed nut, linearly guiding apparatus using the same, and ball screw for steering, and method of manufacturing ball screwed nut

摘要

A ball rolling groove 1c is defined in an inner peripheral surface of A ball screwed nut 1 by a rolling process, not by a grinding process so that a ball screwed nut having small diameters or large leads can be manufactured. The surface of the ball rolling groove 1c is finished to be sharp without concave and convex by a plastic working by the rolling process, so that the surface is less rough. By rolling the surface by the rolling process excellent in durability, the precision of R shape of the ball rolling groove 1c can be made excellent.