| 摘要 |
<p>An object of this invention is to further improve durability, ball circulation performance, and working performance of a ball screw having a groove-shaped ball return passage (ball circulation groove). The ball screw is provided with: a threaded shaft (201) having a spiral groove (201a) at its outer circumferential surface; a nut (202) having a spiral groove (202a) which faces the spiral groove (201a) at its inner circumferential surface; a plurality of balls (203) rotatably loaded in a spiral raceway constituted by the two spiral grooves (201a, 202a) ; and a ball circulation groove (241) which returns and circulates the balls (203) from an end point to a start point of the raceway. Further, the edge portions (241c) constituted by the two side surfaces (241b, 241b) of the ball circulation groove (241) and the surfaces (242) which continue from the side surfaces (241b) and extend in the axial direction are formed to be rounded.</p> |
