| 摘要 |
PROBLEM TO BE SOLVED: To provide a top-type ball screw which can utilize a large number of regions as rolling passages more than a conventional top member, and can reduce a size of a nut while securing a sufficient number of the rolling passages, related to a spiral screw groove which is formed at an internal peripheral face of the nut.SOLUTION: In a top-type ball screw having: a screw shaft in which a spiral screw groove is formed at an external peripheral face; a nut 13 which is arranged around the screw shaft, and has a spiral screw groove 14 at an internal peripheral face; a plurality of balls accommodated in a rolling passage 22 which is formed of the opposing two screw grooves; and a circulation path for circulating the balls from one end of the rolling passage 22 to the other end, an outside guide face constituting the circulation path is formed at a top member 16, and an axial guide face is formed at a side face of a top window 15 of the nut 13.SELECTED DRAWING: Figure 2 |
