| 摘要 |
PROBLEM TO BE SOLVED: To provide a ball screw which can smoothly move balls in a return passage of a circulating part.SOLUTION: A ball screw comprises: a screw shaft 1 having a spiral ball rolling groove 1a at an external peripheral face; a nut 2 having a spiral load ball rolling groove 2a which opposes the ball rolling groove 1a at an internal peripheral face; a circulation part 4 in which at least a part of a return passage 7 which connects one end and the other end of the load ball rolling passage 2a of the nut 2 is formed; and a plurality of balls 3 which can circulate. A contact part 8 contacting with the balls 3 at two or more points is formed at an external peripheral side of the return passage 7 of the circulation part 4. The contact part 8 of the circulation part 4 is twisted conforming to a change of a centrifugal force which acts on the balls 3. |
