| 摘要 |
PROBLEM TO BE SOLVED: To provide a ball screw which is used over a long time, causing no deterioration of acoustic characteristics, even in high speed use conditions by restricting early breakage or deterioration of positioning functions of a positioning protrusion protruded from a ball guide member. SOLUTION: In this ball screw, a ball return passage 17 is opened in each end surface of a nut 14, a ball guide member 19 to guide a ball 15 rolling along a ball rolling passage 16 or the ball return passage 17 to the ball return passage 17 or the ball rolling passage 16 is provided on each end of the nut 14, and a positioning protrusion to be engaged with a hole part formed in an end surface of the nut 14 or the ball return passage 17 is provided on the ball guide member 19. Where protruded quantity of the positioning protrusion is I, with diameter Dw of the ball 15, the ratio between the protruded quantity of the positioning protrusion and the diameter of the ball is set to satisfy 0.1≤(I/Dw)≤0.3. COPYRIGHT: (C)2004,JPO
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