| 摘要 |
PROBLEM TO BE SOLVED: To provide a ball screw device with a screw shaft for preventing the fall-off of balls and a nut member while avoiding trouble such as bending or non-uniformity of the effective diameter of a screw groove, and to provide rolled dies to be used for manufacturing the screw shaft. SOLUTION: The ball screw device 10 comprises the screw shaft 11 having the screw groove rolled in the outer peripheral face, the nut member 12 through which the screw shaft 11 is inserted and which has a screw groove formed in the inner peripheral face opposed to the outer peripheral face of the inserted screw shaft 11, and the plurality of balls 13 mounted to be free to roll between the screw groove of the screw shaft 11 and the screw groove of the nut member 12. The screw groove of the screw shaft 11 is shaped to be cut throughout the axial periphery of the screw shaft 11 in pitches different from the pitches of the screw groove of the nut member 12, at least at one axial end 18 of the screw shaft 11. COPYRIGHT: (C)2007,JPO&INPIT
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