| 摘要 |
PROBLEM TO BE SOLVED: To provide a ball screw, in particular of a large lead, capable of sufficiently securing durability life even when used for applications under strict conditions such as a high load with high speed rotation. SOLUTION: This ball screw is provided with a screw shaft 52 having a spiral ball rolling groove 55 in an outer circumferential surface, a nut 53 having a spiral ball rolling groove 56 in an inner circumferential surface, and a plurality of balls 54 disposed in a track 57 formed of the ball rolling groove 55 in the screw shaft 52 and the ball rolling groove 56 in the nut 53 facing each other. A lead angleθof the track 57 is set to be 15°or more, and a Gothic arc groove is employed for at least either of the ball rolling groove 55 of the screw shaft 52 and the ball rolling groove 56 of the nut 53 in the ball screw 51. Where diameter of the ball 54 is set as Dw, the radius of curvature of an arc forming the Gothic arc groove is set within a range of 51%Dw or more and 53%Dw or less. A spacer 58 is provided between the balls 54. COPYRIGHT: (C)2005,JPO&NCIPI
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