| 摘要 |
A ball screw, which improves its durability under circumstances where a radial load and a moment load are applied to it, has a screw shaft ( 2 ) formed with a helical screw groove ( 2 a) on its outer circumferential surface. A nut ( 3 ) is adapted to mate with the screw shaft ( 2 ). The nut ( 3 ) is formed with a helical screw groove ( 3 a) on its inner circumferential surface. The nut helical screw groove ( 3 a) corresponds to the screw shaft screw groove ( 2 a). A number of balls ( 4 ) are rollably contained within a ball rolling passage formed by the oppositely arranged screw grooves ( 2 a , 3 a). Bridge members ( 5 ), each formed with a connecting groove ( 5 a) on its inner circumferential surface, connect the screw grooves ( 3 a) of the nut ( 3 ). A contact angle (a) between each ball ( 4 ) and one or both the screw grooves ( 2 a , 3 a) is set within a range of about 20~40°.
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