| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a ball screw which requires small energy needed in manufacturing and has a long service life while hardly causing operation sound, wear and torque fluctuation. <P>SOLUTION: The ball screw 1 includes a screw shaft 3, a nut 5, a plurality of balls 9 mounted in a ball-rolling passage 7 so as to be freely rolled, and a ball circulation passage 11 for returning the balls 9 from the end point to the start point of the ball rolling passage 7 to circulate the balls. The ball circulation passage 11 is constituted of a recessed groove 22 formed by partially recessing the inner circumferential face of a columnar face of the nut 5 by plastic working. In the ball circulation passage 11, both ends 11a, 11a to be connected to the ball rolling passage 7 are in a straight-line form, while an intermediate part 11b located between the both ends 11a, 11a is in a curved line form. The groove width ta in the both ends 11a, 11a of the ball circulation passage 11, the groove width tb of the intermediate part 11b and the diameter Da of the balls 9 satisfy an expression of Da≤ta≤tb<1.05Da. <P>COPYRIGHT: (C)2012,JPO&INPIT |
