| 摘要 |
This invention relates to improvement of a ball screw unit in which a nut member meshes with a screw shaft via a plurality of balls circulating endlessly. The balls are disposed freely rotatably in line at a predetermined interval in a ball arranging member formed in a belt-like shape. If a relative rotation occurs between the nut member and screw shaft, the balls circulate in the infinite circulation path with the ball arranging member. Guide pieces are projected to both sides of the ball arranging member and guide grooves for accommodating each of the guide pieces are formed along the entire circumference of the infinite circulation path. Therefore, the ball arranging member is introduced by the guide grooves and circulates in the infinite circulation path without being fluttered.
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