| 摘要 |
PROBLEM TO BE SOLVED: To provide a ball screw mechanism in which a load applied to a rolling ball is small, an entire load balance is excellent, and durability of a return tube is high.SOLUTION: A ball screw mechanism (1) includes a return tube (2) for circulating a ball, including a pair of leg portions (10, 10), and a communicating portion (11) for connecting between the leg portions. A ball passage (13) in the return tube (2) is linearly formed in the leg portions (10), and connected to a rolling raceway (8) so as to match a lead angle (&bgr;) of a spiral of the rolling raceway (8), and correspond to a tangential direction of the rolling raceway (8) when observed from an axial direction of a ball screw (3). Two connecting portions (16, 16) between the ball passage (13) and the rolling raceway (8) are positioned so as to have an angle less than 180 degrees to a central axis when observed from the axial direction of the ball screw (3). |
