| 摘要 |
PROBLEM TO BE SOLVED: To provide a ball screw device hardly causing increase in dynamic friction torque even when a nut shrinks due to cooling and hardly causing excessive reduction in processing efficiency or increase in loss of pressure by increasing cooling effect as much as possible. SOLUTION: The ball screw device is provided with a screw shaft 10, the nut 20, and a cooling means 40. The nut 20 is screwed to the screw shaft 10 through the medium of a plurality of rolling elements 30, and the cooling means 40 is used for cooling the nut 20. The plurality of rolling elements 30 are incorporated in the space between the thread groove 10a of the screw shaft 10 and the thread groove 20a of the nut 20, and a pre-load applied on the plurality of rolling elements 30 in a state of two-point contact by making the pre-load direction a tensile direction. The ratio (L/D) between the length L in the axial direction of a through hole 20b which is formed in the axial direction of the nut 20 and the diameter D of the through hole 20b which is formed in the axial direction of the nut 20 is made 10≤L/D≤60. COPYRIGHT: (C)2010,JPO&INPIT |
