| 摘要 |
PURPOSE:To prevent a fracture by providing the nut of a ball screw with a movable member energized with a spring member in a direction opposite to a load and freely movable in an axial direction, and interrupting the rotation of a screw shaft upon the detection of the shift of the load direction with a sensing part. CONSTITUTION:When a load equal to or more than an allowable load is applied to a table 17 in an A-direction, the impact of the load is absorbed by a disc spring 21 via a movable plate 13, thereby preventing the direct transmission of the impact to a nut 11 and a screw shaft 10. Also, when the movable plate 13 shifts in the A-direction due to the application of the load equal to or more than the allowable load, a sensor 20 in an adjusting nut 18 detects the shift and stops the operation of a drive part 4 turning the screw shaft 10, thereby preventing the application of an excessive force to the screw shaft 10 and the nut 11. According to the aforesaid system, the fracture of the screw shaft 10 and the nut 11 can be prevented. |
