| 摘要 |
PROBLEM TO BE SOLVED: To provide a top-type ball screw which is suppressed in a leak amount of a lubricant to the outside while achieving cost reduction in a space-saved manner, and high in reliability.SOLUTION: In a top-type ball screw having a top member 5 in which a connecting groove 5a is formed which is fit to a top window 6 protrusively formed at a flank of a nut 3, and has a rolling passage as a circulation passage at an internal periphery, a pair of arms 9 are protrusively formed at both sides of an internal peripheral side, and the arms 9 are engaged with and positioned at a screw groove 3a of the nut 3, the pair of arms 9 of the top member 5 are formed into forms which follow along a lead of a screw groove 2a of a screw shaft 2, and set so as to be in non-contact with a groove bottom of the screw groove 2a, a collection port 12 for collecting a lubricant to one arm 9 out of the pair of arms 9, and a discharge port 13 for discharging the lubricant which is collected to the other arm 9 are formed, a communication groove 14 for making the collection port 12 and the discharge port 13 communicate with each other is formed, and a flow passage for circulating the lubricant is formed.SELECTED DRAWING: Figure 3 |
