Patent ID: 6978693
Filing Date: 2005-12-27
Classification: F16H,Y10T

Abstract:
1. A ball screw, comprising: a shaft having a spiral-shaped shaft groove in an outer circumferential surface thereof; a nut having a spiral-shaped nut ball groove corresponding to the shaft groove in an inner circumferential surface thereof and screwed with the shaft via a plurality of balls, the plurality of balls rotatably charged in a spiral-shaped ball rolling passage defined between the nut ball groove and the shaft groove; and, a ball circulation passage for raking the plurality of balls at one end of the ball rolling passage and sending to the other end thereof, wherein an end part of the ball circulation passage is connected to one end part of the ball rolling passage in such a manner that: a gap Δt formed between a ball contacting part of the nut ball groove contacted with the ball and an inner circumferential surface of the end part of the ball circulation passage is set 0.2 mm or less; and a change of angle in a ball rolling direction is 10° or less, the change being caused by raking the ball from the ball rolling passage to the ball circulation passage.