Patent ID: 6282971
Filing Date: 2001-09-04
Classification: F16H,Y10T

Abstract:
A ball screw comprising:a screw shaft formed, on an outer peripheral surface thereof, with a spiral ball rolling groove;a nut member having an inner peripheral surface on which a spiral loaded ball rolling groove corresponding to said spiral ball rolling groove of the screw shaft is formed, said both spiral grooves constituting a loaded ball rolling passage in combination when said screw shaft is fitted to said nut member;a number of balls rolling in the loaded ball rolling passage; andat least one return pipe having one end connected to one end of the loaded ball rolling passage and another end connected to another end of the loaded ball rolling passage so as to scoop the balls rolling in the loaded ball rolling passage at the one end of the return pipe and return the balls to the loaded ball rolling passage at the another one end of the return pipe, said return pipe having both opened end portions in which cutouts, each having a width gradually reduced towards inside the return pipe, are formed, said balls being guided by both sides of said cutouts and being gradually led into the inside of the return pipe,wherein said return pipe is arranged so that center lines of both the opened end portions of the return pipe are substantially tangential to a track center line of the balls, and said one end of the return pipe encloses the ball about a circular path of more than 180.degree. of arc at a point tangential to the track center line of the balls, said one end of the return pipe extending within said track center line at both ends of said circular path.