Patent ID: 8950283
Filing Date: 2015-02-10
Classification: B21J,B21K,F16H,Y10T

Abstract:
1. A method for manufacturing a nut for a ball screw, the ball screw comprising: the nut having an inner circumferential surface on which a spiral groove is formed; a threaded shaft having an outer circumferential surface on which a spiral groove is formed; balls loaded in a raceway between the spiral groove of the nut and that of the threaded shaft; and a ball return passage arranged as a concave on the inner circumferential surface of the nut for returning the balls from an end point of the raceway to a start point of the raceway, the balls being rolling in the raceway to make the nut relatively move with respect to the threaded shaft, wherein the concave is formed on the inner circumferential surface of the nut blank by plastic working in a pressing method by use of a die of a cam mechanism, the cam mechanism comprising: a cam driver inserted into a cylindrical nut blank and moving in an axial direction of the nut blank at the time of processing; and a cam slider disposed between the nut blank and the cam driver and provided with a convex corresponding to the concave, a movement of the cam driver causing the convex to move in a radial direction of the nut.