Patent ID: 6591657
Filing Date: 2003-07-15
Classification: B21H,B21K,F16C,Y10T

Abstract:
A method of producing a housing of a ball joint, the housing including an arm portion projecting therefrom and being adapted to support a ball stud, the method comprising:inserting a tap that has an external thread formed along a cylindrical outer surface thereof into a hole formed in an intermediate molding, the hole comprising a cylindrical inner surface having a diameter greater than a diameter of the tap, and forming an internal thread in the cylindrical inner surface by narrowing the diameter of the cylindrical inner surface of the hole containing the tap therein by cold forging, wherein the forming of the internal thread comprises providing a pair of pressure dies respectively having concave faces, formed at locations facing each other when the pressure dies are combined for the cold forging and each having a shape of a half cylinder corresponding to a half of a cylindrical outer surface of the arm portion that is split along the longitudinal central axis of the arm portion, the curvature of the concave faces being substantially equal to the curvature of the cylindrical outer surface of the arm portion, placing the intermediate molding between the concave faces and applying a pressure to the intermediate molding through the pressure dies containing the intermediate molding therein.