Cold header pierced valve stem

摘要

A method of cold forming a plumbing and heating valve stem by providing a cylindrical blank workpiece, axially stamping the workpiece to circumferentially reduce and axially lengthen a portion of the workpiece, axially stamping the circumferentially larger portion to form a circumferentially enlarged head on the larger portion, while punching a central axial cylindrical cavity in the head to a depth no greater than the axial thickness of said head, and then axially punching the cylindrical axial cavity to a depth greater than the thickness of the head and also stamping a central cylindrical axial cavity into the opposite end, forming self tapping screw cavities. The larger portion is then provided with rolled threads.