CLOSED CHAMBER EXTRUSION METHOD AND APPARATUS FOR SHAPING OF METAL ROD INTO TULIP-SHAPED PART

摘要

A tulip-shaped metal part such as a yoke component of a tri-port type constant velocity universal joint is manufactured by single-stage closed chamber extrusion of a solid cylindrical metal rod. The metal rod is inserted into two opposingly engaged dies to protrude into a space defined in the dies and is axially pressed against an impressed surface to cause gradual and continuous cleavage of the rod into three branched portions, which are forced into three chambers arranged and shaped correspondingly to three petal-like arms of the tulipshaped metal part. The branched portions of the metal material are extruded within the three chambers in directions parallel to the direction of the pressing force exerted on the metal rod, with continued application of a back pressure to the extruding portions of the metal material to shape the ends of the petal-like arms during the extrusion-process.