Process of closed extrusion shaping of a metal rod material and an apparatus therefor

A process for manufacturing parts having yokes with two or more body portions wherein the breadth of the root portion of each body portion in the transverse direction is smaller than the breadth of the center portion or the top end portion of each body portion in the transverse direction, from a metal solid rod material by extrusion shaping which comprises pressing a solid metal rod material from one end into a chamber formed by two opposing dies, with the other end of the rod being urged into contact with an impression and associated projecting portions formed in one of said dies to divide the rod material into two or more body portions which are then extruded into cavities in said one die communicating with said chamber and extending parallel to the pressing direction, and applying back pressure to the top end surface of each body portion to fill the chamber including said impression with the extruder material.

An apparatus for shaping a metal solid rod material into parts having yokes with two or more body portions by closed extrusion, which comprises two opposing dies forming a chamber and a punch pressing the metal solid rod material into said chamber from one end, one of said two dies being provided with a guide hole for guiding the rod material, said guide hole extending through said one die in the perpendicular direction to the contact surface of said dies, and the other of said dies being provided with an impression and projecting portions opposed to said guide hole, which contact the top end portion of said rod material and divide said rod material into two or more body portions, and a plurality of cavities in said other die for receiving and guiding the divided rod material in the direction parallel to said guide hole, said punch being axially movable in the guide hole.