Continuous extrusion of metals

Abstract

A continuous extrusion machine in which feedstock in particulate or comminuted form is admitted to a peripheral groove formed in a rotating wheel member, is enclosed in that groove by a cooperating shoe member, is frictionally dragged along the arcuate passageway formed by said groove and a projecting portion of said shoe member towards an abutment member carried by said shoe member, and is continuously extruded as a metal product through a die orifice disposed at the downstream end of that passageway. A cooling device is provided downstream of the abutment member. The passageway comprises (a) a primary zone extending downstream from the inlet end of the passageway, in which primary zone the particulate or comminuted feedstock is compacted, by rotation of said wheel member, to progressively eliminate voids in the advancing feedstock and so form an agglomerated mass of feedstock metal, and (b) an adjoining, substantially shorter, secondary zone disposed downstream of the primary zone and extending at least to the die orifice, in which secondary zone said mass of metal is progressively compressed, by rotation of the wheel member, to a desired extrusion pressure sufficient to extrude said mass of metal though the die orifice. The radial depth of the passageway is substantially unchanging in the primary zone, and decreases gradually in the secondary zone in the direction of rotation of the wheel member at a relatively high rate and in such manner as to produce in that zone adjacent the die orifice a metal flow pattern more closely resembling that which is achievable with feedstock in solid form.