(under subclass 266) Method or means wherein the extrusion chamber comprises a cavity in a cuplike member, into which cavity a deforming element constituting a combined plunger and internal-forming means is movable, the cavitated member being closed to work material flow except for an annular orifice formed between the cavity wall and the element periphery when in operative position so that upon movement of said element further into said cavity the work flows backward around the element as a tubular product corresponding in shape to the internal configuration of the cavitated member and the external configuration of the element.
(1) Note. The element (usually a plunger), the chamber
means, the bottom, per se, of the chamber means, or any combination of these parts may move to perform the pressing operation.
(2) Note. The operation here performed is known by several names, among which are: Impact extrusion, Backward extrusion, and Cold Squirting.
SEE OR SEARCH THIS CLASS, SUBCLASS:
257, for a device of this type in combination with a stripper or ejector.
362+, for forging into a closed die which may result in backward flow but without extrusion.
