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AssigneeSchwarzkopf Development Corporation
InventorsRudolf Glatzle, Ronald Huber, Thomas Schopf, Michael Schretter
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The invention relates to an extrusion process and an extrusion tool for the production of cylindrical metallic or ceramic blanks having one or more internal twisted longitudinal bores. A plasticized, pulverulent starting material, deformable by means of extrusion, is forced through a space formed by a die and a mandrel. One or more twisted central pins of a rigid material are fastened to the mandrel which ends before the inner space of the die. The central pins form the longitudinal bores in the blank. The positioning of the longitudinal bores is extremely symmetrical within the blank and uniformly achieved in the various individual blanks extruded using the same production batch.
An extruded cylindrical metallic or ceramic blank having a smooth surface and one or more internal twisted longitudinal bores prepared by a powder-metallurgical process, the process comprising the step of extruding a deformable powdered metallic or ceramic starting material through a space formed by a die and a mandrel, the mandrel having one or more rigid, helically twisted central pins for forming the internal twisted longitudinal bores in the blank, which pins protrude from the mandrel into the die in the direction of the exit end of the die.
Dependencies are inferred from the claim text.