US 4,383,764 AGranted

Apparatus for continuous extrusion without reverse flow of material

OwnerLeon Sloininventor

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Abstract

An apparatus for continuous extrusion of a material including a hollow barrel with inner liner having a cylindrical chamber portion and an outwardly divergent, coaxial frusto-conical outlet chamber portion adjacent thereto so that reverse pressure developed by extrusion of the material results in sealing engagement of the frusto-conical screw and barrel portions thereby effectively preventing regurgitation of the material. A fluted screw is rotatably positioned coaxially within the barrel and liner, and has both cylindrical and outwardly divergent outer thread surface portions conforming to the inner surface of the cylindrical and the frusto-conical chamber portions, respectively, of the barrel and liner. Rotation of the screw forces the material to flow axially through the barrel along the threads of the screw toward the outlet chamber portion and through an extrusion die. Resistance of the die to the flow of material results in a force in the reverse direction being exerted on the threads of the frusto-conical chamber portion establishing an effective, fluid-tight seal to prevent reverse flow or regurgitation of the material between the screw and the barrel liner.

An apparatus for continuous extrusion of a material without reverse flow of material, comprising:

a hollow barrel having a cylindrical chamber portion and a frusto-conical chamber portion diverging outwardly from said cylindrical chamber portion;
a threaded screw rotatably positioned coaxially within said hollow barrel, said screw having a threaded cylindrical screw portion located within said cylindrical chamber portion and a threaded frusto-conical portion located within said frusto-conical chamber portion diverging from said cylindrical screw portion, said screw threads defining a cylindrical outer surface conforming to the inner surface of said cylindrical chamber portion and a tapered outer surface conforming to the inner surface of said frusto-conical chamber portion;
inlet means for feeding the material into said hollow barrel;
driving means coupled to said screw for rotating said screw within said barrel so as to force the material to flow axially through said barrel in a forward direction toward an outlet end of said barrel adjacent said frusto-conical chamber portion opposite said cylindrical chamber portion;
outlet means connected to said outlet end of said barrel for expelling the material accompanied by a reverse pressure resulting from the resistance of said outlet means to said forward flow of the material,
said tapered outer surface of said screw cooperating with said inner surface of said frusto-conical chamber portion and forming a seal in response to said reverse pressure exerting a force on said threads of said frusto-conical portion in a direction opposite to said forward flow of the material, whereby reverse flow of the material between said screw and barrel in said opposite direction is prevented;
and
adjusting means coupled to said screw for axially displacing said screw by a predetermined amount thereby controlling the contact between said tapered outer surface of said screw and said inner surface of said frusto-conical chamber portion.

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Abstract

Claims14