US 4,012,477 AGranted

Method for producing plastic sheet or film stock

AssigneeAskco Engineering Corporation

InventorsErich Beck, Albert C. Robbins, John C. Birdsall

Life of this patent

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Abstract

Method of extruding a plastic film using a single roll which is rotatably and horizontally mounted between spaced-apart supporting members, each having curved recesses partially accommodating and encompassing opposite portions of the circumference of the roller. Molten plastic is distributed along the length of the roller, and the roller is preferably revolved to carry the molten plastic through the first recess to the second recess, whereby a substantially equal accumulation of plastic is collected in each recess and at opposite locations on the surface of the roller. The second accumulation of plastic is further located at a die aperture in the adjacent one of the two supporting members, whereby plastic from the second accumulation is extruded through the die aperture to form the sheet stock sought to be produced. The first accumulation of plastic which is squeezed between the other support member and the roller provides a force on the roller which equals and offsets the force being applied to the roller by the second accumulation of plastic, whereby the roller is protected against bending or other lateral deformation.

Claims14

Dependent claims

A method of producing a thermoplastic sheet material using a single rotating roll extruder rotating in one direction longitudinally between first and second supporting members each having concave confining surfaces, comprising,

depositing a thermoplastic resin in a first substantially semi-circular chamber tapering in the direction of roll rotation and formed by the peripheral surface of said extruder roll and said concave surface of said first supporting member,
accumulating plasticized resin in said first chamber for creating a first pressure therein against said surface of said roll extruder and said first supporting member,
squeezing plasticized resin from said first chamber and into a second substantially semi-circular chamber formed by the peripheral surface of said extruder roll and said concave surface of said second supporting member and tapering in the direction of roll rotation into a slot-like extrusion orifice in said second supporting member,
accumulating an equal amount of plasticized resin in said second chamber for establishing and maintaining a second pressure therein against said surfaces of said roll extruder and said second supporting member equal to said first pressure, and
squeezing plasticized resin from said second chamber into said extrusion orifice in said second supporting member while maintaining balancing and opposing pressures in said chambers and on said extruder roll and allowing said roll to float between said chambers.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 05/567,256Filed 11 Apr 1975 · division
Priority: 16 Nov 1972
Granted: 15 Mar 1977
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

B29B 7/523
With rollers or the like, e.g. calenders: co-operating with casings
B29C 48/465
Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die: using rollers
B29C 48/08
Flat, e.g. panels: flexible, e.g. films
B29B
Preparation or pretreatment of the material to be shaped