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US 4,733,970 AGranted
Extruder screw
AssigneeSterling Extruder Corporation
InventorLucien D. Yokana
Life of this patent
Estimating the term…
Abstract
Extruder screw having a feed section, compression section and metering section. The compression section includes two transition portions with a barrier flighted portion disposed therebetween. The screw reduces the power consumption and stock temperature of thermoplastic material.
Claims11
An extruder screw having a helical flight of predetermined outside diameter for extruding thermoplastic materials, comprising:
- (a) a feed section having a constant screw root diameter;
- (b) a compression section which includes:
- (i) a first transition portion immediately following said feed section, wherein the screw root diameter increases in the direction of extruder throughput;
- (ii) a barrier flighted portion immediately following said first transition section wherein said flight splits to form a first main flight of non-increasing screw root diameter and a second barrier flight of such a pitch that said barrier flight and the main flight in front of it are separated by a decreasing distance along the screw in the direction of extruder throughput such that material flows backward over said barrier flight;
- and
- (iii) a second transition portion following said barrier flighted section wherein the screw root diameter increases in the direction of extruder throughput;
- and
- (c) a metering section immediately following said compression section and having a constant screw root diameter.
5 more elements
A method of extruding thermoplastic materials comprising the steps of:
- (a) introducing thermoplastic polymer solids into an extruder feed section;
- (b) compressing said polymer while working said polymer to form a melt pool portion;
- (c) separating the melted portion of said compressed polymer from the remaining solids in a barrier flighted screw section while continuing to work said solids without additional compression in said barrier flighted screw section to form additional melt portions which are thereafter separated from the solids;
- (d) further compressing said melted portion prior to extrusion.
1 more element
Dependencies are inferred from the claim text.