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United States Patent 4964730
Douris , ê et al.

Plasticating extruder screw

Alzner , Ê et al. October 23, 1990

Abstract

A plasticating extruder screw incorporates two or more screw configurations into a single screw. This is accomplished with two or more parallel channels in which each channel is designed to a different set of materials and performance requirements reflecting the range of the materials to be processed. The extrusion screw in fact represents two or more screws in a single screw in which each performs its function independently of the other. Thus, each channel in this screw differs from the others in critical design parameters such as compression ratio, length and depth of its feed, transition and metering zones. This multiconfigurational design feature may occupy part or the entire length of the extruder as dictated by the specific characteristics of the materials to be processed. A mixing and stabilization zone placed at or near the entrance of the metering zone of the screw provides for melt flow interaction and equilibration between channels. The screw terminates in a metering zone comprised of one or more channels designed in accordance with known principles.