Certainteed Corporation

Saint-gobain Industrial Ceramics, Inc.

Steven H Bowens

David Steele

James N Valentine

Thomas A Gates

Anthony L Owoc

Donn L Briskie

Arthur A Hendrick

The present invention includes a screw tip for an extruder screw for effecting mixing in an extruder. The screw tip has a shaft portion and at least one mixing element ring connected to the shaft portion, or a mixing element having an aperture therethrough, or both. The mixing element may have two legs connected by a top portion with the aperture between the two legs to allow flow of extrudate therethrough.

Dynamic mixer screw tip

The present invention includes a screw tip for an extruder screw for effecting mixing in an extruder. The screw tip has a substantially conical outside surface and at least one discontinuous fin. The at least one fin protrudes from the outside surface of the screw tip.

Wear resistant extruder screws and methods for their manufacture are provided. The extruder screws include a base alloy screw body having a plurality of flights, a major outer diameter and a minor inner diameter. Each of the flights includes a pair of flight sides disposed between the major outer diameter and the minor inner diameter. The flight sides and minor inner diameter define a root area proximate to their juncture. The preferred extruder screws of this invention include a bond coating layer having a thickness of about 1-10 mils disposed over a major portion of the extruder screw which includes the root area, and a wear resistant coating layer having a thickness of about 10-100 mils disposed over said bond coating layer. The wear resistant coating layer preferably has an ASTM G65 dry abrasion wear rating of less than 10 mm /kilometer, or, in further embodiments, the bond coating layer has a coefficient of thermal expansion which is in between that of the wear resistant coating layer and the base alloy.

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West Chester, PA, United States of America

Steven H Bowens