Apparatus for extruding polymeric material

Claim 2

In a machine for processing polymeric material comprising a cylinder; said cylinder having die means at one end thereof; a feed screw rotatably mounted in said cylinder and extending longitudinally therethrough for moving plastic material therethrough to progressively change said plastic material from the solid phase to a fluent phase for extrusion therefrom; said feed screw having first means for operatively exerting continuous pressure on said plastic material for moving said plastic material; second means integral with said feed screw for continuously leading off the fluent phase progressively from said first means as the plastic material is changed from the solid phase by contact with said cylinder, said fluent phase being directed away from and not through the remaining solid phase; and said first means defines a groove having a constant axial width with decreasing radial depth in the direction of said die means providing a constant amount of surface area exposed to said cylinder for material carried by said groove.

Claim 3

In a machine for processing polymeric material as set forth in claim 1 wherein said second means has a groove which progressively increases in cross-sectional dimension toward said die means.

Claim 4

In a machine for processing polymeric material comprising a cylinder; said cylinder having a die means at one end thereof; a feed screw rotatably mounted in said cylinder for moving plastic material therethrough to progressively change said plastic material from the solid phase to a fluent phase for extrusion therefrom; said feed screw having first means for operatively exerting continuous pressure on said moving plastic material; second means integral with said feed screw for continuously leading off the fluent phase progressively changed from the solid phase by contact with said cylinder, said fluent phase being directed away from and not through the remaining solid phase; said first means defines a groove having a constant axial width to maintain a constant amount of the solid phase of the moving plastic material to contact said cylinder; said second means has a groove which progressively increases in cross-sectional dimension toward said die means; said groove of said first means is defined by the leading face of primary flight and the trailing face of a secondary flight; and said primary flight having a greater clearance between the uppermost edge portion of said primary flight and said barrel than the uppermost edge portion of said secondary flight.

Claim 5

In a machine for processing polymeric material comprising a cylinder; said cylinder having a die means at one end thereof; a feed screw rotatably mounted in said cylinder for moving plastic material therethrough to progressively change said plastic material from the solid phase to a fluent phase for extrusion therefrom; said feed screw having first means for operatively exerting continuous pressure on said moving plastic material; second means integral with said feed screw for continuously leading off the fluent phase progressively changed from the solid phase by contact with said cylinder, said fluent phase being directed away from and not through the remaining solid phase; said first means defines a groove having a constant axial width to maintain a constant amount of the solid phase of the moving plastic material to contact said cylinder; said second means has a groove which progressively increases in cross-sectional dimension toward said die means; said groove of said first means is defined by the leading face of primary flight and the trailing face of a secondary flight; and said primary flight having a greater clearance between the uppermost edge portion of said primary flight and said barrel than the uppermost edge portion of said secondary flight.

Claim 6

In a machine for processing polymeric material as set forth in claim 3 wherein the bottom surface of said groove of said first means merges with said uppermost edge portion of said primary flight to provide a clearance space that is equal to said clearance space provided between said uppermost edge portion of said primary flight and said barrel.

Claim 7

In a machine for processing polymeric material as set forth in claim 3 wherein the bottom surface of said groove of said first means defines a terminal portion that provides a clearance space closely adjacent to the merging of said first means with said second means at the terminal upstream end thereof that is approximately equal to the clearance space between said uppermost edge portion of said primary flight and said barrel.

Claim 8

In a machine for processing polymeric material as set forth in claim 5 wherein clearance space defined by said terminal portion of said first means in cooperation with the interior wall of said barrel is constant for a portion of said groove of said first means.