Low-energy extruder-pump system

Claim 1

A double-flighted melter screw (12) for use in an extruder in combination with a gear pump (40) to form a melting and pumping system, said melter screw being characterized in that it comprises successively an inlet feeding section (16), a transition section (18), a metering section (20) and a mixing section (22), each of said feeding, transition and metering sections having a substantially equal outer diameter, thread width and lead, high thread pitch in the feeding, transition and metering sections, decreasing root depth of the threads of said transition section between relatively deep root depth (HF) in said feeding section (16) to relatively shallow root depth (HM) in said metering section (20); said mixing section (22) having a plurality of flutes (26) formed by alternate groove and land means arranged to extend substantially longitudinally in the surface thereof and capable of effecting substantially complete melting and mixing of the material before discharge from the extruder.

Claim 5

A method for the extrusion of synthetic thermoplastic materials comprising passing such materials continuously to and through a rotary extruder having successive feeding, transition, metering and mixing sections; characterized in that the extruder screw (12) forms the feeding, transition and metering sections, in cooperation with the cylindrical interior of the outer extruder housing (O), has equal outer diameter, thread width and lead, high thread pitch in the feeding, transition and metering sections, decreasing root depth of the threads of said transition section between relatively deep root depth (H F ) in said feeding section (16) to relatively shallow root depth (HM) in said metering section (20), said mixing section (22) having a plurality of flutes (26) formed by alternate groove and land means arranged to extend substantially longitudinally in the surface thereof and capable of substantially complete melting and mixing of the material before discharge from the extruder; and wherein the extrudate from said extruder is successively passed through a breaker plate (34) and an upstream adapter member (36), to the inlet (38) of a rotary gear pump (40) which, in turn, discharges, through a downstream adapter member (50), to a die (54).

Claim 6

A method for the extrusion of synthetic thermoplastic materials comprising passing such materials continuously to and through a rotary extruder having successive feeding, transition, metering and mixing sections; characterized in that the extruder screw (12) forms the feeding, transition and metering sections, in cooperation with the cylindrical interior of the outer extruder housing (O), has equal outer diameter, thread width and lead, high thread pitch in the feeding, transition and metering sections, decreasing root depth of the threads of said transition section between relatively deep root depth (H F ) in said feeding section (16) to relatively shallow root depth (HM) in said metering section (20), said mixing section (22) having a plurality of flutes (26) formed by alternate groove and land means arranged to extend substantially longitudinally in the surface thereof and capable of substantially complete melting and mixing of the material before discharge from the extruder; and wherein the extrudate from said extruder is successively passed through a breaker plate (34) and an upstream adapter member (36), to the inlet (38) of a rotary gear pump (40) which, in turn, discharges, through a downstream adapter member (50), to a die (54).

Claim 11

A method for the extrusion of synthetic thermoplastic materials comprising passing such materials continuously to and through a rotary extruder having successive feeding, transition, metering and mixing sections; characterized in that the extruder screw (12) forms the feeding, transition and metering sections, in cooperation with the cylindrical interior of the outer extruder housing (10), has equal outer diameter, thread width and lead, decreasing root depth of the threads of said transition section between relatively deep root depth (H F ) in said feeding section (16) to relatively shallow root depths (H M ) in said metering section (2Q), said mixing section (22) having a plurality of groove means arranged to extend substantially longitudinally in the surface thereof, said groove means open at the upstream ends and closed at the downstream ends, hollow internal passage means positioned axially within said mixing section over a substantial portion.of its terminal length, and a plurality of radial inlet conduits communicating between said internal passage means and the exterior of said mixing section, said inlet conduits being positioned between a pair of lands (28) which are positioned, in turn, between said groove-means; and wherein the extrudate from said extruder is successively passed.through a breaker plate (34) and an upstream adapter member (36), to the inlet (38) of a rotary gear pump (40) which, in turn, discharges, through a downstream adapter member (50), to a die (54).

Claim 12

A method for the extrusion of synthetic thermoplastic materials comprising passing such materials continuously to and through a rotary extruder having successive feeding, transition, metering and mixing sections; characterized in that the extruder screw (12) forms the feeding, transition and metering sections, in cooperation with the cylindrical interior of the outer extruder housing (10), has equal outer diameter, thread width and lead, decreasing root depth of the threads of said transition section between relatively deep root depth (H F ) in said feeding section (16) to relatively shallow root depths (H M ) in said metering section (2Q), said mixing section (22) having a plurality of groove means arranged to extend substantially longitudinally in the surface thereof, said groove means open at the upstream ends and closed at the downstream ends, hollow internal passage means positioned axially within said mixing section over a substantial portion.of its terminal length, and a plurality of radial inlet conduits communicating between said internal passage means and the exterior of said mixing section, said inlet conduits being positioned between a pair of lands (28) which are positioned, in turn, between said groove-means; and wherein the extrudate from said extruder is successively passed.through a breaker plate (34) and an upstream adapter member (36), to the inlet (38) of a rotary gear pump (40) which, in turn, discharges, through a downstream adapter member (50), to a die (54).