Eastman-kodak Company

Stephen J Derezinski

Stephen T Faulkenberry

Brian Mark Fauci

Don T Ras

A vented, multi-staged rotary screw extruder is taught for extruding thermoplastic materials. The screw has a final pumping-section of the screw that includes two or more channel depths which provides exit-pressure and flow stability. The channel-depth of the first segment of the final pumping-section is deeper than the channel depth of the second segment of the final pumping-section. The axial length of the first segment is preferably about two-thirds (&frac23;) of the final pumping-section length. The deeper first channel-depth acts as a reservoir resulting in smaller fluctuations in axial final fill-length as the input flow to the total pumping-section varies. The second channel-depth in the remaining approximate one-third (&frac13;) of the total pumping-section is preferably sized so as to optimize pressure development.

Multi-staged vented extrusion screw with dual channel depth pumping section

A barrel contains an extruder conveying screw which has a drive end, a feed section, a melting section and a pumping section wherein the screw has a vent hole located from 0 to 2 screw diameters from the beginning of the feed section. An axial bore in the screw vents gases from the barrel through the gas vent hole and into the axial bore.

Vented single stage barrier screw with a gas vent hole and axial bore in the screw for venting gases

Vented single stage barrier screw with a gas vent hole and axial bore in

A plasticizing method uses an apparatus (10) including a barrel (12) having a bore (14) therethrough. An auger (24) and a rotor (30) are positioned in the bore, each extending from opposed ends (16, 18) of the barrel (12) and having ends (26, 34) that are substantially flush. The auger (24) conveys particulate plastic material along the bore (14), the plastic being frictionally melted before passing the auger discharge end (26). The rotor (30) is provided to uniformly heat the melted plastic. Auger (24) and rotor (30) each are associated with independent means for rotating (28, 32) and means for controlling the speed of rotation (50, 52). The speed of rotation of the auger (24) controls the flow rate of plastic through the bore, and the speed of rotation of the rotor (30) controls the temperature of the melted plastic.

Method for plasticizing particulate plastic material

A plasticizing apparatus (10) including a barrel (12) having a bore (14) therethrough. An auger (24) and a rotor (30) are positioned in the bore, each extending from opposed ends (16, 18) of the barrel (12) and having ends (26, 34) that are substantially flush. The auger (24) conveys particulate plastic material along the bore (14), the plastic being frictionally melted before passing the auger discharge end (26). The rotor (30) is provided to uniformly heat the melted plastic. Auger (24) and rotor (30) each are associated with independent means for rotating (28, 32) and means for controlling the speed of rotation (50, 52). The speed of rotation of the auger (24) controls the flow rate of plastic through the bore, and the speed of rotation of the rotor (30) controls the temperature of the melted plastic.

Apparatus for plasticizing particulate plastic material

The present invention is a criss-cross flow hopper which provides even fluid distribution. The flow hopper includes the first and second hopper half each having a planar surface and a cavity which cooperate to form an inner chamber and an exit slot. A first and second insert are securable to each hopper half in the cavity. These non-contacting inserts form within the chamber first and second half flow slots which direct fluid away from the exit slot but then the fluid combines in a damping chamber bounded by the inserts. The fluid is then directed to the exit slot to the substrate to be coated.

Criss-cross hopper including non-contacting inserts

A criss cross coating hopper 10 is provided which is capable of producing uniform flow distribution patterns. The hopper 10 is comprised of a first and second hopper halves 12,14. First and second hopper halves 12,14 each have a first and second planar surface 20,40, respectively, adjoining a first and second cavity 22,42, respectively, each cavity 22,42 having a land surface 28,50 near the entrance end 26,48 and exit end 24,46. Inserts 62,64 are positioned against the land surface 60 of the first hopper half 12 and the land surface 50 of the second hopper half 14, respectively. The first and second hopper halves 12,14  and the inserts 62,64 cooperate to form an exit slot 69 recessed into first and second planar surfaces 20,40.

Coating hopper with criss-cross flow circuit

An extrusion apparatus 10 for extruding thermoplastic materials comprises a hollow cylindrical barrel 12 having a preferably smooth inner cylindrical wall 14. An extrusion screw 16 is mounted for rotation about an axis 18 within hollow barrel 12. The extrusion screw 16 has a major diameter, a minor diameter defining a minor circumferential surface (MCS) of the screw 16, and material pushing threads that are spaced axially and have a normal height `h` extending outwardly from the MCS of the screw into rotatable contact with the inner cylindrical wall 14 of the barrel 12.

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Penfield, NY, United States of America

Stephen J Derezinski