대표
청구항
▼
1. A thermally insulated extrusion die plate assembly for a pelletizer including a plurality of extrusion orifices through which process melt is extruded to exit at a cutting face as a strand to be cut into pellets by a moving cutting assembly which comprises: (a) a die plate body having a central portion, said central portion of said die plate body being cut out on a downstream face of said die plate body to form a recess or a cavity that is centrally positioned in said downstream face;(b) at least one ring of extrusion orifice extensions extending thro...
1. A thermally insulated extrusion die plate assembly for a pelletizer including a plurality of extrusion orifices through which process melt is extruded to exit at a cutting face as a strand to be cut into pellets by a moving cutting assembly which comprises: (a) a die plate body having a central portion, said central portion of said die plate body being cut out on a downstream face of said die plate body to form a recess or a cavity that is centrally positioned in said downstream face;(b) at least one ring of extrusion orifice extensions extending through said cavity;(c) a cover plate sized to fit over said cavity and having openings which mate with said extrusion orifices therethrough to form said cutting face, said over plate attached to said die plate body over said cavity; said cover plate and said cavity forming and defining a thermally insulating centrally positioned air chamber in said assembly adjacent said cutting face, said orifice extensions through-penetrating said air chamber to surround and insulate said orifice extensions to provide continuous heating along a length of the through-penetrating orifice extensions and to prevent heat loss from the process melt adjacent the cutting face; and(d) an air vent open to a surrounding atmosphere outside the die plate assembly so that pressure build up is prevented and air in said air chamber is maintained at a same atmospheric pressure as air in said surrounding atmosphere outside of said die plate assembly. 2. The assembly as claimed in claim 1, wherein the die plate body is a single-body construction that is thermally regulated by at least one of electrical resistance, induction, steam, and thermal transfer fluid. 3. The assembly as claimed in claim 1, wherein the die plate body is a two-piece construction including a removable insert and a die plate outer ring that are thermally regulated by at least one of electrical resistance, induction, steam, or thermal transfer fluid. 4. The assembly as claimed in claim 3, wherein said removable insert and said die plate outer ring are independently thermally regulated by at least one of electrical resistance, induction, steam, or thermal transfer fluid. 5. The assembly as claimed in claim 1, wherein the cutting face is a raised annular plane through which penetrate the multiplicity of extrusion orifices and a lower peripheral plane about each side of said raised annular plane, said raised annular plane being at least about 0.025 millimeters higher than the lower peripheral plane. 6. The assembly as claimed in claim 1, wherein said cover plate has a counter-bore which conforms to a shape of said extrusion orifice extensions to further define said thermally insulating air pocket. 7. The assembly as claimed in claim 6, wherein said extrusion orifice extensions are configured as a raised circular ridge continuous and unitary with said die plate body and individual orifice protrusions attached to and extending from said raised circular ridge to said cover plate. 8. The assembly as claimed in claim 7, wherein said raised circular ridge is configured to channel heat to said orifice protrusions. 9. The assembly as claimed in claim 7, wherein said raised circular ridge has a cross-section of trapezoidal shape. 10. The assembly as claimed in claim 7, wherein said cover plate counter-bore is sized so that the thermally insulating air chamber follows a contour of the raised circular ridge. 11. The assembly as claimed in claim 1, wherein the cover plate contains at least one circumferential expansion groove on at least one face. 12. The assembly as claimed in claim 11, wherein the cover plate contains a multiplicity of circumferential expansion grooves on both faces in a staggered and alternating configuration. 13. The assembly as claimed in claim 1, wherein the cover plate is made of a nickel steel and is weldingly attached by nickel steel. 14. The assembly as claimed in claim 7, wherein the cover plate is weldingly attached to distal ends of said orifice protrusions at the openings in said cover plate. 15. The assembly as claimed in claim 1, wherein the air chamber atmospherically equilibrated by said air vent is at least 0.05 millimeters in depth. 16. The assembly as claimed in claim 7, wherein the orifice protrusions are through-penetrated by a multiplicity of extrusion orifices arranged in at least one of groups, pods, and clusters. 17. The assembly as claimed in claim 7, wherein the orifice protrusions are separate elements attachedly connected to the raised circular ridge on the die plate body. 18. A thermally insulated extrusion die plate assembly for a pelletizer including a plurality of extrusion orifices through which process melt is extruded to exit at a cutting face as a strand to be cut into pellets by moving cutting assembly which comprises: (a) a die plate body having a downstream face, a portion of said downstream face being cut out to form a recess or a cavity that is centrally positioned in said downstream face;(b) a cover plate sized to mate with and fit over said cavity, said cover plate and said cavity together forming and defining a thermally insulating air chamber in said die plate assembly adjacent said cutting face, said air chamber in direct communication with a surrounding atmosphere outside the die plate assembly to keep air in said chamber at atmospheric pressure; and(c) at least one ring of extrusion orifice extensions encasing said extrusion orifices through which the process melt is carried from said die plate body to openings in said cover plate to form said cutting face, said extrusion orifice extensions configured as a raised circular ridge continuous and unitary with said die plate body; and(d) a plurality of individual orifice protrusions extending outwardly from said raised circular ridge, distal ends of said protrusions being attachedly connected to said cover plate adjacent said cover plate openings, said raised circular ridge and said orifice protrusions through-penetrating said air chamber and being surrounded and insulated by said air chamber to provide continuous heating along a length of said extrusion orifice extensions and to prevent heat loss from the process melt adjacent the cutting face. 19. The assembly as claimed in claim 18, wherein said assembly includes a vent configured to equilibriatingly vent said thermally insulating chamber to an ambient atmosphere outside of said die plate assembly to prevent pressure build up and/or vacuum formation in said air chamber. 20. The assembly as claimed in claim 18, wherein said raised circular ridge is configured to channel heat to said orifice protrusions and said cover plate has a counter-bore which conforms to a shape of said extrusion orifice extensions and is sized so that the thermally insulating chamber follows a contour of the raised circular ridge. 21. The assembly as claimed in claim 18, wherein said cover plate and said orifice protrusions include complementary abutting surfaces where said orifice protrusions are welded to said cover plate adjacent said cover plate openings. 22. The assembly as claimed in claim 1 in combination with a pelletizer. 23. The assembly in combination with a pelletizer as claimed in claim 22 wherein the pelletizer is an underwater pelletizer. 24. The assembly as claimed in claim 7, wherein the orifice protrusions comprise at least one geometry including oval, round, square, triangular, rectangular, polygonal, or combinations thereof, can be arranged concentrically alternating, staggeredly, linearly, or combinations thereof, and can be parallel to an arc of the cutting face or perpendicular to the arc. 25. The assembly as claimed in claim 7, wherein the orifice protrusions are separate elements attachedly connected to the raised circular ridge on the die plate body. 26. The assembly as claimed in claim 1, wherein the extrusion orifice outlets comprise a shape of round, oval, square, rectangular, triangular, pentagonal, hexagonal, polygonal, slotted, radially slotted and any combination thereof. 27. The assembly as claimed in claim 18 in combination with a pelletizer. 28. The assembly in combination with a pelletizer as claimed in claim 27 wherein the pelletizer is an underwater pelletizer. 29. A thermally insulated extrusion die plate assembly for a pelletizer including a plurality of extrusion orifices through which process melt is extruded to exit at a cutting face as a strand to be cut into pellets by a moving cutting assembly and cooled by cooling water on a downstream side of said cutting face, in which the die plate assembly comprises: (a) a die plate body having a downstream face that includes a center section and a generally circular periphery, said center section of said downstream face having a generally circular cutout formed therein, said circular cutout being inset from and generally concentric with said periphery of said die plate body downstream face and extending across said downstream face center section;(b) at least one ring of extrusion orifice extensions encasing said extrusion orifices through which the process melt is carried from said die plate body to said cutting face; and(c) a circular cover plate sized to mate with and fit over said circular cutout, said cover plate having holes that receive distal ends of said extrusion orifice extensions, said cover plate and said cutout together forming and defining an air chamber inset into the downstream face of the die plate body and closed by said cover plate, said air chamber surrounding and thermally insulating said extrusion orifice extensions and said die plate body from heat loss that could otherwise occur due to a temperature of the cooling water adjacent said die face. 30. The assembly as claimed in claim 29, wherein said air chamber extends between and on either side of the extrusion orifice extensions, said extrusion orifice extensions dividing the air chamber into an outer section and an inner section. 31. The assembly as claimed in claim 29, wherein said extrusion orifice extensions are configured as a raised circular ridge continuous and unitary with said die plate body and having individual orifice protrusions extending from said raised circular ridge, distal ends of said orifice protrusions being attachedly connected to said cover plate adjacent said cover plate holes. 32. The assembly as claimed in claim 31, wherein said raised circular ridge is configured to channel heat to said orifice protrusions. 33. The assembly as claimed in claim 29, wherein said assembly includes a vent configured to equilibriatingly vent said air chamber to a surrounding atmosphere outside of said die plate assembly. 34. An underwater pelletizer for extruding and cutting a process melt into pellets comprising: a die plate body with a plurality of extrusion orifices formed therein through which the process melt is carried from said die plate body to a cutting face on a downstream side of said die plate body;a rotary cutter blade assembly in opposed relation to said cutting face, said cutter blade assembly having a hub and at least one cutter blade mounted on said hub and capable of moving in a plane generally parallel to and closely adjacent said cutting face to cut strands of process melt extruded through said orifices into pellets;a water box having a cutting chamber enclosing said cutting face and cutter blade assembly, said water box including a water inlet for introducing cooling water into the cutting chamber and an outlet for discharge of water and pellets entrained in the water;said die plate body having a portion of its downstream face cut out to form a recess or a cavity that is centrally positioned in said downstream face;at least one ring of extrusion orifice extensions in said recess or cavity in said downstream face through which said extrusion orifices extend;a cover plate sized to fit over said recess or cavity and having openings which mate with said extrusion orifices, said cover plate being attached to said die plate body over said recess or cavity in said downstream face to form said cutting face;said cover plate and said recess or cavity forming and defining a thermally insulating air chamber adjacent said cutting face, said air chamber surrounding said extrusion orifice extensions to insulate said extrusion orifice extensions and provide continuous heating along a length of said extrusion orifices, said insulation provided by said air chamber surrounding said extrusion orifice extensions configured to prevent heat loss of the process melt adjacent the cutting face due to a temperature of the cooling water in the cutting chamber. 35. The assembly as claimed in claim 34, wherein said extrusion orifice extensions are configured as a raised circular ridge continuous and unitary with said die plate body and individual orifice protrusions extending from said raised circular ridge, distal ends of said orifice protrusions being attachedly connected to said cover plate. 36. The assembly as claimed in claim 35, further comprising radial electric heaters positioned in radial slots in said die plate body, said raised circular ridge being configured to channel heat from said electric heaters to said orifice protrusions. 37. The assembly as claimed in claim 36, wherein said cover plate has a counter-bore which conforms to a shape of said extrusion orifice extensions and is sized so that the thermally insulating air chamber follows a contour of the raised circular ridge, said raised circular ridge dividing said air chamber into a generally annular outer section and a generally circular inner section. 38. An underwater pelletizer for extruding and cutting a process melt into pellets comprising: a die plate body with a plurality of extrusion orifices formed therein through which process melt is extruded to exit at a cutting face, said die plate body having a downstream face that includes a center section and a generally circular periphery, said center section of said downstream face having a generally circular cutout formed therein, said circular cutout being inset from and generally concentric with said periphery of said die plate body downstream face and extending across said downstream face center section;a rotary cutter blade assembly in opposed relation to the cutting face on a downstream side of said die plate body, said cutter blade assembly having a hub and at least one cutter blade mounted on said hub and capable of moving in a plane generally parallel to and closely adjacent said cutting face to cut strands of process melt extruded through said orifices into pellets;a water box having a cutting chamber enclosing said cutting face and cutter blade assembly, said water box including a water inlet for introducing cooling water into the cutting chamber and an outlet for discharge of water and pellets entrained in the water;at least one ring of extrusion orifice extensions encasing said extrusion or through which the process melt is carried from said die plate body to said cutting face;a circular cover plate having holes matching said extrusion orifice extensions and sized to mate with and fit over said circular cutout and ends of said extrusion orifice extensions, said cover plate and said cutout together forming and defining a generally circular air chamber inset into the downstream face of the die plate body and closed by said cover plate, said air chamber surrounding said extrusion orifice extensions and thermally insulating said die plate body from said cutting face to provide continuos heating along a length of the orifice extensions and to prevent heat loss from the process melt adjacent the cutting face; andradial electric heaters positioned in radial slots in said die plate body, said die plate body channeling heat from said heaters to said extrusion orifice extensions. 39. The assembly as claimed in claim 38, wherein said air chamber is vented to an atmosphere outside the die plate assembly to prevent pressure build up and/or vacuum formation in said air chamber. 40. The assembly as claimed in claim 38, wherein said extrusion orifice extensions are configured as a raised circular ridge continuous and unitary with said die plate body and include a plurality of individual orifice protrusions extending from said raised circular ridge, distal ends of said orifice protrusions being attachedly connected to said cover plate adjacent said cover plate holes.
