Center heated die plate for underwater pelletizer
AssigneeGala Industries, Inc.
InventorMichael A. Fridley
Life of this patent
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Abstract
A center heated die plate for an underwater pelletizer radiates heat outwardly to the extrusion orifices and die faces of the die plate thereby maintaining the die plate and extrusion orifices at an elevated temperature to obtain optimum flow of molten polymer through the extrusion orifices. In one embodiment, a centrally located heating plate is mounted in a recess on the upstream face of the die plate inwardly of the nose cone. In a second embodiment, a cylindrical heating coil is placed in a hollow central core of the die plate between the nose cone on the upstream side and an insulation plug or plate on the downstream side. Heating leads extend through a single radial hole in the die plate to provide power to the center heating element.
Claims21
A die plate and heating assembly for a pelletizer, comprising an extrusion die plate having an inner wall that defines a hollow cylindrical center that extends all the way through the die plate from an upstream face to a downstream face thereof, said die plate including a plurality of orifices surrounding and separate from said hollow center through which molten polymer flows from said upstream face to said downstream face and is extruded to exit at said downstream face as a strand cut into pellets by a moving cutting assembly, and a generally cylindrical coil heating element positioned in said hollow center of said die plate in heat exchange relation to said die plate inner wall to retain said inner wall and the extrusion orifices located adjacent and exterior to said inner wall at an elevated temperature and maintain the polymer passing through the orifices in a molten state as the polymer passes through the orifices.
A die plate for extruding polymer strands in an underwater pelletizer which comprises a plurality of extrusion orifices oriented in a circular pattern around a periphery of the die plate and extending from an upstream face of the die plate to a downstream face of the die plate, said die plate having an inner wall that defines a hollow cylindrical area also extending from said upstream face to said downstream face to pass all the way through said die plate, said hollow area being substantially centrally located in said die plate and separated from said orifices by said inner wall, said hollow cylindrical area being configured to receive a generally cylindrical coil heating element positioned in heat exchange relation to said inner wall of said die plate which is located inwardly of the circular pattern of said extrusion orifices to radiate heat outwardly to said extrusion orifices through said inner wall to maintain the polymer in a molten state during passage through said orifices.
A die plate and heater assembly for extruding polymer strands in an underwater pelletizer which comprises an extrusion die plate having a plurality of extrusion orifices oriented in a circular pattern around a periphery of the die plate and extending from an upstream face of the die plate to a downstream face of the die plate, said die plate having a hollow cylindrical area located radially inwardly of and separate from said extrusion orifices and also extending all the way through said die plate from said upstream face to said downstream face, and a cylindrical coil heater positioned in said hollow cylindrical area in said die plate.
Dependencies are inferred from the claim text.