Abstract: An underwater pelletizer including a die plate, a cutting chamber housing having a cutting chamber and a rotatably drivable cutter head, which is arranged in the cutting chamber for dividing melt strands output from the die plate into pellets. The cutting chamber is flushed through by process water which can be introduced through at least one inlet into the cutting chamber and, together with the cut pellets, can be discharged from the cutting chamber via an outlet. A plurality of flow channels and/or chambers are provided in the cutting chamber housing for generating different process water streams, which include at least one co-rotating flow path passing through at least one cutter head channel through the rotating cutter head, as well as at least one flow path which does not co-rotate and which leads from a fixed inlet into the cutting chamber.

Abstract: A die plate is provided for an underwater pelletizer. The die plate includes a die plate body and a solid face plate. The downstream face of the die plate body has a plurality of insulation holes drilled therein that reduce the surface area contact between the die plate body and the solid face plate that is secured to the downstream face of the die plate body to form the cutting surface. In addition, a circular groove is preferably milled into the downstream face of the die plate body. The groove is concentric with the outer perimeter of the die plate body and creates an outer ring and a center boss. The outer downstream surface of the boss is flush with the outer downstream surface of the outer ring so that the boss and ring together form the downstream face of the die plate body for supporting the solid face plate. The insulation holes and groove are filled with a non-reactive atmosphere such as nitrogen, inert gas(es), a vacuum or a partial vacuum.

Abstract: A system that enables a cutter head to pivot for improved alignment with a cutting face or die is disclosed. The system includes a cutter hub and a driveshaft hub mated with a plurality of round, spherical, or ovoid surfaces to enable the cutter hub to pivot with respect to the driveshaft hub. The system can include a plurality of alignment pins with spherical surfaces to transfer torque from the driveshaft hub to the cutter hub. The system can also include a cutter head, which can include a plurality of cutting blades. The system can be used in cutting machinery, such as a pelletizer, where alignment of the cutting head and the cutting die (or other cutting surface) is desirable.

Abstract: Described herein are extrusion processes to produce hollow pellets. Also disclosed are pelletizer devices that can be used to produce the hollow pellets. The processes and devices make use of an extrusion die having a die orifice and an insert that is placed in the die orifice to produce the hollow pellets.

Abstract: A die plate is provided for an underwater pelletizer. The die plate includes a die plate body and a solid face plate. The downstream face of the die plate body has a plurality of insulation holes drilled therein that reduce the surface area contact between the die plate body and the solid face plate that is secured to the downstream face of the die plate body to form the cutting surface. In addition, a circular groove is preferably milled into the downstream face of the die plate body. The groove is concentric with the outer perimeter of the die plate body and creates an outer ring and a center boss. The outer downstream surface of the boss is flush with the outer downstream surface of the outer ring so that the boss and ring together form the downstream face of the die plate body for supporting the solid face plate. The insulation holes and groove are filled with a non-reactive atmosphere such as nitrogen, inert gas(es), a vacuum or a partial vacuum.

Abstract: A system that enables a cutter head to pivot for improved alignment with a cutting face or die is disclosed. The system includes a cutter hub and a driveshaft hub mated with a plurality of round, spherical, or ovoid surfaces to enable the cutter hub to pivot with respect to the driveshaft hub. The system can include a plurality of alignment pins with spherical surfaces to transfer torque from the driveshaft hub to the cutter hub. The system can also include a cutter head, which can include a plurality of cutting blades. The system can be used in cutting machinery, such as a pelletizer, where alignment of the cutting head and the cutting die (or other cutting surface) is desirable.

Abstract: Described herein are extrusion processes to produce hollow pellets. Also disclosed are pelletizer devices that can be used to produce the hollow pellets. The processes and devices make use of an extrusion die having a die orifice and an insert that is placed in the die orifice to produce the hollow pellets.

Abstract: An insulated die plate assembly for use in underwater pelletizing and other granulation processes includes a thin, continuous air chamber formed across the plate assembly generally parallel to the die face such that the heated upstream portion of the die plate assembly is thermally insulated from the downstream portion. The air chamber is atmospherically equilibrated by venting the air chamber to the atmosphere. The plurality of extrusion orifices, either individually or in groups, are formed in extrusion orifice extensions that extend through the insulation chamber so that the process melt to be granulated can pass therethrough. The orifice extensions and the components forming the air chamber around the orifice extensions channel heat along said extensions to maintain the process melt therein at a desired temperature, to help rigidify the die plate assembly and to better seal the air chamber.

Abstract: An insulated die plate assembly for use in underwater pelletizing and other granulation processes includes a thin, continuous air chamber formed across the plate assembly generally parallel to the die face such that the heated upstream portion of the die plate assembly is thermally insulated from the downstream portion. The air chamber is atmospherically equilibrated by venting the air chamber to the atmosphere. The plurality of extrusion orifices, either individually or in groups, are formed in extrusion orifice extensions that extend through the insulation chamber so that the process melt to be granulated can pass therethrough. The orifice extensions and the components forming the air chamber around the orifice extensions channel heat along said extensions to maintain the process melt therein at a desired temperature, to help rigidify the die plate assembly and to better seal the air chamber.

Abstract: An insulated die plate assembly for use in underwater pelletizing and other granulation processes includes a thin, continuous air chamber formed across the plate assembly generally parallel to the die face such that the heated upstream portion of the die plate assembly is thermally insulated from the downstream portion. The air chamber is atmospherically equilibrated by venting the air chamber to the atmosphere. The plurality of extrusion orifices, either individually or in groups, are formed in extrusion orifice extensions that extend through the insulation chamber so that the process melt to be granulated can pass therethrough. The orifice extensions and the components forming the air chamber around the orifice extensions channel heat along said extensions to maintain the process melt therein at a desired temperature, to help rigidify the die plate assembly and to better seal the air chamber.

Abstract: A cutter hub for an underfluid pelletizer in which pelletizable material such as molten polymer is extruded as strands through orifices in a die plate. The cutter hub has a plurality of cutter blades integral therewith and is made of a single solid one-piece construction of hub and blades. The cutter hub is rotatably driven and moves along the face of the die plate so that the blades cut the extruded strands into pellets. The cutter hub preferably includes self-aligning structure.

Abstract: An insulated die plate assembly for use in underwater pelletizing and other granulation processes includes a thin, continuous air chamber formed across the plate assembly generally parallel to the die face such that the heated upstream portion of the die plate assembly is thermally insulated from the downstream portion. The air chamber is atmospherically equilibrated by venting the air chamber to the atmosphere. The plurality of extrusion orifices, either individually or in groups, are formed in extrusion orifice extensions that extend through the insulation chamber so that the process melt to be granulated can pass therethrough. The orifice extensions and the components forming the air chamber around the orifice extensions are specially configured to channel heat along said extensions to maintain the process melt therein at a desired temperature, to help rigidify the die plate assembly and to better seal the air chamber.

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 cylindrical heating coil is placed in a hollow central core of the die plate and a plurality of peripheral heating elements are inserted in radial recesses distributed around an outer perimeter of the die plate to create an inner heat zone and an outer heat zone which are separately controllable.

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.

Abstract: A cutter hub and blade assembly for an underwater pelletizer in which molten polymer is extruded as strands through orifices in a die plate. The cutter hub is rotatably driven and includes cutter blades mounted at a steep angle on the cutter hub and move along the face of the die plate to cut the extruded strands into pellets. The cutter blade support angle on the cutter arms is 60°-79°, preferably about 72° to about 76° and most preferably about 75°. The blade cutting edge is beveled or angled at about 40° to about 50° and preferably about 45° to the opposed planar surfaces of the blade. The included angle between the blade cutting edge and the die face is at least about 20°. The inclination of the cutter blade support angle in combination with the blade cutting edge angle in accordance with the invention provides a clean cut of the pellets and enables faster blade grinding when seating new blades to the die face.

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 cylindrical heating coil is placed in a hollow central core of the die plate and a plurality of peripheral heating elements are inserted in radial recesses distributed around an outer perimeter of the die plate to create an inner heat zone and an outer heat zone which are separately controllable.

Abstract: A cutter hub and blade assembly for cutting polymer strands extruded from a die face in a pelletizer has cutter blades mounted on the cutter hub at a steep angle. The blades are beveled along a portion of their leading edge to form a blunt cutting edge or surface to the blades which is generally perpendicular to the die face. By beveling the leading edge of a blade supported at a steep angle to form a blunt cutting edge, the bottom surface area of the blade in contact with the die face can be significantly reduced. The reduced contact area provides several advantages including a clean cut of the pellets and a faster blade grinding when seating the blades to the die face.

Abstract: A cutter hub and blade assembly for cutting polymer strands extruded from a die face in a pelletizer has cutter blades mounted on the cutter hub at a steep angle. The blades are beveled along a portion of their leading edge to form a blunt cutting edge or surface to the blades which is generally perpendicular to the die face. By beveling the leading edge of a blade supported at a steep angle to form a blunt cutting edge, the bottom surface area of the blade in contact with the die face can be significantly reduced. The reduced contact area provides several advantages including a clean cut of the pellets and a faster blade grinding when seating the blades to the die face.

Abstract: A two-piece water box assembly includes a water box main body and an inline adapter ring. The water box main body and inline adapter ring define the water box cutting chamber, with the inline adapter ring being positioned between the water box main body and the die plate. The adapter ring is fastened through the die plate to the extruder inlet housing with a first plurality of fastening elements. The water box main body is also coupled to the extruder inlet housing, through apertures in the die plate and inline adapter ring, by a second plurality of fastening elements, preferably less in number than the first plurality of fastening elements. When access to the cutter hub or cutting chamber is necessary for cleaning or otherwise, the water box main body can be removed easily by unfastening the second fastening elements only, while the inline adapter ring remains fixed to the die plate and extruder inlet housing, thus maintaining the seal therewith and the die plate insulation gasket.

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.