Abstract: In a face cutting apparatus having an extrudate feed means with an extrudate delivery end, a die plate and a cutter, an apparatus and method for controlling extrusion back pressure includes a die having a plurality of extrusion orifices through which a heat plastified material is adapted to be extruded, having a varying orifice density along the length of the die, a pressure sensing device for sensing the pressure adjacent the delivery end and an apparatus for moving the die relative to the delivery end in response to changes in the pressure adjacent the delivery end to align a die area of differing orifice density with the delivery end in order to adjust the flow rate of heat plastified material through the die and the extrusion back pressure.

Abstract: An apparatus and method for extracting water from rubber is provided. The rubber is screw conveyed in a twin screw extruder and alternately compressed between the forward side of the screw conveying threads, the inner extruder chamber wall and the wedge-shaped screw shaft. Water is squeezed out of the compressed rubber particles and drained off. The extruder chamber wall preferably has longitudinal grooves to impede the revolving movement of the rubber particles and to further squeeze the water from the rubber particles.

Abstract: Plastic materials are dewatered in an extruder by applying heat and pressure and venting out vaporized water; before the plastic is extruded through the die orifice a gas is injected under high pressure into the plastic and this causes gas explosions when the plastic is released through the die orifices. The particles produced have micropores which provide improved workability, and form bales of controllable density.

Abstract: The cutter used with a cylindrically shaped die plate means on a thermoplastic extruder is rotatable about the axis of the die plate and has a plurality of radially projecting blades that extend longitudinally and sweep across the downstream face of the die plate means as the cutter rotates severing extruded heat-plastified material into pellets. The blades form continuous longitudinal channels within which the pellets collect as the cutter rotates. The cutter is enclosed to permit pellet treatment fluid to flow longitudinally over the cutter and flush the pellets from the channels as soon as the pellets are severed. The die plate means comprises a pair of nested die plates mounted for selective positioning relative to one another. In one relative position, the orifices in the plates are essentially aligned to offer minimum constriction to the extrusion of heat-plastified material through the orifices.