Abstract: An apparatus for controlling extrusion back-pressure in a face cutting apparatus having an extrudate feed means, a die and a cutter is provided. The apparatus consists of a pair of nested dies, one upstream and one downstream, each die having a plurality of areas, each of the areas having a plurality of extrusion orifices. The nested dies are movable relative to another. In one relative position, the orifices of the upstream die exactly aligned with the orifices of the downstream die. Means are provided for relative movement of the dies in response to a change in the pressure adjacent the extrudate delivery end.

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: Apparatus for separating a substantially insoluble liquid from a mixture containing a polymer or polymer mixture. The liquid is a vapor at the usual temperature and pressure of the polymer extrusion operation and is kept in liquid form by providing a high pressure region in the extruder. A liquid outlet is provided upstream of the high pressure region and the liquid is maintained under pressure and taken off as a liquid. The pressure restricting means may be a liquid outlet provided with a pressure control valve, trap or the like.