Abstract: A throttle for the adjustment of the pressure of plastic material in screw extruders in which the throttle is a cylindrical plunger submerged in the melt flow in a melt channel. In order to eliminate dead spaces downstream of the throttle, the plunger is arranged in a symmetrical and displaceable manner in a rectangular melt channel and one or more through holes are provided in the plunger in the flow direction in the submerged region of the plunger.

Abstract: A screw-type extruder has a housing and at least one screw which is rotatably arranged in a bore in the housing and which conveys material while melting or plasticizing in a conveying direction to a discharge channel, a starting valve and a throttle for generating a back pressure on the molten or plasticized material being arranged in the area of the discharge channel. In order to avoid long flow paths of the molten or plasticized material via the throttle and starting valve, there is provided a starting valve/throttle unit having a starting valve and throttle body which is displaceable at right angles to the conveying direction out of a starting position into a throttling position.

Abstract: Apparatus for granulating plastic materials which comprises a housing adapted for connection to a granulating hood and including a knife shaft supporting a knife head having cutting knives proximate a perforated plate of an extruder. The knife shaft is mounted for axial displacement by a bearing sleeve which can be actuated by a hydraulic cylinder unit. In order to operate the cutting knives at an adjustable distance from the perforated plate or with constant pressing force, the bearing sleeve is displaceably supported in the housing in a bore which receives the knife shaft, and one end of the bearing sleeve bears against a compression spring which in turn bears against the housing to oppose advance of the knife shaft towards the perforated plate.