Abstract: A process and apparatus for the finish grinding of cutting blades of a cutting tool head of a granulating device for thermoplastic material in which a grinding wheel is supported for rotation about a vertical axis with a grinding surface of the grinding wheel facing upwardly and the cutting blades of the cutting tool head rest on the grinding surface of the cutting tool head under the weight of the grinding wheel. The cutting tool head is free for vertical movement and is precisely aligned with the axis of rotation of the grinding wheel. The grinding wheel is driven by a motor around a vertical axis to grind the cutting surfaces of the cutting blades and produce precision ground surfaces on the blades which are aligned in a common plane.

Abstract: A granulating device for plastic compounds in which cutting knives of a cutting device face the die plate of a granulating head to form granules of plastic strings extruded from the die plate. The cutting knives are supported on a cutting shaft driven in rotation by a drive shaft of a drive motor. The cutting shaft is rotatably supported in fixed axial position in a housing. In order to obtain a planar parallel and central positioning of the cutting knives relative to the die plate, for example, due to thermal displacement, the housing and drive unit are guided together in a displaceable manner on guide shafts having first ends fixed to the granulating head and opposite ends which are vertically supported for universal pivotable movement in the manner of propped cantilever beams.

Abstract: In pelletizing apparatus, an orifice plate forms plastic strands, the orifice plate having a distributor channel at its inlet side in the form of a grooved annular inlet. A cutting plate is provided with outlet openings which are connected to the distributor channel by inlet channels arranged around the distributor channel in successive adjoining relation. In order to improve the melt flow in the inlet region, the distributor channel has a cross-sectional width in the radial direction that is less than the radial extent of the inlet channels where they are joined to the outlet openings. The longitudinal axes of adjacent inlet channels are arranged at an angle of inclination relative to each other.

Abstract: A process for the manufacture of an orifice plate for pelletizing of plastics in which inserts are inserted into corresponding recesses in the orifice plate, the inserts being formed with blind bores before their insertion into the recesses. The blind bores terminate in proximity to the outer surface of the inserts and after soldering of the inserts into the recesses and hardening of the inserts, the outer surface of the base plate and of the inserts are ground down to expose the blind bores and form a planar outer surface for the orifice plate.

Abstract: A perforated granulating plate construction in which conically tapering inlet channels are connected to several outlet channels, the collective cross-sectional area of the outlet channels being substantially equal to the cross-sectional area at the outlet of the associated inlet channel. The outlet channels form an angle of inclination with respect to the longitudinal axis of the associated inlet channel and the discharge outlets of the outlet channels are arranged in a plane about an axis of symmetry which is coincident with the longitudinal axis of the inlet channel.

Abstract: A perforated plate construction for the underwater granulating of plastic strands comprising a base member with a melt distribution channel and a plurality of inlet channels connected to the melt distribution channel and to extruder nozzles of a cutting plate. The base plate is heated in the region of the inlet channels. Between the base member and the cutting plate is an insulating layer through which the extruder nozzles extend. In order to permit compensation for thermal expansion in the cutting plate without damage to the cutting plate and the insulating layer, the latter is formed as an air gap which is substantially coextensive with the cutting plate in the transverse direction of the extruder nozzles. The cutting plate is supported on the base plate by a plurality of tubular support elements which are separate from each other and freely extended through the air gap.

Abstract: A filter device for a screw extruder for the handling of molten plastic comprising a filter housing having inlet and outlet bores and a slide displaceable in the housing transverse to the direction of the flow of the melt. At least one recess in the slide forms a portion of a melt channel and receives a screen member. In order to obtain uniform distribution of the flow of melt in the filter device and of the pressure forces acting on the filter surface, the recess is formed by an annular milling which is surrounded by a replaceable cylindrical screen member. A flow passage in the slide extends from the melt channel to the outlet bore.

Abstract: A cassette filter for molten plastic comprising a filter screen movable transversely of the melt flow and enclosed between plates in a filter casing of an extruder. The superimposed plates are engaged in a guide passage and the inlet and outlet of the filter casing is sealed by cooling of the melt. The surface of the filter screen is clamped between a tooth-shaped surface of a plate and a cover member which interfits in the profile.

Abstract: A screening apparatus for molten plastic material flowing from an extruder comprising a housing mounted on the extruder and having a feed channel for flow of the plastic material therefrom and a slide member mounted for slidable movement in the housing with a clearance therebetween. The slide member contains replaceable screen elements adapted for being positioned in the path of flow of the plastic material flowing from the extruder to effect screening thereof. In order to seal the clearance between the slide member and the housing to prevent outflow of plastic material therefrom, a flange is mounted on the housing to surround the slide member with a gap therebetween. This permits normal free-sliding movement of the slide member in the housing. The flange contains cooling channels to permit flow of a coolant to cool plastic material in the gap and solidify the plastic material to prevent outflow of plastic material from the gap.

Abstract: A device for granulating plastic strands includes an extruder having a nozzle plate with boreholes arranged in front of a manifold and a starting valve connected thereto, and a cutting device with a knife head arranged centrally in a receiving housing wherein the cutting knives of the knife head rotate in the region of emergence of plastic strands which are acted on radially by a coolant. The cooling is accomplished by providing a cutting plate with cooling boreholes aligned axially with the nozzle boreholes of the nozzle plate. These cooling boreholes extend up to an insulating layer except for a recess which is connected to a coolant feedline for releasing at least one flow cross section of coolant which corresponds to the cooling boreholes.

Abstract: The present invention relates to a nozzle, especially to a nozzle in the form of a perforated plate, for granulating synthetic plastics material, and more particularly for granulating in water.