Abstract: The invention relates to a device (1) for providing a melt, in particular a plastic melt. Said device (1) comprises a feed unit (2) for material components, at least one purification unit (4) for the flowing melt, in particular a rotatable screening disc (5), and at least one sensor unit (17; 18; 19; 20; 21) for detecting one or more process parameters. The operation of the purification unit (4) can be influenced with the aid of said sensor unit, based on the filter-specific process data. The inventive device is configured in such a way that at least the type and dosage of the process materials that are supplied via the feed unit (2) and/or the processing parameters of said process materials can be controlled using the detected (17; 18; 19; 20; 21) process parameters and/or the filter-specific process data.

Abstract: The invention concerns an extruder for producing molted plastic materials from plastic granules available on the market, by heating and mixing granules, with heated single- or double-screw extruders, and for carrying out polycondensation or polymerization using part of a multiple-screw extruder and by means of vacuum chambers for removing the constituents of low molecular weight and/or foaming agents or the like, for obtaining larger molecules and hence a higher viscosity, and for increasing the mechanical strength of plastic materials produced from said molten material. The invention aims at designing said extruder such that the molten material can be processed in thin layers enabling exposure of large surfaces in contact with the vacuum, and hence a molten plastic material ensuring desired levels of degassing and polymerization using simple means.

Abstract: A device for cleaning melt filters which are intended for filtering melts, particularly plastic material melts in extruders, and which include at least one moveable sieve disc with one or more exchangeable sieve inserts, wherein at least one sieve insert is moveable into a flow of cleaning medium within the device in such a way that the sieve insert is located above or below an inlet opening of a cleaning duct. The sieve insert is arranged in the sieve disc at a distance from the surface of the sieve disc which faces the inlet opening.

Abstract: A device for cleaning melt filters which are intended for filtering melts, particularly plastic material melts in extruders, and which include at least one moveable sieve disc with one or more exchangeable sieve inserts, wherein at least one sieve insert is moveable into a flow of cleaning medium within the device in such a way that the sieve insert is located above or below an inlet opening of a cleaning duct. The sieve insert is arranged in the sieve disc at a distance from the surface of the sieve disc which faces the inlet opening.

Abstract: The invention relates to an arrangement for filtering plastic melts. Dirty filter elements (4, 4) can be liberated from collected dirt particles by means of backwashing. The melt (8) used for backwashing is deviated from the main melt flow and can optionally and additionally be impinged upon by conveying elements. Backwash is periodically initiated according to the time and/or the degree of soiling of the filter element to be cleaned. The aim of the invention is to improve the inventive arrangement in such a way that cleaning is optimal according to the degree of soiling of the filter element to be cleaned respectively. A control device (7) is provided which detects the melt volume and/or the flow rate of the backwashing melt during a backwashing procedure.

Abstract: A multipath valve for distributing and/or dividing at least one flow of polymer melt during the manufacture and processing thereof, wherein melt flows through all internal chambers of the valve during all conditions of operation. At least one rotary disc is rotatably mounted on an axle bolt between a front plate and a rear plate which are each provided with openings serving as inlets and outlets for the polymer melt. The rotary disc is provided with circular segment-shaped ducts having a width and end radii corresponding to an inner width of the openings, wherein the ducts have center lines which are located on a reference circle extending through the centers of the openings, and wherein the positions of the ducts are adjustable in accordance with a desired flow direction of the polymer melt.

Abstract: A multipath valve for distributing and/or dividing at least one flow of polymer melt during the manufacture and processing thereof, wherein melt flows through all internal chambers of the valve during all conditions of operation. At least one rotary disc is rotatably mounted on an axle bolt between a front plate and a rear plate which are each provided with openings serving as inlets and outlets for the polymer melt. The rotary disc is provided with circular segment-shaped ducts having a width and end radii corresponding to an inner width of the openings, wherein the ducts have center lines which are located on a reference circle extending through the centers of the openings, and wherein the positions of the ducts are adjustable in accordance with a desired flow direction of the polymer melt.

Abstract: A filter device for filtering plastic melts includes a filter wheel having cavities which are covered by screening elements. A pressure sensor is provided in a melt inflow line upstream of the filter wheel. A pressure sensor is also provided in a melt outflow line downstream of the filter wheel. The pressure sensors measure the pressure drop across the filter. The melt inflow and outflow lines are connected to a melt channel in the filter device, respectively. A melt return line is in connection via a pump and a discharge line with a backflushing slot. The discharge line is connected to an accelerator for increasing pressure in surges. A further melt return/discharge line is connected via a 3-way valve and a return line to the melt inflow line or to a disposal line.

Abstract: A shot piston device for molten plastic material with a force-operated piston guided in a cylinder provided with an inlet and an outlet, wherein valve arrangements ensure that the cylinder is filled during the return stroke of the piston and the cylinder content is discharged during the work stroke of the piston. The piston is fixedly connected by a drive bolt to a differential piston arranged upstream or in front of the piston. At least in its rearward extreme position, the differential piston covers and closes the outlet arranged in the corresponding differential cylinder. The circumference of the piston has at least one groove located underneath the inlet and extending from the end face of the piston facing the differential piston. The length of the groove is shorter than the length of the piston. A closing ring is arranged so as to be axially slidable on a cylindrical portion of the drive bolt arranged in front of the end face of the piston facing the differential piston.

Abstract: The seals between the plates and a swingable or slidable sieve insert carrier can be hollow to receive a substance having a greater coefficient of thermal expansion than the metal shell of the seal so that the pressing force is generated by expansion of the substance.

Abstract: A filter for a synthetic resin melt has a housing formed from two blocks through which a melt channel for the passage of the plastics melt passes. A screen plate is rotatably mounted to intrude between the blocks and a plurality of recesses are distributed in a circular pattern around the periphery of the screen plate so that rotation can bring two of the recesses in to line with the channel. A plurality of filter elements are accommodated, one each in each recess, so that the plastic melt must pass through the filters in the recesses in line with the channel. To support the filter elements against melt pressure a stationary perforated plate is located in the channel immediately adjacent and downstream of the screen plate. By rotating the screen plate exhausted filter elements can be readily replaced. The filter elements are made of woven wire cloth and may be dished to prevent distortion of the mesh.

Abstract: An inlet plate is normally connected to an extruder and formed with an inlet port for supplying a molten synthetic resin under pressure to the port and an outlet plate is normally connected to or part of a mold and is formed with an outlet port in line with and confronting the inlet port for receiving the molten synthetic resin. A movable filter support engageable snugly between the plates at the ports thereof is formed with at least two laterally offset cavities each having an inlet side against the inlet plate and an outlet side against the outlet plate. This support element can be displaced between at least two respective positions in each of which one of the cavities is aligned between the ports for flow through the one cavity therebetween. A respective filter unit in each of the cavities has a plurality of separate cells each having an outside exposed to flow from one of the ports and an inside exposed to the other of the ports.

Abstract: A filter assembly used in combination with an extruder producing a stream of pressurized molten plastic has an inlet plate formed with a Y-shaped inlet passage having a substantially circular-section upstream end adapted to receive the stream of pressurized molten plastic from the extruder. The inlet passage branches downstream of its upstream end and has a pair of downstream ends opening at substantially circular downstream ports. An outlet plate fixed immediately downstream of the inlet plate is formed with a Y-shaped outlet passage having a substantially circular-section downstream end. The outlet passage is branched symmetrically to the inlet passage upstream of its downstream end and has a pair of upstream ends opening at substantially circular upstream ports aligned with the downstream ports. A rotatable filter disk engaged between the plates is formed with a circularly annular array of substantially circular-section throughgoing holes each defining a respective substantially circular seat.

Abstract: A filter assembly used in combination with an extruder producing a stream of pressurized molten plastic has an inlet plate formed with a Y-shaped inlet passage having a substantially circular-section upstream end adapted to receive the stream of pressurized molten plastic from the extruder, The inlet passage branches downstream of its upstream end and has a pair of downstream ends opening at substantially circular downstream ports. An outlet plate fixed immediately downstream of the inlet plate is formed with a Y-shaped outlet passage having a substantially circular-section downstream end, The outlet passage is branched symmetrically to the inlet passage upstream of its downstream end and has a pair of upstream ends opening at substantially circular upstream ports aligned with the downstream ports.

Abstract: A sieve arrangement for cleaning synthetic plastic melts of a high pressure press has a housing having a throughflow opening which is arranged to form a part of a flow passage of a high pressure press, a disc provided with a plurality of perforations and movable in the housing so that at least one of the perforations is always in the region of the throughflow opening and at least one of the perforations is always outside the housing, a plurality of sieve discs arranged inside the perforations, a blockable spraying passage provided at the side of the throughflow opening which is located behind the disc as considered in a flow direction, a slot-shaped spraying nozzle associated with the perforation located away outside the throughflow opening and inside the housing so that the spraying passage opens into the spraying nozzle, an outlet passage provided in the housing at a side of the disc which is opposite to the spraying nozzle.

Abstract: A screening device for a melt of plastic material includes a housing provided with a throughflow boring forming a part of a high pressure plastic press. A screen plate is movable transversely across the boring and includes a series of screening openings arranged at the level of the throughflow boring and being separated one from each other by an narrow web. To minimize the formation of pressure gradients in the throughflow boring when a new screening opening is entering the boring, each web has at its interface with the housing a narrow overflow slot which sets up a gradual connection for an inflow current of the melt during the entry of a new evacuated opening into the region of the throughflow boring.

Abstract: A sieve device for cleaning plastic melts in a high-pressure press consists of a known plate-like housing. The housing has a flowthrough bore that constitutes part of the flow channel of the press. The housing also has a sieve disk positioned in the flowthrough bore. A sieve-cleaning mechanism rests against the sieve disk. The mechanism consists of a plate, which has several perforations and which projects to some extent out of the housing. It is mounted upstream of the disk inside the housing and can move in such a way that at least one perforation is always in the flow channel and at least one perforation is always outside the housing. Contamination on the upstream side of a disk is removed by shifting the perforation being employed at a given moment out of the housing.

Abstract: Sieve device for cleaning molten plastics in conjunction with a high-pressure press and consisting of a housing with a flow-through bore that constitutes part of the flow channel of the high-pressure press and of a plate or disk that can be displaced or rotated in the housing and that has several perforations or sieve chambers, at least one of which is always in the vicinity of the flow channel and at least one of which is always outside the housing, whereby either a sieve disk is always positioned inside the flow channel or sieve disks are positioned inside the perforations. At least one perforation is always inside the housing but outside the flow channel and can be evacuated before entering the flow channel by a suctioning-out pump or similar device. The sieve chambers are all separated from one another by curved webs, with the surface of one web equal to about 10% or less of the overall surface of one sieve chamber.

Abstract: A ring nozzle for use with an extruder to continuously form a synthetic-resin tube has a substantially stationary back nozzle part having an axially forwardly directed front face and formed with an axially centered passage opening at the face. This part is typically bolted over the outlet of the extruder. An axially centered core rod is substantially fixed in the passage and extends axially forward past the front face. This rod is also fixed in the extruder so that same can emit a hot and thick tubular strand of a plastified synthetic resin. An annular and movable front nozzle part fits with spacing around the core forward of the front face and forms therewith an axially centered and forwardly open annular gap. The thick tubular strand formed by the extruder becomes a thin-walled strand that emerges from the annular gap.

Abstract: This invention relates to a biaxially stretched and longitudinally afterstretched thin-walled tubular film of polyethylene terephthalate having a tensile stress of 40 to 60 kg/mm.sup.2 and a tear resistance of 40 to 70 kg/mm.sup.2 in the longitudinal direction, and an elongation at break of 350 to 800% in the transverse direction. The invention also relates to a process for the production of the film.