Abstract: An apparatus for producing thick slabs of thermoplastic synthetic-resin material comprises a pair of extruders each extruding a half-slab strand to a respective roller assembly, the roller assemblies having final rollers which form a consolidation nip between them in which the two half slabs are bonded together. Preferably the half slabs and the roller assemblies are mirror symmetrically constructed and the half slabs can be formed with longitudinal compartments which can be filled with a foamed synthetic-resin material.

Abstract: A nozzle assembly has an upstream part which transforms a solid thermoplastic-resin strand into an upstream tube section which is centered on an axis and flows axially. Formations inside this upstream part impart rotation about the axis to at least a portion of the material of the upstream tube section. This upstream tube section is then deflected by a distributor radially outwardly and then forced through a plurality of generally angularly equispaced radially extending throttle passages in a throttle ring. The individual solid streams issuing from this throttle ring are united into a downstream tube section that is passed axially through a downstream nozzle part which is also provided with formations that impart rotation about the axis to at least a portion of the material of the downstream tube section. Eventually the tube issues from the downstream end of the downstream nozzle part as a large-diameter tube suitable for blow molding.

Abstract: An apparatus for the cooling, straightening and calibration of a plate-shaped synthetic-resin strand, e.g. of thermoplastic material extruded from a broad-slot nozzle comprises a plurality of straightening rollers on respective stands, the rollers of each stand engaging opposite surfaces of the strand. The rollers are provided with cooling and heating means to ensure homogeneous temperature distribution throughout the strand passing between the pairs of rollers which can be aligned with one another or can be offset from one another. On at least one of the stands the rollers are displaceable alternately parallel to the path of the strand by corresponding oscillating drive.

Abstract: A coupling circuit for the feedback loops of foil-thickness control circuit, a calibrator height-adjusting control circuit, a calibrator diameter-setting control circuit and a balloon-filling control circuit interlocks the control circuits and shifts the responses thereof upon start-up of a film or foil blowing apparatus. The latter also includes the usual blowing heads, connected to a worm extruder, the calibrating basket, the balloon-flattening device, the drawing rollers and the winding device which rolls up the flattened web of blown film.

Abstract: A metering pump whose speed is controlled in accordance with product data is provided between an extrusion press and the extrusion die. The speed of the worm is controlled by a pressure/speed regulator and the temperature at the outlet side of the press is maintained constant within .+-.10.degree. C.

Abstract: Sheets, strips or filaments of thermoplastic resin are produced by one or more extruders working into a remote shaping die that is movably juxtaposed with a cooling drum around which the hot product issuing from the die mouth is to be wound, the die being connected with the extruder or extruders via one or more flexible ducts having heating elements embedded in their walls. Each duct may comprise an inner hose of Teflon, an outer envelope of reinforced silicone rubber and various intermediate layers including a heating layer in the form of a wire coil or mesh and a surrounding heat barrier of asbestos.

Abstract: An apparatus for the extrusion of tubular bodies of synthetic-resin material and especially large-diameter pipes, in which the die for forming the tube is connected to an extrusion press and includes an outer member and an inner member between which the material is forced. On the outer member there is provided a calibrating sleeve and the die carries a radioactive thickness-measuring means.

Abstract: The synthetic-resin tube emerging from an extrusion die is internally sealed by a pair of sealing members having inflatable peripheries and connected to flexible members running back through the die so that one of the seals can be drawn toward the die while the other is entrained with the tube away from the latter and vice versa.

Abstract: A synthetic-resin tube as it emerges longitudinally from an extruder is passed over a two-part mandrel. A coolant such as water issuing from the upstream part of the mandrel passes axially downstream around the mandrel and is drawn into openings at the downstream part of the mandrel to draw the tube inwardly by suction toward the mandrel and impart to this tube the exact shape of the mandrel. Either or both of these parts may be formed as a longitudinal succession of transverse vanes having external peripheral shapes corresponding to the desired internal shape to be imparted to the tube. It is also possible to form either or both of the parts of the mandrel as a hollow cylindrical body formed with intake or output openings constituted as slits running either in the direction of travel or transverse thereto.

Abstract: An extruder is operated continuously to produce a plastically deformable strand that is pulled through a calibrating die and a cooling by a withdrawal arrangement downstream of the die in the bath. A sensor detects the volume of the strand between the tool and the extruder and controls the withdrawal rate in accordance with the volume of the strand between the tool and the extruder so as to produce an accurately calibrated extrusion. The sensor may engage the strand at the bank formed immediately upstream of the mouth of the calibrating die or may be upstream therefrom and detect the hang or droop of the strand between the die and the extruder.

Abstract: An apparatus for calibrating synthetic-resin tubing issuing continuously from a nozzle comprises an inner relatively long tube extending downstream from the nozzle and connected to an exhaust pump. A shorter outer tube surrounds this inner tube and defines therewith an annular chamber. A plurality of axially spaced disks of like outside diameter are carried on this outer tube and the compartments defined between these disks communicate with the annular chamber through holes formed through the outer tube. These holes as well as axially throughgoing holes in the disks are of adjustable flow cross section for aerodynamically balancing the air flow within the tubing as it emerges from the extruder. Thus air injected into the tubing adjacent the nozzle can flow up around the disks, between the compartments of the disks, and from each of these compartments into the annular chamber, to be eventually sucked out through the relatively long tube at the center of the apparatus.

Abstract: A composite foil or laminate of two synthetic-resin foils having mutually transverse main stretch directions (orientations) is formed by bonding the foils together after they have been incised in rows of spaced-apart incisions extending in the main stretch direction of each foil. Successive alternating rows along the foil have incisions offset along the rows from one another.

Abstract: Several thermoplastic tubes to be bonded to one another are jointly extruded through concentric annular orifices while cool air is blown from annular Venturi nozzles in concentric streams past the outer surface of the outermost tube and past the inner surface of the innermost tube to accelerate their solidification. The inter-tube space or spaces can be inflated by similar air streams blown at least in part along their confronting tube surfaces. The return of the injected air from the innermost and inter-tube spaces takes place through conduits disposed midway between the nozzles.