Abstract: In an apparatus for helically slitting a continuous tubular film of synthetic thermoplastic material, a pair of feed rollers for feeding flattened continuous tubular film to a mandrel are mounted at fixed locations in a main frame. A rotary support mounted in the main frame carries the mandrel which consists of spaced apart low-friction bars disposed in a circular array concentric to the axis of rotation of the rotary support. A cutter is adapted to slit the tubular film as it traverses the mandrel. The axis of rotation of the support is aligned with the nip between the feed rollers approximately at the center of their length. A reversing rod and a deflecting or guide roller are connected to the rotary support for guiding the slit film from the mandrel to a winder. The winder has a winding axis aligned with or intersecting the axis of rotation of the rotary support at a right angle. A spreader for opening out the film is disposed between the feed rollers and the mandrel.

Abstract: A single-screw extruder for producing thermoplastic and elastomeric products includes a hollow cylindrical barrel, which is provided with radially inwardly protruding mixing elements, which are adapted to move through recesses formed in one or more helical lands of a screw, which is rotatably mounted in the barrel. To facilitate the assembly of the screw extruder and to permit repair thereof without a need to replace the entire housing, the mixing elements (9) are provided on split rings (9), which are held axially spaced apart by interposed spacing rings, or which are clamped in position in grooves formed in adjacent annular sections of the barrel.

Abstract: Flattening and take-off apparatus for use with a device for providing a blown tubular film. The apparatus includes a flattening device for flattening the tubular film, and a cutting device for cutting one lateral edge of the flattened film. A pair of pinch rollers is provided and is driven to carry the cut and flattened film to an unfolding device, which is defined by a pair of edges that are inclined relative to the direction of movement of the film web, and over which respective ones of the juxtaposed portions of the cut flattened web are adapted to pass to define a single ply web. The pinch rolls include removable spacing rings to prevent the formation of a fold line on the opposite lateral edge from the cut edge of the flattened film. The unfolding device is movable laterally and parallel to the direction of movement of the film.

Abstract: Cooling apparatus for air-cooling tubular plastic film which has been extruded from a film blowing head comprises spaced apart cooling rings, which in the direction of extrusion succeed the annular extrusion die of the film blowing head and are substantially concentric to the axis of the extruded tubular film and have air-guiding surfaces facing the surface of the tubular film and define annular nozzle gaps for delivering cooling air, which flows in contact with said air-guiding surfaces. The air-guiding surfaces are convexly curved in a longitudinal sectional view of the cooling rings. The nozzle gaps are defined by rings which in the direction of flow of the cooling air precede the cooling rings and which are so arranged that the cooling air discharged from said nozzle gaps flows in a direction which is approximately parallel or at an acute angle to the direction of travel of the tubular film.

Abstract: Apparatus for cooling tubular plastic films extruded from a film blowing head. Air cooling means consisting of co-axial pipes extending axially through the film blowing head supply the cooling and inflating air and withdraw the same from the inflated parison. Vertically inner cooling rings are disposed substantially concentrically to the axis of the parison downstream of the annular extrusion die orifice of the blowing head. The inner cooling rings define nozzle gaps and have air guiding surfaces, which face the wall of the parison and are convexly curved in a longitudinal section of the inner cooling rings and during the operation of the apparatus are swept by the cooling air blown out of said nozzle gaps. An outer cooling air jet concentrically surrounds the extruded parison and serves to blow air in a direction which is approximately parallel to the direction of travel of the parison. The inner cooling rings are concentric to the parison.

Abstract: In a blowing head for making tubular films from thermoplastic material, a lateral inlet for supplying molten material opens into a first annular passage having an upper boundary wall, which extends in a plane which is substantially radial with respect to the blowing head. A second annular passage is provided, which is concentric to the first annular passage and leads to a die orifice, from which the tubular film is extruded. The said second annular passage is separated from the first annular passage by a tubular partition, which has a flow guiding surface, which adjoins both annular passages. The axial length of said tubular insert, measured from the upper boundary wall to the flow guiding surface, decreases from the inner end of the inlet to the diametrically opposite line of confluence of the streams of molten material diverging from the inlet in such a manner that all flow paths for the molten material flowing from the inlet to the die orifice are substantially equal in length.

Abstract: Cooling apparatus for tubular plastics film extruded from a film blow head includes an outer cooling ring which surrounds the extruded tubular film and defines an annular nozzle gap with a blowing direction substantially parallel to the wall of the tubular film. Near the end of a cooling section formed by an inner cooling ring beneath the inflated region of tubular film, there is an apertured baffle plate or diaphragm of which the axial projection onto the film bubble covers at least its interior inflated region and, together with the wall of the tubular film, bounds an annular gap.

Abstract: A passage for transferring molten plastic material processed in an extruder contains distributing elements for dividing the molten stream into partial streams and for recombining said partial streams in a different relation to each other. In order to minimize boundary layer faults which result from the distribution of the partial streams, the molten stream is divided into partial streams by at least one annular distributing disc, which is provided on its entrance side with an annular series of openings, and in which adjacent ones of said openings are succeeded by bores which extend radially outwardly and radially inwardly, respectively, so that the molten stream is divided into sectorlike partial streams which are conducted radially inwardly and radially outwardly, respectively, in adjacent bores and are then recombined.

Abstract: The funnel member of a single-screw extruder comprises a housing and a feed screw which passes at least partially axially therethrough and is sealed from the drive shaft by a return feed screwthread covered by a bushing which is fixed with respect to the housing. The feed screw is enveloped by a grooved sleeve having take-in grooves which are parallel to the axis and become shallower in the feeding direction. For charging the material, the funnel member is provided with an eccentric filling aperture tangential to the feed screw. To reduce torque and pressure fluctuations caused in the charged thermoplastic masses by the threads of the screw running past the single aperture, the grooved sleeve (9) is provided with take-in grooves (10, 11) over its entire circumference only in the zone upstream of the filling aperture (4) and, in the region of the filling aperture (4), is provided with take-in grooves (10) only in the part substantially radially opposite to the filling aperture (FIG. 3).

Abstract: A nozzle ring of an extruder for blowing tubular plastics film is divided into cooling sectors provided with adjusting elements. The thicknesses of the blown film are measured over the circumference thereof and a number of film sectors of equal circumferential length corresponding to the number of cooling sectors is established from the measured thicknesses. Assuming that the film sector of maximum or minimum thickness has been extruded in the correct position for the purpose of determining the cooling sector associated with the film sector, the subsequent film sectors are in turn allocated to successive cooling sectors. From the measurements, the mean thickness distributions are determined over the individual film sectors. These values of mean thickness distribution define a measure for the correcting command for the adjusting elements of the cooling sectors that are associated with the respective film sectors.

Abstract: To achieve a substantially uniform thickness of film extruded from or coated by a sheet die, the thicknesses of the film are measured over its width and the film is sub-divided widthwise into imaginary sections of equal length. Each film section is associated with a correcting section of the sheet die. If the thickness measurement reveals a thick or thin portion in a film section, the associated correcting section is cooled or heated, respectively. The mean thickness distributions are determined from the measurements and employed as a correcting signal for setting elements of the individual correcting sections.

Abstract: In an extruder for making blown tubular film, an extrusion nozzle is divided into equally long segments provided with temperature setting elements. The film thickness is measured over the circumference of the film and film sectors of equal cross-sectional area are allocated to the nozzle segments out of which they were extruded. To produce thick film portions, the associated nozzle segments are cooled accordingly and to produce thin portions the associated nozzle segments are heated accordingly.

Abstract: A nozzle ring of an extruder for blowing tubular plastics film is divided into cooling sectors provided with adjusting elements. The thicknesses of the blown film are measured over the circumference thereof and a number of film sectors of equal circumferential length corresponding to the number of cooling sectors is established. Assuming that the film sector of maximum or minimum thickness has been extruded in the correct position for the purpose of determining the cooling sector associated with the film sector, the subsequent film sectors are in turn allocated to successive cooling sectors. The mean thickness distributions are determined from the measurements over the individual film sectors.

Abstract: A nozzle ring of an extruder for blowing tubular plastics film is divided into cooling sectors provided with adjusting elements. The thicknesses of the blown film are measured over the circumference thereof and a number of film sectors of equal circumferential length corresponding to the number of cooling sectors is established from the measured thicknesses. Assuming that the film sector of maximum or minimum thickness has been extruded in the correct position for the purpose of determining the cooling sector associated with the film sector, the subsequent film sectors are in turn allocated to successive cooling sectors. From the measurements, the mean thickness distributions are determined over the individual film sectors. These values of mean thickness distribution define a measure for the correcting command for the adjusting elements of the cooling sectors that are associated with the respective film sectors.

Abstract: A nozzle ring of an extruder for blowing tubular plastics film is divided into correcting sectors provided with adjusting elements. The thicknesses of the blown film are measured over the circumference thereof and a number of film sectors of equal cross-sectional area corresponding to the number of correcting sectors is established from the measured thicknesses. Assuming that the film sector of maximum or minimum thickness has been extruded in the correct position for the purpose of determining the correcting sector associated with the film sector, the subsequent film sectors of equal cross-sectional area are in turn allocated to successive correcting sectors. The throughput and cross-sectional area or temperature of the respective correcting sector is adjusted until the circumferential lengths of the film sectors are equal.

Abstract: In a film blowing plant comprising an extruder for the melt, a film blowhead, calibrating means for the blown tubular film, oscillatory take-off means for the film and a coiler for the flattened film, the output of the plant is set to an optimum figure by a process computer controlling the width and thickness of the film. The height of the line of solidification of the film above the blowhead is measured and, in response to a departure of this height from a given desired value, the output of the extruder is increased or reduced as the case may be.

Abstract: The woven tubing is continuously advanced and is opened and backed from the inside in a certain region, in which plastics material tubing which is larger in diameter than the woven tubing is extruded and oriented around and is forced in a soft condition against the woven tubing and then cooled.

Abstract: Sacks are successively filled and closed in an automatic process by suspending each sack from near the mouth and spreading the side walls apart, filling the sack, allowing it to settle on a support while keeping the side walls taut, bringing the side walls together near the mouth and folding them over onto themselves, welding a closure tape over the folded-over portion and the adjoining unfolded portion of the sack, crimping the unfilled upper part of the sack and gathering it to form a frill, and applying a clamping ring beneath the frill.

Abstract: In a film blowhead for making tubular plastics film, internal cooling air is supplied through a central aperture in the blowhead to superposed cooling air supply rings which support the film on the inside and have outlet apertures facing the film as well as apertures extending axially therethrough for withdrawing the heated cooling air. A central tube is provided to supply the cooling air, the tube being connected to the air supply rings by radial air passages. The annular space between the central tube and the film blowhead and the air supply rings forms an annular passage for withdrawing the heated cooling air.

Abstract: In an apparatus for helically slitting a continuous tubular film of synthetic thermoplastic material, a pair of feed rollers for feeding flattened continuous tubular film to a mandrel are mounted at fixed locations in a main frame. A rotary support mounted in the main frame carries the mandrel which consists of spaced apart low-friction bars disposed in a circular array concentric to the axis of rotation of the rotary support. A cutter is adapted to slit the tubular film as it traverses the mandrel. The axis of rotation of the support is aligned with the nip between the feed rollers approximately at the center of their length. A reversing rod and a deflecting or guide roller are connected to the rotary support for guiding the slit film from the mandrel to a winder. The winder has a winding axis aligned with or intersecting the axis of rotation of the rotary support at a right angle. A spreader for opening out the film is disposed between the feed rollers and the mandrel.