Abstract: A corrugator and mold management apparatus and methods for continuously forming transverse corrugations and other shapes in a tubular polymer melt parison formed by an extrusion die employs a plurality of molds that interlock when mated. Each mold has common outside dimensions and a pair of open linear bearings that provide the mold axis and maintain alignment of the molds parallel to and in the same horizontal plane as the axis of the extrusion die. The molds are moved axially along supported rails by bi-directional linear actuating modules and between the pairs of supported rails by lateral transport units. Inner supported rails define the mold tunnel and outer supported rails provide an outer path to move molds upstream back toward the extrusion die. The lateral transport units include extensible rails that facilitate the transfer of molds to and from the mold tunnel and the outer return paths. Delivery units remove from and introduce molds from a plurality of parking stations.

Abstract: There is provided a plastic extrusion sizing tube having a cylinder with a split along its length to allow for radial expansion and reduction of the sizing tube. The cylinder has holes to allow an extrusion within the cylinder to be drawn to the cylinder by a vacuum outside the cylinder. The cylinder also has extensions on opposite sides of the split with an adjustment screw connecting the extensions. The diameter of the cylinder can be expanded or reduced when the adjustment screw is turned in respective directions. A set screw can be connected to one of the extensions. The diameter of the cylinder can be expanded or reduced when the set screw is turned in respective directions. The diameter of the cylinder can be locked in a desired position when the adjustment screw and the set screw are turned in the same direction. The adjustment screw and the set screw can be located in a flange at one end of the cylinder. The holes in the cylinder can be slots.

Abstract: The invention concerns a continuous manufacturing method which consists in producing a blank (E) by extrusion, bringing said blank to a temperature for molecular orientation, passing said blank around a radial expansion mandrel (12); gauging and cooling while subjecting the blank to axial traction. The radial expansion produced on the mandrel (12) is partial so that the internal diameter (B) of the blank (E), when it leaves the mandrel, is less than the nominal internal diameter (D) of the finished tube; performing an additional radial expansion of the blank, up to its nominal diameter, by internal fluid pressure. In permanent operating conditions, the inner surface of the blank (E) is no longer in contact with the mandrel (12).

Abstract: A ribbed pipe molding apparatus has a die with a plastic flow passage which carries molten plastic from an extruder to a mold for making the ribbed pipe. The plastic flow passage has a downstream flow region which exits at an acute angle through the external surface of the die. The inner wall of the end region which locates downstream of the outer wall of the flow passage in the downstream flow region of the passage has a transition wall part which is also inclined relative to the exterior surface of the die but which is sloped at a angle less than the main part of the downstream flow region of the passage. The transition wall part of the inner wall shapes the mouth of the passage so as to produce a wedging of the plastic flowing through the passage into the mold for extremely efficient production of the ribs on the pipe.

Abstract: An external stabilizer or guide cage for plastic film extrusion has an upper frame comprised of a ring and structure for rotatably supporting the ring. A lower frame is suspended from the ring of the upper frame, and is positioned such that the lower frame surrounds the extruded tube. The lower frame can employ one or several banks of guide arms that keep the tube aligned axially as the tube is drawn upwards. The arms on the lower frame define an iris aperture, or a stack of iris apertures. The arms include channels for coolant flow. Heat transfers from the film to the guide arm. The upper frame includes a drive for rotating the ring and the lower frame of the guide cage over a predetermined arc, e.g., 60 degrees, to compensate for gauge variations in the film.

Abstract: A half-mold for a corrugator for making pipes with transverse ribs. The half-mold comprises two sides located spaced apart from each other and a semi-cylindrical base surface linking the two sides. Directly mounted forming elements bent in the shape of a semicircle which define the outer surface of the pipe with transverse ribs are removably fixed on the base surface. The directly mounted forming elements bent in the shape of a semicircle are removably fixed with fixing elements on the half-mold.

Abstract: The invention relates to a shaping apparatus for an extrusion system with at least one calibration die having a plurality of calibration units (31) disposed one after the other, having a calibration orifice (38) with a plurality of shaping surfaces (39 to 42) which come into contact with an article (6) fed therethrough, and end faces (43) spaced apart from one another with side faces (45 to 48) extending between them. At least one cavity is provided between at least two immediately adjacent calibration units (31). The calibration die is provided with means for dispersing heat. The calibration orifice (38) is provided with at least one continuous circulation passage (67) around a predominant part of and immediately adjacent to its circumference, having a separate inlet and outlet line (68, 69).

Abstract: The present invention provides an apparatus and method for manufacturing polymeric thin-walled tubular members, which are well-suited for use as vascular grafts. The apparatus of the present invention enables extrusion of a tubular member having an extremely thin wall thickness so as to facilitate passage through tortuous vascular passageways. The apparatus achieves uniform wall thickness in a tubular member by establishing and maintaining axial alignment of a ram having a concentrically disposed guide rod therein with a die supported in concentric relation to the guide rod.

Abstract: An internal bubble cooling air control system in a blown film apparatus has sensors arranged to increase response time and reduce interference, and includes a high speed valve for fast actuation of air flow from a controller in response to signals received from the sensors.

Abstract: A forming structure for use in an apparatus for making formed polymeric film. The forming structure comprises a first portion comprising a network of interconnecting members defining apertures, the apertures being spaced in a pattern defining a first percent open area, a second portion being solid and having no apertures and zero percent open area; and a third portion being a transition between and joining the first and second portions, the transition portion exhibiting a second percent open area, the second percent open area of the third portion being less than the first percent open area of first portion.

Abstract: The invention relates to a film tube (10) based on cellulose which is produced by extruding an aqueous cellulose-N-methyl-morpholine-N-oxide (NMMO) solution through a ring nozzle (21) onto a lining (3). The film tube (10) is manufactured by means of a vertically descending spinning in a spinning vat (12) in which a spinning bath (11) is located. The film tube (10) which is submerged in the spinning bath (11) passes through an air gap (9) between the underside of a nozzle block (7) and the upper surface of the spinning bath (11) and, internally, is pressurized, supported and slightly stretched in a transversal manner by compressed air. The film tube (10) is filled with an inner bath solution (31) via a supply tube (18). An idle roller (13) is situated near the bottom of the spinning vat (12) in order to guide the film tube (10) around and, afterwards, out of the spinning vat (12) in an upward sloping manner. The film tube is laid flat along a contact section (27) of the idle roller (13).

Abstract: The invention relates to a method for producing a large-volume cup-shaped or tub-shaped container made of a synthetic thermoplastic material, whereby a compact plastic, flexible hose-type preform (6) is extruded to obtain a given length and the container (1) is subsequently shaped. In order to carry out said operations with the aid of extremely simple extrusion devices and moulds, thc extruded preform (6) is expanded to a given size and a core (2) is moved upwards into the expanded preform (6). The lower, open end of the expanded preform (6) is then clamped against the core (2) to provide a seal and the preform is shaped by air in order to form a container.

Abstract: An apparatus for cooling and calibrating and extruded plastic profile (2) is described, with a cooling tank (4) which receives a cooling liquid (12) and can be charged with a pressure below atmospheric, and with at least one calibrating device (5) arranged within the cooling tank (4) for the plastic profile (2) pulled through the cooling tank (4), with the calibrating device (5) being composed of individual parts extending in the direction of passage of the plastic profile (2). In order in to provide advantageous construction conditions it is proposed that the parts of the calibrating device (5) form calibrating elements (8) which are distributed over the circumference of the plastic profile (2) by leaving out gaps (15) for the passage of cooling liquid.

Abstract: An apparatus for the manufacture of profiled plastic pipes comprises a machine bed (1) that half shells (2, 2′) are guided on, forming a molding path (9). A driving pinion (17) is provided above the molding path (9). At least one lower driving pinion (41) is provided on the machine bed (1) along the molding path (9). A lower indentation (39, 39′) is formed in the area of the lower side (30, 30′) of the half shells (2, 2′), with the at least one lower driving pinion (41, 41′) engaging therewith.

Abstract: An air turning bar for a take-off device for plastic films has a hollow cylindrical body having a depression in the region of the bar around which the film is wrapped. The remaining region of the bar is circular cylindrical. Air outlet openings are provided within the depression. Narrow circular cylindrical strips adjoin the ends of the depression which are provided in the longitudinal direction of the air turning bar.

Abstract: A film is extruded from plastic material by an extruder. The film is orientated after extrusion. Material is mixed into the plastic so that when the plastic film is stretched, cavitation bubbles are formed in the material particles mixed into the plastic. During the orientation, gas is arranged to the plastic film under high pressure so that the gas diffuses in the cavitation bubbles and causes overpressure in them. Thus, it is possible to make a thin foamed film with a foaming degree over 70%.

Abstract: Described is an apparatus for producing double-walled corrugated pipes (72) comprising an extrusion nozzle (12) and a cooling mandrel (14) which protrude into a molding passage (16) formed by corrugator molding jaws (18, 20). The extrusion nozzle (12) has a first annular nozzle opening (34) for delivering an outer shell (62) and a second annular nozzle opening (40) for delivering an inner shell (64). The outer shell (62) delivered from the first annular nozzle opening (34) is sucked in the molding passage (16) by means of a vacuum against the corrugated transversely ribbed inner surface (66) of the corrugator molding jaws (18, 20).

Abstract: This invention relates to methods and apparatus for manufacturing shaped polymeric articles by substantially continuous vacuum forming. The method includes providing a sheet of hot polymeric material which is disposed onto a rotating belt having a mold impression. Vacuum pressure is applied to the polymeric material through the belt so as to draw the hot polymeric material into intimate contact with the mold impression to form a patterned sheet portion and a remaining sheet portion. This method thereafter cools at least the patterned sheet portion below a heat deflection temperature of the polymeric material, forms the remaining sheet portion, and then cools the remaining sheet portion below the heat deflection temperature so that features other than the central pattern, such as nail and butt edges, can be mechanically worked into the polymeric sheet.

Abstract: An apparatus for producing plastic hollow bodies using an extrusion blow molding process has an extrusion unit, which is mounted in a housing, and at least one blow molding station. The extrusion unit has an extruder and an extruder head, connected to the extruder, with at least one extrusion nozzle. The longitudinal extent of the extruder defines a longitudinal direction of the apparatus. The blow molding station has a blow molding table with at least one molding tool, which is provided with an opening disposed on the side of the molding tool toward the extrusion nozzle. The blow molding table is movable on a lateral path, extending essentially perpendicular to the longitudinal direction, from a terminal position laterally of the extruder head into a position beneath the extruder head and back again, in order to make the extrusion nozzle and the opening of the molding tool coincide vertically with one another.

Abstract: Film die (10) for the production of tubular film (3) made of thermoplastic synthetics with at least one feed channel for the synthetic fused material, which ends in a ring-shaped discharge nozzle and is divided into sectors (30) with an interior and/or exterior cooling ring (1) that is adjusted to the diameter of the extruded synthetic tube (3), in which physical parameters of the air blown onto the extruded film tube (3) can be variably changed sector by sector,

Abstract: A plastic resin extrusion line for the production of blown film includes an external thickness control device that provides a controllable amount of air from an inlet side through an annular region to one or two sets of lips. Barriers that can be manually or automatically controlled are provided in the annular region for localized control of air flow and thus for localized thickness control. The pressure drop across the barriers is significant relative to that in the lips.

Abstract: A calibrating basket for a film blowing tube is provided with roller bearings to prevent stripe formation on the film and pinching of the film between the rollers.

Abstract: A mould tool comprises a primary cavity part (201), a core part (202), a secondary cavity assembly (203) and an actuation ring (204). The primary cavity part (201) is attached to the fixed platen of a moulding machine in use and incorporates an injection gate (211). The core part (202) is attached to the moving platen and has a fixed portion (2021) having outside its preform shaping surfaces (20211) four pivot points (224)—of which two are shown—for the secondary cavity petals (2030), of which there are four. Also the core part incorporates a movable portion (2022), comprised of a preform shaping end plate (20221), a carrier (20222) for the end plate, a pair of movement rods (20223) to which the carrier is attached and which are housed in bores (20224) in the core (202) via linear bearings (20225).

Abstract: A method and apparatus for producing an extruded product includes a machine that cooperates with an extruder. The machine is commonly used as a corrugator and the extruded product is often corrugated piping. The machine has a frame supporting a trackway in a continuous path. A plurality of mold block assemblies travel about the continuous path to form a mold tunnel along a portion of the continuous path. The mold block assemblies include a carriage connected by at least one guide and linear bearings to a pair of mold holders. The mold holders are connected to at least one pair of opposing mold blocks. Guides and directors position the mold block pairs relative to one another while the assemblies travel along the continuous path. As the holders, and thus the mold block halves, are linearly displaceable from one another, the halves may meet to form the mold tunnel and separate to allow removal of the extruded product.

Abstract: This invention concerns an apparatus for producing seamless plastic tubes. It has an injection head to which molten plastic material is fed by an extrusion device. The injection head has a plate-shaped distribution device 13a, 13b having an intake opening 20 into which the feed passage 17a, 17b for the molten plastic material opens. In the distribution device, distribution passages 14 extend in a star configuration from the intake opening 20 and extend perpendicularly to the axis of the injection head, wherein each distribution passage 14 has a straight radial passage portion 14r and three branch passages 14z which branch therefrom and which each go into arcuate passage portions 14k which, in the region of the periphery of the distribution device, communicate with the annular gap 25 of the injection head, with the adjacent ends at a respectively identical angular spacing, and they each introduce a respectively identical volume flow into the annular gap 25.

Abstract: An extrusion molding apparatus includes a molding die (3) through which a plasticized and kneaded raw material (1), composed of a synthetic resin material having high heat-resistance and strength, is extruded to form a tubular body (51). The tubular body (51) is passed on a sizing die (4) to cool and harden the tubular body (51) and give it a final inner diameter. The molding die (3) and sizing die (4) are coupled to each other by a connecting pipe (6). The sizing die (4) is made of a carbon material. The connecting pipe (6) supplies a first air (81) to an interior of the sizing die (4). An air lubrication layer is formed between an inner surface (52) of the continuous product (5) and an outer surface (41) of the sizing die (4) by a second air (92) supplied to an interior of the molding die (3).

Abstract: A molding apparatus for molding plastic material with a profiled outer pipe wall has a mold tunnel in which plastic material is shaped to form the pipe. The mold tunnel includes a first plastic cooler against which the plastic material flows for contact cooling of the plastic material. The mold tunnel further includes a second plastic cooler downstream of the first plastic cooler. The second plastic cooler provides an air cooling of the plastic material which surrounds the second plastic cooler in the mold tunnel.

Abstract: A method and apparatus for manufacturing a rubber sheet containing short fibers. The method includes the steps of: mixing short fibers in a flowable rubber matrix; forming the flowable rubber matrix with the fibers therein into a cylindrical shape with a circumferential extent; separating a portion of the circumferential extent from the cylindrical shape, and forming the cylindrical shape with the portion separated into a sheet form.

Abstract: A new plastic tandem extrusion sizer mold. The mold includes an inlet plate, middle plates and an outlet plate which are connected with each other in series by columniform pin, and then side baffles are added to mount on a base with the aid of bolts. A rectangular inlet plate, middle plates and outlet plate, which constitute a cavity of different shape, are placed upright and connected together in sequence and in series. Compared with the conventional sizer mold, the present sizer mold gets over the limitations of cavity parting, machining deep holes, cutting gas slots, trivial design and complex manufacture process, and has a shortened design period and simplified technological process, and can be manufactured rapidly.

Abstract: The invention relates to an air ring for a blown film process, the air ring comprising: at least one air outlet for directing a stream of air outside the film; at least one component movable through a range of positions for controlling the air stream, said component being moveable to a set position within the range of positions for achieving a film of preselected properties; adjustor means for moving the component to any one of the positions; and output generating means for generating a unique output signal for each of said positions in said range to produce a unique signal representative of the set position. The invention also relates to methods of producing blown film. By providing output generating means to produce an output signal which identifies the positions of the components, component settings are reproducible and may be automated.

Abstract: The forming device (3) for an extrusion plant (1) having at least one calibrating device (9) comprising at least one calibration tool (24 to 27) having a plurality of calibration dies (29 to 37), arranged one after the other in an extrusion direction (7), has at least one calibration orifice (38) with several forming surfaces QQ to 42) The calibration dies (29 to 37) have end faces (43, 44) spaced at a distance apart from one another in the extrusion direction (7). At least one cavity (51) is formed between at least two immediately adjacent calibration dies (29 to 37) extending from the forming surface through to a passage applying a vacuum to the cavity, and the cavity (Si) is open across a predominant part of the, periphery of the calibration orifice (38) towards the calibration orifice (38) bounded by the forming surfaces.

Abstract: Provided is a resin guiding device for an inflation molding apparatus, which guides a molten resin extruded and blown into a tubular resin from an inflation molding die, to a pair of take-up rolls, wherein the resin guiding device comprises a pair of guiding members placed between the inflation molding die and the pair of take-up rolls, and the guiding members respectively have curved contact faces which are in contact with the tubular resin where the curved contact faces are mutually outward curved, and each of the curved contact faces has a shape corresponding to a rein shape so as to fold the tubular resin into a flat shape.

Abstract: The present invention is directed to a draw jet for drawing thermoplastic polymer filaments including a drawing slot defined by an entrance member including a converging passageway communicating with a continuing passageway, terminating at an outlet portion, a drawing member including an inlet portion having a drawing gap width of about 2.0 to about 10 mm communicating with the outlet portion of the entrance member, and at least one air nozzle for directing high speed air onto the filaments in a downstream direction positioned between the outlet portion of the entrance member and the inlet portion of the drawing member, and with a nozzle gap width wherein the gap ratio of the drawing gap width to the combined width of all of the nozzle gaps is from about 1.0 to about 10.

Abstract: Mold blocks and methods for thermoforming corrugated plastic pipe that provide a uniform vacuum on the internal lateral surface and optimize forced convective cooling on exterior surface is disclosed. Mating mold blocks have an interior surface with transverse corrugations and an exterior lateral surface having transverse channels containing radial slots that intersect circular slits formed in the interior mold surface. The channels are fitted with a dual cover arrangement that serves to provide (1) a low-resistance vacuum path to the slits located on the interior surface and (2) a forced convective heat transfer path to cool the mold blocks. The cover arrangement is removable, providing a convenient means of inspecting, maintaining and modifying the mold blocks.

Abstract: A molding apparatus which is used in a continuous molding operation includes an endless looped track, track carriers which are moved around the track to and from a product shaping mold region and a transfer system for replacement of mold block members used in the apparatus. The transfer system, which operates without interrupting the molding operation includes transfer carriers controlled to move synchronized with the track carriers at a transfer location remote from the mold region and actuators which slide the mold block members between the track carriers and the transfer carriers at the transfer location when the transfer carriers are synchronized with the track carriers.

Abstract: A manufacturing apparatus and method for multiple containment tubing produces continuous, nested tubing, or one tube within another tube, without having to fix the space between the tubes or position them concentrically. Consequently the tubing is very flexible and with uniform wall thickness. Moreover, because the inner surface of the outer tube and the outer surface of the inner tube are ribless, these kinds of features cannot interfere with the bending and twisting and the operation of the tubes comprising the tubing. The space between the tubes, or free space, has sufficient volume to contain a range of contents of the inner tube, as a safety containment device, if the inner tube ruptures, cracks, or otherwise breaks.

Abstract: An internal bubble cooling air control system in a blown film apparatus has sensors arranged to increase response time and reduce interference, and includes a high speed valve for fast actuation of air flow from a controller in response to signals received from the sensors.

Abstract: A calibration device for flat extruded sections comprises at least two flat calibration plates (10) parallel to one another at a distance apart such as to form a gap (1) through which an extruded section (11) can pass, each calibration plate comprising cooling means for cooling the plate and vacuum-forming means for creating a vacuum in the gap (1), the calibration device comprising air-intake means for introducing air into the gap (1), the air-intake means being designed to form air cushions or pads between the flat surfaces of the extruded section (11) and the flat surfaces of the calibration plates (10).

Abstract: A tubular film blowing head is provided with one outer and one inner nozzle ring between which a ring chamber is formed extending in a conical or parabolic manner towards the circular nozzle gap and of which the inner nozzle ring, which is provided with a central bore for exchanging the pressurized air, is connected by means of a screw connection to a central cone piece of the blowing head. This central cone piece has a bore that is aligned to the central bore. In order to create a screw connection between the inner nozzle ring and the center cone piece that is firm and simple to produce, the inner nozzle ring is connected to the central cone piece by means of a threaded bolt penetrating the central bore of the nozzle ring and provided with an axial bore in that the threaded bolt is screwed into the bore of the cone piece, which is embodied as a threaded bore.

Abstract: Proposed is a device for continuously producing seamless plastic tubes, wherein provided as a distributor element for the molten material to be fed to an annular gap is a distributor plate which is arranged within the cross-section of the mold cavity and in which the molten plastic material is passed to the peripheral surface of the distributor plate substantially radially with respect to the direction of production by way of distribution passages which branch tree-like, wherein the flow path of the molten plastic material is the same in each of the individual distribution passages between the entry opening and the peripheral surface

Abstract: A method for continuously forming discrete hollow parts includes extruding at least one continuous stream of molten plastic. A plurality of mold segments are arranged such that one or more segments periodically close on the one or more streams of molten plastic and define discrete part forming cavities when closed. A pressure differential is created within the discrete part forming cavities to shape the molten plastic accordingly. Air or another gas is replenished within the discrete hollow parts either in the discrete part forming cavities, or nearly immediately upon discharge from the cavities. The discrete hollow parts are then cooled. The apparatus for forming discrete hollow parts in this manner has an extruder and a plurality of the mold segments including one or more segments that can be closed on the plastic stream or streams. The pressure differential is applied by the apparatus to the closed mold segments. The hollow part interior is replenished either by the apparatus or manually by an operator.

Abstract: The invention concerns a continuous manufacturing method which consists in producing a blank (E) by extrusion, bringing said blank to a temperature for molecular orientation, passing said blank around a radial expansion mandrel (12); gauging and cooling while subjecting the blank to axial traction. The radial expansion produced on the mandrel (12) is partial so that the internal diameter (B) of the blank (E), when it leaves the mandrel, is less than the nominal internal diameter (D) of the finished tube, performing an additional radial expansion of the blank, up to its nominal diameter, by internal fluid pressure. In permanent operating conditions, the inner surface of the blank (E) is no longer in contact with the mandrel (12).

Abstract: Pipe molding apparatus having a molding mold tunnel includes an upstream (3) and at least one downstream mold block (7). Each mold block (3, 5, 7) comprises mold block sections which close with one another to form the pipe and which open relative to one another to release the pipe. The mold blocks (3, 5, 7) move downstream of the apparatus together with one another when forming the pipe and move upstream separately from one another when releasing the pipe which cools and shrinks in both diameter and length in the mold tunnel. Each mold block (3, 5, 7) has a hollow pipe forming region with the pipe forming region of the downstream mold block being decreased in both diameter and length relative to the pipe forming region of the upstream mold block (3) to compensate for the plastic shrinkage.

Abstract: An apparatus for producing an extruded film tube and supplying said tube to a collapsing and roller assembly includes a die for extruding a molten material in the form of a tube which is in a molten state below a frost line and in a solid state above the frost line. A blower system supplies and exhausts cooling air to and from an interior portion of the tube, and is regulated by a valve. At least two sensors are provided, one below the frost line for sensing the position of said tube, and one located proximate the tube in a position above said frost line. The upper sensor is used for sensing the position of the tube prior to collapsing and flattening it. A controller receives feedback signals from both sensors and controls operation of the valve.

Abstract: The present invention includes an extrusion line system capable of simultaneous running and retooling. The invention utilizes a turret device having an upper surface adapted to rotate about a central point. The turret device has on its upper surface a first and second production line portion. The production line portions are positioned on the upper surface such that when the turret device is in one position the first production portion may be used with an extrusion device. When the turret device is in a second position, the second production portion may be used. This approach allows retooling of one of the production portions while the other production portion is running on the line.

Abstract: In the production of a spunbond web by aerodynamically stretching thermoplastic filaments from a spinneret, the stretching nozzle is formed by two nozzle-forming units each of which has a temperature control device, especially a heater, to minimize deformation at the stretching nozzle defining wall. The result is a reduction in the tolerance of the basis weight of the spunbond web.

Abstract: A method and an apparatus for manufacturing a ceramic honeycomb molding having many cells formed by arranging cell walls in a honeycomb pattern. Deformation, wrinkles, cracks, etc., of the cell walls and the like are prevented from occurring. The method for manufacturing the ceramic honeycomb molding having many cells formed by arranging cells walls in a honeycomb pattern comprises an extruding process in which clayey honeycomb moldings 1 are extruded, a drying process in which the honeycomb moldings 1 are dried, and a storage process, between the extruding process and the drying process, in which the honeycomb moldings 1 are maintained in a high humidity atmosphere.

Abstract: Apparatus for producing plastic film, of the type in which molten plastic is extruded through an annular die to form a tubular bubble which is expanded by air blown into the bubble, and a collapsing frame for forming the bubble into a flat tube prior to passing the tube through a nip formed between rollers, in which opposed, converging reaches of endless belts are used for the collapsing. The belts have their upstream ends held by a pair of first rollers spaced apart on opposite sides of the bubble, and have their downstream ends held by a pair of nip rollers which hold the belts together to form a nip for the collapsed tube. Pulleys and a belt, or gears, are provided which rotatably interconnect the pinch rollers and ensure that the belts entering the nip travel at the same surface speed.

Abstract: An internal bubble cooling air control system in a blown film apparatus has sensors arranged to increase response time and reduce interference, and includes a high speed valve for fast actuation of air flow from a controller in response to signals received from the sensors.

Abstract: This invention describes a process for orienting and drawing multiple-layer thermoplastic materials, in particular of a tubular type, wherein