The disclosure relates to forming shaped thermoplastic articles having smooth peripheries. Many thermoplastic articles have sharp edges formed upon molding or cutting the article from a feedstock sheet. Such sharp edges can damage thin plastic films or flesh which they contact, and smoothing the edges is desirable. Described herein are methods of forming a smooth periphery for such sharp-edged articles by rolling over the sharp edge. The smoothing operation is performed by forming a deflectable flange including a bend region separated from the potentially sharp peripheral edge by a spacer, deflecting a portion of the deflectable flange, and softening at least one bent portion of the deflectable flange to yield a smooth periphery upon cooling.

An air ring has a main body including a plenum through which pressurized air enters the air ring, the main body including a generally circular interior that is unobstructed vertically above the main body. A generally circular forming-cone assembly is received in the generally circular interior of the main body, and includes at least one annular lip defining a passage through which pressurized air from the plenum exits the air ring for impingement upon the polymer tube. A plurality of fasteners secure the forming-cone assembly in the interior of the main body, the fasteners and forming-cone assembly being unobstructed vertically above the air ring, wherein the fasteners are accessible from vertically above the air ring and the forming-cone assembly is removable from the main body by vertical lifting without removal of other components from the air ring.

The present invention relates to an external cooling system for a molten film tube produced by a blown film tubular extrusion process. Embodiments of the present disclosure provide a unidirectional cooling element having a unidirectional cooling interface containing a cooling gas deflector spaced adjacent to the molten film tube. The unidirectional cooling element operably expels cooling gas in a path with the flow of the molten film tube toward an exit gap formed between the unidirectional cooling interface and the molten film tube. The minimum gap between the unidirectional cooling interface and the molten film tube occurs at the exit gap, and advantageously, the unidirectional cooling interface is provided with one or more compound angles to maximize stability and cooling efficiency.

A method for post-tempering a film tube extruded by a blown film line includes: ejecting the film tube in a haul-off direction along a longitudinal axis of the blown film line by a blow head; blowing cooling gas onto the film tube relative to the haul-off direction downstream of the blow head to solidify the film tube at a frost line; post-tempering the film tube by a post-tempering unit having a plurality of adjustable blowing elements downstream of the frost line for blowing tempering gas onto the film tube; adapting a diameter of a feed-through opening formed by the blowing elements to a diameter of the film tube by adjusting the blowing elements; measuring the actual temperature of the film tube downstream of at least one of the blowing elements; and regulating the temperature of the film tube to a target temperature by blowing tempering gas onto the film tube.

The present invention relates to an external cooling system for a molten film tube produced by a blown film tubular extrusion process, comprised of one or more enclosures with one or more respective cavities that directly receive a portion of cooling gas emanating from one or more associated cooling elements. Each enclosure includes a port containing a variable exhaust device and optional flow buffer, acting to maintain a pressure differential between the cavity and an adjacent inside volume of the molten film tube, adjustable to optimize molten film tube stability cooling element efficiency and spaced apart dimension between cooling elements. Significant increases in production speeds are achieved with improved film quality over an increased range of tubular film sizes, down to a minimum size which occurs when operating at zero internal to molten film tube pressure.

The invention describes a method for producing a plastics film by a film-extruding machine, wherein at least two plastics materials from at least two reservoirs are fed together to one extruder or are each fed to a respective extruder, the plastics materials are melted in the extruder or in the extruders and are conveyed as a melt strand or as melt strands into a die head, the melt Strand or the melt strands are spread out flat in the die head and is/are extruded from a die of the die head as a melt film, and the melt film and/or the film sheet formed by cooling is/are drawn off by at least one take-off roll. It should particularly be noted that measured values are recorded by means of a measuring device for at least one property of at least one plastics material and/or at least one melt strand /d/ or the melt film and/or the film sheet and/or for a machine parameter of the film-extruding machine and that a first plastics material is a plastics material with varying material properties and a second plastics material is a plastics material with substantially constant material properties, wherein the first and the second plastics materials are fed to the extruder or the extruders in relative proportions, the relative proportions being varied according to the measured values for the property.

The present invention relates to an apparatus for producing inline stretched tubular foils by the blowing process, having a blown foil system comprising an extruder, a blowing head, a cooling ring, a calibrating basket, a flat laying unit and a reversing turret haul-off, having a stretching system for monoaxially stretching the laid flat foil in the machine direction and with a first thinness control system which operates segmented control zones in the cooling ring to form thinness sections so that, during stretching, a foil is produced with a thickness profile having the smallest possible deviations from the medium foil thickness over the complete foil width. To increase the accuracy and speed of the first thinness section control system, a second thinness section control system is provided which controls two opposing heat sources between the calibrating basket and the flat laying unit and which can be connected to the first thinness section control system.

The invention relates to a blown film system for producing a film tube made of plastics material, comprising: an annular nozzle, out of which a plastic melt having a closed cross-section can be brought; a take-up device, by means of which the plastic melt can be drawn up from the direction of the annular nozzle so as to form the film tube; an air-provision device, which is downstream of the annular nozzle when viewed in the transport direction of the film tube and by means of which an amount of air can be provided; and a calibration device, which is downstream of the annular nozzle when viewed in the transport direction of the film tube and surrounds the film tube and by means of which the outer circumference of the film tube can be delimited. At least one detector is contained that has a plurality of detection elements, by means of which electromagnetic radiation emitted or reflected at various points of the film tube can be detected, such that at least one planar region and/or contoured region of the film tube can be detected with regard to characteristic properties, wherein the detector comprises at least 32 detection elements.

A cooling ring for cooling a film tube (14) in a film blowing installation, includes a cooling gas inlet (18), a distribution system (20) for distributing the cooling gas over the circumference of the film tube (14), a supply gap (28) for guiding the cooling gas in a radial direction towards the film tube, a cooling gas outlet forming an annular gap (34) that surrounds the film tube and is tilted at a tilt angle relative to the radial direction, a flexible adjusting ring (36; 36) arranged circumferentially in the annular gap, and a collar of individually controllable adjusting elements (44; 44) for local radial deformation of the adjusting ring, the adjusting ring arranged in engagement with a wall (32; 38) of the annular gap and forming a limiting wall (42) for the cooling gas flow exiting from the annular gap, the wall extending continuously in circumferential direction.

The disclosure relates to forming shaped thermoplastic articles having smooth peripheries. Many thermoplastic articles have sharp edges formed upon molding or cutting the article from a feedstock sheet. Such sharp edges can damage thin plastic films or flesh which they contact, and smoothing the edges is desirable. Described herein are methods of forming a smooth periphery for such sharp-edged articles by rolling over the sharp edge. The smoothing operation is performed by forming a deflectable flange including a bend region separated from the potentially sharp peripheral edge by a spacer, deflecting a portion of the deflectable flange, and irreversibly bending, without heating, at least one bent portion of the deflectable flange to yield a smooth periphery upon cooling.