Disclosed is an apparatus for the production of a blown tubular film (FT). The apparatus includes an independent device for the localized thickness adjustment at the strips adjacent to the folding edges resulting from the flattening of the tubular film (FT) by means of adjustment elements formed in angular sectors of limited extension symmetrically arranged 180° apart. The independent device for the localized thickness adjustment being a volumetric type device having a rotating ring that performs a rotating adjustment of the flow rate of a cooling air stream which takes into account the angular offset resulting from the operational parameters of the apparatus.

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 a method and apparatus for cooling. An apparatus includes an annular cooling ring operable for receiving a flow of a molten film bubble and expelling a flow of cooling gas, the annular cooling ring comprising a middle lip and an adjacent radially spaced apart outer lip, the middle lip having an extended length longer than the outer lip, a radially inner surface of the outer lip and a radially outer surface of the middle lip define a channel operable to allow the flow of cooling gas along the radially outer surface of the middle lip, wherein the middle lip is located radially intermediate the channel and the molten film bubble, and wherein the middle lip isolates the molten film bubble from the flow of cooling gas until the flow of cooling gas passes beyond the extended length of the middle lip

A process for manufacturing a tubular film such as an edible casing film or a packaging film. The process includes the steps of providing a preblended powder composition containing a polymer matrix, a plasticizer, and water; feeding the preblended powder composition to an extruder; heating the preblended powder composition to a temperature above 100 degrees Celsius for a sufficient time to fully hydrate the polymer matrix and to convert the powder composition to a flowable mass; and extruding the flowable mass through a tubular die of the extruder to form the tubular film. The tubular film comprises: about 40-75 wt % polymer matrix; about 10-35 wt % plasticizer; and about 10-35 wt % water. The polymer matrix component is fully hydrated under the temperature, pressure and shear conditions inside the extruder, and may have a component which is only fully hydrated at temperatures above about 100 degrees Celsius.

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. Additionally, at least one cooling element is provided, comprised of a divergent cooling element with a divergent cooling interface containing a cooling gas deflector spaced adjacent to the molten film tube and providing an expelled cooling gas.

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. Additionally, at least one cooling element is provided, comprised of a divergent cooling element with a divergent cooling interface containing a cooling gas deflector spaced adjacent to the molten film tube and providing an expelled cooling gas.

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. Additionally, at least one cooling element is provided, comprised of a divergent cooling element with a divergent cooling interface containing a cooling gas deflector spaced adjacent to the molten film tube and providing an expelled cooling gas.

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 cooling device for external cooling of a film tube subjected to internal pressure in the production of blown films of thermoplastic material includes a cooling gas ring with a ring housing and a ring nozzle arranged concentrically to a central axis and being open towards the film tube. At least one inner ring channel extending in the circumferential direction about the central axis and being open radially inwards towards the ring nozzle is included. At least one feed channel for supplying cooling gas is attached to the ring housing and connected to the ring channel. The cooling device also includes at least one flow guiding device arranged in the at least one feed channel. When a cooling gas flows through the flow guiding device, at least a partial flow of the cooling gas is set in rotation about a flow axis prior to flowing into the ring channel.

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. The deflection can include curling the spacer at or near the peripheral edge. The methods can be performed incrementally and/or in a reciprocating fashion.