Abstract: 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.

Abstract: A cooling device for the 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 and at least one feed channel for supplying cooling gas is attached to the ring housing. The at least one feed channel is connected to the ring channel. The cooling device also includes at least one flow guiding device which is arranged in the at least one feed channel and is configured such that 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.

Abstract: A calibration device for calibrating an extruded film tube, above the frost line, forms an annular gap between the calibration device and the film tube. The calibration device includes a plurality of calibration segments and at least one blowing nozzle. The plurality of calibration segments are distributed around a longitudinal axis and form a central feed through opening for feeding through the film tube along the longitudinal axis. The calibration segments are adjustable for adjusting the diameter of the feed through opening. The at least one blowing nozzle for each calibration segment, feeds a calibration gas to the feed through opening. The at least one blowing nozzle is formed such, that the calibration gas is guided to the annular gap substantially parallel to a surface of the film tube and that the calibration gas flows through the annular gap in a single flow direction.

Abstract: A calibration device for calibrating an extruded film tube, above the frost line, forms an annular gap between the calibration device and the film tube. The calibration device includes a plurality of calibration segments and at least one blowing nozzle. The plurality of calibration segments are distributed around a longitudinal axis and form a central feed through opening for feeding through the film tube along the longitudinal axis. The calibration segments are adjustable for adjusting the diameter of the feed through opening. The at least one blowing nozzle for each calibration segment, feeds a calibration gas to the feed through opening. The at least one blowing nozzle is formed such, that the calibration gas is guided to the annular gap substantially parallel to a surface of the film tube and that the calibration gas flows through the annular gap in a single flow direction.

Abstract: An apparatus for the manufacture of a thermoplastic blown film is provided having a blower head for extruding a film tube of a thermoplastic material. An annular ring is provided for blowing a cooling gas on an outside surface of the film tube to solidify the film tube. This cooling gas is directed in a flow direction parallel to a wall of the film tube. The cooling gas is drawn off the tube by means of a suction ring positioned around the tube prior to flattening the tube to form a film tube.

Abstract: A process of controlling the thickness profile of a blown tubular film, consisting of thermoplastic plastics, around the circumference of same when producing blown film by means of blown film extruders, having a film extrusion die, wherein a measuring device measures the film thickness of the tubular film around the circumference and wherein a control device variably controls the cooling gas flow as a function of the measured film thicknesses around the circumference in sectors, wherein cooling gas flows are supplied from the outside in the direction of production in two separate planes, and wherein the cooling gas flows are controlled variably and in circumferential sectors around the circumference in the two planes in respect of their physical parameters.

Abstract: A process for the manufacture of a thermoplastic blown film is disclosed. The process includes the step of extruding a blown film tube of a thermoplastic material. The outside surface of the film tube is treated with a cooling gas to solidify the film tube. This cooling gas is directed to the tube from an annular ring around the tube and the cooling gas is directed at the tube in a flow direction parallel to a wall of the film tube. The cooling gas is drawn off the tube by means of a suction ring positioned around the tube prior to flattening the tube to form a film.