Abstract: 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.

Abstract: The invention describes a method for monitoring a film bubble (6) in an outlet region after it emerges from an outlet die and before it leaves a calibration apparatus of a blow film line, the method comprising the following steps: detecting the wavelength of the radiation emitted from at least two different locations of the outer surface of the blown film at different points in time following one another by means of at least one optical sensor determining locations of the same wavelength determining the variation over time of the locations of the same wavelength.

Abstract: The invention relates to a monitoring method for monitoring a film bubble (FB) in a discharge region (112) downstream of a discharge nozzle (110) of a blown film device (100), comprising the following steps: optically detecting at least one contour parameter (KP) of a film contour (FK) of the film bubble (FB) in the discharge region (112), comparing the at least one detected contour parameter (KP) with a specific preset value (VW), determining a contour deviation (KA) between the at least one detected contour parameter (KP) and the specific preset value (VW), outputting the contour deviation (KA) as monitoring result (UE).

Abstract: 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.

Abstract: The invention relates to a monitoring method for monitoring a film bubble (FB) in a discharge region (112) downstream of a discharge nozzle (110) of a blown film device (100), comprising the following steps: optically detecting at least one contour parameter (KP) of a film contour (FK) of the film bubble (FB) in the discharge region (112), comparing the at least one detected contour parameter (KP) with a specific preset value (VW), determining a contour deviation (KA) between the at least one detected contour parameter (KP) and the specific preset value (VW), outputting the contour deviation (KA) as monitoring result (UE).

Abstract: The invention describes a method for the production and further processing of a film tube (6), in which method a plastic melt is transferred into a cylindrical melt by means of an extrusion die (4), the melt flow is drawn out through an annular gap (5) associated with the extrusion die (4) in order to form the film tube (6), and at least one temperature-controlled volume flow comprising at least one fluid is conducted by means of a temperature control device (8) onto the outer periphery of the film tube (6), wherein the temperature control device (8) is divided into peripheral segments, wherein a volume flow of different magnitude and/or different temperature is produced by means of each peripheral segment such that the temperature control of the film tube (6) differs over the periphery of the film tube, and wherein the film tube (6) is flattened by means of a flattening device (9), the flattening device (9) being rotated in relation to the extrusion die (4).