Abstract: A nozzle ring of an extruder for blowing tubular plastics film is divided into cooling sectors provided with adjusting elements. The thicknesses of the blown film are measured over the circumference thereof and a number of film sectors of equal circumferential length corresponding to the number of cooling sectors is established from the measured thicknesses. Assuming that the film sector of maximum or minimum thickness has been extruded in the correct position for the purpose of determining the cooling sector associated with the film sector, the subsequent film sectors are in turn allocated to successive cooling sectors. From the measurements, the mean thickness distributions are determined over the individual film sectors. These values of mean thickness distribution define a measure for the correcting command for the adjusting elements of the cooling sectors that are associated with the respective film sectors.

Abstract: A nozzle ring of an extruder for blowing tubular plastics film is divided into cooling sectors provided with adjusting elements. The thicknesses of the blown film are measured over the circumference thereof and a number of film sectors of equal circumferential length corresponding to the number of cooling sectors is established. Assuming that the film sector of maximum or minimum thickness has been extruded in the correct position for the purpose of determining the cooling sector associated with the film sector, the subsequent film sectors are in turn allocated to successive cooling sectors. The mean thickness distributions are determined from the measurements over the individual film sectors.

Abstract: A nozzle ring of an extruder for blowing tubular plastics film is divided into correcting sectors provided with adjusting elements. The thicknesses of the blown film are measured over the circumference thereof and a number of film sectors of equal cross-sectional area corresponding to the number of correcting sectors is established from the measured thicknesses. Assuming that the film sector of maximum or minimum thickness has been extruded in the correct position for the purpose of determining the correcting sector associated with the film sector, the subsequent film sectors of equal cross-sectional area are in turn allocated to successive correcting sectors. The throughput and cross-sectional area or temperature of the respective correcting sector is adjusted until the circumferential lengths of the film sectors are equal.

Abstract: A nozzle ring of an extruder for blowing tubular plastics film is divided into cooling sectors provided with adjusting elements. The thicknesses of the blown film are measured over the circumference thereof and a number of film sectors of equal circumferential length corresponding to the number of cooling sectors is established from the measured thicknesses. Assuming that the film sector of maximum or minimum thickness has been extruded in the correct position for the purpose of determining the cooling sector associated with the film sector, the subsequent film sectors are in turn allocated to successive cooling sectors. From the measurements, the mean thickness distributions are determined over the individual film sectors. These values of mean thickness distribution define a measure for the correcting command for the adjusting elements of the cooling sectors that are associated with the respective film sectors.