Patent ID: 8956136
Filing Date: 2015-02-17
Classification: B29C,B29L

Abstract:
1. A device for cooling blown film comprising thermoplastic plastics during the production of blown film for being arranged at a blown film extruder with a film blowing head, the film blowing head comprising: an annular nozzle from which the blown film is guided away in an extraction direction, and further comprising at least three annular cooling gas nozzles arranged at a distance from the annular nozzle thereby forming at least three blowing-out planes, wherein at least one of the at least three annular cooling gas nozzles is directed against the extraction direction of the blown film, at least one of the at least three annular cooling gas nozzles is directed in a radial direction toward the blown film, and at least one of the at least three annular cooling gas nozzles is directed in the extraction direction of the blown film, and wherein the at least one annular cooling gas nozzle directed in a radial direction toward the blown film is arranged between the at least one annular cooling gas nozzle directed against the extraction direction of the blown film and the at least one annular cooling gas nozzle directed in the extraction direction of the blown film, wherein the at least one annular cooling gas nozzle directed against the extraction direction of the blown film and the at least one annular cooling gas nozzle directed in the extraction direction of the blown film provide a common cooling ring and are fed from a common annular chamber, wherein on the inside of the annular chamber an annular exit gap is provided, said annular exit gap being divided into channels for supplying all of the at least three annular cooling gas nozzles, further comprising at least one variable controlling means, said at least one variable controlling means selected from the group consisting of means for circumferentially variably controlling in sectors the volume flow of said annular cooling gas nozzles and means for circumferentially variably controlling in sectors the temperature of the cooling gas flow of said annular cooling gas nozzles, wherein said annular exit gap being provided with radial channels, and wherein the variable controlling means has independently controlled setting elements provided in the annular chamber or in the annular exit gap so as to vary the free passage cross-sections of the radial channels or the temperature in sectors.