Method and apparatus for controlling film thickness in a film blowing apparatus

摘要

Film thickness is recorded around the circumference of the tubular film(6) and compared with a set value to produce a controlling variable for adjustment of the thickness profile. The controlling variable is realized through measurement of either a single or several individual layer thicknesses. An Independent claim is made for a film blowing plant for production of multi-layer tubular film. A non-contact sensor(18) working on the principal of white light interferometry measures thickness in single or multiple layers of the tube. An analyzing unit is also employed for comparison of a measured thickness profile with a set profile to produce a controlling variable.