Method for adjusting the profile of a film in blown extrusion lines, adjusted film and reel

A method for active adjustment of a monolayer or multilayer film profile, in an extrusion line with blown technology, said method comprising:

• a step of actively adjusting the film profile, wherein said film profile is generated with a sinusoidal wave, transversely movable, with an amplitude substantially equal to a profile tolerance reached with a basic adjustment of the film profile and having a variable sliding frequency,
• wherein the step of actively adjusting the film profile is performed with a disk with “n” segments, physically divided from each other, which regulate quantity, temperature, or both the quantity and the temperature of a flow of cooling air,
• wherein the sinusoidal wave has the amplitude and a frequency proportional to an extent of a defect not corrected by a basic adjustment system of the film profile,
• wherein the amplitude of the sinusoidal wave is defined in an initial development step of film production, and
• wherein a thickness is detected, and consequently profile defects, in each point of a film produced with the basic adjustment.