Abstract: A method for controlling the thickness of an extruded, biaxially elongated film product, in which thickness deviations are controlled automatically and without supervision.In the method, correlation between positions along the widthwise direction of a film sheet and positions of die manipulation bolts of an extrusion die is obtained, and initially, a profile of the film sheet prior to lateral elongation is converged into a tolerable range; thereafter, the thickness of the film sheet after lateral elongation is measured, and if there are thickness deviations outside the tolerable range, a thickness regulation is effected by transmitting a signal corresponding to the thickness deviations to the appropriate die manipulation bolts.

Abstract: A method and apparatus for winding or rewinding a film wherein a pressurized jet of air is directed onto a surface of an unsupported portion of the film being wound or rewound. The air jet is elongated transversely of the length of said film. Simultaneously with the application of the air jet to the film the air impinging on the surface of the film is collected by suction.