Abstract: A method for producing reels of plastic film by cast extrusion process is described. The steps include causing the film to flow from an extrusion head slit, adjusting its thickness, drawing the exiting film with an internally cooled roll, winding the film downstream of the roll to form reels of film, measuring the thickness of the film and adjusting the thickness of the film based on the thickness measurements provided by the thickness measuring device. The method further includes measuring a reference quantity of the film reels produced, comparing the reference quantity measured value with a design value of the reference quantity corresponding to the design value of the thickness of the film and if the measured value is different from the design value of the reference quantity, acting on adjustment means and/or on the thickness measuring device to obtain a desired film thickness.

Abstract: A device for retaining and removing filaments of plastic material, or angel's hairs, from a flow of plastic material in form of granules, powders or flakes is disclosed. The device includes a main body defining a through channel through which the plastic material flows, a plurality of retractable elements carried by the main body and are movable between a retracted position, in which they leave the through channel unobstructed, and an extracted position, in which they protrude into the through channel for trapping the angel's hairs flowing together with the flow of plastic material along the through channel, and an actuating system for moving each retractable element between the retracted and extracted positions.

Abstract: A device for retaining and removing filaments of plastic material, or angel's hairs, from a flow of plastic material in form of granules, powders or flakes is disclosed. The device includes a main body defining a through channel through which the plastic material flows, a plurality of retractable elements carried by the main body and are movable between a retracted position, in which they leave the through channel unobstructed, and an extracted position, in which they protrude into the through channel for trapping the angel's hairs flowing together with the flow of plastic material along the through channel, and an actuating system for moving each retractable element between the retracted and extracted positions.

Abstract: A method is described for measuring, in a multi-layer film obtained by blow extrusion process and formed by one or more layers of a first material and a second material, the total thickness of the first material and/or the second material. The method includes the steps of: a) acquiring by means of an X-ray sensor a first measurement signal representative of the total thickness of the film; b) acquiring by means of a capacitive sensor a second measurement signal which is the sum of the signals given by the first and second materials of the film. The signal given by each material of the film is a function of the thickness of the material; and c) calculating, from the first and second signals, the total thickness (L1 of the first material and/or the total thickness (L2) of the second material.

Abstract: A method is described for measuring, in a multi-layer film having one or more layers of a first and a second material, the total thickness of the first material and/or the second material. The method includes: a) acquiring, by means of an optical or an ionizing radiation sensor, a first measurement signal (Sott) representative of the total thickness of the film; b) acquiring, by means of a capacitive sensor, a second measurement signal which is the sum of the signals given by the first and second material of the film. The signal given by each material of the film is a function of the thickness of the material; and c) calculating, from the first and second signal, the total thickness of the first material and/or the second material.

Abstract: A method for producing reels of plastic film by cast extrusion process is described. The steps include causing the film to flow from an extrusion head slit, adjusting its thickness, drawing the exiting film with an internally cooled roll, winding the film downstream of the roll to form reels of film, measuring the thickness of the film and adjusting the thickness of the film based on the thickness measurements provided by the thickness measuring device. The method further includes measuring a reference quantity of the film reels produced, comparing the reference quantity measured value with a design value of the reference quantity corresponding to the design value of the thickness of the film and if the measured value is different from the design value of the reference quantity, acting on adjustment means and/or on the thickness measuring device to obtain a desired film thickness.

Abstract: A system for the treatment of plastic films is described. The system includes a stretching station which stretches the film by subjecting it to permanent longitudinal expansion and a reinforcing station upstream of the stretching station. The reinforcing station reinforces edge areas on opposite sides of the film while the film is advanced along a feed direction, so as to increase the transversal tensile strength of the edge areas of the film. The reinforcing station also increases the thickness of the edge areas of the film and, for this purpose, includes a pair of applicator devices, each of which are associated with a film edge zone and are arranged to apply additional material on the edge areas.

Abstract: Disclosed is an apparatus for the production of a blown tubular film (FT). The apparatus includes an independent device for the localized thickness adjustment at the strips adjacent to the folding edges resulting from the flattening of the tubular film (FT) by means of adjustment elements formed in angular sectors of limited extension symmetrically arranged 180° apart. The independent device for the localized thickness adjustment being a volumetric type device having a rotating ring that performs a rotating adjustment of the flow rate of a cooling air stream which takes into account the angular offset resulting from the operational parameters of the apparatus.

Abstract: Disclosed is an apparatus for the production of a blown tubular film (FT). The apparatus includes an independent device for the localized thickness adjustment at the strips adjacent to the folding edges resulting from the flattening of the tubular film (FT) by means of adjustment elements formed in angular sectors of limited extension symmetrically arranged 180° apart. The independent device for the localized thickness adjustment being a volumetric type device having a rotating ring that performs a rotating adjustment of the flow rate of a cooling air stream which takes into account the angular offset resulting from the operational parameters of the apparatus.

Abstract: Disclosed is an apparatus for the production of a blown tubular film (FT). The apparatus includes an independent device for the localized thickness adjustment at the strips adjacent to the folding edges resulting from the flattening of the tubular film (FT) by means of adjustment elements formed in angular sectors of limited extension symmetrically arranged 180° apart. The independent device for the localized thickness adjustment being a volumetric type device having a rotating ring that performs a rotating adjustment of the flow rate of a cooling air stream which takes into account the angular offset resulting from the operational parameters of the apparatus.

Abstract: A device arranged in the cooling ring of an apparatus for the production of blown films in order to adjust the thickness profile thereof is disclosed. The device includes a plurality of equally spaced motor-driven actuators that adjust the flow rate of the flow of a cooling fluid directed towards a forming cone, as well as a plurality of equally spaced resistances provided with finned dissipators arranged in the path of the cooling flow. In this way, the device combines the characteristics of low power consumption and high adjustment velocity of a volumetric device with the higher angular resolution achievable through the heating elements of a thermal device, and all of this with an operating method that prevents the risks of bubble instability or adhesion, achieves a high energy efficiency and guarantees a wide thickness adjustment range.