Abstract: A method for perforating a film of plastic material in which the film is perforated whilst it is slid through a perforating device by a plurality of pressurised hot gas jets having a temperature above the melting temperature of the main film, in which the hot gas jets are correlated with the sliding speed of the main film, and in which reinforcing bands obtained from an auxiliary film of plastic material are connected to the perforated main film, making the reinforcing bands adhere between parallel rows of base holes. During perforating, the main film of plastic material is pressed against a perforating template, making the main film of plastic material instantaneously penetrate openings of the perforating template by said hot gas jets. A hot gas perforating device and a suitable apparatus for perforating and stretching a film of plastic material are also provided.

Abstract: A machine for manufacturing pre-stretched extendable film rolls provides for a pre-stretch unit (10) of the film (F) and a wrapping unit (100) of the film in roll provided with a series of rolls around which the advancing film is partially wrapped; the pre-stretch unit (10) provides for, in sequence, at least a first pre-stretching roll (12), a pre-stretching auxiliary roll (13) acting against the first roll (12) with the interposition of the film, and a second pre-stretching roll (14) having a speed greater than the speed of the first roll (12) to carry out the pre-stretching of the film; the wrapping unit provides for a wrapping roll (104) for wrapping the pre-stretched film; the pre-stretch unit (10) further provides for a detensioning roll (17) arranged downstream said second pre-stretching roll (14) and having a speed less than said second pre-stretching roll (14) and greater than said wrapping roll (104), so as to obtain a first detensioning of the film after the pre-stretching operation and a second de

Abstract: A machine for producing coils of prestretched extendible film has a prestretching unit (10) for prestretching the film (F) and a winding unit (100) for winding the film in a coil provided with a series of rollers around which the advancing film winds partially; the winding unit comprises a winding roller (104) in pressing contact against the coil (R) of the prestretched film in winding progress; to obtain coils of constant diameter and high winding quality the final contact position is varied of the winding roller (104) against the coil (R) according to the length of the wound film and according to the required diameter of coil.

Abstract: A method for perforating a film of plastic material in which the film is perforated whilst it is slid through a perforating device by a plurality of pressurised hot gas jets having a temperature above the melting temperature of the main film, in which the hot gas jets are correlated with the sliding speed of the main film, and in which reinforcing bands obtained from an auxiliary film of plastic material are connected to the perforated main film, making the reinforcing bands adhere between parallel rows of base holes. During perforating, the main film of plastic material is pressed against a perforating template, making the main film of plastic material instantaneously penetrate openings of the perforating template by said hot gas jets. A hot gas perforating device and a suitable apparatus for perforating and stretching a film of plastic material are also provided.

Abstract: A spindle (10) suitable for winding up coreless rolls (11) of a stretchable plastic film; the spindle (10) comprises a tubular body having a peripheral wall (12) defining at least one internal chamber (14) connectable to a pressurized air source. A plurality of perforations (17) extends from the internal chamber (14) of the spindle (10), through the peripheral wall (12) and a protective layer (19) of hard chrome having a sandblasted outer surface (18) with an average roughness ranging between 6 and 6.5 ?m, obtained by dry sandblasting.

Abstract: A spindle (10) suitable for winding up coreless rolls (11) of a stretchable plastic film; the spindle (10) comprises a tubular body having a peripheral wall (12) defining at least one internal chamber (14) connectable to a pressurised air source. A plurality of perforations (17) extends from the internal chamber (14) of the spindle (10), through the peripheral wall (12) and a protective layer (19) of hard chrome having a sandblasted outer surface (18) with an average roughness ranging between 6 and 6.5 obtained by dry sandblasting.

Abstract: A method, a mandrel and a device for removing coreless rolls of a plastic film. The mandrel comprises a tubular body having a plurality of radial holes, conformed with a chamber for distributing pressurized air, in which a piston suitable for being magnetically coupled with an external drive member slides. When a roll must be removed, pressurized air is supplied to the fore end of the mandrel, and escapes from all the holes to expand the internal turns of the roll which can be taken off without friction. As the roll advances along the mandrel, the magnetically driven piston progressively reduces the volume of the air chamber preventing at the same time the air to escape from the holes that progressively come to lie on the rear side of the mandrel, with consequent saving of compressed air.

Abstract: One or a plurality of coreless rolls of a stretchable plastic film are wound up on a mandrel (10) having a tubular body; the mandrel (10) comprises at least a fore air chamber (14) and a rear air chamber (15) axially aligned, wherein the peripheral wall (11) of the mandrel (10) comprises a perforated zone (16, 17) in correspondence of each air chamber (14, 15). One or a plurality of coreless rolls (B1, B2) of stretchable plastic film are wound up on the mandrel (10) at said perforated zones (16, 17) and air chambers (14, 15); the roll or rolls (B1, B2) are removed by pushing said roll or rolls along the mandrel (10), by supplying pressurized air initially into all air chambers (14, 15) during a first removal step of the roll or the rolls (B1, B2) and selectively disconnecting each chamber (14, 15) from the pressurized air source, starting from the rear air chamber (15) to the fore air chamber (14) at overcoming of each air chamber (14, 15) by said roll or rolls (B1, B2).

Abstract: A method, a mandrel and a device for removing coreless rolls of a plastic film. The mandrel comprises a tubular body having a plurality of radial holes, conformed with a chamber for distributing pressurised air, in which a piston suitable for being magnetically coupled with an external drive member slides. When a roll must be removed, pressurised air is supplied to the fore end of the mandrel, and escapes from all the holes to expand the internal turns of the roll which can be taken off without friction. As the roll advances along the mandrel, the magnetically driven piston progressively reduces the volume of the air chamber preventing at the same time the air to escape from the holes that progressively come to lie on the rear side of the mandrel, with consequent saving of compressed air.

Abstract: One or a plurality of coreless rolls of a stretchable plastic film are wound up on a mandrel (10) having a tubular body; the mandrel (10) comprises at least a fore air chamber (14) and a rear air chamber (15) axially aligned, wherein the peripheral wall (11) of the mandrel (10) comprises a perforated zone (16, 17) in correspondence of each air chamber (14, 15). One or a plurality of coreless rolls (B1, B2) of stretchable plastic film are wound up on the mandrel (10) at said perforated zones (16, 17) and air chambers (14, 15); the roll or rolls (B1, B2) are removed by pushing said roll or rolls along the mandrel (10), by supplying pressurised air initially into all air chambers (14, 15) during a first removal step of the roll or the rolls (B1, B2) and selectively disconnecting each chamber (14, 15) from the pressurized air source, starting from the rear air chamber (15) to the fore air chamber (14) at overcoming of each air chamber (14, 15) by said roll or rolls (B1, B2).

Abstract: A method and an apparatus for corrugating and winding up rolls of a plastic film. The plastic film is corrugated as it is continuously wound onto a roll, by a film drawing drum conformed with a plurality of longitudinally extending grooves to perform open-end corrugation or folds which extend crosswise the film; the plastic film is corrugated crosswise, causing the same film to penetrate into the grooves of the drawing drum by suction of air through a plurality of suction holes which open out into the grooves of the drum.

Abstract: A coreless roll (12) of a plastic film (10) is directly wound onto a tubular spindle (11); the spindle (11) is provided with an air chamber (11P) having a perforated side wall (11W), which communicate with a pressurised air source (27). At the removal of the roll (12), the inner turns of the roll (12) are radially expanded by feeding a pressurised airflow into the winding spindle (11) and the roll (12); the pressurised air is fed for a length of time required for the removal of the roll (12).

Abstract: A method and an apparatus f or winding careless and soft-core rolls (11), of film materials (10). The film (10) is made to advance, at differentiate speeds (S1, S2), between a first and a second drawing unit (12, 21) making the film (10) to perform a floating loop (19). The film (10) is fed in a controlled way, making it adhere to a grooved corrugating drum (22) by an air jet (29) to corrugate cross corrugations in the film (10) while it is being wound up; the corrugations of the film (10) traps air and prevents the implosion of the roll (11). A programmable electronic unit (32), controls the drawing units (12, 21) in relation to control signals (E1, E2) related to the feeding and winding up speeds (S1, S2) of the film (10), and in relation to a control signal supplied by a sensing device (28) for detecting the position of the floating loop (19).

Abstract: A method and an apparatus for winding coreless and soft-core rolls (11), of film materials (10). The film (10) is made to advance, at differentiate speeds (S1, S2), between a first and a second drawing unit (12, 21) making the film (10) to perform a floating loop (19). The film (10) is fed in a controlled way, making it adhere to a grooved embossing drum (22) by an air jet (29) to emboss cross corrugations in the film (10) while it is being wound up; the corrugations of the film (10) traps air and prevents the implosion of the roll (11). A programmable electronic unit (32), controls the drawing units (12, 21) in relation to control signals (E1, E2) related to the feeding and winding up speeds (S1, S2) of the film (10), and in relation to a control signal supplied by a sensing device (28) for detecting the position of the floating loop (19).

Abstract: A method and an apparatus for corrugating and winding up rolls of a plastic film. The plastic film is corrugated as it is continuously wound onto a roll, by a film drawing drum conformed with a plurality of longitudinally extending grooves to perform open-end corrugation or folds which extend crosswise the film; the plastic film is corrugated crosswise, causing the same film to penetrate into the grooves of the drawing drum by suction of air through a plurality of suction holes which open out into the grooves of the drum.

Abstract: A coreless roll (12) of a plastic film (10) is directly wound onto a tubular spindle (11); the spindle (11) is provided with an air chamber (11P) having a perforated side wall (11W), which communicate with a pressurised air source (27). At the removal of the roll (12), the inner turns of the roll (12) are radially expanded by feeding a pressurised airflow into the winding spindle (11) and the roll (12); the pressurised air is fed for a length of time required for the removal of the roll (12).