Machine for bonding films made of different materials in several layers, and the corresponding method

Machine for bonding up to three layers in a film, which may be made of layers of different materials, comprising:

• a first pay-off unit (2) designed to unwind a first layer of said film, said first pay-off unit comprising a first reel (8) associated with a spreader/applicator unit (4) to apply an adhesive material to one surface of said first layer;
• a second pay-off unit (3) designed to unwind a second layer of said film, said second pay-off unit comprising a second reel (15) associated with a spreader/applicator unit (5) to apply an adhesive material to one surface of said second layer;
• a third pay-off unit (6) designed to unwind a third layer of said film, said third pay-off unit comprising a third reel (37);
• and
• a bonding zone (1) designed to join the various layers of film together;
• and
• a winding unit comprising a reel (35) onto which the bonded film is wound,
• said bonding zone (1) comprising at least one bonding unit (16, 17), said bonding unit being provided with a bonding calender (18, 24) onto which the various layers of film are wound overlapped around a contact arc, at least one presser roller (19, 25) which press the layers on the calender after said contact arc to complete the bonding, the position of said presser roller determining the breadth of said contact arc,
• said pressing roller being fitted with at least an hydraulic actuator (23, 29) which brings it in contact with the layers of film on the bonding calender, and
• said presser roller (19) and the hydraulic actuator (23) being mounted on a nip rotating around the axis of the bonding calender (18) so as to vary the position of the point of contact between the presser roller and the calender and hence to vary the breadth of the contact arc, along the surface of the calender, in which the layers are overlapped.