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

Method for bonding together up to three layers in a film, which may be made of layers of different materials, comprising the following steps:

• unwinding from a first pay-off unit (2) a first layer (S1) of said film and guiding it into a first spreader/applicator (4) unit designed to apply an adhesive material to one side of said first layer and feeding it to a bonding zone (1);
• unwinding from a second pay-off unit (3) a second layer (S2) of said film and guiding it into a second spreader/applicator unit (5) designed to apply an adhesive material to one side of said second layer and feeding it to the bonding zone (1);
• unwinding from a third pay-off unit (6) a third layer (S3) of said film and feeding it to the bonding zone (1);
• bonding together in said bonding zone at least the first layer (S1) and the third layer (S3) by winding said at least first and third layers over a first bonding calender (18), along a contact arc on the surface of said calender, and pressing said layers by a presser roller (19, 25) which is subject to the action of hydraulic actuator (23, 29);
• taking up the bonded film;
• characterized by determining the breadth of said contact arc by rotating a nip (31) onto which the presser roller (19) is mounted, so as to vary the position of the point of contact between a presser roller (19) and the surface of said bonding calender (18).