Unit and method for forming a tube for producing sealed packages starting from a sheet of packaging material

A unit configured to form a tube for producing sealed packages starting from a sheet of packaging material having opening devices pre-applied thereon, the unit comprising:

• at least one guiding assembly configured to interact with the sheet of packaging material to fold it gradually into a tube shape;
• the guiding assembly comprising a plurality of folding rollers delimiting a passage for the sheet of packaging material and each having a lateral wall configured to cooperate in contact with the sheet of packaging material to control the folding thereof;
• the folding rollers comprising at least one folding roller having at least one recess on the lateral wall thereof, the recess defining a through slot passing through the lateral wall and configured to be engaged by the opening devices.

A unit configured to form a tube for producing sealed packages starting from a sheet of packaging material having opening devices pre-applied thereon, the unit comprising:

• at least one guiding assembly configured to interact with the sheet of packaging material to fold it gradually into a tube shape;
• the guiding assembly comprising a plurality of folding rollers delimiting a passage for the sheet of packaging material and each having a lateral wall possessing an outer surface configured to cooperate in contact with the sheet of packaging material to control the folding thereof;
• the plurality of folding rollers comprising at least a first one of the folding rollers in which the lateral wall is configured differently relative to the lateral wall of at least a second one of the folding rollers, the lateral wall of the first one of the folding rollers being configured differently by having at least one recess that is recessed into the outer surface of the lateral wall of the first one of the folding rollers, the recess in the surface of the lateral wall defining a slot configured to be engaged by the opening devices.