Machine for packaging groups of products in a roll

A machine for packaging groups of products in a roll with a sheet of film;

• the machine comprising at least:
• a first station for wrapping with the sheet of film wrapped on four consecutive sides of the group of products in the roll and wherein, for each of two heads of the group of products in the roll, an upper horizontal flap, a lower horizontal flap, a first vertical flap and a second vertical flap protrude;
• a second station for folding the four flaps onto the two heads of the group of products in the roll, having:
• a conveyor surface configured for moving the group of products in the roll partly wound along a feed direction;
• a series of folding devices, positioned on opposite sides of the conveyor surface and configured to fold the corresponding pairs of head flaps, horizontal and vertical, towards the corresponding head of the group of products in the roll during passage of the group of products in the roll;
• the series of folding devices being spaced from each other along the path followed by the group of products on the conveyor surface to allow a predetermined folding sequence of the four flaps for each head;
• a unit for sealing the four folded flaps for each head located downstream of the series of folding devices;
• relative to the feed direction of the group of products in the roll,
• a device for generating a negative fluid pressure for each side of the conveyor surface, positioned at least before the corresponding device for folding each lower horizontal edge of the sheet of film, relative to the feed direction, and configured to obtain, by generating a localised vacuum, a raising, at least partial, of the lower horizontal flap with respect to the conveyor surface to define a pre-folding of the lower horizontal flap;
• wherein each device for generating the negative fluid pressure comprises a bar extending at least parallel to the conveyor surface and at a height higher than the conveyor surface;
• the bar being configured to define a fluid passage duct including a plurality of holes open along an extension thereof and oriented according to a direction opposite to a zone of passage of the group of products in the roll on the conveyor surface;
• a source of fluid being connected to a nozzle of the duct having an internal cross-section configured to create a negative pressure along the entire extension of the duct and therefore through the open holes present, to allow the lifting, at least partly, of the lower horizontal flap;
• wherein the bar comprises an inclined stretch having open holes for generating the negative pressure also above a portion of the device for folding the lower horizontal flap.