Packing unit and method for folding a blank on a packing machine

11) A packing method for folding a blank (4) on a packing machine (1);

• the packing method comprising the steps of:
• feeding a packing conveyor (17), having at least one pocket (18) for receiving the blank (4) along a packing path (P);
• and
• inserting the blank (4) into the pocket (18) on the packing conveyor (17) by means of a feed device (19);
• the packing conveyor (17) comprising:
• at least a first conveyor belt (23), and at least a second conveyor belt (24) separate from parallel to, and alongside the first conveyor belt (23), said first (23) and second (24) conveyor belts defining a bottom wall of the pocket (18);
• a first retaining member (25), which projects perpendicularly from the first conveyor belt (23) and defines a front wall of the pocket (18) in the direction. of the packing path (P);
• and a second retaining member (26), which projects perpendicularly from the second conveyor belt and defines a rear wall of the pocket (18) in the direction of the packing path (P);
• the distance between said first retaining member (25) and said second. retaining member (26) defining the length (L) of said pocket (18) in the direction of the packing path (P);
• the packing method being characterized in that the feed device (19) comprises:
• a first suction pickup head (21), which engages a first panel (11) of the blank (4) inside a store (20);
• and a second suction pickup head (22), which engages a second panel (13) of the blank (4) inside the store (20);
• and the method comprises the further step of moving the pickup heads (21, 22), by means of appropriate actuating devices (33, 34), from a withdrawal position at the store (20) to a release position at the packing conveyor (17), to insert the blank (4) inside the pocket (18) on the packing conveyor (17), and then release the blank (4), folded into inside the pocket (18) on the packing conveyor (17);
• said length (L) being variable according to the format of said blank (4);
• and said actuating devices (33, 34) altering the distance between said pickup heads (21, 22) and said packing unit at said store (20) according to the format of said blank (4).