Abstract: The automatic machine comprises a magazine, dispensing die-cuts pre-creased longitudinally with fold lines providing divisions between at least four side panels and a securing flap, suckers by which the die-cuts are picked up from the magazine, and a revolver with radial grippers. In addition, use is made of a conveyor by which the die-cut is transferred forcibly from the suckers to the revolver and bent into U-shape at the same time, and the jaws of each gripper incorporate suction passages emerging along the edges parallel to and farthest from the axis of rotation of the revolver, which firmly withstand the action of first and second folders used to press down the securing flap and the end panel; thus, the die-cut is positively handled and conveyed during its entire passage through the machine.