Patent ID: 7784252
Filing Date: 2010-08-31
Classification: B65B

Abstract:
1. A unit for positioning a sheet of film to cover the tops of product groups, the unit being associated with an apparatus for wrapping the product groups with film and comprising a frame mounting at least one carriage that moves relative to the group of products to be wrapped with the film to define a wrapping area, said carriage mounting at least one first roll of film; the frame also mounting one positioning unit comprising at least: a second, horizontally positioned roll of film; a first carriage slidably mounted, on both sides, on guide rails running along an upper horizontal plane and driven in both directions along the wrapping area by a driving unit; the first carriage being equipped with a first gripper unit designed to grip the free end of the film and to unwind the film for a predetermined length dependent on the size of the product group; a film cutter located in the vicinity of the second roll and designed to separate the length of film thus unwound from the rest of the film to define the sheet, wherein the unit comprises: a second carriage slidably mounted on the guide rails opposite the first carriage and in the vicinity of the film cutter; a second gripper unit mounted on the second carriage, acting on the film in such a way as to hold the sheet at a second retention point when the film cutter are activated; means for coupling the second carriage to the driving unit in such a way that, when engaged, the two carriages move together as one in order to position the sheet centrally on the top surface of the product group to be covered; the second carriage being equipped with a supporting unit for supporting the passing film while it is being unwound by the first carriage; the second gripper unit comprising at least one pair of supporting unit, each comprising contact plates associated with the second carriage and having an L-shaped portion protruding downwardly under the second carriage in such a way that its horizontal section supports the longitudinal edge film being unwound, a pair of vertical actuating pressers positioned on the second carriage in the vicinity of the plates in such a way as to face the horizontal section of the shaped portion, and mobile between an idle position where a working head of the rod is away from the horizontal section and a working position where the working head stops the film between the head and the horizontal section of the plate.