Method and machine for automatically gluing a heat shrinkable plastic film onto the bottom of an open box

Apparatus for automatically gluing a heat shrinkable plastic film onto a bottom of a rigid container from a plurality of containers, each container being open at its upper part and having a rectangular or square horizontal section, the apparatus comprising:

• an endless conveyor driven intermittently in a longitudinal direction of advancement, and including a stand-by station at an upstream end part of the conveyor on which containers are successively positioned, and a film application station located downstream from said stand-by station;
• a thermo-plastic film application device located above the film application station for applying a section of thermo-plastic film onto the bottom of each container;
• a glue application device located above the conveyor between the stand-by station and the film application station for projecting glue onto the bottom of each container during advancement between the stand-by station and the film application station;
• means for placing and holding each container in position on the conveyor such that one of the walls of the container is always situated in one and the same vertical and longitudinal plane of reference;
• means for measuring for each container the value of at least one of its height and a transverse dimension at the stand-by station;
• and
• means for setting as a function of the measured value, at least one of the vertical position and the transverse extension of the glue application device and the plastic film application device, such that at least one of conditions a) and b) are satisfied, a) said two devices are as close as possible to an upper edge of each container, and b) the transverse extension of said devices correspond to the transverse dimension of each container.