| 主权项 |
1. A packaging machine with a compensation device for film printing errors, suitable for forming successive packages from a printed, heat-weldable film supplied from a reel, which comprises: a film unwinder; at least one drive for moving the film forwards; a shaper for folding the film along its center lengthways, thus defining two continuous, opposite bands; a number of welders for joining the two bands at a number of closing areas of the packages at the lower end and side ends thereof; a number of cutters for separating the successive packages before they are moved towards the filling and closing stations; a number of photocells for detecting a number of blemish spots printed onto the film and a compensation device for film printing errors; characterized in that said compensation device comprises the following elements between the drive and the unwinder: two free-rotating guide rollers arranged on a first side of the film trajectory and spaced in the forwards moving direction of the film; a free-rotating drive roller, arranged on a second side of the film trajectory, between the two guide rollers and fixed to an actuation means responsible for moving the same transversally relative to the forward direction of the film, up to a number of positions in which the film defines, between the guide rollers and said drive roller, a loop of variable length, suitable for compensating potential printing errors on the film as it passes through the welders. |
