Device for controlling the unwinding of a plastics film in a packaging machine

摘要

The invention relates to a device for controlling the unwinding of a plastic film in a packaging machine. The film before coming in contact with a conveyor belt for the products to be packaged passes in succession through a pair of dragging rollers and about a floating bar disposed between fixed guide rollers. The drive roller of the pair of rollers is driven by a variable speed motor by way of two alternately activated transmission of different ratio. Two microswitches disposed at different levels cooperate with the floating bar in order to activate one or the other of the transmissions.