GB1421977A - Methods of and devices for continuously wrapping collections of articles in thermo-shrinkable plastics film - Google Patents

Abstract

1421977 Shrink-wrapping apparatus; endless chain conveyers LARA SA 31 Aug 1973 [4 Sept 1972 25 Sept 1972] 41102/72 Headings B8C and B8A [Also in Division B5] In a shrink-wrapping apparatus wherein articles or collections of articles P are loosely wrapped in heat-shrinkable plastics films 12, 14 supplied from upper and lower reel handling devices 13, 15, the wrappers are heat-shrunk as the wrapped articles P are conveyed along an ascending path and are cooled during conveyance along a descending path. In operation articles P are transferred from a conveyer 16 by a pusher 17 on to a fixed feed fork FC to overlie the lower plastics film 12 and to be picked-up with the plastics film 12 by a respective one of a plurality of trays 2, each of which is articulated between opposed conveyer chains 1. As each article P is pick-up by a tray 2, a loop forming device 10 forms an upwardly directed loop 11 of slack film between successive articles P. The trays 2 convey the articles into a wall of film constituted by the lower and upper films 12, 14 welded together at their ends. The upper film 14, thus drawn over an article P, and the loop 11 of lower film 12 are then welded and severed behind each article by welding and severing jaws 36, 37 which are movable towards and away from each other along an oscillating arm 35. The loosely wrapped articles are conveyed through a heat-shrink tunnel having a horizontal preheating zone Z1, an ascending heat shrinking zone Z2 and a horizontal upper finishing zone Z3. The hot air in the zones Z1, Z2 and in the zone Z3 is re-cycled by respective blower and suction assemblies 24, 28 which withdraw the hot air from the ceilings of the zones Z2, Z3 via ducts 129, 132 and introduce it into chambers which contain lateral groups of finned resistance heaters and have perforations through which the hot air is introduced to the zones Z1, Z2, Z3. A cooling assembly 32 above the descending path feeds jets of cold air on to the heat-shrunk wrapped articles which are eventually deposited on a fixed discharge fork FD. Each tray carries a pair of rollers G1 at its rear end and two pairs of rollers G, G mounted on the ends of crank arms which are fixed at their opposite ends to a rod by which the tray is articulated to the chains 1. The rollers G and G1 co-operate with rails throughout the conveyer path to maintain the trays in a horizontal condition.