GB1257145A - - Google Patents

Abstract

1,257,145. Shrink covering. STERLING MACHINERY PTY. Ltd. 27 July, 1970 [6 Aug., 1969], No. 36208/70. Heading B8C. A method of shrink covering an article or stack of articles 13 comprises covering the article with a loose inverted, heat-shrinkable bag 23, at least partially evacuating the bag to form folds or pleats, and heating the bag to shrink it and weld together the layers of material constituting the folds. As shown, the stack of articles 13 is transported on a pallet 12 by a pair of endless conveyers 11 on to a perforated metal box 16. A suction fan 21 housed in a chamber 20 withdraws air from the bag through an exhaust port 19 in the box 16 thereby producing folds which are manually manipulated to coincide with the upper corners of the stack. A vertically movable hot gas duct 24 surrounds the stack so that hot gas produced by a burner 38 may be directed by duct nozzles 25 on to the bag 23 to produce shrinkage and welding of the fold layers. The duct and burner are carried on rollers 30 and are moved up and down on a vertical frame 28 by an electric motor 31 connected via a worm gear-box 32 to a cross-shaft 33 provided with sprockets 34 engaged with lifting chains 33 provided with counter-weights 37. A centrifugal blower 40 delivering heated gas into the duct 24 may draw make-up air into a plenum chamber 39 through an inlet 41 provided with a flow-rate damper 42. Adjustable, perforated duct plates 43 may be provided to control the gas flow to the nozzles 25. The latter may be partly blanked off with plugs or dampers so that an un-shrunk vertical band for preserving printed matter is left in the bag. A heat shrinkable sheet may be placed between the stack and pallet and welded to the bag 23. The vertical intermittent movement and length of travel of the duct and burner may be automatically controlled. An adjustable dwell is provided at predetermined points, a long dwell being provided at the top and bottom. The bag may be shrunk using radiant heaters, e.g. electric.