GB1333125A - Machines for placing envelopes over objects to be packaged - Google Patents

Abstract

1333125 Shrink wrapping SOC D'APPLICATIONS THERMIQUES SA 9 Dec 1971 57163/71 Heading B8C A machine for forming an envelope around an object 2 comprises a roller 5 for delivering a sleeve 27 of material in flat form with opposite inwardly directed folds 28, 29, a wedge 26 for engaging with the folds and temporarily separating edges of the sleeve adjacent the folds, gripping means, e.g. clamps 16, for gripping the edges of the sleeve and being carried by endless chains 12 having a first run 14 which carries the gripping means and sleeve towards the object, and a second run 11 along which the gripping means and the sleeve separate to provide an open end of the sleeve facing the object, fingers 45 adapted to penetrate the open sleeve and to be moved outwardly thereof, the fingers being mounted on second endless chains 41 and means for welding and cutting the sleeve to form a closed end and located along the first run of the first endless chain downstream of the separating wedge. As shown, the flattened sleeve material is fed to wedges 26 which open up the folds 28, 29 to allow pairs.of clamps 16 to grip edges 30- 33 of the sleeve. The clamps 16 which are carried by two double runs of endless chains 12 running over sprockets 7, 8, 9, each comprises a movable jaw 17, Fig. 6, fixed to a shaft 18 running in a bush 19 fixed to a stationary jaw 20. As a clamp passes along a run 13, an arm 21 contacts a roller 34 to rotate the clamp jaw 17 which stresses a clamp spring 22 in torsion and moves a pin 25 into alignment with a hole 24 in the jaw 20 into which it gradually enters as a tappet 18a on the shaft 18 travels along a ramp 35. As the sleeve, gripped at edges 30-33 by the clamps 16, reaches the sprockets 8, the opposed clamps are carried along the runs 11 to ramps 36 which release the clamps from the sleeve which then falls towards the load 2 to be packaged. Fingers 45 are then retracted from a 45a position to hold the sleeve around the load as the fingers 45 are lowered by chain runs 41. When the required length of sleeve has been unreeled, the chains carrying the clamps 16 and fingers 45 stop and the sleeve is welded and severed by pivotable jaws 39, 40, after which the clamps 16 and fingers 45 move the sleeve to the position in which the welded seam is at the same level as the sprockets 8 at which the clamps 16 are released by bars 46 and the fingers slide out of the bottom of the sleeve. The machine may be semi- or fully-automatically operated. In another arrangement, Figs. 7 to 12 (not shown), the sleeve is supported over the load by fingers on a frame (52) which follow the contour of the load and enable the sleeve to be heat shrunk inside the machine without removing the load, by providing heating elements which are switched on when the frame moves upwards from the bottom of the load. In a modification (not shown) sliders (56) which guide the frame 52, are replaced by outlets of compressed air lines which form cushions between the frame and load, and which may be used as heated air outlets for shrinking the sleeve about the load.