Patent GB-1456718-A (GB)
Title: Process and machine for wrapping and packaging tray-like recep tacles in stretchable foil plastics material
IPC: B65B45/00
Filed: 1974-09-20
Abstract: 1456718 Wrapping article-containing, traylike receptacles AMPAGLAS SpA 20 Sept 1974 [5 Oct 1973] 41081/74 Heading B8C In a process for wrapping and packaging a tray-like receptacle 1 containing a generally irregularly shaped article in a foil sheet 7 of stretchable plastics material, which receptacle has a flat bottom shallowly recessed from a low, outwardly-curved rim, said process comprises the steps of a positioning the receptacle on a support 2 at a wrapping location; b unreeling a section of a continuous foil web 7 from a storage roll 8 under evenly distributed tensile stress by gripping the leading edge of the foil and translating the foil section to said wrapping location in a direction normal to the leading edge proximate the supported receptacle; c stretching the foil section by a predetermined amount in at least the dimension transverse to the unreeling direction from the locations at opposite sides of said support receptacle; d longitudinally holding fast the transversely stretched foil section while severing said section from said storage roll to form a sheet from said foil section; e bringing the article-containing receptacle into contact with the stretched foil sheet while folding the longitudinally extending edges of the transversely-stretched sheet over the rim and on to the bottom surface of said receptacle and simultaneously reducing the transverse tension effected by said stretching in order to maintain the predetermined amount of stretching in said foil; f folding the leading and trailing edges of said foil sheet over the rim and on to the bottom surface of the receptacle; and g welding the leading, trailing, and longitudinally extending edge of said bottom surface. After a tray 1 has been fed by a conveyer, not shown, on to the lifting table 2, initially in a position lower than that shown in Fig. 1, the unreeling clamp 9 moves forward toward a slide bar 21 of the foil-gripping-andsevering device 13 while cutters 17, 18 and grippers 19, 20 thereof are in their open, inoperative, positions. At the end of its forward stroke -the clamp 9, which comprises a single lower element 54 and three upper elements 51, 52, 53 elastically hinged thereto, is opened and closed to grip the leading end 7<SP>1</SP> of the foil and then move backwardly to draw a length of foil, under tension from the roll 8, until it reaches its initial position shown in Fig. 1. At this moment the side clamps 10, 11, each with a pair of gripping elements 40, 41 elastically hinged together, grip the sides of the foil and move away from each other to stretch the foil transversely, e.g. by an amount between 22 and 30% of its width. The elements 19, 20 of the clamping device 13 then close to restrain the foil while the blades 17, 18 sever and cut a foil sheet from a web, simultaneously the table 2 and tray 1 begin to move upwardly toward the sheet which is held fast at both ends and at both sides. When the tray 1 reaches its uppermost position, to project into the web, the side clamps 10, 11 move towards each other as the outermost clamping elements 51, 53, as well as the outermost among gripping elements 19, 20, are released so that the opposed side edges of the foil are folded under the tray 2, which is then supported by the elements 40 while the lifting plate 2 is returned to its lowered position. The clamp 9, still gripping the central area of the foil by means of the elements 52, 59, is displaced toward the tray 1, the clamp being released when a clamp upper part 55 passes beneath the tray 1 to fold the leading end 7 of the foil sheet under the tray to adhere to the folded under side portions of the foil as the clamps 10, 11 are returned to their outer positions, the tray 2 being supported by the part 55. In order to complete the wrapping the trailing end 711 of the sheet is released by the centrally located gripping elements 19, 20 whilst thrusting element 12, Fig. 1, pushes the tray 1 off the part 55 and on to an output platform 60, Fig. 5, to fold the trailing foil end 7<SP>11</SP>, the folded edges of the foil being welded together beneath the tray by a suitably located heated area of the platform 60. The inner surfaces of the clamps 51-54 and 40, 41 are lined with resilient material.