Patent GB-1204940-A (GB)
Title: Method of incorporating a cutter in overwrapped packages and related apparatus
Inventor: FORMAN HAROLD MORTON
IPC: B31B1/90
Filed: 1968-12-30
Abstract: 1,204,940. Packaging. H. M. FORMAN. 30 Dec., 1968 [16 Jan., 1968], No. 61655/68. Heading B8C.  A method of positioning a flexible tear string 16 about an article 11 to be overwrapped with flexible film 12 such as " Cellophane " (Registered Trade Mark), polyvinyl chloride, or a polyester, comprises the steps of forming a package site between two layers of film in a generally horizontal plane, providing a length of flexible string, consisting of e.g. a strand, filament, wire group of filaments, ribbon or tape of textile, metal or plastics, the distal end of which is grasped within the site and the proximal end of which is stored for free release remote from the site, placing into the site, in contact with an intermediate portion of the string, an article to be overwrapped with film, advancing the article and the site a predetermined distance along the horizontal plane with respect to both the grasped distal end and stored proximal end of the string whereby a predetermined length of string is paid out about the article, releasing the distal end of the string, grasping a new intermediate portion of the string located between the article and the stored portion, and severing the string between the newly grasped portion and the item whereby the newly grasped portion becomes the distal end of the string and the article within the packaging site has a predetermined length of string wrapped thereabout. The string may extend through a heat sealed edge 13 of the film and the ends 14, 15 may be spaced apart, the film being heat shrunk; alternatively the end 14 may be anchored within the confines of the package. As shown, the packaging machine includes a sealing frame 26 having a heating wire 28 and pivotally mounted on a shaft 27 to abut an anvil 29, and a conveyer 24. The packaging site consists of the centre fold between two layers 32, 34 of film drawn from a roll 31 and a heat-sealed edge formed from a previous cycle of operation, the layer 34 passing beneath the lower plate 43 of a housing 40. The tear string is supplied from a spool 48 and passes through a wand 49 which is movable by a motor 51 between an upper and lower position. The end 75 of the string issuing from the wand is grasped between a bumper 52 and a snubber 57 mounted between the housing plates 42, 43 and adjacent which is a cutting anvil 61 cooperable with a knife edge 62. The motor 51 may be dispensed with when the wand is counterbalanced by a weight. In operation, the end 75 of the string being grasped between the bumper and snubber, the article 11 to be wrapped is advanced together with a length of string therearound on to the conveyer 24, the string being released by operation of a motor 64 which tensions a cable 65 to move an arm 59 which, in turn, moves through a screw 66 the arm 55 carrying the snubber, after which the sealing frame 26 descends to seal the two open edges of the package and simultaneously forms a pocket constituting the packaging site for the next article. Upon cease of operation of motor 64 to release the tension in the cable 65, springs 58, 63 restore arms 55, 59 to the original positions thereof whereby the string is again grasped and cut. A hook or projection 67, spanning the gap between the anvil 61 and knife edge 62 displaces the cut end of the string. The latter is preferably of cotton or polyvinyl chloride and may be moistened with a liquid size prior to positioning about the article.