Patent GB-868215-A (GB)
Title: Improvements in or relating to bags or bag-like containers, and to a method and apparatus for their production
Inventor: BONSOR DAVID VICTOR
IPC: B31B19/90
Filed: 1958-04-23
Abstract: 868,215. Making paper and like bags. DICKINSON & CO. Ltd., JOHN. May 7, 1959 [April 23, 1958; Aug. 19, 1958], Nos. 12888/58 and 26600/58. Class 94(2). A bag made at least partially of transparent heat-sealable material, e.g. polythene, has, extending from one wall 11 of the bag, a header 11<SP>1</SP> made of stronger material, e.g. polythenelined paper, which is heat-sealed or adapted to be heat-sealed to the opposite wall 10 of the bag over the edge of which it is folded, Fig. 4, to leave, projecting outwards from the edge, an area of header which can be used to suspend the bag, a hole 17 being made for the purpose, in the header or in a tab extending from the edge thereof. In the embodiment shown the longer wall 11 is heat-sealed to the shorter wall 10 along two sides 12, 13 and across one end 14 and an opening 15 is provided between the other ends. When the bag has been filled through the opening the header is folded down and heat-sealed along the overlapping edges of the wall and header and along the side edges of the header itself or, in a modification, the ends may first be folded over. In various modifications the header is sealed down first and the opposite end of the bag left open for packing and then sealed down ; compartments may be formed by the addition of inner transparent walls, and smaller compartments may be formed by shorter walls ; all the walls may be of transparent material and the header alone of stronger material, heat-sealed to one of the walls, in which case the transparent walls may be formed by folding a single strip of material. For a bag as shown in Figs, 1 and 4 a paper web 50 coated with polythene is folded over to form the header, Fig. 29, and the edges of the polythene and paper webs are welded together along the seam 104, opposite sides of the folded header are welded together along the seam 22 and the two webs are welded together along a transverse seam 96. The weld seam 22 is spaced from the edges of the folded header and the edge of the polythene web so as to leave an open side denoted by 105, i.e. the opening 15, Fig. 2. The means for folding the webs and applying the header bars are shown in Fig. 22. A coated paper web 50 is drawn by rollers 61, 62 from a rail 51 over a folding roller 54 and folding plate 55. Two polythene webs 56, 57 are superposed by a roller 60 on the web 50 as it passes along the folding plate. The folding plate is of known construction and carries a guide bar provided with fold retaining pins and the arrangement is such that as the web 50 is drawn along its marginal edge strip is folded up to the side of the roller 54 and thereafter folded down between the fold retaining pins and the fold plate on to the longitudinal edges of the webs 56, 57. The folded and superimposed webs are drawn between platens 67, 68 on which are co-operating punches or dies and, on the platen 68, heater bars which are adjustable in position to suit various widths of web and, on the other platen 67, anvils to co-operate with the heater bars of the platens. The anvil bars 101, Fig. 24, have inserts 103, e.g. of rubber, and glass cloth resilient coverings 102. The inserts 103 could be replaced by heating elements. A compensating arm 64 operates intermittently to assist momentarily during the punching and welding operation the movement of that part of the web between two rollers 66, 69, being rocked in alternate directions about a fulcrum 65 by a lever 92 connected by a rod 94 to a disc 93 with eccentricity adjustable by a screw 95. One end of the platen 68 can swing around a pivot 87 and the other end is connected by an adjustable rod 88 or a lever 89 actuated by a cam 90 on the same shaft as the disc 93. As soon as a bag length of web has been led between the platens, the platen 68 is swung upwards into welding position and simultaneously the roller 63 is raised and the roller 66 drops, thus taking up the incoming web and allowing a previously welded length of the web to be drawn through rollers 70, 71. After being welded the web is fed between rollers 75, 76 to a severing station 77 in which the bags 78 are cut from the web, being then fed by a roller 79 on to a stacking platform 80. Severance may be along the middle of the welded seam, leaving the adjacent ends closed of the bags thus separated, or alongside the seam, leaving a closed end of one bag adjacent an open end of the next. The transparent web may be in the form of a flat tube, in which case the roller 75 has a cutter (which may be rendered inoperative) to slit a tubular web along the fold line remote from the header strip to provide an opening. The number and disposition of heater bars are varied as required for different modifications in the bag header arrangement.