Patent GB-1203096-A (GB)
Title: Process and apparatus for the manufacture of multi-ply bag-forming stock and bags therefrom
IPC: B31B39/00
Filed: 1967-09-28
Abstract: 1,203,096. Making flat multi-ply tubing for bag making. HOERNER WALDORF CORP. 28 Sept., 1967 [28 Sept., 1966], No. 44265/67. Addition to 1,149,363. Heading F2P. Bag-forming stock, which is later made into bags by known methods of cutting and gluing or welding, is in the form of a continuous gusseted tube of multi-ply material made by a process which involves the following steps: (a) at least one paper or like web 35 (two, as shown) is advanced to form the outer ply or plies of the stock, (b) a preformed tube of plastics material 44 made by any known method, i.e. seamless or formed by longitudinally welding a sheet formed into a tube, is advanced to form an inner plastic liner of the bag, (c) a portion of the plastic tube 44 is maintained inflated with a gas, e.g. as shown by trapping air in it between exit rollers 47 and entry rollers (not shown), (d) a part of the inflated portion of the tube 44 is flattened, as shown by converging upper and lower pairs of plates 23, 25 of a mandrel assembly 22, (e) the webs 35 are infolded, as by the rollers 41 and a pair of further rollers carried on adjustable supports 38, to form a partially flattened tube around the partially flattened portion of the plastic tube 44, (f) contact is established between the inner and outer tubes at oppositely disposed longitudinally extending areas while the tubes are maintained separate in the remaining area, e.g. as shown by a pair of gusset-forming plates 39 extending into the space between the upper and lower plates of the mandrel, (g) a gusset is formed in both tubes simultaneously, e.g. by progressively increasing the depth of penetration of the gusset-forming plates into the above-mentioned space towards their trailing ends, and (6) the gusseted tube is flattened, as shown by the exit rollers 47 to complete the formation of the gusseted multiply stock. Preferably the webs are passed through pasting rollers which both paste the longitudinal edges, which overlap when the webs are formed into a tube, and add a row of transverse paste spots at the desired intervals where, after subsequent cutting, one end of each bag is to be closed. The bags may be closed at one end after cutting by stitching instead of by gluing. In either case heat is subsequently applied to seal the plastic inner liner at the closed end of each bag. The apparatus shown is adapted for adjustment to vary the size of bags produced. For this purpose the mandrel, Fig. 3, has upper and lower fillet plate 31, 27 which provide the plastic tube engaging surfaces of the mandrel and which bridge the respective pairs of plates 23, 25, to which they are adjustably secured by straps 29 and bolts 30. This allows the plates of each pair 23, 25 to be moved towards and away from one another to vary the total width of the mandrel. This is effected by securing the plates, by their leading ends only, to respective pairs of arms 19, 20, the former being located by additional arms 21, one arm of each pair being secured to a slide block 16 and the other to another slide block (16a, Fig. 1, not shown), the two slide blocks being supported on a pair of transverse tubes 15, 15a and having threaded apertures engaging opposite handed portions of a rotatable threaded rod disposed between the tubes 15, 15a and rotatable by a hand wheel (52, Fig. 1) to effect adjustment of the width of the mandrel. The upper and lower outer surfaces of the mandrel which engage the webs are formed by series of straps 34, so that crosspaste spots (see above) are not wiped off as the webs are folded about the mandrel. Both the mountings for the rollers 41, which are inclined to the direction of movement, and those of the gusset plates 39, are adjustable by means of slotted brackets (42, 40, respectively, Fig. 1, not shown).