Patent GB-676047-A (GB)
Title: An improved method of and means for producing machine-made bag tubes with longitudinal gusset folds and tubular bags with gusset-folded sides
Inventor: RANDALL JOHN WILLIAM
IPC: B31B23/00
Filed: 1950-05-23
Abstract: 676,047. Making paper bags. DICKINSON & Co., Ltd., J. May 23, 1950, No. 12937/50. Class 94(ii) In a machine for making automatically either a bag tube or a completed satchel bag with longitudinal gusset folds, a web W, Fig. 1, of material drawn from a roll R by co-operating pairs of rollers 16, 17 and 18, 19 has adhesive applied to it transversely at bag length intervals by an applicator 1 and along a longitudinal seaming edge by an applicator 2, and is then passed below roller 4 to a first folding-section 5 which folds the material inwardly along two parallel lines 14, Fig. 10, and over the central longitudinal portion 14a to form the first folds of the gusset, whereupon the web passes over a roller 6 and under a forming-roller 7 which deflects the longitudinal edges outwardly before they enter a fold-forming device 8 which completes the gusset folds 24 and 28. In the example the adhesive applicator 1 applies transverse stripes 38 of adhesive upon the portions of the web that eventually form the bottom crease folds of completed bags and also applies diagonal stripes 39 and triangular patches 40 on the surfaces that form the bottom of the bag. The forming-roller 4 is mounted to rotate freely adjacent to the guide-plates 20, 21, Fig. 2, of the folding-section 5, and has a concave peripheral surface which, in conjunction with a convex web-supporting plate 12, provides a curved throat 13 of restricted height and of a width approximately equal to that of a formed bag tube. The outer peripheral edges 4a of the roller 4 define the fold lines 14 and initiate the upward folding deflection of the longitudinal margins of the web. The guide plates 20, 21 are mounted with lateral adjustment on the plate 12 and have lower guiding edges 22 which form a straight parallel pasage of the width of a bag tube, while the upstanding walls 20a, 21a of the guide plates are each given a helical curvature through an angle of about 150 degrees, and finally twist inwardly just above the plate 12 in completing the first gusset fold, Fig. 7 (not shown). The roller 6 presses the web as it passes to roller 7, which has a cylindrical peripheral surface with defined edges and serve to deflect or fold back the longitudinal margins of the web to form the inner r longitudinal fold edges of the gusset folds 24, while the peripheral end edges of this roller serve to define the outer fold edges 28 of the second gusset folds 27 and the marginal portions of the web which together constitute the rear face of the formed bag tube. Roller 7 may be freely rotatable, and removable for replacement by a roller of different width. Both rollers 4 and 7 may be provided with one or more slots or clearances to avoid contacting with the adhesive coated areas of the web, or their circumference may be of the length of a bag tube, or a multiple thereof. The second fold forming section 8 comprises a web-supporting plate 29 extending from the bottom of the roller 7 and carrying a pair of parallel, laterally adjustable, side guides 30, 31, Fig. 8, carrying flap-folding plates 32, 33 with inner longitudinal edges which are shaped or cut away, as shown, and extend inwardly across the web-guiding passage between the members 30, 31. The folding plates 32, 33 may be flat, as shown, or curved in the manner of ploughshares. Upon leaving the direction-breaking roller 9 and feed rollers the bag tube receives external fold-securing stripes of adhesive applied transversly at bag-length intervals in known manner, the bag-forming lengths are severed, and the bottom ends folded over to complete the bags. Instead of the stationary curved guide plates for the edges of the web, rollers or belts may be employed, and the freely rotatable guiding rollers 4 and 7 may be replaced by intermittently rotatable rollers or non- rotatable members which are displaced periodically.