GB1104890A - Method and apparatus for mechanically producing string-tied bags - Google Patents

Abstract

1,104,890. Draw string bags. A. MEYER. 2 May, 1966 [8 May, 1965; 12 Jan., 1966], No. 19246/66. Heading B8K. [Also in Divisions B5 and D1] Draw string bags are formed from two superimposed webs, each having a longitudinal hem containing strings by transversely cutting the webs but not the strings to form a bag, which is accelerated forward to separate it from the webs so that the strings therebetween can be severed and knotted. As described, a longitudinal edge 10a, Fig. 1, of a plastics tubular sheet 10 is slit by a blade 13 and the marginal edges folded over to form hems 24, the upper and lower hems containing a pair of strings 17, 18 and 19, 20 respectively. A partial weld (42a, 42b) (Fig. 2, not shown), is formed by a welding bar 26 between each pair of strings and the hems sealed to the sheet 10 at (43a, 43b) by a welding bar 27. The sheet 10, but not the strings, is then transversely sealed and severed by a welding bar 31 to produce a bag 36 which is gripped by an accelerating mechanism 32, driven at a higher speed than the preceding sheet 10 in order to draw out the strings between the bags 36. Finally, the strings between the bags 36 are cut at 37 and subsequently knotted. The strings 18, 20 and 17, 19 (Fig. 2, not shown), may be knotted to each other by the apparatus illustrated in Fig. 4. The pair of strings 162 are drawn apart between adjacent bags on a conveyer belt 161 passing between guide rollers 159 and 160 (not shown on the left-hand side of the Figure). On the movement of a driving lever 112 in the direction g, the guide rollers 159 and 160 are moved to cause the strings 162 to be lowered on to projections 132 of slide members 123 and 124, into slots 146 of string guides 145 and on to the recesses 148a and 149a of tying tongs 148 and 149. The strings 162 are clamped on a support 111 by brackets 119 and 120, between which they are cut by a blade 121. During the further movement of the lever 112, the slide members 123 and 124 are moved forward by disengagement of pawls 137 and 138 so as to tightly clamp the strings (Fig. 5, not shown), whereupon the tying tongs 148 and 149 are rotated by a worm shaft 150 to form a loop (168) in the strings 162 (Figs. 6 to 8, not shown). Finally, the loop (168) is pushed off the tong by an ejector arm 174 thereby forming a knot.