Patent GB-568520-A (GB)
Title: Means and methods for hermetic bag and tube closure
IPC: B65B51/02
Filed: 1943-09-27
Abstract: <PICT:0568520/IV/1> <PICT:0568520/IV/2> <PICT:0568520/IV/3> <PICT:0568520/IV/4> <PICT:0568520/IV/5> <PICT:0568520/IV/6> <PICT:0568520/IV/7> To seal hermetically the ends of tubular bags or liners such as are used for packing food &c. either before or after receiving the contents, the opposite walls of the ends of the liners are pressed together along a line spaced from the end of the liner, the walls are then separated beyond the line of pressure and a sealing medium such as a thermo plastic adhesive is introduced into the space between the ends which are opened out and sealing is then effected by pressure devices which may be shaped to form a bead. In dealing with a tube or liner 1, Fig. 4, formed with an overlapping side seam, the tube is carried through a machine, Fig. 23, by grippers on conveying chains 5a, 6a, and by means of a guide plate 14 the tube is bent around a hold-down bar 13 to form a line of pressure, and the end is then turned into a vertical position as shown in Fig. 4 by passage between plates 14a, 15. The ends 1a are then opened out by means of an air blast, or by means of oscillating suction devices engaging the outer ends, or by means of friction devices having a differential action upon the outer ends.  A plastic adhesive is then introduced between the opened-out ends by means of a nozzle 17 supplied from a heated reservoir 95, Fig. 23, under control of a valve 98 operated from a cam 103 on a shaft driven by bevel gears which also drives a cam 90 which operates a lever 84 adapted to raise and lower a carrier 82 in which the nozzle 17 is mounted.  The nozzle 17 is also oscillated by rack-and-pinion mechanism actuated by a cam 108 so as to cause it to be inclined first in the forward direction as shown at 17a, 17b, Fig. 7, to apply adhesive to the raised side, and finally to the reverse direction.  The ends 1a are now pressed together so as to spread the adhesive by segmental rollers 21, 22, Figs. 11 and 23, provided with grooves adapted to form a head 25 of adhesive.  Beads 27, 28, Fig. 13 (not shown) are also produced and ensure a completely hermetic seal.  The rollers 21, 22 may be replaced by grooved blocks carried by chains slightly separated at one end but converging at the other so as to cause the blocks to engage the ends 1a and form a bead of adhesive.  The liners may be formed with heat-sealable coatings, or may be formed of non-heat sealable amorphous films, glassine, or parchment, and the thermoplastic cement may be of a water-proof or grease-proof character.  Compositions of the former class may comprise resins, e.g. wood resin, or terpine resin mixed with hydrocarbon polymers such as polybutine.  The latter class may comprise 60 per cent of a polyvinyl acetate resin, 20 per cent di-butylphthalate, and 20 per cent of a hydrogenated resin, or 20 per cent wood resin or 20 per cent shellax.  For closing liners of bag tube form attached to cartons either after the cartons are filled or preparatory thereto a modification of the above process is employed in which spread fingers 123, 124, Fig. 30, are moved into the end 1b of a liner and opened out so as to elongate the mouth of the liner and then a pair of rods 125 are moved to hold the mouth in this elongated position.  A pair of presser members 126, 127, Fig. 32, suspended by arms 128, 129 are then brought to bear against the flattened mouth and pinch it together along a line interspaced from the end as shown in Fig. 34. Oscillating suction members 130, 131 then engage the sides of the mouth and open it out.  A nozzle 17 then introduces adhesive as in the first modification and the presser members 126, 127 are then moved into contact to press the open ends together, and grooves 133 in the presser members form a bead of adhesive as in the first modification.  The operations outlined above may be carried out in a packing-machine as described in Specification 549,632, [Group XVII], prior to the closing down of the flaps of the cartons.