Patent GB-589679-A (GB)
Title: Method of vacuum packaging and apparatus therefor
IPC: B67C7/00
Filed: 1945-02-26
Abstract: 589,679. Packing. DEHN, F. B. (Flexible Vacuum Container Corporation). Feb. 26, 1945, No. 4801. [Class 94 (i)] The bags are carried successively under a filling station B, a bag-spreading station C and a vacuum-sealing station D. Filling of bags. The blanks are placed in magazines 133, with their mouths uppermost and lips to the rear, and acted on by a weighted follower plate. Each bag blank is drawn from a magazine By a suction cup 206, Figs. 1 and 10, the lip of a bag, temporarily being held by a plate on the magazine, causing the bag mouth to open. The cups 206 are oscillated by an arm 201 under control of a cam 210 and a return spring 209. Spreading fingers enter the mouth of a bag preparatory to the entry of expanding and shaping members 153, Fig. 10, under control of a cam 230 and levers 225 and 228. A crosshead 152, Fig. 6, driven by rack gear 429, 430, moves downward, and members 153 are forced into a bag. The blank is carried into a mould 239, Fig. 10, on a conveyer unit 132. As the cross - head 152 moves down, a roller on a lever 195, Fig. 1, enters a groove in a cam 200, Fig. 6, to cause a bar 172 to be shifted and act as levers connected to the members 153 to draw members 189, Fig. 7, upwardly, and side-walls members 185, 186 outwardly to expand the blank 11. The cross-head 152 is then retracted. Conveyer chains 130, 131, Fig. 6, are driven by pin and slot mechanism 410, 411, Fig. 1, to shift the moulds, carrying bags, from one station to another. A cam 255, Fig. 1, rotates and acts on linkage to lower each filling spout 242, of station B, and also open a valve in the spout, the spout being raised when the bag is filled. The latter passes to station C. A head 262, Figs. 1 and 15, is lowered and a lever 275 swung to shift a rod 272 lengthwise and cause racks 271 to simultaneously rotate pinions 268, 270. These engage racks 267, 269 to cause bars 263, 264 to move down and spread laterally, through elements 282, each bag mouth to form a slit. After retraction of the spreader bars, a bag is moved to vacuum-sealing station D where a sealing-head 297, Fig. 22, makes a gas-tight contact, through packing, with the face 290, of the mould unit, during the closure of a bag under vacuum. The interior of each head 297, and the inside of a bag 11, is placed under moderate vacuum first, by opening one suction valve, and, after an interval, a second valve is opened to place the head under higher vacuum. Air under pressure then enters each cylinder 322, to force a piston 327 downwards causing gears 373, 374, to rotate and blades 356, 357, to fold over the sides of the bag mouth. Further movement of the blades to a position where they lie in a common plane causes the outer free position of the mouth to be folded upwardly and around a pad 369, preferably of rubber, on the blade 357. Heat is supplied by an element 392 to form a vacuum-tight seal across the mouth of a bag. The driving mechanism 340, for the gears 373, 374, is flexible. After sealing is completed, the head 297 is placed under atmospheric pressure and the filled bag is compacted within its mould. The head 297 is then lifted. The cylinders 322 may be inclined, as in Fig. 1, or vertical. A main drive shaft 289, Fig. 1, is pulleydriven and geared a cross-shaft 231, from which other drives are taken. A frame element 435, Fig. 1 is mounted at the end of the vacuum head 297 and pivots around a cam-shaft 311 so that the head 297 may have vertical movement without disturbing the relationship of the driving parts.