GB1099522A - Improvements in or relating to packaging machine and method of forming packages - Google Patents

Abstract

1,099,522. Making vacuum-formed packages. ROYAL PACKAGING EQUIPMENT Inc. Feb. 4, 1965, No. 5003/65. Heading B8C. [Also in Division B5] In a modified form of the machine described in Specification 1,059,729, a heat sealable web is fed, heated to prepare it for formation of pockets therein, the pockets being formed in clusters whose walls which intersect centrally provide contiguous pocket corners and a depressed portion at each central intersection opening into all pockets of the cluster; the pockets are filled; a heat sealable cover web is placed over the filled pocket clusters such that a gap is left between the depressed portion and the cover; the cover is heat sealed to the pocket walls except at the depressed portion; the pockets of a cluster are evacuated simultaneously through an orifice provided in the depressed portion; and the heat sealing is completed at each depressed portion. General operation.-As shown in Figs. 1, 1A, the bottom web 26 is gripped at its edges by clamps 25, see Fig. 18, carried on chains 24 and moved intermittently through stations A-J. At station A the web is preheated by a plate 39; at station B a preforming plate 41 further heats the web and shallow draws it by vacuum; at C a mould 76 deep draws the web by vacuum to form a cluster of four pockets including a cruciform depression 84 at the wall intersection, see Fig. 22; at D a holding mould 77, which is movable vertically reciprocably together with mould 76 at each step-motion of the web, receives the cluster and is evacuated to assure retention of the pockets' shape, the pockets then being filled by mechanical or manual means (not detailed). At E, raising of the platform 78 causes a punching sleeve 118, see Fig. 12, to rise and pierce the web at the cruciform depression 84. At this station a cover web 30 is also laid over the filled pockets. At a preliminary sealing station F, sealing bars 123 rise in opposition to seal cushions 124 to seal the cover web 30 to the tops of the wall portions of the clusters, except at the cruciform depression 84. At station G, the pockets are placed in an evacuation chamber having a bottom 168 conforming to the cluster's shape and a top 135, the bottom 168 being vertically reciprocable, see also Fig. 3. The interior of the pockets is evacuated through the orifice in the cruciform depression 84 and simultaneously the chamber is evacuated both above and below the cluster to keep the pockets' shape, and the orifice is then closed by a ring sealer 148 and the chamber 168, 135 vented to atmosphere, whereupon the web portions conform to the shape of the contents. Prior to sealing the orifice, gas may be introduced through a tube 195. At station H a cruciform heat sealer joins the cover web 30 to the cruciform depression 84 when the pockets are raised vertically; at station I, transverse cutters 214, 215 and rotary cutters 216 separate the clusters into individual packages which are then released by the chain clamps 25 to be delivered from the machine. Chain clamps.-As shown in Fig. 18, the clamps 25 differ principally from those of prior Specification 1,059,729 in that a slot 38 is provided in which the web margin is held by the upper jaw 35. Preheating and preforming plate.-Orifices 52 at the corners of shallow pockets 51 allow evacuation, see Fig. 6. The provision of inclined holding shoulders 61 prevents shrink-back of the web being moved to the next station when bi-axially oriented films are used. If the film is not heat shrinkable, these heater pockets are rendered inoperative by filling with metal pieces. Figs. 10, 11 and 13-15 (not shown) illustrate alternative pre-forming pockets. Forming moulds.-As also shown in Figs. 6, 22, see also Figs. 7, 8 (not shown), the vacuum is applied through corner holes 87. The cruciform depression is formed by a depressed planar portion 85 and downwardly sloping depressions 86. Chambering (90) in the mould base conducts cooling water substantially to set the vacuum formed shape. Figs. 13, 14, 16, 17 (not shown) illustrate the provision of filling blocks (103) which lie on the pocket bases whose upper surfaces have depressions according to the shape of the contents so that the pocket bases are thus pre-shaped. Orifice punching.-The orifice puncher 107, see Fig. 12, comprises a stationary plunger 114 over which a cutter sleeve 118 reciprocates, the disc thus being punched out being removed through the tube 117. Evacuation station.-See Fig. 3 and also Figs. 2, 4, 5, 19-21 (not shown). The chamber cover 135 includes reinforcing and pressure applying strips (138), (139). A sylphon bellows 143 serves for applying vacuum above the cover web 30 and around a ring sealer 148 which is electrically heated. An adjustable spring 164 varies the downward pressure exerted. A bore 177 carries an evacuating tube 178 recessed to carry a cushion seal ring 179, and also carries a gassing tube 194. Transverse severing.-As illustrated at I in Fig. 1A and also in Figs. 23-25 (not shown), the cutter 214 is higher than cutter 215 so that it cuts first when both are raised by reciprocating platform 209. This gives the transverse seal lines, normally bent owing to tension, time to straighten out so that distortion of the cut edges is reduced.