GB1203868A - Method and machine for forming and filling bags - Google Patents

Abstract

1,203,868. Making bag tubes. RIEGAL PAPER CORP. 29 Nov., 1988 [8 Dec., 1967], No. 56646/68. Heading B5D. [Also in Division B8] A machine for forming packages from a continuous web 10 of flexible material comprises first mechanism for advancing the web with continuous motion along a predetermined path through a coating station, means in said coating station 29 and operable in timed relation with the advance of the web for applying adhesive to the web in a preselected pattern, a package former 97 located downstream from said coating station for receiving the web and for folding the web longitudinally with the opposite edge portions of the web disposed in face-to-face relation, second mechanism for advancing the folded web intermittently through steps of equal length into sealing and severing stations 21, 23 with dwells between successive steps, a sealing unit disposed in said sealing station and operable during successive dwells of the folded web to press against the web to activate said adhesive and form a series of packages 11 connected by cross-seals spaced along and extending crosswise of the web, a cutter disposed in said severing station and movable while the web is dwelling to cut through the web along said cross-seals thereby to separate the web into a series of individual packages each having one open end, a compensator located between said coating and sealing stations for accumulating and tensioning any continuously moving web advanced by said first mechanism while said folded web is dwelling during operation of said sealing unit and said cutter, means for gripping each of the packages and advancing the same in spaced relation through a filling station 25, a dispenser in said filling station for depositing a charge of product into each package through the open end thereof, and means downstream of said dispenser for closing the open ends of said packages. As shown, the flexible web 10, Fig. 2a, of metallic foil, plastics or paper is drawn from a supply roll 19 and across driven rollers 27 to a coating station 29 where the web is pressed by a roller 43 on to a drum 30 rotatable in a trough 31 of a hot melt adhesive, the drum having in the surface thereof a pair of spaced axially extending grooves and at one end a circumferential groove so that stripes of adhesive 39, 40 and 41, Fig. 5, are applied to the web. To advance the web continuously across the drum 30 and at a speed correlated with a subsequent intermittent advance of the web two feed rollers 46, 47 are rotated continuously at a rate determined by the length of web advanced during each intermittent step and by the time elapsing during a cycle by a step and a dwell, the rollers being rotated by an electric motor 49 acting through a reduction gearing 50 connected to a gearbox 53 in turn connected to a variable speed differential 57 driving by one output 60, through an electrically-actuated clutch, and brake units, the roller 46 which drives, through pinions 64, the roller 47. A second output 69 of the differential is connected to the drum 30 which rotates the pinch roller 43, a drive responsive to rotation of the drum being utilized for rotating guide rollers 27, 44. After initially adjusting the speed of the rollers 46, 47 by manual control 73 and at a rate compatible with the intermittent advance of the web, signals are received by a comparator 75 which transmits an error signal to a control 78a on the differential to advance or retard the rotational rate of the differential output 60 and the rollers 46, 47 if the speed of the web becomes slower or faster than required. To accumulate and tension the web advanced continuously by the feed rollers, compensators 79, 80 located at the point of transition from continuous to intermittent motion store the web during each dwell while maintaining tension on the web. Formation of the web into a tube 20 is achieved by a bag former 97 comprising a rotatable forming wheel 99 which depresses the centre portion of the web to dish the opposite edge portions upwardly, the centre portion moving beneath a forming plate 103 and the edge portions being folded around the plate and toward each other by rollers 113 so that the adhesive strip 39 is folded over the opposite edge to form the seam 16, the strips 40, 41 being located on the inner surface of the tube. An electrically-heated sealing bar 116 activates the strip 39 to seal the overlapping edges of the web and the seal is hardened by a cooling bar 120. Upon completion of the seam 16, the tube is advanced off the forming plate 103 and dwells at successive intervals beneath longitudinally adjustable heated, cross-sealing and cooling bars 131, 133 and to complete the bottom seals 18 of the bags 11. The bars 116, 120, 131 and 133 are operated by pneumatic rams the flow of pressurized air to which is governed by electrically-operated valves operated by cams 123. Advance of the tube 20 step-by-step past the former 97 and through the sealing station 21 is effected by feed rolls 136, 137 rotated intermittently to feed the tube in steps equal in length to the length of the bags 11. Drive for these feed rolls is by the motor 49 and from a shaft 156 connected to a shaft 157 the continuous rotary motion of which is converted to intermittent rotation of the feed rolls by a crank 160 connected by a rod 161 to a crank 163 on a shaft 164 coupled through an electromagnetic clutch 167 and bevel gears 175, 177, to the shaft 139 of the roller 136, the motion of which is transmitted to the roller 137 by pinions 179; energization of the clutch is effected by a cam 180 on shaft 124 and operable to open and close a switch 181 in the clutch control circuit. The light beam from a photo-electric scanner is intercepted by one of a series of targets preprinted on the seam 16 so that a signal completes a circuit energizing an electromagnetic brake 186 which abruptly arrests rotation of the feed rolls upon completion of a step of given length. After energization of the brake and stopping of the feed rolls a switch 187 is opened by a cam 189 on shaft 124 to de-energize the clutch and brake simultaneously. The rod 161 completes a downward or active stroke and then starts through an upward stroke to turn the shaft 164 in the opposite direction, a clutch connected to the gearing 177 preventing reverse rotation of the rolls. For bags of different lengths the throw of the crank 160 and angular relation of cams 180, 189 are adjusted as necessary. At a cutting station 23, the tube 20 is separated into open-ended bags 11 by a blade operated by a pneumatic actuator to co-operate with a fixed blade whereby the tube is cut between the adhesive strips 40, 41 the blades being mounted with the feed rolls 136, 137 as a unit which is adjustable along the feed path of the tube according to the length of the bags. Each bag 11 is turned into an upright position and advanced step-by-step through a filling station 25 by an endless chain conveyer 223, Fig. 2b, trained around sprockets 225, 226 on shafts 228, the bags being held on the chain by upwardly opening U-shaped clips 229. A Geneva mechanism coupled to the shaft 228 and driven by the shaft 157 is timed to advance the chain intermittently through steps equal in length to the spacing between the clips 229. A suction cup, Figs. 23, 24 (not shown), carried on an arm pivotable for back and forth oscillation is coupled to a vacuum source and grips and holds the leading bag 11 which, when severed from the tube 20, is swung downwardly through an arc so that the bottom of the bag is inserted into a clip 229, the source of vacuum then being disconnected to release the bag and the cup swung upwardly to receive the next bag. Upon transferrence to the conveyer the bags are advanced edgewise to the filling station 25 to receive a charge of bulky particles, the side panels of a bag being gripped by suction cups movable away from one another to pull apart the panels, a nozzle being lowered into the bag and around which the panels are clamped, the cups then being disconnected from the vacuum source, and a shot of pressurized air being injected into the bag to expand the side panels thereof; the clamping bars and nozzle are retracted to free the bag for advancement with the conveyer. The cups and nozzle are operated by cams 256, 257 and 263, respectively, on the shaft 157. Preparatory to filling each bag the upper end thereof is opened widely and formed into a generally circular mouth, this operation being performed by suction cups, Figs. 29, 30 (not shown), arranged in pairs on opposite sides of the bag. A charge of particles is deposited into the bag through a spout 279 which is fed from a known form of dispensing mechanism 280 driven by the shaft 156. Prior to forming the top seal 17 of the bag, the circular mouth of the filled bag is stretched and flattened by two fingers 283, which engage the inside of the bag and are moved away from each other along a line extending parallel to the bottom seal 18, after which shoes are swung together to crimp and interlock the side panels of the bag. The bags, with flattened and crimped mouths, are advanced between a pair of heated sealing bars 324 which iron out the crimped lines formed by the shoes and activate the adhesive strips 40 and to form the top seals 17. Finally the bags are advanced to the end of the conveyer 223, removed from the clips 229 and arranged in stacks for delivery to a cartoning machine. In modifications, the machine is adapted to form (a) tetrahedral bags, Figs. 35 to 40 (not shown), the top seal 17 extending transversely to the bottom seal 18, and the seam 16 being offset from the centre of the bag, (b) bags with V- shaped side gussets, Fig. 44 (not shown), (c) bags having a double longitudinal seam, Fig. 46 (not shown), formed by folding over upstanding faceto-face edge portions of the web 10, and (d) bags having bottom gussets, Fig. 48 (not shown), and finned side seal