Patent GB-1494542-A (GB)
Title: Cutting and sealing a thermoplastic film web to produce bags
IPC: B29C65/74
Filed: 1975-02-10
Abstract: 1494542 Seaming non-metallic sheet material; making bags FMC EUROPE NV 10 Feb 1975 [20 Feb 1974] 5501/75 Headings B5K and B5D Apparatus 1 for cutting and sealing at least one thermoplastic film web to produce bags comprises a reciprocable cutting and sealing bar 15, a lower stationary assembly having two holding and coolings bars 17A, 17B adjustably mounted on a beam 18 extending transvesely to the web feed direction, an upper movable assembly having a support beam 13 carrying the bar 15 and resiliently carrying two holding and cooling bats 16A, 16B arranged symmetrically with respect to the bar 15, a coolant circuit for the bars 16A, 16B, 17A, 17B, and means for detaching the film from the bars 16A, 16B, 17A, 17B after operation of the bar 15. In the apparatus described, two longitudinally folded thermoplastic film webs (5), (6), Fig. 1 (not shown), are fed simultaneously by rollers (2A), (2B) to the apparatus 1 which transversely cuts and seals the webs to form individual bags which are removed by belts 3B, Fig. 3. The lower bars 17A, 17B, Figs. 2 and 3, separated by spacers 23 are mounted on a plate 19 secured to the beam 18 so as to be adjustable w.th respect to planes XX 1  and YY 1 . Cold water or refrigerant fluid is circulated through passages 24 in the bars 17A, 17B through inlet, outlet and connecting hoses 24A, 24B, 25, respectively. Nozzles 28 in the bar 17B are supplied w.th compressed air through tubes 27 connected by hoses 29 to two splitter boxes 30, 31 corresponding to the webs (5), (6), respectively. The boxes 30, 31 are supplied by a main hose 32 through a two-way control valve 33 and are provided with control valves so that, for example, the whole or only part of the nozzles 28 may be supplied continuously or intermittently.  The bar 15 is heated by an electrical resistance 15B and is suspended from the vertically movable beam 13 by members 36. The beam 13 is provided with a locking bolt 14 to enable the upper assembly to be locked in its active position with the bolt 14 in an opening 39 in a member 41 or in an inactive position in which the bar 15 has no action of the film while the beam 13 continues to be raised and lowered, the bolt 14 being in an opening 40. Four lower bars 16A, 16B, 16C, two for each film web, are provided and are suspended from the beam 13 by adjustable supports 42 having guide rods 43 along which the bars 16A, 16B, 16C can be displaced upwardly against the action of springs 44. The bars 16A, 16B, 16C are provided with passages 45 and connecting hoses 46, 47 for the circulation of a refrigerant therethrough. The bars 16B, 16C have nozzles 28A supplied with compressed air by a system identical to that of the bar 17B. In operation, after a film feed step, the upper assembly is lowered and the bars 16A, 16B, 16C clamp the wdbs against the bars 17A, 17B. Continued lowering of the beam 13 causes the bar 15 to descend against the action of the springs 44 until it contacts the webs to effect sealing and cutting thereof. The dwell time of the bar 15 in this position is determined by the shape of a cam controlling the movement of the beam 13. When the beam 13 rises, the bar 15 and, subsequently, the bars 16A, 16B, 16C disengage the webs. Compressed air from the nozzles 28, 28A facilitates detachment of the film from the holding bars and assists forward feed thereof.