| 摘要 |
1,187,896. Seaming non-metallic sheet material. PAPER CONVERTING MACHINE CO. Inc. 19 April, 1968 [8 May, 1967], No. 18578/68. Heading B5K. [Also in Division H5] Apparatus for heat sealing superposed thermoplastic layers 10, e.g. polyethylene, comprises an electrically continuously-heated ribbon 19 and means for bringing a surface of heat-conductive cooling means 20 into contact with the ribbon 19 after the ribbon has effected a seal to cool the ribbon and prevent severing of the layers 10. A sealing element 14 and a backing element 15 are mounted on a frame (not shown), either element being movable towards and away from the other element. The element 15 comprises a roll rotatably mounted on a shaft 17 and provided with a resilient surface layer 18, e.g. of rubber. The element 14 comprises the continuously-heated metal ribbon 19 supported on a tubular member 20 filled with cooling fluid 21. Layers 23, 24 of thermal and electrical insulating tape, e.g. polytetrafluoroethylene, are provided on each side of the ribbon 19. A current supply lead 25 is clipped at 26 to the ribbon 19 which is arched slightly in the transverse direction. Normally a space 27 is formed between the ribbon 19 and the cooled tube 20 but, in use, the ribbon is pressed against the tube. To provide a continuous rather than an intermittent sealing operation, the elements 14, 15 are mounted on moving chains to heat seal a moving web. The apparatus may be used to transversely seal a flattened tubular web having side gussets to form a roll of end-connected bags which can be detached by lines of weakness or perforations situated adjacent to the seals. |
