| 摘要 |
984,797. Seaming non-metallic sheet material. D. F. BATE, and LERNER MACHINE CO. Ltd. Sept. 21, 1962 [Sept. 21, 1961], No. 33928/61. Heading B5K. [Also in Division B8] At least two layers of thermoplastic sheet material are sealed together by directing a supply of hot gas against an outer exposed surface of one of said layers in the region to be sealed, controlling the temperature and duration of the gas supply and subsequently directing a supply of comparatively cold gas against said outer exposed surface to cool the seal. An article wrapped in thermoplastic material, e.g. polyethylene, is placed on a base 3 between walls 1, 2 in the apparatus shown. Hot gas, such as air, is directed through conduits 6 and 11 into grooves 5 and 10 respectively shaped to correspond to the desired seal areas on the ends and base of the wrapped article. After the softening and melting of the thermoplastic material cold gas to cool the seal is supplied through conduits 6, 11. The walls 1, 2 are spaced apart to ensure that the article is a snug fit therebetween. One wall may be movable and provided with biasing means to apply pressure to the end faces of the article. A plurality of grooves may be provided in each wall. The apparatus may form part of a wrapping machine and have the wrapped articles conveyed intermittently thereto. The apparatus may be used to make an overlap joint or a butt joint between two layers of material. |
