| 摘要 |
958,552. Seaming non-metallic sheet material. HAMAC-HANSELLA A.G. July 9, 1962 [Oct. 11, 1961], No. 26236/62. Heading B5K. A device for producing a longitudinal welded seam 6 on a thermoplastic tube 4 comprises a heatable welding member 2 to press the material to be welded against a backing member 3 whilst a heat-resisting layer 1 is interposed between the member 2 and the tube 4, the layer 1 consisting of a flexible strip secured at its opposite ends to the respective ends of the member 2 but is otherwise free to move with respect to the member 2 so that after the seam 6 has been welded by the member 2 the latter can be withdrawn, leaving the layer 1 temporarily in contact with the seam 6 during cooling thereof. The tube 4 is formed around a former 3 and is moved intermittently downwards. The layer 1 is preferably made of polytetrafluoroethylene and is attached at its upper and lower ends to the member 2. After cooling of the welded seam 6 the tube 4 is pulled downwardly and the layer 1 peels off. The member 2 may be heated continuously or intermittently by electrical resistance and may be thermostatically controlled. A blower to assist cooling of the seam 6 may also be provided.
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