| 摘要 |
1,138,132. Seaming non-metallic sheet material. ROHREN-KELLER A.G. 5 April, 1967 [15 April, 1966], No. 15522/67. Heading B5K. [Also in Division F2] In a method of welding together members made of thermoplastic material by first heating portions of the members to a welding temperature and then pressing these portions together, mould parts are applied to each side of the portions to prevent the thermoplastic material from spreading perpendicular to the direction in which the portions are pressed together and the portions are then pressed together with a pressure of from 10 to 100 kg. per sq. cm. The members may be butt welded or lap welded together and the portions may be heated by infra-red or other radiation, by contact with a heating element, by a flame or by induction heating. In one embodiment, Figs. 1 and 2 (both not shown), the edge portions of two sheets (1), (2) of hard polyvinyl chloride are heated to welding temperature and are abutted in a mould comprising a U-shaped trough (3) having a lid (4) secured thereto by locks (5) or clamps. The sheets are pressed together by a force (F) which at the weld produces a pressure of 10-50 kg. per sq. cm. if the mould has been preheated to a temperature which is at least halfway between room temperature and the welding temperature and at most 10‹ C. below the welding temperature and a pressure of 20-100 kg. per sq. cm. if the weld has not been preheated. In a further embodiment, Fig. 3, the end portions 6a, 7a of two polyethylene tubes 6, 7 are heated to a welding temperature and then abutted in a mould formed by metal cylinders 8, 9. A force F is applied either by means of pressure plates 10 or rings 11 and produces a pressure at the weld in the ranges specified above. In another embodiment, Fig. 5, a polypropylene tube 13 is welded into the wall of a tube 12, an opening being simultaneously or subsequently cut in the tube 12 through the tube 13. Preheated cylinders 14, 15, 16 form the mould and a force F is applied to a pressure ring 18. In a still further embodiment, Fig. 6 (not shown), portions (19a), (20a) of hard polyethylene sheets (19), (20) are heated to the welding temperature and overlapped. Metal bars (21), (22) serve as mould parts and the welding force is exerted on pressure plates (23), (24). |
