| 摘要 |
821,863. Joining plastic pipes &c. CRANE PACKING Ltd. Oct. 3, 1957 [Oct. 19, 1956], No. 31894/56. Class 99(1). In a method of welding synthetic plastic materials for the purpose of inseparably connecting two elements of such material when one element embraces the other, as in the plugging or jointing of plastic pipes, restraining means are applied around one element which embraces the other and the temperature of the restrained assembly is raised above the transition point of the material if both elements are of the same material, or the lower transition point in the case of different materials, so as to utilise the expansion of the restrained assembly to weld the two elements together. As shown in Fig. 1, a rod 2 of polytetrafluoroethylene slidably fits wtihin a pipe 1 of the same material, the pipe being bound with an openly or closely wound wire coil 3. The assembly is allowed to cool after heating in an oven to a temperature of about 360‹C. to result in a plugged end of the pipe. Alternatively, the plugged pipe end is obtained by the use of electrically-heated clamping plates. Pipe ends are joined by inserting in the aligned bores of the pipes 9, 10 a tubular liner 11, Fig. 4, of glass or metal, and a metal sleeve 13, or coil of wire is fitted over a sleeve 12 of polytetrafluoroethylene, the assembly being heated to about 360‹C. and allowed to cool, and the sleeve and liner then being removed ; glass liners are shattered and the broken pieces blown from the pipes by compressed air, and metal liners are removed by the use of a corrosive medium or pushed out from short pipes by a rod. Alternatively, the pipes are joined by clamping the ends of the-pipes in recessed jaws carried by relatively movable blocks incorporating electric resistance heating elements.
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