| 摘要 |
773,033. Pipe joints. SOC. PER AZIONI LA RESINA. Sept. 14, 1955 [Sept. 25, 1954], No. 26260/55. Class 99(1) In a spigot-and-socket joint having a pipe 1, Fig. 1, of thermoplastic material with a a socket provided at one end-by deformation at an elevated temperature, and a second pipe 3 having a resilient gasket ring 6 around the end which is inserted into the socket, the latter, due to the property of thermoplastic materials to resume their original shape whenever they are heated a second time after deformation at an elevated temperature, is contracted into the pipe 3 and the gasket 6 upon reheating the socket. The pipe 1 of such material, as PVC, has the socket formed by the insertion of a mandrel after softening the pipe end by heat; the pipe 3 is of metal or plastic whilst the gasket 6. is made of rubber. Upon reheating the socket it shrinks on to the pipe 3 as shown in Fig. 2 and presses the gasket 6 radially; the shrinking action may be assisted by applying a, metal sleeve around the bell mouth. Such a joint permits relative axial movement between the pipes without leakage occurring. In a modification, the pipe 1 has a single bell mouth and the pipe 2 is formed with a bulge behind the gasket. In another modification, the pipe 2 is provided with a bell mouth and two spaced gaskets; the pipe 2 may have a number of protrusions of any suitable shape. |
