| 摘要 |
<p>PURPOSE: To stop heating at the time of the appearance of the optimum welding condition without generating a connection flaw by using a resistance foil embedded in an electrically weldable joint to have welding function at welding temp. CONSTITUTION: An electrically weldable joint is connected by fitting two pipes 6, 8 in the central opening 4 of a connection sleeve 2 made of heat-fusing plastic. The pipes 6, 8 extend over a length L along the opposed surfaces 6a, 8a of the sleeve 2 and an electric heating resistor 10 connected to an electric energy source by two connection terminals 12, 14 is provided and constituted of a foil 11 made of a conductive material. The foil 11 is formed on a support film 13 of heat-fusing plastic by vacuum vapor deposition welding. When the support film 13 reaches the softening temp. of the material constituting the support film and succeedingly reaches the welding temp. thereof, it expands to generate a crack in a conductive layer 11 at first and the continuous cleavage passing the whole thickness of this layer 11 is generated and a current is cut off and heating is interrupted.</p> |
