| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent the short circuit of heating wires by providing a bend part at an appropriate part of the heating wire to be embedded in a coil shape outwardly in the radial direction to absorb and mitigate the buckling stress of the heating wire during electro-fusion. SOLUTION: The buckling stress generated in a heating wire during electro- fusion can be absorbed by forming a bend part which is bent outwardly in the radial direction on a second heating wire from an end part of a joint. A cavity part 6 of the prescribed length along a heating wire 5 is provided in a sealed manner outside the heating wire of the second coil from the end part of the joint for a slip-on electro-fusion joint 4 for plastic pipe so that the heating wire 5 is bent into a cavity part 6 when the heating wire 5 is buckled and bent during electro-fusion. A hole reaching an outer circumferential surface of a joint is formed diagonally outside the heating wire 5 so as to make the molten resin difficult to leak outside the joint, and bend of the heating wire 5 during fusion is absorbed by the hole.</p> |
