| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent short circuit due to mutual contact of heating wires at the time of fusion, by forming the cross section of the heating wire at least on an end side where kink easily occurs into a shape that is easily bent in a diametral direction perpendicular to the pipe shaft of a plastic pipe to be fused. SOLUTION: For example, in an electric fusion socket joint 1, the cross section of a heating wire 2 is formed into an elliptical shape, and a short diameter having a small geometrical moment of inertia is directed to a diametral direction perpendicular to the pipe shaft of a plastic pipe to be inserted in. The shape of the heating wire 2, may use a short cross section or a tape shape instead of an elliptical cross section. In a joint using this heating wire 2, in the case that a kink occurs at the time of fusion, a kink 7 occurs in a diametral direction and hardly occurs in a pipe shaft direction, therefore short circuit due to the mutual contact of the heating wires 2 can be prevented. The whole of the heating wires 2 may be formed into a cross sectional shape or only a desired part, namely, only the heating wire 2 on an end side where the kink easily occurs may be formed into the cross sectional shape.</p> |
