| 摘要 |
PURPOSE:To make application to either of low-frequency power supply or high- frequency power supply for improvement of convenience by forming a wire rod which is formed near a connecting surface of a joint body with a conducting layer on the center line and a magnetic alloy layer formed at its surface. CONSTITUTION:This electric fusion joint 10 is provided with a roughly hollow cylindrical body 12 which is made of synthetic resin such as polyethylene, the hollow part of the body 12 serves as a socket 16 which receives a pipe 14 to be connected, and a wire rod 18 which is wound in a coil shape is embedded near the internal surface of the socket 16. The wire rod 18 is formed with a conducting layer 20 whose cross section is circular and which is made of a conducting body of copper-nickel alloy or the like and a magnetic alloy layer 22 which is formed at its surface and includes a magnetic alloy such as iron- nickel alloy. It is thus possible to heat the wire rod 18 by its combined resistance when low-frequency voltage is applied, and heat, the magnetic alloy layer 22 by concentrating electric current on the magnetic alloy layer 22 by a skin effect when high-frequency voltage is applied. |
