| 摘要 |
<p>PROBLEM TO BE SOLVED: To efficiently and uniformly execute the heat treatment to a cylindrical metallic coil in short time. SOLUTION: An annular transformer is constituted by connecting an iron core 2 penetrating the inside of a coil 1 which forms a cylinder state by winding a metallic strip so as to insulate between the strips, with an iron core 3 winding a primary coil 4 at the outside of the cylindrical metallic coil 1. Then, the metallic strip at the outermost peripheral part of the cylindrical metallic coil 1 and the metallic strip at the innermost peripheral part are short-circuited with a conductive member 5 to constitute a secondary closed circuit. The electric current is supplied in the cylindrical metallic coil 1 and heated by applying the voltage into the primary coil 4. The temp. is uniformized by arranging heat insulating layers 9, 10 on the outer surface and the inner surface of the heated cylindrical metallic coil 1. Further, the improvement of temp. distribution is obtd. by intermittently supplying the heating current.</p> |
