| 摘要 |
<p>PROBLEM TO BE SOLVED: To make the electromotive power inside a loop circuit zero and prevent earth current generation by arranging a plurality of C-type inductors in parallel in the transportation direction of an object to be heated and setting the magnetic flux direction of neighboring inductances mutually inverse directions. SOLUTION: When both ends of a billet 6 are locally heated, high frequency electric current is applied to heating coils 3 of C-type inductors 8A, 8B. At this point, the inductors 8A, 8B are so composed as to generate the magnetic fluxes by the inductors 8A, 8B in mutually inverse directions. Consequently, the electromotive force due to the generated magnetic fluxes are mutually canceled and becomes zero and thus an earth current does not flow. As a result, even if the billet 6 is brought into contact with a transportation roller 5, no earth current flows and no spark is generated and thus spark scratch formation can be prevented. Moreover, an insulating countermeasure for a large number of rollers 5 is made unnecessary and installation cost can be lowered.</p> |
