Induction heating furnace and bottom tapping mechanism thereof

An induction heating furnace comprising:

• an accommodating vessel having a bottom, a top edge portion, a tapping portion formed at said bottom, and a side wall extending so obliquely as to increase in radius from said bottom to said top edge portion and formed by a plurality of longitudinally split, conductive segments arrayed circumferentially and insulated from each other;
• a coil arranged at an outer periphery of said tapping portion and said side wall for subjecting a material accommodated in said accommodating vessel to induction heating;
• a power source supplying AC power to said coil;
• and
• a power source controller for controlling an amount of power produced by said power source such that said tapping portion is switched between open and closed states by melting and solidification of the material, wherein said coil is separated into a first coil portion arranged at an outer periphery of said side wall and a second coil portion arranged at an outer periphery of said tapping portion;
• said power source comprises a first power source supplying power to said first coil portion and a second power source supplying power to said second coil portion;
• said second power source comprises a solidification-use power source portion for producing a low-frequency power having a value selected for inducing eddy currents at a deep layer from the surface of the molten material so as to close the tapping portion by solidification of the molten material, and a melt-use power source portion for producing a high-frequency power having a value selected for inducing eddy currents at a thin layer from the surface of the molten material so as to open the tapping portion by melting of the molten material.