| 摘要 |
PURPOSE:To prevent the generation of the defect of a product by arranging an induction coil around a mold, providing the power source having two kinds of high and low frequencies as well, heating a molten metal by high frequency and agitating it by low frequency. CONSTITUTION:A metallic frame 7 of nonmagnetic metal is arranged surrounding a mold 1 and an induction coil 8 is provided on its circumference. The power source 10 of high frequency of >=50Hz and the power source 9 of low frequency of 1.5-20Hz are respectively arranged as the power source feeding an electric power to the coil 8. A switch 11 is switched to the power source 10, a molten metal is poured from a gate 3, the molten metal surface easy to over-cool is heated and the the switch 11 is switched to the power source 9 to give an agitation to the molten metal with the power of low frequency. Due to the temp. of the molten metal being uniformized at all times, it is thus prevented that the molten center part is solidified at last and the defect generation of a product is prevented.
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