| 摘要 |
PURPOSE:To obtain an iron core characterized in excellent magnetic characteristics, by winding a coil around the iron core, exciting the coil with a high frequency of 1kHz or more, and equalizing the values of temperature increases at various parts. CONSTITUTION:A coil 4 is wound around an iron core 3. The iron core 3 is placed in a metal case 2, which is provided in a vacuum annealing furnace 1. A high frequency of 1kHz or more is applied to the coil 4 from a high frequency power source 5, and an alternating magnetic field is generated in the coil 4. The temperature of the annealing furnace 1 is kept at an annealing temperature, and the annealing is performed. The temperature of the case 2 at this time is kept at the same temperature of the iron core 3. After the annealing, the vacuum state in the annealing furnace 1 is gradually released. By utilizing atmosphere, the temperature is lowered, and the iron core 3 is cooled. Thus the iron core 3 characterized by excellent magnetic characteristics is obtained.
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