| 摘要 |
PURPOSE:To prevent the deterioration of the magnetic characteristic of an iron core formed by winding thin foil of an amorphous alloy due to the generation of the thermal stress by mounting a heat insulating material to the inside and outside peripheral faces of the iron core to minimize the temp. difference in the iron core during cooling at the time of annealing the above-mentioned iron core for the purpose of stress relieving. CONSTITUTION:The melt of a magnetic alloy is ultrarapidly cooled at 10<6> deg.C/sec cooling rat to form the amorphous thin foil and the annular magnetic iron core 1 is formed by winding such foil. Since the iron core is susceptible to the deterioration of the magnetic characteristics by the effect of work strain, the iron core is heated to about 350 deg.C and is thereby annealed in an inert gas. The cooling rate after the annealing is considerably different between the axial direction and the radial direction within the iron core in this case, by which thermal stress is generated to deteriorate the magnetic characteristic. Sheets 2, 2 made of the heat insulating material such as glass wool are mounted to the inside and outside peripheral faces of the annular iron core 1 and an excitation coil is wound on the outside in order to prevent such deterioration. The iron core is then cooled after the annealing in the magnetic field, by which the thermal stress generated in the iron core is small; therefore, the deterioration of the magnetic characteristics by the generation of the thermal stress is prevented. |
