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Powder mixture for dust cores

A powder magnetic core and mixed powder technology, which is applied in the direction of magnetic core/yoke, inductor/transformer/magnet manufacturing, magnetic materials, etc., can solve the problems of molded body expansion, magnetic property reduction, inductance reduction, etc., and achieve suppression of expansion , The effect of preventing density reduction and suppressing deterioration

Active Publication Date: 2013-07-31
KOBE STEEL LTD
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Problems solved by technology

[0011] However, if the mixed powder mixed with a lubricant in the soft magnetic iron-based powder is molded, and the obtained molded body is subjected to heat treatment, the size of the molded body changes before and after the heat treatment, and the molded body expands due to the heat treatment.
In addition, molded products that expand due to heat treatment tend to have lower magnetic properties.
Especially when the molded body is an inductor with an outer iron shape, there are problems such as a drop in inductance due to expansion.

Method used

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  • Powder mixture for dust cores
  • Powder mixture for dust cores

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Embodiment Construction

[0018] The present inventors, when heat-treating a molded body obtained by molding a mixed powder of soft magnetic iron-based powder and a lubricant coated with an insulating film, in order to suppress the expansion of the molded body, the dimensions of the molded body before and after the heat treatment were adjusted to The rate of change is less than 0.001% and has been studied repeatedly. As a result, they found that the rate of dimensional change of molded articles due to heat treatment can be reduced by appropriately adjusting the particle size distribution of the mixed powder, and completed the present invention. Hereinafter, the reason for accomplishing the present invention will be described.

[0019] Among the dust cores, for example, powder cores used for inductors, when the excitation frequency is high frequency, in order to reduce eddy current loss, soft cores with a small particle size (for example, particle size of 150 μm or less) are generally used. Magnetic ir...

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Abstract

The invention provides a powder mixture for dust core, which contains an insulated skin and lubrican on the surface of soft magnetic iron-based powder. When applying a heat process for a shaping body obtained by the powder mixture, a demensional change of the shaping body before and after the heat process is reduced, especially expansion caused by the heat process is inhibited. The powder mixutre whose grain size is below 106 mu m is more than 95% of the total powder mixture by mass, and the powder mixutre whose grain size is below 45 mu m is less than 40% of the total powder mixture by mass (40% is excluded).

Description

technical field [0001] The present invention relates to soft magnetic iron-based powders used in the manufacture of powder magnetic cores for electromagnetic components such as inductors. Background technique [0002] Electromagnetic elements such as inductors are often used in an AC magnetic field, and magnetic cores (core materials) are used in these electromagnetic elements. The magnetic core has conventionally been manufactured by processing laminated electrical steel sheets. However, magnetic cores obtained by processing electromagnetic steel sheets have directional magnetic properties, so it is difficult to design electromagnetic elements with three-dimensional magnetic circuits. Therefore, in recent years, techniques for manufacturing dust cores by press-molding soft magnetic iron-based powders have been studied. Since the magnetic properties of the dust core are isotropic, it is possible to design an electromagnetic element with a three-dimensional magnetic circuit...

Claims

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Application Information

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IPC IPC(8): H01F1/147H01F1/24H01F41/02
CPCH01F1/24H01F41/0246H01F27/255H01F3/08
Inventor 三谷宏幸北条启文上条友纲
Owner KOBE STEEL LTD
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