JPS6047401A - Magnetic core - Google Patents

Abstract

PURPOSE:To obtain a magnetic core for high frequencies able to prevent short- circuit between layers during the cutting operation and to reduce the external stress during the fixing operation, by winding an amorphous magnetic thin strip such that an adhesive agent is impregnated only between the layers to leave both the inner and outer surfaces of the thin strip uncovered. CONSTITUTION:An amorphous magnetic thin body 1 is wound to shape a torus and subject to heat treatment at as high temperature as possible but lower than the crystallization temperature of amorphous substances in order to separate the fine crystalline phase. Subsequently, an epoxy resin 2 as an adhesive agent is impregnated into the core, while the inner and outer sides of the core are covered with clay so that no resin is laid thereon. After the resin cures, the core is cut off diametrically with a magnet blade. Thereby, the short-circuit between the layers during the cutting operation can be prevented, and the external stress can be reduced by inhibiting the magnetic walls from permanent fixation during the fixing operation. Thus, the core loss at higher frequencies can be reduced effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a magnetic core made of amorphous magnetic ribbon used for high frequency coils, transformers, etc.

[Background technology]

A magnetic core made of amorphous magnetic ribbon is mainly manufactured by winding the ribbon in a spiral shape using a single roll method or a double roll method, but the thickness of the ribbon is at most 250 mm for Fe-8i-B series.
μm, and cannot be put to practical use unless laminated. Moreover, if only lamination is used, problems will arise in terms of strength, etc., so the one-turn iron core must be fixed.

Furthermore, when used in a high-frequency transformer, the magnetic core must be cut to insert a coil or to meet the needs of a magnetic circuit. When cutting with a wire saw or a whetstone blade, chips from the magnetic core entered the glabella or sag formed in the magnetic ribbon, causing interlayer short circuits and deteriorating magnetic properties. Furthermore, when fixing the entire one-turn core, adhesive resin is used to bond the layers at the same time, or the curing of this resin applies shrinkage stress to the magnetic core, which causes the domain wall to become fixed and prevent the domain wall from moving smoothly. Iron loss increased at high frequencies.

[Purpose of the invention]

An object of the present invention is to provide a magnetic core that does not cause interlayer short circuits when cut, has less external stress when the whole is fixed, and has less core loss at high frequencies.

[Disclosure of the invention]

The magnetic core of the present invention is an amorphous magnetic ribbon that is wound with an adhesive impregnated only between the layers, with the ribbon fabric exposed on both the inner and outer surfaces without adhesive.

Example 1 An amorphous ribbon with a composition of Fe9g Si5 B□6 and a thickness of 25 μm was prepared with an inner diameter of 20 mm and an outer diameter of 35 μm.
It was wound in the shape of a horseman's ring. This was heat treated at 450°C for 45 minutes. Amorphous magnetic ribbons are made by ultra-rapidly cooling molten metal, and their magnetic properties deteriorate due to the large internal stress caused by the molten metal. Therefore, removing internal stress,
In order to further improve magnetic properties and obtain a magnetic core with low iron loss,
It is preferable to precipitate a fine crystal phase within the amorphous, and it is necessary to perform the heat treatment at a temperature as high as possible below the crystallization temperature.

After the heat treatment, it is impregnated with an epoxy resin (Rubeasoku, manufactured by Gyudon Kagaku Co., Ltd.), which is an example of an adhesive.

It was left at 80'C for 2 hours. At that time, inside the magnetic core.

I covered the outside with adhesive to prevent resin from getting on it. After the resin had hardened, it was cut in the diametrical direction using a grindstone blade. The cut surface at that time is shown in FIG. 1σ amorphous magnetic ribbon, 2-layer resin (adhesive). The figure shows that no short circuit occurs between the eyebrows. It should be noted that before cutting, when a frequency is applied, insulation between layers is sufficiently maintained just by winding.

As Comparative Example 1, FIG. 2 shows a cut piece without impregnating the glabella with resin. It can be seen that a short circuit between layers has occurred. That is, as shown by 3 at the cut surface, the ribbons j are sagging and are in contact with each other, and the chips 4 have penetrated between the layers.

Comparative Example 2 A heat treatment was performed in the same manner as in Example 1, and the interlayers and the outside and inside of the magnetic core were fixed with resin. 2 in Table 1
The iron loss value at 0KHz and 3K Gauss is shown.

When the magnetostriction constant is large, the domain walls become fixed due to stress, but not applying adhesive on the outside or inside of the magnetic core is
This is to reduce the influence of stress caused by curing shrinkage and to suppress fixation of domain walls.

Example 2 An amorphous magnetic ribbon having a composition of Fe76 CrI 5113 Bl ( ) with a thickness of 0 mm + 28 μm was wound in an annular shape between an inner diameter of 20 am and an outer diameter of 30 mm.
Heat treatment was performed at 0°C for 50 minutes. Thereafter, the same fixation as in Example 1 was performed.

For comparison, the same fixing as Comparative Example 2 was performed (Comparative Example 3)
. Both were cut with a grindstone blade and the iron loss value was measured at 20 KHz and 3 K Gauss. The results are shown in Table 2.

In addition, Example 11d' magnetostriction constant 30X]0, Example 2
It was large at 20x10.

〔Effect of the invention〕

According to the magnetic core of the present invention, no interlayer short circuit occurs when cutting, there is less external stress when the whole is fixed, and the core loss value at high frequencies is reduced in both cases.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an example of the present invention, and FIG. 2 is a schematic cross-sectional view of Comparative Example 1.

Claims (1)

[Claims] A magnetic core made by winding an amorphous magnetic ribbon with adhesive impregnated only between the layers and with the ribbon fabric exposed on both the inner and outer surfaces.