JPH0590051A - Production of magnetic core - Google Patents

Abstract

PURPOSE:To stress generated at the time of forming a gap and improve core loss characteristic by re-heating a magnetic core for relaxing the stress generated at the time of cutting after being cut. CONSTITUTION:A toroidal magnetic core body 12 manufactured by take-up device is heat-treated in an electric furnace, is impregnated with epoxy resin and heat-cured. Then, one part on a magnetic path is cut by a rotating cutting blade and a gap is formed. A spacer 14 composed of a glass epoxy resin plate is inserted into the gap 13 and the spacer 14 is adhered to the cut plane of the magnetic core body 12 by adhesive. The magnetic core body 12 mounted with the spacer 14 is heated in an electric furnace. Thus, a stable characteristic with less core loss is attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic core obtained by winding a magnetic ribbon, and more particularly to a technique effectively applied to alleviate stress generated during gap formation.

[0002]

2. Description of the Related Art A magnetic core used in this type of choke coil or a high frequency transformer is required to have a constant magnetic permeability, that is, its magnetic permeability is substantially constant without depending on the magnitude of the magnetic field H.

In order to satisfy this constant permeability, in a so-called amorphous core made of an amorphous alloy, first, a thin strip of an iron-based amorphous alloy is wound a predetermined number of times,
After heat-treating this, impregnate it with an adhesive such as epoxy resin,
Solidify, then cut part of the magnetic path, gap
Was provided and a spacer was inserted into this gap as needed to realize the above-mentioned constant permeability.

[0004]

However, when the gap is provided, the magnetic cutting path is cut at one or two places by the rotary cutting blade. However, when the stress of the cutting blade is applied to the cut surface of the magnetic path. It has been found by the present inventor that the iron loss characteristic of the magnetic core is reduced by 10% or more due to the residual, the variation occurs depending on the product, and the stable characteristic cannot be obtained.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a magnetic core having a stable characteristic that relieves the stress generated when the magnetic path is cut.

[0006]

That is, according to the present invention, a magnetic ribbon of a winding body obtained by winding a magnetic ribbon in a predetermined shape, heat-treating the magnetic ribbon, and then impregnating and hardening the curable resin is provided. In the method of manufacturing a magnetic core for cutting a portion, reheating is performed after the cutting, which is a method of manufacturing a magnetic core.

In the present invention, the amorphous magnetic alloy ribbon means a ribbon obtained by processing an amorphous magnetic alloy.
As the amorphous magnetic alloy, for example, a Fe-based amorphous alloy (Fe-based amorphous alloy having a Fe content of 50 atomic% or more) can be used. As, Fe-B, Fe-BC, Fe-BS
i, Fe-B-Si-C, Fe-B-Si-Cr, Fe
-Co-B-Si, Fe-Ni-Mo-B etc. can be illustrated.

Among these, Fe _X Si _Y B _Z M _W can be exemplified as a particularly preferable Fe-based amorphous alloy. Where X =
50-85, Y = 1-15, Z = 5-25 (X, Y, Z
Both represent atomic%). Also, M is C
o, Ni, Nb, Ta, Mo, W, Zr, Cu, Cr,
Metals composed of one kind or a combination of two or more kinds of Mn, C, Al, P and the like, and W = 0 to 5 atomic% can be exemplified.

According to the present invention, such an amorphous alloy ribbon is wound to obtain a magnetic core main body, the magnetic core main body is subjected to a first heat treatment, and then the magnetic core main body is impregnated with an epoxy resin and cured. After that, a part of the magnetic path of the magnetic core body is cut with a rotary cutting blade. At this time, the number of cutting points may be one, but from the viewpoint of stress relaxation during cutting, a plurality of points may be cut.

After that, a spacer or the like may be inserted into the gap formed by cutting the magnetic path for the purpose of keeping the gap constant. Next, the second with respect to the magnetic core body
Heat treatment (reheating) is performed. This reheating significantly relaxes the stress in the magnetic core body.

[0011]

In this way, the internal stress can be relaxed by reheating on the basis of the following principle. That is, the impregnated resin that has been hardened by reheating softens, plastic deformation becomes easier, and viscous flow of the resin occurs in the direction that alleviates the partial residual processing strain that remains due to cutting, spacer insertion, etc., and strain stress is significantly increased. It can be reduced.

The reheating temperature range is 70 ° C. to 20 ° C.
0 ° C is preferred. If the temperature is below this temperature range, relaxation of the internal stress cannot be expected, and if it is above this temperature range, the impregnated resin may be thermally deteriorated. The temperature range is more preferably 70 ° C to 150 ° C.

The reheating time is 10 minutes to
About 2 hours is preferable. As the reheating treatment atmosphere,
It may be in the air or in an inert atmosphere such as nitrogen gas.

As described above, according to the present invention, the second heat treatment (reheating) after cutting the magnetic path relieves the stress remaining in the main body of the magnetic core, so that the iron loss is reduced and the stability is improved. The product characteristics can be obtained.

[0015]

[Example] Amorphous Ribbon (Product name:
Metglas, product number: 2605S-2, composition: Fe ₇₈
B ₁₃ Si ₉ (atomic%), thickness 21 μm, width 10 mm) was wound using the winding device shown in FIG.

In FIG. 1, a roll 3 for supplying the ribbon 1 is provided, and the ribbon fed from the roll 3 passes through the tension detecting roll 4, the cutter 5 and the ribbon feeding device 9 and is fed to the winding core 6. It has a structure to supply.

Outer diameter 2 obtained by the winding device
The toroidal magnetic core body 12 having a diameter of 5 mm and an inner diameter of 15 mm was annealed for 2 hours (first heat treatment) in an electric furnace. next,
After the magnetic core body 12 was impregnated with epoxy resin and cured by heat, one portion of the magnetic path was cut by a rotary cutting blade 16 to form a gap, as shown in FIG.

Next, as shown in FIG.
A spacer 14 made of a glass epoxy resin plate was inserted into the above, and the spacer 14 and the cut surface of the magnetic core body 12 were bonded with an adhesive.

The magnetic core body 12 thus equipped with the spacer 14 was heated in an electric furnace under the conditions shown in Table 1. The magnetic core body 12 thus obtained was housed in a container to obtain a magnetic core.

The iron loss characteristics of this magnetic core are shown in Table 1 below.
At this time, the iron loss was measured by using a U function meter to excite the magnetic flux sine wave of 100 kHz to 0.1T.

[0021]

[Table 1]

[0022]

[Comparative Example] Amorphous ribbon manufactured by Allied Company (Product name: Metglas, Product number: 2605S-
2, composition: Fe ₇₈ B ₁₃ Si ₉ (atomic%), thickness 21μ
m, width 10 mm) was wound using the winding device shown in FIG. 1 to obtain a magnetic core main body 12 similar to that of the above-mentioned embodiment, and then annealed under the same conditions as in the embodiment, impregnated with resin, and the gap 1
3 was provided, the spacer 14 was mounted in the gap 13, and then the magnetic core was obtained by accommodating the spacer 14 in the container without performing the reheating treatment.

Table 1 shows the iron loss characteristics of the magnetic core in this comparative example.
Shown in. As shown in Table 1, it is clear from the difference in iron loss characteristics between the example and the comparative example that the reheated example can significantly reduce the iron loss.

[0024]

According to the present invention, it is possible to realize stable characteristics with less iron loss in a magnetic core in which a gap is formed by cutting a part of the magnetic path.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a winding step for obtaining a magnetic core body of the present invention.

FIG. 2 is an explanatory view showing a step of cutting a magnetic path in a manufacturing process of a magnetic core.

FIG. 3 is an explanatory view showing a step of inserting a spacer into the gap in the manufacturing process of the magnetic core.

[Explanation of symbols]

 1 ... Ribbon 3 ... Roll 4 ... Tension detection roll 5 ... Cutter 6 ... Core 9 ... Ribbon feeding device 11 ... Ribbon thickness measuring device 12 ... Magnetic core body 13 ... Gap 14 ... Spacer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location H01F 41/02 C 8019-5E

Claims (3)

[Claims] 1. A process for producing a magnetic core, which comprises winding a magnetic ribbon into a predetermined shape, heat-treating the magnetic ribbon, impregnating a curable resin and curing the curable resin to cut a part of a magnetic path of the wound body. A method for manufacturing a magnetic core, which comprises reheating after the cutting. 2. The method of manufacturing a magnetic core according to claim 1, wherein the reheating is performed in a range of 70 ° C. to 150 ° C. 3. The method of manufacturing a magnetic core according to claim 1, wherein a spacer is inserted into a portion of the wound body where a magnetic path is cut.