JPS6134914A - Manufacture of amorphous magnetic core - Google Patents

Abstract

PURPOSE:To alleviate the stress applied to a wound body when resin is hardened, to reduce the deterioration of magnetic characteristics, and to obtain the magnetic core of low iron loss having excellent magnetic characteristics by a method wherein a resin molding work is performed while tensile stress is applied to the wound body of amorphous magnetic thin strip. CONSTITUTION:A resin molding is performed while tensile stress is being applied to the wound body whereon an amorphous magnetic thin strip having magnetostriction is wound around. For example, an elastic body 1 such as rubber, having the outside diameter a little smaller than the inside diameter, is inserted in the inner side of the wound body 2 of amorphous thin strip, and when compression stress (a) is applied on both upper and lower faces of the elastic body 1, the diameter of the elastic body 1 is increased in the center part, and as a result, the thin strip is subjected to tensile stress (b). Accordingly, a magnetic core on which the deterioration of magnetic characteristics is reduced can be obtained by performing a resin molding under the above-mentioned condition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for manufacturing a toroidal core (ring-shaped magnetic core) in which an amorphous magnetic ribbon is wound and resin molded.

[Background technology]

Compared to ferrite, a soft magnetic material conventionally used, amorphous magnetic ribbon has a temperature higher than the Curie temperature (Tc).
, has a large saturation magnetic flux density (Bs), and has a large electrical resistance and high magnetic permeability compared to silicon steel sheets and permalloy, and is attracting attention as a new soft magnetic material.

By the way, cobalt-based amorphous magnetic ribbons have small magnetostriction and by adding appropriate additive elements, it is possible to produce a material with zero magnetostriction, but cobalt-based amorphous is expensive and has Bs, It had the disadvantage of low Tc. On the other hand, iron-based amorphous is
Compared to cobalt-based products, the cost is lower, and Bs,
Although both Tc was high, it had the drawback of large magnetostriction. For this reason, even if iron-based amorphous exhibits excellent magnetic properties immediately after heat treatment, it is known that the magnetic properties deteriorate when resin molding is performed to cut the magnetic core or wind the wire. .

[Purpose of the invention]

In view of the above, an object of the present invention is to provide a method for manufacturing a magnetic core in which magnetostrictive amorphous magnetic ribbon is wound and resin molded, in which deterioration of magnetic properties due to resin molding is reduced by m. .

[Disclosure of the invention]

In order to achieve the above object, the present invention is directed to a method of manufacturing a magnetic core in which an amorphous magnetic ribbon having magnetostriction is wound to form a wound body, and this is molded with resin, while applying tensile stress to the wound body. The gist is a method for manufacturing an amorphous magnetic core, which is characterized by molding. below,
This invention will be explained in detail.

By winding an amorphous magnetic ribbon to create a toroid-shaped magnetic core and applying appropriate heat treatment, it is possible to eliminate distortion and winding strain during amorphous manufacturing, and to precipitate a fine crystalline phase for high frequency applications. Excellent magnetic properties such as iron loss and high magnetic permeability can be obtained. However, in the case of iron-based amorphous, the magnetostriction is large, so when resin molded, the characteristics deteriorate. This is because, after the amorphous magnetic ribbon is molded with resin, the magnetic domain structure changes due to the reaction from the resin. The causes of this stress are those caused by contraction of the resin when it solidifies, and those caused by the process of cooling the resin to room temperature after solidification due to the difference in thermal expansion coefficient between the resin and the amorphous ribbon. etc. are possible. Generally, the thermal expansion coefficient of resin is larger than that of an amorphous ribbon, so the wound body after resin molding is subjected to compressive stress. Therefore, if tensile stress is applied to the wound body during resin molding, compressive stress generated after molding can be alleviated, and deterioration of magnetic properties can be reduced. There are several possible ways to apply tensile stress to an amorphous ribbon wound into a toroidal shape (made into a wound body). For example, if pressure is applied from inside the wound body to spread the wound body, tensile stress can be applied to the wound body. A rigid body or an elastic body can be used to apply tensile stress to the wound body by screwing it inside the wound body, or by putting it inside and expanding it in the radial direction.

The tensile stress applied to the amorphous ribbon may be removed in various ways as appropriate, such as at once at the start of curing, gradually during curing, or all at once after curing. You can choose the method.

Hereinafter, the manufacturing method of the present invention will be explained based on the drawings showing one embodiment. FIG. 1 shows an apparatus for applying tensile stress to a wound body of an amorphous ribbon. As shown in the figure, an elastic body 1 such as rubber having an outer diameter slightly smaller than the inner diameter is placed inside a wound body 2 of an amorphous ribbon, and a compressive stress a is applied to both the upper and lower surfaces of the elastic body. When stretched, the elastic body increases in diameter in the center, so that the ribbon is subjected to tensile stress. Therefore, if resin molding 3 is performed in this state as shown in FIG. 2, a magnetic core with reduced deterioration of magnetic properties can be obtained. Although it is difficult to quantitatively evaluate the stress generated in the above-mentioned ribbon, the outer diameter rI and inner diameter r2 of the toroidal ribbon before it is subjected to stress, and the toroidal shape when it is under stress. Outer diameter of ribbon r, /, inner diameter r
By measuring 2' and 2', it is possible to make a tentative evaluation.

The amorphous magnetic ribbon used in the manufacturing method of this invention is one obtained by a normal manufacturing method.

Furthermore, various resins can be used as molding resins, including epoxy resins that harden at room temperature.

The magnetic core obtained in this way is used by winding it as it is or by cutting it.

Examples and comparative examples are shown below.

(Examples 1 to 5) Amorphous magnetic ribbons (width 1 (in), thickness 25 to 3'
0 pm) was wound 50 times with an inner diameter of 2 ofl to form a toroid, and heat treated according to the composition and use as shown in the table. As shown in FIG. 1, a rod-shaped hard rubber having an outer diameter of 19 mm was placed inside this toroid, and compressive pressure was applied from above and below to deform the rubber. At this time, the inner diameter of the toroid was increased by 0.5fi. In this state, the toroid was molded with an epoxy resin that hardens at room temperature to obtain a magnetic core.

(Comparative Examples 1 to 5) The amorphous magnetic ribbons used in Examples 1 to 5 were processed in the same manner as in Examples 1 to 5, and molded with resin in the same manner without applying stress to form a magnetic core. Obtained.

For each of the magnetic cores obtained in Examples 1 to 5 and Comparative Examples 1 to 5, the iron loss before and after resin molding was measured using the wattmeter method under the conditions shown in Table 1. The results are also shown in the same table. The saturation magnetostriction of each amorphous alloy is also shown in the same table.

(Margin below) As shown in Table 1, the change in iron loss before and after resin molding is smaller for the magnetic core manufactured by the method of the present invention, whereas it is much larger for the magnetic core manufactured by the conventional method. In other words, by applying tensile stress to a wound body of amorphous magnetic ribbon while resin molding, the stress applied to the wound body when the resin hardens is reduced, and a magnetic core with excellent magnetic properties and lower iron loss than before can be obtained. I know that I can do it.

〔Effect of the invention〕

In the manufacturing method of the present invention, the wound body of the amorphous magnetic ribbon is molded with resin while applying tensile stress, so that the stress applied to the wound body when the resin hardens is alleviated, and the magnetic properties are deteriorated. is reduced, it is possible to obtain a magnetic core with low iron loss and excellent magnetic properties.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing how tensile stress is applied to the magnetic core, and Fig. 2 shows a state in which the wound body is molded with resin.
FIG. 1 is a cross-sectional view taken along line X-Y in FIG. 1; 1...Rubber rod 2...Wound body 3...Resin mold a...Direction of stress applied to the rubber b...Direction of stress applied to the wound body Agent Patent attorney Take Hikozuki Matsumoto [From Ito Shishine Hosho Shohaku] November 1, 1980 2, Name of the invention Method for manufacturing amorphous magnetic core 3, Relationship with the case of the person making the amendment Patent applicant Location 1048 Kadoma, Kadoma City, Osaka Prefecture Name Name (583) Matsushita Electric Works Co., Ltd. Representative Iku Kobayashi 4, No agent 6, Specification subject to amendment 7, Contents of amendment (11 Specification, page 7, line 5, ``Watt meter method'') Insert "r (U function method)" between "using".

Claims (1)

[Claims] (1) A method for manufacturing a magnetic core in which an amorphous magnetic ribbon having magnetostriction is wound to form a wound body, and this is molded with resin, the amorphous magnetic core characterized by resin molding while applying tensile stress to the wound body. Manufacturing method.