JPS62277709A - Manufacture of core - Google Patents

Abstract

PURPOSE:To remove an oxide layer formed on the end surface of a core, and to obtain the core having excellent magnetic characteristics by annealing the core consisting of an amorphous magnetic thin-band and giving the core vibrations by applying a large magnetic field. CONSTITUTION:Stress relief annealing is executed to a wound core 1 formed by winding an amorphous magnetic thin-band by an annealing device. An AC power supply 5 is connected to an exciting coil 3 through a high-frequency power amplifier 4, and the wound core 1 is excited by high frequency. The magnetic field of a magnetic flux density region larger than the service magnetic field of the wound core 1 or a high frequency region is applied to an oxide layer 6 generated on the end surface of the wound core 1 on annealing and the oxide layer 6 excited, thus easily peeling the oxide layer 6. Conditions in which the oxide layer on the end surface of the wound core 1 can be peeled by the adhesion of the oxide layer, the thickness (it differs by the quantity of oxygen and moisture content in an inert gas on annealing) of the oxide layer formed, exciting vibrating force (the quantity of magnetostriction differs by the magnitude of exciting frequency and magnetic flux density), etc. differ in the oxide layer.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Object of the Invention] (Field of Industrial Application) The present invention relates to an iron core made of amorphous magnetic ribbon used in induction devices such as transformers and reactors. The present invention relates to a WA manufacturing method, and particularly to improving magnetic properties.

(Prior art) In recent years, attempts have been made to use amorphous magnetic ribbon, which has excellent magnetic properties, as core materials for induction equipment such as transformers, instead of conventional silicon steel sheets, permalloy, ferrite, etc. It is being This type of amorphous magnetic ribbon is annealed in an inert gas to improve its magnetic properties in order to remove residual strain during manufacture and residual stress during core removal. Although annealing of an amorphous magnetic ribbon varies depending on the type of ribbon, it is said that annealing at about 400° C. for about 2 hours is appropriate.

On the other hand, when an iron core made of an amorphous thin ribbon is annealed, an oxidized layer is formed on the end face of the iron core due to impurities in the inert gas, and the current layer may increase if the iron core is used as is. In particular, when iron-based amorphous magnetic materials are used together with iron cores for high-frequency applications, the annealing temperature is high and the annealing time is long to precipitate fine crystal grains in order to reduce the abnormal current layer. However, in this case, the formation of an oxidized layer on the end face of the iron core is further promoted, and a problem arises in that the wax current layer increases due to interlayer short circuits and the magnetic properties deteriorate. This oxide layer has strong adhesion and cannot be removed during normal use of the core.

(Problems to be Solved by the Invention) As described above, in the iron core made of the iron-based amorphous magnetic ribbon, an oxide layer is formed on the end face of the iron core due to impurities in the inert gas used during annealing. This oxide layer short-circuits the ribbons and increases eddy current loss in the core, so even if the core is manufactured using amorphous magnetic ribbons, the excellent magnetic properties inherent to amorphous magnetic materials cannot be obtained. The problem was that there was no.

The present invention aims to provide a method for manufacturing an iron core that removes an oxide layer formed on the end face of the iron core when an iron core made of an amorphous magnetic ribbon is annealed to remove strain, thereby obtaining an iron core with excellent magnetic properties. purpose.

[Structure of the Invention] (Means for Solving the Problems) An iron core made of an amorphous magnetic ribbon undergoes an oxidation reaction between trace amounts of oxygen and moisture in an inert gas used during annealing and Fe atoms of the iron core. An oxide layer is formed on the end surface. The inventors discovered that this oxide layer can be peeled off and removed by applying vibration to the iron core. Therefore, the present invention focuses on the large magnetostriction of an amorphous magnetic ribbon, and is characterized by applying a large magnetic field to the core after annealing the core made of the amorphous magnetic ribbon to give vibration to the core. It is something.

(Function) When a large magnetic field is applied to an iron core made of an amorphous magnetic ribbon, large excitation vibrations are generated due to the magnetostriction of the amorphous magnetic ribbon, and the oxide layer formed during annealing of the iron core is peeled off.
Eddy current loss caused by short circuits in the living room of the ribbon can be reduced.

(Example) 1 to 3 show an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a wound core formed by winding an amorphous magnetic ribbon, which has been subjected to strain relief annealing using an annealing device (not shown). Strain relief annealing is approximately 4
This is carried out by heating at a temperature of 00° C. for about 2 hours in an inert gas.

FIG. 2 is a cross-sectional view taken along the line II-II of the wound core 1 shown in FIG. It shows. An excitation coil 3 is wound around this wound core 1 as shown in FIG. 1, and an AC current 11i5 is connected to this excitation coil 3 via a high frequency power amplifier 4 to excite the wound iron core 1 with high frequency. In this case, frequency and magnetic flux! If the magnetostriction of the core is increased by increasing the magnetostriction, it is possible to provide excitation vibrations larger than those generated in a magnetic field when the wound core 1 is used as a transformer core.

FIG. 3 shows the relationship between frequency and magnetostriction at a magnetic flux density of 1.3 T (Tesler) of the semi-iron core 1.

It is observed that when the magnetic flux tortuosity is constant, the magnetostriction increases as the frequency increases.

FIG. 4 shows the relationship between the magnetic flux density and magnetostriction of the wound core at a frequency of 400 l-1z. It is observed that the magnetostriction increases rapidly as the magnetic flux density increases. Since magnetostriction corresponds to the amount of expansion and contraction of the core that occurs when the core is excited, that is, the amplitude of the excitation vibration, as mentioned above, increasing the magnetostriction increases the excitation vibration of the core 1, and this excitation vibration causes oxidation. Peeling of layer 6 becomes possible.

That is, the oxide layer 6 generated on the end face of the wound core 1 during annealing
cannot be removed by small excitation vibrations generated in the working magnetic field of the iron core, but the oxide layer 6 can be easily peeled off by applying and excitation a magnetic field in a magnetic flux density region or high frequency region larger than the working magnetic field of the wound iron core 1. Become.

The oxidized layer on the end face of the wound core 1 has the following properties: (a) Adhesion of the oxidized layer (b) Thickness of the formed oxidized layer varies depending on annealing, oxygen m in the inert gas, and water intake) (C) Excitation Since the conditions for peeling differ depending on the vibration force (the amount of magnetostriction varies depending on the excitation frequency and the magnitude of magnetic flux density), etc., the magnitude of the magnetic field applied to the wound core 1 may be adjusted as appropriate even if the magnitude of the magnetic field applied to the wound core 1 is greater than or equal to the working magnetic field of the wound iron core 1. You need to choose.

FIG. 5 is an example of an experiment on the relationship between the iron loss (measured at a measurement frequency of 4 KHz) of the wound core and the magnetic flux density before and after removing the oxide layer. The dotted line in the figure shows the iron loss before applying excitation vibration to the wound core, and the solid line shows the iron loss value after applying excitation vibration.

The excitation conditions were a frequency of 4001-1z, a bundle density of 1.4 teeth, and a duration of 5 minutes. As shown by the solid line in Figure 5, the wound core subjected to excitation vibration has an iron loss of approximately 3 at each magnetic flux density.
It has decreased by 0%, and it can be seen that the effect of applying excitation vibration to the iron core is produced.

In the above embodiments, a wound core is used as an example, but a laminated core can also be used.

[Effects of the Invention] As explained above, according to the method of manufacturing an iron core according to the present invention, the oxide layer formed on the iron core made of amorphous magnetic ribbon can be removed, so that eddy current loss can be reduced and magnetic properties can be improved. It is possible to obtain an excellent iron core.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a method of manufacturing an iron core according to an embodiment of the present invention, Fig. 2 is a sectional view showing the state of the wound core after annealing, and Fig. 3 shows the relationship between magnetostriction and excitation frequency. 4 is a diagram showing the relationship between magnetostriction and magnetic flux 3 degrees, and FIG. 5 is a diagram showing changes in iron loss before and after applying excitation vibration in the method of the present invention. 1...Wound iron core, 2...Amorphous magnetic ribbon, 3...
Excitation coil, 4...high frequency power amplifier, 5...
AC power supply, 6... oxidation layer. Agent Patent attorney t Rules Noriyuki Chika Hiroshi Mitsumata Collection 11A Figure 2 r @ Agriculture class (Hz) Figure 3 Figure 4

Claims (2)

[Claims] (1) A method for manufacturing an iron core, which comprises annealing an iron core made of an amorphous magnetic ribbon and then vibrating the iron core by applying a magnetic field large enough to peel off an oxide layer formed on the iron core. (2) The method for manufacturing an iron core as set forth in claim 1, wherein the frequency of the applied magnetic field is equal to or higher than a commercial frequency.