JPS61180410A - Manufacture of iron core - Google Patents

Abstract

PURPOSE:To suppress the rise in temperature of the corner parts of an iron core by a method wherein a magnetic material is provided between the layers of thin plates located at the corner parts of the iron core consisting of amorphous magnetic alloy thin plates, and an annealing is performed using the heat generated by the iron core itself. CONSTITUTION:The sheet-like insulating materials 13, having the width almost the same as that of the amorphous magnetic alloy thin plates 12, are inserted between the layers of the thin plates 12 every time the amorphous magnetic alloy thin plate 12 is wound by the prescribed number of turns. When an annealing is performed on the wound core 11 for the purpose of removing a distortion, a high frequency AC current is applied to an excitation coil 14. An eddy current runs on the thin plates 12, and the temperature of the thin plates goes up. As a result, an annealing is performed by raising the temperature of the entire wound core 11 to the suitable annealing temperature with a uniform temperature distribution, thereby enabling to restore the intrinsic excellent magnetic characteristics of the amorphous magnetic alloy thin plates 12.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method of manufacturing an iron core made of an amorphous magnetic alloy plate used in a transformer, etc., by annealing the iron core.

[Technical background of the invention and its problems]

Recently, consideration has been given to using amorphous magnetic alloy plates as materials for wound cores used in transformers and the like. The amorphous magnetic alloy plate is made of metals (Fe, Co, etc.).

It is manufactured using an ultra-quenching method with main components of N1, etc.) and semimetallic elements (B, C, St, P, etc.), and has lower iron loss (loss) than silicon steel sheet, which is the conventional core material. is 1/3
It is as small as ~1/4 and has excellent magnetic properties.

However, since the amorphous magnetic alloy plate is manufactured by an ultra-quenching method, its magnetic properties are extremely degraded due to distortion during rapid cooling, such as increased core loss, and the originally excellent magnetic properties cannot be obtained. For this reason, iron cores made of amorphous magnetic alloy plates are subjected to strain relief annealing after core assembly to remove the strain on the amorphous magnetic alloy plates, thereby reducing iron loss and reducing the inherent magnetic properties of amorphous magnetic alloys. Efforts are being made to restore the characteristics. This annealing is a method for improving magnetic properties by placing an iron core in a magnetic field to impart magnetic anisotropy.

In this case, the range of appropriate annealing temperature conditions for the amorphous magnetic alloy thin plate is narrow. For example, METGLAS260582 (trade name) manufactured by Allite 0, USA, which is a typical amorphous magnetic material, has an annealing temperature of about 400°C and a narrow temperature range of ±15°C, as shown in FIG. Further, the required annealing time is short; if this time is long, the crystallization of the amorphous magnetic alloy thin plate will proceed. Therefore, in order to annealing the amorphous magnetic alloy thin plate to remove strain without impairing the excellent magnetic properties inherent to this material, each part of the iron core must be uniformly annealed within the appropriate annealing temperature range in a short time. It is necessary to heat it to

Conventionally, an external heating method has been adopted for strain relief annealing of an iron core made of an amorphous magnetic alloy thin plate. That is, the first
As shown in Fig. 1, a magnetic field coil 3 for applying a magnetic field is attached to an iron core 7, which is a wound iron core formed by winding, for example, an amorphous magnetic alloy thin plate 2.
This iron core 1 is housed inside a constant temperature bath 4 whose heat source is an electric heater (not shown). And DC power supply 5
The annealing is performed by applying a magnetic field to the iron core 1 by applying a direct current to the magnetic field coil 3, and by heating the iron core 1 by raising the inside of the constant temperature bath 4 to a predetermined annealing temperature by the heat generated by the electric heater.

However, in such an annealing method, the iron core 1
Since it is heated from the outside by the radiant heat of the electric heater, it is not possible to properly heat the inside of the iron core 1, and there is a temperature distribution between the surface of the iron core 1 and the inside of the iron core 1.

Becomes non-uniform. FIG. 12 is a diagram showing the relationship between heating time and temperature rise of each part of the core when a nine-wound core of core type T60 is heated to an annealing temperature of 400'C by a conventional annealing method. FIG. 13 is an explanatory diagram showing the locations where the temperature was measured in the iron core. In FIG. 13, point A indicates the central portion of the iron core 1 in the direction of the thickness of the thin plate, point B indicates the outer periphery in the direction of the thickness of the thin plate, and six points indicate the outer surface of the iron core 1. Note that point D indicates the internal space of the thermostatic chamber 4. According to FIG. 11, when 3 hours have elapsed since heating the iron core 1,
At point B, the temperature rises to about 280℃, but at point A, the temperature rises to about 280℃.
The temperature increases only up to 30°C, creating a temperature difference of about 50°C between the two.

Furthermore, the temperature at six points of iron core 1 rose to about 390°C, creating a temperature difference of about 160°C with point A.

As described above, the temperature rise on the surface of the iron core 1 is larger than that inside the iron core 1, and the temperature distribution becomes non-uniform throughout the iron core 1. In order to bring the entire core 1 to a uniform temperature, the core 1 must be heated for an even longer period of time, and as a result, the surface of the core 1, where the temperature rises quickly, is exposed to high temperatures for a long time, causing amorphous The magnetic properties of the magnetic alloy thin plate deteriorate. Therefore, according to the conventional annealing method, the iron core! There is a problem in that it is difficult to heat the whole to a uniform temperature in a short time, and as a result, the magnetic properties of the amorphous magnetic alloy thin plate 2 deteriorate and the original excellent magnetic properties cannot be restored.

Recently, however, a high frequency current for excitation is passed through a coil wound around an iron core made of an amorphous magnetic alloy thin plate to excite the iron core.
A method has been developed in which the iron core itself is annealed by generating heat and increasing its temperature by the loss that occurs in the iron core due to this excitation.

This method can raise the temperature of the wound core more uniformly than the conventional annealing method using external heating, and most of the work of winding transformer coils and assembling the transformer contents can be done before annealing. This process can be carried out as a process, and has the advantage that the handling of the iron core after the amorphous magnetic alloy thin plate becomes brittle due to annealing can be minimized, thereby reducing the chance of external force being applied to the amorphous magnetic alloy thin plate.

However, even in such an annealing method using high frequency excitation, it is still insufficient to uniformly raise the temperature of the entire wound core. FIG. 14 is a diagram showing the relationship between the temperature rise of each part of the core and the excitation time when the temperature of the wound core is raised by the conventional high-frequency excitation annealing method.

FIG. 15 is an explanatory diagram showing temperature measurement points in the circumferential direction of the wound core in the diagram of FIG. 14. In this figure, point Each leg is shown. Note that each point is a central portion of the wound core 1 in the thin plate winding thickness direction. According to FIG. 14, when approximately 30 minutes have elapsed after high-frequency excitation of the wound core 1, the temperature rises to 400°C at the corner Y point of the wound iron core 1, 370°C at the silicate iron part X point, and rises to 370°C at the leg part. At the two points, the temperature increases only up to 300°C, and in particular, there is a temperature difference of about 100°C between the Y point and the two points. In this way, even in the high-frequency excitation annealing method, the degree of temperature rise at the corner part of the wound core is high and the temperature distribution becomes uneven throughout the wound core, so the internal strain of the amorphous magnetic alloy thin plate cannot be sufficiently removed. There was a problem in that it was difficult to obtain an iron core with excellent magnetic properties.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and it provides a wound core that can exhibit the excellent magnetic properties inherent to an amorphous magnetic alloy by successfully performing strain relief annealing on a wound core made of an amorphous magnetic alloy thin plate. The purpose of the present invention is to provide a method for manufacturing an iron core that can be manufactured using the following methods.

[Summary of the invention]

The method for manufacturing an iron core of the present invention is to provide a magnetic material between the thin plate layers at the corners of a wound iron core made of amorphous magnetic alloy thin sheets, and to excite the wound iron core by passing a high-frequency current through a coil wound around the wound iron core. By performing annealing using the heat generated by the core, the temperature increase at the corner portions of the core is suppressed and the wound core can be annealed with a uniform temperature distribution.

[Embodiments of the invention]

Embodiments of the present invention illustrated in the drawings will be described below.

FIGS. 1 and 2 show an embodiment of the method of the present invention, and this embodiment is intended for the case where two sets of wound cores are lined up and subjected to strain relief annealing. However, in this embodiment, a sheet-like insulating material is used as the insulating material provided at the corner portion of the wound core.

First, as shown in FIG. 2, a strip-shaped amorphous magnetic alloy thin plate 12 is wound into a rectangular shape to form an uncut type or one turn cut type (the uncut type is shown in the drawing) wound core 11. When forming this wound core 11, each time the amorphous magnetic alloy thin plate 12 is wound a predetermined number of turns, the wound core 11 is
A sheet-shaped insulating material 13 having approximately the same width as the amorphous magnetic alloy thin plate 12 is inserted between the layers of the thin plate 12 at each corner of the thin plate 12 .

As a result, at each corner of the wound core 11, the sheet-like insulating material 13 is interposed between the wound layers of the amorphous magnetic alloy thin plate 12 at a plurality of locations at equal intervals in the direction of the winding thickness. In addition, since the distance between adjacent corner parts of the wound core 11 with the silicate iron part sandwiched therebetween is short, in this embodiment, the sheet-like insulating material 13 is applied to each corner part of the wound core 11 and the silicate iron part sandwiched between these corner parts. This is provided in common across all departments. This is to enable the sheet-like insulating material 13 to be easily inserted between the eyebrows of the amorphous magnetic alloy thin plate 12 when forming the wound core 11. The sheet-like insulating material 13 is made of an insulating material that can withstand the annealing temperature of an amorphous magnetic material of 400°C, such as a polyimide film (with a heat resistance temperature of about 470°C,
Manufactured by Ube Industries, product name Upilex) and ceramics
-z mother (heat resistant temperature approx. 700℃, manufactured by Asahi Asbestos, product name:
Ceramics fine paper 4) or inorganic coating treatment (MgO treatment, etc.) on amorphous magnetic alloy thin plate
Use one that has been treated with

Next, as shown in FIG. 1, before the annealing step, the two wound cores 11 are arranged side by side, and a transformer coil 19 is commonly attached to the inner leg of each wound core 11.

Next, as shown in FIG. 1, the excitation coils 14 are wound around the outer legs of each core 11 in opposite directions. The number of turns of the excitation coil 14 is set appropriately. The excitation coil 14 is connected to a high frequency AC power source 16 and a DC power source I7 via a changeover switch 15. In the figure, 18 is a voltage regulator that adjusts the voltage of the high frequency AC power supply 16.

When strain relief annealing is to be performed on the wound core 11, the excitation coil 14 is connected to the high frequency AC power supply 16 by the changeover switch 15, the voltage is adjusted by the voltage regulator 18, and the high frequency AC current is applied to the excitation coil 14. Flow. The frequency of this alternating current is selected to be 500 degrees or more, for example, 2 to 7 kHz. When an alternating current is passed through the excitation coil 14, an eddy current flows through the amorphous magnetic alloy thin plate 12 in the wound core 11 due to the generation of magnetic flux, and heat is generated in the amorphous magnetic alloy thin plate 12 due to power loss accompanying this eddy current. temperature rises. When the temperature of the amorphous magnetic alloy thin plate 12 rises to the appropriate annealing temperature of 400'C, the voltage of the alternating current is adjusted by the voltage regulator 18 to maintain the temperature at 400'C for a certain period of time. In this way, the amorphous magnetic alloy thin plate 12 of the entire wound core 1 is heated to an annealing temperature of 400° C. in a short time with uniform temperature distribution.

Thereafter, the excitation coil 14 is switched and connected from the AC power source 16 to the DC power source 17 by operating the changeover switch 15. As a result, the wound core 11 is stopped from being excited by alternating current and starts cooling.

At the same time, a DC current flows from the DC power supply 17 to the exciting coil 14, forming a magnetic field with respect to the wound core 1. In this way, the wound core 1 is cooled in the magnetic field.

Note that after the annealing of the wound core 11 is completed, the excitation coil 14
from the winding core 11. Note that the sheet-like insulating material 13
Leave it attached to the wound core 1.

However, when the iron core 11 is annealed in this manner, the sheet-shaped insulating material 13 is placed between the thin plate layers at the corner of the wound core 1, which reduces the loss generated at the corner and generates less heat. Therefore, the temperature difference in the circumferential temperature distribution of the wound core 11, especially the temperature difference between the corner portion and the leg portion, becomes small, and the temperature distribution becomes uniform. Therefore, the original excellent magnetic properties of the amorphous magnetic alloy thin plate 12 can be restored by annealing the entire wound core 11 with a uniform temperature distribution at an appropriate annealing temperature of 400°C. In addition, the loss generated in the silicate iron portions sandwiched between each corner portion is also reduced, which helps to make the temperature distribution of the wound core 11 uniform. An example of experimental results shows that when a sheet-like insulating material is inserted every 30 to 40 turns of an amorphous magnetic alloy thin plate in the corner of a wound core and high-frequency excitation annealing is performed on the wound core, The maximum temperature difference in the circumferential direction of the core could be reduced to 20 degrees Celsius or less, and the core loss of the wound core could be improved by about 15 inches compared to one without inserting sheet-shaped insulating material.

These points will be explained in more detail. If the iron loss (W/kp) generated in an iron core wound with an amorphous magnetic alloy thin plate, that is, before strain relief annealing, is separated into hysteresis loss and eddy current loss (calculated using an actual measurement example), When the iron core is excited at commercial frequencies (5011z, 60Hz), hysteresis loss accounts for most of the loss.
When the excitation frequency becomes 5 KHz, the ratios of both become approximately equal. The core loss of amorphous magnetic alloy thin plates is reduced by applying appropriate heat treatment. The effect of heat treatment is particularly large in the high frequency range. This reduces hysteresis loss by removing the strain caused by rapid cooling during the production of the amorphous magnetic alloy thin sheet through heat treatment, and also causes the magnetic domains to become finer due to the fine crystal phase created in the amorphous magnetic alloy thin sheet through heat treatment. is,
This is because the abnormal eddy current loss generated near the domain wall is reduced.
It is said that the latter effect is large in the high frequency range.

The following is a general formula for determining the iron loss of a transformer core.

Iron loss W/y = Kl f Bm + 2f” Bm
"t" where f = frequency (Hz) Bm = maximum magnetic flux density t = thickness of magnetic material K1 + Kttn: constant In the above equation, the hysteresis loss shown in the previous section increases in proportion to the frequency, but the eddy current loss in the latter section Proportional to the square of the frequency. For these reasons, in strain relief annealing in a high frequency range, the influence of eddy current loss becomes large. Particularly in a rectangular wound core, the surface pressure of the amorphous magnetic alloy thin plate at a portion of the corner is higher than that of the core leg due to the tightness of the thin plate. For this reason, since the amorphous magnetic alloy thin plate has a low glabellar resistance due to the lack of an insulating film, the eddy current in a part of the corner increases as the frequency increases, leading to worsening of iron loss. The present invention has focused on this phenomenon, and by providing an insulating material between the thin plate layers at the corner portions of the wound core, the glabellar resistance at the corner portions is increased and eddy current loss is reduced.

Next, the provision of a sheet-like insulating material between the layers of the amorphous magnetic alloy thin plate at a predetermined interval in the thickness direction of the thin plate at the corner portion of the wound core will be explained. FIG. 3 shows a state in which the wound core 11 is divided into a plurality of blocks from a block to g block in the direction of the winding thickness. Note that the a block is the innermost circumferential side of the iron core, and the g block is the outermost circumferential side. Then, a search coil (not shown) is wound around the wound core to set the frequency to 5 K.
The wound core was excited at Hz, and the magnetic flux distribution in the thickness direction of the wound core was measured. An example of the measurement results is shown in the diagram of FIG. In this diagram, B is the magnetic flux density of each divided block, Bm
represents the magnetic flux density of the entire wound core. When the magnetic flux density is 0.3 tesla), the block on the inner circumference of the wound core has a high magnetic flux density, but when the magnetic flux density is 0.7 tesla), the difference in the magnetic flux density between the inner and outer circumferential sides of the wound iron core is high. There are almost no

In the high-frequency excitation annealing method, the core is excited by a somewhat high magnetic flux density (around 0.3 to 1.0 Tesla) in order to raise the temperature due to the loss of the core itself, so the magnetic flux density in the direction of the winding thickness of the core is increased. It can be considered constant. Therefore, it can be said that the sheet-like insulating material provided at the corner portion of the wound core may be placed between the thin plate layers of approximately equal winding thickness.

5 to 7 show other embodiments of the present invention, and the same parts as in FIGS. 1 and 2 are designated by the same reference numerals. In this embodiment, an insulating film is formed on the surface of an amorphous magnetic alloy thin plate 120 forming the wound core 11 as an insulating material provided at the corner portion of the wound core.

First, as shown in FIG. 6, a strip-shaped amorphous magnetic alloy thin plate 1
2 is wound to form a rectangular wound core 11 in which insulating layers 20 are formed on both sides of the amorphous magnetic alloy thin plate 11 of each wound layer at the valley corner portion. This wound core 1 is formed, for example, by the method shown in FIG. The amorphous magnetic alloy thin plate 12 wound in a hoog shape is fed out and an inorganic oxide coating solution 21 is applied.
It passes above the bathtub 22 containing the water.

Above this bathtub 22 is a presser row 2 that moves up and down intermittently.
23 is provided, and when the pressing roller 23 descends, the portions of the amorphous magnetic alloy thin plate 12 corresponding to each corner of the wound core 11 are pushed down and immersed in the oxide film solution 21 in the bath 22, and the amorphous A solution 21 is applied to both surfaces of the magnetic alloy thin plate 12. Roughly pass the amorphous magnetic alloy thin plate 12 through a drying device 24 to dry the oxide film solution 21 adhering to the thin plate 12 to form an inorganic oxide film, that is, an insulating film 20.
After that, the amorphous magnetic alloy thin plate 12 is passed through a winder 25.
Wind it into a rectangular shape. In this way, the amorphous magnetic alloy thin plate 12 is wound to form the wound core 1 while sequentially forming the insulating coating 20 on both sides of the portion corresponding to each corner of the wound core 11. An insulating coating 20 is formed between the layers of each amorphous magnetic alloy thin plate 12 at each corner. In this embodiment, in order to facilitate the formation of the insulating coating 20 on the amorphous magnetic alloy thin plate 12, the insulating coating 20 is formed over the silicate portion of the wound core 11 and each corner portion located on both sides thereof. I am asking you to do so.

Next, as shown in FIG. 5, two sets of wound cores 1 are placed side by side, and a transformer coil 19 is attached to the inner leg of the wound core 11.
Further, an excitation coil 14 is wound around the outer leg of each winding core 11, and this excitation coil 14 is connected to an AC power source 16 and a DC power source 17 via a changeover switch 15. Then, the wound core 11 is excited at high frequency in the same manner as in the embodiment described above,
Due to the loss that occurs in the wound core 11 due to this excitation, the wound core 1
1. Annealing is performed by generating heat.

Note that this annealing is performed in an inert gas atmosphere such as N, gas, or Ar gas.

Therefore, when annealing is carried out by the method of this embodiment, since the insulating coating 20 exists between the layers of the amorphous magnetic alloy thin plate 12 at the corner part of the wound core 1, the loss generated at the corner part is reduced. Since heat generation is suppressed, the temperature distribution of the entire wound core 11 can be made uniform and annealing can be performed at a proper annealing temperature of 400°C. An example of experimental results shows that the maximum temperature difference in the circumferential direction of the core can be reduced to 20 degrees Celsius or less, and the core loss of the wound core can be improved by about 17 inches compared to a wound core without insulation coating treatment. In addition, since the insulating coating 20 is partially formed on the amorphous magnetic alloy thin plate Z2 at the corner part where the generated loss is small,
The space factor is better than when the amorphous magnetic alloy thin plate 12 of the entire wound core 1 is treated with an insulating coating.

FIG. 8 shows an example in which an insulating coating 20 is formed on one side of the amorphous magnetic alloy thin plate 120 of each wound layer in the corner portion of the wound core 11.

FIG. 9 shows insulating coatings 20 on both or one side of amorphous magnetic alloy thin plates 120 located at a plurality of locations at predetermined intervals (for example, 10 to 20 turns) in the winding thickness direction at the corners of the wound core 11. An example is shown below.

Similar effects can be obtained even when an insulating film is formed as shown in FIGS. 8 and 9.

〔Effect of the invention〕

As explained above, according to the method for manufacturing the wound core of the present invention, the wound iron core made of amorphous magnetic alloy thin plate can be annealed by raising the temperature with a uniform temperature distribution. You can get iron core.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing one embodiment of the manufacturing method of the present invention, Fig. 2 is a perspective view showing a wound core in the same embodiment, and Fig. 3 is an explanatory diagram showing a state where the wound iron core is divided in the direction of the winding thickness. 4 is a diagram showing the temperature distribution in the winding thickness direction of the wound core, FIG. 5 is an explanatory diagram showing another embodiment of the manufacturing method of the present invention, and FIG. 6 is a diagram showing the winding core in the same embodiment. FIG. 7 is an explanatory diagram showing the manufacturing process of the wound core of the same embodiment, FIGS. 8 and 9 are perspective views showing modifications of the wound core of the same example, and FIG. 10 is an amorphous core. Fig. 11 is an explanatory diagram showing the conventional external heating annealing method, and Fig. 12 shows the temperature rise in each part of the wound core when annealing is performed by the conventional external heating annealing method. Fig. 13 is an explanatory diagram showing the temperature measurement points of the wound core, Fig. 14 is a diagram showing the temperature rise of each part of the wound core when annealed by the conventional high-frequency excitation annealing method, and Fig. 15 is a diagram showing the temperature measurement points of the wound core. FIG. 2 is an explanatory diagram showing temperature measurement points. 11...Wound core, 12...Amorphous magnetic alloy thin plate, 1
3... Sheet-shaped insulating material, 14... Excitation coil, 16
...AC power supply, 17..DC power supply, 19..Transformer coil, 2θ..Insulating coating. Applicant's representative Patent attorney Takehiko Suzue 1vA Fig. 3 Fig. 4 Block Fig. 5 Fig. 6 Fig. 7 *sm 191a $ Fig. 10 Baking temperature C) 1111 Fig. 12 Time (combined) Figure 13 Figure 14 Between vff Figure 15

Claims (3)

[Claims] (1) providing an insulating material between the layers of the amorphous magnetic alloy thin plate in the corner portion of the wound core made of the amorphous magnetic alloy thin plate;
Manufacturing an iron core characterized in that an alternating current is passed through a coil wound around the wound iron core to excite the wound iron core, and the wound iron core itself is heated and heated by heat generation due to a loss generated in the wound iron core due to this excitation to perform annealing. Method. (2) The method for manufacturing an iron core according to claim 1, wherein the insulating material is in the form of a sheet. (3) The method for manufacturing an iron core according to claim 1, wherein the insulating material is an insulating coating formed on the surface of the amorphous magnetic alloy thin plate forming the wound core.