JPS62226611A - Annealing of iron core - Google Patents

Abstract

PURPOSE:To obtain original excellent magnetic characteristics of an amorphous magnetic alloy plate while making excitation conditions good and stable by providing a coil of greater inductance than that of an iron of an iron core in a high frequency circuit for exciting the iron core. CONSTITUTION:A coil 14 is temporarily and adversely wound around the outer leg of a transformer which has a coil 13 around the central leg of the wound core 11 of amorphous magnetic alloy plates. A high frequency current is applied to the coil 14 by selecting the tap of an inductance coil 18 which has greater inductance than the inductance L of the wound core 11. A temperature is raised to nearly 400 deg.C by the generation of heat of the wound core 11. The total inductance of an excitation circuit is made L1+L2 due to the existence of the coil 18, the change is reduced, the excitation conditions are made stable and the temperature is raised to an appropriate temperature for annealing at nearly 400 deg.C. After the coil 14 is kept at 400 deg.C for a required time, the power is switched 15 to a D.C.power source 17, the coil 14 is cooled in a magnetic field and is removed after annealing. Since the change of inductance by the reduction of permeability of the iron core due to the rise of the temperature can be ignored, the annealing can be carried out effectively and excellent magnetic characteristics can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [-1 of the Invention (Field of Industrial Application) The present invention relates to a method of annealing an iron core made of an amorphous magnetic alloy plate used in transformers and the like.

(Prior Art) In recent years, consideration has been given to using amorphous magnetic alloy plates as materials for wound cores and laminated cores used in transformers and the like. Amorphous magnetic alloy plates include metals ([C, Co, Ni, etc.) and 1' metal modern (B, C.

It is manufactured using an ultra-quenching method with main ingredients such as s; It is small in size and its magnetic properties are inferior.

However, since the amorphous v11f1 alloy root is manufactured using an ultra-quenching method, the strain during the rapid cooling causes an increase in iron 10, which deteriorates the magnetic properties to such an extent that it remains as it is (J, the original excellent In this case, the iron core made of the amorphous 71 magnetic alloy plate is subjected to strain relief annealing to the iron core assembly 1 (to remove the strain of the amorphous magnetic alloy plate, and to reduce the iron 1Ω). The aim is to restore the magnetic 1'I properties of amorphous magnetic alloy plates such as.

This annealing is a method of improving the magnetic properties by imparting unique characteristics to the iron core.

Therefore, when performing this annealing, the following C is important. The amorphous magnetic alloy plate t has a narrow annealing strip 1'1, and if the temperature inside the core is kept at a uniform temperature of 1α, the magnetic properties will deteriorate due to thermal stress. Therefore, it is impossible to restore the original excellent magnetic properties of Ti.

In addition, since the amorphous magnetic alloy plate has the property of becoming brittle in Vl, when handling the core after annealing, the amorphous 't1
[4] The steel alloy plate may crack or break due to external force, causing dielectric breakdown during use of the transformer, which is not desirable in terms of the quality of the iron core. Therefore, it is necessary to assemble the core before annealing, reduce the number of assembly steps after annealing, and reduce the number of regular meetings where external force is applied to the amorphous magnetic alloy plate.

Conventionally, the method of annealing an iron core made of 31 crystalline magnetic F1 alloy plate was to heat the iron core in a constant temperature oven using an external heat source such as an electric heater. Because the hot stone distribution on the surface and inside of the core becomes uneven, the magnetic properties of the amorphous magnetic alloy plate that makes up the core deteriorate due to thermal stress, and it may not be possible to exhibit the original (It loss characteristics). In addition, in order to heat the iron core to a predetermined annealing temperature of about 400°C using an electric heater, it is heated inside a thermostatic oven to reach the crystallinity.
If the iron core around which the transformer coil is wound is placed inside a constant temperature oven and annealed, the transformer coil and the core are heated together with 400 liters from the outside.
It will be heated to ℃. However, in general
: Insulator used in the core coil (1. The heat resistance limit is low, and if heated to a temperature of 400°C, the insulator will be damaged and become impractical. For this reason, the transformer is used in the core in the process after annealing. The coil will be wound, but as mentioned above, the iron core after annealing will be accompanied by the embrittlement phenomenon of the amorphous magnetic alloy plate, so if the assembly work of winding the coil around the iron core is performed at 1η of annealing, , the chance that the amorphous 71 magnetic alloy plate will break IQJ due to external force will increase, and the quality of the iron core will deteriorate.

Recently, however, a high frequency current for excitation is passed through a coil wound around an iron core made of an amorphous magnetic alloy plate to excite the iron core.
Due to this excitation, the 1 (1) produced in the iron core (1) is a method of annealing the iron core itself by heating it to a heat-generating shift temperature (Japanese Patent Application No. 159-39506).

This method allows most of the transformer coil winding work (N'') and the assembly work of the transformer contents to be performed as a pre-annealing process. This has the advantage of minimizing the amount of handling required and reducing the chances of external force being applied to the amorphous fi1 magnetic alloy plate.

<Problems that Ming is trying to solve) However, in this high-frequency excitation annealing method, if the temperature of the core exceeds about 300°C due to high-frequency excitation, the permeability of the core and the saturation magnetic flux density will decrease, causing problems in the excitation circuit. Inductance decreases and matching devices for high frequency power sources such as high frequency generators and high frequency inverters ([, C circuit)
yA such as poor balance and rapid increase in reactive power.
This causes problems such as γ1 tending to saturate due to temperature, and conversely, the iron core heats up rapidly. - There were cases where the original excellent magnetic properties of the rjl-crystalline 71 magnetic tit alloy plate were not maintained.

The present invention has been made in view of the above circumstances, and is capable of efficiently annealing the amorphous alloy sheet.
The first objective is to provide an annealing method for an iron core that fully exhibits the improved magnetic properties.

[Structure of the Invention] (Means for Solving the Problems) The method for annealing an iron core of the present invention is as follows: lIl:' An excitation alternating current is passed through a coil wound around an iron core made of a crystalline magnetic alloy plate to annealing the iron core. In the method of exciting the iron core and annealing it by depleting the heat generation temperature of the iron core white body by the loss generated in the iron core due to this excitation, a circuit that excites the iron core at high frequency is provided with an inductance [21] to the right of the iron core. It is characterized by reducing the influence of the decrease in inductance due to the temperature of the iron core.

(Function) Amorphous magnetic alloy plate J: The magnetic permeability of the iron core rapidly decreases from the time when the temperature exceeds about 300°C, so the inductance becomes smaller. However, in the present invention, since a coil having a large inductance L2 is provided in the excitation circuit, the inductance of the entire excitation circuit is L2.
-1-12 and 41: Since the change in inductance L1 of the iron core is 2 (1), stable excitation conditions are established and the annealing of the iron core can be performed efficiently.

(Example) An embodiment of the present invention will be described below.

FIG. 1 shows an embodiment of the present invention, in which two sets of wound cores 11.11 made of wound amorphous magnetic alloy plates are arranged side by side, and a common center leg of each wound core 11.11 is arranged. The target is the annealing of the iron core of an external iron type transformer around which the transformer coil 13 is wound.

The wound core 11 is formed by winding a band-shaped amorphous magnetic alloy plate 12, and in the pre-annealing process of the wound core 11, two wound cores 11 and 11 are lined up and a common thread is attached to the central leg. The transformer coil 13 is wound around. Each winding core 11.1
A pre-wound coil 14 for passing a high-frequency excitation current is fitted to the outer leg portions of the coils 1, respectively. These pre-wound coils 14 are connected in parallel with their winding directions reversed, and the changeover switch 15
It is switchably connected to a high frequency AC power source 16 and a DC power source 17 via. Between the selector switch 15 and the AC power supply 16, there is an inductance coil 18 having a tap terminal for voltage adjustment, and a matching device consisting of a C circuit. i19 will be established. The inductance coil 18 has a smaller inductance than the inductance of the wound core 11.
1. Due to the decrease in magnetic permeability due to the crystallinity L\'I of 11, the change in the inductance of the excitation circuit is expressed as i+Ii
This is provided to ensure that tn = J, and also as a matching device.
? :119 is an excitation strip (provided to keep the excitation line from being stable).

When annealing the wound core 11.11, C connects the temporary winding coil 14 to the high frequency AC power supply 16 side using the changeover switch 15, connects it to an appropriate tap terminal of the inductance coil 18, and (A high-frequency current (for example, 5t<117) for excitation is passed through the coil 14. A high-frequency current is passed through the temporarily wound coil 14.) As a result of the generation of magnetic flux, the wound iron core 1
At 1.11, a current is generated and the electric power accompanying this eddy current generates heat. When heated, the temperature increases to Dr l = ``;+'.In this case, the loss that occurs in the wound core 11゜11 due to high frequency excitation is almost /v until the temperature of the wound core 11.
However, if the temperature exceeds this temperature, the ifi (41) ratio of the wound core 11 decreases, and the inductance of the excitation vA circuit becomes small, making the excitation conditions unstable. Figure 2 shows the relationship between the temperature and magnetic permeability of the iron core at a frequency of 5 KHz and a magnetic flux density of 1°OT.
It is observed that the magnetic permeability drops dramatically from the time when the core temperature 1α exceeds 300°C. Since the inductance of the iron core is directly proportional to the magnetic permeability as shown in equation (1) below,
When the permeability of the iron core decreases, the inductance of the iron core decreases, and the inductance of the entire excitation circuit also decreases.

! Here, 1-1 is the inductance of the iron core, μ is the magnetic permeability of the iron core, N is the number of turns, ΔS is the cross-sectional area of the iron core, and l is the length of the magnetic path.

Therefore, if the winding core 11 remains as it is, the annealing temperature is 400°C.
Near 1 power C temperature L5'? As the magnetic permeability of the wound core 11 approaches 1 and its inductance L1 decreases, the resistance of the excitation circuit becomes only the resistance of the pre-wound coil 14, so a large current flows through the excitation circuit and the excitation conditions become unstable. It may become.

However, in the present invention, since the excitation circuit is provided with a coil 18 having an inductance 1-2 larger than the inductance L1 of the wound core 11 and 1° to the right, the inductance of the entire excitation circuit becomes L+L2, and the temperature of the wound core 11 increases. Since the change in inductance becomes small, the excitation conditions are stabilized, and the wound core 11 is heated to an appropriate annealing temperature of 400'C.

Note that the flange of the inductance coil 18 has an annealing temperature of
This is selected depending on conditions such as the size of the iron core and changes the size of the inductance L2.

If the temperature of the wound core 11 exceeds the appropriate annealing temperature by /100°C, the voltage of the high frequency AC power supply 16 is adjusted to reduce the temperature of the wound core 11.
The temperature of 400°C is kept constant (held for 11 hours), subtracted by 5. This holding time is suitable for 30 minutes to 2 hours. Since the winding core 1 is continuous, an alternating current is passed through the winding core 14.
1, the direction of the magnetic flux flowing into the central leg of the wound core 11 is reversed, and an induced voltage is generated in the transformer coil 13 wound around this central leg due to the magnetic flux. do not have. In this case, the plate-wound coils 14 are connected in anti-series with each other.

Next, by switching the changeover switch 15, the temporary coil 1/1 is switched and connected from the AC power source 16 side to the DC 11 source 17 side. As a result, the wound core 11 by the temporarily wound coil 14
When the high frequency excitation is removed, the wound core begins to undergo cold 7JI. At the same time, a direct IQ current flows from the DC power supply 17 to the temporary winding coil 14 and forms a wave against the wound core 11.This J is used to cool the wound core 11 in a scalloping vessel. After annealing, the temporarily wound coil 14 is removed from the wound iron core 11 to complete the annealing work.

In the above-mentioned embodiment, in order to excite the wound core at high frequency,
Although a pre-wound coil that is pre-wound around the J and X cores is used, the present invention is not limited to this, and a transformer coil that has five turns on the wound iron core may also be used. However, in this case, there is a problem with the insulation of the transformer coil for high voltage transformers, so it is possible to use it for low voltage transformers.

In addition, it is possible to use a temporary winding coil to cool down the wound core and to apply a DC magnetic field to the core. It is also possible to apply a magnetic field.

It is also possible to use a temporary winding coil to cool the winding core and apply a DC magnetic field to the winding core.
Furthermore, it is possible to apply a DC magnetic field to the core from the process of heating the wound core.

The iron core to be annealed is not limited to wound iron cores, but 31-crystal 71-magnetic P
The same effect can be achieved by using a laminated iron core made by laminating 1 alloy plates.

When annealing is performed, a transformer coil is wound around the iron core and J3
Although this is advantageous in manufacturing, it is not necessarily limited to this, and it is possible to annealing the temporary coil only without winding the transformer coil around the iron core.

[Effects of the Invention] As explained above, according to the Puno method of annealing the iron core of the present invention, when the iron core is excited at high frequency, even if the magnetic permeability decreases in the field-dirty culm of the iron core, it is still larger than the inductance L of the iron core. Since a coil having an inductance L2 is provided in the excitation circuit, the change in inductance due to the decrease in the permeability (J) of the iron core is ignored, and a stable and good excitation strip I'1 with respect to the iron core becomes 111 Therefore, the iron core can be annealed efficiently, and the original magnetic properties of the amorphous positive alloy plate are improved by 1!7.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an annealing method for an iron core according to embodiments of the present invention, and FIG. 2 is a υ diagram showing the relationship between the temperature and magnetic permeability of the iron core. 11...Wound core, 12...Amorphous magnetic alloy plate, 1
3...Transformer coil, 1/I...Temporarily wound coil, 1
5... Selector switch, 1G... High frequency AC power supply, 17... DC power supply, 1
8...-rngukunsu coil, 19... Matching device. 1/-...-axis center, /2. -Body-41 Kushineg t, 3
・-0 concubine bhi 2 shipi'' kt4--・I anti-port 4+lz
, /<ri...71/12/7 Densaki, /7
・-Δ≦5 et al. Shidahi. /8-...-Internet Scooter, //...-Saitani h
C2.1 Figure 7: JL4 ('C) Figure 2

Claims (1)

[Claims] A method in which a high-frequency current for excitation is passed through a coil wound around an iron core made of an amorphous magnetic alloy plate to excite the iron core, and the iron core itself is heated and annealed by a loss generated in the iron core due to this excitation. An iron core characterized in that a coil having an inductance larger than the inductance of the iron core is provided in a circuit for high-frequency excitation of the iron core to compensate for a change in inductance of the excitation circuit caused by a decrease in magnetic permeability due to a rise in temperature of the iron core. annealing method.