JPH04306816A - Amorphous core and its annealing method - Google Patents

Abstract

PURPOSE:To provide an annealing method with which embrittlement can be suppressed when an amorphous core is annealed, and also excellent iron loss and excitation capacitance can be obtained. CONSTITUTION:An amorphous iron core is formed using the amorphous material which is excitation-annealed in a nitrogen atmosphere at 300 to 335 deg.C for 120 hours or longer. Accordingly, the embrittlement of the amorphous iron core can be suppressed, and excellent characteristics in iron loss and excitation capacitance can be obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an iron core for a transformer, and more particularly to an iron core using an amorphous material that suppresses the progress of embrittlement, and a method for manufacturing the same, particularly an annealing method.

0002

[Prior Art] A conventional method of annealing Fe, B, and Si-based amorphous iron cores is performed by annealing in a magnetic field at a temperature of 360 to 375°C, as shown in Japanese Patent Application Laid-Open No. 165902/1983. There is.

0003

[Problems to be Solved by the Invention] In the magnetic field annealing method at the above temperature, the amorphous material becomes brittle and easily cracks, and when the coil and core are assembled in the next process, cracks occur in the amorphous material, making it difficult to work. There is a problem that performance and reliability are reduced.

An object of the present invention is to provide an amorphous iron core that suppresses the progress of embrittlement, has excellent workability and reliability, and has improved characteristics in terms of iron loss and excitation capacity.

[0005]

[Means for Solving the Problems] In order to achieve the above object, an amorphous iron core is heated to a temperature of 300 to 300°C in a nitrogen atmosphere.
Annealing is carried out at a temperature of 335° C. for a holding time of 120 minutes or more.

In a preferred embodiment, the amorphous core is excitation annealed with a magnetic field of 600 A/m or more.

0
007]

[Operation] Amorphous iron core is heated to 30℃ in a nitrogen atmosphere.
By annealing at a temperature in the range of 0 to 335°C for a holding time of 120 minutes or more, embrittlement of the iron core can be prevented.

[0008] The amorphous material can be given a predetermined directionality by annealing the amorphous core with a magnetic field of 600 A/m or higher.

[0009]

[Embodiment] An embodiment of the present invention will be described below. As shown in FIG. 5, amorphous materials are laminated in a rectangular shape to form an iron core 1. An electric wire 2 for creating a magnetic field is wound around this for one turn or more, and the wire is placed in an annealing furnace and heated in a nitrogen atmosphere.

FIG. 1 shows the relationship between annealing temperature and iron loss. The iron loss gradually decreases as the annealing temperature rises, reaches a minimum value around about 320° C., and then gradually increases. In practical use, the annealing temperature is higher than 280°C and 380°C.
The iron loss can be reduced to 0.15 W/kg or less up to 0.0°C, and good characteristics can be obtained.

On the other hand, FIG. 2 shows the relationship between annealing temperature and excitation capacity. The excitation capacity decreases as the annealing temperature rises and becomes a nearly constant value from around 320°C to around 380°C.
It increases rapidly from around 380°C. The excitation capacity maintains almost the minimum value when the annealing temperature ranges from 320°C to 380°C, and good characteristics are obtained. Practically, this temperature range is used because the excitation capacity can be reduced to 1 VA/kg or less in the temperature range of 300°C to 380°C.

FIG. 3 shows the relationship between the fracture bending diameter D and the annealing temperature. The fracture bending diameter refers to the diameter at which an amorphous material breaks when it is bent into a U shape and compressed from both sides. This value increases as fragility increases. As the annealing temperature increases, the fracture bending diameter increases almost linearly up to around 270°C, the slope becomes gentle from around 270°C to around 330°C, and when it exceeds around 330°C, the slope increases again, until 350°C. The slope becomes gentle again from around ℃. The amorphous material is divided into a region where it is easy to break (a region where embrittlement has progressed) and a region where it is difficult to break (a region where embrittlement has not progressed) at an annealing temperature of around 330℃.If the temperature is below this temperature, the coil and core can be combined. It is possible to suppress the occurrence of cracks. There is no practical problem with the fracture bending diameter up to about 2 mm, but if it exceeds this value, cracks will occur even in straight sections due to the progression of embrittlement. From this point of view, the actual annealing temperature ranges up to about 335°C.

FIG. 4 shows the relationship between holding time and excitation capacity at an annealing temperature of 320°C. The excitation capacity decreased as the retention time increased, and reached a nearly constant value from around 120 minutes.
Shows good properties. This results in a retention time range of 12
It will be 0 minutes or more.

Based on the above, the amorphous core shown in FIG. Temperature range suitable for annealing, i.e.
A range from 300°C to 335°C will be obtained.

Next, the actual annealing method will be described. The amorphous iron core 1 is placed in an annealing device, the inside of the annealing device is made into a nitrogen atmosphere, the temperature of the core is raised to 320° C., and the core temperature is maintained at 320° C. for 150 minutes. In this case, the temperature is 3
If the temperature is in the range of 00℃ to 335℃, almost the same effects as in the case of 320℃ can be expected in terms of iron loss, excitation capacity, and fracture bending diameter, and if the holding time is 120 minutes or more, the excitation capacity will be almost constant. This is expected to be effective and becomes the practical annealing condition.

[0016] Furthermore, if priority is given to reducing iron loss, the temperature may be set at 280°C to 380°C and the holding time may be set at 120 minutes or more.

After maintaining the iron core temperature at 320° C. for 150 minutes, it is slowly cooled in a nitrogen atmosphere.

[0018] In order to impart magnetic directionality to the amorphous material of the iron core, annealing is performed in a magnetic field, but the generation of this magnetic field is
It is obtained by passing a direct current through the electric wire 2. Actually, Figure 7
As shown in the figure, multiple cores are placed on a pallet and energized at the same time. This magnetic field is generated when the iron core temperature reaches the holding temperature, but the effect is the same even if it is applied after the holding time has ended.

In FIG. 7, a rod-shaped electrode 12 provided to penetrate the iron core 1 forms a one-turn coil. A plurality of electrodes 12 are connected in series as required, and the series-connected sets are further connected in parallel to a DC power source. In FIG. 7, two electrodes 12 are connected in series, and three sets of electrodes 12 are connected in parallel. The DC power source may be a rectified commercial power source.

When magnetic field annealing is started in the middle of slow cooling, the slow cooling time may end before the time required for excitation ends, and the annealing process may take a longer time by the time lag. In order to prevent such a time lag, it is desirable to start when the holding temperature is reached.

Further, if the strength of the magnetic field is 600 A/m or more, the characteristics of iron loss and excitation capacity will be approximately constant values.

[0022] Excitation is carried out until the core reaches a temperature of 150° C. or lower, and the core is taken out of the annealing furnace at a temperature lower than that.

[0023] The iron core obtained in this manner has good properties and the material is not embrittled, so the fracture bending diameter can be reduced to 2 mm or less, and the occurrence of cracks in the amorphous material can be suppressed. Therefore, the work after this step can be facilitated.

[0024]

According to the present invention, it is possible to obtain an amorphous iron core that suppresses the progress of embrittlement, has excellent workability, and has improved properties in terms of iron loss and excitation capacity.

[Brief explanation of the drawing]

FIG. 1 is a characteristic diagram showing the relationship between annealing temperature and iron loss.

FIG. 2 is a characteristic diagram showing the relationship between annealing temperature and excitation capacity.

FIG. 3 is a characteristic diagram showing the relationship between annealing temperature and fracture bending diameter.

FIG. 4 is a characteristic diagram showing the relationship between retention time and excitation capacity.

FIG. 5 is a perspective view showing an annealing state of an amorphous iron core.

FIG. 6 is a characteristic diagram showing a temperature range suitable for annealing.

FIG. 7 is a perspective view showing an amorphous iron core annealing device.

[Explanation of symbols]

1: Amorphous iron core, 2: Excitation wire, 3: DC power supply,
10: Annealing device, 12: Excitation wire

Claims (4)

[Claims] 1. A method for annealing an amorphous iron core, characterized in that the amorphous iron core formed into a predetermined shape is annealed in a nitrogen atmosphere at a temperature of 300 to 335°C for a holding time of 120 minutes or more. Method. 2. The method of annealing an amorphous iron core according to claim 1, wherein the amorphous iron core is annealed by excitation in a magnetic field of 600 A/m or more. 3. An amorphous iron core annealing method, characterized in that the amorphous iron core formed into a predetermined shape is annealed in a nitrogen atmosphere at a temperature of 280 to 380°C for a holding time of 120 minutes or more. Method. Claim 4: Formed into a predetermined shape with a fracture bending diameter of 2
An amorphous iron core characterized in that it is made of an amorphous material annealed in a nitrogen atmosphere so that the thickness is less than mm.