JPS634926B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of annealing a wound iron core, and is useful when applied to a method of annealing a wound core while applying a magnetic field.

Conventionally, a wound core formed by winding a material is annealed to remove distortion during winding and processing.
In this case, if a silicon steel plate is used as the material of the wound core, normal annealing is sufficient. However, when a wound core is formed from amorphous electrical steel sheet (hereinafter abbreviated as amorphous), which is a material that has recently appeared, it is necessary to perform annealing while applying a magnetic field. The magnitude of this magnetic field, ie, the strength of the magnetic field, is required to be H=10 oersteds [O _e ].

FIG. 1 shows an example of a conventional method of annealing while applying a magnetic field. As shown in the figure, in this example, wound cores A, B, and C made of amorphous amorphous having different magnetic path lengths are set in an annealing furnace 1, and these wound cores A, B, and C are annealed while being applied with a magnetic field. I do. To apply a magnetic field, the wound cores A, B, and C are provided with excitation coils a, b, and c, respectively, and these excitation coils a, b,
A DC power supply is connected individually to c, and the DC currents I ₁ , I ₂ ,
This is achieved by flowing I ₃ . Note that the magnetic path lengths _la , l _b , and l _c of the wound cores A, B, and C have a relationship of _la < l _b < l _c .

In this way, in this example, a plurality of wound iron cores (only three are shown in FIG. 1) having different magnetic path lengths can be annealed at the same time.

However, this conventional technology has the following drawbacks (i):
(ii) was hot.

(i) To apply a magnetic field of the same strength to each winding core A, B, and C, it is necessary to adjust the magnitude of the DC currents I ₁ , I ₂ , and I ₃ and the number of turns of the excitation coils a, b, and c, which is complicated. It was hot. To explain this in more detail, the magnetic field, ie, the magnetic field H, is generally given by the following equation (1).

H=10/4π×N/l×I...(1) However, N: Number of turns of exciting coil I: DC current l: Magnetic path length of wound core From equation (1) above, it is the same regardless of the difference in the wound core. It is understood that in order to apply a strong magnetic field H, it is necessary to make adjustments such as increasing the number of turns N or increasing the value of the DC current I as the magnetic path length l becomes longer.

(ii) Excitation coil a for each core A, B, and C;
b and c had to be attached, and the installation work was troublesome.

FIG. 2 shows another example of the conventional method. As shown in the figure, in this example, one conductor 2 is passed through the windows of the wound cores A, B, and C, and a magnetic field is applied by passing a direct current I ₀ through the conductor 2. In this way, annealing is performed while applying a magnetic field. Therefore, in this example, the apparatus configuration is simplified, and a plurality of wound cores having different magnetic path lengths can be annealed at the same time.

However, in this prior art, wound cores A, B, and C
Since the magnetic path lengths l _a , l _b , l _c are different, the wound cores A, B,
The strength of the magnetic field applied to C is different, and the wound cores A, B,
There will be a difference in the characteristics of C.

In view of the above-mentioned prior art, it is an object of the present invention to provide an annealing method that can perform annealing while applying a magnetic field of the same intensity to a plurality of wound cores having different magnetic path lengths, and which requires a simple device configuration.

Examples of the present invention will be described below. Note that parts that are the same as those in the prior art are given the same numbers and redundant explanations will be omitted.

FIG. 3 is a circuit diagram for explaining the present invention, and the present invention will be briefly explained based on this diagram. Note that more specific application examples will be described later.

As shown in FIG. 3, in the method of the present invention,
The conductor 3 in the annealing furnace 1 passes through a plurality of wound cores A (only three are shown in the figure), and similarly, the conductor 4 passes through the wound core B, and the conductor 5 passes through the wound core C. ing. These conductors 3, 4, and 5 constitute a parallel circuit, and DC currents I ₀₁ , I ₀₂ , and I ₀₃ which are branched from DC current I ₀ flow through each conductor 3, 4, and 5, respectively. A magnetic field is applied to iron cores A, B, and C. At this time, if the diameters of conductors 3, 4, and ₅ are D ₃ , D ₄ , and D 5, D ₃ ² : D ₄ ² : D ₅ ² = l _a : l _b : l _c ...(2) (However, the conductors are Both are round bars). This was done so that magnetic fields of the same strength are applied to wound cores A, B, and C.
This decision was made based on the findings described below. That is, the relationship between the current I and the magnetic field H is expressed by the following equation (3) from the above equation (1).

I = K ₁ × l × H ... (3) (However, K ₁ = 4π/N × 10) From this formula (3), in order to maintain the magnetic field H at a constant strength, the DC current I and the magnetic path length must be It turns out that l must be proportional. On the other hand, since the DC resistance is inversely proportional to the cross-sectional area of the conductor, the DC current I is proportional to the cross-sectional area. Therefore, the following equation (4) is obtained.

I=K ₂ ×D ² ……(4) (where K ₂ : constant, D: diameter of conductor) From formulas (3) and (4) above, H=K ₃ ×D ² /l ……(5) ( However, K ₃ = K ₂ /K ₁ ). From this equation (5), it can be seen that in order to maintain the magnetic field H at a constant strength, the square of the diameter D ² should be changed in accordance with the change in the magnetic path length l. In other words, if the relationship of equation (2) above is satisfied, the wound core A,
A magnetic field H of the same strength is applied to B and C.

FIG. 4 is a block diagram showing a specific example to which the present invention is applied, and the present invention will be explained in more detail based on this figure. In the figure, 1 is an annealing furnace, 1a is its door, 6 is a heat-resistant brick placed on the floor of the annealing furnace 1, and 7 is an annealing furnace.
is the lower copper plate installed on the heat-reducing brick 6, 3,
4 and 5 are conductors that are electrically connected to the lower copper plate 7 and stand up, and the diameters of the conductors _{3, 4, and 5 are D 3} , D ₄ , and D ₅ .
The relationship is D ₃ < D ₄ < D ₅ . Reference numeral 8 denotes an upper copper plate, which is fixed to the conductors 3, 4, and 5 with bolts 9. Reference numeral 10 denotes a lead conductor, which is connected to the lower copper plate 7 and passes through the annealing furnace 1. A cable 11 is connected to the lead conductor 10 and to a DC power source (not shown). 12
is an outlet conductor, which is connected to the upper copper plate 8 and passes through the door 1a. A cable 13 is detachably connected to the lead conductor 12 and is also connected to the DC power source. Therefore, direct currents I ₀₁ , I ₀₂ , and I ₀₃ flow through the conductors 3, 4, and 5. A, B, and C are wound cores, which are piled up via blocks 14 for each type of wound core. In other words, there are conductors 3 in the stacked multiple wound cores A.
is passed through, and similarly, the conductor 4 is connected to the wound core B.
Further, a conductor 5 passes through the wound core C. By the way, wound core A is 10KVA, B is 30KVA, and C is
It has a capacity of 50KVA. Note that 15 is a heater attached to the wall of the annealing furnace 1.

In this configuration, the diameter D ₃ of the conductor 3 is 10 mm, the diameter D 4 of the conductor 4 is 13 mm, the diameter D ₅ of the conductor ₅ is 15 mm, and the magnetic path length l _a of the wound core A is 600 mm. The magnetic path length l _b of is 1000 mm, and the magnetic path length l _c of wound core C is 1400 mm. Therefore, the magnetic field applied to wound core A is H _a , the magnetic field applied to B is H _b , and the magnetic field applied to C is H _c Then,
From the above formula (5), H _a = K ₃ × 10 ² / 600 = 0.167K ₃ H _b = K ₃ × 13 ² / 1000 = 0.169K ₃ H _c = K ₃ × 15 ^{2 /} 1400 = 0.169K ₃ . From this, it can be seen that magnetic fields of approximately the same strength are applied to the wound cores A, B, and C. Of course, in this embodiment, only one DC power supply is required and no excitation coil is required, so it goes without saying that the device configuration is simple.

In addition, in the example shown in FIG. 4, the case where three types of wound cores A, B, and C are annealed is shown, but if the wound cores to be annealed are set to A and B, the number of wound cores A is increased accordingly. To increase the number of conductors, the conductor 5 may be removed and another conductor having a diameter _D3 , which is the same as the diameter of the conductor 3, may be attached thereto, and the wound core A may be provided on this conductor.

As specifically explained above in conjunction with the embodiments, according to the present invention, a plurality of wound cores having different magnetic path lengths can be annealed at the same time while applying a magnetic field of the same strength, and the apparatus configuration can be simple.

[Brief explanation of the drawing]

Figures 1 and 2 are schematic diagrams for explaining the conventional annealing method, Figure 3 is a circuit diagram for explaining the present invention, and Figure 4 is a configuration diagram showing a specific example to which the present invention is applied. be. In the drawing, 2, 3, 4, 5 are conductors, A, B, C are wound cores, I ₀ , I ₁ , I ₂ , I ₃ , I ₀₁ , I ₀₂ , I ₀₃ are DC currents,
l _a , l _b , and l _c are magnetic path lengths.

Claims (1)

[Claims] 1. In an annealing method in which a conductor is passed through the window of a wound core made of amorphous electrical steel sheet, a direct current is passed through the conductor, and annealing is performed while applying a magnetic field to the wound core.
Among multiple wound cores with different magnetic path lengths, a conductor with a wide cross section is passed through the wound core with a long magnetic path length, and a conductor with a wide cross section is passed through the wound core with a short magnetic path length, and the cross sectional area is narrow corresponding to this magnetic path length. By passing through the conductors connected to each other and connecting both ends of each conductor to the same DC power source to form a parallel circuit with a plurality of conductors, and by passing DC current through each conductor, each winding core with a different magnetic path length is created. A method for annealing a wound iron core, which is characterized by annealing while applying a magnetic field of the same strength to the core.