JP2000294432A - Stacked core type transformer excellent in iron loss characteristics and noise characteristics, and its manufacturing method and manufacturing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain improved iron loss characteristics and noise characteristics by providing two dimensional distortion regions or repeated regions of one dimensional linear distortion at a specific area ratio in T-junction regions of leg electromagnetic steel sheets contiguous with yokes at the T-junction parts. SOLUTION: Distortion regions are provided at both end parts of electromagnetic steel plates constructing an iron core, especially of leg steel sheets 1 contiguous with yokes 2 at the T-junction parts 3. Here, the size of the distortion region is defines in distortion region area %. Namely, it is a value equal to ten times the area of the distortion region divided by the area of the T-junction part 3 region of the steel sheets of the leg part. Two dimensional distortion or repeated linear distortion is provided in the distortion region. Further, as the distortion region area ratio, at least 10% is required. Moreover, the distortion is provided by a roll pressure at both end parts of the leg steel sheets contiguous with the yokes at the T-junction parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stacked iron core transformer mainly used as a power transformer and a method and equipment for manufacturing the same, and more particularly to an improvement in iron loss characteristics and noise characteristics in an actual machine. Things.

[0002]

2. Description of the Related Art Si is contained and the crystal orientation is (110).
Grain-oriented electrical steel sheets oriented in the [001] direction or the (100) [001] direction have excellent soft magnetic properties and are therefore particularly used as iron core materials for power transformers. As a characteristic required for such a _grain- oriented electrical steel sheet, it is generally important that the iron loss value represented by W _17/50 (W / kg), which is a loss when magnetized to 1.7 T at a frequency of 50 Hz, is low. It is. In addition, a high magnetic flux density indicating the superiority of the crystal orientation is required to reduce the exciting current of the transformer. This magnetic flux density is generally represented by a magnetic flux density B ₈ (T) at a magnetizing force of 800 A / m, but a grain-oriented electrical steel sheet having a high magnetic flux density often has a low hysteresis loss and is also excellent in iron loss characteristics. Often.

However, according to recent research, B ₈
It has been found that even when a stacked iron core type transformer is manufactured by using a grain-oriented electrical steel sheet having a high density, good iron loss characteristics of the grain-oriented electrical steel sheet as a material are often not reflected. This means that the material characteristics with good angle cannot be used for the actual characteristics of transformers, and this is a major problem, but at present, no industrially effective solution has been found yet. is there. Normally, the value obtained by dividing the iron loss value of a transformer by the iron loss value of a material measured under the same conditions is used as a DF (Destruction Factor) value or a B value.
It is called F (Building Factor) value. Therefore, it is an urgent need to reduce this value.

[0004] Transformer types with increasing DF values are well known and are three or five legged stacked core type transformers. Further, the cause of the deterioration of the DF value of these transformers is already well understood. In other words, these transformers have an iron core region called a T junction as shown by hatching in FIG. 1. In this region, when the magnetic flux density of the material is high, the flow of the magnetic flux is greatly disrupted. It is known that iron loss of the transformer deteriorates. In the figure, reference numeral 1 denotes a leg of the transformer core, 2 denotes a yoke of the transformer core, and 3 denotes a T junction of the transformer core.

FIG. 2 shows the flow of magnetic flux in this type of transformer. That is, as shown in FIG. 2A, when the magnetic flux flows from the left side of the yoke portion 2 to the leg portion 1 through the T-joint portion 3, the magnetic flux flows in a direction in which the steel sheet is easily magnetized.
Overall good magnetic flux flow is shown. However, FIG.
As shown in (b), in the case where the magnetic flux does not flow toward the leg 1 but flows through the T-junction 3 from the left of the yoke 2 to the right yoke 2 as it is, the original preferred direction In addition to the flow of magnetic flux, it has been observed that the magnetic flux once flows into the iron core of the leg portion 1 and then returns to the yoke portion 2 as shown in the figure. . In this phenomenon, since the magnetic flux density of the steel plate forming the leg 1 is high, the magnetic flux flows toward the iron core of the leg 1, and this causes a material having a high magnetic flux density to deteriorate the actual iron loss of the transformer. Cause.

As a method for solving the above-mentioned problem, there has been proposed a method in which the legs of the iron core of the stacked iron core type transformer are changed to a material having a low magnetic flux density and incorporated.
In addition to complicating the material management, the iron loss characteristic itself of the material is deteriorated, so that the DF value is improved, but the iron loss characteristic itself of the transformer is greatly deteriorated. Therefore, this technique has not been industrially practically used.
In addition, Japanese Patent Publication No. 59-32526 proposes a method of reducing the DF value by increasing the Si content in electrical steel sheets. The upper limit is determined from the aspect of properties, and it is industrially difficult to increase the Si content to such an extent that the effect is recognized by this method, and therefore this method is not practical. Furthermore, Japanese Patent Publication No. Hei 6-63030 discloses that a steel sheet is introduced by dispersing distortions into points (stress points).
Although a technique for reducing the DF has been proposed, in this method, although a decrease in the DF value is recognized, the effect is small, and an effect sufficient to reduce the iron loss value of the entire transformer has been obtained. Absent.

[0007] Separately from this, as regulations on environmental problems have become stricter, in recent years, there has been a need for the development of transformers with low noise, and improvements in this aspect are also desired.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a problem with the above-described stacked iron core type transformer, that is, a transformer using a grain-oriented electrical steel sheet having good iron loss characteristics and a high magnetic flux density as a material. An advantageous method and equipment for manufacturing a stacked iron core transformer that advantageously solves the problem that a desired good iron loss value cannot be obtained when manufactured, that is, the problem that the DF value is degraded and the problem that the noise is loud. The purpose is to propose with.

[0009]

Means for Solving the Problems The inventors of the present invention have been trying to improve the electromagnetic steel sheet by using the conventional technology.
Attention was paid to the T junction of the transformer, which is a problem, and the inventors tried to solve the above problem by devising the electromagnetic steel sheet at this portion. As a result, in the T-joint region of the steel plate which enters from the leg into the T-joint of the transformer as shown by reference numeral 4 in FIG.
One-dimensional (linear) strain or two-dimensional (plane) having a repeating structure over an area of at least 10% or more
It has been found that providing a large strain region is extremely effective in achieving the intended purpose. The present invention
It is based on the above findings.

That is, the gist of the present invention is as follows. 1. An electromagnetic steel sheet constituting the iron core, and a strain area composed of a two-dimensional or linear strain repeated area is provided at both ends of the electromagnetic steel sheet for a leg in contact with the yoke at the T joint at an area ratio.
A stacked iron core transformer excellent in iron loss characteristics and noise characteristics characterized by having 10% or more.

2. An electromagnetic steel sheet constituting an iron core, wherein T
At both ends of the electromagnetic steel sheet for the leg that contacts the yoke at the joint,
A method for manufacturing a stacked iron core type transformer having excellent core loss characteristics and noise characteristics, wherein a strain region formed by repeating a dimensional or linear strain region is provided at an area ratio of 10% or more and then laminated.

3. 2. The method for manufacturing a laminated iron core transformer having excellent core loss characteristics and noise characteristics according to the above item 2, wherein distortion is imparted to the electromagnetic steel sheet for legs by rolling down with a roll.

4. A manufacturing facility for a laminated iron core transformer having excellent iron loss characteristics and noise characteristics, wherein a distortion imparting device is provided after a bevel cutting device in an electromagnetic steel sheet cutting line of a transformer manufacturing equipment.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. First, the transformer of the present invention will be described. The present invention is directed to a stacked iron core type transformer. That is, there are two types of transformers: stacked iron core type and wound iron core type. However, the wound iron core type transformer has no disturbance of the flow of magnetic flux and does not show a significant deterioration of the DF value. did. The number of transformer legs is three or five.
This is a transformer having legs. This is because the T-junction, which is the object of the present invention, does not exist in the two-leg transformer, and the effects of reducing iron loss and noise, which are the objects of the present invention, are not recognized.

In the present invention, the T-joint indicates a core region indicated by hatching in FIG.
The steel plate 2 of the yoke and the steel plate 1 of the leg are joined. As a joining method, there are known methods such as a λ junction and a V junction, all of which are applicable to the present invention.

In the present invention, it is important to provide strained regions at both ends of the electromagnetic steel sheet constituting the iron core, and also the steel sheet for the leg which is in contact with the yoke at the T joint. here,
The size of the strain region is defined as a strain region area ratio (%). That is, a value obtained by dividing the area of the strain imparting area indicated by No. 5 in FIG. 3 by the area of the T-joint area of the steel sheet entering from the leg (for example, the area indicated by No. 4 in FIG. 2C) and multiplying by 100. It is. It is important to apply two-dimensional distortion or repeated linear distortion to the distortion region. That is, as the form of the distortion, one that is two-dimensionally applied to the entire surface of the steel sheet or one that is repeatedly applied linearly is effective. Here, the term “linear” means a name including not only a completely continuous line but also an incomplete line such as a dotted line, a broken line, and a chain line. In the present invention, the term "strain-imparting area" refers to a strain-imparting area when two-dimensional strain is applied, and a maximum area surrounded by a linear-distortion envelope when linear strain is repeatedly applied. Say.

The two-dimensional distortion region or 1
By providing a repetitive area of dimensional linear distortion, it is possible to effectively suppress the flow of magnetic flux in the direction of the legs at the T junction, and as a result, it is possible to reduce iron loss and noise of the transformer. It is achieved together. In this regard,
In the case where the strain is distributed in the form of dots as in the conventional example, the effect of suppressing the flow of magnetic flux from the yoke to the legs due to the strain is extremely small, so that the transformer has a sufficient effect of reducing iron loss and noise. It is probable that it was not obtained.

The area ratio of the strain region must be at least 10%. This is because the area ratio of the strain region is 10
%, The effect of suppressing the flow of magnetic flux from the yoke portion to the leg portion due to strain application is not sufficient, and a sufficiently satisfactory effect of reducing iron loss and noise of the transformer cannot be obtained. . In addition, as conventionally performed, imparting strain to all the steel sheets used for the transformer deteriorates the iron loss of the steel sheets, so that the DF value is improved,
Since the actual iron loss of the transformer deteriorates, it is preferable to limit the strain application region to the T-joint region of the steel sheet that enters the T-joint from the legs, but the iron-loss deterioration does not increase. As long as it is within the range, it may be present in other areas to some extent.

Next, a method for manufacturing a transformer according to the present invention will be described. The manufacturing process of the transformer usually includes lamination of an iron core, an assembling process, processing of a copper wire coil, an assembling process, a joining process thereof, and a process of attaching other components such as a casing. In the present invention, what is particularly important is the structure of the iron core at the time of lamination. That is, the two-dimensional strain region or the one-dimensional linear strain repetition region as described above is provided at both ends of the electromagnetic steel plate forming the iron core and the steel plate for the leg which contacts the yoke at the T joint. That is, 10% or more in area ratio, and then lamination.

One of the effective ways to do this is
There is a method in which strain is imparted to both ends of a steel plate for a leg in contact with a yoke at a T-joint portion by rolling down the roll. More specifically, after the bevel cutting of the steel sheet, a method as shown in FIG. 4 (a) is used to apply distortion to the front and rear ends of the steel sheet. At this time, a flat roll 6 as shown in FIG.
Can be used to apply a two-dimensional distortion, while using a linear projection roll 7 as shown in FIG.
A linear strain can be repeatedly applied.

In addition, as a facility for manufacturing such a transformer,
In the electromagnetic steel sheet cutting line, it is effective to attach a distortion imparting device after the bevel cutting device. Such a strain applying device may be a device using a rolling roll as shown in FIG. 4 (a) or a device using a load press. Furthermore, since the distortion by this device needs to be applied to a specific position of the steel sheet after the bevel cutting, it is preferable to include a device for controlling the position of the steel sheet. Further, the device for imparting such a distortion may be installed at the same position as the bevel cutting in the bevel cutting line, may be installed immediately after, or after. In short, after the bevel cutting, install this device before laminating steel sheets,
What is necessary is just to give distortion.

[0022]

EXAMPLES Example 1 Si: 3.25 wt%, thickness: 0.23 mm, W _17/50 : 0.85
Using a grain-oriented electrical steel sheet having magnetic properties of 0 W / kg, B ₈ : 1.942T, three-phase three-legged, core length: 1000 mm, width: 12
Ten model transformers having a thickness of 200 mm, a thickness of 200 mm, and a width of the yoke and legs of 150 mm were produced. At this time, the joining at the T joint was a V joining method, and the stacking method of the steel sheets was two sheets, each having a five-step step lap. At this time, after the steel plate used as the leg of the T-joint is cut at an oblique angle, the flat roll shown in FIG. 4 (b) is placed on the front and rear end regions of the steel plate as shown in FIG. 3 (a). 6 using the strain applying device shown in FIG.
The strain was applied by applying a pressure of g / cm. Here, as the steel sheet of the above-mentioned leg portion of the grain-oriented electrical steel sheet used for each model transformer, the size of the strain application region was changed, and the strain application region area ratio was 0, 3, 6, 10, 10, 50, respectively. 80, 120, 150, 200
%, And various transformers were manufactured using a steel plate to which a strain of% was applied. The area ratio of 100% or more refers to a case where the steel sheet constituting the leg exceeds the region 4 in which the leg enters the T-joint in FIG.

As a conventional example, a protrusion of 1.2 mm
A stress point was applied to the entire steel plate by using protrusion rolls embedded at intervals of mm, and a transformer having the same specifications was manufactured using the steel plate. Table 1 shows the results obtained by examining the iron loss characteristics, DF values, and noise characteristics of the thus obtained transformer. FIG. 5 shows the relationship between the area ratio of the strain imparting region, the iron loss characteristic, and the DF value.

[0024]

[Table 1]

As is clear from Table 1 and FIG. 5, the iron loss value and the noise value of the transformer manufactured according to the present invention are greatly improved as compared with the conventional example, and the area ratio of the strain imparting region is 10%. % Is required.

Example 2 A steel sheet containing 3.05% by weight and having a large number of grooves for magnetic domain subdivision on one side of the steel sheet: 0.30 mm in thickness, W _17/50 : 0.818 W /
kg, B ₈ : Model transformer with three phases, three legs, iron core length: 1000mm, width: 1200mm, thickness: 200mm, yoke and leg width: 150mm, using grain-oriented electrical steel sheets with magnetic properties of 1.913T. Were created. At this time, the T-joined portion was joined by the λ joining method, and the stacking method of the steel sheets was alternately stacked by two sheets.
Of these, one was cut off at a bevel and then laminated as it was to produce a transformer, which was used as a comparative example. In addition, another one cuts a steel plate used as a leg of a T-joint at an oblique angle, and then, as shown in FIG.
The strain was applied to the front and rear end regions of the steel sheet as shown in FIG. As a method for applying the strain, the linear projection roll 7 shown in FIG. 4C was used, and the strain applying apparatus shown in FIG.
A steel sheet was passed through with a pressure of cm. In addition, the remaining one is
As a conventional example, a stress point was applied to the entire steel sheet using a projection roll in which projections of 1.0 mmφ were embedded at intervals of 4 mm, and a transformer having the same specifications was manufactured using the steel sheet. Table 2 shows the results obtained by examining the iron loss characteristics, the DF value, and the noise characteristics of the transformer thus obtained.

[0027]

[Table 2]

As is apparent from Table 2, the iron loss value and the noise value of the transformer manufactured according to the present invention are greatly improved as compared with the conventional example and the comparative example.

[0029]

Thus, according to the present invention, a two-dimensional distortion region or a one-dimensional linear distortion is formed at an area ratio of 10% or more in the T joint region of the electromagnetic steel sheet for a leg which contacts the yoke at the T joint. By providing the repetition region, the iron loss characteristics and the noise characteristics of the stacked iron core type transformer can be remarkably improved as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a diagram showing a core structure of a three-legged transformer including a yoke and legs and positions of T-joints.

FIG. 2 is a diagram showing the flow of magnetic flux at a T junction;
(a) shows the case where the magnetic flux flows from the yoke to the leg, and (b) shows the case where the magnetic flux flows from the yoke to the yoke without flowing to the leg. FIG. 3 (c) shows a T-joined region of the electromagnetic steel sheet for a leg.

FIG. 3 is a diagram showing a shape of a leg electromagnetic steel sheet and a strain imparting region in the steel sheet.

FIG. 4 (a) is a diagram showing an example of a distortion applying device, and FIG.
FIG. 3 is a diagram showing a shape of a flat roll, and FIG. 3C is a diagram showing a shape of a linear projection roll.

FIG. 5 is a diagram showing the relationship between the area ratio of the strain imparting region and the iron loss value and the DF value of the transformer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Leg of transformer core 2 Yoke part of transformer core 3 T junction of transformer core 4 T junction area 5 Strain application area 6 Flat roll 7 Linear projection roll

Claims (4)

[Claims] 1. An electromagnetic steel sheet constituting a core, wherein at both ends of a magnetic steel sheet for a leg which is in contact with a yoke at a T-joint, a strain region comprising a two-dimensional or linear strain repeated region is provided. A core-type transformer with excellent iron loss characteristics and noise characteristics, characterized by having at least 10% by weight. 2. A magnetic steel sheet constituting an iron core, wherein at both ends of a magnetic steel sheet for a leg which is in contact with a yoke at a T-joint, a strain region comprising a two-dimensional or linear strain repetitive region is provided. A method for manufacturing a core-type transformer excellent in iron loss characteristics and noise characteristics, characterized by laminating after giving 10% or more by the method. 3. The method according to claim 2, wherein strain is imparted to the electromagnetic steel sheet for the leg by rolling down with a roll. 4. A manufacturing facility for a laminated iron core transformer having excellent iron loss characteristics and noise characteristics, wherein a distortion imparting device is provided after a bevel cutting device in an electromagnetic steel sheet cutting line of a transformer manufacturing facility. .