JP2018125425A - Blanks, core components and stacked iron cores - Google Patents

Abstract

For example, the loss and BF of a large iron core used in a power plant or a substation, and a medium to small iron core for power reception or distribution are reduced. An iron core component of a transformer formed by laminating a plurality of blanks obtained by cutting from grain-oriented electrical steel sheets. In this iron core component, the magnetic flux density B8A (T) in the magnetization direction at the specific position A in the direction perpendicular to the magnetization direction of the iron core and the specific different from the specific position A in the direction perpendicular to the magnetization direction of the iron core. Regarding the magnetic flux density B8B (T) in the magnetization direction at the position B, there are points A and B where B8B> B8A and B8B-B8A is 0.02 (T) or more. [Selection] Figure 4

Description

  The present invention relates to a blank, an iron core component, and a stacked iron core. Specifically, the present invention relates to a low-loss and high-efficiency transformer blank, an iron core component, and a stacked iron core.

In the trend of CO ₂ emission reduction and energy saving, further reduction of transformer loss is required. Developments to reduce the iron loss of grain-oriented electrical steel sheets, which are iron core materials, are energetically advanced against this movement. However, the loss of the transformer cannot be sufficiently reduced only by reducing the iron loss of the grain-oriented electrical steel sheet. For this reason, a reduction in the loss of the entire iron core is also strongly demanded.

  In particular, in large iron cores used in, for example, power plants and substations, the magnetic path length on the inner peripheral side of the iron core and the magnetic path length on the outer peripheral side are greatly different. For this reason, when a large piled iron core is manufactured with a grain-oriented electrical steel sheet having a uniform magnetic flux density in the plate width direction, magnetic flux is inevitably concentrated on the inner peripheral side, and high iron loss due to high magnetic flux density excitation is inevitable. . Of course, the magnetic path lengths on the inner peripheral side and the outer peripheral side are different not only in the above-described large stacked iron cores but also in medium-to-small stacked iron cores for power reception and distribution. For this reason, even in a medium to small-sized iron core, although not as large as a large iron core, an increase in iron loss due to the concentration of magnetic flux on the inner peripheral side is inevitable.

  Inventions for reducing the loss of the entire iron core have been disclosed so far.

  In Patent Document 1, the average value of the deviation angle of [001] from the rolling direction: within 4 ° and the area ratio of secondary recrystallized grains having a maximum length in the direction perpendicular to the rolling of 60 mm or more: 85% or more An invention relating to a heat-resistant electrical steel sheet is disclosed. According to the present invention, the non-uniformity of the magnetic flux density at the crystal grain size level of the grain-oriented electrical steel sheet having a high magnetic flux density (B8 ≧ 1.96T) can be eliminated, and stable and low without performing the magnetic domain refinement process. It is said that iron loss can be obtained.

  In Patent Document 2, the material of the inner peripheral side m and the outer peripheral side n of the wound core or the stacked core is changed, the inner peripheral side permeability μm> the outer peripheral side permeability μn, and the inner peripheral side iron loss Wm < The iron loss Wn on the outer peripheral side, which is a value obtained by dividing the iron loss of the iron core of the transformer by the iron loss in the rolling direction of the directional electrical steel sheet, and the smaller the BF, the more the directional electrical steel sheet becomes the iron core. An invention that improves (means that the degree of deterioration of iron loss when processed) is small is disclosed. According to this invention, the core loss can be reduced by manufacturing the core using a plurality of materials having different magnetic permeability and iron loss.

  Further, in Patent Document 3, the inner peripheral side of the wound iron core is a highly oriented silicon steel plate, the outer peripheral side is a magnetic domain control silicon steel plate, and the inner peripheral side electromagnetic steel plate is 25% of the total thickness of the wound core. Thus, an invention is disclosed in which the iron loss is improved as compared with the iron loss of a wound iron core composed only of a magnetic domain controlled silicon steel sheet. According to the present invention, the core loss can be reduced by manufacturing the wound core using a plurality of materials having different magnetic permeability and iron loss.

JP 2000-26942 A (Patent No. 3390345) JP 2006-185999 A JP 2007-43040 (Patent No. 4959170)

According to the examination results of the present inventors, the inventions disclosed in Patent Documents 1 to 3 cannot reduce the loss and BF of the stacked core. For example, in the invention disclosed in Patent Document 2, the magnetic flux is concentrated on the material portion of the iron core having a low iron loss to reduce the iron loss as a whole of the iron core. However, when the excitation magnetic flux density Bm of the grain-oriented electrical steel sheet is increased, the iron loss W increases rapidly at about W∝Bm ² . For this reason, the iron loss of the iron core becomes lower if the entire iron core is excited uniformly. This phenomenon is particularly prominent in large-sized stacked iron cores.

  As a result of intensive studies to solve the above-mentioned problems, the inventors have a magnetic flux density distribution in which the magnetic flux density B8 in the rolling direction RD varies in the sheet width direction (direction perpendicular to the rolling direction). By cutting out a blank from the magnetic steel sheet and assembling the stacked iron core using this blank, the non-uniformity of the magnetic flux density (permeability) on the inner and outer peripheral sides of the stacked iron core can be remarkably improved. The inventors have found that loss can be greatly reduced, and have further studied to complete the present invention. The present invention is listed below.

(1) A blank for a transformer core obtained by cutting out from a grain-oriented electrical steel sheet,
At the second specific position in the direction perpendicular to the magnetization direction of the iron core and the magnetic flux density B8A (T) in the magnetization direction at point A, which is the first specific position in the direction perpendicular to the magnetization direction of the iron core. Regarding the magnetic flux density B8B (T) in the magnetization direction at a certain point B, B8B> B8A and B8B-B8A is 0.02 (T) or more, preferably 0.03 (T) or more, more preferably 0.04. (T) A blank in which points A and B are equal to or greater than the above.

(2) The minimum value of the length of the blank existing region in the direction parallel to the magnetization direction is LS and the maximum value of the length is LL, and the magnetic flux density in the magnetization direction at each portion is B8S and When B8L
B8L / B8S: The blank according to item 1, which is more than 1.0 and not more than LL / LS.

  (3) The blank according to item 1 or 2, wherein the iron core is a stacked iron core.

  (4) The chemical composition of the grain-oriented electrical steel sheet is mass%, C: 0.005% or less, Si: 2.0 to 4.5%, Mn: 0.02 to 1.00%, S and Se. Total: 0.005% or less, sol. The blank according to any one of items 1 to 3, which is Al: 0.003% or more, N: 0.005% or less, the remaining Fe and impurities.

  (5) A core component of a transformer formed by singly or by stacking a plurality of blanks obtained by cutting from grain-oriented electrical steel sheets, in a direction perpendicular to the magnetization direction of the core of the transformer Magnetic flux density B8A (T) in the magnetization direction at point A which is the first specific position of the coil, and in the longitudinal direction of the coil at point B which is the second specific position in the direction perpendicular to the magnetization direction of the iron core of the transformer With respect to the magnetic flux density B8B (T), B8B> B8A and B8B-B8A is 0.02 (T) or more, preferably 0.03 (T) or more, more preferably 0.04 (T) or more. And iron core component in which point B exists.

  (6) The minimum value of the length of the blank existing region in the direction parallel to the magnetization direction is LS (mm), the maximum value of the length is LL (mm), and the magnetization direction at each portion 6. The core component according to item 5, wherein the magnetic flux density is B8S (T), B8L (T), and B8L / B8S: more than 1.0 (LL / LS) or less.

  (7) The chemical composition of the grain-oriented electrical steel sheet is mass%, C: 0.005% or less, Si: 2.0 to 4.5%, Mn: 0.02 to 1.00%, S and Se. Total: 0.005% or less, sol. The core constituent member according to 5 or 6, wherein Al: 0.003% or more, N: 0.005% or less, remaining Fe and impurities.

  (8) A transformer core formed by combining a plurality of iron core components, wherein at least one of the plurality of iron core components is the iron core component according to any one of 5-7. There is a stacked iron core.

  In the present invention, “blank” is a material of a yoke iron core or a leg iron core of a transformer, and means a steel sheet piece obtained by cutting a directional electromagnetic steel sheet into a substantially square, a substantially hexagon or a polygon.

  In the present invention, the “iron core constituting member” means a member constituting an iron core having a shape of a substantially quadrangular prism, a substantially hexagonal column or a polygonal column, which is a single blank or a plurality of blanks having substantially the same shape. For example, a yoke iron core or a leg iron core is exemplified.

  Further, in the present invention, the “transformer core” means two or more so as to constitute a magnetic closed circuit (four in a normal single-phase transformer core and five in a three-phase three-leg transformer core). 1) iron core constituent members are combined, and a transformer is configured by further combining with members such as coils.

  The iron core constituting member and the iron core according to the present invention are manufactured using a coil of a grain-oriented electrical steel sheet in which the magnetic flux density B8 in the coil longitudinal direction varies in the plate width direction. In this grain-oriented electrical steel sheet, the magnetic flux density B8A (T) in the coil longitudinal direction at point A, which is the first specific position in the plate width direction, and the point B, which is the second specific position in the plate width direction. Regarding the magnetic flux density B8B (T) in the coil longitudinal direction, B8B> B8A and B8B-B8A is 0.02 (T) or more, preferably 0.03 (T) or more, more preferably 0.04 (T) or more. There are at least one A point and B point.

  The points A and B preferably exist alternately at 1 / n of the plate width, where n is a natural number of 1 or more.

  The difference between the maximum value and the minimum value of the magnetic flux density B8A (T) at the plurality of the A points is 0.01T or less, and the maximum value and the minimum value of the magnetic flux density B8B (T) at the plurality of the B points exist. The difference is preferably 0.01 (T) or less.

  It is preferable that the magnetic flux density B8 from the point A to the point B changes substantially linearly.

  For example, this grain-oriented electrical steel sheet has a longitudinal magnetic flux density B8R (T) at one edge in the plate width direction and a longitudinal magnetic flux density B8L (T) at the other edge in the plate width direction. B8L> B8R, and B8L-B8R is 0.02 (T) or more, preferably 0.03 (T) or more, more preferably 0.04 (T) or more. Here, the magnetic flux densities B8R and B8L at the edge portions mean an average value in a range from the outermost end surface in the plate width direction to 100 mm in the plate width direction.

  Ideally, the magnetic flux density between the two edges changes so as to connect B8R (T) and B8L (T) with a straight line. Irregularities of about 01 (T) may be present, and the effect of reducing iron loss in the stacked iron core can be sufficiently obtained.

  At least the magnetic flux density value on the higher side of the magnetic flux density values on both edge portions is equal to or greater than the magnetic flux density value on the whole width average, and the magnetic flux density value on the lower side among the magnetic flux density values on both edge portions is the magnetic flux density value on the full width average The following is preferable.

  The chemical composition of the grain-oriented electrical steel sheet is, in mass%, C: 0.005% or less, Si: 2.0 to 4.5%, Mn: 0.02 to 1.00%, and the sum of S and Se: 0.005% or less, sol. Al: 0.003% or more, N: 0.005% or less, preferably 0.030% or less in total of at least one of Sn, Sb, Bi, Te or Pb, with the balance being Fe and impurities It is.

  This grain-oriented electrical steel sheet may be manufactured by any manufacturing method and is not limited to a specific manufacturing method. For example, it is manufactured by a manufacturing method including the following basic manufacturing steps (i) to (v).

  (I) By mass%, C: 0.1% or less, Si: 2.0 to 4.5%, Mn: 0.04 to 1.00%, S: 0.002 to 0.05%, sol. A hot-rolled steel sheet containing Al: 0.005 to 0.05% and N: 0.001 to 0.020% and having a chemical composition which is Fe and impurities, and soaking at 900 ° C. or higher as necessary. A cold rolling step in which, after performing hot rolled sheet annealing at a temperature, cold rolling is performed at a cold rolling rate of, for example, 80% or more to obtain a cold rolled steel sheet.

  (Ii) A decarburization annealing process in which cold-rolled steel sheet is decarburized and annealed at a soaking temperature of 800 to 850 ° C. to remove processing distortion due to rolling, and primary recrystallization is exhibited to make the crystal grain size about 6 to 25 μm .

  (Iii) A nitriding annealing step for performing annealing to increase the nitrogen concentration in the steel sheet in an ammonia-containing atmosphere on the cold-rolled steel sheet, which is performed as necessary.

(Iv) Applying and drying (baking) an aqueous slurry containing an annealing separator mainly composed of MgO on the surface of the steel sheet after decarburization annealing, winding it on a coil, and then finishing annealing at 1150 ° C. or higher for a long time. To develop secondary recrystallization, and the Goss orientation grains in which the rolling direction of the steel sheet is the <100> direction and the surface direction of the steel sheet is the {110} direction are about 1 to 2 cm while eroding the surrounding crystal grains. While growing up to the crystal grain size and aligning the crystal orientation, MgO in the annealing separator and SiO ₂ in the internal oxide layer formed on the surface of the cold-rolled steel sheet during decarburization annealing react to produce forsterite (Mg finish annealing step of forming a primary film on the surface of the main component ₂ SiO _4).

This grain-oriented electrical steel sheet is, for example,
(A) The amount of nitriding in the nitriding annealing step is changed in the plate width direction of the cold-rolled steel plate to vary the strength of the inhibitor in the plate width direction, or (b) the gap between the plates of the coil in the finish annealing is changed to the coil The amount of deinhibitor is varied in the plate width direction by changing the plate width direction.

  As a method for changing the nitriding amount of the cold-rolled steel sheet in the sheet width direction, for example, disclosed in Japanese Patent Laid-Open Nos. Hei 3-23224 and Hei 5-1112827 relating to nitriding of the steel sheet is disclosed in Japanese Patent Laid-Open No. 11-21627. This can be easily realized by combining the disclosed contents related to the width direction spraying flow rate changing device. For example, in the nitriding annealing step, a method of changing the spray flow rate of the ammonia-containing atmosphere in the plate width direction, a method of changing the ammonia-containing concentration in the ammonia-containing atmosphere in the plate width direction, or the like can be applied. The ammonia concentration at this time may be 1 to 2% by volume in the region where the nitriding amount is increased, and 0.1 to 0.9% by volume in the region where the nitriding amount is reduced.

  As a method of changing the gap between the coil plates in the finish annealing in the plate width direction, the MgO annealing separator having different particle sizes is applied separately in the plate width direction, and the porosity after drying is changed in the coil width direction, A method of changing the porosity in the plate width direction by applying partially coarse MgO in the plate width direction of the coil by electrostatic coating is applicable. The particle size of MgO at this time may be 5 to 20 μm in the region where the porosity is increased, and 0.1 to 4 μm in the region where the porosity is decreased.

  According to the present invention, it is possible to reduce the loss and BF of a large stacked iron core used in, for example, a power plant and a substation, and a medium to small stacked core for power reception and distribution.

FIG. 1 is a graph showing an example of changes in the position in the plate width direction of the magnetic flux density B8 (distribution of the magnetic flux density B8 in the plate width direction) in the present invention. FIG. 2 is a graph showing an example of a situation where points A and B are alternately present at 1 / n of the plate width. FIG. 3 shows an example in which the difference between the maximum value and the minimum value of the magnetic flux density B8A at a plurality of A points and / or the magnetic flux density B8B (T) at a plurality of B points is 0.01 (T) or less. It is a graph to show. FIG. 4 is a graph showing an example in which the change in magnetic flux density B8 in the region from point A to point B is substantially linear. Fig.5 (a) is a top view which shows the iron core structural member and stacked iron core for single phase transformers, and FIG.5 (b) is a perspective view which shows the iron core structural member and stacked iron core for single phase transformers. FIG. 6A is a plan view showing an iron core component and a stacked iron core of a three-phase three-leg transformer, and FIG. 6B is a perspective view showing an iron core component and a stacked iron core of a three-phase three-leg transformer. FIG. FIG. 7A is a plan view schematically showing an inner iron type stacked iron core for a single-phase transformer, and FIG. 7B schematically shows an inner iron type stacked iron core of a three-phase transformer. FIG. Moreover, FIG.7 (c) is a top view which shows typically the outer iron type | mold iron core for single phase transformers, and FIG.7 (d) is a schematic diagram of the outer iron type iron core of a three phase transformer. FIG.

  A blank, an iron core constituent member and an iron core according to the present invention, a grain-oriented electrical steel sheet which is a raw material thereof, and a method for manufacturing the same will be described. In the following description, “%” regarding chemical composition means “% by mass” unless otherwise specified. In addition, since the blank according to the present invention is obtained by cutting into a predetermined shape from the grain-oriented electrical steel sheet used in the present invention, the blank according to the present invention and the grain-oriented electrical steel sheet will be described together.

1. Blanks and grain-oriented electrical steel sheets according to the present invention (1) Chemical composition of base steel sheet The blanks or grain-oriented electrical steel sheets according to the present invention are generally used as blanks or grain-oriented electrical steel sheet base steel sheets. As long as it has a chemical composition, it is not limited to a specific chemical composition. Below, an example of the chemical composition of the base material steel plate of the blank which concerns on this invention, or a grain-oriented electrical steel plate is demonstrated.

(1-1) C: 0.005% or less C is effective in controlling the structure until the completion of the decarburization annealing process in the manufacturing process. However, when the C content exceeds 0.005%, the magnetic properties of the blank or grain-oriented electrical steel sheet deteriorate due to the magnetic aging phenomenon in which iron carbide precipitates during long-time use. Therefore, the C content is preferably 0.005% or less, and more preferably 0.002% or less.

  On the other hand, it is preferable that the C content is low. However, even if the C content is reduced to less than 0.0001%, the effect of suppressing magnetic aging is saturated and only the production cost increases. Therefore, the C content is preferably 0.0001% or more.

(1-2) Si: 2.0 to 4.5%
Si increases the electrical resistance of steel and reduces eddy current loss. If the Si content is less than 2.0%, the steel sheet is not a ferrite single phase and the magnetic properties are significantly deteriorated. Therefore, Si content becomes like this. Preferably it is 2.0% or more, More preferably, it is 2.8% or more, More preferably, it is 3.0% or more.

  On the other hand, when the Si content exceeds 4.5%, the cold workability of the steel decreases. Accordingly, the Si content is preferably 4.5% or less, more preferably 4.2% or less, and even more preferably 4.0% or less.

(1-3) Mn: 0.02 to 1.00%
Mn combines with S and Se described later during the manufacturing process to form MnS and MnSe. These precipitates function as inhibitors (inhibitors of normal grain growth) and develop secondary recrystallization. Mn further improves the hot workability of the steel. On the other hand, Mn increases the electrical resistance of the blank or grain-oriented electrical steel sheet and improves the iron loss characteristics. For this reason, it is preferable that the Mn content is high in order to obtain excellent magnetic properties.

  If the Mn content is less than 0.02%, these effects cannot be obtained sufficiently. Therefore, the Mn content is preferably 0.02% or more, more preferably 0.05% or more, and further preferably 0.07% or more.

  On the other hand, if the Mn content exceeds 1.00%, the ferrite phase becomes unstable, and the magnetic properties deteriorate. Therefore, the Mn content is preferably 1.00% or less, more preferably 0.40% or less, and still more preferably 0.20% or less.

(1-4) Total of S and Se: 0.005% or less S and Se combine with Mn to form MnS and MnSe that function as inhibitors in the manufacturing process. However, when the S or Se content of the blank or grain-oriented electrical steel sheet exceeds 0.005% in total, the remaining precipitates decrease the magnetic properties, and segregation of S and Se results in blank or grain-oriented electromagnetic steel. Surface defects may occur in the steel sheet. Therefore, the total content of S and Se is preferably 0.005% or less.

  The total content of S and Se in the blank or grain-oriented electrical steel sheet is preferably as low as possible. However, even if the total content of S and Se in the blank or grain-oriented electrical steel sheet is reduced to less than 0.0001%, only the manufacturing cost increases. Therefore, the total content of S and Se in the blank or grain-oriented electrical steel sheet is preferably 0.0001% or more.

(1-5) sol. Al: 0.003% or more Al combines with N in the manufacturing process of grain-oriented electrical steel sheet to form AlN and functions as an inhibitor. On the other hand, sol. Al increases the electrical resistance of the grain-oriented electrical steel sheet and improves the iron loss characteristics. For this reason, sol. A higher Al content is preferred for magnetic properties. sol. If the Al content is less than 0.003%, this effect is small, and the magnetic properties are degraded. Therefore, sol. The Al content is preferably 0.003% or more, more preferably 0.005% or more, and further preferably 0.02% or more. In this specification, sol. Al means acid-soluble Al.

(1-6) N: 0.005% or less N binds to Al in the manufacturing process to form AlN and functions as an inhibitor. However, if the N content of the grain-oriented electrical steel sheet after finish annealing exceeds 0.005%, precipitates remain on the blank or grain-oriented electrical steel sheet, and the magnetic properties are deteriorated. Therefore, the N content is preferably 0.005% or less, more preferably 0.003% or less, and further preferably 0.001% or less. A lower N content is preferred.

  However, reducing the N content to less than 0.0001% only increases the manufacturing cost. Therefore, the N content is preferably 0.0001% or more.

(1-7) Remainder: Fe and impurities The remainder of the chemical composition of the blank or the base steel sheet of the grain-oriented electrical steel sheet is Fe and impurities. Here, impurities are impurities that are mixed from ore, scrap, or production environment as raw materials when industrially producing a base steel sheet, and are not removed from the steel during final annealing (not purified). The following elements remain in steel. Impurity means an element that is allowed to be contained in a content that does not adversely affect the action of the blank or grain-oriented electrical steel sheet.

  The impurities of the blank or the base steel sheet of the grain-oriented electrical steel sheet are one or more of Sn, Sb, Bi, Te or Pb, and the total content of these elements is preferably 0.030% or less.

  All of these elements increase the magnetic flux density of the blank or grain-oriented electrical steel sheet, but are all impurities because they are removed from the base steel sheet by finish annealing. For this reason, as described above, the content of these elements is preferably 0.030% or less in total.

(2) Magnetic flux density distribution The magnetic flux density B8 in the rolling direction of the grain-oriented electrical steel sheet varies in the sheet width direction. That is, in the grain-oriented electrical steel sheet, the magnetic flux density B8A (T) in the rolling direction at point A, which is the first specific position in the sheet width direction, and the rolling direction at point B, which is the second specific position in the sheet width direction. B8B> B8A, and B8B-B8A is 0.02 (T) or more, preferably 0.03 (T) or more, more preferably 0.04 (T) or more. There are at least one point and one B point. There is one point A and one point B in the blank.

  FIG. 1 is a graph schematically showing an example of a change in the position in the plate width direction of the magnetic flux density B8 that matches this situation, that is, an example of the distribution of the magnetic flux density B8 in the plate width direction. In the graph of FIG. 1, points A and B are arbitrary positions in the plate width direction of the grain-oriented electrical steel sheet, and the change in magnetic flux density B8 between them is also arbitrary.

  A blank is cut out from the grain-oriented electrical steel sheet so as to adapt to the change in magnetic flux density B8 from point A to point B. For this reason, in the situation where the distribution of the magnetic flux density B8 is illustrated in the graph of FIG. 1, the grain-oriented electrical steel sheet cannot be effectively used in the sheet width direction.

  For this reason, it is preferable that the points A and B exist alternately in the plate width direction at 1 / n of the plate width, where n is a natural number of 1 or more. FIG. 2 is a graph schematically showing an example of a situation in which the points A and B are alternately present at 1 / n of the plate width. In the graph of FIG. 2, assuming that n = 3, the magnetic flux density B8 periodically fluctuates substantially in an N-type with a period of 1/3 of the plate width of the grain-oriented electrical steel sheet.

  A case different from the case of n = 3 shown in the graph of FIG. 2 will be briefly described. In the case of n = 1, the magnetic flux density B8 monotonously increases from point A to point B over the entire width of the grain-oriented electrical steel sheet. When n = 2, the magnetic flux density B8 periodically changes from the A point to the B point in a substantially V-type or an inverted V-type with a period of ½ of the plate width of the grain-oriented electrical steel sheet. Further, when n = 4, the magnetic flux density B8 periodically changes from the A point to the B point in a substantially M-type or a substantially W-type with a period of ½ of the plate width of the grain-oriented electrical steel sheet.

  In a large transformer, the width of the coil of grain-oriented electrical steel sheet may be used as it is as the iron core of the transformer. In such an application, the absolute value of the difference between the magnetic flux density B8A1 at one edge portion in the plate width direction and the magnetic flux density B8B2 at the other edge portion in the plate width direction is 0.02 (T) or more. That is, a mode in which n = 1 is also exemplified.

  Furthermore, as shown in the graph of FIG. 2, when the characteristics change with a period of 1 / n in the plate width direction of the grain-oriented electrical steel sheet, when cutting a blank having a width of 1 / n from one coil, these The characteristics of the blank are preferably substantially uniform. For this reason, in the grain-oriented electrical steel sheet, it is preferable that the difference between the maximum value and the minimum value of the magnetic flux density B8A (T) at each of the plurality of A points is 0.01 (T) or less. The difference between the maximum value and the minimum value of the magnetic flux density B8B (T) is preferably 0.01 (T) or less.

  FIG. 3 is a graph schematically showing an example of this situation. Comparing the graph of FIG. 3 with the graph of FIG. 2, it can be seen that the characteristic difference in the magnetic flux density B8 at each of the plurality of points A and B is large in the graph of FIG. 2, but small in the graph of FIG.

  Furthermore, the distribution of the magnetic flux density B8 in the region other than the points A and B, that is, the distribution of the magnetic flux density B8 in the region from the point A to the point B is not particularly limited. However, even if there is an increase or decrease of about 0.01 (T) normally found in grain-oriented electrical steel sheets manufactured by an industrial manufacturing process, the effect of the present invention is sufficiently exerted.

  However, the change of the magnetic flux density B8 in the region from the point A to the point B is preferably substantially linear from the viewpoint of industrial production management and quality control. FIG. 4 is a graph schematically showing an example of this situation.

(3) Primary coating The grain-oriented electrical steel sheet used in the present invention basically has a primary coating containing forsterite (Mg ₂ SiO ₄ ) as a main component on the surface of the base steel sheet. However, even if it is a grain-oriented electrical steel sheet (glassless material) which does not have a primary film as disclosed by Unexamined-Japanese-Patent No. 8-225900, the effect is not impaired.

2. Production method of grain-oriented electrical steel sheet The grain-oriented electrical steel sheet used in the present invention may be produced by any production method and is not limited to a specific production method. This grain-oriented electrical steel sheet is manufactured, for example, through a cold rolling process, a decarburizing annealing process, a nitriding annealing process, and a finish annealing process that are employed as necessary.

(1) Cold rolling step In mass%, C: 0.1% or less, Si: 2.0 to 4.5%, Mn: 0.04 to 1.00%, S + Se: 0.002 to 0.05 %, Sol. A hot-rolled steel sheet containing Al: 0.005 to 0.05% and N: 0.001 to 0.030% and having a chemical composition which is Fe and impurities as balance, soaking at 900 ° C. or higher as necessary. After performing hot-rolled sheet annealing at a temperature, for example, cold rolling is performed at a cold rolling rate of 80% or more to obtain a cold-rolled steel sheet.

  The chemical composition of the hot rolled steel sheet in the cold rolling process will be described. First, the essential elements are explained.

  When the C content of the hot-rolled steel sheet exceeds 0.1%, the time required for decarburization annealing becomes long, the manufacturing cost increases, and the productivity also decreases. Therefore, the C content of the hot-rolled steel sheet is preferably 0.1% or less, more preferably 0.08% or less, and still more preferably 0.07% or less.

  Si increases the electrical resistance of steel, but if it is excessively contained, cold workability is reduced. When the Si content is 2.0 to 4.5%, the Si content of the grain-oriented electrical steel sheet after the finish annealing step is 2.0 to 4.5%.

  Mn combines with S and Se during the manufacturing process to form precipitates and functions as an inhibitor. Furthermore, Mn increases the hot workability of the steel. If the Mn content of the hot-rolled steel sheet is 0.04 to 1.00%, the Mn content of the grain-oriented electrical steel sheet after finish annealing is 0.02 to 1.00%.

  S and Se combine with Mn in the manufacturing process to form MnS and MnSe. Both MnS and MnSe function as inhibitors necessary for suppressing grain growth during secondary recrystallization.

  When the total content of S and Se is less than 0.002%, it is difficult to obtain the effect of forming MnS and MnSe. Therefore, the total content of S and Se is 0.002% or more, preferably 0.01% or more.

  On the other hand, if the total content of S and Se exceeds 0.05%, secondary recrystallization does not occur in the production process, and the magnetic properties of the steel deteriorate. Therefore, the total content of S and Se is 0.05% or less, preferably 0.03% or less.

  Al combines with N to form AlN during the manufacturing process. AlN functions as an inhibitor. sol. If the Al content is less than 0.005%, the effect of forming AlN by combining with N cannot be obtained. Therefore, the sol. The Al content is 0.005% or more, preferably 0.01% or more, and more preferably 0.02% or more.

  On the other hand, the sol. When the Al content exceeds 0.05%, AlN becomes coarse, AlN becomes difficult to function as an inhibitor, and secondary recrystallization may not occur. Therefore, the sol. The Al content is 0.05% or less, preferably 0.04% or less, and more preferably 0.03% or less.

  N combines with Al during the manufacturing process to form AlN that functions as an inhibitor. If the N content is less than 0.001%, this effect cannot be obtained. Therefore, the N content is 0.001% or more, preferably 0.005% or more, and more preferably 0.007% or more.

  On the other hand, when the N content exceeds 0.020%, all N is not dissolved in the molten steel, and voids may be generated in the grain-oriented electrical steel sheet. Therefore, the N content is 0.020% or less, preferably 0.012% or less, and more preferably 0.010% or less.

  Next, arbitrary elements will be described. The hot-rolled steel sheet may further contain 0.3% or less in total of one or more of Sb, Sn, or Cu as optional elements.

  Sb, Sn, or Cu is an optional element that is contained if necessary, and may not be contained. By containing Sb, Sn or Cu, the effect of increasing the magnetic flux density of the grain-oriented electrical steel sheet can be obtained.

However, if the total content of Sb, Sn, or Cu exceeds 0.3%, it is difficult to form an internal oxide layer during decarburization annealing. For this reason, at the time of final annealing, the formation of the primary coating which proceeds by the reaction of MgO as the annealing separator and SiO _{2 of the} internal oxide layer is delayed, and the adhesion of the formed primary coating is reduced. Therefore, the total content of Sb, Sn or Cu is 0 to 0.3%.

  The total content of Sb, Sn, or Cu is preferably 0.005% or more, and more preferably 0.007% or more. On the other hand, the total content of Sb, Sn or Cu is preferably 0.25% or less, and more preferably 0.2% or less.

  Bi, Te, or Pb is an optional element that is contained as necessary, and may not be contained. By containing Bi, Te or Pb, the magnetic flux density of the grain-oriented electrical steel sheet can be increased.

  However, if the total content of these elements exceeds 0.03%, these elements segregate on the surface during finish annealing. For this reason, the interface between the primary coating and the steel plate is flattened, and the adhesion of the primary coating is reduced.

  Therefore, the total content of one or more of Bi, Te and Pb is 0 to 0.03%. The total content of one or more of Bi, Te and Pb is preferably 0.0005% or more, and more preferably 0.001% or more.

  The balance of the chemical composition of the hot-rolled steel sheet is Fe and impurities. Here, an impurity is a thing mixed from the ore as a raw material, a scrap, or a manufacturing environment, when manufacturing a hot-rolled steel plate industrially. Impurity means an element that is allowed to be contained in a content that does not adversely affect the action of the grain-oriented electrical steel sheet.

  Next, a method for manufacturing a hot-rolled steel sheet will be described.

  The hot-rolled steel sheet having the above chemical composition is manufactured by a well-known method. An example of the manufacturing method of a hot-rolled steel sheet is as follows. A slab having the same chemical composition as the above hot-rolled steel sheet is prepared. The slab is manufactured through a known refining process and casting process.

  Next, the slab is heated. The heating temperature of the slab is, for example, more than 1150 ° C. and not more than 1400 ° C. Hot rolling is performed on the heated slab to produce a hot rolled steel sheet.

  Next, conditions for cold rolling will be described. The prepared hot-rolled steel sheet is cold-rolled to produce a cold-rolled steel sheet as a base steel sheet. Cold rolling may be performed only once or a plurality of times. When performing cold rolling several times, after performing cold rolling, intermediate annealing is performed for the purpose of softening, and then cold rolling is performed. A cold-rolled steel sheet having a product sheet thickness (a sheet thickness as a product) is manufactured by performing cold rolling one or more times.

  Of the cold rolling rates in one or more cold rollings, the single cold rolling rate is preferably 80% or more. Here, the cold rolling rate (%) is defined as follows.

Cold rolling rate (%) = {1− (thickness of cold rolled steel sheet after the last cold rolling) / (thickness of hot rolled steel sheet before starting the first cold rolling)} × 100
The cold rolling rate is preferably 95% or less. Moreover, before performing cold rolling on a hot-rolled steel sheet, the hot-rolled steel sheet may be heat-treated or pickled. The conditions for hot-rolled sheet annealing are preferably 900 ° C. or higher in order to regulate the metal structure of the stretched hot-rolled steel sheet into equiaxed grains by recrystallization and grain growth. Moreover, when using long-time box annealing, about 800 degreeC may be sufficient.

(2) Decarburization annealing step and nitridation annealing step In the decarburization annealing step, decarburization annealing is performed on the cold-rolled steel sheet that has undergone the cold rolling step to develop primary recrystallization, and nitriding annealing is performed as necessary .

The decarburization annealing is performed in a well-known wet atmosphere containing hydrogen and nitrogen. The C concentration of the grain-oriented electrical steel sheet is reduced to 50 ppm or less by decarburization annealing. In the decarburization annealing, primary recrystallization occurs in the steel sheet, and the working strain introduced by cold rolling is released. Further, in the decarburization annealing process, an internal oxide layer mainly composed of SiO ₂ is formed on the surface layer portion of the steel sheet. The annealing temperature in the decarburization annealing is well-known, for example, 750-950 degreeC. The holding time at the annealing temperature is, for example, 1 to 5 minutes.

  The nitridation annealing is performed between the time of heating in the decarburization annealing process and before the finish annealing as necessary. In the nitriding annealing, the cold-rolled steel sheet is annealed to increase the nitrogen concentration in the steel sheet in an ammonia-containing atmosphere.

(3) Finish annealing step An aqueous slurry containing an annealing separator mainly composed of MgO is applied and dried (baked) on the surface of the cold rolled steel sheet. After this cold-rolled steel sheet is wound on a coil, finish annealing is performed to develop secondary recrystallization. Furthermore, MgO in the annealing separator and SiO ₂ in the internal oxide layer formed on the surface of the cold-rolled steel sheet during the decarburization annealing react to form a primary coating mainly composed of forsterite (Mg ₂ SiO ₄ ). Is formed on the surface.

  In the finish annealing step, first, an aqueous slurry containing an annealing separator is applied to the surface of the cold-rolled steel sheet after decarburization annealing, and the aqueous slurry on the surface of the cold-rolled steel sheet is dried. Annealing (finish annealing) is performed on the steel sheet coated and dried with the aqueous slurry. The aqueous slurry is purified by adding water to an annealing separator to be described later and stirring.

  The finish annealing process is performed, for example, under the following conditions. Bake process before finish annealing. First, an aqueous slurry annealing separator is applied to the surface of the steel sheet. The steel plate having the surface coated with the annealing separator is charged and held in a furnace maintained at 400 to 1000 ° C. (baking process). Thereby, the annealing separator applied to the surface of the steel sheet is dried. The holding time is, for example, 10 to 90 seconds.

  After the annealing separator is dried, finish annealing is performed. In the finish annealing, the annealing temperature is set to 1150 to 1250 ° C., and the base steel plate (the steel plate coated with an annealing separator and dried) is soaked. The soaking time is, for example, 15 to 30 hours. The furnace atmosphere in the finish annealing is a well-known atmosphere.

In the grain-oriented electrical steel sheet manufactured by the above manufacturing process, a primary coating containing Mg ₂ SiO ₄ as a main component is formed.

  Each element of the chemical composition of the hot-rolled steel sheet is removed from the steel components to some extent by the decarburization annealing process and the finish annealing process. In particular, S, N, etc. that function as inhibitors are largely removed in the final annealing process. Therefore, as compared with the chemical composition of the hot-rolled steel sheet, the element content in the chemical composition of the base steel sheet of the grain-oriented electrical steel sheet is reduced as described above. By performing the manufacturing method using a hot-rolled steel sheet having the above-described chemical composition, a grain-oriented electrical steel sheet including a base steel plate having the chemical composition can be manufactured.

In the above manufacturing method, for example,
(A) changing the nitriding amount in the nitriding annealing step in the plate width direction of the cold-rolled steel plate to vary the strength of the inhibitor in the plate width direction; or (b) changing the gap between the coils of the coil in the finish annealing. It is manufactured by changing the amount of deinhibitor in the plate width direction by changing in the plate width direction.

  As described above, as a method of changing the nitriding amount of the cold rolled steel sheet in the sheet width direction, for example, in the nitriding annealing step, a method of changing the spray flow rate of the ammonia-containing atmosphere in the sheet width direction, or in the ammonia-containing atmosphere Examples include a method of changing the ammonia-containing concentration in the plate width direction.

  As described above, as the method of changing the gap between the coil plates in the finish annealing in the plate width direction, the MgO annealing separator having different particle sizes is applied separately in the plate width direction, and the porosity after drying is set in the coil width direction. A method of changing, a method of changing the porosity in the plate width direction by applying coarse MgO partially in the plate width direction of the coil by electrostatic coating, and the like are applicable.

3. Iron Core Components and Stacked Iron Cores According to the Present Invention (1) Iron Core Components 2 and 3 for Single Phase Transformer and Stacked Iron Core 1
FIG. 5A is a plan view showing the iron core components 2 and 3 and the stacked iron core 1 for a single-phase transformer, and FIG. 5B shows the iron core components 2 and 3 and the stacked iron core for a single-phase transformer. 1 is a perspective view showing 1. FIG. 5 (a) and 5 (b), reference numeral 1 is an iron core, reference numeral 2 is a leg iron core, reference numeral 3 is a yoke iron core, and reference numeral 4 is an L-shape of the leg iron core 2 and the yoke iron core 3. A corner portion intersecting the mold, 5 is a straight side portion, 8 is a magnetic flux, and RD is a rolling direction. FIG. 5B schematically shows the coil 7 wound around the leg iron core 2.

  The above-described grain-oriented electrical steel sheet can be used as a material to constitute the stacked iron core 1 according to the present invention for a single-phase transformer. As shown in FIGS. 5 (a) and 5 (b), this stacked iron core 1 includes iron core components 2 and 3 formed by laminating blanks cut from directional electromagnetic steel sheets alone or by laminating a plurality of blanks. A plurality of iron core components 2 and 3 are assembled and assembled. In the stacked iron core 1 shown in FIGS. 5A and 5B, a total of four iron core components 2 and 3 including two yoke iron cores 3 and two leg iron cores 2 are used.

  It suffices that at least one of the plurality of core constituent members 2 and 3 is an iron core constituent member made of the above-described grain-oriented electrical steel sheet. Needless to say, it is preferable that all the iron core constituent members 2 and 3 are iron core constituent members made of the above-described grain-oriented electrical steel sheets.

  In order to obtain good magnetization characteristics, the blanks of the yoke iron core 3 and the leg iron core 2 are parallel to the rolling direction (RD) of the grain-oriented electrical steel sheet in which the magnetization directions of the yoke iron core 3 and the leg iron core 2 are the raw materials. In this way, it is cut from the grain-oriented electrical steel sheet.

  Furthermore, the point A side where the magnetic flux density in the blank is low is arranged on the inner peripheral side of the iron core with low magnetic resistance, and the point B side where the magnetic flux density in the blank is high is arranged on the outer peripheral side of the iron core with high magnetic resistance.

  Here, “magnetic resistance” is approximately (magnetic path length) / (permeability) with respect to magnetic permeability (magnetic flux density / magnetic field) and magnetic path length (path length of magnetic flux in the iron core). By arranging the electromagnetic steel sheets as described above, the magnetic flux flow is made uniform in the core width direction.

  In the iron core constituting members 2 and 3, the magnetic flux density B8A (T) in the magnetization direction at the point A which is the first specific position in the direction perpendicular to the magnetization direction of the iron core 1 (the direction indicated by the double arrow in FIG. 5B). And the magnetic flux density B8B (T) in the magnetization direction at point B which is the second specific position in the direction perpendicular to the magnetization direction of the iron core is B8B> B8A and B8B-B8A is 0.02 (T) or more, The relationship is preferably 0.03 (T) or more, more preferably 0.04 (T) or more.

  In these iron core constituent members 2 and 3, the minimum value of the length of the blank existing region in the direction parallel to the magnetization direction is LS, the maximum value of this length is LL, and the magnetic flux density in the magnetization direction at each portion. Is B8S / B8L, it is preferably B8L / B8S: more than 1.0 LL / LS or less. Thereby, the loss and BF of the stacked iron core 1 can be further reduced.

  That is, in the iron core components 2 and 3 and the iron core 1 using the grain-oriented electrical steel sheet according to the present invention, the magnetization directions of the yoke iron core 3 and the leg core 2 are parallel to the rolling direction (RD) of the grain-oriented electrical steel sheet. The point A having a low magnetic flux density in the grain-oriented electrical steel sheet is disposed on the inner peripheral side of the iron core having a low magnetic resistance, and the point B having a high magnetic flux density is disposed on the outer peripheral side of the core having a high magnetic resistance.

(2) Three-phase three-leg transformer core components 2, 3 and stacked iron core 1-1
FIG. 6A is a plan view showing the iron core components 2 and 3 and the stacked iron core 1-1 of the three-phase three-leg transformer, and FIG. 6B is an iron core component of the three-phase three-leg transformer. It is a perspective view which shows 2 and 3 and the stacked iron core 1-1. 6 (a) and 6 (b), reference numeral 2 is a leg iron core, reference numeral 3 is a yoke iron core, reference numeral 4 is a corner portion where the leg iron core 2 and the yoke iron core 3 intersect in an L shape, reference numeral 4 _T is the corners leg iron core 2 and the yoke iron core 3 intersect in a T-shape, reference numeral 5 is Chokuhen unit, reference numeral 8 denotes a flux, and reference numeral 10 denotes a window portion, RD is the rolling direction It is.

  The above-described grain-oriented electrical steel sheet can be used as a raw material to constitute a stacked iron core 1-1 of a three-phase three-leg transformer. As shown in FIGS. 6 (a) and 6 (b), this stacked iron core 1-1 is formed of a blank obtained by cutting out from a grain-oriented electrical steel sheet alone or by laminating a plurality of blanks. It is formed by combining a plurality of iron core components 2 and 3 including the components 2 and 3. In the example shown in FIG. 6A and FIG. 6B, a total of five core components 2, 3 including two yoke cores 3 and three leg cores 2 are used.

  It suffices that at least one of the plurality of core constituent members 2 and 3 is an iron core constituent member made of the above-described grain-oriented electrical steel sheet. Needless to say, it is preferable that all the iron core constituent members 2 and 3 are iron core constituent members made of the above-described grain-oriented electrical steel sheets.

  In order to obtain good magnetization characteristics, the blanks of the yoke iron core 3 and the leg iron core 2 are respectively arranged so that the magnetization directions of the yoke iron core 3 and the leg iron core 2 are parallel to the rolling direction (RD) of the grain-oriented electrical steel sheet. Plated from grain-oriented electrical steel sheet.

  Furthermore, the point A side where the magnetic flux density is low in the blank is arranged on the low magnetic resistance side, and the point B side where the magnetic flux density is high in the blank is arranged on the high magnetic resistance side, as with the single-phase transformer described above. However, the arrangement shown below can be considered particularly for the center leg.

  One is a case of using a blank in which the A point and the B point exist in a half cycle in the plate width direction. In this case, the point B is arranged on the center side in the width direction of the central leg, and the point A is arranged on both end sides in the width direction of the center leg.

  The other is a case of using a blank in which the points A and B exist in a 1/1 cycle in the plate width direction. In this case, two blanks are arranged so that the point B is located on the center side in the width direction of the center leg and the point A is located on both ends of the center leg.

  In the iron core constituting members 2 and 3, the magnetic flux density B8A (T) in the magnetization direction at the point A which is the first specific position in the direction perpendicular to the magnetization direction of the iron core and the second in the direction perpendicular to the magnetization direction of the iron core. Magnetic flux density B8B (T) in the magnetization direction at point B which is a specific position of B8B> B8A and B8B-B8A is 0.02 (T) or more, preferably 0.03 (T) or more, more preferably Satisfies a relationship of 0.04 (T) or more.

  In these iron core constituent members 2 and 3, the minimum value of the length of the blank existing region in the direction parallel to the magnetization direction is LS, the maximum value of this length is LL, and the magnetic flux density in the magnetization direction at each portion. Is B8S / B8L, it is preferably B8L / B8S: more than 1.0 (LL / LS) or less. Thereby, the loss and BF of the stacked iron core 1-1 can be further reduced.

  In the iron core constituent members 2 and 3 and the iron core 1-1, the side having the lower magnetic flux density among the magnetic flux densities B8R and B8L in the directional electrical steel sheet according to the present invention sheared at the central portion in the plate width direction is the central leg. Or a directional electrical steel sheet having a lower magnetic flux density at both ends than the central magnetic flux density B8, or a sufficiently wide central leg, the magnetic flux density B8R. It is effective to arrange two directional electromagnetic steel sheet coils having different B8L and the lower magnetic flux density at both ends of the central leg.

  As described above, in the present invention, a blank plated from a grain-oriented electrical steel sheet having a magnetic flux density distribution (permeability distribution) in the sheet width direction is used for a part or all of the iron core components, and the inner peripheral side of the stacked iron core For example, large blanks used in power stations and substations, power receiving and distribution, etc. can be obtained by arranging a portion with a low permeability of the blank and a portion with a high permeability of the blank on the outer peripheral side. Consists of medium to small stacked iron cores. Thereby, the nonuniformity of magnetic flux density can be suppressed as a whole iron core, and the iron core loss and BF of a stacked iron core can be reduced.

(3) Shape of iron core constituent member in cross section perpendicular to magnetization direction As described above, the stacked iron core according to the present invention is an iron core obtained by laminating one or a plurality of blanks cut out from the above-mentioned directional electromagnetic steel sheets. Two or more components are formed so as to form a magnetic closed circuit (four in the iron core for a single-phase transformer shown in FIGS. 5A and 5B, FIGS. 6A and 6B). The iron core for a three-phase three-leg transformer shown in b) is composed of a combination of five). The shape of the iron core constituent member in a cross section perpendicular to the magnetization direction of the iron core constituent member will be described.

  In general, as shown in FIGS. 5 (a), 5 (b), 6 (a), and 6 (b), an iron core component member is made of a plurality of blanks having substantially the same plate width. It is formed by laminating in the plate thickness direction. In this case, the shape of the iron core constituent member in a cross section perpendicular to the magnetization direction of the iron core constituent member is a quadrangle.

On the other hand, an iron core of a large transformer may use an iron core component in which the shape of the iron core component in a cross section perpendicular to the magnetization direction of the iron core component is circular. This core component is
(A) When stacking a plurality of blanks in the blank plate thickness direction, adjust the plate width to gradually change so that the shape of the iron core component in the cross section perpendicular to the magnetization direction is circular. Laminating a plurality of cut blanks in the blank plate thickness direction, or (b) After laminating a plurality of blanks having substantially the same plate width in the blank plate thickness direction, it is perpendicular to the magnetization direction by cutting or the like. It is formed by processing the shape in cross section into a circle.

  However, the present invention has the points A and B defined in the present invention in a part of the laminated blanks regardless of whether the cross-sectional shape of the iron core component is a square or a circle. Then, the effect of the present invention can be obtained.

  When the shape of the core constituent member in a cross section perpendicular to the magnetization direction is circular, it is most preferable that all of the plurality of blanks whose plate width gradually changes have the points A and B defined in the present invention. . However, in a blank with a narrow plate width, the fluctuation width of the magnetic flux density due to the position in the plate width direction is small, and it is inevitable that the A point and the B point are not provided. Further, even in an iron core component having a rectangular cross section perpendicular to the magnetization direction, in which blanks having the same shape are laminated, blanks having no A point and B point may be mixed due to a planing relationship.

  For this reason, the core component is preferably formed so that a blank having 30% or more of the number of laminated sheets, more preferably 60% or more of the number of laminated sheets, and more preferably 80% or more of the number of laminated sheets has A point and B point. It is preferable to do.

(4) Outer iron core 11, 11-1
FIG. 7A is a plan view schematically showing an inner iron-type stacked iron core 1 for a single-phase transformer, and FIG. 7B is an inner iron-type stacked iron core 1-1 of a three-phase transformer. It is a top view which shows typically. FIG. 7C is a plan view schematically showing an outer iron type stacked core 11 for a single-phase transformer, and FIG. 7D is an outer iron type stacked iron core 11 of a three-phase transformer. It is a top view which shows -1 typically. 7A to 7D, reference numeral 2 indicates a leg iron core, reference numeral 3 indicates a yoke iron core, and reference numeral 7 indicates a coil wound around the leg iron core 2.

  In the above description, the case where the present invention is applied to the inner iron type stacked core shown in FIGS. 7A and 7B is taken as an example. However, the present invention is not limited to the inner iron-type stacked iron cores 1, 1-1, but the outer iron-type stacked iron cores 11, 11-1 shown in FIGS. The same applies.

  In mass%, C: 0.045%, Si: 3.4%, Mn: 0.09%, S: 0.01%, sol. A steel material containing Al: 0.03%, N: 0.007%, with the remaining Fe and chemical composition as impurities is used as a raw material, and after slab heating at 1200 ° C., hot to a plate thickness of 2.5 mm After rolling and hot-rolled sheet annealing at 1000 ° C., it was cold-rolled to a thickness of 0.30 mm, and nitriding annealing was performed in an ammonia-containing atmosphere when decarburizing annealing was performed at 840 ° C. for 2 minutes.

  At this time, the flow rate of the ammonia-containing atmosphere was changed in the plate width direction, and the nitriding amount of the steel plate was changed in the plate width direction. An annealing separator mainly composed of MgO was applied to the decarburized annealed plate as a water slurry, dried, and then wound into a coil shape at 1200 ° C. for 20 hours.

  Thus, C: 0.002%, Si: 3.4%, Mn: 0.07%, S: 0.001%, sol. Table 1 contains Al: 0.02%, N: 0.001%, the balance is Fe and impurities, and has a plate width of 1000 mm and a distribution of magnetic flux density B8 in the plate width direction. The directional electrical steel sheets S2 and S3 shown were manufactured.

  Further, in the above-described manufacturing process, during the nitridation annealing, the flow rate of the ammonia-containing atmosphere is not changed in the plate width direction, and the nitriding amount of the steel plate is not changed in the plate width direction. A grain-oriented electrical steel sheet S1 of a comparative example shown in Table 1 having no distribution of the magnetic flux density B8 in the width direction was manufactured.

  About the grain-oriented electrical steel sheets S1 to S3 which are these materials, the magnetic flux density B8 over the width direction is measured with a 10 cm-width measurement sample by the above-described method, and 10 points (a ~ J) data was obtained. In Table 1, in addition to the magnetic flux densities B8a and B8j at point a (one end of the plate width) and j point (the other end of the plate width), the magnetic flux density at the center of the plate width, points b to e The average magnetic flux density B8b-e, the average magnetic flux density B8f-i from point f to point i, and the average magnetic flux density B8a-j at 10 points from point a to point j are shown as the characteristics of the entire steel sheet.

  As shown in Table 1, the change in magnetic flux density in the plate width direction of the grain-oriented electrical steel sheet S1 is almost uniform and small. On the other hand, the change in magnetic flux density in the plate width direction of the directional electromagnetic steel plates S2, S3 is large. The magnetic flux density is substantially linear (n = 1) so that the point a side is the point A side of the present invention and the point j of the measurement is the point B side of the present invention. Moreover, the average magnetic flux density in the whole board width is substantially equivalent with the directional electromagnetic steel plates S1-3.

  The blanks A to D shown in Table 2 and FIGS. 5 (a) to 5 (b) cut out from these grain-oriented electrical steel sheets S1 to S3 are arranged on the inner peripheral side of the iron core on the low magnetic flux density side. In addition, the test No. shown in Table 2 is arranged such that the side having a high magnetic flux density is arranged on the outer peripheral side. Single-phase stacked iron core transformers having a capacity of 1 to 100 MVA (upper and lower yoke iron cores: blanks A and B, left and right leg iron cores: blanks C and D) were produced.

  In this embodiment, blanks having the same width are stacked, and the transformer core cross section is rectangular. The transformer size is AB = 3200 mm and DB = 3800 mm. The widths of blanks A, B, C, and D were all 1000 mm, and the steel plates were used as they were.

  In Table 2 and FIGS. 5A to 5B, the short magnetic path side (inner side) of each of the blanks A to D is denoted as A (for example, the inner peripheral side of the blank D is DA), and the long The magnetic path side (outside) is denoted as B. For example, the outer peripheral side of the blank D was described as DB.

  And test no. The iron loss and BF of a single-phase product core transformer having a capacity of 1 to 100 MVA were measured.

  Test No. 2 in Table 2 Nos. 2 to 6 are examples of the present invention that satisfy all the provisions of the present invention. 1 is a conventional example in which the present invention is not carried out. 7 is a comparative example in which the arrangement of blanks C and D does not satisfy the present invention. 8 is a comparative example in which the arrangement of blanks A to D does not satisfy the present invention.

  Test No. 2 uses the grain-oriented electrical steel sheet S2 so that the blanks C and D satisfy the present invention. 3 uses the grain-oriented electrical steel sheet S2 so as to satisfy the present invention for the blanks A, B, C, and D. In No. 4, the grain-oriented electrical steel sheet S3 is used for the blank C so as to satisfy the present invention. In No. 5, the grain-oriented electrical steel sheet S3 is used for the blanks C and D so as to satisfy the present invention. In No. 6, grain oriented electrical steel sheet S3 was used for blanks A, B, C, and D so as to satisfy the present invention. Therefore, excellent values of iron loss: 11.5 to 12.7 kW and BF: 0.94 to 1.03 were obtained.

  In contrast, test no. In Example 1, since the directional electromagnetic steel sheet S1 of the conventional example was used for all of the blanks A, B, C, and D, both the iron loss and BF were inferior values.

  Test No. In No. 7, since the grain oriented electrical steel sheet S2 was used for the blanks C and D so as not to satisfy the present invention, both the iron loss and BF were inferior values.

  Furthermore, test no. In No. 8, since the grain-oriented electrical steel sheet S3 was used for the blanks A, B, C and D so as not to satisfy the present invention, both the iron loss and BF were inferior values.

  Thus, according to this invention, it turns out that the loss and BF of the large-sized stacked iron core used, for example in a power station or a substation, and medium-to-small-sized stacked iron cores for power reception or distribution can be reduced.

  C: 0.07%, Si: 3.1%, Mn: 0.08%, S: 0.03%, sol. A steel material containing Al: 0.025%, N: 0.008% and having a chemical composition as the balance Fe and impurities is used as a raw material, and after slab heating at 1400 ° C., it is hot up to a thickness of 2.2 mm. After rolling and hot-rolled sheet annealing at 1100 ° C., it was cold-rolled to a sheet thickness of 0.27 mm and subjected to decarburization annealing at 850 ° C. for 1 minute.

  When an annealing separator mainly composed of MgO is applied to this decarburized annealed plate as a water slurry, coarse and fine MgO are distributed and applied in the plate width direction, and the porosity between the plates after drying is determined. It was changed in the plate width direction. The steel sheet coil thus obtained was annealed at 1200 ° C. for 20 hours.

  Thus, C: 0.002%, Si: 3.1%, Mn: 0.07%, S: 0.0005%, sol. It contains Al: 0.015%, N: 0.0008%, has a chemical composition that is the balance Fe and impurities, has a plate width of 900 mm, and has a distribution of magnetic flux density B8 in the plate width direction. The grain-oriented electrical steel sheets S5 and S6 shown in Table 3 were produced.

  Further, in the manufacturing process described above, when the annealing separator is applied with a water slurry, the coarse and fine MgO is applied without being distributed in the plate width direction, and the nitriding amount of the steel plate is not changed in the plate width direction. Thus, the grain-oriented electrical steel sheet S4 of the comparative example shown in Table 3 having the chemical composition and having no distribution of the magnetic flux density B8 in the plate width direction was manufactured.

  With respect to the grain-oriented electrical steel sheets S4 to S6 which are these materials, the magnetic flux density B8 across the width direction is measured with a 10 cm-width measurement sample by the above-described method, and nine points from one end to the other end (a Data of i) were obtained. Table 3 shows the magnetic flux density B8a, B8i at point a (one end of the plate width) and point i (the other end of the plate width), as well as the characteristics at the center of the plate width, point b to point d. The average magnetic flux density B8b-d, the magnetic flux density B8e at point e (plate width center), the average magnetic flux density B8f-h at points f to h, and the characteristics of the whole steel sheet are 9 from point a to i. The average magnetic flux density B8a-i of a point is shown.

  As shown in Table 3, the change in magnetic flux density in the plate width direction of the grain-oriented electrical steel sheet S4 is substantially uniform and small. On the other hand, the magnetic flux density change in the plate width direction of the directional electromagnetic steel plates S5, 6 is large. It changes substantially linearly (n = 1) so that the point a side of the grain-oriented electrical steel sheet S5 is the point A side of the present invention and the point i side of the grain-oriented electrical steel sheet S5 is the point B side of the present invention. Further, the magnetic flux density at the center in the plate width direction is high so that the points a and i of the directional electromagnetic steel sheet S6 are the A point side of the present invention and the e point side of the directional electromagnetic steel sheet S6 is the B point side of the present invention. (N = 2) distribution. Moreover, average magnetic flux density B8a-i in the whole board width is substantially equivalent about directional electromagnetic steel plate S4-6.

  The blanks A to E shown in Table 3 and FIGS. 6 (a) to 6 (b) cut out from the grain-oriented electrical steel sheets S4 to S6, which are these materials, have a lower magnetic flux density on the inner peripheral side of the iron core. In addition to the arrangement, the side having the higher magnetic flux density is arranged on the outer peripheral side. 9-15 160 MVA capacity three-phase stacked iron core transformers (upper and lower yoke cores: blanks A and B, left and right leg cores: blanks C and D, central leg iron core: blank E) were produced.

  The blanks A to E shown in Table 2 and FIGS. 6 (a) to 6 (b) cut out from the grain-oriented electrical steel sheets S4 to S6, which are these materials, have a lower magnetic flux density on the inner peripheral side of the iron core. In addition to the arrangement, the side having the higher magnetic flux density is arranged on the outer peripheral side. 9-15 160 MVA capacity three-phase stacked iron core transformers (upper and lower yoke cores: blanks A and B, left and right leg cores: blanks C and D, central leg iron core: blank E) were produced.

  The transformer size is AB = 5800 mm and DB = 3600 mm. The widths of the blanks A, B, C, D, and E are all 900 mm, and the steel plates are used as they are.

  In this embodiment, blanks having the same width are stacked, and the transformer core cross section is rectangular. In Table 4 and FIGS. 6A to 6B, the short magnetic path side (inner side) of each blank A to E is denoted as A (for example, the inner peripheral side of the blank E is set to EA), and the length is long. The magnetic path side (outside) is denoted as B (for example, the outer peripheral side of the blank E is denoted as EB), and the central side is denoted as E. For example, the center side of the blank E was described as EE.

  And test no. The iron loss and BF of a three-phase stacked core transformer having a capacity of 160 to 15 MVA of 9 to 15 were measured.

  Test No. in Table 4 10 to 13, directional electromagnetic steel sheet S5 (characteristic variation n = 1) was used for blanks A to D, and directional electromagnetic S6 (characteristic variation n = 2) was used for blank E. That is, test no. No. 10 uses a grain-oriented electrical steel sheet S5 for the blanks C and D so as to satisfy the present invention. 11 uses a grain-oriented electrical steel sheet S6 for the blank E so as to satisfy the present invention. 12, the directional electrical steel sheet S5 is used for the blanks C and D so as to satisfy the present invention, and the directional electrical steel sheet S6 is used for the blank E so as to satisfy the present invention. In No. 13, directional electrical steel sheets S5 and S6 were used for blanks A, B, C, D and E so as to satisfy the present invention. Therefore, excellent values of iron loss: 28.5 to 29.5 kW and BF: 1.23 to 1.27 were obtained.

  In contrast, test no. In No. 9, since the directional electrical steel sheet S4 of the conventional example was used for blanks A, B, C, D, and E, both the iron loss and BF were inferior values.

  Test No. In No. 14, since the grain-oriented electrical steel sheet S5 was used so that the arrangement of the blanks C and D did not satisfy the present invention, both the iron loss and BF were inferior values.

  Furthermore, test no. In No. 15, since the grain-oriented electrical steel sheet S5 was used for the blanks C and D so as not to satisfy the present invention, both the iron loss and BF were inferior values.

  For this reason, according to this invention, it turns out that the loss and BF of the large iron core used, for example in a power station or a substation, and medium to small iron cores for power reception or distribution can be reduced.

1,1-1 Inner iron type stacked iron core 2 Leg iron core 3 Yoke iron core 4 Corner part 4 where leg iron core and yoke iron core meet in L shape 4 Corner part 5 where _T leg iron core and yoke iron core meet in T shape 8 Magnetic flux 10 Window part 11, 11-1 Iron core type RD Rolling direction

Claims (8)

A blank for a transformer core obtained by cutting out from a grain-oriented electrical steel sheet,
At the second specific position in the direction perpendicular to the magnetization direction of the iron core and the magnetic flux density B8A (T) in the magnetization direction at point A, which is the first specific position in the direction perpendicular to the magnetization direction of the iron core. A blank in which B8B> B8A and B8B-B8A are 0.02 (T) or more and A point and B point exist with respect to magnetic flux density B8B (T) in the magnetization direction at a certain point B. The minimum value of the length of the blank existing region in the direction parallel to the magnetization direction is LS, the maximum value of the length is LL, and the magnetic flux density in the magnetization direction at each portion is B8S and B8L. When
B8L / B8S: The blank of Claim 1 which is more than 1.0 LL / LS or less.   The blank according to claim 1 or 2, wherein the iron core is a stacked iron core.   The chemical composition of the grain-oriented electrical steel sheet is, in mass%, C: 0.005% or less, Si: 2.0-4.5%, Mn: 0.02-1.00%, the sum of S and Se: 0.005% or less, sol. The blank in any one of Claims 1-3 which is Al: 0.003% or more, N: 0.005% or less, remainder Fe and an impurity.   A transformer core component formed of a blank obtained by cutting from a grain-oriented electrical steel sheet alone or by stacking a plurality of blanks, the first in a direction perpendicular to the magnetization direction of the transformer core Magnetic flux density B8A (T) in the magnetization direction at point A which is a specific position of the coil and magnetic flux density B8B in the coil longitudinal direction at point B which is the second specific position in a direction perpendicular to the magnetization direction of the iron core of the transformer An iron core component in which B8B> B8A and B8B-B8A are 0.02 (T) or more with respect to (T). The minimum value of the length of the blank existing region in the direction parallel to the magnetization direction is LS (mm), the maximum value of the length is LL (mm), and the magnetic flux density in the magnetization direction at each portion is When B8S (T), B8L (T),
The core constituent member according to claim 5, wherein B8L / B8S is more than 1.0 (LL / LS) or less.   The chemical composition of the grain-oriented electrical steel sheet is, in mass%, C: 0.005% or less, Si: 2.0-4.5%, Mn: 0.02-1.00%, the sum of S and Se: 0.005% or less, sol. The core component according to claim 5 or 6, wherein Al: 0.003% or more, N: 0.005% or less, the remaining Fe and impurities.   A transformer core formed by combining a plurality of core components, wherein at least one of the plurality of core components is the core component according to any one of claims 5 to 7. Stacked iron core.