JP6620566B2 - Directional electrical steel sheet, method for manufacturing directionally oriented electrical steel sheet, iron core for transformer or reactor, and noise evaluation method - Google Patents
Directional electrical steel sheet, method for manufacturing directionally oriented electrical steel sheet, iron core for transformer or reactor, and noise evaluation method Download PDFInfo
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Description
本発明は、騒音が小さい変圧器やリアクトルが得られる方向性電磁鋼板およびその製造方法、その電磁鋼板で製造される変圧器やリアクトルの鉄心に関するものである。また、変圧器やリアクトルの鉄心が発する騒音を、鉄心の素材となる方向性電磁鋼板の磁歪特性から評価する騒音評価方法に関するものである。 The present invention relates to a grain-oriented electrical steel sheet from which a transformer and a reactor with low noise can be obtained, a manufacturing method thereof, and a transformer and a reactor core manufactured by the electromagnetic steel sheet. The present invention also relates to a noise evaluation method for evaluating the noise generated by the iron core of a transformer or reactor from the magnetostriction characteristics of a grain-oriented electrical steel sheet that is a material of the iron core.
変圧器は、通電中には常時、騒音を発する。これは、変電所周辺住民の生活環境の劣化を引き起こすため、低い騒音レベルが求められる。騒音問題への対応策として、変圧器発注時の要求仕様で、設置場所に応じた騒音レベルの上限が設定されており、完成した変圧器の騒音レベルがその上限値を超過しないことが強く求められている。 The transformer always emits noise during energization. This causes deterioration of the living environment of the residents around the substation, so a low noise level is required. As countermeasures against noise problems, the upper limit of the noise level according to the installation location is set in the required specifications at the time of ordering the transformer, and it is strongly required that the noise level of the completed transformer does not exceed the upper limit value. It has been.
変圧器の騒音発生源の一つは鉄心で、鉄心騒音の一因は方向性電磁鋼板の磁歪現象である。これは、方向性電磁鋼板が交流で磁化される時、その磁化の強さの変化に伴って電磁鋼板の外形がわずかに変化する現象で、定量的に表現する場合には、一般的に鋼板の長さの変化量ΔＬを元の長さＬで除した歪λとしての値
λ＝ΔＬ／Ｌ
で表される。測定法としては、例えば特許文献１や特許文献２に、磁歪の測定方法や測定装置が提案されている。この磁歪が鉄心に振動を発生させ、それが変圧器のタンクなどの外部構造物に伝搬して騒音となる。
One source of transformer noise is the iron core, and one cause of the iron core noise is the magnetostriction phenomenon of grain-oriented electrical steel sheets. This is a phenomenon in which when the grain-oriented electrical steel sheet is magnetized by alternating current, the outer shape of the electrical steel sheet slightly changes with the change in the strength of the magnetization. A value λ = ΔL / L as a strain λ obtained by dividing the amount of change ΔL in length by the original length L
It is represented by As a measuring method, for example, Patent Literature 1 and Patent Literature 2 propose a magnetostriction measuring method and measuring apparatus. This magnetostriction generates vibration in the iron core, which propagates to an external structure such as a transformer tank and becomes noise.
磁歪特性は、方向性電磁鋼板の構造や状態、具体的には結晶方位集積度や絶縁被膜が鋼板に付与する張力、鋼に内在する歪など、様々な因子によって変化する。従って、磁歪特性が変化すると騒音レベルが変化し、場合によっては騒音の低減が可能である。実際に、非特許文献１には、異なる種類の方向性電磁鋼板を鉄心に用いた２台の変圧器の騒音レベルに差が生じた例が示されている。よって、望ましい磁歪特性を持つ方向性電磁鋼板を使用することが、設定された騒音レベル上限値のクリアにつながると考えられる。 The magnetostrictive characteristics vary depending on various factors such as the structure and state of the grain-oriented electrical steel sheet, specifically the degree of crystal orientation integration, the tension applied to the steel sheet by the insulating coating, and the strain inherent in the steel. Therefore, when the magnetostriction characteristic changes, the noise level changes, and in some cases, noise can be reduced. Actually, Non-Patent Document 1 shows an example in which a difference occurs in the noise level between two transformers using different types of grain-oriented electrical steel sheets as iron cores. Therefore, it is considered that using a grain-oriented electrical steel sheet having desirable magnetostrictive characteristics leads to clearing the set noise level upper limit value.
磁歪特性を変化させる処理の一つとして、方向性電磁鋼板の表面に局部的な歪を導入し、磁区を細分化する技術がある。一般的には、この歪は鋼板圧延方向に対してほぼ直交する方向に線状に導入され、その結果、特許文献３に記載されているように歪導入方向に延伸する還流磁区が形成されて１８０°磁区が細分化され、鉄損を下げる効果を持つ。一方で、磁歪特性を変化させるため、騒音が増大しない歪の導入条件を見出すことが必要である。例えば特許文献４では鋼板表面へのレーザビームの照射による磁区細分化法が取り上げられているが、低鉄損化を図ると共に磁歪も増加させない照射条件が示されている。また特許文献５では同様に電子ビームの照射による磁区細分化法が取り上げられているが、ここでも鉄損と磁歪の双方に良好な結果が得られる照射条件が示されている。 As one of the processes for changing the magnetostriction characteristics, there is a technique for introducing a local strain on the surface of the grain-oriented electrical steel sheet and subdividing the magnetic domains. In general, this strain is linearly introduced in a direction substantially orthogonal to the steel sheet rolling direction, and as a result, a reflux magnetic domain extending in the strain introduction direction is formed as described in Patent Document 3. The 180 ° magnetic domain is subdivided and has the effect of reducing iron loss. On the other hand, in order to change the magnetostriction characteristics, it is necessary to find a condition for introducing a distortion that does not increase noise. For example, Patent Document 4 deals with a magnetic domain refinement method by irradiating the surface of a steel plate with a laser beam, but shows an irradiation condition in which the iron loss is reduced and the magnetostriction is not increased. Similarly, Patent Document 5 deals with the magnetic domain subdivision method by electron beam irradiation, but here also shows irradiation conditions that give good results for both iron loss and magnetostriction.
歪により磁区を細分化した鋼板に関して磁歪の評価を行う場合には、実際の変圧器鉄心の騒音によく相関する評価方法を用いる必要があることは言うまでもない。特許文献４と特許文献５では磁歪のpeak-to-peak値（λｐ−ｐ）を用いて評価しているが、これは磁歪変化の１周期での最大の振れ幅であり、良く用いられる方法である。また、特許文献６では磁歪のzero-to-peak値（λ０−ｐ）を用いて評価しているが、これは磁化０の時点を基準とした最大磁化時点の変位である。
Needless to say, when evaluating magnetostriction for a steel sheet whose magnetic domains are subdivided by strain, it is necessary to use an evaluation method that correlates well with the noise of the actual transformer core. In Patent Document 4 and Patent Document 5, evaluation is made using the magnetostrictive peak-to-peak value (λ p-p ), which is the maximum amplitude in one period of magnetostriction change, and is often used. Is the method. Further, in Patent Document 6, the evaluation is performed using the zero-to-peak value (λ 0-p ) of magnetostriction, and this is the displacement at the maximum magnetization time with reference to the time of
さらに、特許文献７に、騒音レベル予測方法が提案されている。これは、交流励磁時の磁歪変位波形を微分して速度に変換し、それに人の聴覚の周波数特性であるＡ特性聴感補正を適用するもので、磁歪速度レベル（ＬＶＡ）と呼ばれており、より実際の騒音レベルに近い評価が可能であると記載されている。 Furthermore, Patent Document 7 proposes a noise level prediction method. This is to differentiate the magnetostrictive displacement waveform at the time of AC excitation and convert it to velocity, and to apply the A characteristic audibility correction, which is the frequency characteristic of human hearing, and is called the magnetostrictive velocity level (L VA ). It is described that an evaluation closer to the actual noise level is possible.
このように、磁歪評価には様々な方法があるが、これは騒音への対応において絶対的な方法がまだ存在していないことを示す。 As described above, there are various methods for magnetostriction evaluation. This indicates that there is no absolute method for dealing with noise.
また、特許文献４〜６では、レーザや電子ビームの照射法を工夫して磁歪を制御し、騒音抑制に繋げる方法が提案されているが、現在でも鉄心騒音の低減が求められているため、更に工夫された磁区細分化方法が必要である。 Moreover, in patent documents 4-6, although the method of controlling the magnetostriction by devising the irradiation method of a laser or an electron beam and leading to noise suppression is proposed, since reduction of iron core noise is still required, There is a further need for an improved magnetic domain refinement method.
本発明は、少なくとも鋼板表面に鋼板圧延方向と交差して線状に導入された歪によって磁区が細分化された方向性電磁鋼板について、その鋼板を用いて製造された変圧器やリアクトルの鉄心の騒音レベルを低減することを目的とする。さらに、鉄心の騒音レベルを精度良く評価する方法を提供することを目的とする。 The present invention relates to a directional electrical steel sheet whose magnetic domains have been subdivided by strain introduced linearly across the steel sheet rolling direction at least on the steel sheet surface, and the transformer core and reactor core manufactured using the steel sheet. The purpose is to reduce the noise level. Furthermore, it aims at providing the method of evaluating the noise level of an iron core accurately.
上記問題を解決するため、本発明は、少なくとも鋼板表面に鋼板圧延方向と交差して線状に導入された歪によって磁区細分化された方向性電磁鋼板であり、前記歪の導入部に発生した還流磁区について、延伸方向の長さ０．５ｍｍの領域に還流磁区幅が３０μｍ以下の部分が１か所以上含まれ、かつ同領域において還流磁区幅が４０μｍ以上の部分が１か所以上含まれ、鋼板の圧延方向に周波数ｆが５０〜６０Ｈｚの正弦波で変化する最大値が１．７Ｔの磁化を発生させて磁化方向の長さ変化を測定することで得られる磁歪変位波形について、４ｆの周波数の磁歪成分の振幅が０．０３×１０−６以下であることを特徴とする、方向性電磁鋼板を提供する。
In order to solve the above problem, the present invention is a grain-oriented electrical steel sheet that has been subdivided into magnetic domains by strain introduced linearly across the rolling direction of the steel sheet at least on the surface of the steel sheet, and is generated at the strain introduction portion. Regarding the reflux magnetic domain, one or more portions having a reflux magnetic domain width of 30 μm or less are included in a region having a length of 0.5 mm in the extending direction, and one or more portions having a reflux magnetic domain width of 40 μm or more are included in the same region. A magnetostrictive displacement waveform obtained by generating a magnetization having a maximum value of 1.7T and changing the length in the magnetization direction by changing the frequency f with a sine wave having a frequency f of 50 to 60 Hz in the rolling direction of the steel sheet. A grain-oriented electrical steel sheet is provided, wherein the amplitude of the magnetostrictive component of the frequency is 0.03 × 10 −6 or less.
また、歪取り焼鈍として、保定時間８００℃で２時間、降温率１０℃／時間のバッチ焼鈍を行った前記鋼板において、前記磁歪変位波形について、前記歪取り焼鈍前の４ｆの周波数の磁歪成分の振幅λＡ、前記歪取り焼鈍後の４ｆの周波数の磁歪成分の振幅λＢとして、これらが式（１）に示す条件を満足することが好ましい。
０≦λＡ−λＢ≦０．０２×１０−６ ・・・（１）
Moreover, as stress relief annealing for 2 hours at 800 ° C.-holding Ordinary, in the steel sheet was subjected to batch annealing cooling rate 10 ° C. / time, for the magnetostrictive displacement waveform, the magnetostrictive component of the frequency of the stress relief annealing before the 4f amplitude lambda a, as the amplitude lambda B of the magnetostrictive component of frequency 4f after the stress relief annealing, it is preferable that they satisfy the condition of formula (1).
0 ≦ λ A −λ B ≦ 0.02 × 10 −6 (1)
また、本発明は、上記方向性電磁鋼板を製造する方法であって、線状の歪を鋼板表面からのレーザ照射によって導入することを特徴とする、方向性電磁鋼板の製造方法を提供する。前記線状の歪を導入する際に、フォーカスレンズを上下振動させ、その振動をレーザビームのスキャン速度に同期させてもよい。 The present invention also provides a method for producing the grain-oriented electrical steel sheet, characterized in that linear strain is introduced by laser irradiation from the steel sheet surface. When introducing the linear distortion, the focus lens may be vibrated up and down, and the vibration may be synchronized with the scanning speed of the laser beam.
また、本発明は、上記電磁鋼板を用いて製造される変圧器またはリアクトル用の鉄心を提供する。 Moreover, this invention provides the iron core for transformers or reactors manufactured using the said electromagnetic steel plate.
さらに、本発明は、少なくとも鋼板表面に鋼板圧延方向と交差して線状に導入された歪によって磁区細分化された方向性電磁鋼板を用いた鉄心で製造された変圧器またはリアクトルの騒音を評価する方法であり、鉄心素材として使用される前記鋼板の圧延方向に周波数ｆが５０〜６０Ｈｚの正弦波で変化する磁化を発生させて磁化方向の長さ変化を測定することで得られる磁歪変位波形について、４ｆの周波数の磁歪成分の振幅で変圧器またはリアクトルの騒音を評価することを特徴とする、騒音評価方法を提供する。歪取り焼鈍として、保定時間８００℃で２時間、降温率１０℃／時間のバッチ焼鈍を施した、鉄心素材として使用される前記鋼板において、前記歪取り焼鈍を施す前後の４ｆの周波数の成分の磁歪の差によって変圧器またはリアクトルの騒音を評価してもよい。
Furthermore, the present invention evaluates the noise of a transformer or a reactor manufactured with an iron core using a grain-oriented electrical steel sheet that has been subdivided into magnetic domains by strain introduced linearly across the steel sheet rolling direction at least on the steel sheet surface. A magnetostrictive displacement waveform obtained by generating a magnetization that changes with a sine wave having a frequency f of 50 to 60 Hz in the rolling direction of the steel sheet used as the iron core material and measuring the length change in the magnetization direction. A noise evaluation method is provided, characterized in that noise of a transformer or a reactor is evaluated with an amplitude of a magnetostriction component having a frequency of 4f. As stress relief annealing for 2 hours at 800 ° C.-holding scheduled, was subjected to batch annealing cooling rate 10 ° C. / time, Oite the steel sheet used as a core material, the frequency before and after 4f performing the stress relief annealing You may evaluate the noise of a transformer or a reactor by the difference of the magnetostriction of a component.
本発明によれば、電磁鋼板を用いて製造された変圧器やリアクトルの鉄心の騒音レベルを低減させることができる。 ADVANTAGE OF THE INVENTION According to this invention, the noise level of the iron core of the transformer manufactured using the electromagnetic steel plate and a reactor can be reduced.
まず、磁歪の評価方法について述べる。磁歪は一般的には方向性電磁鋼板の原板から採取された一定のサイズの矩形サンプルで測定される。この矩形サンプルの４辺の内、平行な２辺を鋼板の圧延方向に一致させる必要がある。このサンプルに対して、例えば上記特許文献１や特許文献２の方法を用いて磁歪測定する。その時のサンプルの磁化方向は圧延方向に一致させ、磁歪の測定方向もそれに一致させる必要がある。励磁は、５０Ｈｚや６０Ｈｚなどの一定の周波数ｆで一定の振幅の正弦波状の磁化変化が発生する様に制御する必要がある。磁歪評価での正弦波磁化変化の最大値は変圧器鉄心の最大磁化に一致させるのが評価精度面で望ましいが、一致させることが必須ではない。 First, a magnetostriction evaluation method will be described. Magnetostriction is generally measured with a rectangular sample of a certain size taken from an original sheet of grain-oriented electrical steel sheet. Of the four sides of the rectangular sample, two parallel sides need to match the rolling direction of the steel sheet. For this sample, magnetostriction is measured using, for example, the methods of Patent Document 1 and Patent Document 2 described above. The magnetization direction of the sample at that time must match the rolling direction, and the magnetostriction measurement direction must also match. Excitation must be controlled so that a sinusoidal magnetization change having a constant amplitude occurs at a constant frequency f such as 50 Hz or 60 Hz. Although it is desirable in terms of evaluation accuracy that the maximum value of the sine wave magnetization change in magnetostriction evaluation matches the maximum magnetization of the transformer core, it is not essential to match.
磁歪の検出には光学的振動計や歪みゲージなどが使用可能である。注意点は、磁化周波数の４倍の周波数４ｆの磁歪成分が精度良く測定できることである。これは、例えば磁化が５０Ｈｚであれば２００Ｈｚ成分、６０Ｈｚであれば２４０Ｈｚ成分となる。 For detection of magnetostriction, an optical vibrometer or a strain gauge can be used. It should be noted that the magnetostriction component of the frequency 4f, which is four times the magnetization frequency, can be measured with high accuracy. This is, for example, a 200 Hz component if the magnetization is 50 Hz, and a 240 Hz component if the magnetization is 60 Hz.
磁歪λは、鋼板の長さの変化量ΔＬを元の長さＬで除した
λ＝ΔＬ／Ｌ
として表す。サンプルの全長で測定するのであれば、測定された変化量をサンプル長で除し、サンプルの一部分を測定範囲とするのであれば、測定された変化量を測定範囲の長さで除する。
The magnetostriction λ is obtained by dividing the amount of change ΔL in the length of the steel plate by the original length L = λ = ΔL / L
Represent as If the measurement is performed using the entire length of the sample, the measured change amount is divided by the sample length. If a part of the sample is used as the measurement range, the measured change amount is divided by the length of the measurement range.
測定装置には磁歪の変位波形を得る機能が必要である。この変位波形から磁化周波数の４倍の周波数の磁歪周波数成分を抽出する必要があり、そのためには周波数アナライザやＡ／Ｄ変換でデジタル化されたデータを高速フーリエ変換（ＦＦＴ）するソフトウエアなどを用いる。周波数成分の大きさはピーク値、実効値、平均値などいずれで表しても良いが、比較する場合には統一する必要がある。なお、本発明ではピーク値、すなわち０レベルからの最大振幅を用いている。従って、上記式（１）の０．０２×１０−６は実効値では０．０１４×１０−６、平均値では０．０１２×１０−６となる。 The measuring device must have a function of obtaining a magnetostrictive displacement waveform. It is necessary to extract a magnetostriction frequency component having a frequency four times the magnetization frequency from this displacement waveform. For this purpose, a frequency analyzer or software that performs fast Fourier transform (FFT) on data digitized by A / D conversion is required. Use. The magnitude of the frequency component may be expressed by any of peak value, effective value, average value, etc., but it is necessary to unify when comparing. In the present invention, the peak value, that is, the maximum amplitude from the 0 level is used. Therefore, 0.02 × 10 −6 in the above formula (1) is 0.014 × 10 −6 in terms of effective value and 0.012 × 10 −6 in terms of average value.
歪取り焼鈍では、サンプルに内在する転位、欠陥などを除去し、磁区細分化のために導入された歪も含めて全ての歪の解放を行う。このためにはバッチ焼鈍炉や連続焼鈍炉などを用いると良い。ここで注意すべきは歪解放の不足と新たな歪みの導入で、前者は十分な最高温度と時間が、後者にはサンプル内の温度偏差が過剰とならない冷却時の降温率制限が必要である。具体例として、例えばバッチ焼鈍の場合は保定時間８００℃で２時間、降温率１０℃／時間程度である。 In strain relief annealing, dislocations and defects inherent in the sample are removed, and all strains including strains introduced for magnetic domain subdivision are released. For this purpose, a batch annealing furnace or a continuous annealing furnace may be used. What should be noted here is the lack of strain relief and the introduction of new strains, the former requires a sufficient maximum temperature and time, and the latter requires a temperature drop rate limit during cooling that does not cause excessive temperature deviation in the sample. . As a specific example, for example, in the case of batch annealing, the holding time is 800 ° C. for 2 hours, and the temperature drop rate is about 10 ° C./hour.
次に、上記のように４ｆ成分が好ましく制御され、変圧器またはリアクトル用の鉄心素材として使用された際の鉄心騒音が小さくなる鋼板の特徴について説明する。 Next, the characteristics of the steel sheet, in which the 4f component is preferably controlled as described above, and the iron core noise is reduced when used as a core material for a transformer or a reactor, will be described.
本発明の実施形態にかかる方向性電磁鋼板は、少なくとも鋼板表面に鋼板圧延方向と交差して線状に導入された歪によって磁区細分化された方向性電磁鋼板であり、鋼板の圧延方向に周波数ｆの正弦波で変化する最大値が１．７Ｔの磁化を発生させて磁化方向の長さ変化を測定することで得られる磁歪変位波形について、４ｆの周波数の磁歪成分の振幅が０．０３×１０−６以下である。 The grain-oriented electrical steel sheet according to the embodiment of the present invention is a grain-oriented electrical steel sheet that has been subdivided into magnetic domains by strain introduced linearly across the steel sheet rolling direction at least on the steel sheet surface, and has a frequency in the rolling direction of the steel sheet. For a magnetostrictive displacement waveform obtained by generating a magnetization having a maximum value of 1.7 T that changes with a sine wave of f and measuring the length change in the magnetization direction, the amplitude of the magnetostrictive component of the frequency of 4f is 0.03 × 10 −6 or less.
さらに、磁歪変位波形について、歪取り焼鈍前の４ｆの周波数の磁歪成分の振幅λＡ、歪取り焼鈍後の４ｆの周波数の磁歪成分の振幅λＢとして、これらが下記式（１）
０≦λＡ−λＢ≦０．０２×１０−６ ・・・（１）
を満足することが好ましい。
Further, regarding the magnetostrictive displacement waveform, the amplitude λ A of the magnetostrictive component having the frequency of 4f before the strain relief annealing and the amplitude λ B of the magnetostrictive component having the frequency of 4f after the stress relief annealing are expressed by the following formula (1).
0 ≦ λ A −λ B ≦ 0.02 × 10 −6 (1)
Is preferably satisfied.
また、磁歪を制御するために、鋼板表面の還流磁区幅を規定する。すなわち、歪の導入部に発生した還流磁区について、延伸方向の長さ０．５ｍｍの領域に還流磁区幅が３０μｍ以下の部分が１か所以上含まれ、かつ同領域において還流磁区幅が４０μｍ以上の部分が１か所以上含まれることが好ましい。 Further, in order to control magnetostriction, the reflux magnetic domain width on the surface of the steel sheet is defined. That is, with respect to the reflux magnetic domain generated in the strain-introducing portion, one or more portions having a reflux magnetic domain width of 30 μm or less are included in the region having a length of 0.5 mm in the stretching direction, and the reflux magnetic domain width is 40 μm or more in the same region. It is preferable that at least one part is included.
上記のような本発明の実施形態にかかる鋼板は、方向性電磁鋼板表面への歪導入方法の条件を以下のようにして調整することが可能である。 In the steel sheet according to the embodiment of the present invention as described above, the conditions of the strain introduction method to the grain-oriented electrical steel sheet surface can be adjusted as follows.
本発明の実施形態にかかる方向性電磁鋼板の製造方法において、鋼板表面に鋼板圧延方向と交差して線状に導入される歪は、鋼板表面からのレーザ照射によって導入する。また、線状の歪を導入する際には、フォーカスレンズを上下振動させ、その振動とレーザビームのスキャン速度とを同期させることにより制御することが好ましい。 In the method for manufacturing a grain-oriented electrical steel sheet according to an embodiment of the present invention, strain introduced linearly across the steel sheet surface across the rolling direction of the steel sheet is introduced by laser irradiation from the steel sheet surface. Further, when introducing linear distortion, it is preferable to control the focus lens by vibrating it up and down and synchronizing the vibration with the scanning speed of the laser beam.
なお、上記製造方法は、本発明の方向性電磁鋼板の製造法の一例を示すものであり、歪導入方法はレーザ照射に限定されず、フォーカス変動にも限定されるものではない。 In addition, the said manufacturing method shows an example of the manufacturing method of the grain-oriented electrical steel sheet of this invention, and the distortion introduction method is not limited to laser irradiation, It is not limited to focus fluctuation | variation.
次に、実際に鉄心の騒音を確認した結果を以下に示す。局所への歪導入によって磁区細分化された方向性電磁鋼板を複数種類用意して、それぞれの方向性電磁鋼板から、図１に示す３相積鉄心を製作した。これらの鉄心にコイルを巻いて周波数ｆ（５０Ｈｚ）で励磁し、騒音計を用いて騒音レベルを測定した。同時に、鉄心の材料である方向性電磁鋼板から矩形サンプルを作成して歪取り焼鈍を行う前後で、上記特許文献１の方法による磁歪測定を行った。磁歪測定では、まず、従来から用いられているpeak-to-peak値λｐ−ｐ、zero-to-peak値λ０−ｐ、磁歪速度レベルＬＶＡを求めた。更に、本発明の実施形態にかかる、磁歪変位波形から抽出した磁化周波数ｆの４倍すなわち４ｆの周波数の成分の磁歪λＡ、サンプルに歪取り焼鈍を施して同様に求めた磁歪λＢと先のλＡとの差であるλＡ−λＢを求めた。これらの各磁歪評価指標λｐ−ｐ、λ０−ｐ、ＬＶＡ、λＡ、λＡ−λＢと騒音レベルとの間に、どの程度の相関性があるかを、線形近似での相関係数によって検討した。結果を図２〜図６に示す。 Next, the result of actually checking the noise of the iron core is shown below. A plurality of types of grain-oriented electrical steel sheets that were subdivided by introducing strain locally were prepared, and the three-phase core shown in FIG. 1 was manufactured from each grain-oriented electrical steel sheet. Coils were wound around these iron cores and excited at a frequency f (50 Hz), and the noise level was measured using a sound level meter. At the same time, the magnetostriction measurement by the method of Patent Document 1 was performed before and after the rectangular sample was made from the grain-oriented electrical steel sheet, which is the material of the iron core, and the strain relief annealing was performed. In the magnetostriction measurement, first, the peak-to-peak value λ p-p , the zero-to-peak value λ 0-p , and the magnetostriction velocity level L VA that have been conventionally used were obtained. Further, according to the embodiment of the present invention, the magnetostriction λ A of the component of the frequency of 4 times the magnetization frequency f extracted from the magnetostrictive displacement waveform, that is, the frequency of 4f, the magnetostriction λ B similarly obtained by subjecting the sample to the strain relief annealing, which is the difference between the lambda a of sought λ a -λ B. The degree of correlation between each of these magnetostriction evaluation indices λ p-p , λ 0-p , L VA , λ A , λ A -λ B and the noise level is a phase in linear approximation. The number of relationships was examined. The results are shown in FIGS.
まず、図２については、λｐ−ｐと騒音レベルとの相関係数の絶対値｜ｒ｜が０．０１で、相関性は見られない。図３のλ０−ｐについては、｜ｒ｜は０．２１でほとんど相関がない。図４のＬＶＡでは、｜ｒ｜は０．５２で若干の相関が見られるが、十分とは考えられない。本発明の実施形態にかかる図５のλＡは、｜ｒ｜が０．９２で良く相関しており、本発明が効果的であることが示されている。また、本発明の異なる実施形態にかかる図６のλＡ−λＢでは｜ｒ｜が０．９４と、λＡよりもわずかに高い相関性が得られており、本発明の実施形態の内で最も高い相関性が得られている。 First, in FIG. 2, the absolute value | r | of the correlation coefficient between λ p-p and the noise level is 0.01, and no correlation is observed. For λ 0-p in FIG. 3, | r | is 0.21 and has little correlation. In LVA in FIG. 4, | r | is 0.52, and a slight correlation is observed, but it is not considered sufficient. Λ A of FIG. 5 according to the embodiment of the present invention has a good correlation with | r | of 0.92, indicating that the present invention is effective. Further, in λ A -λ B of FIG. 6 according to different embodiments of the present invention, | r | is 0.94, which is a slightly higher correlation than λ A. Of the embodiments of the present invention, The highest correlation is obtained.
本発明の実施形態にかかるλＡが騒音に良く相関するのは、局所への歪導入による磁区細分化が磁歪変位波形の中の磁化変化の４倍の周波数の成分を変化させ、それが鉄心騒音を変化させるためと考えられる。また、歪取り焼鈍を施して測定するλＢを用いてλＡ−λＢを算出すると、磁区細分化のために導入された歪がある状態とない状態との比較になり、その歪の影響がより明確に現れると考えられる。 The reason why λ A according to the embodiment of the present invention correlates well with noise is that magnetic domain subdivision due to local strain introduction changes the frequency component of the magnetization change in the magnetostrictive displacement waveform, which is the iron core. This is considered to change the noise. Further, when λ A -λ B is calculated using λ B measured by performing strain relief annealing, it is compared with a state where there is a strain introduced for domain subdivision and a state where there is no strain, and the influence of the strain Appears to appear more clearly.
低騒音の鉄心の素材となりうる方向性電磁鋼板を得るためには、図５から、λＡが０．０３×１０−６以下であることが好ましい。しかし、この条件では鉄損までは考慮されておらず、低鉄損も確保される条件を見出すことが望ましい。そこで、λＡ−λＢを用いる。まず低騒音を得るためには、図６から、λＡ−λＢが０．０２×１０−６以下であることが好ましい。さらに、鉄損も配慮する。図７は、λＡ−λＢと図１に示す３相積鉄心で測定された鉄損との関係を示す。λＡ−λＢが０以下になると鉄損が急増してしまう。これは磁区細分化が不十分なためと考えられる。つまり、λＡ−λＢを用いることで、鉄心の騒音と鉄損とを両立する観点からの適切な範囲を提示することができる。 In order to obtain a grain-oriented electrical steel sheet that can be a low-noise iron core material, it is preferable from FIG. 5 that λ A is 0.03 × 10 −6 or less. However, even under this condition, iron loss is not taken into consideration, and it is desirable to find a condition that ensures low iron loss. Therefore, λ A −λ B is used. First, in order to obtain low noise, from FIG. 6, it is preferable that λ A −λ B is 0.02 × 10 −6 or less. Also consider iron loss. FIG. 7 shows the relationship between λ A -λ B and the iron loss measured with the three-phase core shown in FIG. When λ A −λ B is 0 or less, the iron loss increases rapidly. This is thought to be due to insufficient domain subdivision. That is, by using λ A -λ B , it is possible to present an appropriate range from the viewpoint of achieving both iron core noise and iron loss.
さらに発明者らはこのような特性が鋼板のどのような特徴によるものかを詳細に検討した。その結果、４ｆ成分の磁歪は、局所への歪導入によって発生する還流磁区の形状に依存することを知見した。具体的には、還流磁区の幅は均一でなく、延伸方向に途切れることなくある程度長く延伸する中において、部分的に幅が狭くなった領域が存在する場合に４ｆ成分の磁歪が好ましい値になることがわかった。その理由は明確ではないが、鋼板が励磁により伸び縮みする際、鋼板中の磁束は均一でなく、特に板厚方向に偏在すること、また還流磁区の延伸方向への１８０°磁壁の移動において還流磁区幅に特定の変動があることが騒音の起因になる鋼板の形状変化において、特に４ｆ成分の周波数帯で有利に働くためと推測される。 Furthermore, the inventors examined in detail what characteristics of the steel sheet have such characteristics. As a result, it has been found that the magnetostriction of the 4f component depends on the shape of the reflux magnetic domain generated by introducing the strain locally. Specifically, the width of the reflux magnetic domain is not uniform, and the magnetostriction of the 4f component becomes a preferable value when there is a region where the width is partially narrowed while stretching to some extent without being interrupted in the stretching direction. I understand. The reason for this is not clear, but when the steel sheet expands and contracts due to excitation, the magnetic flux in the steel sheet is not uniform, and is particularly unevenly distributed in the thickness direction, and it is returned in the movement of the 180 ° domain wall in the extension direction of the return magnetic domain. It is presumed that the specific fluctuation in the magnetic domain width works favorably in the frequency band of the 4f component in the shape change of the steel sheet that causes noise.
以下、実施例および比較例を示して、本発明を具体的に説明する。
（実施例１）
板厚０．２３ｍｍの方向性電磁鋼板でレーザビーム照射条件の異なる５種類の材料を準備した。ここで使用したレーザは、出力パワー２００Ｗ、ビームの板幅方向スキャン速度は２０ｍ／ｓｅｃ、圧延方向照射ピッチは５ｍｍとした。また、フォーカスレンズの振動は２０ｋＨｚとした。それらの材料から、サイズが１００ｍｍ×５００ｍｍのサンプルを採取し、磁束密度１．７Ｔ、周波数５０Ｈｚで磁歪λＡを測定した。具体的には、上記特許文献１に基づき、レーザ振動計の変位出力をデジタルオシロスコープでデジタルデータとし、それをＦＦＴで周波数分析して得た２００Ｈｚの振幅値を磁歪測定長で除した。磁歪測定は歪取り焼鈍前後で行い、磁歪差λＡ−λＢも求めた。
Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.
(Example 1)
Five types of materials with different laser beam irradiation conditions were prepared using a directional electromagnetic steel sheet having a thickness of 0.23 mm. The laser used here had an output power of 200 W, a beam width scan speed of 20 m / sec, and a rolling direction irradiation pitch of 5 mm. The vibration of the focus lens was 20 kHz. A sample having a size of 100 mm × 500 mm was taken from these materials, and the magnetostriction λ A was measured at a magnetic flux density of 1.7 T and a frequency of 50 Hz. Specifically, based on Patent Document 1, the displacement output of the laser vibrometer was converted into digital data with a digital oscilloscope, and the 200 Hz amplitude value obtained by frequency analysis with FFT was divided by the magnetostriction measurement length. The magnetostriction measurement was performed before and after the strain relief annealing, and the magnetostriction difference λ A -λ B was also obtained.
次に、同じ材料を用いて図１の変圧器用３相積鉄心を作製し、励磁コイルを施した。これを無響室内に設置して励磁し、騒音計を用いて騒音レベルを測定した。また、電力計を用いて鉄損を測定した。励磁条件は１．７Ｔ、６０Ｈｚである。これらの結果およびレーザ照射条件と還流磁区幅を表１に示す。 Next, using the same material, the three-phase core for transformer of FIG. 1 was produced and an excitation coil was applied. This was installed in an anechoic chamber and excited, and the noise level was measured using a sound level meter. Moreover, the iron loss was measured using the wattmeter. The excitation conditions are 1.7 T and 60 Hz. Table 1 shows the results, laser irradiation conditions, and reflux magnetic domain width.
材料Ｎｏ．１はフォーカスレンズを上下振動させずにレーザ照射している。還流磁区幅については、全ての材料が最大幅４０μｍ以上で、材料Ｎｏ．３〜５が最小幅３０μｍ以下である。磁歪λＡについては、材料Ｎｏ．１、２、６が本発明の範囲を超えており、本発明例となるのは材料Ｎｏ．３〜５である。ただし、Ｎｏ．５は、磁歪差λＡ−λＢが０未満となっている。 Material No. No. 1 irradiates the laser without vibrating the focus lens. Regarding the reflux magnetic domain width, all the materials had a maximum width of 40 μm or more. 3 to 5 have a minimum width of 30 μm or less. For magnetostriction λ A , material no. 1, 2 and 6 are beyond the scope of the present invention. 3-5. However, no. 5, the magnetostriction difference λ A -λ B is less than 0.
磁歪λＡが０．０３×１０−６以下で、磁歪差λＡ−λＢが０．０２×１０−６以下の材料Ｎｏ．３〜５は、それ以外の材料よりも明らかに低騒音である。ただし、材料Ｎｏ．５は、騒音低減効果はあるものの、磁歪差が負値のため鉄損が他よりも高い。また、磁歪λＡは騒音の大小関係に一致しており、騒音の評価に有効であることがわかる。 Material No. having a magnetostriction λ A of 0.03 × 10 −6 or less and a magnetostriction difference λ A −λ B of 0.02 × 10 −6 or less. 3 to 5 are clearly lower noise than other materials. However, material no. Although 5 has a noise reduction effect, the iron loss is higher than the others because the magnetostriction difference is a negative value. In addition, the magnetostriction λ A agrees with the magnitude relationship of noise, and it can be seen that it is effective for noise evaluation.
なお、本実施例では磁束密度と周波数が磁歪測定と騒音測定で異なるが、評価には問題ないことがわかる。 In this example, the magnetic flux density and frequency differ between magnetostriction measurement and noise measurement, but it is understood that there is no problem in evaluation.
Claims (7)
前記歪の導入部に発生した還流磁区について、延伸方向の長さ０．５ｍｍの領域に還流磁区幅が３０μｍ以下の部分が１か所以上含まれ、かつ同領域において還流磁区幅が４０μｍ以上の部分が１か所以上含まれ、
鋼板の圧延方向に周波数ｆが５０〜６０Ｈｚの正弦波で変化する最大値が１．７Ｔの磁化を発生させて磁化方向の長さ変化を測定することで得られる磁歪変位波形について、４ｆの周波数の磁歪成分の振幅が０．０３×１０−６以下であることを特徴とする、方向性電磁鋼板。 It is a grain-oriented electrical steel sheet that has been subdivided into magnetic domains by strain introduced linearly across the steel sheet rolling direction at least on the steel sheet surface,
Regarding the reflux magnetic domain generated in the introduction portion of the strain, one or more portions having a reflux magnetic domain width of 30 μm or less are included in a region having a length of 0.5 mm in the extending direction, and the reflux magnetic domain width is 40 μm or more in the same region. Contains one or more parts,
Magnetostrictive displacement waveform obtained by generating a magnetization having a maximum value of 1.7 T and changing the length in the magnetization direction by changing the frequency f in a rolling direction of the steel sheet with a sine wave having a frequency f of 50 to 60 Hz. The grain-oriented electrical steel sheet, wherein the magnetostrictive component has an amplitude of 0.03 × 10 −6 or less.
０≦λＡ−λＢ≦０．０２×１０−６ ・・・（１） As stress relief annealing for 2 hours at 800 ° C.-holding Ordinary, in the steel plate subjected to batch annealing cooling rate 10 ° C. / time, for the magnetostrictive displacement waveform, the magnetostrictive component of the frequency of the stress relief annealing before the 4f amplitude λ 2. The grain-oriented electrical steel sheet according to claim 1, wherein A satisfies the condition shown in Formula (1) as an amplitude λ B of a magnetostrictive component having a frequency of 4 f after the strain relief annealing.
0 ≦ λ A −λ B ≦ 0.02 × 10 −6 (1)
線状の歪を鋼板表面からのレーザ照射によって導入することを特徴とする、方向性電磁鋼板の製造方法。 A method for producing the grain-oriented electrical steel sheet according to any one of claims 1 to 2 ,
A method for producing a grain-oriented electrical steel sheet, wherein linear strain is introduced by laser irradiation from the steel sheet surface.
鉄心素材として使用される前記鋼板の圧延方向に周波数ｆが５０〜６０Ｈｚの正弦波で変化する磁化を発生させて磁化方向の長さ変化を測定することで得られる磁歪変位波形について、４ｆの周波数の磁歪成分の振幅で変圧器またはリアクトルの騒音を評価することを特徴とする、騒音評価方法。 It is a method for evaluating the noise of a transformer or a reactor manufactured with an iron core using a directional electrical steel sheet that has been magnetically subdivided by strain introduced linearly across the steel sheet rolling direction at least on the steel sheet surface,
Magnetostrictive displacement waveform obtained by generating a magnetization changing in a rolling direction of the steel sheet used as an iron core material with a sine wave having a frequency f of 50 to 60 Hz and measuring a length change in the magnetization direction. A noise evaluation method characterized by evaluating the noise of a transformer or a reactor with the amplitude of the magnetostriction component of
As stress relief annealing for 2 hours at 800 ° C.-holding scheduled, was subjected to batch annealing cooling rate 10 ° C. / time, Oite the steel sheet used as a core material, the frequency before and after 4f performing the stress relief annealing The noise evaluation method according to claim 6 , wherein noise of the transformer or the reactor is evaluated based on a difference in magnetostriction of components.
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