JP4284870B2 - Method for producing non-oriented electrical steel sheet for reluctance motor iron core - Google Patents

Description

【００３４】
【表２】

【００３５】
表２から明らかなように、鉄損Ｗ_15/800(L+C) が 150 W/kg 以下で、かつ残留磁束密度Ｂr_1.8が 1.0Ｔ以下の材料を素材として用いた場合に，とりわけ良好なモータ効率が得られている。
【００３６】
実施例２
表１に示した鋼Ｇ，Ｈ，Ｋ，Ｌを素材として製品板を製造するに際し、表３に示すようにタンデム圧延条件および焼鈍温度を種々に変化させて、冷間圧延および仕上げ焼鈍を行った。
なお、冷間圧延に使用したタンデム圧延機は４スタンドからなり、このうちスタンド入側温度が一番高いものについて、入側温度と圧下率を示した。また、スラブ加熱、熱延板焼鈍およびコーティング処理は実施例１と同じ条件で行った。
かくして得られた製品板から、素材評価のためＬ，Ｃ方向のエプスタイン試験片を採取し、磁気特性を測定した。また、300Wのスイッチトリラクタンスモータを試作して、そのモーター効率を測定した。
得られた結果を表３に併記する。
【００３７】
【表３】

【００３８】
表３に示したとおり、本発明に従えば、高周波・高磁束密度域における鉄損が低く、かつ残留磁束密度が小さい電磁鋼板を得ることができ、ひいてはかかる鋼板を素材として用いることによって、スイッチトリラクタンスモータのモータ効率を格段に向上させることができた。
【００３９】
【発明の効果】
かくして、本発明によれば、高周波・高磁束密度域における鉄損が低く、かつ残留磁束密度が小さい無方向性電磁鋼板を得ることができ、ひいてはかような高周波・高磁束密度域における磁気特性に優れた鋼板を素材として使用することにより、高効率のリラクタンスモータを得ることができる。
【図面の簡単な説明】
【図１】 定格が 300Ｗのスイッチトリラクタンスモータの最大効率に及ぼす素材の鉄損Ｗ_15/800(L+C) と残留磁束密度Ｂr_1.8の影響を示した図である。
【図２】 通常の励磁と片側励磁のヒステリシスループ（Ｂ−Ｈループ）の違いを比較して示した図である。[0001]
[Industrial application fields]
This invention relates to a manufacturing method of a preferred non-oriented electrical steel plate as core material for the switched reluctance motor even during re reluctance motor.
[0002]
[Prior art]
In recent years, with increasing demand for energy saving, the trend toward higher efficiency of electrical equipment has increased. In order to meet the above requirements, steel sheet manufacturers have made efforts to improve the iron loss characteristics of electrical steel sheets for electrical equipment by various means as described below.
[0003]
Now, the addition of Si to the electrical steel sheet is the most effective means for reducing iron loss by increasing the specific resistance of the steel sheet, and this means is widely used in the field of electrical steel sheets. As an additive element, Al is known to have the same effect as Si.
For example, Japanese Patent Application Laid-Open No. 53-66816 proposes the positive addition of Al in order to increase the specific resistance of the steel sheet and avoid the effect of suppressing grain growth due to the precipitation of fine AlN.
In JP-A-55-73819, good high magnetic field characteristics are achieved by adding Al and reducing the internal oxide layer on the steel sheet surface by adjusting the annealing atmosphere.
Furthermore, in JP-A-54-68716 and JP-A-58-25427, by adding Al and adding REM and Sb in combination or purifying, the texture is improved. Iron loss is reduced.
[0004]
In addition, in JP-A-61-87823, Al is added to control the steel sheet cooling rate during finish annealing, and in JP-A-3-274247, Al is added and B, Sb, By preventing oxynitridation by composite addition of Sn, Japanese Patent Application Laid-Open No. 3-294422 discloses that by adding Al and controlling the cold rolling to reduce the L and C characteristic ratio of the steel sheet, -63252 discloses a composite addition of Mn and Al, and Japanese Patent Laid-Open No. 4-136138 discloses an addition of Al, an extremely low Si content, and an improvement of the texture by addition of P and Sb. Both have achieved improved magnetic properties.
[0005]
Recently, in addition to increasing the efficiency of rotating equipment, recyclability has been demanded.
A normal induction motor, DC motor, and brushless DC motor all use a conductor such as aluminum or copper or a magnet for the rotor core. Therefore, in order to recycle the iron core, it is necessary to separate these from the magnetic steel sheet.
On the other hand, since the reluctance motor uses reluctance torque as its driving force, the rotor portion basically does not require a conductor or a magnet, and only a magnetic steel plate is sufficient. Therefore, research has been conducted for a long time because it has features such as high recyclability, simple structure, low cost, and robustness.
[0006]
On the other hand, however, it has been difficult to control the rotation and the noise during the rotation is severe, so that it has not been put into practical use for a long time.
In this regard, recent advances in semiconductor technology and control technology have solved these problems, and practical application has been promoted as motors for washing machines and vacuum cleaners.
Against this background, from the viewpoint of its low cost, robustness and recyclability, it has begun to attract attention as a rotating machine used in automobiles and others.
[0007]
However, since this reluctance motor has operating conditions that are significantly different from those of other motors, satisfactory characteristics could not always be obtained using electromagnetic steel sheets that have been conventionally developed.
[0008]
[Problems to be solved by the invention]
The present invention has been developed in view of the above circumstances, it aims to propose an advantageous method for producing non-oriented electrical steel sheet capable of effectively improving the reluctance motor in particular the efficiency of a switched reluctance motor And
[0009]
[Means for Solving the Problems]
Now, the inventors not only investigated the magnetic properties of steel sheets in detail, but also used them to actually produce switched reluctance motors and examined the relationship between the actual machine properties and material properties in detail. .
As a result, in order to increase the motor efficiency of the actual machine, it was found that it is effective to reduce the iron loss of the material at a higher frequency than the commercial frequency and in the high magnetic flux density region, and to reduce the residual magnetic flux density. It was.
The present invention is based on the above findings.
[0013]
That is, the gist configuration of the present invention is as follows.
1. After heating steel slab containing C: 0.0050 mass% or less, Si: 0.1-7.0 mass% and Mn: 0.1-2.5 mass%, adjusted to the component composition of the remaining Fe and inevitable impurities at 1200 ° C. or lower, At the time of hot rolling and then cold rolling twice, including one or intermediate annealing, at least 25% reduction was applied in a temperature range of 60 ° C or higher, and then finish annealing was performed at a temperature of 850 ° C or higher. A method for producing a non-oriented electrical steel sheet for a reluctance motor iron core, wherein cooling is performed under a tension of 4 MPa or less.
2. In the above 1, the steel slab component further contains Al in a range of 0.1 to 2.5 mass%, or has a composition in which Al is suppressed to 0.01 mass% or less, and is non-directional for a reluctance motor core. A method for producing electrical steel sheets.
3. 3. A method for producing a non-oriented electrical steel sheet for a reluctance motor core, wherein the steel slab component further comprises a composition containing P: 0.1 mass% or less in the above 1 or 2.
4). In any one of the above 1 to 3, the steel slab component further comprises one or two kinds selected from Sb: 0.005 to 0.120 mass% and Sn: 0.005 to 0.25 mass%. Manufacturing method of non-oriented electrical steel sheet for reluctance motor iron core.
5. In any one of the above 1 to 4, the steel slab component further comprises one or more selected from Ni, Cu, and Cr at a composition containing 10 mass% or less, respectively, for a reluctance motor core Manufacturing method for non-oriented electrical steel sheets.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be specifically described below.
The inventors first obtained various commercially available switched reluctance motors, produced dies that could be processed into the same shape as these, and punched various steel plate materials to produce motors. And the maximum efficiency of these motors was measured. The motor efficiency is expressed as a ratio of output to input, that is, motor efficiency = (output / input) × 100 (%). Therefore, the number of rotations of the motor was variously changed, and the maximum value of the motor efficiency (maximum efficiency of the motor) was obtained.
In evaluating the material properties, magnetic measurements were performed using Epstein test pieces (referred to as L pieces and C pieces, respectively) in the rolling direction and the direction perpendicular to the rolling direction. In addition to the commercial frequency, magnetic measurements were made in the high frequency range up to 50 kHz, and these were analyzed in detail.
As a result, the average iron loss W _15/800 (L + C) in the rolling direction (L direction) and the direction perpendicular to the rolling direction (C direction) at an excitation magnetic flux density of 1.5 T and an excitation frequency of 800 Hz and a magnetic flux density of 1.8 T It was found that the influence of the residual magnetic flux density Br _1.8 on the motor efficiency when magnetized until the motor is particularly large.
[0015]
Fig. 1 shows the results of an investigation of the effects of material iron loss W _15/800 (L + C) and residual magnetic flux density Br _1.8 on the maximum efficiency of a switched reluctance motor rated at 300W.
As shown in the figure, the maximum efficiency of the motor is particularly good when the iron loss W _15/800 (L + C) is 150 W / kg or less and the residual magnetic flux density Br _1.8 is 1.0 T or less. It turns out that it is.
[0016]
As described above, when a material satisfying the appropriate range of the present invention with the iron loss W _15/800 (L + C) and the residual magnetic flux density Br _1.8 is used, the reason why particularly good motor characteristics are obtained is as follows. Although not necessarily clear, it can be inferred as follows.
In other words, there are several methods for exciting the switched reluctance motor, but the main method is one-side excitation in which there is no reversal of magnetic poles in the teeth portion of the stator.
[0017]
That is, first of all, for the iron core material, the magnetic flux density B in the BH loop, so-called hysteresis loop, is magnetized only on one side of positive or negative.
FIG. 2 (b) shows this state in comparison with a normal state (FIG. 2 (a)).
In this case, since the magnetic flux changes without reversing the magnetizing force, the starting point in the magnetization process is the position of the residual magnetic flux density.
When this residual magnetic flux density is large, there arises a problem that magnetization characteristics and eddy current characteristics deteriorate.
Since the motor has an air gap between the stator and the rotor, the residual magnetic flux density is not so large in an actual motor. However, by reducing the residual magnetic flux density of the material, it is possible to reduce the residual magnetic flux density even in an actual motor, which contributes to the reduction of copper loss and iron loss, and high efficiency can be obtained. Conceivable.
[0018]
Second, the switched reluctance motor uses the change in magnetic flux density accompanying the change in magnetization during switching as its driving force for rotation, so the magnetic flux density applied to the iron core material is larger than that of a normal motor and is excited. The waveform deviates from the sine wave and is accompanied by a large distortion. Therefore, it is considered that the residual magnetic flux density described above is important when the magnetizing force is reduced from the high magnetic flux density region of 1.8T. Moreover, regarding the iron loss, it is considered that the magnetic flux density and the high frequency region are more important than the region studied for the conventional motor.
[0019]
As described above, the present invention has been completed as a result of detailed examination of material characteristics in a switched reluctance motor that has greatly different magnetization conditions from those of conventional motors while fully considering such special magnetization conditions. Is.
[0020]
Next, in the present invention, the reason why the component composition of the material is limited to the above range will be described.
C: 0.0050 mass% or less C expands the γ region and lowers the α-γ transformation point, and therefore, during annealing, the γ phase is formed in a film shape at the α grain boundary, thereby suppressing the growth of α grains. Basically, C needs to be reduced. Moreover, even if it contains a large amount of an α-phase stabilizing element such as Si or Al and a γ-phase is not generated at all temperatures, if the C content exceeds 0.0050 mass%, it may cause aging deterioration of iron loss characteristics. . Therefore, in this invention, the amount of C was limited to 0.0050 mass% or less.
[0021]
Si: 0.1-7.0 mass%
Si not only increases the specific resistance of steel and reduces iron loss, but also has the effect of reducing domain wall energy and reducing residual magnetic flux density. However, if the content is less than 0.1 mass%, the effect of addition is poor. On the other hand, if it exceeds 7.0 mass%, the saturation magnetic flux density is lowered and the magnetization characteristics are deteriorated, so Si is in the range of 0.1 to 7.0 mass%. Limited. Preferably it is 0.3-4.6 mass%.
Mn: 0.1-2.5 mass%
Mn also has the effect of increasing the specific resistance of steel and reducing iron loss, although not as much as Si and Al. Moreover, since there exists an effect which improves hot rolling property, it was decided to contain at least 0.1 mass%. However, if the content is too large, the cold rolling property deteriorates, so the upper limit was set to 2.5 mass%.
[0022]
Although the essential components have been described above, in the present invention, the following elements can be appropriately added as necessary.
Al: 0.1 to 2.5 mass% or Al: 0.01 mass% or less
Al, like Si, is an element effective for increasing the specific resistance of steel and reducing iron loss. For this purpose, it is preferable to add 0.1 mass% or more. However, if the content exceeds 2.5 mass%, the lubricity with the mold in continuous casting deteriorates and casting becomes difficult. Therefore, when Al is contained, the content is preferably in the range of 0.1 to 2.5 mass%.
In addition, when not used as a specific resistance improving element as described above, in the addition range of more than 0.01 mass% up to 0.10 mass% rather inhibits grain growth and deteriorates iron loss characteristics. Al is preferably suppressed to 0.01 mass% or less.
[0024]
P: 0.1 mass% or less P, although not as high as Si and Al, has the effect of increasing the specific resistance of steel and reducing iron loss, and improves the texture after cold rolling recrystallization by grain boundary segregation. Since there exists an effect which improves a density, you may add as needed. However, excessive grain boundary segregation inhibits grain growth and degrades iron loss, so the upper limit is made 0.1 mass%.
[0025]
Sb: 0.005 to 0.120 mass%
Sb not only improves the texture and improves the magnetic flux density, but also suppresses oxynitriding of the steel sheet surface layer, and further suppresses the formation of surface layer fine grains, thereby suppressing an increase in surface hardness and punching. It has the effect of improving workability. It is also an element useful for reducing the residual magnetic flux density. However, if the content is less than 0.005 mass%, the effect of addition is poor. On the other hand, if it exceeds 0.120 mass%, the grain growth is inhibited and the magnetic properties are deteriorated, so Sb is contained in the range of 0.005 to 0.120 mass%. It is preferable to make it.
[0026]
Sn: 0.005 to 0.25 mass%
Sn may be added for the same purpose as Sb. However, if the content is less than 0.005 mass%, there is no effect. On the other hand, if it exceeds 0.25 mass%, the grain growth is inhibited and the magnetic properties are deteriorated. The amount is preferably 0.005 to 0.25 mass%.
[0027]
In addition, since Ni, Cu, Cr, and the like are elements that increase the specific resistance, they may be added. However, if any of them exceeds 10 mass%, the rollability deteriorates, so it is preferable to add them at 10 mass% or less.
[0028]
Further, S forms precipitates and inclusions and inhibits the grain growth. Therefore, it is necessary to reduce the mixing thereof as much as possible, but it is acceptable if the mixing amount is 0.01 mass% or less.
[0029]
Next, a description will be given manufacturing conditions of the present invention.
The hot rolling conditions, for energy saving, the slab heating temperature was 1200 ° C. or less.
Further, when performing hot-rolled sheet annealing, it is difficult to improve the magnetic flux density unless the annealing temperature is 800 ° C. or higher. Therefore, it is preferable to perform in a temperature range of 800 ° C. or higher.
[0030]
Next, rolling is performed once or twice, including intermediate annealing. In this cold rolling, it is important to apply a reduction of at least 25 % in a temperature range of 60 ° C or higher in order to make the texture appropriate. It is.
In other words, in order to reduce the iron loss in the high frequency / high magnetic flux density region, it is ideal that the <100>, which is the easy axis of magnetization, is oriented on the average in the rolling direction and the direction perpendicular thereto. It is considered preferable to include <111> which is advantageous in a high magnetic flux density region. However, when the rolling temperature is less than 60 ° C. or the rolling reduction is less than 25%, the formation of the texture as described above becomes insufficient, and good magnetic properties cannot be obtained.
Such rolling can be achieved by Zenzimer rolling, but tandem rolling is more advantageous from the viewpoint of production efficiency.
[0031]
After the above cold rolling, finish annealing is performed, but if the annealing temperature at this time is less than 850 ° C, grain growth is insufficient, and good iron loss and low magnetic anisotropy cannot be obtained. The temperature should be 850 ° C or higher.
Furthermore, when the tension during cooling exceeds 4 MPa, the residual magnetic flux density characteristics deteriorate, so the applied tension during cooling is limited to 4 MPa or less.
[0032]
Example 1
The steel slab having the composition shown in Table 1 was heated to 1150 ° C. with a normal gas heating furnace, and then hot rolled into a hot rolled sheet having a thickness of 2.5 mm. Subsequently, after hot-rolled sheet annealing at 880 ° C. for 10 seconds, the final sheet thickness was 0.35 mm using a 4-stand tandem rolling mill. At this time, the fourth pass was performed under the conditions of the stand entrance temperature: 70 ° C. and the rolling reduction: 32%. Then, after finishing annealing at 920 ° C., cooling was performed under a tension of 3 MPa, and then coating treatment was performed to obtain a product plate.
Thus, Epstein test pieces in the L and C directions were collected from the product plate for material evaluation, and the magnetic properties were measured. We also made a prototype 300W switched reluctance motor and measured its motor efficiency.
The results obtained are summarized in Table 2.
[0033]
[Table 1]

[0034]
[Table 2]

[0035]
As is clear from Table 2, it is particularly good when a material with an iron loss W _15/800 (L + C) of 150 W / kg or less and a residual magnetic flux density Br _1.8 of 1.0 T or less is used as a material. Motor efficiency is obtained.
[0036]
Example 2
When manufacturing product plates using steel G, H, K, and L shown in Table 1, as shown in Table 3, tandem rolling conditions and annealing temperatures are variously changed to perform cold rolling and finish annealing. It was.
In addition, the tandem rolling mill used for cold rolling was composed of 4 stands, and among these, the one with the highest stand entry side temperature showed the entry side temperature and the reduction ratio. The slab heating, hot-rolled sheet annealing, and coating treatment were performed under the same conditions as in Example 1.
From the product plate thus obtained, Epstein test pieces in the L and C directions were collected for material evaluation, and the magnetic properties were measured. We also made a prototype 300W switched reluctance motor and measured its motor efficiency.
The results obtained are also shown in Table 3.
[0037]
[Table 3]

[0038]
As shown in Table 3, according to the present invention, an electromagnetic steel sheet having a low iron loss in a high frequency / high magnetic flux density region and a small residual magnetic flux density can be obtained. The motor efficiency of the trilactance motor could be improved significantly.
[0039]
【The invention's effect】
Thus, according to the present invention, it is possible to obtain a non-oriented electrical steel sheet having a low iron loss in a high frequency / high magnetic flux density region and a small residual magnetic flux density, and consequently magnetic characteristics in such a high frequency / high magnetic flux density region. A highly efficient reluctance motor can be obtained by using a steel plate having excellent resistance as a material.
[Brief description of the drawings]
FIG. 1 is a graph showing the effects of material iron loss W _15/800 (L + C) and residual magnetic flux density Br _1.8 on the maximum efficiency of a switched reluctance motor rated at 300 W.
FIG. 2 is a diagram comparing the difference between normal excitation and one-side excitation hysteresis loops (BH loops).

Claims (5)

  After heating a steel slab containing C: 0.0050 mass% or less, Si: 0.1 to 7.0 mass% and Mn: 0.1 to 2.5 mass%, adjusted to the component composition of the remaining Fe and inevitable impurities at 1200 ° C. or less, At the time of hot rolling and then cold rolling twice, including one or intermediate annealing, at least 25% reduction was applied at a temperature range of 60 ° C or higher, and then finish annealing was performed at a temperature of 850 ° C or higher. A method for producing a non-oriented electrical steel sheet for a reluctance motor iron core, which is then cooled under a tension of 4 MPa or less. The non-direction for a reluctance motor core according to claim 1, wherein the steel slab component further contains Al in a range of 0.1 to 2.5 mass% or has a composition in which Al is suppressed to 0.01 mass% or less. Method for producing an electrical steel sheet. The method for producing a non-oriented electrical steel sheet for a reluctance motor iron core according to claim 1 or 2, wherein the steel slab component further contains P: 0.1 mass% or less. The steel slab component according to any one of claims 1 to 3, wherein the steel slab component further includes one or two kinds selected from Sb: 0.005 to 0.120 mass% and Sn: 0.005 to 0.25 mass%. To manufacture a non-oriented electrical steel sheet for a reluctance motor iron core. The reluctance motor core according to any one of claims 1 to 4, wherein the steel slab component further contains one or more selected from Ni, Cu, and Cr at 10 mass% or less, respectively. Method for non-oriented electrical steel sheet for use in a vehicle.

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