JP2001164343A - Non-oriented electrical steel sheet for high-efficiency motor with small processing deterioration and its manufacturing method - Google Patents

Abstract

(57) [Problem] To provide a non-oriented electrical steel sheet for a high-efficiency motor with extremely small performance deterioration when assembled into a motor. SOLUTION: C: 0.0050 wt% or less, Si: 1.0 to 4.5 wt%
%, Mn: 0.1 to 2.5 wt% and Al: 0.2 to 2.5 wt%, in a non-oriented electrical steel sheet having a composition containing a rolling direction (L direction), a direction perpendicular to the rolling direction (C direction), and a rolling direction. The magnetic flux density at 5000 A / m in the direction of 45 ° (D direction): B ₅₀ (L), B ₅₀ (C), B ₅₀ (D)
(1), (2) B 50 (L) / B 50 (C) ≦ 1.04
--- (1) ｛B ₅₀ (L) + B ₅₀ (C) -2B ₅₀ (D)｝ ≦ 0.2
--- Satisfy the relationship of (2).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-oriented electrical steel sheet for a high-efficiency motor with a small processing deterioration and a method for manufacturing the same, and more particularly, to a non-oriented electrical steel sheet, which is a material of the motor, by performing a process such as punching. In this case, the motor efficiency is advantageously improved by reducing the degree of deterioration of the motor iron loss with respect to the material iron loss.

[0002]

2. Description of the Related Art In recent years, as the demand for energy saving has been strengthened, the trend toward higher efficiency of electrical equipment has been increasing. In response to this, steel sheet manufacturers have been improving the magnetic properties of electrical steel sheets for electrical equipment by various means.

[0003] Among them, addition of Si is the most effective means for reducing iron loss by increasing the specific resistance of a steel sheet, and is widely used. Also, 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 a steel sheet and to avoid the effect of suppressing the grain growth due to the precipitation of fine AlN. In Japanese Patent Application Laid-Open No. 55-73819, Al
By adding and reducing the oxidized layer inside the steel sheet surface by adjusting the annealing atmosphere, good high magnetic field characteristics are achieved. Further, JP-A-54-68716, JP-A-58-25427
In the publication, while adding Al, REM and Sb are added in combination or refined to improve the texture, thereby reducing iron loss.

[0004] In addition, JP-A-61-87823 discloses that Al
Japanese Patent Application Laid-Open No. 3-274247 discloses a method of controlling the cooling rate of the steel sheet during the finish annealing by adding B, Sb, Sn, etc. together with Al to prevent oxynitridation. In Japanese Unexamined Patent Publication No. Hei 3-294422, while adding Al, by controlling cold rolling to reduce the LC characteristic ratio of the steel sheet, in Japanese Unexamined Patent Publication No. 4-63252, by adding Al and Mn in combination, JP-A-4-136138 discloses that Al
In addition to the addition of P, the ultra-low Si and the improvement of the texture by the addition of P and Sb achieve the improvement of the magnetic properties, respectively.

[0005] All of the above techniques have been linked to the improvement of the efficiency of electrical equipment using the same by improving the characteristics of the magnetic steel sheet itself. On the other hand, recently, the control technology of small rotating equipment has been improved due to the dramatic improvement of peripheral technology along with the performance improvement and price reduction of semiconductors, the rotation control by inverter has been performed, and the progress of permanent magnet material High-efficiency rotating machines such as DC brushless motors can be manufactured.

However, in this DC brushless motor, the shape of the motor core is becoming more and more complicated in order to take advantage of the performance of the magnet, and as a result, the characteristic deterioration due to the distortion at the time of machining the iron core increases, and Despite the use of iron core material, the performance when assembled into a motor has often not been sufficient. Thus, in the motor using the conventional material as described above,
It is difficult to further reduce iron loss, and improvement in motor efficiency has leveled off.

[0007]

SUMMARY OF THE INVENTION The present invention has been developed in view of the above-mentioned circumstances, and is intended to produce a non-oriented electrical steel sheet for a high-efficiency motor with extremely small performance deterioration when assembled into a motor. The purpose is to propose along with the method.

[0008]

Means for Solving the Problems The inventors of the present invention not only investigate in detail the magnetic properties of a material steel plate, but also actually manufacture a motor using the same, and examine the relationship between the actual machine characteristics and the material characteristics. As a result of detailed investigation, it was found that it is extremely effective to reduce the magnetic anisotropy of the material steel sheet and satisfy the predetermined relationship for the magnetic flux density in each direction in order to increase the motor efficiency of the actual machine. Was. The present invention is based on the above findings.

That is, the gist of the present invention is as follows. 1. C: 0.0050 wt% or less, Si: 1.0 to 4.5 wt%, Mn: 0.
The composition contains 1 to 2.5 wt% and Al: 0.2 to 2.5 wt%, and the rolling direction (L direction) and the direction perpendicular to the rolling direction (C direction)
And the direction at 45 ° to the rolling direction (D direction)
Magnetic flux density at 000 A / m: B ₅₀ (L), B ₅₀ (C), B
₅₀ (D) is the following formula (1), (2) B 50 (L) / B 50 (C) ≦ 1.04 --- (1) {B 50 (L) + B 50 (C) -2B 50 (D )｝ ≤ 0.2 --- Non-oriented electrical steel sheet for high-efficiency motors with low machining deterioration, satisfying the relationship of (2).

[0010] 2. In the above item 1, further, Sb: 0.005 to
Non-oriented electrical steel sheet for high-efficiency motors with low processing deterioration, containing 0.120 wt%.

3. C: 0.0050 wt% or less, Si: 1.0 to 4.5
After hot rolling, a steel slab having a composition containing wt%, Mn: 0.1-2.5 wt% and Al: 0.2-2.5 wt% is subjected to hot-rolled sheet annealing at 750 ° C. or higher, and then once or intermediate annealing. Including 2
Cold rolling at least in the temperature range of 60 ° C or higher.
A method for producing a non-oriented electrical steel sheet for a high-efficiency motor with small processing deterioration, characterized by applying a reduction of 25% or more and performing a finish annealing at a temperature of 850 ° C or more.

In the present invention, the iron loss characteristic of the target material steel sheet is 2.30 W / kg or less at W15 / ₅₀ .

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the invention will be described below. By the way, the present inventors first, various commercially available DC
A brushless motor was obtained, a mold capable of performing the same shape processing as these was created, and a motor was manufactured by punching out various steel sheet materials, and the magnetic properties of the materials and the degree of deterioration of motor iron loss were investigated. In evaluating material properties,
Not only the conventional Epstein evaluation in the rolling direction (L direction) and the direction perpendicular to the rolling direction (C direction), but also the rolling direction
Magnetic measurements were also performed on Epstein test pieces (L, C and D pieces) in a direction (D direction) forming 45 °. The collection and magnetic measurement of Epstein test specimens
Performed in accordance with the provisions of C 2550.

FIG. 1 and FIG. 2 show the results of an examination on the influence of the magnetic flux density in each direction of the material on the degree of deterioration of the motor iron loss with respect to the material iron loss. From FIGS. 1 and 2, the magnetic flux densities at 5000 A / m in the L direction, C direction and D direction of the material: B ₅₀ (L), B ₅₀ (C), and B ₅₀ (D) are given by the following equations (1),
_{(2) B 50 (L)} / B 50 (C) ≦ 1.04 --- (1) {B 50 (L) + B 50 (C) -2B 50 (D)} ≦ 0.2 --- relationship (2) It can be seen that good motor characteristics with a small motor iron loss deterioration rate can be obtained when the above condition is satisfied.

As described above, B ₅₀ (L) and B ₅₀ (C)
The reason why good motor efficiency can be obtained only when a material whose B ₅₀ (D) satisfies the above equations (1) and (2) can be inferred as follows. That is, the motor core is divided into a stator and a rotor, which are usually formed by punching a non-oriented electrical steel sheet. Since the motor cores are all circular, the shear deformation portion formed by punching faces various directions depending on locations. In particular, since the tips of the teeth of the stator occupy an important position in the exchange of magnetic flux with the rotor, reducing processing distortion is a point for reducing motor iron loss. Here, it is needless to say that, regardless of the shearing surface at the tip end of the tooth in any of the rolling direction, the 45 ° direction of rolling, and the direction perpendicular to the rolling direction, it is preferable that the deterioration due to processing be smaller.

The degree of deterioration due to shearing is affected by various factors such as shearing clearance and speed, but is most strongly influenced by the relative positional relationship between the shearing surface direction of shearing and the texture of the iron core material. You. This means that the relationship between the shear plane and the slip surface, strength, ductility, etc. of the material governs the shearability. On the other hand, the value of the material B ₅₀ is obtained by reflecting strong material texture. Therefore, reducing the anisotropy of B ₅₀ as in this invention, that only in the case of controlling small anisotropy of texture, even at a shear in either direction, small like anyone or crushed, therefore distortion is small Thus, it is considered that a process capable of smoothly passing the magnetic flux between the rotor and the stator has become possible. In addition, recently, in order to improve the workability of the winding, the stator core is divided, but the material of the present invention is such that the ratio of the sheared portion to the core area is increased. It is particularly effective in design.

Next, the reason for limiting the component composition of the raw material to the above-mentioned range in the present invention will be described. C: 0.0050 wt% or less C has the effect of expanding the γ region and lowering the α-γ transformation point. When the content of C is large, a γ phase is formed in a film at α grain boundaries during annealing, and the growth of α grains is suppressed.
C should basically be reduced. Further, even when a large amount of an α-phase stabilizing element such as Si or Al is contained and a γ-phase is not generated in the entire temperature range, aging deterioration of iron loss characteristics is caused.
The amount was limited to 0.0050 wt% or less.

Si: 1.0 to 4.5 wt% Si is a useful element that increases the specific resistance of steel and reduces iron loss, and at least 1.0 wt% must be added to obtain its effect. However, excessive addition increases the hardness and deteriorates the cold rolling property, so the upper limit was made 4.5 wt%.

Al: 0.2-2.5 wt% Al is a useful element that, like Si, increases the specific resistance of steel and reduces iron loss. To obtain its effect, it is contained in an amount of 0.2 wt% or more. If the amount is too large, the lubricity with the mold in continuous casting decreases and casting becomes difficult.
2.5 wt%.

Mn: 0.1 to 2.5 wt% Mn is an element which is not as effective as Si and Al, but has the effect of increasing the specific resistance of steel and reducing iron loss, and is also useful in improving hot rolling properties. Therefore, it was made to contain 0.1 wt% or more. However, if the content exceeds 2.5 wt%, the cold rolling property deteriorates, so the upper limit was set to 2.5 wt%.

Although the essential components have been described above, Sb, P, Ni, Cu, Cr and the like can be appropriately contained in the present invention. Sb: 0.005 to 0.120 wt% Sb not only improves the texture and improves the magnetic flux density, but also suppresses the oxynitridation of aluminum in the surface layer of the steel sheet, particularly, and further suppresses the generation of fine particles in the surface layer accompanying this. By suppressing the rise in surface hardness, and improving the punching workability,
It is a useful element that has various effects. However, if the content is less than 0.005 wt%, the effect of the addition is poor. On the other hand, if the content exceeds 0.120 wt%, the growth of crystal grains is inhibited, leading to deterioration of magnetic properties.
It is preferable to contain it in the range of wt%.

P: 0.1 wt% or less P, although not as much as Si and Al, has the effect of increasing the specific resistance of steel and reducing iron loss, and also has the effect of reducing the texture after cold rolling recrystallization due to grain boundary segregation. Since it has the function of improving the magnetic flux density, it is added as necessary. However, excessive grain boundary segregation impairs grain growth and deteriorates iron loss. Therefore, it is preferable to contain P at 0.1 wt% or less.

Ni, Cu, Cr: 10 wt% or less Ni, Cu, Cr, etc. may be added because they are elements for increasing the specific resistance. However, if the content exceeds 10 wt%, the rollability deteriorates.
Both are preferably added at 10 wt% or less.

Among the impurities, S is a precipitate,
Since inclusions are formed and the grain growth is impaired, it is desirable to reduce the content as much as possible, and particularly to reduce the content to 0.01% by weight or less.

Next, the manufacturing method of the present invention will be described. Although the hot rolling conditions are not particularly specified, it is desirable to perform the slab heating at 1200 ° C. or less from the viewpoint of energy saving. Thereafter, hot-rolled sheet annealing is performed, and the annealing temperature at that time needs to be 750 ° C or higher. This is because the hot-rolled sheet annealing temperature is 7
If the temperature is lower than 50 ° C., a sufficient improvement in magnetic flux density cannot be expected.

Further, in the subsequent cold rolling step, it is necessary to apply a reduction of at least 25% or more in a temperature range of 60 ° C. or more in order to make the assembled fiber proper. The reason for this is
Although it has not been clarified yet, it is considered that such deformation behavior by rolling and subsequent recrystallization by finish annealing are necessary for forming the texture required in the present invention. In addition, this rolling can be achieved also by Sendzimer rolling, but tandem rolling is more preferable from the viewpoint of production rate.

Further, if the final annealing temperature is lower than 850 ° C., the grain growth is insufficient and good iron loss cannot be obtained. Therefore, the final annealing is performed at a temperature of 850 ° C. or higher.

[0028]

EXAMPLE l A steel slab having the composition shown in Table 1 was heated to 1150 ° C. by a normal gas heating furnace, and then 2.6 mm hot-rolled.
A thick hot rolled sheet was used. Then, after hot-rolled sheet annealing at 850 ° C for 1 minute, the temperature was reduced to 0 by a four-stand tandem rolling mill.
Finished 35mm thick. At this time, the temperature at the entrance of the fourth stand was 80 ° C., and the rolling reduction was 30%. Then 890 ° C
To give a product plate. After coating, Epstein test specimens in the L, C, and D directions were sampled for material evaluation, and their characteristics were evaluated. Also, 300 W DC
A brushless motor was prototyped and the iron loss was measured. Table 2 shows the measurement results of the material characteristics and the motor characteristics.

[0029]

[Table 1]

[0030]

[Table 2]

As shown in Table 2, according to the present invention,
A non-oriented electrical steel sheet for a high-efficiency motor with a W _15/50 of 2.30 W / kg or less and a small processing deterioration has been obtained.

Example 2 In producing a product using the steels A and G shown in Table 1 as raw materials,
After performing the hot-rolled sheet annealing at the temperature shown in Table 3, the rolling was performed by changing the tandem rolling conditions in various ways, and then the same as in Table 3 was performed.
The product was subjected to finish annealing at the temperature shown in Table 1 below. The tandem rolling mill had four stands, and among those having the highest temperature on the entrance side of the stand, the entry side temperature and the rolling reduction were also described. After coating, L, C,
Table 4 shows the results obtained by collecting Epstein test specimens in the D direction and evaluating the characteristics, and also making a prototype of a 300 W DC brushless motor and measuring the efficiency.

[0033]

[Table 3]

[0034]

[Table 4]

[0035] As shown in Table 4, both non-oriented electrical steel sheets obtained in this invention has a W _15/50 is 2.30 W / kg or less, yet working deterioration is small, and therefore when the assembled motor It can be seen that good motor characteristics can be obtained.

[0036]

As described above, according to the present invention, it is possible to stably obtain a non-oriented electrical steel sheet having not only a small iron loss value but also a small work deterioration. An excellent motor having a significantly higher motor efficiency can be obtained.

[Brief description of the drawings]

FIG. 1 is a graph showing the influence of the magnetic flux density in each direction (B ₅₀ (L) / B ₅₀ (C)) on the iron loss deterioration rate of a motor.

Figure 2 is a graph showing the effect of the direction-specific magnetic flux density of the material on the iron loss deterioration rate of the motor _{(B 50 (L) + B} 50 (C) -2B 50 (D)).

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Nobuhiro Shiga 1-chome, Mizushima-Kawasaki-dori, Kurashiki-shi, Okayama Pref. 1-chome (without address) Inside Kawasaki Steel Corporation Mizushima Works (72) Inventor Akio Fujita 1-chome (without address) Mizushima Kawasaki-dori Kurashiki City, Okayama Prefecture F-term (reference) 4K033 AA01 CA03 RA03 5E041 AA02 AA11 AA19 CA04 HB05 HB07 HB11 NN01 NN13 NN17 NN18

Claims (3)

[Claims] 1. A composition containing C: 0.0050% by weight or less, Si: 1.0 to 4.5% by weight, Mn: 0.1 to 2.5% by weight, and Al: 0.2 to 2.5% by weight. Magnetic flux density at 5000 A / m in the perpendicular direction (C direction) and the direction at 45 ° to the rolling direction (D direction): B ₅₀ (L), B
₅₀ (C) and B ₅₀ (D) are calculated by the following equations (1) and (2) B ₅₀ (L) / B ₅₀ (C) ≦ 1.04 --- (1) ｛B ₅₀ (L) + B ₅₀ (C A non-oriented electrical steel sheet for a high-efficiency motor with small machining deterioration, characterized by satisfying the relationship of -2B ₅₀ (D)｝ ≤ 0.2 --- (2). 2. The non-oriented electrical steel sheet according to claim 1, further containing 0.005 to 0.120 wt% of Sb, and having a small processing deterioration and for a high-efficiency motor. 3. A steel slab having a composition containing C: 0.0050% by weight or less, Si: 1.0 to 4.5% by weight, Mn: 0.1 to 2.5% by weight and Al: 0.2 to 2.5% by weight, after hot rolling, Hot-rolled sheet annealing at 750 ° C or more, and then cold rolling once or twice including intermediate annealing, applying at least 25% reduction at a temperature range of 60 ° C or more and finishing at a temperature of 850 ° C or more A method for producing a non-oriented electrical steel sheet for a high-efficiency motor with small processing deterioration, characterized by performing annealing.