KR20130128214A - Oriented electrical steel sheets and method for manufacturing the same - Google Patents

Abstract

The present invention relates to an oriented electrical steel sheets and a manufacturing method thereof. Linear grooves are formed on the surface of the oriented electrical steel sheets in a width direction. The groove is formed to have first and second lateral surfaces facing each other on the electrical steel sheets. A lower width (W2) is 10 um or less. A groove forming factor (DG/W2) is in a range of 0.3-2.8. The depth of the linear grooves which are adjacent is different. The DG is a vertical distance from the surface of the steel sheet to the bottom center. The W2 is a distance in a width direction of the steel sheet from the bottom center of the groove to a fixing unit formed at the first and second lateral surfaces.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a directional electric steel sheet,

The present invention relates to a directional electric steel sheet and a method of manufacturing the same, and more particularly, to a directional electric steel sheet in which grooves having different depths by laser irradiation are formed on the surface of a steel sheet to miniaturize magnetic grooves of the steel sheet.

Directional electric steel sheets are used as iron core materials of electric devices such as transformers. In order to reduce electric power loss of electric devices and increase efficiency, steel sheets having magnetic properties with high iron loss and high magnetic flux density are required.

Generally, a directional electric steel sheet refers to a material having a texture (also referred to as a "goss cluster texture") in which the {110} <001> direction is oriented in the rolling direction through hot rolling, cold rolling and annealing. In such a directional electrical steel sheet, the {110} < 001 > direction is excellent in magnetic properties as the orientation degree of the iron in a direction in which magnetization is easy.

In order to improve the magnetic properties of the oriented electrical steel sheet, a method of refining the magnetic domain is used. As the magnetic domain refining method, the method of dividing the magnetic domain by the stress relieving annealing can be classified into the transient magnetic domain refinement and the permanent magnetic domain refinement have.

The temporary magnetic microfabrication technique is a domain refinement technique which miniaturizes a magnetic domain by forming a 90 DEG domain in order to minimize self-elastic energy generated by applying a local compressive stress to the surface by thermal energy or mechanical energy. On the other hand, the technique of microminiaturization of the temporal magnetic domain is a laser magnetic domain refining method, a ball scratching method, a plasma or ultrasonic wave magnetic domain refining method according to an energy source for finely domaining.

The permanent magnetic microfabrication method capable of maintaining the iron loss improving effect even after the heat treatment can be classified into an etching method, a roll method and a laser method. The etching method forms grooves on the surface of the steel sheet by an electrochemical corrosion reaction in an acid solution It is difficult to control the groove shape (groove width, groove depth), and since grooves are formed in the intermediate process (before decarburization annealing and high temperature annealing) to produce steel sheet, it is difficult to guarantee the iron loss characteristic of the final product. It has the disadvantage that it can not be done.

A method of finely pulverizing a permanent magnet by a roll is a method of forming a groove having a constant width and depth on the surface of a steel sheet by pressing a roll on the surface of the steel sheet and annealing the steel sheet after finishing the permanent magnetization to recrystallize the lower portion of the groove, Which has the disadvantages of stability, reliability, and process complexity in machining.

Since the permanent magnetization method using pulsed laser forms a groove by vapor deposition, it is difficult to secure the improvement rate of iron loss before heat treatment (stress removal annealing, SRA) because of suppressing the formation of molten part, and after the heat treatment, But also has a disadvantage in that it can not process the conveying speed of the steel sheet at a high speed.

Embodiments of the present invention are to provide an electric steel sheet in which the iron loss of a grain-oriented electrical steel sheet is improved by finishing a groove by forming a groove by melting an electric steel sheet by irradiating the surface of the steel sheet with a continuous wave laser, and a manufacturing method thereof.

In one or more embodiments of the present invention, there is provided a directional electrical steel sheet having a plurality of linear grooves formed on its surface in the width direction, the grooves having a first side and a second side facing each other on the electrical steel sheet, And the groove forming factor (D _G / W ₂ ) is in the range of 0.3 to 2.8, and the depths of the adjacent linear grooves are different from each other, characterized in that the bottom width (W ₂ ) A directional electric steel sheet may be provided.

D _G is the vertical distance from the surface to the bottom center of the steel sheet, and W ₂ is the widthwise distance from the center of the bottom of the groove to the solidification portion formed on the first and second side surfaces.

In one or more embodiments of the present invention, the diameter (B _W2 ) of the grooves in the rolling direction is 10 to 70 占 퐉 or 20 to 100 占 퐉, the length (B _L ) of the grooves in the width direction, Is 10 to 100 mu m, and the interval between the linear grooves having the same groove depth is 3 to 30 mm.

In one or more embodiments of the present invention, a solidification portion formed by solidification of the molten by-product of the steel sheet during the groove forming process is removed between the first side and the second side, and at least one of the first, And the solidified portion formed on the first side or the second side occupies 2% or more of the side distance (C), and the solidified portion formed on the first side or the second side occupies 2% or more of the side distance (C) . However, the side distance C is the shortest distance among the linear distances from the surface portion where the steel sheet is not melted to the bottom center of the groove.

In one or more embodiments of the present invention, the solidification portion is reduced in thickness toward the bottom surface and formed thicker toward the surface portion of the steel sheet.

In one or more embodiments of the present invention, the electrical steel sheet is a directional electrical steel sheet having been subjected to high temperature annealing and tension coating for secondary recrystallization or a directional electrical steel sheet having undergone high temperature annealing and tension coating for secondary recrystallization .

In one or more embodiments of the present invention, the step of forming the grooves may include removing the molten by-products of the electrical steel sheet formed on the first, second side, or bottom surface by air blowing or suction, So that at least one side of the first, second side, and bottom surface is exposed.

In one or more embodiments of the present invention, a laser beam having a frequency range of from 200 Hz to 8.5 kHz is irradiated to the surface of the electrical steel sheet before or after tension coating on the electrical steel sheet to form linear grooves having different depths in the rolling direction forming a linear groove; And removing stress-relieving heat treatment of the electric steel sheet on which the line-shaped grooves are formed; A method of manufacturing a directional electrical steel sheet comprising the steps of:

In one or more embodiments of the present invention, the shape of the laser irradiated on the surface of the steel sheet may be spherical or oval, and the width of the laser in the rolling direction is within 60 μm, The length of the laser beam in the width direction of the steel sheet is within 90 占 퐉 when the shape of the laser is spherical and within 150 占 퐉 when the shape of the laser is oval.

In one or more embodiments of the present invention, the irradiation distance (D _S ) of the laser in the rolling direction is 3 mm to 30 mm, and the irradiation of the laser is divided into 3 to 6 And the line speed of the electrical steel sheet is 15 m / min or more.

In one or more embodiments of the present invention, a pair of laser generators for irradiating a steel plate to generate a laser for melting a surface; A pair of scanner mirrors for respectively scanning the laser beams emitted from the pair of laser generating units; A pair of total reflection mirrors that totally reflect the laser beams passed through the pair of scanner mirrors; A pair of shaping mirrors for controlling the shape of an incident beam incident on the steel plate via the pair of total reflection mirrors; A shared polygon scanner mirror for reflecting the laser beams passed through the pair of shaping mirrors in opposite directions; And a focus mirror for adjusting a focal distance of the incident beam incident on the steel plate according to the moving speed of the steel plate. The magnetic steel sheet may be provided with a magnetic micro-finizing apparatus.

The pair of shaping mirrors of one or more embodiments of the present invention are characterized in that their curvatures are different from each other and are attached to the shared polygon scanner mirror so that the rotational speed of the shared polygon scanner mirror is varied according to the moving speed of the steel sheet And a beam bumper for irradiating only a laser having an angle capable of forming a linear groove between the shared polygon scanner mirror and the focus mirror can be further included .

In one or more embodiments of the present invention, molten by-product removing means that removes molten by-products generated upon melting of the steel sheet surface by laser irradiation; As shown in FIG.

Embodiments of the present invention can form a groove even at a high line speed by forming a line-shaped groove by forming a line-shaped groove having a different depth by irradiating a laser on the surface of an electric steel sheet to reduce the iron loss by miniaturizing the magnetic domain, Even after the stress relieving annealing, the effect of miniaturization of the magnetic domain by the groove formation can be maximized.

1 shows a surface of an electrical steel sheet according to an embodiment of the present invention.
2 is a cross-sectional view of a line-shaped groove formed in parallel according to an embodiment of the present invention.
3 is a cross-sectional view taken along line AA ′ of FIG. 1.
4 is a detailed sectional view of a line-shaped groove according to an embodiment of the present invention.
5 is a configuration diagram of a magnetic domain refinement apparatus according to an embodiment of the present invention.
6 is a view showing a shape and a mode of a continuous wave laser beam according to an embodiment of the present invention.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, it is to be understood that the present invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. It is intended that the disclosure of the present invention be limited only by the terms of the appended claims. Like reference numerals refer to like elements throughout the specification.

The present invention is characterized in that a continuous wave laser is irradiated to the surface of a steel sheet before the final coating of the secondary recrystallization is completed to form linear grooves having different depths so as to maintain the magnetic fineness after the heat treatment, The present invention relates to a technology for miniaturization of a steel plate.

1 is a schematic view of an electric steel plate in which linear grooves having different depths by a continuous wave laser beam are formed in parallel in accordance with an embodiment of the present invention, FIG. 2 is an enlarged view of a part of FIG. 1, FIG. 3 is a cross-sectional view of an electric steel sheet on which a linear groove having different depths according to an embodiment of the present invention is formed; FIG. 3 is a cross- Sectional view taken along line AA 'of FIG.

1 to 3, in the embodiment of the present invention, a line-shaped groove 90 is formed on the surface of the electric steel plate 10 perpendicular to the rolling direction of the electric steel plate 10, The grooves 90 have a first side surface 31 and a second side surface 33 facing each other.

2 shows two portions of the radiation 20 formed on the steel plate 10 of Fig. 1 in the XY plane. It is shown that the groove 90 is formed as the surface of the steel plate 10 melts as the laser is irradiated . Where B _W is the diameter of the groove 90 in the rolling direction Y and B _L is the length of the groove 90 in the width direction X and D _S is the length of the groove 90 in the rolling direction Y, Means the irradiation distance.

3, a continuous wave laser is applied to the surface of the electric steel plate 10 to form a line-shaped groove 90 on the surface of the electric steel plate 10, A groove 90 is formed by melting the surface portion of the steel sheet 10 so that a solidification portion 35 which is a by-product of melting is formed on the first and second side surfaces 35 of the groove 90. 4, the thickness of the solidification portion 35 decreases toward the bottom surface, becomes thicker toward the surface portion of the steel sheet, and the groove 90 is formed to be narrower toward the bottom surface . The molten by-product of the electrical steel sheet 10 may solidify and form a solidified portion on the bottom surface between the first side surface 31 and the second side surface 33. The first and second side surfaces 31, 33 and the bottom surface may be exposed.

Further, in the embodiment according to the present invention, the molten by-products formed on the surface portion of the electric steel sheet by laser irradiation are removed by air blowing or suction. The solidification portion 35 formed in the groove by air blowing or suction is generated simultaneously or independently on the groove bottom surface and the first and second side surfaces 31 and 33. 4 shows that the solidification portion 35 is formed on the first and second side surfaces 31 and 33 and the solidification structure of the molten by-product is formed only on the first and second sides 31 and 33 of the groove 90 It is possible to inject molten metal formed in the groove 90 by laser irradiation and blow it out to the outside or blow to move to the first and second side surfaces 31 and 33 of the groove 90. [ As described above, in the embodiment of the present invention, the solidification portions 35 of the first and second side surfaces 31 and 33 may be removed as shown in FIG.

As shown in FIG. 5, the molten by-products formed on the bottom surface of the groove 90 may be removed using the molten by-product removing means 85 to prevent the solidification portion 35 from being formed on the bottom surface of the groove.

In the embodiment of the present invention, the solidification portion 35 of the molten metal is formed on the sidewall (inner wall surface) of the groove 90 to refine the magnetic domain. The solidification portion 35 has a 2% Or more. The side distance C in the embodiment according to the present invention is set such that the shortest distance of the straight line distance from the surface portion of the steel sheet 10 where melting has not occurred to the bottom center of the groove 90 it means. When the portion occupied by the solidifying portion 35 is less than 2% of the first or second side distance C, the effect of improving the iron loss before the heat treatment is lowered, so that the occupancy rate of the side distance is set to 2% or more.

The electrical steel sheet 10 may be a directional electrical steel sheet and the directional electrical steel sheet may be a GOSS texture in which the steel sheet 10 has a texture of {110} < 001 > It is a soft magnetic material with excellent magnetic properties in the rolling direction.

Directional electric steel sheets are used as iron core materials for transformers, motors, generators, and other electronic devices because of their excellent magnetic properties in the rolling direction. Generally, the production of directional electric steel sheets is performed by using a slab produced by a continuous casting process Hot rolling → preliminary annealing → cold rolling → decarburization annealing → high temperature annealing → planarization annealing and insulation coating → cleaning and laser treatment.

The electrical steel sheet 10 to which the laser irradiation is performed may be a steel sheet 10 after completion of the high temperature annealing process for causing the secondary recrystallization of the electrical steel sheet 10 to be completed and the application of the tension coating or completion of the high temperature annealing process, Can be used. That is, a cold rolled sheet, a decarbonized annealed sheet, a high temperature annealed sheet, or the like can be used.

In FIG. 3, a plurality of grooves 90 having different depths according to an embodiment of the present invention are formed. In FIG. 3, B _W1 and B _W2 denote grooves 90 in the rolling direction of the grooves 90, in diameter, W ₂ is the width of the first or second aspect solidified portion 35, the steel sheet 10 to the formed (31, 33) in the bottom center of the groove 90 to the lower width of the groove 90 And DG ₁ and DG ₂ denote vertical distances from the surface of the steel plate 10 to the bottom center, respectively, at the depths of the grooves 90 having different depths. When the depth of the groove 90 is deep, the iron loss is reduced. In addition, since the groove 90 is formed to be shallow with a small output when forming the adjacent groove 90, in the embodiment of the present invention, 90 are formed in two dimensions.

In the embodiment of the present invention, the bottom width W ₂ of the groove 90 is less than 10 μm, and the diameter of the groove 90 in the rolling direction is 20 to 100 μm, And when the depth of the groove 90 is shallow, it is limited to 10 to 70 mu m. The depths DG ₁ and DG ₂ of the groove 90 are formed such that the groove formation factor D _G / W ₂ is in the range of 0.3 to 2.8 based on the diameter of the groove 90 do.

At this time, if the groove forming factor is less than 0.3, the iron loss improving effect is not exhibited. If it exceeds 2.8, the magnetic flux density and the iron loss deterioration before heat treatment are not preferable. Accordingly, in the embodiment according to the present invention, the range is limited to the above range in order to secure the iron loss improving effect after the heat treatment. This can suppress the occurrence of defects under the grooves 90 that may occur in the roll press- It is stable on the side. A continuous wave laser is used to form the grooves 90 on the surface of the steel sheet 10 so as to accompany the formation of the molten and re-welded portions 35 of the steel sheet 10 So that the laser is irradiated at 85 to 95 degrees with respect to the traveling direction of the steel plate 10. [

When the diameter of the groove 90 in the rolling direction is smaller than 10 mu m, the effect of improving the iron loss after heat treatment is not exhibited. When the diameter is larger than 100 mu m, the heat effect by the continuous wave laser is large, , And the diameter of the groove 90 in the rolling direction in the embodiment according to the present invention is limited to the above range since the magnetic flux density deteriorates remarkably.

In the embodiment of the present invention, the length (B _L ) of the groove 90 in the width direction is limited to 10 to 100 탆. If the length (B _L ) of the groove 90 in the width direction is 10 탆 The effect of improving the iron loss before the heat treatment is not exhibited. When the thickness is 100 m or more, the magnetic flux density before the heat treatment and the iron loss are deteriorated.

In the embodiment of the present invention, the interval D _s of the laser radiation 20 is limited to 3 to 30 mm in the rolling direction in order to secure the improvement rate of the iron loss after heat treatment to 10% or more. To minimize iron loss of the steel sheet 10 by minimizing the influence of the affected part (HAZ, Heat Affected Zone). In addition, in the embodiment of the present invention, when the depth of the grooves 90 of the melted portion is differently formed during the continuous wave laser irradiation and the depth of the grooves 90 by melting is more than 30% It is possible to miniaturize the steel plate 10 even at a high line speed.

In addition, since the grooves 90 having different depths can be formed on the surface of the steel sheet 10 by one polygon scanner mirror 60, the magnetic flux density of the steel sheet 10 can be prevented from deteriorating.

Hereinafter, a method of manufacturing the electrical steel sheet 10 according to the embodiment of the present invention will be described in detail with reference to FIGS. 5 and 6. FIG.

FIG. 5 is a configuration diagram of a laser beam optical system according to an embodiment of the present invention, and FIG. 6 is a diagram and a mode of a laser beam according to an embodiment of the present invention.

As shown in FIG. 6, in the embodiment of the present invention, the shape of the continuous wave laser irradiated on the surface of the electric steel plate 10 to form the groove 90 may be spherical or oval, (single mode) shape. 6 (a) and 6 (b) show spherical or elliptical laser shapes, and FIGS. 6 (c) and 6 (d) show the Gaussian mode of each laser. Mode.

In the embodiment of the present invention, the continuous wave laser beam is irradiated at a frequency of 200 Hz to 8.5 kHz to the surface of the cooled steel sheet 10 or the coated steel sheet 10 after the final insulating coating is applied and dried to form the grooves 90 However, if the frequency of the laser beam is within 200Hz or 8.5KHz or more, the depth of the groove 90 does not change at the same laser output, irradiation distance, and line speed, so that it can not be applied to a high line speed. Is limited to 200 Hz to 8.5 kHz. Further, it is possible to form the groove 90 by melting by irradiating the laser beam within the above frequency range.

A groove (90) diameter in the rolling direction of electromagnetic steel plates 10 _(W B) is preferably from 10 to 20 or to a 70㎛ ~ 100㎛, the rolling direction width of the laser is irradiated on a surface of the electrical steel sheet 10 for this, Mu m or less. Further, the width direction groove (90) length _(L B) is a plate (10) in the width direction length of the laser irradiated to the steel plate 10. To this end surface, to a 10㎛ to 100㎛ of the steel plate 10, the When the shape of the laser is spherical, it is within 90 占 퐉. When the shape of the laser is oval, it is within 150 占 퐉.

Further, the rolling direction irradiation distance (D _S) is 3mm to and to be 30mm, continuous wave lasers and irradiated to distinguish 3-6 pieces with respect to the width direction of the steel plate 10, the first side or the second side surface (31, 33 ) Is irradiated with a continuous wave laser so as to occupy 2% or more of the side distance.

In order to manufacture the electric steel plate 10 having different depths of the grooves 90 as in the embodiment according to the present invention, the magnetic microfabrication apparatus (laser optical system) shown in Fig. 5 is used.

Referring to FIG. 5, the magnetic microfabrication apparatus according to the embodiment of the present invention includes a pair of laser generating units 25 and 26 for irradiating the surface to generate a laser for melting the surface, A pair of scanner mirrors 30 and 31 for blocking unnecessary laser beams among the laser beams generated from the laser mirrors 25 and 26 and scanning the laser beams passed through the pair of scanner mirrors 30 and 31, A pair of total reflection mirrors 40 and 41 and a pair of shaping mirrors 50 and 51 for controlling the shape of an incident beam incident on the steel plate 10 via the pair of total reflection mirrors 40 and 41, A shared polygon scanner mirror 60 for reflecting the laser beams passed through the pair of shaping mirrors 50 and 51 in the opposite directions and a light source unit 60 for reflecting incident light incident on the steel plate 10 according to the moving speed of the steel plate 10, And focus mirrors 80 and 81 for adjusting the focal length of the beam. Further, the steel sheet surface may include molten by-product removing means 85 for removing the molten by-products generated upon melting by laser irradiation.

The pair of shaping mirrors 50 and 51 function to change the shape of the spherical shape 21 or the elliptical shape 22 with different curvatures and the shared polygon scanner mirror 60 has a circular shape, Each mirror irradiates a laser beam on the surface of the steel plate 10, and the adjacent mirror receives and continuously irradiates a laser beam incident at a minute time difference.

The shared polygon scanner mirror 60 is provided with a motor 62 for rotating the shared polygon scanner mirror 60. The motor 62 rotates the shared polygon scanner mirror 60, A control unit 64 for controlling the motor 62 is connected to the motor 62. The irradiation distance D _s of the groove 90 can be adjusted by controlling the rotation speed of the shared polygon scanner mirror 60 by the control unit 64.

The focal mirrors 80 and 81 adjust the focal length of the incident beam incident on the steel plate 10 after the shape is changed by the shaping mirrors 50 and 51, And further includes a pair of beam bumpers 70 and 71 between the focus mirrors 80 and 81 to prevent unnecessary laser irradiation. The beam bumper 70 or 71 is irradiated with only a laser having a predetermined angle capable of forming a line-shaped groove 90 in the electric steel plate 10, So that it can not be irradiated.

It is also possible to form a groove 90 from which molten byproducts are removed by scattering the molten byproducts formed on the surface of the steel sheet 10 or by setting the first and second sides 31 and 33 of the groove 90 to coagulation A portion 35 can be formed. By-product removing means 85, which is means for blowing air or the like or for removing the molten by-products by suction, can be used to scatter the molten by-products.

In the embodiment of the present invention, the electric steel plate 10 having grooves 90 having different depths can be manufactured by using the above-described magnetic domain refining apparatus. Particularly, in the embodiment of the present invention, since the shared polygon scanner mirror 60 is used to share one scanner and irradiate the laser, the number of mirrors that form two beam shapes can be minimized.

More specifically, the laser irradiation lines 20 formed by the continuous wave laser are formed parallel to the width direction, and the laser irradiation lines 20 can irradiate the laser in three to six divided lines with respect to the width direction have.

The laser is irradiated from the laser generators 25 and 26 through the scanner mirrors 30 and 31, the total reflection mirrors 40 and 41, the shaping mirrors 50 and 51, the shared polygon scanner mirror 60, 10) Beam is irradiated on the surface. The shape of the beam formed on the surface of the steel sheet 10 during the laser irradiation is the shape of the circle 21 or the ellipse 22. For this purpose, the shaping mirrors 50 and 51 having different curvatures are used.

3 shows a shape in which the depth of the groove 90 formed by the continuous wave laser is biased. The groove 90 formed by the continuous wave laser has a solidification portion 35 due to melting on the bottom and side surfaces, (35). The distance between the grooves 90, that is, the laser irradiation distance D _s , is adjustable by adjusting the rotational speed of the shared polygon scanner mirror 60 of the magnetic domain refinement apparatus. The linear polygon scanner mirror 60 is used to form a line-shaped groove 90 having a predetermined distance from the front and rear of the steel plate 10. For example, when the laser irradiation distance is 30 mm through each of the first and second focus mirrors 80 and 81, a linear groove 90 having a laser irradiation distance of 15 mm is formed in one electric steel plate 10 .

The molten by-products generated by the laser irradiation are removed by the molten by-product removing means 85.

Table 1 below shows the change in iron loss improvement ratio of a directional electric steel sheet by grooves formed on the surface of a steel sheet with a thickness of 0.23 mm by the continuous wave laser irradiation of the present invention and melting and re-solidification.

division Line
Speed
(m / min) B _W1 B _w2 D _S1 D _G / W ₂ D _S2 Before laser irradiation After SRA Iron loss improvement rate and magnetic flux density degradation rate ㎛ mm Dimensionless mm W17 / 50 % B8 % Inventory 1
(CW Laser / 500Hz) 20 25 50 10 2.6 4 0.83 0.74 10.8 1.93 1.93 0.0 0.84 0.73 13.1 1.92 1.92 0.0 Inventory 2
(CW Laser / 8.5kHz) 20 25 50 10 2.6 4 0.83 0.73 12.0 1.92 1.92 0.0 0.83 0.73 12.0 1.93 1.93 0.0 Inventory 3
(CW Laser / 7kHz) 20 25 50 10 2.9 4 0.83 0.74 10.8 1.92 1.92 0.0 0.84 0.81 3.6 1.93 1.93 0.0 Comparative Example
(Pulse Laser /
Discontinuous groove) 3 50 90 5 2.3 6 0.83 0.81 2.4 1.92 1.9 1.0 0.83 0.81 2.4 1.93 1.9 1.6

In Table 1, D _S1 represents the case where the laser irradiation interval is large, and D _S2 represents the case where the laser irradiation interval is small. In the embodiment of the present invention, the laser beam is irradiated at an angle of 85 to 95 degrees with respect to the traveling direction of the steel sheet at a line speed of 15 mpm or more to make the depth of the groove 90 on the surface of the steel sheet 10 double, W ₂ ) of 10 μm or less and a depth of 3 to 30 μm, it is possible to improve the iron loss improvement ratio after heat treatment by 10% or more.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand.

It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be interpreted as being included in the scope of the present invention .

Claims (22)

In the directional electrical steel sheet formed with a plurality of linear grooves in the width direction on the surface,
Wherein the groove has a first side and a second side facing each other on the electrical steel sheet, the bottom width (W ₂ ) of the groove is within 10 μm, and the grooving factor (D _G / W ₂ ) 0.3 to 2.8, and the depths of the adjacent linear grooves are different from each other.
D _G is the vertical distance from the surface to the bottom center of the steel sheet, and W ₂ is the widthwise distance from the center of the bottom of the groove to the solidification portion formed on the first and second side surfaces. The method of claim 1,
Wherein at least one of the first and second side surfaces and the bottom surface is exposed between the first side surface and the second side surface by removing a solidification portion formed by solidification of the molten by- Steel plate. 3. The method of claim 2,
The grain-oriented electrical steel sheet, characterized in that the diameter (B _W2 ) of the groove in the rolling direction is 10 to 70 µm or 20 to 100 µm. 3. The method of claim 2,
And the length (B _L ) of the groove in the width direction is 10 to 100 占 퐉. 3. The method of claim 2,
The grain-oriented electrical steel sheet, characterized in that the spacing between the grooves of the same groove depth is 3 ~ 30mm. 6. The method according to any one of claims 1 to 5,
Wherein the line-shaped grooves are divided into 3 to 6 pieces with respect to the width direction of the steel plate. 6. The method according to any one of claims 1 to 5,
The solidification portion formed on the first side surface or the second side surface,
And occupies 2% or more of the side distance (C).
However, the side distance C is the shortest distance among the linear distances from the surface portion where the steel sheet is not melted to the bottom center of the groove. 6. The method according to any one of claims 1 to 5,
Wherein the electrical steel sheet is an electrical steel sheet having undergone high temperature annealing and tension coating for secondary recrystallization, or an electrical steel sheet before high temperature annealing for completion of tension annealing and secondary coating for secondary recrystallization. The method of claim 7, wherein
Wherein the solidifying portion has a thickness decreasing toward a bottom surface and a thickness increasing toward a surface portion of the steel sheet. Irradiating a laser having a frequency range of 200 Hz to 8.5 kHz on the surface of the steel sheet before or after tension coating the electrical steel sheet to form linear grooves having different groove depths in a rolling width direction; And
A step of heat-treating the electric steel sheet on which the line-shaped grooves are formed;
Wherein the method comprises the steps of: The method of claim 10,
The forming of the grooves may include removing the molten by-products of the electrical steel sheet formed on the first, second side, or bottom surface by air blowing or suction, Wherein at least one surface of the bottom surface is exposed. The method of claim 10,
Wherein the shape of the laser irradiated on the surface of the steel sheet is spherical or elliptical (oval). The method of claim 10,
Wherein the width of the laser in the rolling direction is within 60 占 퐉. The method of claim 10,
The length of the steel plate in the width direction of the steel plate,
When the shape of the laser is spherical, it is within 90 占 퐉,
And when the shape of the laser is elliptical, it is within 150 占 퐉. The method of claim 10,
Wherein the irradiation distance (D _S ) of the laser in the rolling direction is 3 mm to 30 mm. The method of claim 10,
Irradiation of the laser is a method for producing a grain-oriented electrical steel sheet, characterized in that irradiated divided into three to six with respect to the width direction of the steel sheet. The method of claim 10,
Wherein the line speed of the electrical steel sheet is 15 m / min or more. A pair of laser generators for generating a laser for irradiating the steel sheet to melt the surface;
A pair of scanner mirrors for respectively scanning the laser beams emitted from the pair of laser generating units;
A pair of total reflection mirrors that totally reflect the laser beams passed through the pair of scanner mirrors;
A pair of shaping mirrors for controlling the shape of an incident beam incident on the steel plate via the pair of total reflection mirrors;
A shared polygon scanner mirror for reflecting the laser beams passed through the pair of shaping mirrors in opposite directions; And
A focus mirror for adjusting a focal distance of an incident beam incident on the steel plate according to the moving speed of the steel plate;
Wherein the magnetic steel sheet is made of steel. 19. The method of claim 18,
The pair of shaping mirrors may be formed by,
Wherein the curvatures of the magnetic steel plates are different from each other. 19. The method of claim 18,
Further comprising a motor attached to the shared polygon scanner mirror for controlling the rotational speed of the shared polygon scanner mirror according to the moving speed of the steel sheet, and a controller for controlling the motor. 21. The method according to any one of claims 18 to 20,
Further comprising a beam bumper for irradiating only the laser beam having an angle that can form a linear groove between the shared polygon scanner mirror and the focus mirror. 21. The method according to any one of claims 18 to 20,
By-product removing means for removing a molten by-product generated when the steel sheet surface is melted by laser irradiation; Further comprising the step of:

Images