JP2004122218A - Device and method for manufacturing grain oriented electrical steel sheet superior in magnetic characteristic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser irradiation device that can deal with high moving speed of a steel sheet in the manufacturing technique of a grain oriented electrical steel sheet in which magnetic characteristics are improved by laser irradiation. <P>SOLUTION: In the device and method for manufacturing a grain oriented electrical steel sheet that excels in the magnetic characteristics; the device is constituted of N independent beam irradiation units that divide a laser beam outputted from one laser generator into N beams at equal intervals timewise and that simultaneously scan and emit the beam; the beam irradiation units are arranged so that each beam scanning position is aligned at the same position along the rolling direction; and a distance D(m) between the irradiation position of a first beam irradiation device arranged most upstream in the rolling direction and that of the m-th beam irradiation device following it satisfies a relation below. D(m)=N×k(m)×P1+(m-1)×P1, assuming that m is an integer fulfilling 2≤m≤N, that k(x) is 0 or an arbitrary positive integer, and that k(x1)<k(x2) is expressed if x1<x2. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus and a method for producing a grain-oriented electrical steel sheet having excellent magnetic properties.
[0002]
[Prior art]
Conventionally, as disclosed in Patent Document 1 and the like, in a method of manufacturing a grain-oriented electrical steel sheet, a glass film is formed on the surface of the steel sheet, and after applying an insulating coating, mechanical stress strain is introduced into the steel sheet surface, A method is described in which a magnetic reflux magnetic domain is formed to subdivide the 180 ° magnetic domain and reduce iron loss.
[0003]
The point of the apparatus in this method is that the laser beam is repeatedly scanned and irradiated at a high speed in a direction substantially perpendicular to the rolling direction in accordance with the moving speed of the steel sheet in the rolling direction so that the irradiation interval Pl in the rolling direction becomes constant. It is in. In order to realize this, conventionally disclosed in Patent Document 2 is that a laser beam is divided into two equal parts in time by a rotating beam split mirror, and the steel plate is irradiated by an irradiation device arranged along the plate width direction. Has been scanned.
[0004]
The relationship of laser scanning parameters in this method will be described with reference to FIG. In FIG. 4, one divided beam irradiation apparatus in which the steel plate moving speed in the rolling direction is Vl (mm / s), the scanning speed in the plate width direction is Vs (mm / s), the scanning line interval in the rolling direction is Pl (mm). When the hit scanning width is Ws ′, since this method is a beam bisection method, the scanning width of one beam is Ws = 2 × Ws ′. If the scanning time of one divided beam is ts, the total scanning time Ts = 2 × ts of the two beams. Since the total movement amount in the steel sheet rolling direction within the time Ts corresponds to Pl, these parameters are connected by the following relational expression.
[0005]
Ts = 2 × ts = 2 × (Ws ′ / Vs) = Ws / Vs (1)
Pl = Ts × Vl = (Ws / Vs) × Vl (2)
Since Ts is the scanning repetition period of the beam, the reciprocal thereof is the beam runner repetition frequency Fs.
[0006]
Fs = 1 / Ts = Vl / Pl (3)
Here, in order to increase the production amount per unit time, it is considered to increase the rolling direction moving speed Vl of the steel sheet. Even in this case, the linear scanning line interval Pl greatly affects the magnetic characteristics and cannot be changed. Therefore, it is necessary to reduce the beam scanning time Ts from the equation (2). As a result, the beam scanning repetition frequency Fs increases in proportion to Vl from the equation (3). For example, when Vl = 5000 mm / s corresponding to 300 m / min in the rolling direction moving speed, when trying to achieve Pl = 5 mm generally used in the magnetic domain control of the electromagnetic steel sheet, Fs = 1000 Hz.
[0007]
By the way, the beam scanning method is realized by mirror vibration by a galvano motor as disclosed in Patent Document 2 or by rotation of a polygon mirror as disclosed in Patent Document 3. However, in the case of a galvano motor, the frequency that can be stably controlled for a long time is at most about 100 Hz, and cannot be used for the high-speed scanning as described above. The frequency in the case of a polygonal mirror corresponds to the product of the number of mirror surfaces h and the rotational speed Vr (rps). Here, assuming that one mirror of the polygon mirror is a square with one side a, and the circumscribed circle radius of the polygon mirror is R, the polygon mirror can be roughly designed by the following equation.
[0008]
Fs = h × Vr (4)
R = a / sin (2π / h) (5)
If Vr = 50 rps, which is a realistic value, is selected as the rotation speed, h = 20 is obtained from the equation (4), resulting in a icosahedron polygon mirror. Assuming that the mirror width a is an effective width a = 40 mm sufficient to receive a beam having a laser beam diameter of about 20 to 30 mm before focusing, in order to realize Fs = 1000 Hz, the radius R = from the equation (5). There is a problem that the size becomes 130 mm, and a large polygonal mirror is required. In consideration of the number of mirror surfaces, motor capacity, and controllability, the apparatus becomes large and expensive. The motor rotation speed Vr is proportional to the scanning speed Vs.
[0009]
When using a relatively low power laser, the heat input per unit area decreases as Vl increases, and the iron loss improvement effect is drastically reduced. As a result, there is a limit to the increase in Vl, that is, there is a restriction that Vr cannot be increased too much. In that case, there is a problem that the number of polygon mirrors increases from the equation (4), and the radius becomes larger than the equation (5). Therefore, even in the scanning method using a polygon mirror, the conventional irradiation method has a limit in increasing the steel plate moving speed and responding to the increase in production.
[0010]
[Patent Document 1]
Japanese Patent Publication No. 58-26405 [Patent Document 2]
JP-A-63-83227 [Patent Document 3]
Japanese Patent Laid-Open No. 10-204533
[Problems to be solved by the invention]
The present invention provides a laser irradiation apparatus that can cope with a high steel plate moving speed in a technology for producing a grain-oriented electrical steel sheet that improves magnetic properties by laser irradiation.
[0012]
[Means for Solving the Problems]
The present invention is an apparatus for producing a grain-oriented electrical steel sheet that improves the iron loss characteristics by scanning and irradiating a laser beam substantially perpendicular to the rolling direction of the steel sheet at a constant interval Pl, and is output from one laser device. A beam splitting device that splits the laser beam into N at regular intervals in time, and N independent lasers that receive each split beam and perform scanning irradiation with a constant line width Ws in synchronization with the beam splitter. The beam irradiation device is arranged so that the beam scanning position is aligned at the same position along the rolling direction, and the irradiation position of the first beam irradiation device arranged at the uppermost stream in the rolling direction is Then, the apparatus for producing a grain-oriented electrical steel sheet having excellent magnetic properties, characterized in that the distance D (m) from the irradiation position of the subsequent m-th beam irradiation apparatus satisfies the following relationship.
[0013]
D (m) = N * k (m) * Pl + (m-1) * Pl
However, m is a positive integer satisfying 2 ≦ m ≦ N. K (x) is 0 or an arbitrary positive integer, and k (x1) <k (x2) when x1 <x2.
[0014]
According to the present invention, the laser beam splitting device is a rotating disk that reflects a laser beam, and includes a laser beam reflecting mirror whose laser beam reflection angle periodically changes depending on the center angle of the disk. It is an apparatus for producing a grain-oriented electrical steel sheet having excellent magnetic properties.
[0015]
Furthermore, the present invention relates to a method of manufacturing a grain-oriented electrical steel sheet that improves the iron loss characteristics by scanning and irradiating a laser beam at a regular interval substantially perpendicular to the rolling direction of the steel sheet. A method for producing a grain-oriented electrical steel sheet having excellent magnetic properties, wherein the laser beam scanning speed and the irradiation laser power are changed in conjunction with each other.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail using examples.
[0017]
The present inventors increase Pl equivalently from equation (2) so that it is not necessary to increase the scanning frequency Fs even when the steel plate moving speed Vl is increased, that is, it is not necessary to decrease Ts. The inventors have studied the method and have arrived at the invention of the apparatus shown below.
[0018]
That is, the point of the present invention is that, conventionally, a laser beam output from one laser device is equally divided in time and distributed to laser irradiation devices arranged along the rolling direction. Furthermore, by fixing the arrangement position of the irradiation positions to a positional relationship determined by the desired Pl and the number of beam divisions N, and by setting the scanning irradiation interval of each irradiation apparatus to N × Pl, it is possible to completely control the irradiation positions between the irradiation apparatuses. Without being performed, scanning irradiation is performed by the downstream apparatus so as to automatically fill the gap between the scanning lines irradiated by the upstream apparatus. After irradiation by the most downstream apparatus, a desired scanning interval Pl The irradiation is performed at This operation will be described below with reference to FIG.
[0019]
FIG. 1 is a schematic diagram of an apparatus according to the present invention, which is an embodiment in which N is 3. FIG. The laser beam B0 output from the laser device 14 is equally divided into three beams B1, B2, and B3 in terms of time by the beam splitter 1. As shown in FIG. 3, the beam splitting apparatus 1 is composed of a rotary motor 2 and a reflecting disk mirror 3 rotated by the rotary motor 2. The reflection disk mirror 3 is a rotating disk that reflects the laser beam, and has a structure in which the laser beam reflection angle changes periodically depending on the center angle of the disk. In other words, the inclined portion of the disk is equally divided into a fan shape so that the central angles are equal, and the reflection angle arranged on each fan portion is changed to a step shape. Since the incident point of the laser beam is fixed, the reflection angle of the laser beam changes as the disk rotates as shown in the figure, and in this embodiment, the beam can be time-divided in three directions. Further, by providing a periodic slit in the circumferential direction at the beam reflection point of the disk, a transmitted laser beam can be used as a split beam.
[0020]
As shown in FIG. 1, the divided beams are received by the irradiation devices 4, 5, and 6, respectively. The laser beam is scanned by a polygon mirror 9 that is rotated by a motor 8 via a reflection mirror 7. Here, the motors 2 and 8 are phase-synchronized by the synchronizer 13 so that the polygon mirror faces a desired direction at the moment when the divided beams are distributed to the irradiation devices. The scanned beam is collected by the parabolic mirror 10, reflected by the plane mirror 11, and irradiated onto the steel plate 12. Each irradiation device 4, 5 and 6 has the same structure, and is arranged so that the scanning position is the same position along the rolling direction.
[0021]
Next, the movement of the scanning point of the irradiation beam and the arrangement of the irradiation position will be described with reference to FIG. The irradiation position of the first irradiation device 4 arranged on the most upstream side in the moving direction of the steel plate is L1 indicated by a solid line in the drawing, the starting point of the scanning line is S1, and the end point is E1. Similarly, the second and third irradiation devices 5 and 6 arranged on the downstream side are denoted by L2 (dotted line), S2, E2, and L3 (single-dotted line), S3, and E3. In this case, the irradiation point is repeatedly scanned in the order of S 1 → E 1 → S 2 → E 2 → S 3 → E 3 → S 1 → E 1. Here, the scanning positions are arranged so that the distance Dm between L1 and Lm satisfies the relationship of the following expression (6).
D (m) = N × k (m) × Pl + (m−1) × Pl (6)
Here, m is an integer satisfying 2 ≦ m ≦ N, that is, m = 2 and 3 in this embodiment. k (x) is 0 or any positive integer, and in x1 <x2, k (x1) <k (x2), and in this embodiment, k (2) = 2 and k (3) = 4 are selected. It is. In addition, Pl = 6 mm. Therefore, D1 = 38 mm and D2 = 76 mm from the equation (6). With such an arrangement, when the desired interval is Pl and the number of beam divisions is N, scanning is performed at a scanning frequency such that the irradiation interval of each apparatus is N × P1, that is, 3 × 6 = 18 mm. Thus, as shown in the figure, the scanning lines irradiated on the upstream side are sequentially filled with the scanning lines of the irradiation device arranged on the downstream side. As a result, a desired Pl = 6 mm is achieved after passing through the irradiation device on the most downstream side.
[0022]
In the apparatus according to the present invention, the effective irradiation interval of each irradiation apparatus is N times Pl, so that the expression corresponding to the expression (2) in the prior art is the following expression (7).
[0023]
Pl = Ts × Vl / N (7)
Further, from the relationship between Fs and Ts, the following equation (8) is obtained.
[0024]
Fs = 1 / Ts = Vl / Pl / N (8)
Comparing equation (8) with equation (3), it can be seen that in the present invention, the scanning frequency can be reduced to 1 / N at the same irradiation interval and steel plate moving speed, that is, a galvano used as a scanning device. Less load on the motor and polygon mirror. In other words, even with the same scanning frequency, up to N times the steel plate moving speed can be handled.
[0025]
Further, as a feature of the present invention, there is provided a control device 15 that increases or decreases the rolling direction moving speed Vl and scanning line speed Vs of the steel sheet and the irradiation laser power P in conjunction with each other. This is because even if Vl increases or decreases for some reason, if Vs increases or decreases in conjunction with it, Pl that has a large influence on the magnetic characteristics from equation (2) is maintained substantially constant, and also increases or decreases in accordance with the increase or decrease in Vs. Since the power density per unit area is not changed by increasing / decreasing the laser power P, the same thermal strain can be applied, and stable magnetic domain control can always be performed.
[0026]
【The invention's effect】
According to the present invention, it is possible to perform laser irradiation that can cope with high-speed steel sheet movement, and mass production of grain-oriented electrical steel sheets having excellent magnetic properties becomes possible.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of an apparatus configuration according to the present invention.
FIG. 2 is an explanatory diagram relating to a beam irradiation position in an apparatus according to the present invention.
FIG. 3 is a schematic diagram of a beam splitter.
FIG. 4 is an explanatory diagram regarding a beam irradiation position in a conventional apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Beam splitting device 2 ... Beam splitting rotating disk motor 3 ... Beam splitting rotating discs 4, 5, 6 ... First, second and third beam irradiation devices 7, 11 ... Planar reflecting mirror 8 ... Polygon mirror rotating motor DESCRIPTION OF SYMBOLS 9 ... Polygon mirror 10 ... Parabolic mirror 12 ... Directional electromagnetic steel plate 13 ... Motor synchronizer 14 ... Laser apparatus 15 ... Steel plate moving speed, beam scanning speed, laser power proportional increase / decrease device

Claims (3)

In a directional electrical steel sheet manufacturing apparatus that improves the iron loss characteristics by scanning and irradiating a laser beam at a constant interval Pl perpendicular to the rolling direction of the steel sheet, the laser beam output from one laser apparatus is timed. A beam splitter that divides the beam into N at regular intervals, and N independent beam irradiators that receive each of the divided beams and scan and irradiate the beam with a constant line width Ws in synchronization with the beam splitter. The beam irradiation device is arranged such that the beam scanning position is aligned at the same position along the rolling direction, and the irradiation position of the first beam irradiation device arranged at the uppermost stream in the rolling direction, and the m-th subsequent to it. An apparatus for producing a grain-oriented electrical steel sheet having excellent magnetic properties, characterized in that a distance D (m) from the irradiation position of the second beam irradiation apparatus satisfies the following relationship.
D (m) = N * k (m) * Pl + (m-1) * Pl
However, m is a positive integer satisfying 2 ≦ m ≦ N.
k (x) is 0 or any positive integer, and k (x1) <k (x2) when x1 <x2. 2. The laser beam splitting device according to claim 1, wherein the laser beam splitting device is a rotating disk that reflects the laser beam, and includes a laser beam reflecting mirror that periodically changes the laser beam reflection angle depending on the center angle of the disk. An apparatus for producing a grain-oriented electrical steel sheet having excellent magnetic properties. In a method for manufacturing a grain-oriented electrical steel sheet that improves the iron loss characteristics by scanning and irradiating a laser beam at regular intervals with respect to the rolling direction of the steel sheet, the moving speed of the steel sheet in the rolling direction, the laser beam scanning speed, and the irradiation laser A method for producing a grain-oriented electrical steel sheet having excellent magnetic properties, characterized by changing power in conjunction.

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