JP2002121618A - Equipment for manufacturing grain-oriented electrical steel sheets with excellent magnetic properties - Google Patents

Abstract

(57) [Summary] [Problem] To manufacture a unidirectional magnetic steel sheet that improves the iron loss characteristics by irradiating a laser with high positioning accuracy on both the front and back surfaces of a moving steel sheet by a simple apparatus configuration with a reduced number of lasers. Provide equipment. A laser device that outputs laser beams having the same output value from both of two resonator mirrors, and a pair of laser light irradiation devices that simultaneously scan and irradiate the respective laser beams to opposing positions on the front and back surfaces are provided. This is an apparatus for manufacturing a grain-oriented electrical steel sheet having excellent magnetic properties.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for continuously manufacturing a grain-oriented electrical steel sheet whose magnetic properties are improved by laser irradiation.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 58-26405 discloses a method for manufacturing a grain-oriented electrical steel sheet by forming a 180.degree. Magnetic domain wall by irradiating a laser to the steel sheet surface, subdividing magnetic domains, and reducing iron loss. It has been disclosed. In this method, a coating on a steel sheet is evaporated by laser irradiation, and a distortion is given to the surface layer of the steel sheet by an evaporation reaction force to form a reflux magnetic domain in the vicinity thereof. The magnetic domains are subdivided so as to minimize the magnetostatic energy that is increased by the newly created return magnetic domains, and as a result, iron loss is reduced. The iron loss value obtained here is reduced to near the minimum value determined by the degree of integration of the crystal orientation of the material, and it does not involve physical deformation that greatly hinders the magnetic flux, so that the magnetic flux density after laser irradiation hardly decreases. Absent. Therefore, the grain-oriented electrical steel sheet manufactured by this method is the most ideal magnetic property. However, since the strain which is the source of the magnetic domain segmentation disappears by the heat treatment at about 500 ° C. or more, the effect of reducing iron loss disappears in that case. Therefore, since it cannot withstand the strain relief annealing at about 800 ° C performed in the manufacturing process of the wound iron core, the grain-oriented electrical steel sheet manufactured by this method cannot be used for the wound iron core, and It is a core-only material.

On the other hand, as a magnetic domain segmentation technique that can withstand strain relief annealing, a method of forming portions having different magnetic permeability in a magnetic field application direction has been devised. Therefore, various methods and products have been proposed for forming regions having different magnetic permeability in the form of lines or dots on a steel sheet surface in a direction substantially perpendicular to the rolling direction. Above all, a magnetic domain segmentation technology that forms a groove in a surface layer of a steel sheet and utilizes a difference in magnetic permeability between a base material and air has already been industrialized. As a method of forming the groove, a method of mechanically pressing a tooth mold against a steel plate (Japanese Patent Publication No. 63-44804), a method of chemical etching (US Pat. No. 4,750,949), or a processing method using a pulse laser ( JP-A-7-220913). Among them, the groove processing technology using a pulse laser is advantageous in that it is suitable for a high-speed process and has excellent controllability since it is a non-contact processing.

[0004] As described above, the laser method is a method for improving iron loss of a grain-oriented electrical steel sheet which can be applied to both magnetic domain refining techniques for applying strain and forming grooves. Among the laser methods, JP 2000
As disclosed in Japanese Patent No. -109961, the steel sheet having grooves formed in pairs at the front and back surfaces of the steel sheet requires less groove depth to improve iron loss, and as a result, steel sheet deformation that is likely to occur in deep groove processing This is an excellent production method in practical use, for example, there is little. Also, the double-sided irradiation method can be applied to a method for improving iron loss, in which the surface of a steel sheet is subjected to laser irradiation to impart distortion.

[0005] In a method for improving the core loss by performing laser grooving on both surfaces of a steel plate, it is desirable that the deviation of the groove forming position on the front and back surfaces is within about the groove width. This is because a synergistic effect of the magnetic domain refining effect from each surface can be expected. In addition, in this case, there is an advantage that the undulating deformation generated by the laser processing is canceled by the double-sided processing, and excellent flatness can be obtained. Since the width of the groove is about 50 to 300 μm, it is necessary to suppress the displacement amount within this range.

As shown in FIG. 1, in a continuous production facility for electromagnetic steel sheets, the steel sheet 10 moves in the rolling direction (L direction) at a speed of about 50 to 200 m / min. The laser processing according to the present invention scans and irradiates a laser beam on a steel sheet moving at such a high speed in a direction (direction C) substantially perpendicular to the moving direction, and performs the irradiation on both front and back surfaces. The width of a steel sheet is generally about 1 m, but it is practically difficult to perform high-speed scanning with a single laser beam over such a wide width on a steel sheet moving at 50 to 200 m / min. Therefore, it is desirable that the laser beam is divided into a plurality of channels as shown in FIG. Since the scan width per channel is about 50 to 200 mm, about 1
The number of channel divisions for processing the full width of m steel plate is 5 to 2
It will be around 0.

As a method of irradiating both surfaces in each irradiation channel, as shown in FIG. 4, a laser beam from one laser device 1 is time-divided by a rotary chopper 7 and each divided beam is distributed to the front and back surfaces. There is a beam time division method. In this method, in order to match the groove formation position on the front and back surfaces, it is necessary to precisely adjust the beam splitting timing by the chopper and the moving speed of the steel sheet in the rolling direction. That is, the groove A processed on the surface at the upstream of the steel sheet moving direction.
It is necessary to distribute and irradiate the beam to the groove forming position B by the chopper in accordance with the time when the beam has moved downstream.
This method is possible in principle, but it should be put to practical use because the moving speed of the steel sheet in the rolling direction or the rotating speed of the chopper changes for some reason, and if the time relationship between them fluctuates, the groove formation position will be significantly shifted. Was difficult.

[0008] A simultaneous processing method for simultaneously processing both front and back surfaces without beam time division is a method using two laser devices as shown in FIG. 2 or a semi-transmissive mirror as shown in FIG.
A method of dividing the output beam from one laser into two by using 6 can be considered. Here, an irradiation device for only one channel when the entire width of the steel sheet is divided into a plurality of channels is illustrated, and other channels are omitted. In these simultaneous irradiation methods, the positioning accuracy is determined only by the installation position accuracy of the irradiation device composed of a condensing lens and a mirror, so positioning can be performed with a high accuracy of about 10 μm. Since the irradiation is performed simultaneously, the same position processing on the front and back surfaces is always possible regardless of the change in the line speed of the steel sheet.

However, the method of FIG. 2 requires two laser devices for each irradiation channel. In this case, the average laser output per unit is half that required by the method of FIG. 3 and the total laser output is the same, but the number of laser units is doubled. By the way, in order to stabilize the output and beam quality of the high-power laser device for a long period of time, it is necessary to periodically maintain and replace the laser resonator mirror. In particular, when the resonator mirror is replaced, precise adjustment of the mirror angle is required. This must be performed for each laser resonator, and when the number of lasers used increases, the load of maintenance work increases significantly. According to the technology for processing the surface of an electromagnetic steel sheet according to the present invention, as described above, 5 to 20 channels are required to scan the entire width of the steel sheet of about 1 m. Therefore, two laser devices are arranged in each channel. In that case, as many as 10 to 40 laser devices were required. Therefore, it has been desired to reduce the number of lasers required for each channel.

On the other hand, in the method using the semi-transmissive mirror 6 shown in FIG. 3, an output P0 is obtained, which is bisected into P1 and P2 for use. In this case, although the laser output per unit increases and the size of the apparatus increases, the required number of lasers decreases, so that the frequency of maintenance work and the equipment can be simplified. However, the durability of the output split mirror 6 required for splitting the high-power laser beam is low, and the service life is significantly shortened especially in an output region where the average output exceeds 1 kW required for groove processing. There is.

[0011]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, an object of the present invention is to provide a simple apparatus configuration in which the number of lasers is reduced to achieve high positioning accuracy on both the front and back surfaces of a moving steel plate. It is an object of the present invention to provide an apparatus for manufacturing a grain-oriented electrical steel sheet that performs laser irradiation by using the same and improves iron loss characteristics.

[0012]

SUMMARY OF THE INVENTION According to the present invention, a laser beam is scanned and radiated on both the front and back surfaces of a steel sheet moving in the rolling direction in a direction substantially perpendicular to the rolling direction, and a linear or dot is formed at a paired position on the front and back surfaces. In a continuous manufacturing apparatus for unidirectional magnetic steel sheets that form a line-shaped distortion, or groove, or heat-affected layer and improve iron loss characteristics, the same laser output is output from both resonator mirrors at the resonator end. An apparatus for manufacturing a grain-oriented electrical steel sheet having excellent magnetic characteristics, comprising: a laser device to be obtained; and a pair of laser light irradiation devices for simultaneously scanning and irradiating respective laser beams to opposing positions on the front and back surfaces. As a result, the present invention provides a unidirectional magnetic steel sheet manufacturing apparatus capable of irradiating a pair of front and back surfaces of a steel sheet moving in the rolling direction at a high speed with a laser with high positioning accuracy and reducing the required number of lasers by half.

[0013]

Embodiments of the present invention will be described below. First, a laser device that outputs two beams simultaneously will be described. The laser device 1 shown in FIG. 2 is a general CO ₂ laser device that obtains one laser beam from one laser device. The laser resonator is generally composed of a total reflection mirror 3 and a semi-transmissive mirror 2 as shown in FIG.
0 is taken out.

FIG. 1 is an explanatory view of the present invention, and shows a laser device capable of simultaneously outputting two beams. In the laser device 1 used in the present invention, the laser outputs P1 and P2 are taken out from both ends of the resonator by replacing the total reflection mirror 3 of the same laser device as in FIG.
Further, as shown in FIG. 3, the reflectance of the semi-transmissive mirror of the laser resonator for taking out the laser output from one of the resonators is R0.
Assuming that the reflectances of the two semi-transmissive mirrors in FIG. 1 are the same value, R1, R0 and R1 satisfy the following equation (1). Since the total amount of laser output transmitted through the transmission mirror and taken out of the resonator is the same, and the reflectances of the two semi-transmission mirrors are the same R1, the respective outputs P1, P2 as shown in equation (2). P2 has the same value, and therefore has a value half that of P0. R0 = R1 ² ... (1) P0 = 2.P1 = 2.P2 (P1 = P2)... (2) When processing a groove with a pulse laser, use The use of the device also has an advantage that a pulse beam of the same output, whose oscillation timing is completely matched, can be obtained.

Further, as shown in FIG. 1, the two beams output simultaneously are transmitted to the front and back surfaces of the magnetic steel sheet, respectively.
The light is incident on a pair of scan irradiators placed at opposite positions on the front and back surfaces. Each beam is linearly scanned on the steel plate surface,
In addition, the scanning device is a polygon mirror for condensing irradiation
8 and the fθ lens 9. Further, the rotation speed and phase between the polygon mirrors of the scanning device are controlled so that the beam scan positions coincide on the front and back surfaces.

[0016]

Examples of the present invention will be described below. The device configuration is shown in FIG. In the embodiment of the present invention, CO is used as the laser device.
_Two lasers were used. Here, when the laser beam is extracted from only one of the resonators, the average output P0 is 2 kW,
In this case, the configuration of the resonator mirror is a total reflection mirror and a reflection R0 =
It is a 0.5 (50%) transflective mirror. The resonator mirrors of this device were both replaced by two transflective mirrors 2 with reflectivity R1 = 0.7 (70%). As a result, at a frequency of 50 kHz,
A laser output having an average output P1 = P2 = 1 kW was obtained from each semi-transmissive mirror.

Each laser beam is simultaneously transmitted to the scanning irradiation devices installed on the front and back surfaces of the steel plate. Further, the transmission beam is scanned in the plate width direction C by a rotating polygon mirror 8 whose rotation speed and phase are controlled, and an fθ lens having a focal length of 60 mm.
The light is focused at 9. Scan speed in C direction on steel plate is 1
0 m / s and the scan width is 50 mm. The irradiation positions are arranged so as to form a pair on the front and back surfaces, and the positioning accuracy is within ± 20 μm. The steel sheet is about 100m /
It is moving continuously at the speed of minutes. The speed fluctuation is ± 5
%.

With this apparatus configuration, linear grooves were continuously formed on the front and back surfaces of the steel sheet by scanning irradiation with a laser beam.
As a result, irrespective of the fluctuation of the moving speed of the steel sheet, the deviation of the groove forming position on the front and back surfaces in the rolling direction was within ± 20 μm.

[0019]

According to the present invention, the laser beam can be simultaneously transmitted from the single laser device to the front and back surfaces of the steel plate, so that the number of lasers is reduced by half compared to the case where the front and back surfaces are processed by two independent laser devices. It has the advantage of being able to. Further, there is no need to use an output split mirror for a high-power laser having a problem in durability. Further, in the present invention, since the two pulse beams are output and transmitted at the same time, laser irradiation can be performed on the front and back surfaces simultaneously. Therefore, regardless of the movement speed fluctuation of the steel sheet, it is possible to stably process the same position on the front and back surfaces, and as a result, a continuous production method of a unidirectional magnetic steel sheet in which both surfaces are irradiated with laser to improve iron loss characteristics. In this case, it is possible to provide a manufacturing apparatus that always obtains a high iron loss improvement effect stably.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an apparatus for manufacturing a unidirectional magnetic steel sheet that irradiates laser light to both surfaces according to the present invention.

FIG. 2 is an explanatory view of a conventional apparatus for manufacturing a unidirectional magnetic steel sheet that irradiates laser light to both surfaces, and is an explanatory view of an apparatus that processes each surface with two independent laser devices.

FIG. 3 is an explanatory view of a conventional apparatus for manufacturing a unidirectional magnetic steel sheet that irradiates laser light to both surfaces, and is an explanatory view of an apparatus for processing each surface by dividing a laser output into two parts.

FIG. 4 is an explanatory view of a conventional apparatus for manufacturing a unidirectional magnetic steel sheet that irradiates laser light to both sides, and is an explanatory view of an apparatus for processing each surface by temporally dividing a laser output into two parts.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 laser device 2 partial reflection mirror at laser resonator end 3 total reflection mirror at laser resonator end 4 total beam reflection mirror in laser resonator 5 total reflection mirror for beam transmission 6 laser output split half Transmission mirror 7 Laser beam time-division rotating chopper 8 Beam scanning polygon mirror 9 fθ lens 10 Unidirectional magnetic steel sheet R0, R1 Partial reflection mirror reflectance of laser resonator P0, P1, P2 Laser output C Sheet width direction: Beam scanning direction L Rolling direction: Moving direction of steel sheet A, B: Laser irradiation position on steel sheet

Claims (1)

[Claims] 1. A laser beam is scan-irradiated on both the front and back surfaces of a steel sheet moving in the rolling direction in a direction substantially perpendicular to the rolling direction, and linear or dot-shaped distortions, grooves or grooves are formed on the front and back surfaces in pairs. Alternatively, in a continuous manufacturing apparatus for a grain-oriented electrical steel sheet that forms a heat-affected layer and improves iron loss characteristics, a laser device that obtains the same laser output from both of two resonator mirrors at a resonator end, and a laser device for each laser. An apparatus for manufacturing a grain-oriented electrical steel sheet having excellent magnetic properties, comprising a pair of laser light irradiation devices for simultaneously scanning and irradiating a beam on opposite positions on the front and back surfaces.