Laser processing device and laser processing method

Abstract

Disclosed herein is a technique for performing laser processing on a surface of a conveyed workpiece. One aspect of the present disclosure provides a laser processing device that processes the surface of a workpiece by irradiation with laser light, the laser processing device including: an output device that outputs laser light; a light condensing device that condenses the laser light into a prescribed light condensing shape; and a deflection device that moves the condensed laser light irradiation position on the surface of the workpiece at the same movement speed as the conveyance speed of the workpiece conveyed in a first direction by the conveyance device.

Description

[Technical Field]

[0001] The present disclosure relates to a laser processing apparatus and a laser processing method. [Background technology]

[0002] The manufacturing process for grain-oriented electrical steel sheets mainly consists of hot rolling, cold rolling, primary recrystallization (decarburization) annealing, secondary recrystallization (finish) annealing, flattening annealing, and coating. During this manufacturing process, a magnetic domain control technology has been put into practical use to reduce iron loss by applying linear thermal strain at regular intervals in a direction approximately perpendicular to the rolling direction, i.e., in the sheet width direction, to the surface of the grain-oriented electrical steel sheet after the coating process as the steel sheet is transported in the rolling direction (Patent Document 1). Another method for improving iron loss by forming grooves by laser irradiation has also been disclosed (Patent Document 2).

[0003] Furthermore, a technology has been disclosed in which localized heated regions are formed by irradiating an electrical steel sheet after cold rolling and before finish annealing with a laser in a direction approximately parallel to the sheet width direction, thereby generating grain boundaries in the regions after finish annealing, thereby improving magnetic properties such as reducing iron loss and increasing magnetic flux density (Patent Document 3).

[0004] In these techniques, a laser beam focused in a thin line, circle, or ellipse in the rolling direction L is projected onto the surface of a steel sheet transported in the rolling direction L at a transport speed VL, and then projected in the sheet width direction C approximately parallel to the rolling direction at a speed V C Here, the laser power is P [W], the focused light shape is an ellipse, the major axis diameter in the scanning direction is Dc, and the minor axis diameter in the perpendicular direction is D L Then, as expressed by equations (1) and (2), Dc and D L The light collecting area, which is the product of 2 ], where I is the power density P [W / mm 2 ] is I P = P / S. Since Ip represents the energy input per unit time, the higher the Ip, the faster the heating rate.

[0005] Furthermore, to achieve certain effects by heating steel sheets, such as distortion, deep groove processing, and grain boundary formation, it is necessary to reach a required temperature, i.e., a certain irradiation time is required even at a high Ip. In a method of irradiating by scanning a laser in the sheet width direction, the irradiation time Tt at the point where the laser light passes is expressed as Tt = Dc / Vc, as shown in the following equation (3), where Vc is the scanning speed. To increase Tt, Dc must be increased or Vc must be decreased. Here, from the viewpoint of productivity, decreasing Vc is disadvantageous, so to increase Tt, the focused beam diameter Dc in the scanning direction must be increased.

[0006] S=(π / 4) D L D C [mm 2 ] (1) I P =P / S=(4 / π)·P / (D L D C ) [W / mm 2 ] (2) T t =D C / V C [sec] (3)

[0007] Therefore, in order to efficiently form a linear heating area by scanning laser light in the plate width direction at high speed on a steel plate moving in the rolling direction, it is desirable to focus the light in a line that is long in the scanning direction and thin in the direction perpendicular to that direction.

[0008] The laser beam having such a long focused shape in the width direction of the plate is scanned in the width direction of the plate to form an elliptical (or linear) focused beam with a minor axis diameter D L As a method for forming a thin heating area equivalent to the above, Patent Document 1 describes a method for forming a thin heating area equivalent to the above, in which the conveying speed of the steel plate is V L and the scanning speed of the laser beam V C Therefore, a technique is described in which an inclination angle, which is the angle between the scanning direction of the laser light and the major axis of the focused shape, is calculated and set. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 5135542 [Patent Document 2] Patent No. 5234222 [Patent Document 3] Patent No. 4782248 Summary of the Invention [Problem to be solved by the invention]

[0010] However, as in the method of Patent Document 1, the minor axis diameter D of the elliptical (or linear) focusing L Compared with the plate width direction focused diameter D C In the case of a linear focused beam shape where the beam width is extremely long, the angle must be set very precisely. In other words, if the angle is not set precisely, the width of the heating area in the rolling direction will increase. As a result, the I p This causes a problem that the heating required for thermal distortion and grain boundary formation cannot be achieved. For example, the minor axis diameter D L =0.1mm and the beam diameter in the plate width direction D C When a thin elliptical beam with a diameter of 50 mm is scanned parallel to the width direction of the plate, the width of the heating area in the rolling direction is L However, if the actual setting angle is off by 0.1 degrees, the width of the heating area in the actual rolling direction L becomes about 0.2 mm, which is about twice the width of the target heating area, i.e., I p will be halved.

[0011] In view of the above problems, an object of the present disclosure is to provide a technique for performing laser processing on the surface of a transported workpiece. [Means for solving the problem]

[0012] In order to solve the above problem, according to one aspect of the present disclosure, there is provided a laser processing apparatus that processes the surface of a workpiece by irradiating it with laser light, the laser processing apparatus having an output device that outputs laser light, a focusing device that focuses the laser light into a predetermined focusing shape, and a deflection device that moves the irradiation position of the focused laser light on the surface of the workpiece at a moving speed that is the same as the conveying speed of the workpiece being conveyed in a first direction by a conveying device.

[0013] In addition, in order to solve the above-mentioned problems, according to another aspect of the present disclosure, there is provided a laser processing method for processing the surface of an object to be processed by irradiating laser light, the laser processing method including a focusing step of focusing the laser light on the object to be processed while the object is being transported at a predetermined transport speed in a first direction, and a moving step of moving the irradiation position of the focused laser light on the surface of the object to be processed at a moving speed that is the same as the transport speed in the first direction. [Effects of the Invention]

[0014] According to the present invention, the focused shape of the laser beam on the workpiece moves in the conveying direction of the workpiece at the same moving speed as the conveying speed. Conventionally, the focused shape of the laser beam moves in a direction approximately perpendicular to the conveying direction, but according to the present invention, a technology for laser processing the surface of a conveyed workpiece can be provided. Therefore, it is possible to stably perform thin or minute localized heating processing by irradiating the surface of a moving workpiece with a laser, as typified by a magnetic domain control process for electromagnetic steel sheets, for example. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram of an example of a laser processing device according to an embodiment of the present invention, viewed from the Z direction (vertical direction). [Figure 2] FIG. 2 is a schematic view of an example of a laser processing device according to an embodiment of the present invention, viewed from the arrow C direction. [Figure 3]FIG. 3 is a schematic view of an example of a laser processing device according to an embodiment of the present invention, viewed from the arrow L direction. [Figure 4] FIG. 4 is a schematic diagram of a heating region according to an embodiment of the present invention. [Figure 5] FIG. 5 is a schematic diagram showing an example of a laser processing device according to an embodiment of the present invention. [Figure 6] FIG. 6 is a schematic diagram showing an example of a laser beam deflected by a polygon mirror according to an embodiment of the present invention. [Figure 7] FIG. 7 is a schematic view of another example of a laser processing device according to an embodiment of the present invention, viewed from the arrow C direction. [Figure 8] FIG. 8 is a schematic view of another example of the laser processing device according to the embodiment of the present invention, viewed from the arrow C direction. [Figure 9] FIG. 9 is a schematic diagram showing another example of laser light deflected by a polygon mirror according to an embodiment of the present invention. [Figure 10] FIG. 10 is a schematic view of another example of a laser processing device according to an embodiment of the present invention, viewed from the arrow C direction. [Figure 11] FIG. 11 is a flow chart showing a laser processing method according to an embodiment of the present invention. [Figure 12] FIG. 12 is a diagram illustrating laser illumination parameters and polygon mirror parameters for various embodiments of the present disclosure. [Figure 13] FIG. 13 is a schematic view of another example of the laser processing device according to the embodiment of the present invention, viewed from the arrow C direction. [Figure 14] FIG. 14 is a schematic view of another example of a laser processing device according to an embodiment of the present invention, viewed from the arrow C direction. [Figure 15] FIG. 15 is a schematic view of another example of a laser processing device according to an embodiment of the present invention, viewed from the arrow C direction. [Figure 16] FIG. 16 is a schematic diagram of an example of an optical path switching device according to an embodiment of the present invention. [Figure 17] FIG. 17 is a schematic view of another example of a laser processing device according to an embodiment of the present invention, viewed from the arrow C direction. [Figure 18] FIG. 18 is a schematic view of another example of a laser processing device according to an embodiment of the present invention, viewed from the arrow C direction. [Figure 19] FIG. 19 is a schematic view of another example of a laser processing device according to an embodiment of the present invention, viewed from the arrow C direction. [Figure 20] FIG. 20 is a schematic diagram showing two or more laser processing devices according to an embodiment of the present invention arranged in the width direction of a plate. [Figure 21] FIG. 21 is a schematic diagram showing another example of the laser processing device according to the embodiment of the present invention. [Figure 22] FIG. 22 is a schematic diagram of another example of a heating region according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the case of introducing thermal strain to control the magnetic domains of a grain-oriented electrical steel sheet will be described as an example. The present invention can also be applied to other cases where a transported workpiece is thermally processed by irradiating it with a laser, even if the purpose is different, such as melting to excavate a groove or drilling a hole to penetrate the area. Melting and drilling are achieved by adjusting at least one of the energy density and irradiation time in the thermal processing. In this specification and drawings, components having substantially the same functional configuration are designated by the same reference numerals, and redundant explanations will be omitted.

[0017] [Laser processing equipment] 1 to 3 show a laser processing apparatus 100 according to an embodiment of the present invention. FIG. 1 is a view of the laser processing apparatus 100 as seen from above in the vertical direction, and FIG. 2 is a view of the laser processing apparatus 100 as seen from the sheet width direction C. FIG. 3 is a view of the laser processing apparatus 100 as seen from the conveyance direction L of the grain-oriented electrical steel sheet 10. The laser processing apparatus 100 according to the embodiment of the present invention thermally processes the surface of the grain-oriented electrical steel sheet 10, thereby forming linear grooves or linear thermal distortions extending in an extension direction of the grain-oriented electrical steel sheet 10, which is a direction substantially parallel to the sheet width direction C. As shown in the figures, the laser processing apparatus 100 includes a conveyance device 110, an output device 120, a focusing device 130, and a polygon mirror 140. Note that in the following examples, the laser processing apparatus 100 processes the surface of the grain-oriented electrical steel sheet 10, but the laser processing apparatus 100 according to the present disclosure is not necessarily limited to this and may process any other workpiece.

[0018] The conveying device 110 conveys the grain-oriented electrical steel sheet 10 in a conveying direction L perpendicular to the sheet width direction C at a predetermined conveying speed V L For example, the conveying device 110 includes a plurality of rollers for moving the grain-oriented electrical steel sheet 10 in the conveying direction L, and by rotating the rollers in the conveying direction L, the grain-oriented electrical steel sheet 10 placed on the rollers is conveyed at a predetermined conveying speed V L The sheet is moved in the conveying direction L. The conveying direction L is the same as the rolling direction of the rolled steel sheet. The sheet width direction C is the direction perpendicular to the rolling direction of the steel sheet.

[0019] The output device 120 is a device that outputs laser light 20. Specifically, it may be a fiber laser, YAG laser, CO2 laser, or the like, and the type of laser is not particularly important as long as it is a laser used for processing. The output laser light 20 propagates toward the focusing device 130 and the polygon mirror 140.

[0020] The focusing device 130 is provided as a single or multiple components on the optical path from the output device 120 to the grain-oriented electrical steel sheet 10. The focusing device 130 focuses the input laser beam 20 into a predetermined focused shape and outputs the focused beam. Specifically, the focusing device 130 focuses the laser beam 20 on the surface of the grain-oriented electrical steel sheet 10 into a shape that is long in one direction and short in another direction perpendicular to the first direction, such as a substantially linear ellipse as shown in FIG. 4 . The predetermined focused shape is formed so that the extension direction of the linear grooves or linear thermal distortions to be formed coincides with the first direction. For example, the focusing device 130 is rotated about the laser optical axis E to align the extension direction of the grooves or linear thermal distortions with the first direction. In order to reduce iron loss, the linear grooves or linear distortions are set to extend in a direction perpendicular to the conveyance direction (sheet width direction C) or in a direction within 45 degrees from the sheet width direction C (0 degrees≦substantially parallel≦45 degrees) in a plane parallel to the steel sheet surface. For the grain-oriented electrical steel sheet 10, the direction in which the linear grooves or linear strains extend may be at an angle of 0 degrees or more and 10 degrees or less with respect to the sheet width direction C.

[0021] The focused beam shape can be adjusted using the focusing device 130. That is, the focusing device 130 may form the laser beam 20 in a focused beam shape that is short in a first direction and long in a second direction perpendicular to the first direction. For example, in the example shown in FIGS. 1 and 2 , the focusing device 130 adjusts the focused beam diameter in the sheet width direction C of the grain-oriented electrical steel sheet 10 to a sheet width direction focused beam diameter D C (i.e., the length of the diameter passing through the intersection of the major axis and the minor axis and parallel to the conveyance direction L), and L 4, the focused shape of the laser beam 20 is D L <D C Specifically, the diameter of the focused beam in the width direction of the plate D C To set the length of the laser beam 20 to an arbitrary length, a concave lens may be used as the lens 131 to expand the diameter of the laser beam 20, and the distance between the lens 131 and the steel plate may be adjusted to set Dc to a desired value. LRegarding the lens 132, a convex lens is used, and the position of the lens 132 is adjusted so that the focal position of the lens 132 coincides with the surface of the steel sheet. L may be set to a desired value. Here, Fig. 5 is a schematic diagram of laser beam 20 deflected by polygon mirror 140 according to an embodiment of the present invention. More specifically, Fig. 5 shows a schematic diagram of laser beam 20 deflected by polygon mirror 140 according to an embodiment of the present invention. Note that Fig. 4 is an enlarged view of a portion of the electromagnetic steel sheet shown in B of Fig. 5, viewed from above in the vertical direction.

[0022] The polygon mirror 140 has a plurality of reflecting surfaces and is rotatable about a rotation axis that is parallel to the steel sheet surface and perpendicular to the conveyance direction of the workpiece, specifically, the grain-oriented electrical steel sheet 10 in this embodiment. The polygon mirror 140 may also be configured to rotate at a rotation speed corresponding to the movement speed of the irradiation position. The rotation axis is rotatably supported by a support device (not shown) so that it rotates in a direction that allows the laser beam 20 incident from one direction to be deflected and moved in the conveyance direction L by reflection on each reflecting surface of the polygon mirror 140. In other words, as each reflecting surface rotates around the rotation axis RX, the angle of incidence of the laser beam 20 changes sequentially within each reflecting surface, and the irradiation position of the laser beam 20 on the surface of the grain-oriented electrical steel sheet 10 can be moved at a movement speed V that corresponds to the rotation speed. C The polygon mirror 140 moves in the same direction and at the same speed as the transport direction L. When it changes to the next reflective surface, the incident angle returns to the initial angle, and the irradiation position returns to upstream in the transport direction L. This is repeated as many times as the number of reflective surfaces while the polygon mirror 140 makes one rotation.

[0023] Below, using Figure 6, the irradiation interval P L 6 shows the laser beam 20 reflected and deflected by the polygon mirror and the conveyance direction irradiation interval P L2. FIG. 6 is an enlarged view of the portion indicated by A in FIG. 2. Focusing on one surface of the polygon mirror 140, consider the case where the laser beam 20 is reflected by that surface. When the polygon mirror 140 is viewed from the sheet width direction C, the boundary between the one surface and the surface ahead of the one surface in the rotation direction is designated as vertex A', and the boundary between the one surface and the surface behind the one surface in the rotation direction is designated as vertex B'. When the laser beam 20 is reflected by vertex A', the position on the steel sheet where the reflected laser beam 20 is irradiated is designated as irradiation position I, and when the laser beam 20 is reflected by vertex B', the position on the steel sheet where the reflected laser beam 20 is irradiated is designated as irradiation position II. As the polygon mirror 140 rotates, the reflection point R where the laser beam 20 is reflected moves from vertex A' to vertex B' of the polygon mirror 140. As a result, the laser beam 20 moves from irradiation position I on the surface of the grain-oriented electrical steel sheet 10 to irradiation position II on the surface of the grain-oriented electrical steel sheet 10. Immediately after the laser beam 20 is irradiated onto the vertex B', the laser beam 20 is reflected by the vertex A' on the (next) face behind the given face in the rotation direction, and the reflected laser beam 20 is again irradiated onto the irradiation position I, and this operation is repeated. The moving distance from the irradiation position I to the irradiation position II on the surface of the grain-oriented electrical steel sheet 10 is called the laser irradiation interval P L Then, the rotation of the polygon mirror 140 causes the steel plate to move in the conveying direction P L The thermally processed areas are formed by laser irradiation at intervals of .

[0024] Here, the number of faces of the polygon mirror is N p , the central angle of each mirror surface is θ P This gives the following relationship: θ P =360 / N p (4) where θ P corresponds to half the deflection angle of the laser beam 20 due to the polygon mirror reflection, so P L If the distance of the perpendicular line from the reflection point R of the polygon mirror to the steel plate surface is h, then P L is expressed as equation (5). P L =2·h·tanθ P (5)

[0025] Furthermore, in the present invention, the moving speed V of the irradiation point of the laser beam 20 by the polygon mirror 140 (for example, a specific position such as the center position between the start point and the end point of the laser beam irradiation position due to the deflection of the laser beam 20 caused by the change in the reflection angle of one mirror due to the rotation of the polygon mirror 140) on the grain-oriented electrical steel sheet 10 C and the conveying speed V of the grain-oriented electrical steel sheet 10 by the conveying device 110. L As a result, the focused shape of the laser beam 20 advances in the conveying direction L so as to follow the same region on the grain-oriented electrical steel sheet 10 being conveyed, so that the laser beam 20 can be continuously irradiated onto the same region on the surface of the grain-oriented electrical steel sheet 10.

[0026] For example, the direction of reflection is deflected by the rotation of the polygon mirror 140, and the irradiation point of the laser light 20 is set to P L When the polygon mirror 140 is moved at a constant speed, the distance between the reflection point R of the polygon mirror 140 and the grain-oriented electrical steel sheet 10 changes from he at the start point (irradiation position I) of the movement to h at the center point O of the movement, and then changes to he at the end point (irradiation position II). Therefore, even if the rotation speed of the polygon mirror 140 is constant, the movement speed of the irradiation point on the steel sheet changes slightly. Specifically, the speed at the center point O of the movement is V C Then, the velocity V at the start and end points of the movement Ce is as follows. V Ce =(he / h) V C (6)

[0027] That is, the speed of movement of the irradiation shape due to the rotation of one reflecting surface of the polygon mirror 140 slows down from the start point to the center point O, and increases from the center point O to the end point. In the present invention, for example, as described above, the rotation of the polygon mirror 140 causes the deflection of the laser beam 20 due to the change in the reflection angle of one mirror, and the moving speed at the center point O (hereinafter, also referred to as the irradiation position) of the start point and the end point of the laser beam irradiation position is defined as the moving speed V cTherefore, within the time it takes for the laser beam 20 to be reflected on one of the reflecting surfaces of the polygon mirror 140, the speed changes between the start point of the movement, the center point O of the irradiation, and the end point of the movement, so the conveying speed V of the grain-oriented electrical steel sheet 10 L If is constant, a discrepancy will occur between the transport speed L of the grain-oriented electrical steel sheet 10 and the moving speed of the irradiation position during the movement of the irradiation point. As a result, the effective focused shape on the grain-oriented electrical steel sheet 10 will change, i.e., the power density will change. While it is preferable that the moving speed and the transport speed are perfectly consistent, some degree of change in power density caused by such a speed discrepancy is acceptable depending on the processing purpose. For example, if the change in power density is within about 10%, it will not affect thermal distortion or groove processing purposes.

[0028] For example, in the first embodiment described later, the number of polygon faces N p = 38, and the distance between the reflection point and the steel plate h = 30 mm, then he = 30.41 mm, the difference in speed between the start point and the center point of movement is approximately 1%, and the difference in the effective focusing shape between the center point of movement and the start point and end point is also equivalent, so the effect on processing is within a negligible range.

[0029] Furthermore, as shown in Figure 6, when the movement of the laser beam 20 is viewed from the sheet width direction C, the focal point of the laser beam 20 is formed on an arc shown by a dotted line with the reflection point R of the polygon mirror 140 as the center. Therefore, if, for example, h is set so that the focal point is formed at the center point O of the movement, the shape of the focused beam at irradiation positions I and II will, strictly speaking, be different from the shape at the focal point. However, for example, by shortening the distance h between the reflection point R of the polygon mirror 140 and the grain-oriented electrical steel sheet 10, or by appropriately setting the configuration and focal length of the focusing device 130, the deviation of the focused beam shape can be kept within a relatively negligible range. Furthermore, setting h to a short value reduces the aforementioned V c , V ce This also helps to reduce the discrepancy.

[0030] In addition, the change in the light concentration shape on the steel plate surface and the moving speed V C7, by using an Fθ lens 133 as one component of the output device 120 between the reflection point R of the polygon mirror 140 and the grain-oriented electrical steel sheet 10, the focus can be formed along the steel sheet surface regardless of the movement position, and the movement speed can also be made constant. Note that the focusing device 130 may include one or more convex or concave lenses 134 between the polygon mirror 140 and the output device 120 in addition to the Fθ lens 133 to adjust the laser focusing shape.

[0031] Therefore, in the present invention, the laser beam 20 is irradiated onto the surface of the grain-oriented electrical steel sheet 10 at an irradiation interval P in the conveyance direction. L As a result, the irradiation interval in the conveying direction P L The region (hereinafter referred to as the heated region) to which the laser beam 20 continues to be irradiated for the time required for the laser beam 20 to travel forms a linear or dot-like groove or linear distortion having the length of the major axis of the focused shape. The movement of the laser beam 20 repeatedly performed by each reflecting surface of the polygon mirror 140 switches instantaneously from the irradiation position II to the irradiation position I, so the interval at which the linear groove or linear distortion is formed is the irradiation interval P in the conveying direction L. L can be considered to be equal to

[0032] Here, the heated region refers to the region on the surface of the grain-oriented electrical steel sheet 10 that is irradiated with the laser beam 20 in a focused shape.

[0033] 5, the polygon mirror 140 has a polygonal cross section depending on the number of faces, and the center of this cross section is the rotation axis RX. The direction of rotation is the same as the conveyance direction L of the grain-oriented electrical steel sheet 10, in which the deflection direction of the reflected laser light due to rotation. The rotation speed V of the polygon mirror 140 θ [degrees / sec] is the moving distance P of the laser beam 20 moved by the polygon mirror 140. L The moving speed V at the center point O of C is the conveying speed V of the grain-oriented electrical steel sheet 10 L (See Figure 6.) This conveying speed V LRegarding the rotation speed signal of the motor that drives the rollers of the conveying device 100, the motor rotation speed V of the rotary motor of the polygon mirror 140 is input to a control device (not shown) of the rotary motor of the polygon mirror 140. rpm is controlled (for example, by feedback control). The rotation speed of the motor and the rotation speed of the polygon mirror 140 do not necessarily have to be the same, and a rotation speed conversion gear may be inserted between the motor and the polygon mirror 140. In this case, by appropriately setting the gear ratio, the moving speed V of the irradiation position of the laser light can be controlled. C is the moving speed of the workpiece V L The rotation speed of the polygon mirror 140 may be set to match the rotation speed of the polygon mirror 140.

[0034] In this way, according to the present embodiment, the focused shape formed on the surface of the grain-oriented electrical steel sheet 10 by adjusting using the focusing device 130 is maintained substantially constant, while the irradiation position moves in the conveying direction L in accordance with the conveyance of the grain-oriented electrical steel sheet 10. As a result, the irradiation time T t During the period, the power density I P The laser beam 20 can be irradiated at the irradiation position on the grain-oriented electrical steel sheet 10 while maintaining the desired value. In this way, by moving the focused shape of the laser beam 20 having the major axis in the conveying direction L so as to follow the same area on the steel sheet being conveyed, fine adjustment of the inclination angle, which is required in the conventional case of moving the steel sheet approximately parallel to the sheet width direction C, is no longer necessary, and the laser can be irradiated appropriately onto the workpiece.

[0035] When the present invention is applied to the manufacture of grain-oriented electrical steel sheet 10, the laser irradiation parameters and the design parameters of polygon mirror 140 can be set by the following procedure. The important parameters for appropriately forming linear grooves or linear distortions in grain-oriented electrical steel sheet 10 are power density I p , irradiation time T t , conveying direction irradiation interval P L In the production line for the grain-oriented electrical steel sheet 10, the conveying speed V L is set to a predetermined speed. In addition, the irradiation interval P LThe width of the groove or strain in the rolling direction is preferably small, so it is a parameter that should be determined in advance. L、 Transport direction irradiation interval P L , and the minor axis diameter of the ellipse D L Let be a given fixed parameter.

[0036] Step 1: Laser irradiation parameters The irradiation time T is an important parameter for providing grooves or distortion to the grain-oriented electrical steel sheet 10. t is set by the following equation (7). T t =P L / V L [msec] (7)

[0037] Step 2: Polygon mirror design parameters The central angle θ of each face of the polygon mirror 140 P is determined by the following equation (8): θ P =tan -1 (P L / (2·h))[degrees] (8) Here, h is the distance from the reflection point R of the polygon mirror 140 to the vertically downward surface of the grain-oriented electrical steel sheet 10. Also, h is the number of faces N of the polygon mirror 140. P may be fine-tuned to be an integer. Rotational angular velocity V of polygon mirror 140 θ is determined by the following equation (9): V θ =θ P / (T t / 1000)[degrees / sec] (9) Motor rotation speed V of polygon mirror 140 rpm is determined by the following equation (10): V rpm =(V θ / 360)·60[rpm] (10) Number of faces N of polygon mirror 140 P is determined by the following equation (11): NP =360 / θ P (11)

[0038] The main parameter names, symbols and units used in this specification are summarized in the table below. [Table 1]

[0039] Here, the conveying speed V L While keeping constant, the irradiation interval in the conveying direction P L 8 is a schematic diagram of the laser beam 20 deflected by the polygon mirror 140 according to an embodiment of the present invention, as viewed from the sheet width direction C. FIG. 9 is an enlarged view of a portion A in FIG. 8, showing the laser beam 20 as a representative by its optical axis E. The conveying direction irradiation interval P according to an embodiment of the present invention L A schematic diagram of the conveying speed V L Without changing the irradiation interval in the conveying direction P L When changing the value, the laser power P of the output device 120, the distance h between the reflection point R of the polygon mirror 140 and the grain-oriented electromagnetic steel sheet 10, and the motor rotation speed V of the polygon mirror 140 are used. rpm First, the conveyance direction irradiation interval P L When multiplying by n, as shown in FIG. 9, the distance h is multiplied by n (where n is an arbitrary number greater than 0) to set it to h', and the conveyance direction irradiation interval P L The physical distance is n times P L'. As shown in FIG. 8, when the distance h is multiplied by n, the position of the focusing device 130 is appropriately adjusted in accordance with the movement of the polygon mirror 140 so as to maintain a constant distance from the focusing device 130 to the grain-oriented electromagnetic steel sheet 10 and prevent focus shifting. Here, the focusing device 130 is composed of, for example, a concave lens 131 and a convex lens 132 to focus the laser beam 20 linearly, and the distance between these lenses is maintained. Here, the distance between the focusing device 130 and the grain-oriented electromagnetic steel sheet 10 is, for example, the distance along the optical axis E from the convex lens 132 to the grain-oriented electromagnetic steel sheet 10, and the position of the focusing device 130 is moved so as to maintain this distance when the polygon mirror 140 is moved. In addition, the irradiation interval P in the conveying direction L is L When multiplied by n, the time for which the heating area is continuously irradiated (laser irradiation time T t ) is multiplied by n, but the power density I irradiated to the grain-oriented electrical steel sheet 10 is p In order to keep the distance h constant, the laser power P is set to 1 / n. Furthermore, when the distance h is multiplied by n, the moving speed V of the laser beam 20 C is multiplied by n, so the motor rotation speed V rpm By multiplying by 1 / n, the moving speed V of the laser beam 20 C The conveying speed V L By setting it as above, the conveying speed V L While keeping constant, the irradiation interval P in the conveying direction L L The irradiation interval P in the transport direction L can be changed by a factor of n. L It is also possible to control the magnetic domain control characteristics of the grain-oriented electrical steel sheet by adjusting the P L It is possible to apply it in other ways, such as changing the

[0040] The magnetic domain control characteristics here refer to the rate of change that indicates the degree of change in magnetic properties (for example, iron loss, magnetostriction, magnetic flux density, etc.) that change as a result of magnetic domain control. The change in magnetic properties is determined by the irradiation interval P L , depends on the magnitude of each thermal distortion, the depth of the groove, etc. That is, the deflection device 150 such as the polygon mirror 140 has an irradiation interval PL The function to adjust the irradiation interval P L By adjusting the above, the iron loss, magnetostriction, magnetic flux density, etc. of the grain-oriented electrical steel sheet 10 may be changed.

[0041] 10, a laser irradiation device 100 may include one transport device 110, two output devices 120, two focusing devices 130, and one polygon mirror 140 (deflection device 150), and two laser beams 20 may be incident on the one polygon mirror 140 from opposite directions. As shown in the figure, the two output devices 120 irradiate the laser beams 20 toward the corresponding focusing devices 130. In this case, the interval G between the two laser beams 20 in the movement direction of each irradiation position can be set to satisfy the following formula (12). G=(m+1 / 2)·P L (12) Here, m is an integer equal to or greater than 1. Specifically, a method for setting G so as to satisfy equation (12) is to appropriately adjust the diameter of the polygon mirror 140. According to the embodiment shown in FIG. 10, the irradiation interval of each output device 120 in the transport direction L is set to 2×P L From equation (8), the central angle θ of each surface of the polygon mirror 140 can be calculated. P is doubled, and the number of faces of the polygon mirror 140, N P This has the advantage of reducing the manufacturing cost of the polygon mirror 140 by half, thereby reducing the manufacturing cost of the polygon mirror 140. In addition, the distance h between the polygon mirror reflection point R and the grain-oriented electromagnetic steel sheet 10 also increases, so in the case of groove machining, for example, it is possible to prevent molten material and the like that splashes from the machined portion from adhering to the polygon mirror 140.

[0042] [Laser processing method] Next, a laser processing method according to an embodiment of the present invention will be described using Fig. 11 as an example in which the object to be processed is a grain-oriented electrical steel sheet 10. Fig. 11 is a diagram showing the laser processing method according to an embodiment of the present invention. In the laser processing method shown in Fig. 11, a laser processing apparatus 100 irradiates the surface of the grain-oriented electrical steel sheet 10 with laser light 20 having the above-mentioned elliptically focused shape, thereby forming linear grooves or linear distortions extending in a direction approximately parallel to the sheet width direction C of the grain-oriented electrical steel sheet 10.

[0043] As shown in Fig. 11, the laser processing method includes a focusing step (S103) and a moving step (S104). In the embodiment shown in Fig. 11, the laser processing method further includes a preparation step (S101) and a transport step (S102).

[0044] In step S101, the laser processing apparatus 100 is adjusted. Specifically, using a focusing device 130 provided on the optical path from the output device 120 to the grain-oriented electrical steel sheet 10, the focused shape of the laser beam 20 on the surface of the grain-oriented electrical steel sheet 10 is made into a substantially linear ellipse that is long in one direction and short in another direction perpendicular to the one direction, and one direction of the substantially linear ellipse is made to coincide with a direction substantially parallel to the sheet width direction C.

[0045] In order to reduce iron loss, the linear grooves or linear strains are set to extend in a direction substantially perpendicular to the rolling direction (a direction substantially parallel to the sheet width direction C). Therefore, the one direction is a direction parallel to the extension direction of the linear grooves or linear strains.

[0046] In step S102, the laser processing apparatus 100 uses the conveying device 110 to convey the grain-oriented electrical steel sheet 10, which is the workpiece, in a conveying direction L perpendicular to the sheet width direction C at a predetermined conveying speed V L Transport by.

[0047] In step S103, the laser processing device 100 moves the laser beam in the conveying direction L at a predetermined conveying speed V L At a given conveying speed V LThe laser beam 20 output from the output device 120 is focused on the grain-oriented electrical steel sheet 10 being transported.

[0048] In step S104, the laser processing device 100 adjusts the irradiation position of the focused laser beam 20 on the surface of the grain-oriented electrical steel sheet 10 at a conveying speed V L The same movement speed V C Specifically, the laser processing apparatus 100 uses a deflection device 150 (polygon mirror 140 in this embodiment) to reflect the laser beam 20, thereby irradiating the laser beam 20 onto the surface of the grain-oriented electrical steel sheet 10, and rotates about a rotation axis parallel to the sheet width direction C to change the traveling direction of the laser beam 20, thereby moving the irradiation position of the laser beam 20 on the surface of the grain-oriented electrical steel sheet 10 in the conveying direction L at a predetermined moving speed V C Here, the laser processing device 100 is moved at a conveying speed V L and the moving speed V of the laser beam 20 from the polygon mirror 140 C Specifically, the motor rotation speed V of the rotary motor of the polygon mirror 140 is made to match. rpm is the moving speed V of the laser beam 20. C The conveying speed V of the oriented electrical steel sheet 10 L is controlled to match.

[0049] As described above, the laser processing apparatus 100 and the laser processing method according to the present invention can stably form a thin linear heated region on the surface of the grain-oriented electrical steel sheet 10 regardless of the length in the major axis direction of the focused shape of the laser beam 20. L While keeping constant, the interval of the linear grooves or linear distortions in the conveying direction L (irradiation interval P L ) can be set arbitrarily. That is, the deflection device 150 may have a function to adjust the irradiation interval in the transport direction L.

[0050] Although the example in which one laser processing device 100 is installed has been shown above, it is also possible to install multiple devices in the plate width direction C in accordance with the length of the plate width, and form linear grooves or linear distortions over the entire length in the plate width direction. Furthermore, the present invention also allows two output devices 120 to be installed with polygon mirrors 140 facing each other, and the two laser beams 20 to be moved by the polygon mirror 140. [Example]

[0051] In Examples 1 to 3 described below, when the laser irradiation parameters and polygon mirror design parameters were set to the parameter values ​​shown in Fig. 12, the magnetic characteristics shown in Fig. 12 were obtained. Note that, where the rotation speed Vθ [degrees / sec] of the polygon mirror 140 and the motor rotation speed Vrpm [rpm] of the rotary motor are expressed as Vrpm = Vθ / 360 × 60.

[0052] [Example 1] In the laser processing apparatus and the laser processing method of the present disclosure, the conveying speed V L = 0.5 [m / sec], the grain-oriented electrical steel sheet 10 having a width of 100 [mm] is continuously fed in the conveying direction, which is the rolling direction, with an interval P L Regarding the laser irradiation parameters, a continuous wave fiber laser with a wavelength of 1.06 μm and a laser power of 5000 W was used as the output device 120, and a combined lens of a cylindrical convex lens and a cylindrical concave lens was used as the condenser 130 to condense the material into a linear shape with a width D in the conveying direction. L =0.2 [mm], plate width direction focusing diameter D C = 106.2 [mm], and the power density I P =300[W / mm2], irradiation time T t =20[msec].

[0053] Next, the polygon mirror design parameters are as follows: the number of faces of the polygon mirror 140, N P The surface central angle θ of the polygon mirror 140 in Equation (8) is set to an integer. PIn order to select the above, the vertical distance between the reflection point of the polygon mirror 140 and the grain-oriented electromagnetic steel sheet 10 is set to h=30 [mm], and the surface central angle of the polygon mirror 140 is set to θ P = 9.5[degrees], and the number of faces is N P = 38. The motor rotation speed V of the polygon mirror 140 rpm From equations (9) and (10), V rpm After determining the number of faces of the polygon mirror 140 from the above, h and V rpm By fine-tuning V c and V L were matched.

[0054] The grain-oriented electrical steel sheets 10 were subjected to continuous laser irradiation under the above conditions, and then decarburization annealing, finish annealing, flattening annealing, and coating processes. Thirty grain-oriented electrical steel sheets 10, each 300 mm long in the conveying direction and 60 mm long in the sheet width direction, were sampled and their magnetic properties were evaluated. The magnetic properties were measured by measuring the iron loss W in an alternating magnetic field with a magnetic flux density of 1.7 T and a frequency of 50 Hz. 17 / 50 The magnetic flux density B8 generated in a magnetic field of 0.8 [A / m] was measured. 17 / 50 The smaller the B8 and the higher the magnetic flux density B8, the better the magnetic properties. Since there is a trade-off between the reduction in iron loss and the improvement in magnetic flux density due to thermal processing, in the grain-oriented electrical steel sheet 10 of Example 1, the magnetic flux density B8 was reduced by 0.02 [T] compared to the non-laser irradiated portion, but the iron loss W 17 / 50 =0.753 [W / kg], which means that the iron loss was reduced by approximately 10%. Therefore, according to Example 1, it is possible to provide a material suitable for transformers that place importance on iron loss.

[0055] [Example 2] In Example 2, based on the embodiment described above with reference to FIGS. 8 and 9, the conveying speed V L is kept constant, and the irradiation interval P L is expanded from 10 [mm] to 15 [mm], and the irradiation interval in the conveying direction P LBased on the magnification of 1.5 times, the laser power P is set to 1 / 1.5, the distance h between the reflecting surface of the polygon mirror 140 and the grain-oriented electromagnetic steel sheet 10 is set to 1.5, and the motor rotation speed V of the polygon mirror 140 is set to 1 / 1.5. rpm The laser was irradiated with a setting of 1 / 1.5 times. In addition, in order to maintain a constant distance between the focusing device 130 and the grain-oriented electrical steel sheet 10 in accordance with the change in the distance h, that is, to maintain a constant focusing shape, the position of the focusing device 130 was appropriately adjusted. When the magnetic properties were measured, the iron loss W 17 / 50 Although the magnetic flux density B8 increased slightly, the magnetic flux density B8 increased. Therefore, according to Example 2, it is possible to provide a material suitable for a transformer that places importance on the magnetic flux density B8.

[0056] [Example 3] In Example 3, as in the embodiment described above with reference to Fig. 10, two output devices 120 are installed facing each other on the upstream and downstream sides of the conveying direction L, and two laser beams 20 are moved by one polygon mirror 140. The conveying direction irradiation interval P L The laser beam 20 was irradiated between the linear heating regions formed by the output devices 120 by setting the distance G between the irradiation points of the laser beams 20 to 20 [mm] and 110 [mm]. The laser power P was 5000 [W], and the beam diameter D in the sheet width direction was C is doubled, and the power density I p The irradiation interval in the transport direction P L is 20 [mm] and the irradiation time T t = 40 [msec], the power density reduction is offset, and the input energy to the irradiation part is kept the same. P As a result of measuring the magnetic properties, the transport direction irradiation interval P L Since the other conditions were the same, the magnetic properties were also similar.

[0057] In the above-described embodiment, the laser processing apparatus 100 irradiates the surface of the workpiece 10 with the laser beam 20 using the polygon mirror 140, but the laser processing apparatus 100 according to the present disclosure is not necessarily limited to this, and may use a deflection device 150 such as another type of lens. As a modified example, there is a method in which a galvanometer mirror 151 is used for the deflection device 150 shown in FIG. 13. The laser processing apparatus 100 according to this modified example is composed of an output device 120, a focusing device 130, a deflection device 150 using the galvanometer mirror 151, and a synchronization device 160.

[0058] In the laser processing apparatus 100, the galvanometer mirror 151 is substantially parallel to the surface of the workpiece 10 and has a rotation axis RY perpendicular to the conveying direction L, and the laser processing apparatus 100 is provided with a mechanism for repeatedly rotating the galvanometer mirror 151 forward and backward around the rotation axis RY. Here, the galvanometer mirror 151 changes its reflection angle in accordance with the moving speed of the irradiation position, and when the galvanometer mirror 151 rotates forward, the reflected deflection direction of the laser light 20 coincides with the conveying direction L of the workpiece 10, and when the galvanometer mirror 151 rotates backward, the reflected deflection direction of the laser light 20 is opposite to the conveying direction L. The synchronization device 160 synchronizes the moving speed of the laser irradiation position on the workpiece 10 with the conveying speed V of the workpiece 10 when reflected by the forward rotating galvanometer mirror 151. L The rotation speed is adjusted to match the rotational speed of the workpiece 10, and the output device 120 generates a signal to control (ON / OFF) the output of the laser beam 20. As with the polygon mirror 140 described above, the galvanometer mirror 151 also decelerates from the start point of its forward rotation toward the center of its travel distance and then accelerates from the center toward the end point, and a signal is generated to stop the laser output during the deceleration period and during the period when the galvanometer mirror 151 is rotating in the reverse direction. By repeating these steps, the laser irradiation position is matched with the transport speed of the workpiece 10, and heated areas that approximately match the focused shape are formed at regular intervals in the transport direction.

[0059] Note that, as with the example of the laser processing apparatus 100 using the polygon mirror 140, deviations occur in the moving speed and conveying speed of the laser focusing position at the start point, center point, and end point, and in the change (deviation) in the focused light shape due to changes in the distance between the reflection point R of the galvanometer mirror 151 and the workpiece 10. However, these deviations can be adjusted to a range that does not affect the processing phenomenon by adjusting the arrangement of the galvanometer mirror 151 and the design of the focusing device 130. Also, a configuration using the fθ lens 133 shown in FIG. 7 may be used. Furthermore, the deflection device 150 is not limited to the above-described galvanometer mirror 151, and may include any type of deflection mirror that moves the irradiation position in the forward and reverse directions with respect to the conveyance direction L.

[0060] Figures 14 and 15 show another embodiment of the laser processing apparatus 100 using the deflection device 150 of Figure 13. The laser processing apparatus 100 according to this embodiment is composed of one output device 120, two sets of laser processing devices 1801, 1802 each consisting of a combination of deflection devices 1501, 1502 using galvanometer mirrors 1511, 1512 and focusing devices 1301, 1302, a laser beam guiding device 171 that guides laser light 20 to each of the laser processing devices 1801, 1802, an optical path switching device 170 that switches the laser output to each of the laser beam guiding devices 171, the two deflection devices 1501, 1502, the optical path switching device 170, and a synchronization device 160 that controls the operation of the output device 120. For example, in the laser processing apparatus 100, when the direction of reflection and deflection of the laser beam 20 by the galvanometer mirror 1511 of one laser processing device 1801 rotates forward and is the same as the conveying direction L of the workpiece 10, and when the moving speed of the laser focusing position is the same as the conveying speed of the workpiece 10, the laser beam 20 is guided to that laser processing device 180 by the optical path switching device 170. Meanwhile, the galvanometer mirror 1512 of the other laser processing device 1802 rotates in the reverse direction. At the timing when the rotation directions of the two devices switch, the optical path switching device 170 controls the laser beam 20 to be guided to the other device. That is, the laser beam 20 is guided to the laser processing device 1801 only while the galvanometer mirror 151 is rotating forward, and during that time the other galvanometer mirror 1512 rotates in the reverse direction. By alternately repeating this, the timing for stopping the laser output, which is required when there is only one laser processing device 180 as shown in FIG. 15, becomes unnecessary, thereby improving production efficiency.

[0061] 16, the optical path switching device 170 may be a rotary reflecting mirror 170 having slits 171 for transmitting the laser beam 20 provided at regular intervals on its circumference. The optical path is switched by the laser beam being reflected on the reflecting surface of the rotary reflecting mirror 170 and passing through the slits. That is, the synchronizer 160 synchronizes the timing of the laser output from the output device 120 with the reflection angle of the galvanometer mirror 151. The switching timing is controlled by the synchronizer 160 by controlling the rotation of the motor of the rotary reflecting mirror 170. Alternatively, any method capable of dividing the propagation direction of one laser beam 20 in time, such as switching the reflection direction of the laser beam 20, may be used.

[0062] FIG. 17 is a diagram showing a laser processing apparatus 100 using a reciprocating laser irradiation device 190. There is a method using the reciprocating laser irradiation device 190 shown in FIG. 17. The laser processing apparatus 100 according to this embodiment includes an output device 120, a reciprocating laser irradiation device 190, a synchronization device 160, and a drive mechanism 194. The reciprocating laser irradiation device 190 includes a focusing device 130 composed of lenses 191 and 192, and a reflecting mirror 193 as a deflection device 150. The drive mechanism 194 moves the reciprocating laser irradiation device 190 back and forth in the conveying direction L parallel to the surface of the workpiece 10 while keeping the relative positional relationship between the lenses 191 and 192 and the reflecting mirror 193 fixed. The reciprocating laser irradiation device 190 itself moves in the conveying direction L of the workpiece 10 at a conveying speed V L By moving at a speed V L It moves at the same speed Vc.

[0063] The synchronization device 160 is a device that synchronizes the driving of the reciprocating laser irradiation device 190 with the output and stop of the output device 120, and outputs laser light from the output device 120 when the reciprocating laser irradiation device 190 moves in the same direction and at the same speed as the conveyance direction L of the workpiece 10, and stops output from the output device 120 when the reflection mirror 193 serving as the deflection device 150 moves in the opposite direction to the conveyance direction L of the workpiece 10. By repeating these steps, the irradiation position is synchronized with the conveyance speed V of the grain-oriented electrical steel sheet 10.L , and heating regions that substantially match the focused shape are formed at regular intervals in the conveying direction L. The position and orientation of the reflecting mirror 193 are set so as to reflect the laser beam 20 focused by the lenses 191 and 192 serving as the focusing device 130 onto a predetermined irradiation position on the surface of the workpiece 10, as shown in FIG.

[0064] 18 and 19 show another embodiment of the apparatus using the reciprocating laser irradiation device 190 of Fig. 17. The laser processing apparatus 100 according to this embodiment is composed of one output device 120, two reciprocating laser irradiation devices 1901 and 1902, drive mechanisms 1941 and 1942, a laser beam guide device 171 that guides the laser beam 20 to each of the reciprocating laser irradiation devices 1901 and 1902, an optical path switching device 170 that switches the laser beam 20 to each of the laser beam guide devices 171, and a synchronization device 160 that controls the operation of the output device 120. The two reciprocating laser irradiation devices 1901 and 1902 operate differently from each other and move in the same direction as the conveying direction L at a conveying speed V L The same movement speed V cThe laser beam 20 from the output device 120 is guided by the optical path switching device 170 to one of the reciprocating laser irradiation devices 1901 moving in the same direction as the conveying direction L. Meanwhile, the other reciprocating laser irradiation device 1902 moves in the direction opposite to the conveying direction L without irradiating the workpiece 10 with the laser beam 20. At the timing when the moving directions of the two reciprocating laser irradiation devices 1901, 1902 are switched, the optical path switching device 170 controls the laser beam 20 to be guided to the other one. The moving directions and timing of the reciprocating laser irradiation devices 1901, 1902 are determined by controlling the driving mechanisms 1941, 1942 using a synchronization signal from the synchronizer 160. In other words, the laser beam 20 is guided to one of the reciprocating laser irradiation devices 1901, 1902 only when the laser beam 20 is moving in the same direction as the conveying direction L at the same speed. By repeating this alternately, it becomes unnecessary to set a timing for stopping the laser output from the output device 120, which is required when there is only one reciprocating laser irradiation device 190 as shown in Fig. 17, and it is possible to improve production efficiency. That is, the synchronizer 160 synchronizes the timing of the laser output from the output device 120 with the reciprocating movements of the reciprocating laser irradiation devices 1901 and 1902. Note that the deflection device 150 is not limited to the above-mentioned reflection mirror 193, and may include any type of mirror that moves reciprocally in the conveyance direction L to change the reflection direction.

[0065] In addition, in the present disclosure, the deflection device 150 may include multiple deflection devices 150 that form multiple laser beams 20 in the plate width direction C. When the major axis length of the linear focused shape is shorter than the width of the workpiece 10, for example, as shown in FIG. 20, multiple laser processing devices 100 already described may be arranged side by side in the width direction of the workpiece 10. In this case, multiple processing regions spaced apart from each other in the width direction of the workpiece 10 are formed. Note that the laser processing device 100 in FIG. 20 has polygon mirrors 1401 to 1404 as the deflection devices 150, but the present invention is not limited to this embodiment. The deflection device 150 included in the laser processing device 100 may be any of the deflection devices 150 already described.

[0066] 21 is a schematic diagram of another example of a laser processing apparatus 100 according to another embodiment of the present invention, and FIG. 22 is a schematic diagram of another example of a heating region according to another embodiment of the present invention. As shown in FIG. 22, the light-condensing shape formed by a single polygon mirror 140 may be a dot-array shape. Such a light-condensing shape can be achieved by adding, for example, a diffractive optical element 135 that utilizes the well-known diffraction phenomenon to one component of the light-condensing device 130, as shown in FIG.

[0067] Although the embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the specific embodiments described above, and various modifications and variations are possible within the scope of the gist of the present disclosure as set forth in the claims. For example, the workpiece 10 according to the present disclosure is not limited to a grain-oriented electrical steel sheet. Specifically, the workpiece 10 according to the present disclosure may be another type of electrical steel sheet, or any type of steel sheet other than an electrical steel sheet.

[0068] Furthermore, the thermal processing according to the present disclosure is not limited to forming grooves on the surface of the workpiece 10 described above. For example, the workpiece 10 may be a general steel plate, and the thermal processing according to the present disclosure may be used to facilitate identification of a position, area, etc. on the steel plate surface. As a specific example, the thermal processing according to the present disclosure may be used to facilitate visual recognition of defects detected on the steel plate surface. For example, when a defect is detected on the steel plate surface, a hole may be drilled at that position to facilitate identification of the location of the detected defect. In this way, when illumination light is irradiated onto the steel plate surface, the illumination light passes through the hole, making it possible to easily identify the location of the detected defect.

[0069] The disclosures of the specification, drawings and abstract contained in Japanese Patent Application No. 2024-017940, filed February 8, 2024, are incorporated herein by reference in their entirety. [Explanation of symbols]

[0070] 10 Grain-oriented electrical steel sheet 100 Laser processing equipment 110 Conveyor 120 Output Device 130 light collecting device 150 deflection device

Claims

1. A laser processing device that processes a surface of an object to be processed by irradiating it with laser light, an output device that outputs laser light; a focusing device that focuses the laser light into a predetermined focused shape; a deflection device that moves an irradiation position of the focused laser light on the surface of the object at the same moving speed as a conveying speed of the object conveyed in a first direction by a conveying device; and The focusing device forms the laser beam in a focused shape that is short in the first direction and long in a second direction perpendicular to the first direction.

2. The laser processing apparatus according to claim 1 , wherein the deflection device includes a plurality of deflection devices that form a plurality of the laser beams in the second direction.

3. 2. The laser processing device according to claim 1, wherein the deflection device includes a polygon mirror that rotates at a rotation speed corresponding to the movement speed of the irradiation position.

4. The laser processing apparatus according to claim 1 , wherein the deflection device includes a deflection mirror that moves the irradiation position in a forward direction and a reverse direction with respect to the first direction.

5. 5. The laser processing device according to claim 4, wherein the deflection device includes a galvanometer mirror that changes a reflection angle in response to a moving speed of the irradiation position.

6. 6. The laser processing device according to claim 5, further comprising a synchronization device that synchronizes the timing of the laser output from said output device with the reflection angle of said galvanometer mirror.

7. The laser processing apparatus according to claim 4 , wherein the deflection device includes a mirror that moves back and forth in the first direction to change the reflection direction.

8. 8. The laser processing device according to claim 7, further comprising a synchronization device that synchronizes the timing of laser output from said output device with the reciprocating movement of said mirror.

9. 9. The laser processing device according to claim 1, wherein the object is a grain-oriented electrical steel sheet.

10. 9. The laser processing device according to claim 1, wherein the deflection device has a function of adjusting an irradiation interval in the first direction.

11. A laser processing method for processing a surface of an object to be processed by irradiating the surface with laser light, comprising: a focusing step of focusing the laser light on the object being transported in a first direction at a predetermined transport speed; a moving step of moving an irradiation position of the focused laser light on the surface of the object to be processed at a moving speed that is the same as a conveying speed in the first direction; and The laser processing method, wherein the focusing step focuses the light into a focused shape that is short in the first direction and long in a second direction perpendicular to the first direction.

12. 12. The laser processing method according to claim 11, wherein the moving step moves the focused shape using a polygon mirror that rotates at a rotation speed corresponding to the moving speed of the irradiation position.

13. The laser processing method according to claim 11 , wherein the moving step moves the focused shape using a deflection mirror that moves the irradiation position in a forward direction and a reverse direction with respect to the first direction.

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