Steel plate processing device and steel plate processing method

Abstract

This steel plate processing device comprises one or more support rolls and a laser irradiation unit. The laser irradiation unit comprises a laser output part, a scanning optical part, a condensing optical part, a casing, and an angle adjustment part that changes an angle of the casing with respect to a steel plate. The angle adjustment part changes the angle of the casing in a plane formed by the normal direction of the steel plate and a scanning direction such that, when a surface of the steel plate is scanned with a laser beam, the laser beam condensed by the condensing optical part has the same distance between the condensing optical part and the surface of the steel plate over the entire length of an area of the surface of the steel plate to be scanned with the laser beam. The laser irradiation unit emits the laser beam with the angle of the casing having been changed by the angle adjustment part to form a groove portion or a distorted portion in the surface of the steel plate.

Description

[Technical Field]

[0001] The present invention relates to a steel plate processing device and a steel plate processing method. This application claims priority based on Japanese Patent Application No. 2022-049035, filed on March 24, 2022, the contents of which are incorporated herein by reference. [Background technology]

[0002] Electrical steel sheets are known to be used in transformer cores, contributing to the improvement of power loss. In the manufacturing process of such electrical steel sheets, a so-called magnetic domain control process is performed in which a steel sheet is scanned and irradiated with a focused laser beam in a direction substantially parallel to the sheet width direction while being fed at high speed, thereby forming linear distortions or grooves at regular intervals to reduce iron loss. It is known that magnetic domain control, which forms linear distortions or grooves, reduces the magnetic flux density when the steel sheet is magnetized, and the reduction in magnetic flux density is particularly significant when the linear grooves are formed in the same direction as the sheet width direction.

[0003] Furthermore, when magnetic domain-controlled electromagnetic steel sheets are used for wound cores, the steel sheets are bent in a later process, and if the linear grooves formed for magnetic domain control are aligned with the sheet width direction, stress concentration occurs in the grooves when the steel sheet is bent, which could result in the steel sheet breaking. Therefore, it is desirable to make the direction of the linear grooves not parallel to the sheet width direction; for example, Patent Document 1 discloses a technique in which the direction of the linear grooves is tilted by about 4° relative to the sheet width direction.

[0004] When a laser beam is irradiated onto a steel sheet, a portion of the laser beam irradiated onto the steel sheet is reflected and returned to the laser irradiation unit, which may damage components inside the device or the laser irradiation unit itself. The risk of a portion of the laser beam being reflected and returned to the laser irradiation unit may occur not only when a groove is formed in a steel sheet, but also when a distortion is formed.

[0005] According to the technology disclosed in Patent Document 1, a laser beam is irradiated onto the surface of a steel sheet that is conveyed while curving and contacting the surface of a support roll in an arc shape, at a position spaced apart from the reference point by an angle of 3° to 7° along the outer circumferential surface of the support roll, using a laser beam irradiation position that passes through the central axis of the support roll as a reference point. In this way, the steel sheet is inclined at the position where the laser beam is irradiated, and therefore, it is possible to prevent the laser beam from being specularly reflected from the steel sheet back to the irradiation device. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japan Special Publication No. 2019-512047 Summary of the Invention [Problem to be solved by the invention]

[0007] When the steel sheet is inclined in the sheet passing direction at the laser beam irradiation position and the linear groove direction is inclined by about 4° from the sheet width direction, the distance from the light source point of the scanned laser beam to the steel sheet differs at both ends in the scanning direction. This can cause the laser beam irradiated onto the steel sheet to be out of focus, making it difficult to form stable grooves or distortions. Therefore, in the technology disclosed in Patent Document 1, the support rolls are inclined so that the distance from the light source point of the laser beam to the steel sheet is the same at both ends in the scanning direction. However, inclining the support rolls not only makes it more likely that tension differences will occur at both ends of the steel sheet, causing meandering during sheet passing, but also causes tension changes in the sheet width direction, which can lead to the steel sheet breaking.

[0008] The present invention has been made to solve such problems, and has an object to provide a steel plate processing device and a steel plate processing method that can form uniform grooves or distortions by suppressing the defocusing of a laser beam irradiated onto a steel plate without tilting a support roll. [Means for solving the problem]

[0009] One aspect of the present invention is a steel plate processing device for forming grooves or distortions on the surface of a steel plate, the device comprising: one or more support rolls whose rotation axes are arranged parallel to the width direction of the steel plate and which rotate about the rotation axis to transport the steel plate supported on its outer surface in a transport direction perpendicular to the width direction; and a laser irradiation unit that irradiates a laser beam onto the surface of the steel plate located near or between the support rolls to form grooves or distortions on the surface of the steel plate. The laser irradiation unit comprises a laser output unit that outputs a laser beam to be irradiated onto the surface of the steel plate, a scanning optical unit that reflects the laser beam output from the laser output unit and varies the traveling direction of the laser beam, a focusing optical unit that collects the laser beam whose traveling direction has been varied by the scanning optical unit and irradiates the laser beam onto the surface of the steel plate so as to scan the surface of the steel plate in a scanning direction that intersects the width direction; a housing that houses the laser output unit, the scanning optical unit, and the focusing optical unit; and an angle adjustment unit that changes the angle of the housing with respect to the steel plate. The angle adjustment unit changes the angle of the housing in the plane formed by the normal direction of the steel plate and the scanning direction so that, when the surface of the steel plate is scanned with a laser beam, the laser beam focused by the focusing optical unit is focused on the surface of the steel plate over the entire length of the scanning line regardless of the optical path of the laser beam. In other words, the angle adjustment unit changes the angle of the housing in the plane formed by the normal direction of the steel plate and the scanning direction so that, when the surface of the steel plate is scanned with a laser beam, the distance from the focusing optical unit (light source point) to the steel plate surface is equal over the entire length of the scanning area of ​​the laser beam on the surface of the steel plate. Then, with the angle of the housing changed by the angle adjustment unit, the laser irradiation unit irradiates the laser beam to form grooves or distortions on the surface of the steel plate.

[0010] Another aspect of the present invention is a steel plate processing method for forming grooves or distortions on the surface of a steel plate, the method comprising: one or more support rolls whose rotation axes are arranged parallel to the width direction of the steel plate and which rotate about the rotation axis to transport the steel plate supported on its outer surface in a transport direction perpendicular to the width direction; and a laser irradiation unit that irradiates a laser beam onto the surface of the steel plate located near the support roll or between the plurality of support rolls to form grooves or distortions on the surface of the steel plate, the laser irradiation unit comprising a laser output unit that outputs a laser beam to be irradiated onto the surface of the steel plate; a scanning optical unit that reflects the laser beam output from the laser output unit and changes the traveling direction of the laser beam; a focusing optical unit that collects the laser beam whose traveling direction has been changed by the scanning optical unit and irradiates the laser beam onto the surface of the steel plate so as to scan the surface of the steel plate in a scanning direction that is a direction intersecting the width direction; a housing that stores the laser output unit, the scanning optical unit, and the focusing optical unit; and an angle adjustment unit that changes the angle of the housing with respect to the steel plate. This steel plate processing method includes an angle adjustment step in which the angle adjustment unit changes the angle of the housing in the plane formed by the normal direction of the steel plate and the scanning direction so that, when the surface of the steel plate is scanned with the laser beam, the laser beam focused by the focusing optical unit is focused on the surface of the steel plate regardless of the optical path of the laser beam, and a processing step in which the laser irradiation unit irradiates the laser beam with the angle of the housing changed by the angle adjustment unit to form grooves or distortions on the surface of the steel plate. That is, the other aspect is a steel plate processing method for forming grooves or distortions on the surface of a steel plate using a steel plate processing device. The steel plate processing device includes one or more support rolls whose rotation axes are arranged parallel to the width direction of the steel plate and which rotate about the rotation axes to transport the steel plate supported at its outer surface in a transport direction perpendicular to the width direction, and a laser irradiation unit that irradiates the surface of the steel plate located near the support rolls or between the plurality of support rolls with a laser beam from a focusing optical unit to form grooves or distortions on the surface of the steel plate. The steel plate processing method further includes an angle adjustment step of changing the angle of a housing of the laser irradiation unit in a plane defined by the normal direction of the steel plate and the scanning direction of the laser beam when scanning the surface of the steel plate with the laser beam so that the distance from the focusing optical unit (light source point) to the steel plate surface is equal over the entire length of the scanning area of ​​the laser beam on the surface of the steel plate, and a processing step of irradiating the steel plate with the laser beam from the focusing optical unit while the angle of the housing is changed to form grooves or distortions on the surface of the steel plate. [Effects of the Invention]

[0011] The steel plate processing apparatus of the above aspect of the present invention is provided with an angle adjustment unit that changes the angle of the housing of the laser irradiation unit with respect to the steel plate. The angle adjustment unit changes the angle of the housing in the plane formed by the normal direction of the steel plate and the scanning direction so that the laser beam is focused on the surface of the steel plate regardless of the optical path. That is, when scanning the surface of the steel plate with the laser beam, the angle adjustment unit changes the angle of the housing in the plane formed by the normal direction of the steel plate and the scanning direction so that the distance from the focusing optical unit to the surface of the steel plate is equal over the entire length of the scanning area of ​​the laser beam on the surface of the steel plate. As a result, the laser irradiation unit irradiates the laser beam with the housing angle changed by the angle adjustment unit, forming a groove or a distortion on the surface of the steel plate.

[0012] In this way, the angle of the housing relative to the steel sheet can be changed by the angle adjustment unit without tilting the support rolls, which suppresses meandering during sheet threading and reduces the risk of sheet breakage due to tension changes in the sheet width direction. Furthermore, by adjusting the angle of the housing relative to the steel sheet by the angle adjustment unit, the laser beam emitted from the laser irradiation unit attached to the housing is focused on the surface of the steel sheet regardless of the optical path. In other words, the distance from the focusing optical unit to the surface of the steel sheet is equal over the entire length of the laser beam scanning area. Therefore, it is possible to suppress defocusing of the laser beam over the entire width of the laser beam scanning, thereby forming uniform grooves or distortions. The same effect can also be obtained in the steel plate processing method according to the above aspect of the present invention. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing one embodiment of the present invention, and is a perspective view of a steel plate processing device for processing a steel plate. [Figure 2A] FIG. 2A is a configuration diagram of the laser irradiation unit of FIG. 1 in the YZ plane. [Figure 2B] FIG. 2B is a configuration diagram of the laser irradiation unit of FIG. 1 in the XZ plane. [Figure 3A] FIG. 3A is a configuration diagram of the laser irradiation unit as seen from the arrow A in FIG. [Figure 3B] FIG. 3B is a configuration diagram of the laser irradiation unit as seen from the arrow B in FIG. [Figure 4] FIG. 4 is a view of a laser irradiation unit configured to be movable in the laser irradiation direction, as viewed from the arrow A in FIG. [Figure 5] FIG. 5 is a view of another embodiment of a laser irradiation unit configured to be movable in the laser irradiation direction, as viewed from the arrow A in FIG. [Figure 6] FIG. 6 is a schematic diagram of a conventional steel plate processing device. [Figure 7]7A and 7B are diagrams illustrating the locations where the scanning area is set on the steel plate. Of these, (a) shows a flat location that is the target for setting the scanning area in this embodiment. Meanwhile, (b) and (c) show locations with uneven curved surfaces that are not the target for setting the scanning area. Furthermore, (d) shows point irradiation that is not the target for this embodiment. [Figure 8A] 8A is a schematic diagram of another conventional steel plate processing device, where (a) is a view seen from the direction along the axis of the support roll, and (b) is a view seen along the sheet threading direction. [Figure 8B] 8B is a schematic diagram of a steel plate processing device according to still another prior art, where (a) is a view seen from a direction along the axis of the support roll, and (b) is a view seen along the sheet threading direction. [Figure 9A] FIG. 9A is a view showing a case in which one end of a steel sheet is separated from the support roll and floats in another conventional technique, as viewed along the sheet passing direction. [Figure 9B] FIG. 9B is a diagram showing laser irradiation by the laser irradiation unit rotated by applying the steel plate processing device of this embodiment in the state shown in FIG. 9A, as viewed along the plate passing direction. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention and a modified example thereof will be described with reference to the drawings.

[0015] FIG. 1 is a perspective view showing a steel plate processing apparatus 100 of the present embodiment.

[0016] The steel plate processing device 100 includes a laser irradiation unit 1 and a support roll 2.

[0017] The support rolls 2 are arranged so that their rotation axes CL are parallel to the width direction of the steel sheet 3, and by rotating about the rotation axis CL, the steel sheet 3 supported at the upper part of its outer circumferential surface is passed through in a conveying direction perpendicular to the width direction. The steel sheet 3 is conveyed curved due to contact with part of the circumferential direction of the outer circumferential surface of the support rolls 2. The support roll 2 may be a single roll that supports the curved steel sheet 3, or may be composed of multiple support rolls 2 that apply tension to the steel sheet 3.

[0018] The laser irradiation unit 1 focuses a laser beam on the surface of the steel sheet 3 located near the support rolls 2, or on the surface of the steel sheet 3 between the support rolls 2 when the support rolls 2 are composed of multiple rolls, and irradiates the laser beam so as to linearly scan the surface of the steel sheet 3, thereby forming grooves or distorted portions on the surface of the steel sheet 3. Here, "arranging the rotation axes CL of the support rolls 2 so that they are parallel to the width direction of the steel sheet 3" can include not only a case where the rotation axes CL of the support rolls 2 and the width direction of the steel sheet 3 are completely aligned, but also a case where they are misaligned to an extent that allows the steel sheet 3 to be passed between the support rolls 2 in a stable manner.

[0019] 1 shows one laser irradiation unit 1, but when actually performing magnetic domain control on the steel sheet 3, a plurality of laser irradiation units 1 may be provided in the sheet width direction. With such a configuration, magnetic domain control can be performed on the entire region of the steel sheet 3 in the sheet width direction.

[0020] The following describes the details of the configuration of the laser irradiation unit 1. The laser irradiation unit 1 includes a laser output optical element 11 as a laser output section, a laser scanning optical element 12 as a scanning optical section, a laser focusing optical element 13 as a focusing optical section, a housing 14, an angle adjustment section 21, and a distance adjustment section 22. The laser output optical element 11, the laser scanning optical element 12, and the laser focusing optical element 13 (hereinafter collectively referred to as optical elements) are fixed, for example, to the bottom surface of the box-shaped housing 14 so that a relative positional relationship between them is maintained. Furthermore, the angle adjustment section 21 and the distance adjustment section 22 can use various known mechanical structures as long as they are structured to adjust the angle and distance of the housing 14, and in this drawing, they are simply illustrated as functional blocks for ease of explanation.

[0021] The housing 14 is provided with a laser transmission window 15, which is an opening through which the laser passes, and an inert gas supply port 16 and exhaust port 17. The angle adjustment unit 21 and the distance adjustment unit 22 are mechanisms that can adjust the angle of the housing 14 with respect to the steel plate 3 and the distance from the housing 14 to the steel plate 3, respectively. The angle adjustment operation (angle adjustment step) by the angle adjustment unit 21 will be described using Figures 3A and 3B, and the distance adjustment operation by the distance adjustment unit 22 will be described using Figures 4 and 5, which will be described later.

[0022] The laser output optical element 11 outputs a laser beam transmitted via a cable from a laser device (not shown) provided outside the laser irradiation unit 1. For example, the laser output optical element 11 includes a collimator that shapes the transmitted laser beam into a parallel beam having an elliptical or circular cross-sectional shape, and a mirror that reflects the beam shaped by the collimator in an appropriate direction.

[0023] The laser scanning optical element 12 reflects the laser beam output from the laser output optical element 11 and scans the laser beam by continuously changing the reflection angle. For example, the laser scanning optical element 12 may be a polygon mirror, which is a regular polygonal rotating mirror with multiple reflective flat mirrors around it, or a galvanometer mirror, which is a single flat mirror whose reflection direction is vibrated by a galvanometer motor.

[0024] The laser focusing optical element 13 focuses the scanning laser beam scanned by the laser scanning optical element 12 as, for example, a circular or elliptical micro-spot light at any one of positions arranged linearly on the surface of the steel sheet 3 in a direction intersecting the sheet width direction. For example, the laser focusing optical element 13 may be a linear parabolic mirror, an fθ lens, or a flat-field lens. Hereinafter, the laser beam focused by the laser focusing optical element 13 and irradiated onto the steel sheet 3 so as to scan will be referred to as the scanning laser beam. Furthermore, the region on the surface of the steel sheet 3 that is irradiated with the scanning laser beam will be referred to as the scanning region g.

[0025] The focal lengths of the collimators and focusing elements of the laser output optical element 11, the laser scanning optical element 12, and the laser focusing optical element 13, as well as the arrangement of each optical element, are determined so that the scanning laser beam forms a scanning area g of a desired focused shape on the steel sheet 3. The desired focused shape is a circular or elliptical micro-spot light shape, and is determined to be suitable for performing magnetic domain control in accordance with the characteristics of the electromagnetic steel sheet, in accordance with the scanning speed, laser power, etc. For example, when forming a groove approximately 20 μm deep, if the scanning speed is 20 m / s and the laser power is 1000 W, the diameter of the focused shape is approximately 50 μm. Note that this focused shape is merely an example and is not limited to this, and the focused shape may be other shapes than circular or elliptical.

[0026] The housing 14 is provided with a laser transmission window 15 through which the scanning laser beam output from the laser focusing optical element 13 can pass. For example, the laser transmission window 15 is a slit-shaped opening with the minimum size through which the scanning laser beam can pass. The housing 14 may also be referred to as a laser irradiation box or simply as a unit.

[0027] Furthermore, the housing 14 is provided with an inert gas supply port 16 and an exhaust port 17. The amount of inert gas supplied to the supply port 16 and the amount of inert gas exhausted from the exhaust port 17 are adjusted to keep the inside of the housing 14 filled with inert gas. The inert gas supplied to the inside of the housing 14 is exhausted not only from the exhaust port 17 but also from a laser transmission window 15 configured in a slit shape.

[0028] Here, when grooves and distortions are formed in the steel sheet 3 using a scanning laser beam, dust may be generated on the surface of the steel sheet 3. The dust is a component of the molten material of the electromagnetic steel sheet base material and the surface coating generated during the processing of the steel sheet 3, specifically, metal powders such as iron, silicon, and magnesium. Since it is difficult to completely collect this dust even with a dust collector, the dust spreads around the laser irradiation unit 1. If the generated dust adheres to the surface of an optical element, the adhered material absorbs the laser light, generating heat, which can cause optical distortion in the optical element, resulting in a deterioration of the light-gathering performance and a decrease in reflectance and transmittance. Furthermore, as the adhered material on the optical element oxidizes, the amount of laser light absorbed increases.

[0029] In this embodiment, the interior of the housing 14 is filled with an inert gas and maintained at a positive pressure relative to the ambient air pressure. The inert gas is a gas that does not contain oxygen and is resistant to oxidation or other chemical reactions, such as nitrogen or a rare gas such as argon or helium. By configuring the housing 14 in this manner, the housing 14 is filled with the inert gas and maintained at a positive pressure, preventing the inflow of oxygen-containing air and dust into the housing 14. This reduces the adhesion of foreign matter to the surfaces of the optical elements. Furthermore, even if foreign matter does adhere to the surfaces, it can be easily cleaned, thereby extending the life of the optical elements. A measuring device for monitoring the oxygen concentration and pressure may be installed inside the housing 14. In this case, the inflow of air from the outside may be monitored, and the amount of inert gas supplied from the supply port 16 may be increased upon detection of the inflow.

[0030] Furthermore, because the laser transmission window 15 through which the scanning laser beam is emitted is a slit-shaped opening, the inert gas inside the housing 14 is discharged through the laser transmission window 15. With this configuration, the inert gas flows out of the housing 14 from the laser transmission window 15, and this flow prevents dust and air from entering the housing 14 through the laser transmission window 15. The laser transmission window 15 may further be provided with a dust filter at its opening, which further prevents dust from entering the housing 14. Note that a measuring device for monitoring the oxygen concentration and pressure may be installed inside the housing 14. In this case, the inflow of air from outside may be monitored, and the amount of inert gas supplied from the supply port 16 may be increased when an inflow is detected.

[0031] In another embodiment, laser transmitting window 15 may be configured to block the flow of gas between the inside and outside of housing 14 via a window portion made of a material that is transmissive to the scanning laser beam, instead of a slit-shaped opening. The window portion of laser transmitting window 15 may be made of a material that is coated with an anti-reflective coating that suppresses reflection and absorption of the wavelength of the laser light.

[0032] In yet another embodiment, the supply port 16 and the exhaust port 17 do not have to be provided. When the laser transmission window 15 separates the inside and outside of the housing 14 and the supply port 16 and the exhaust port 17 are not provided, the housing 14 is sealed and filled with an inert gas. This makes it possible to prevent the inflow of oxygen-containing air and dust into the housing 14. Furthermore, since the area that is blocked from outside air and dust is limited to a relatively small area within the housing 14, blocking can be easily performed.

[0033] Furthermore, a measuring device for monitoring oxygen concentration and pressure may be attached to the housing 14 to detect an inflow of air from outside or a drop in the pressure of the inert gas. When an inflow of air or a drop in pressure is detected, the inert gas in the housing 14 may be replaced or refilled.

[0034] A gas injection nozzle may be provided near the laser transmission window 15 of the housing 14 to blow air or an inert gas onto the laser processing section to forcibly remove dust, in order to prevent dust flying up from the laser irradiation section from entering the laser transmission window 15. Also, a dust suction device may be provided near the processing section to forcibly collect dust.

[0035] The inventors conducted long-term tests to compare a structure in which the housing 14 is completely isolated from the outside air, with a case in which the interior is filled with air and a case in which the interior is filled with nitrogen to exclude oxygen and CO2. The results showed that when the interior was filled with air, clouding (clouding) occurred on the surfaces of the internal lenses and mirrors, resulting in a reduction of several percent in the transmittance and reflectance of the laser light. This clouding could not be completely removed even by cleaning with alcohol, and the optical components had to be replaced. On the other hand, when the housing was filled with nitrogen, slight clouding was observed on the surfaces of the lenses and mirrors, but this could be completely removed by cleaning, and there was no deterioration in the transmittance or reflectance.

[0036] Further detailed experimental evaluation revealed that keeping the oxygen concentration inside the box below 1% significantly reduced cloudiness, and that even slight cloudiness could be easily removed by cleaning. The cloudiness is thought to be caused by small amounts of dust remaining inside the box adhering to the mirror surface, and is formed by an oxidation reaction caused by the absorption of laser light. Therefore, in addition to sealing the box, filling the interior with an inert gas such as nitrogen or argon to keep the oxygen concentration below 1% is effective in maintaining the performance of optical components for the long term.

[0037] The following describes the positional relationships of the optical elements within the housing 14. In the following description, the positional relationships will be explained using the X, Y, and Z axes and the S-axis shown in FIG. 1. The X-axis indicates a direction parallel to the rotation axis CL of the cylindrical support roll 2, the Z-axis indicates the vertical direction, and the Y-axis indicates the direction in which the steel sheet 3 passes. The vertical Z-axis indicates the normal direction to the passing surface of the steel sheet 3. The passing surface of the steel sheet 3 refers to the surface of the steel sheet 3 at the apex of the steel sheet 3 supported by the support rolls 2, or the surface of the portion of the passing steel sheet 3 that is not tilted by the support rolls 2. Therefore, the normal direction to the passing surface of the steel sheet 3 corresponds to the vertical direction. The S-axis indicates the scanning direction of the scanning laser beam. The laser irradiation unit 1 has an angle adjustment function that allows the housing 14 to be rotated. Details of the rotation will be explained using FIGS. 3A and 3B, which are views from A and B in FIG. 1.

[0038] 2A is a diagram showing the YZ plane as viewed from the X-axis direction in FIG. 1. As shown in FIG. 2A, in the cross-sectional direction of the support roll 2, the steel sheet 3 contacts along an arc centered at the upper vertex in the Z-axis direction. The contact portion between the support roll 2 and the steel sheet 3 is arc-shaped in the YZ plane and extends in the direction of the rotation axis CL (X-axis). Of this contact portion, the contact portion on the upstream side in the sheet passing direction (negative side of the Y-axis) is referred to as P. The scanning laser beam output from the laser irradiation unit 1 indicated by the arrow is irradiated at a position spaced apart from this contact portion P upstream in the sheet passing direction (negative side of the Y-axis).

[0039] In this way, by irradiating the scanning laser beam at a position spaced upstream of the contact part P in the sheet passing direction, the surface of the steel sheet 3 does not face the incident direction of the scanning laser beam. As a result, the reflected light from the steel sheet 3 does not head directly toward the laser irradiation unit 1, preventing damage to the laser irradiation unit 1. Furthermore, because the irradiation point of the scanning laser beam is close to the contact part P, there is little vibration of the steel sheet 3 at the irradiation point of the scanning laser beam, and it is possible to suppress defocusing due to vibration.

[0040] 2B is a diagram showing the XZ plane as viewed from the Y-axis direction in FIG. 1. As shown in FIG. 2B, the S-axis, which is the scanning direction of the scanning laser beam, is inclined with respect to the X-axis, which is the width direction of the steel sheet 3. Therefore, in the scanning area g of the scanning laser beam on the steel sheet 3, the distances L1 and L2 from both ends in the scanning direction to the irradiation source of the scanning laser beam are not equal to each other, and a difference occurs. If the distance from the irradiation source of the scanning laser beam to the steel sheet 3 changes along the scanning direction in this way, defocusing may occur, and stable grooves or thermal distortion may not be formed across the entire width of the scanning area g.

[0041] Therefore, the laser irradiation unit 1 is provided with an angle adjustment unit 21 that adjusts the rotation angle by rotating the housing 14. The angle adjustment unit 21 according to this embodiment adjusts the angle of two types of rotation, for example, as shown in FIGS. 3A and 3B. By rotating within the ZS plane shown in FIG. 3A, the distance between the laser irradiation unit 1 and the steel plate 3 can be adjusted so that the focal position of the irradiated scanning laser beam coincides with the surface of the steel plate 3. By rotating within the XY plane shown in FIG. 3B, the S axis, which is the scanning direction of the scanning laser beam, can be tilted with respect to the X axis, which is the width direction of the steel plate 3.

[0042] 3A is a view seen from direction A in FIG. 1 (a direction perpendicular to the X axis from which the side of the laser irradiation unit 1 can be observed), and is an explanatory diagram of rotation within the ZS plane. FIG. 3B is a view seen from direction B in FIG. 1 (a direction perpendicular to the X axis from which the top surface of the laser irradiation unit 1 can be observed), and is an explanatory diagram of rotation within the XY plane. As shown in these figures, the housing 14 is configured to be rotatable independently within both the SZ plane and the XY plane.

[0043] Specifically, as shown in FIG. 3A , the rotation of the housing 14 within the ZS plane is performed so that the center of the scanning area g, where the scanning laser beam is focused, is the rotation center. That is, in the angle adjustment step, the entire laser irradiation unit 1 is rotated by rotating the housing 14 around an axis that passes through the center of the scanning area g of the scanning laser beam and is perpendicular to the ZS plane. By such rotation, even if the steel sheet 3 is inclined in the sheet passing direction at the irradiation position of the scanning laser beam and the scanning direction of the scanning laser beam is inclined from the sheet width direction, the scanning laser beam can be focused on the surface of the steel sheet 3 regardless of the optical path in the processing step following the angle adjustment step. Here, since the rotation center of the housing 14 is set at the center point between one end and the other end of the scanning area g, the rotation of the housing 14 according to the set scanning area g can be controlled more easily and accurately than when the rotation center is set at a position shifted from the center point toward the one end or the other end.

[0044] A specific example of the configuration of angle adjustment unit 21 that achieves angle adjustment by such rotation is as follows: The angle adjustment unit 21 may be configured with a pair of fulcrums that face each other via the center point of the scanning area g in an axial direction (the direction toward the front and rear of the paper) that passes through the center point of the scanning area g and is perpendicular to the ZS plane, a fixing plate that fixes the bottom surface of the laser irradiation unit 1 and extends in this axial direction, and arms that connect the pair of fulcrums to both ends of the fixing plate in this axial direction. The angle adjustment unit 21 is not limited to this configuration and may have any configuration as long as it can rotate the housing 14 around an axis that passes through the center point of the scanning area g and is perpendicular to the ZS plane.

[0045] As shown in Figure 2B, the scanning direction (S-axis) of the scanning laser beam is inclined with respect to the sheet width direction (X-axis), which causes a difference between the distances L1 and L2 from the irradiation source of the scanning laser beam to both ends of the scanning area g on the steel sheet 3. If the distance from the irradiation source to the steel sheet 3 changes in the scanning direction, a focus error occurs, which may result in failure to form the intended grooves or thermal distortions across the entire width of the scanning area g in the scanning direction. Therefore, by using a rotation mechanism with the angle adjustment unit 21 to tilt the housing 14 integrally in the ZS plane, the focal position can be aligned with the surface of the steel sheet 3 across the entire width of the scanning area g in the scanning direction so that L1 and L2 are equal and the difference between them is eliminated.

[0046] Furthermore, as shown in FIG. 3B, the housing 14 is configured to be rotatable within the XY plane. When rotating within the XY plane, the center of the scanning area g serves as the center of rotation. That is, the housing 14 has a function of rotating the entire laser irradiation unit 1 around an axis that passes through the center of the scanning area g of the scanning laser beam and is perpendicular to the XY plane. By such rotation, the scanning direction of the scanning laser beam can be tilted with respect to the width direction of the steel sheet 3.

[0047] By rotating the laser irradiation unit 1 in the XY plane in this way, the irradiation scanning direction (S-axis) of the scanning laser beam is adjusted to a desired angle with respect to the sheet width direction (X-axis). Here, the desired angle is, in magnetic domain control for groove formation, preferably 4° or more and 10° or less so as to reduce deterioration of the magnetic flux density of the electromagnetic steel sheet, increase the iron loss improvement effect, and prevent breakage during bending when used in an iron core; in magnetic domain control for thermal distortion, preferably greater than 0° and 10° or less so as to increase the iron loss improvement effect.

[0048] As a method for controlling angle adjustment unit 21 to optimally set the rotation (tilt) angle of housing 14, for example, laser range finders may be installed at both ends of the scanning line to measure the distance between L1 and L2, and the rotation (tilt) of housing 14 may be adjusted so that the lengths of L1 and L2 become the same value. Alternatively, the emission intensity of generated dust particles and molten droplets (spatter) of the base material in the part of steel plate 3 irradiated with the scanning laser beam may be observed with a camera, and angle adjustment unit 21 may be controlled to adjust the rotation (tilt) of housing 14 so that the emission intensity becomes uniform.

[0049] As described above, in the laser irradiation unit 1 of this embodiment, the laser output optical element 11, the laser scanning optical element 12, and the laser focusing optical element 13, which determine the focused shape and scanning width of the laser beam, are fixed in position within the housing 14. Therefore, the focused shape and scanning width are not affected even if the housing 14 is rotated or tilted as a whole. Furthermore, the housing 14 has a function of rotating the entire laser irradiation unit 1 about an axis that passes through the center of the scanning region g and is perpendicular to the ZS plane. This eliminates the need to tilt the support roll 2 and eliminates the difference between the distances L1 and L2 from the irradiation source of the scanning laser beam to both ends of the scanning region g of the steel sheet 3. As a result, the focal position coincides with the surface of the steel sheet 3 over the entire width of the scanning region g while suppressing the occurrence of meandering during sheet threading, thereby enabling the formation of uniform grooves or distortions.

[0050] Furthermore, in the past, when a problem arose with the focusing shape, scanning width, etc., adjusting one of the optical elements, namely the laser output optical element 11, the laser scanning optical element 12, and the laser focusing optical element 13, would affect the remaining two, making the adjustment difficult. However, by integrating these optical elements into the laser irradiation unit 1, adjustments can be made easily.

[0051] Furthermore, since the housing 14 rotates so that the center of the scanning area g is the center of rotation, it is possible to correct defocusing over the entire width of the scanning area g in the scanning direction simply by adjusting the rotation.

[0052] Furthermore, the laser irradiation unit 1 of this embodiment includes a distance adjustment unit 22 in addition to the angle adjustment unit 21. Adjustment by the distance adjustment unit 22 allows the rotation center of the housing 14 to be aligned with the scanning area g with higher accuracy, thereby correcting any slight defocus. As shown in FIG. 4 or 5 , the distance adjustment unit 22 adjusts the position of the housing 14 or the laser focusing optical element 13 so that the light source point of the scanning laser beam moves relative to the steel plate 3 along the laser irradiation direction L. Note that, when the laser focusing optical element 13 is a focusing reflecting mirror such as a parabolic mirror, the laser irradiation direction L is an axis passing through the center of the scanning line of the laser beam on the mirror surface and the center of the scanning line on the steel plate. When the laser focusing optical element 13 is a lens such as an fθ lens, the laser irradiation direction L is an axis passing through the center of the scanning line of the laser beam on the lens surface and the center of the scanning line on the steel plate.

[0053] 4 is a view seen from the direction A in FIG. 1 and is an explanatory diagram of movement within the SZ plane. As shown in this figure, the entire housing 14 is configured to be movable along the L axis, which is the irradiation direction of the scanning laser beam. With this configuration, the focal position of the scanning laser beam can be further adjusted along the L axis, so that the center of rotation of the housing 14 can be aligned with the center of the scanning area g. In other words, the focal point of the scanning laser beam can be aligned with the surface of the steel sheet 3.

[0054] A specific example of the configuration of distance adjustment unit 22 that achieves such distance adjustment is as follows: Distance adjustment unit 22 may be configured with a guide along the L axis, which is the irradiation direction of the scanning laser beam, and a fixing base that is configured to be movable along this guide and to fix housing 14 or laser focusing optical element 13. Distance adjustment unit 22 is not limited to this configuration, and may have any configuration as long as it is possible to move housing 14 or laser focusing optical element 13 along the L axis, which is the irradiation direction of the scanning laser beam.

[0055] In order to make the light source point of the scanning laser beam movable relative to the steel plate 3, the laser irradiation unit 1 may be configured as shown in FIG. 5. Like FIG. 4, FIG. 5 is a view seen from direction A in FIG. 1 and is an explanatory diagram of movement within the SZ plane. As shown in this figure, the laser focusing optical element 13 inside the housing 14 is configured to be movable along the L axis. Even with this configuration, the focal position of the scanning laser beam can be adjusted along the L axis, making it easier to align the focal point with the surface of the steel plate 3.

[0056] Furthermore, when focusing the focusing optical element 13 on the steel plate surface over the entire length of the scanning area g, the laser output optical element 11 and the laser scanning optical element 12 are fixed to the housing 14, so there is no need to adjust the angle or position, and the laser focusing optical element 13 only needs to be moved in the L direction for adjustment. Therefore, focus adjustment is easy, and there is no fluctuation in the position or angle of the optical element due to ambient vibrations or heat, etc., allowing for stable processing. Alternatively, as another configuration, a configuration having both the adjustment function of FIG. 4 and the adjustment function of FIG. 5 may be adopted.

[0057] FIG. 6 illustrates a conventional technique different from this embodiment, which shows a method for matching the distances L1 and L2 from the light source point of the scanning laser beam to both ends of the scanning area g on the steel sheet 3. As shown in this figure, the support rolls 2 are tilted to match L1 and L2. However, tilting the support rolls 2 could destabilize the sheet threading, which could lead to meandering or breakage of the steel sheet 3. In contrast, according to this embodiment, the entire laser irradiation unit 1, rather than the steel sheet 3, is rotated by the angle adjustment unit 21. This does not change the positional relationship between the support rolls 2 and the steel sheet 3, reducing the risk of meandering or breakage of the steel sheet 3.

[0058] As described above, according to this embodiment, an angle adjustment unit 21 is provided that changes the angle of the housing 14 of the laser irradiation unit 1 relative to the steel plate 3, and this angle adjustment unit 21 changes the angle of the housing 14 so that the laser beam is focused on the surface of the steel plate 3 regardless of the optical path. That is, when the surface of the steel plate 3 is scanned with a laser beam, the angle adjustment unit 21 changes the angle of the housing 14 in the ZS plane formed by the normal direction (Z-axis direction) of the steel plate 3 and the scanning direction (S-axis direction) so that the distance from the focusing optical element 13 (light source point) to the surface of the steel plate 3 is equal over the entire length of the scanning area g of the scanning laser beam on the surface of the steel plate 3. At this time, for example, when one end and the other end of the scanning area g are viewed, the distances L1 and L2 become equal to each other. As explained above, the distance from the focusing optical element 13 (light source point) to the surface of the steel plate 3 is made equal at each position over the entire length of the scanning area g of the scanning laser beam, and as a result, defocusing of the scanning laser beam is suppressed over the entire scanning width on the surface of the steel plate 3, making it possible to form uniform grooves or distorted portions.

[0059] As a supplementary note, in this embodiment, a scanning area g is set by selecting a location on the steel sheet 3 during passing where a flat surface can be obtained, as shown in Fig. 7(a). Then, the laser irradiation unit 1 is fixed in a fixed position without moving relative to the set scanning area g, and a laser beam is scanned to form a uniform groove or distorted portion in the scanning area g. On the other hand, in the case of a portion of the steel plate 3 that is a concavely curved surface or a convexly curved surface, as shown in Figure 7(b) or Figure 7(c), the portion includes a defocused portion within the scanning area g, and therefore is not included in the setting of the scanning area g. In addition, in FIG. 7(d), the laser irradiation unit itself moves to move the point-like irradiation position, and laser beam scanning is not performed, so this is outside the scope of this embodiment.

[0060] (Variation) 8A and 8B show a method of threading a steel sheet 3 in another conventional technique different from this embodiment. In the example shown in Fig. 8A, the steel sheet 3 is transported flat on the support rolls 2 without being curved due to contact with a part of the circumferential direction of the outer circumferential surface of the support rolls 2. However, there are cases where the steel sheet 3 is transported in a state where it is separated from the support rolls 2 at one end in the X-axis direction and floats due to a defective shape of the steel sheet 3 or an uneven balance of tension applied to the steel sheet 3 (i.e., the steel sheet 3 is transported tilted in the X direction).

[0061] In addition, the example shown in Figure 8B is a case where the laser irradiation unit 1 is provided between multiple support rolls 2, and for the same reason as in the case of Figure 8A, the steel sheet 3 is transported in a state where it is separated from the support roll 2 and floats at one end of the support roll 2 in the X-axis direction.

[0062] In these cases, the steel plate 3 is transported while tilted toward the plate width direction. Therefore, even if the scanning direction (S-axis) of the scanning laser beam is set to be parallel to the plate width direction (X-axis), a difference occurs in the distances L1 and L2 from the light source point of the scanning laser beam to both ends of the scanning area g on the steel plate 3, as shown in Figure 9A, and the formation of grooves and thermal distortion on the scanning line becomes unstable.

[0063] 9A, when the steel plate processing apparatus of this embodiment is applied in a state in which grooves and thermal distortion formation on the scanning line are unstable, as shown in Fig. 9B, by rotating the laser irradiation unit 1 using the angle adjustment part 21, even if the steel plate 3 is tilted in the plate width direction, the focal position of the scanning laser beam can be stably matched on the surface of the steel plate 3 by rotating the laser irradiation unit 1, and as a result, the laser beam can be focused on the surface of the steel plate 3 regardless of the optical path of the laser beam. In other words, the distance from the focusing optical element 13 to the surface of the steel plate 3 becomes equal over the entire length of the scanning area g of the scanning laser beam on the surface of the steel plate 3. In this way, the steel plate processing apparatus and steel plate processing method of this embodiment can be applied to processing the steel plate 3 on the inclined surface near the support roll 2 as described in Figure 2A etc., as well as processing the steel plate 3 at a position between a pair of support rolls 2 as described in Figure 8B.

[0064] The present invention is not limited to the configurations and processes of the above-described embodiments and various modifications, and may be modified as necessary. Furthermore, the above-described embodiments and various modifications are intended to explain the present invention and do not limit the scope of the present invention. That is, the scope of the present invention is defined by the claims, not the embodiments. Various modifications made within the scope of the claims and within the meaning of the invention equivalent thereto are considered to be within the scope of the present invention. [Industrial Applicability]

[0065] According to the above-described embodiment and various modified examples of the present invention, it is possible to provide a steel plate processing apparatus and a steel plate processing method that can form uniform grooves or distortions by suppressing the defocusing of a laser beam irradiated onto a steel plate, and thus has great industrial applicability. [Explanation of symbols]

[0066] 1 Laser irradiation unit 2 Support Rolls 3 steel plate 11 Laser output optical element (laser output section) 12 Laser scanning optical element (scanning optical section) 13 Laser focusing optical element (focusing optical section) 14. Case 15 Laser transmission window 16 Supply port 17 Outlet 21 Angle adjustment section 22 Distance adjustment section 100 Steel plate processing equipment CL Rotational Axis g Scanning area L1,L2 distance

Claims

1. A steel plate processing device that forms a groove or a distortion on the surface of a steel plate, a laser irradiation unit that irradiates a laser beam onto a surface of the steel plate located near one or more support rolls or between a plurality of support rolls that rotate around the rotation axis and transport the steel plate supported on its outer surface in a transport direction perpendicular to the plate width direction, thereby forming grooves or distorted portions on the surface of the steel plate; The laser irradiation unit includes: a laser output unit that outputs a laser beam to be irradiated onto the surface of the steel plate; a scanning optical unit that reflects the laser beam output from the laser output unit and changes the traveling direction of the laser beam; a focusing optical unit that focuses the laser beam whose traveling direction has been changed by the scanning optical unit, and irradiates the surface of the steel sheet with the laser beam so as to scan the surface of the steel sheet in a scanning direction that is a direction intersecting the sheet width direction; a housing that houses the laser output unit, the scanning optical unit, and the focusing optical unit; an angle adjustment unit that changes the angle of the housing with respect to the steel plate; and the angle adjustment unit changes the angle of the housing in a plane formed by a normal direction of the steel plate and the scanning direction so that, when the surface of the steel plate is scanned with the laser beam, the laser beam focused by the focusing optical unit is equal in distance from the focusing optical unit to the surface of the steel plate over the entire length of a scanning area of ​​the laser beam on the surface of the steel plate, and the laser irradiation unit irradiates the laser beam while the angle of the housing is changed by the angle adjustment unit, thereby forming a groove or a distortion portion on the surface of the steel plate. Steel plate processing equipment.

2. a distance adjustment unit that moves the housing or the focusing optical unit in the irradiation direction of the laser beam to the steel plate to change the distance of the focusing optical unit to the steel plate, 2. The steel plate processing device according to claim 1, wherein the distance adjustment unit changes the distance of the focusing optical unit relative to the steel plate in the irradiation direction of the laser beam so that, when the surface of the steel plate is scanned with the laser beam, the distance from the focusing optical unit to the surface of the steel plate is equal over the entire length of the scanning area of ​​the laser beam focused by the focusing optical unit.

3. the housing has a laser transmission window that transmits the laser beam; The focusing optical unit focuses and irradiates the laser beam onto the surface of the steel plate through the laser transmission window, The steel plate processing device according to claim 1 or 2, wherein the housing is filled with an inert gas.

4. The housing includes: a laser transmission window that transmits the laser beam; The focusing optical unit focuses and irradiates the laser beam onto the surface of the steel plate through the laser transmission window, 3. The steel plate processing device according to claim 1, wherein the inside of said housing is isolated from the atmosphere outside said housing and is filled with an inert gas.

5. A steel plate processing method for forming a groove portion or a distortion portion on a surface of a steel plate using a steel plate processing device, The steel plate processing device a laser irradiation unit that irradiates a laser beam from a focusing optical unit onto a surface of the steel plate located in the vicinity of one or more support rolls or between a plurality of support rolls, the support rolls rotating about the rotation axis and transporting the steel plate supported on its outer surface in a transport direction perpendicular to the plate width direction, thereby forming grooves or distorted portions on the surface of the steel plate; an angle adjustment step of changing an angle of a housing of the laser irradiation unit in a plane formed by a normal direction of the steel plate and a scanning direction of the laser beam so that, when scanning the surface of the steel plate with the laser beam, a distance from the focusing optical unit to the surface of the steel plate is equal over the entire length of a scanning area of ​​the laser beam on the surface of the steel plate; a processing step of irradiating the laser beam from the focusing optical unit with the housing at a changed angle to form a groove or a distortion on the surface of the steel plate; A steel plate processing method comprising the steps of:

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