Steel sheet processing apparatus and control method for steel sheet processing apparatus

Abstract

This steel plate processing device comprises: a laser emission unit that forms a groove in the surface of a steel plate; an illumination unit that emits a pulsed beam onto the groove; an image capture unit that generates a captured image by capturing the groove illuminated by the pulsed beam at an exposure time longer than the emission time of the pulsed beam; a determination unit that performs determination based on the captured image; and a processing control unit that controls the operation of the laser emission unit. The determination unit determines whether the groove satisfies a first standard on the basis of the captured image. If the determination unit determines that the groove does not satisfy the first standard, the processing control unit controls the laser emission unit such that the groove formed by the laser emission unit satisfies the first standard.

Description

[Technical Field]

[0001] The present invention relates to a steel sheet processing apparatus and a control method for a steel sheet processing apparatus. This application claims priority based on Japanese Patent Application No. 2022-068829, filed in Japan on April 19, 2022, and the contents of that application are incorporated herein by reference. [Background technology]

[0002] Various processing techniques are applied to steel sheets. For example, there are various technologies that improve the performance of steel sheets, such as surface friction characteristics and adhesion, by applying laser processing to the surface of the steel sheet. A more specific example is the laser magnetic domain control process, which improves iron loss by forming grooves with a depth of several tens of micrometers on the surface of electrical steel sheets. In the laser magnetic domain control process for electrical steel sheets, a focused laser beam is irradiated onto the surface of the steel sheet being passed through, and is repeatedly scanned along a direction approximately parallel to the width direction of the steel sheet. This forms linear grooves on the surface of the steel sheet at regular intervals along the direction in which the steel sheet is passed through. By forming these grooves, the magnetic domains of the electrical steel sheet are subdivided, and iron loss can be reduced.

[0003] In detail, when forming grooves in the laser magnetic domain control process, a strip of electrical steel sheet is continuously passed (conveyed) in the longitudinal direction while a laser beam is irradiated onto the surface of the steel sheet. By scanning the laser beam in a direction approximately parallel to the width direction of the steel sheet, grooves with a depth of 20-30 [μm] are formed in the steel sheet. The cross-sectional shape of the grooves formed in this case greatly affects iron loss and magnetic flux density.

[0004] Generally, the processing quality of steel plates using a laser beam depends not only on the laser power but also on processing conditions such as the laser beam diameter and scanning speed. Therefore, changes in the power of the laser irradiation device, changes in the beam diameter due to focus fluctuations of the laser focusing element, and changes in the laser scanning speed may cause the shape of the formed grooves to fail to meet the predetermined standards such as depth and width required in the magnetic domain control process.

[0005] Patent Document 1 discloses a technique in which a leakage magnetic flux sensor is installed downstream in the sheet passing direction of a laser grooving section to detect the magnetic flux leaking from the surface of a steel sheet on which a groove is formed, and to determine the quality of the groove. According to this technique, a leakage magnetic flux signal generated when a groove of a desired shape is formed is acquired in advance as a reference, and by comparing this reference signal with the leakage magnetic flux signals continuously obtained on the production line, the quality of the groove can be determined.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, when measuring the leakage magnetic flux using the technique disclosed in Patent Document 1, if the groove is as shallow as about 30 [μm], the leakage magnetic flux generated from the groove occurs only in the extremely near vicinity of the steel sheet surface. Therefore, there is a problem that a leakage magnetic flux sensor with high measurement accuracy needs to be arranged extremely close to the steel sheet surface.

[0008] Also, the leakage magnetic flux signal used in the technique disclosed in Patent Document 1 is affected by the surface unevenness of the steel sheet, the cross-sectional shape of the groove, surface states such as cracks and scratches in the base material, and inclusions. Therefore, by providing the leakage magnetic flux sensor on the opposite side of the groove formation surface, the influence of the leakage magnetic flux due to the molten protrusions and scratches generated on the surface of the steel sheet is reduced. However, since the detected leakage magnetic flux signal becomes even smaller, for example, when the steel sheet is being conveyed at a predetermined sheet passing speed, measurement errors are likely to occur, and even if an attempt is made to process a groove based on the detected leakage magnetic flux signal, there is a risk that a steel sheet with a well-processed groove cannot be stably obtained.

[0009] The present invention was made to solve these problems, and aims to provide a steel sheet processing apparatus and a control method for the steel sheet processing apparatus that can stably produce steel sheets with well-processed grooves while conveying the steel sheets. [Means for solving the problem]

[0010] In order to solve the above problems and achieve the aforementioned objectives, the present invention employs the following embodiments. (1) One aspect of the present invention is: A steel sheet processing apparatus for processing grooves on the surface of a steel sheet that is passed through in the direction of sheet passage, A laser irradiation unit that irradiates the surface with a laser beam to form grooves parallel or substantially parallel to the width direction of the steel plate, An illumination unit that irradiates pulsed light into the groove formed by the laser irradiation unit, An imaging unit generates an image by imaging the groove irradiated with the pulsed light for an exposure time longer than the irradiation time of the pulsed light, A determination unit that performs a determination based on the captured image, A processing control unit that controls the operation of the laser irradiation unit, It has, The determination unit determines, based on the captured image, whether the groove satisfies a first criterion relating to at least one of the depth and width of the groove. If the determination unit determines that the groove does not meet the first criterion, the processing control unit controls the laser irradiation unit so that the groove formed by the laser irradiation unit meets the first criterion.

[0011] (2) The above (1) may be configured as follows: When viewed in cross-section along the thickness direction of the steel plate, The illumination unit has an illumination optical axis that is on one side with respect to the normal of the surface, The imaging unit includes a first camera having a first incident optical axis that is in a specular reflection position with respect to the illumination optical axis on the other side of the normal, and a second camera having a second incident optical axis that is different from the specular reflection position.

[0012] (3) The above (2) may be configured as follows: In the aforementioned cross-section, the angle between the normal and the illumination light axis is θ. L (°), the angle between the normal and the first incident optical axis is θ. C1 (°), the angle between the normal and the second incident optical axis is θ. C2 When (°) is used, the following equations 1 to 3 are satisfied. θ C1 = -θ L ...(Formula 1) θ C2 =A-θ L ...(Formula 2) 60°≦A≦120° (Formula 3)

[0013] (4) The above (3) may be configured as follows: Based on the image captured by the first camera and the image captured by the second camera, the determination unit further determines whether the inclination angle of the side wall of the groove in the cross-section satisfies a second criterion. If the determination unit determines that the second criterion is not met, the processing control unit controls the laser irradiation unit so that both the first and second criterions are met.

[0014] (5) Any one of the above items (1) to (4) may be constructed as follows: The system further includes a removal unit for removing protrusions formed in the groove, The processing control unit controls the removal unit in addition to controlling the laser irradiation unit. The illumination unit and the imaging unit are positioned downstream in the direction of the plate passage from the position of the removal unit. The determination unit, based on the captured image, A first determination unit that determines whether the groove satisfies the first criterion, The system includes a second determination unit that determines whether the projection formed in the groove satisfies a third criterion relating to at least one of the height and width of the projection, If the second determination unit determines that the protrusion does not meet the third criterion, the processing control unit controls the removal unit to remove the protrusion.

[0015] (6) The above (5) may be configured as follows: The system further comprises another illumination unit and an imaging unit positioned between the laser irradiation unit and the removal unit in the direction of plate passage.

[0016] (7) Any one of the above items (1) to (5) may be constructed as follows: A tracking unit that acquires the position of the groove and the position of the protrusion on the surface of the steel plate, A mapping unit creates a map that includes groove information linking the position of the groove and the shape of the groove, and protrusion information linking the position of the protrusion and the shape of the protrusion. To further prepare.

[0017] (8) Other aspects of the present invention are: A steel sheet processing apparatus for processing grooves on the surface of a steel sheet that is passed through in the direction of sheet passage, A laser irradiation unit that irradiates the surface with a laser beam to form grooves parallel or substantially parallel to the width direction of the steel plate, An illumination unit that irradiates pulsed light into the groove formed by the laser irradiation unit, An imaging unit generates an image by imaging the groove irradiated with the pulsed light for an exposure time longer than the irradiation time of the pulsed light, A determination unit that performs a determination based on the captured image, A removal unit for removing protrusions formed in the groove, A processing control unit that controls the operation of the removal unit, It has, The determination unit determines, based on the captured image, whether the protrusion formed in the groove satisfies a third criterion relating to at least one of the height and width of the protrusion. If the determination unit determines, based on the captured image, that the protrusion does not meet the third criterion, the processing control unit controls the removal unit to remove the protrusion.

[0018] (9) Any one of the above items (1) to (8) may be constructed as follows: The determination unit performs the determination using a machine learning model generated by machine learning.

[0019] (10) Further aspects of the present invention are: A control method for a steel sheet processing apparatus that processes grooves on the surface of a steel sheet that is passed through in the direction of sheet passage, A laser irradiation step involves irradiating the surface with a laser beam from a laser irradiation unit to form grooves that are parallel or substantially parallel to the width direction of the steel plate, A lighting step in which pulsed light from the lighting unit is irradiated onto the groove, An imaging step to generate an image by imaging the groove irradiated with the pulsed light using an imaging unit for an exposure time longer than the irradiation time of the pulsed light, A determination step in which a determination unit makes a determination based on the captured image, A processing control step in which the operation of the laser irradiation unit is controlled by a processing control unit, It has, In the determination step, based on the captured image, it is determined whether the groove satisfies a first criterion relating to at least one of the depth and width of the groove. If the determination step determines that the groove does not meet the first criterion, the processing control step controls the laser irradiation unit so that the groove formed by the laser irradiation unit meets the first criterion.

[0020] (11) The above (10) may also be done as follows: When viewed in cross-section along the thickness direction of the steel plate, In the illumination step, the pulsed light is irradiated along the illumination optical axis which is on one side with respect to the normal to the surface of the steel plate. In the imaging step, imaging is performed along a first incident optical axis that is in a specular reflection position with respect to the illumination optical axis on the other side of the normal line, and imaging is performed along a second incident optical axis that is different from the specular reflection position.

[0021] (12) The following may also be done in (11) above: When the angle formed by the normal line and the illumination optical axis is θ L (°), the angle formed by the normal line and the first incident optical axis is θ C1 (°), and the angle formed by the normal line and the second incident optical axis is θ C2 (°), In the illumination step and the imaging step, the illumination optical axis, the first incident optical axis, and the second incident optical axis are set so as to satisfy the following formulas 1 to 3. θ C1 = -θ L ···(Formula 1) θ C2 = A - θ L ···(Formula 2) 60° ≤ A ≤ 120° ···(Formula 3)

[0022] (13) The following may also be done in (12) above: In the determination step, based on the captured image captured on the first incident optical axis and the captured image captured on the second incident optical axis, it is further determined whether the inclination angle of the side wall of the groove satisfies a second criterion. When it is determined in the determination step that the second criterion is not satisfied, in the processing control step, the laser irradiation unit is controlled so as to satisfy the second criterion in addition to the first criterion.

[0023] (14) The following may also be done in any one of (10) to (13) above: A time-lapse imaging step of acquiring a plurality of captured images of the groove passing through the same position in the plate width direction of the steel plate over time, A time-lapse change acquisition step of acquiring the time-lapse change in the shape of each groove passing through the same position based on each captured image obtained in the time-lapse imaging step. Based on whether the time-dependent changes obtained in the time-dependent change acquisition step meet the fourth criterion, a step is made to determine whether or not the laser irradiation unit needs to be adjusted. It further possesses.

[0024] (15) Any one of the above items (10) to (14) may be done as follows: The processing control step includes a step of removing protrusions formed in the groove using a removal unit located downstream of the laser irradiation unit in the direction of plate passage, In the determination step, in addition to determining the groove, it is also determined, based on the captured image, whether or not a third criterion, which is a criterion relating to at least one of the height and width of the protrusion, is met. If the determination step determines that the protrusion does not meet the third criterion, the processing control step removes the protrusion.

[0025] (16) The above (15) may also be done as follows: The illumination step, the imaging step, and the determination step are performed as follows: The position between the laser irradiation section and the removal section in the plate passing direction, A position downstream of the removal section in the direction of the passing plate, Each of these will be handled individually.

[0026] (17) Any one of the above items (10) to (15) may be done as follows: A tracking step to obtain the position of the groove and the position of the protrusion on the surface of the steel plate, A mapping step to create a map that includes groove information linking the position of the groove and the shape of the groove, and protrusion information linking the position of the protrusion and the shape of the protrusion, It further possesses.

[0027] (18) Further aspects of the present invention are: A control method for a steel sheet processing apparatus that processes grooves on the surface of a steel sheet that is passed through in the direction of sheet passage, A laser irradiation step involves irradiating the steel plate with a laser beam from a laser irradiation unit to form grooves that are parallel or substantially parallel to the width direction of the steel plate, A lighting step in which pulsed light from the lighting unit is irradiated onto the groove, An imaging step to generate an image by imaging the groove irradiated with the pulsed light using an imaging unit for an exposure time longer than the irradiation time of the pulsed light, A determination step in which a determination unit makes a determination based on the captured image, A removal step in which a protrusion formed in the groove is removed by a removal unit, It has, In the determination step, based on the captured image, it is determined whether or not a third criterion, which is a criterion relating to at least one of the height and width of the protrusion, is met. If the determination step determines that the protrusion does not meet the third criterion, the removal unit is controlled in the removal step to remove the protrusion.

[0028] (19) Any one of the above items (10) to (18) may be done as follows: The determination in the aforementioned determination step is performed using a machine learning model generated by machine learning. [Effects of the Invention]

[0029] According to each of the above embodiments of the present invention, even when the steel sheet is fed at a high speed, it is possible to generate an image that clearly captures the grooves formed on the surface of the steel sheet. Based on this image, it becomes possible to determine the state of the grooves, and based on this determination, feedback control related to groove processing can be performed, so that steel sheets with desired magnetic properties can be manufactured stably. [Brief explanation of the drawing]

[0030] [Figure 1] This is a flowchart illustrating the general control method for a steel sheet processing apparatus according to each embodiment of the present invention. [Figure 2]This is a perspective view showing the schematic configuration of a steel sheet processing apparatus according to the first embodiment of the present invention. [Figure 3] This is a timing chart showing the relationship between the exposure time by the imaging unit and the irradiation time by the illumination unit in the first embodiment. [Figure 4] This is a block diagram showing the schematic configuration of the steel sheet processing apparatus according to the first embodiment. [Figure 5] This figure shows the observation of the groove in the first embodiment. Here, (a) is a longitudinal cross-sectional view of the steel plate along the direction of plate passage. (b) is a figure showing the case where the groove is of an appropriate depth (dg = 25 μm), with the upper part of the paper being a longitudinal cross-sectional view of the groove and the lower part being a plan view of the groove. Furthermore, (c) is a figure showing the case where the groove is shallow (dg = 15 μm), with the upper part of the paper being a longitudinal cross-sectional view of the groove and the lower part being a plan view of the groove. [Figure 6] This is a photograph showing an example of the longitudinal cross-sectional shape of a groove. [Figure 7] (a) is a diagram showing the case in the first embodiment in which a good groove is formed, with the upper part of the paper showing a plan view of the steel plate and the lower part showing an image of the captured groove. (b) is a diagram showing the analysis results based on the captured image in (a). [Figure 8] Figure 7 is a graph illustrating the luminance analysis process using the captured image. Here, (a) shows the luminance distribution in the direction of plate passage, (b) shows the average luminance distribution in the direction of plate passage, and (c) shows the relationship between the luminance ratio I(Ag' / As') and groove depth. [Figure 9] (a) is a diagram showing the case in the first embodiment in which a poorly formed shallow groove is created, with the upper part of the paper showing a plan view of the steel plate and the lower part showing an image of the captured groove. (b) is a diagram showing the analysis results based on the captured image in (a). [Figure 10] Figure 9 is a graph illustrating the luminance analysis process using the captured image. Here, (a) shows the luminance distribution in the direction of plate passage, (b) shows the average luminance distribution in the direction of plate passage, and (c) shows the relationship between the luminance ratio I(Ag' / As') and groove depth. [Figure 11]This is a block diagram showing the schematic configuration of a steel sheet processing apparatus in a second embodiment of the present invention. [Figure 12] This is a block diagram showing the schematic configuration of a steel sheet processing apparatus in a third embodiment of the present invention. [Figure 13] This is an explanatory diagram of the machine learning process in the fourth embodiment of the present invention. Here, (a) shows a schematic diagram for explaining the learning process, and (b) shows a schematic diagram for explaining the inference process. [Figure 14] This figure shows a schematic configuration of a steel sheet processing apparatus according to a fifth embodiment of the present invention, and is a longitudinal cross-sectional view along the thickness direction of the steel sheet. [Figure 15] The figure shows the fifth embodiment in which good grooves (dg = 25 μm) are formed, where (a) is a longitudinal cross-sectional view of the steel plate, (b) is an image captured by camera 21a, and (c) is an image captured by camera 21b. [Figure 16] In the fifth embodiment, the figure shows a case where poorly formed shallow grooves (dg = 15 μm) are formed, where (a) is a longitudinal cross-sectional view of the steel plate, (b) is an image captured by camera 21a, and (c) is an image captured by camera 21b. [Figure 17] This is a diagram illustrating the fifth embodiment, and is a longitudinal cross-sectional view along the thickness direction of the steel plate. [Figure 18] This figure illustrates the fifth embodiment and is a graph showing the relationship between the groove side wall inclination angle and the iron loss improvement rate. [Figure 19] This figure illustrates the fifth embodiment and is a graph showing the relationship between the inclination angle of the groove's side wall and the rate of magnetic flux density degradation. [Figure 20] (a) shows the image captured by camera 21a, (b) shows the distribution of Re1 values ​​based on the image captured in (a), and (c) shows the image captured by camera 21b. [Figure 21] This graph shows the change in the Re2 value of the groove-side inclined portion in the image captured by camera 21b for each inclination angle θG. Here, A=80°, θL=50°, θC1=-50°, θC2=30°, θC1=-θL, and θC2=A-θL. [Figure 22] This figure illustrates a sixth embodiment of the present invention and is a block diagram showing a schematic configuration of a determination result mapping device. [Figure 23] This figure illustrates the sixth embodiment, and shows a map in which groove shape defects and protrusions are mapped along the entire length of the steel plate by a determination result mapping device. [Modes for carrying out the invention]

[0031] Hereinafter, various embodiments of the steel sheet processing apparatus and its control method of the present invention will be described with reference to the drawings. Before that, however, an overview of the control contents of the steel sheet processing apparatus will be explained using the flowchart in Figure 1.

[0032] (Overview of the control system for steel plate processing equipment) The steel sheet processing apparatus of this embodiment has the configuration described later and processes grooves on the surface of a steel sheet that is passed through in the sheet direction. The control method of this steel sheet processing apparatus includes a laser irradiation step (laser processing start) S1, an illumination step S2, an imaging step S3, a determination step S4, and a processing control step S5.

[0033] In the laser irradiation step S1, a laser beam from the laser irradiation unit is irradiated onto the surface of the steel plate to form grooves that are parallel or substantially parallel to the width direction of the steel plate. Specifically, multiple laser irradiation units are arranged in a line in the width direction above the surface of the steel plate as it passes along the plate-passing direction. A laser beam is then irradiated onto the surface of the steel plate from each of these laser irradiation units, forming multiple grooves. When the surface of the steel plate is viewed from above, each groove is straight, either parallel to the width direction of the plate or along a scanning direction intersecting the width direction of the plate.

[0034] In the illumination step S2 following the laser irradiation step S1, pulsed light from the illumination unit is irradiated onto the grooves of the steel plate. Specifically, pulsed light is emitted from an illumination unit located downstream of the laser irradiation unit in the direction of sheet metal passage, directed towards the grooves. At this time, the pulsed light is emitted onto the surface of the steel plate so that the grooves are included within the irradiation range. The pulsed light is short-lived and high-intensity, illuminating the grooves and their surroundings on the surface of the steel plate. If protrusions are formed on the surface of the steel plate as a result of groove formation, these protrusions are also illuminated by the pulsed light.

[0035] In the imaging step S3 following the illumination step S2, an image is generated by capturing the groove irradiated with pulsed light using the imaging unit for an exposure time longer than the irradiation time of the pulsed light. In other words, the imaging unit captures an image of the imaging range, including grooves and protrusions, illuminated by pulsed light from the laser irradiation unit. At this time, the exposure time of the imaging unit is made longer than the irradiation time of the pulsed light. More specifically, the exposure starts earlier than the start of pulsed light irradiation, and the exposure ends later than the end of pulsed light irradiation. As a result, an image is obtained in which nothing is captured during the time when pulsed light is not irradiated, while during the time when pulsed light is irradiated, an image is obtained in which the grooves and protrusions are illuminated by the pulsed light, and their uneven shapes are clearly shown by the intensity of the reflected light. In this case, as mentioned above, the pulsed light is short-lived and high-intensity light, so even if the steel plate passes at a high speed, a clear, blur-free still image can be obtained as the captured image.

[0036] In the determination step S4, which follows the imaging step S3, the determination unit makes a determination based on the acquired image. This determination is performed based on roughly three criteria. In other words, in step S4-1, it is determined, based on the captured image, whether or not the groove satisfies a first criterion relating to either the groove depth or width, or both. Furthermore, in step S4-2, it is determined, based on the captured image, whether or not the inclination angle of the groove's side wall meets the second criterion. Furthermore, in step S4-3, based on the captured image, it is determined whether the protrusions formed in the groove meet a third criterion regarding either their height or width, or both.

[0037] In the processing control step S5 following the determination step S4, the operation of the laser irradiation unit or the removal unit is controlled by the processing control unit based on the results of the above steps S4-1, S4-2, and S4-3. In other words, if it is determined in step S4-1 that the groove does not meet the first criterion regarding either the depth or width of the groove, or both, the processing control unit adjusts the laser irradiation unit in step S5-1. This adjustment ensures that any grooves newly formed after the adjustment meet the first criterion. Furthermore, if it is determined in step S4-2 that the inclination angle of the groove's side wall does not meet the second criterion, the processing control unit adjusts the laser irradiation unit in step S5-2. This adjustment ensures that any grooves newly formed after the adjustment meet the second criterion. Furthermore, if it is determined in step S4-3 that the protrusions formed in the groove do not meet the third criterion regarding either their height or width, or both, the processing control unit adjusts the removal section in step S5-3. This adjustment ensures that any protrusions passing through the adjustment section after the adjustment are properly removed, resulting in the third criterion being met.

[0038] Note that Figure 1 illustrates the case where all of processes S4-1, S4-2, and S4-3 are performed, but the process is not limited to this. It is also possible to perform only process S4-1, or to perform processes S4-1 and S4-2 and not process S4-3, or to perform only process S4-3. If such a change is made in the determination step S4, the necessity of performing processes S5-1, S5-2, and S5-3 in the processing control step S5 will also change accordingly.

[0039] (First Embodiment) Figure 2 is a schematic diagram showing the configuration of a steel sheet processing apparatus according to the first embodiment of the present invention. The steel sheet processing apparatus 100 is a device that processes grooves on the surface of a steel sheet 200 that is passed through it (for example, processing grooves for magnetic domain control in the case of an electrical steel sheet). Hereinafter, the width direction of the steel sheet 200 will be referred to as the X-axis direction, the direction in which the steel sheet 200 is passed through the apparatus will be referred to as the Y-axis direction, and the normal direction (thickness direction) of the surface of the steel sheet 200 will be referred to as the Z-axis direction. In this embodiment, various types of steel sheets can be used as the steel sheet 200 on which grooves are formed by the steel sheet processing apparatus 100, for example, heat dissipation steel sheets, laminated steel sheets, electrical steel sheets, and other types of steel sheets.

[0040] The steel plate processing apparatus 100 comprises a laser irradiation unit 1, an imaging unit 21, an illumination unit 22, and a calculation processing unit 3.

[0041] The laser irradiation unit 1 irradiates the surface of the steel plate 200, which is passed through the steel plate 200 in the Y-axis direction, from a position away from the surface of the steel plate 200 in the Z-axis direction, focusing the laser beam so that it forms a circular or elliptical spot of light on the surface of the steel plate 200, and scans the surface of the steel plate 200 in a direction substantially parallel to the plate width direction (X-axis direction), thereby performing groove processing to form grooves 201 extending in the plate width direction of the steel plate 200 on the surface of the steel plate 200. Note that the direction of extension of the grooves 201 in a plan view may be a direction intersecting the plate width direction.

[0042] The laser irradiation unit 1 repeatedly performs groove processing on the steel plate 200 being passed through it at regular time intervals, thereby forming a plurality of grooves 201 extending in the width direction of the plate on the surface of the steel plate 200 at regular distance intervals along the direction of passage. In the example shown in Figure 2, the direction in which the laser beam is scanned (scanning direction) is slightly inclined from the width direction of the steel plate 200 (a direction approximately parallel to the width direction of the steel plate 200), but the scanning direction and the width direction may be parallel.

[0043] The laser irradiation unit 1 comprises a laser output unit (not shown), a laser scanning unit (not shown), and a laser focusing unit (not shown). The laser output unit outputs a laser beam transmitted from a laser light source located outside the laser irradiation unit 1 to the laser scanning unit. The laser scanning unit is, for example, a rotating polygon mirror, which uses the rotating polygon mirror to scan the laser beam received from the laser output unit in a linear manner along a direction substantially parallel to the width direction of the steel plate 200. At this time, the laser beam output from the laser scanning unit is focused at a position on the surface of the steel plate 200 by the laser focusing unit, increasing its energy density so that the surface of the steel plate 200 can be melted and scattered. For example, an fθ lens can be used as the laser focusing unit.

[0044] Each time a scanning cycle is completed (one cycle is defined as the time it takes for the spot of the laser beam to move from the starting point to the ending point of the scan, and for the surface of the polygon mirror that the laser beam strikes to switch, causing the spot of the laser beam to return to the starting point of the scan), the laser irradiation unit 1 sends a signal to the synchronization unit 31, described later, located within the arithmetic processing unit 3, indicating the end of one scanning cycle.

[0045] Furthermore, a galvanometer mirror can be used instead of a polygon mirror as the laser scanning unit.

[0046] The imaging unit 21 and the illumination unit 22 are both positioned away from the surface of the steel plate 200 in the Z-axis direction, and downstream in the Y-axis direction in the plate-passing direction (downstream in the plate-passing direction) from the laser irradiation unit 1. The imaging unit 21 and the illumination unit 22 are positioned facing the groove 201 so that pulsed light from the illumination unit 22 is irradiated onto the groove 201 formed by the laser irradiation unit 1, and the imaging unit 21 images the groove 201 irradiated with pulsed light to obtain an image.

[0047] The imaging unit 21 obtains an image of the surface of the steel plate 200 and outputs the obtained image to the arithmetic processing unit 3, which will be described later. The exposure time Ti of the imaging unit 21 can be set to be variable. The imaging unit 21 can be realized using a CCD (Charge Coupled Device) camera or a CMOS (Complementary metal-oxide-semiconductor) camera. The imaging unit 21 may be capable of capturing monochrome images or color images.

[0048] The illumination unit 22 is an illumination device that irradiates pulsed light into the grooves 201 formed by the laser irradiation unit 1. That is, the illumination unit 22 irradiates pulsed light in accordance with the timing of the steel plate 200's passage through the grooves 201 formed on the surface of the steel plate 200.

[0049] In this embodiment, the illumination unit 22 uses, for example, a semiconductor laser with a wavelength of 640 [nm] to irradiate pulsed light for an irradiation time Tp (100 [ns] in this embodiment). The pulsed light irradiation time Tp is variable and can be adjusted, for example, in the range of 30 [ns] to 1000 [ns]. As described later, since the pulsed light irradiation time Tp is set to be shorter than the exposure time Ti by the imaging unit 21, an image of the groove 201 formed in the steel plate 200 being passed at high speed can be obtained.

[0050] The arithmetic processing unit 3 is a functional unit that performs various calculations related to the steel plate processing apparatus 100 and controls the operation of various functional units. For example, it is implemented by a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), communication device, etc. The arithmetic processing unit 3 mainly performs synchronization processing between the laser irradiation unit 1, the imaging unit 21 and the illumination unit 22, quality determination processing of the groove 201 using the image captured by the imaging unit 21, and processing control by the laser irradiation unit 1 based on the quality determination result.

[0051] Next, the relationship between the exposure time Ti by the imaging unit 21 and the pulsed light irradiation time Tp by the illumination unit 22 will be explained using Figure 3.

[0052] Figure 3 is a timing chart showing the relationship between exposure time Ti and irradiation time Tp. Figure 3(a) is a graph showing the exposure time Ti of the imaging unit 21 and the start and end timings of the exposure time Ti (imaging timing), and Figure 3(b) is a graph showing the irradiation time (pulse width) Tp of pulsed light by the illumination unit 22 and the start and end timings of the irradiation time Tp (irradiation timing).

[0053] As shown in Figure 3(a), the exposure time Ti of the imaging unit 21 is the time from the rising edge at the start timing (exposure start timing (T1)) to the falling edge at the end timing (exposure end timing (T3)). Also, as shown in Figure 3(b), the pulse light irradiation time Tp is the time from the rising edge at the start timing of irradiation (irradiation start timing (T2)) to the falling edge at the end timing of irradiation (irradiation end timing (T4)). As shown in Figure 3, the exposure time Ti of the imaging unit 21 is longer than the pulse light irradiation time Tp.

[0054] In this way, the imaging unit 21 images the grooves 201 irradiated with pulsed light with an exposure time longer than the irradiation time of the pulsed light. As a result, the imaging unit 21 generates an image by essentially imaging the grooves 201 formed in the steel sheet 200 at the moment the pulsed light is irradiated from the illumination unit 22, while keeping the shutter open for a long time, in which case no image is acquired due to the low ambient brightness. On the other hand, it acquires an image only at the moment when the ambient brightness increases instantaneously due to the irradiation of pulsed light.

[0055] The detailed control of the illumination unit 22 is as follows: At time T2, based on a signal received from the synchronization unit 31 (described later) indicating the timing at which the groove 201 formed on the steel plate 200 being passed reaches the imaging position of the imaging unit 21, the illumination unit 22 emits pulsed light (synchronized with the imaging unit 21) at the timing when the groove 201 formed on the steel plate 200 passes the imaging position of the imaging unit 21.

[0056] As a result, the illumination unit 22 can irradiate pulsed light at a constant repetition period such that each groove 201 formed at a constant distance interval along the direction of plate passage on the surface of the steel plate 200 passes approximately to the center of the imaging field of view of the imaging unit 21 as the plate passes through.

[0057] Furthermore, the distance Lp [m] traveled by the groove 201 moving in the direction of the plate at a plate speed VL [m / s] during the pulse light irradiation time Tp is given by the following equation 4. Since the travel distance Lp affects the blur of the image when the groove 201 is captured as a still image, it is preferable that it be as short as possible compared to the groove width. Therefore, the pulse light irradiation time Tp [s] is adjusted appropriately, taking into account the plate speed VL and the groove width of the groove 201 to be captured. Lp=VL×Tp … (Formula 4)

[0058] In this embodiment, for example, if the groove width formed is 50 to 100 [μm], the travel distance Lp is preferably 1 [μm] or less, and if the plate speed VL of the steel plate 200 is 2 [m / s], the pulse light irradiation time Tp is preferably 500 [ns] or less. In this embodiment, the pulse light irradiation time Tp is set to 100 [ns].

[0059] Furthermore, the determination of the quality of the groove 201 using the captured image described later is performed by comparing the situation when the surroundings are dimly lit with the situation when the surroundings are brightened by pulsed light. In this determination process, the determination of brightness, such as how bright or dark it is, can be appropriately changed by adjusting the sensitivity of the imaging unit 21. In addition, in order to make the image taken with pulsed light clearer, the brightness of the surroundings other than the pulsed light may be intentionally lowered.

[0060] Furthermore, the detailed control of the imaging unit 21 is as follows. At time T1, based on a signal received from the synchronization unit 31 (described later) indicating the timing at which the grooves 201 formed on the steel plate 200 being passed through reach the imaging position of the imaging unit 21, the imaging unit 21 performs imaging (synchronized with the illumination unit 22) at the timing when the grooves 201 formed on the steel plate 200 pass the imaging position of the imaging unit 21 (more precisely, imaging is performed so that the timing at which the grooves 201 formed on the steel plate 200 pass the imaging position of the imaging unit 21 is included in the exposure time range), and generates an image. As a result, the illumination unit 22 irradiates a spot light at the timing when the grooves 201 included in the exposure time of the imaging unit 21 pass approximately in the center of the imaging field of view of the imaging unit 21, making it possible to image the grooves 201 formed on the steel plate 200 at approximately the center position of the image captured by the imaging unit 21.

[0061] The imaging unit 21 preferably has a configuration that allows it to continuously capture 1,000 or more still images per second. The repetition frequency F [Hz] of imaging in the imaging unit 21 can be calculated using the following equation 5, where PL [mm] is the groove formation pitch and VL is the speed at which the steel plate 200 passes through. F = VL / PL [kHz] … (Equation 5)

[0062] In this embodiment, for example, if the speed VL of the steel plate 200 is 2 [m / s] and the groove formation pitch PL is 3 [mm], the imaging frequency will be approximately 667 [Hz]. Therefore, approximately 667 grooves 201 will pass through the imaging range of the imaging unit 21 in total per second. However, since the imaging unit 21 can continuously capture more than 1000 still images per second, it is possible to image all the grooves 201 that pass through the imaging range. When the speed VL of the steel plate 200 is high, an imaging unit 21 with a larger number of images that can be captured per second should be used. The imaging unit 21 may also be equipped with an optical telephoto function, and in this embodiment, one equipped with a telephoto function with a maximum optical magnification of 50x was used. Furthermore, when the speed VL of the steel plate 200 is 2 [m / s], the distance that the grooves 201 move within the pulse light irradiation time Tp (100 [ns]) is 0.2 [μm]. Since a travel distance of 0.2 [μm] is sufficiently small compared to a groove width of approximately 50 [μm], it is possible to clearly observe the groove 201 as a still image even when the groove 201, which has a minute groove width of approximately 50 [μm], is passing through the plate at high speed.

[0063] Figure 4 is a block diagram showing the configuration of the steel sheet processing apparatus 100 shown in Figure 2. As shown in Figure 4, the calculation processing unit 3 comprises a synchronization unit 31, a determination unit 32, and a processing control unit 33.

[0064] The synchronization unit 31 is connected to the laser irradiation unit 1, the imaging unit 21, and the illumination unit 22, and receives a signal from the laser irradiation unit 1 indicating the end of one scanning cycle. The synchronization unit 31 outputs a signal indicating the end of one scanning cycle to the imaging unit 21 and the illumination unit 22, thereby synchronizing the imaging timing in the imaging unit 21 and the pulse light irradiation timing by the illumination unit 22 with the timing when the formed groove 201 passes the imaging position. This allows the illumination unit 22 to irradiate pulse light at the timing when the groove 201 formed in the steel plate 200 passes the imaging position of the imaging unit 21, enabling the imaging unit 21 to image the groove 201.

[0065] The synchronization unit 31 determines the scanning cycles in which the grooves 201 are formed by the laser irradiation unit 1 using the encoder (rotational position detector) of the motor of the polygon mirror, which is the laser scanning unit of the laser irradiation unit 1. Then, based on the speed at which the steel plate 200 passes and the timing of the end of one scanning cycle, the synchronization unit 31 calculates the timing at which the grooves 201 formed on the passing steel plate 200 reach the imaging position of the imaging unit 21, and outputs a signal to the imaging unit 21 and the illumination unit 22 indicating the timing at which the grooves 201 formed on the steel plate 200 reach the imaging position of the imaging unit 21.

[0066] Furthermore, if a galvanometer mirror is used instead of a polygon mirror as the laser scanning unit, the rotation angle of the galvanometer motor can be detected by a rotation position detector to determine the timing of the end of one cycle.

[0067] The synchronization unit 31 synchronizes the imaging timing of the imaging unit 21 with the illumination timing of the illumination unit 22 so that the exposure time Ti in the imaging unit 21 and the pulse light irradiation time Tp in the illumination unit 22 overlap in time. As described above, since the exposure time of the imaging unit 21 is longer than the irradiation time of the illumination unit 22 (Ti > Tp), the grooves 201 of the steel plate 200 can be imaged only during the pulse light irradiation time by the illumination unit 22.

[0068] The determination unit 32 is connected to the imaging unit 21 and the processing control unit 33, and is a functional unit that acquires an image from the imaging unit 21 and makes a determination based on the image. For example, it performs a brightness analysis based on the image and determines whether the groove 201 satisfies a predetermined standard, which is a standard for at least one of the depth and width of the groove 201. That is, the determination unit 32 estimates the depth and width of the groove 201 based on the image generated by the imaging unit 21, and determines the quality of the groove 201 based on whether the estimated depth and width satisfy the predetermined standard values ​​that are set in advance as standards for the depth and width required for grooves for magnetic domain control. The determination unit 32 may also estimate at least one of the depth and width of the groove 201 and determine its quality.

[0069] Furthermore, when forming grooves 201 on the surface of the steel plate 200 using a laser beam, there is a risk that protrusions may form around the grooves 201 formed on the surface of the steel plate 200, such as protrusions created by the melting and re-solidification of the metal constituting the steel plate 200, or protrusions created by the fusion of scattered molten material to the surface of the steel plate 200. If such secondary protrusions (hereinafter referred to as protrusions) remain on the steel plate 200, for example, when stacking them to form a transformer core as in electrical steel sheets, they may damage the insulating film between overlapping steel plates 200, reducing electrical insulation and potentially degrading the performance of the transformer.

[0070] Therefore, the determination unit 32 may determine, based on the captured image, whether or not the protrusions generated in the groove 201 meet a predetermined standard, which is a standard for at least one of the height and width of the protrusions. That is, the determination unit 32 performs a brightness analysis based on the captured image generated by the imaging unit 21 to estimate the height and width of the protrusions generated along with the groove 201, and determines whether or not the protrusions should be removed based on whether or not the estimated height and width meet the predetermined standard values ​​that are set in advance as the standard for the height and width of protrusions that can be allowed when generating grooves for magnetic domain control. The determination unit 32 may also estimate only at least one of the height and width of the protrusions and determine whether or not it is acceptable.

[0071] In this embodiment, the laser beam scanned and irradiated onto the steel plate 200 in the laser irradiation unit 1 is, for example, a continuous-wave single-mode fiber laser with a wavelength of 1.07 [μm], a laser power of 2000 [W], a scanning speed Vs of 50 [m / s], a circular focusing shape, and a focused beam diameter d of φ20 [μm]. The speed VL of the steel plate 200 is 2 [m / s], and the groove formation pitch of the grooves 201 is 3 [mm]. In such a case, the determination unit 32 can determine that the predetermined criteria are met (i.e., the processing condition is good) if the grooves 201 formed on the steel plate 200 have a depth of 20 [μm] or more and a width of 50 [μm] or less.

[0072] The processing control unit 33 is connected to the laser irradiation unit 1 and the determination unit 32, and is a functional unit that controls the operation of the laser irradiation unit 1. For example, if it is determined that the groove 201 does not meet the predetermined criteria, the processing control unit 33 controls the laser irradiation unit 1 so that the groove 201 formed by the laser irradiation unit 1 thereafter meets the predetermined criteria. In other words, the processing control unit 33 controls the laser irradiation unit 1 based on the determination result by the determination unit 32. For example, if the determination unit 32 determines that the depth of the groove 201 formed on the surface of the steel plate 200 is less than a predetermined criterion value, the processing control unit 33 controls the laser irradiation unit 1 so that the groove 201 formed on the surface of the steel plate 200 is equal to or greater than the predetermined criterion value, and changes the settings of processing conditions such as the laser beam focus.

[0073] Furthermore, if the processing control unit 33 determines that the protrusions generated in conjunction with the creation of the grooves 201 do not meet a predetermined standard, it may control the removal unit to remove any protrusions that subsequently form in the grooves 201 created by the laser irradiation unit 1. That is, the processing control unit 33 controls the removal unit, which will be described later, based on the determination result by the determination unit 32. For example, if the determination unit 32 determines that the height of the protrusions generated in conjunction with the creation of the grooves 201 on the surface of the steel plate 200 is greater than or equal to a predetermined standard value, the processing control unit 33 controls the removal unit, which will be described later, to remove the protrusions so that the protrusions on the surface of the steel plate 200 are less than the predetermined standard value.

[0074] In this description, we have described a case where, if the determination unit 32 determines that the depth of the grooves 201 formed on the surface of the steel plate 200 is less than a predetermined standard value, the laser irradiation unit 1 is controlled so that the grooves 201 formed on the surface of the steel plate 200 become equal to or greater than a predetermined standard value. However, the present invention is not limited to this, and the scanning irradiation of the laser beam from the laser irradiation unit 1 may be stopped, or the steel plate processing apparatus 100 itself may be stopped.

[0075] Next, we will explain an estimation method for estimating the quality of a groove 201 formed in a steel plate 200 by imaging the groove 201 with the imaging unit 21 and performing brightness analysis on the obtained image, and a method for determining whether a groove 201 is a good groove 201 that meets a predetermined standard value using the estimation results.

[0076] In this embodiment, the arithmetic processing unit 3 performs brightness analysis within the captured image captured by the imaging unit 21 using the determination unit 32. In addition to determining the quality of the groove 201, it is also possible to determine the quality of the groove 201 by determining whether the protrusions meet predetermined criteria.

[0077] Figures 5(a), (b), and (c) schematically show the observation status of the groove 201. Figure 5(a) is a schematic diagram for explaining the positional relationship between the imaging unit 21 and the illumination unit 22 with respect to the groove 201 of the steel plate 200. Figure 5(a) is a cross-sectional view in the thickness direction as seen along the plate passage direction. The upper part of Figure 5(b) shows the cross-sectional configuration when a groove 201 deeper than a reference value is formed on the surface of the steel plate 200, and is a cross-sectional view in the thickness direction as seen along the plate passage direction. The lower part of Figure 5(b) schematically shows an image captured in a plan view of the upper part of Figure 5(b). The upper part of Figure 5(c) shows the cross-sectional configuration when a shallow groove 201 less than a reference value is formed on the surface of the steel plate 200, and is a cross-sectional view in the thickness direction as seen along the plate passage direction. The lower part of Figure 5(c) schematically shows an image captured in a plan view of the upper part of Figure 5(c). In Figures 5(a), (b), and (c), the direction from left to right is the direction of plate passage (Y-axis direction), and the direction from bottom to top is the Z-axis direction, which is the normal direction to the steel plate 200. Also, the direction from front to back of the paper is the plate width direction (X-axis direction).

[0078] Figure 6 shows a cross-sectional photograph corresponding to the schematic diagrams shown in the upper diagrams of Figure 5(b) and Figure 5(c). This cross-sectional photograph in Figure 6 shows grooves 201 formed on the surface of the steel plate 200. The protrusions created when the grooves 201 were formed by laser beam irradiation are also shown on the right side of the steel plate surface.

[0079] As shown in Figure 5(a), the imaging unit 21 is positioned such that at point P on the surface of the steel plate 200, the optical axis of the imaging unit 21 intersects with the steel plate 200, and the direction of specular reflection is relative to the central axis of the irradiation direction of the pulsed light emitted from the illumination unit 22. That is, the optical axis of the imaging unit 21 and the irradiation direction of the pulsed light emitted from the illumination unit 22 are positioned to form a predetermined angle θ with respect to the Z-axis direction when viewed from the X-axis direction.

[0080] As described later, in order to determine the depth of the grooves 201 formed on the surface of the steel plate 200, it is preferable that the imaging angle of the imaging unit 21 relative to the surface of the steel plate 200 and the irradiation angle of the pulsed light from the illumination unit 22 relative to the surface of the steel plate 200 be 5 degrees or more and 70 degrees or less with respect to the normal direction of the surface of the steel plate 200, and more preferably 20 degrees or more and 50 degrees or less.

[0081] As a result, as shown in Figure 5(b), if the groove 201 is deep, exceeding the reference value, much of the reflected light from the pulsed light reflected off the inner surface of the groove 201 does not go towards the imaging unit 21. Therefore, when the groove 201 is imaged by the imaging unit 21, the portion of the groove 201 appears dark in the captured image. In contrast, as shown in Figure 5(c), if the groove 201 is shallow, less than the reference value, much of the reflected light from the pulsed light reflected off the inner surface of the groove 201 goes towards the imaging unit 21. Therefore, when the groove 201 is imaged by the imaging unit 21, the portion of the groove 201 appears bright in the captured image. Thus, the depth and width of the groove 201 can be estimated by utilizing these differences in brightness (brightness / darkness) within the captured image.

[0082] In this way, the determination unit 32 performs brightness analysis on the captured image. Specifically, the determination unit 32 determines that dark, continuous band-shaped areas in the captured image are grooves 201, and determines that the areas with high brightness around them are protrusions. In the captured image, lumps of molten metal generated in the grooves 201 appear as high-brightness areas arranged in rows along the grooves 201. Therefore, the determination unit 32 performs brightness analysis using these brightness characteristics that appear in the captured image to estimate the presence or absence of lumps of molten metal in the grooves 201 and determine the quality of the grooves 201. The detailed processing of brightness analysis by the determination unit 32 will be explained below using Figures 7 to 10.

[0083] First, an example of a good groove 201 formed on the surface of a steel plate 200 will be described. Here, a predetermined standard value for the depth of a good groove 201 is set to 20 [μm] or more, and a groove 201 with a depth of 20 [μm] or more is determined to be a groove 201 with a good depth. The upper part of Figure 7(a) shows a schematic diagram of the surface of a steel plate 200 in which a good groove 201 with a depth of 25 [μm] has been formed. The lower part of Figure 7(a) shows an image IG1 obtained when pulsed light is irradiated from the illumination unit 22 onto the region of the surface of the steel plate 200 in which a good groove 201 has been formed, and the groove 201 irradiated with the pulsed light is captured by the imaging unit 21. Figure 7(b) is a schematic diagram showing the width (also simply called groove width) Wg of the groove 201 obtained from the image IG1 shown in Figure 7(a). In Figures 7(a) and (b), the vertical direction is the X-axis direction, and the horizontal direction is the Y-axis direction.

[0084] As shown in Figures 7(a) and (b), the quality of the depth of the grooves 201 formed in the steel plate 200 is determined by the determination unit 32, which performs brightness analysis using the captured image of the grooves 201 taken at the timing when pulsed light is irradiated. Based on the brightness and darkness in the captured image, the position, shape, and width Wg of the grooves 201 are estimated, and a determination is made based on the obtained estimation results.

[0085] Figure 8(a) shows the measurement results of luminance A measured along the white dotted line Li1 extending in the Y-axis direction, as shown in the captured image IG1 of Figure 7(a). The horizontal axis shows the position in the Y-axis direction, and the vertical axis shows the luminance A. Figure 8(a) also shows the moving average values ​​of these luminance A values ​​as a solid line.

[0086] In the captured image IG1, the unprocessed portion of the steel plate 200 surface where the grooves 201 are not formed has a relatively high brightness due to specular reflection of pulsed light, while the grooved portion where the grooves 201 are formed has a relatively low brightness because there is less reflection of pulsed light. Furthermore, in the captured image IG1, protrusions formed around the grooves 201 appear with even higher brightness due to their high surface gloss. Therefore, the determination unit 32 determines the surface of the steel plate 200 where the grooves 201 are not formed, the grooves 201, and the protrusions in the following manner.

[0087] First, the determination unit 32 estimates the portion where the brightness change value is 10% or less over a distance (e.g., 200 μm) sufficiently longer than the maximum design groove width (e.g., 100 μm), and defines that portion as the steel plate surface (unprocessed portion), and sets the average brightness of that portion as the steel plate surface brightness As. In Figure 8(a), the portion extending from the left and right ends towards the center is estimated to be the unprocessed portion, and its average value becomes the steel plate surface brightness As.

[0088] The determination unit 32 then sets a groove determination threshold brightness Ag to a brightness value that is a predetermined percentage lower (for example, 0.7 times or less) than the steel plate surface brightness As. The determination unit 32 estimates that grooves 201 are formed in a range where the brightness is less than or equal to the groove determination threshold brightness Ag. In Figure 8(a), the width of the groove 201 is shown as the groove width Wg.

[0089] Furthermore, the determination unit 32 defines a luminance value that is a predetermined percentage higher (for example, 1.2 times or more) than the steel plate surface luminance As as the protrusion determination threshold luminance Au. The determination unit 32 estimates that a protrusion is formed in a range where the luminance is equal to or greater than the protrusion determination threshold luminance Au. In Figure 8(a), the width of the protrusion is shown as the protrusion width Wu.

[0090] In this way, the determination unit 32 performs a brightness analysis along the Y-axis at a predetermined position in the X-axis direction of the image captured by the imaging unit 21, and can estimate the positions of the unprocessed surface, grooves 201, and protrusions of the steel plate 200. The ratio of the groove determination threshold brightness Ag and the protrusion determination threshold brightness Au to the steel plate surface brightness As may be appropriately changed depending on the sensitivity of the imaging unit 21 and the irradiation intensity of the pulsed light from the illumination unit 22.

[0091] Here, there is a possibility that shallow portions exist within the groove 201 where luminance analysis is performed. In this case, the luminance of the groove 201 portion calculated based on the captured image will not be a constant value but will change. Therefore, the determination unit 32 performs luminance analysis along the Y-axis at multiple positions in the X-axis direction of the captured image IG1, and calculates the average luminance A' obtained from the luminance analysis results at multiple positions in the X-axis direction for each Y-axis direction position. The determination unit 32 then determines that a groove 201 is provided in a location where the average luminance A' obtained at each Y-axis direction position is below the groove determination threshold luminance Ag. Note that in determining the presence or absence of protrusions, since protrusions occur in limited locations in the X-axis direction, the average luminance value for each Y-axis direction position is not calculated from the luminance obtained at multiple positions in the X-axis direction.

[0092] Figure 8(b) shows the average brightness A', which is calculated by averaging the brightness values ​​obtained along the Y-axis for each of several positions in the X-axis direction. Figure 8(b) also shows the position of the groove 201 in the Y-axis direction and the groove width Wg in the Y-axis direction, which are determined based on the brightness analysis results. The determination unit 32 determines that the width of the groove 201 is good if the groove width Wg is within, for example, ±10% of the reference value of the groove width (for example, 50 [μm]). Note that the position of the groove 201 in the Y-axis direction and the groove width Wg shown in Figure 8(b) correspond to Figure 7(b).

[0093] Furthermore, the determination unit 32 determines the average value Ag' of luminance at the groove width Wg and the average value As' of luminance at the unprocessed portion of the surface of the steel plate 200 where the groove 201 is not formed (hereinafter simply referred to as "non-groove 201"). Based on this, the determination unit 32 can identify the groove 201 and the non-groove 201 portions of the steel plate 200 in the captured image, based on the change in luminance distribution in the width direction of the steel plate 200. The determination unit 32 then determines the luminance ratio I(Ag' / As'), which is the ratio of the average value Ag' of luminance at the groove width Wg to the average value As' of luminance at non-groove 201 portions.

[0094] Figure 8(c) is a graph showing the relationship between groove depth dg and luminance ratio I, with the luminance ratio I on the horizontal axis and groove depth dg on the vertical axis. Figure 8(c) shows the correlation between groove depth dg and luminance ratio I obtained in advance as a solid line. The deeper the groove 201, the lower the luminance in the captured image, and the lower the luminance ratio I of Ag' to As'. Therefore, if the luminance ratio I is small, it can be determined that the groove depth dg is large (deep), and if the luminance ratio I is large (I is close to 1), it can be determined that the groove depth dg is small (shallow).

[0095] Figure 8(c) shows the threshold luminance ratio It, which corresponds to the reference value of groove depth dt (e.g., 20 [μm]). The determination unit 32 compares the luminance ratio I obtained from the captured image with the threshold luminance ratio It. As shown in this example, if the luminance ratio I is smaller than the threshold luminance ratio It, it can be determined that the groove depth dg of the groove 201 is larger (deeper) than the desired groove depth dt, and therefore a groove 201 of good depth has been formed.

[0096] Next, we will describe an example in which poor grooves 201 are formed on the surface of the steel plate 200. The upper part of Figure 9(a) shows a schematic diagram of the surface of the steel plate 200 in which poor grooves 201 with a depth of 15 [μm], which is less than the standard value of 20 [μm], are formed. The lower part of Figure 9(a) shows the captured image IG2 when pulsed light is irradiated from the illumination unit 22 onto the region of the surface of the steel plate 200 in which the poor grooves 201 are formed, and the grooves 201 irradiated with the pulsed light are captured by the imaging unit 21.

[0097] Figure 9(b) is a schematic diagram showing the width (groove width) Wg of groove 201, obtained from the image IG2 shown in Figure 9(a). In Figures 9(a) and (b), the vertical direction is the X-axis and the horizontal direction is the Y-axis, similar to Figures 7(a) and (b).

[0098] Figure 10(a) shows the measurement results of luminance A measured along the dotted line Li2 extending in the Y-axis direction, as shown in the captured image IG2 of Figure 9(a). The horizontal axis shows the position in the Y-axis direction, and the vertical axis shows the luminance A. As with Figure 8(a), the moving average values ​​of these luminance A values ​​are shown as solid lines in Figure 10(a).

[0099] The determination unit 32 performs a brightness analysis based on the captured image IG2 to determine the steel plate surface brightness As, the groove determination threshold brightness Ag, and the steel plate surface brightness As. Then, by comparing these brightness levels with the brightness levels in the captured image IG2, it determines the surface of the steel plate 200, the grooves 201, and the protrusions. In this example, compared to the examples in Figures 7 and 8 described above, the groove depth dg of the grooves 201 is shallower, the groove width Wg is wider, and no protrusions are formed.

[0100] Figure 10(b) shows the average brightness A' obtained by averaging the brightness values ​​obtained along the Y-axis for each of the multiple positions in the X-axis direction in the captured image IG2. As shown in Figure 10(b), the determination unit 32 calculates the average brightness Ag' within the groove width Wg and the average brightness As' outside the groove 201 based on the average brightness A' obtained by averaging for each position in the Y-axis direction, as described above. Note that because the groove 201 is relatively shallow, the average brightness Ag' within the groove width Wg is smaller than the average brightness Ag' in the good example in Figure 8(b). The determination unit 32 uses the average brightness Ag' within the groove width Wg and the average brightness As' outside the groove 201 to determine the brightness ratio I.

[0101] As shown in Figure 8(c), when comparing the luminance ratio I with the threshold luminance ratio It, the luminance ratio I is greater than the threshold luminance ratio It. Therefore, the determination unit 32 estimates that the groove depth dg of the groove 201 is smaller (shallower) than the desired groove depth dt, and that a groove 201 of a suitable depth has not been formed. This is the conclusion.

[0102] By performing this image analysis, the determination unit 32 can determine whether the depth and width of the grooves 201 formed by the laser irradiation unit 1 are of good or bad quality. Furthermore, as shown in the upper part of Figure 8(a), the determination unit 32 can also identify the position of the protrusions formed on the steel plate 200 and the size of the protrusions (protrusion width Wu).

[0103] When the processing control unit 33 receives a determination result from the determination unit 32 indicating that the depth and width of the grooves 201 formed on the surface of the steel plate 200 do not meet the standard values, it controls the laser irradiation unit 1 based on the determination result so that the depth and width of the grooves 201 meet the standard values ​​and changes the settings of the processing conditions of the laser irradiation unit 1. Also, when the processing control unit 33 receives a determination result from the determination unit 32 indicating that a protrusion exceeding the standard height is generated on the steel plate 200, it controls the laser irradiation unit 1 based on the determination result so that no protrusion is generated in the grooves 201 and changes the settings of the processing conditions of the laser irradiation unit 1. For example, the processing control unit 33 sends an up-and-down control signal to the drive device that moves the fθ lens, which is a focusing element in the laser irradiation unit 1, up and down the focus, performs a groove depth determination each time, and performs focus adjustment until it becomes normal.

[0104] With this configuration of the first embodiment, the steel sheet processing apparatus 100 synchronizes the imaging timing of the imaging unit 21 imaging the grooves 201 with the irradiation timing of the pulsed light from the illumination unit 22 using the synchronization unit 31, so that the imaging unit 21 can image the grooves 201 on the surface of the steel sheet 200 being conveyed at a predetermined speed. As a result, the steel sheet processing apparatus 100 can determine whether the depth of the grooves 201 formed in the steel sheet 200 meets a reference value using the image captured by the imaging unit 21, without using a sensor to measure leakage magnetic flux as in the conventional method, while the steel sheet 200 is being conveyed at a predetermined speed. As a result, even when the steel sheet 200 is passed at high speed and grooves 201 are formed, it is possible to reliably obtain an image in which the grooves 201 are clearly captured.

[0105] Furthermore, the processing control unit 33 controls the laser irradiation unit 1 based on the determination result of the determination unit 32 so that grooves 201 with a depth and width that meet predetermined criteria are formed. As a result, steel plates 200 in a good processed state can be stably obtained while transporting the steel plates at a predetermined plate speed. In addition, since an image can be acquired at the time the grooves 201 are formed, quality control of the steel plates 200 becomes easier.

[0106] (Second Embodiment) In the second embodiment, an example is described in which a removal unit for removing protrusions is further provided. In the second embodiment as well, the processing control unit 33 controls the laser irradiation unit 1 so that grooves 201 with a depth and width that meet predetermined criteria are formed on the surface of the steel plate 200 based on the determination result of the determination unit 32, just as in the first embodiment described above. Therefore, this explanation will be omitted here, and the differences from the first embodiment will be described below.

[0107] Figure 11 is a block diagram showing the configuration of the steel sheet processing apparatus 100 according to the second embodiment. The removal section is a functional section that has the function of removing protrusions generated in the groove 201. In this embodiment, for example, a brush roll 41 and a support roll 42 are provided as the removal section.

[0108] In this embodiment, a brush control unit 43 is provided in the arithmetic processing unit 3b as the removal unit, and a brush roll 41 and a support roll 42 are provided that are linked to the brush control unit 43, which is different from the first embodiment shown in Figure 2.

[0109] As shown in Figure 11, in the steel sheet processing apparatus 100 according to the second embodiment, the brush roll 41 and the support roll 42 are positioned downstream of the laser irradiation unit 1 in the sheet feeding direction, and upstream of the imaging position of the imaging unit 21 in the sheet feeding direction.

[0110] The brush roll 41 is positioned opposite the support roll 42, and the steel plate 200 passes between the brush roll 41 and the support roll 42. The brush roll 41 is provided on the surface side of the steel plate 200, where a laser beam is irradiated by the laser irradiation unit 1 to form grooves 201. The brush roll 41 rotates as the steel plate 200 passes between the brush roll 41 and the support roll 42, and the brushes (not shown) provided on its outer circumference remove protrusions formed on the surface of the steel plate 200.

[0111] The brush roll 41 is configured to move vertically in the direction normal to the surface of the steel plate 200, and its position in this direction can be controlled by the brush control unit 43. The rotational speed of the brush roll 41 can also be controlled by the brush control unit 43. When the brush roll 41 is moved in a direction closer to the surface of the steel plate 200 under the control of the brush control unit 43, many protrusions can be removed by the brushes provided on its outer surface. However, if it gets too close to the surface of the steel plate 200, there is a risk of unintended damage to the steel plate 200. Therefore, the brush control unit 43 needs to control the position of the brush roll 41 so that the protrusions formed on the surface of the steel plate 200 are sufficiently removed by the brush roll 41, and so that the rotation of the brush roll 41 does not cause damage to the surface or grooves 201 of the steel plate 200.

[0112] Here, unlike grooves 201 which are formed along the width direction (Y-axis direction), the protrusions formed on the surface of the steel plate 200 are formed at specific locations on the surface of the steel plate 200. Therefore, the determination unit 32 does not use the average value of the brightness analysis results at multiple X-axis positions of the captured images for each Y-axis position, as is done for the determination of grooves 201, but rather detects the protrusions by the brightness analysis result along the Y-axis at a certain X-axis position.

[0113] In detail, as shown in the upper diagram of Figure 8, the determination unit 32 performs a luminance analysis along the plate-passing direction (Y-axis direction) at a predetermined position in the plate width direction (X-axis direction) within the captured image, and determines that a protrusion is formed in a range where the luminance is greater than or equal to the protrusion determination threshold luminance Au. The determination unit 32 then determines the width of the protrusion in the plate-passing direction determined based on the captured image as the protrusion width Wu, based on the range where the luminance is greater than or equal to the protrusion determination threshold luminance Au. Furthermore, the determination unit 32 determines the average luminance Au' at the protrusion width Wu based on the captured image, and calculates the average value As' of the surface luminance of the steel plate 200 based on the luminance of the steel plate 200 at positions other than the protrusion width Wu and groove width Wg.

[0114] The determination unit 32 then calculates the luminance ratio I = Au' / As', which is the ratio of the average luminance Au' at the protrusion width Wu to the average luminance As' of the surface luminance of the steel plate 200. The determination unit 32 has previously stored reference information showing the correlation between the height of the protrusion and the luminance ratio I, and can determine the height of the protrusion using the correlation shown in the reference information and the calculated luminance ratio I.

[0115] If the brush control unit 43 determines that the height of the protrusion does not meet the standard value (is higher than the standard value) as determined by the determination unit 32, it determines that the brush roll 41 has not sufficiently removed the protrusion and controls the brush roll 41 to move it toward the support roll 42. As a result, the brush roll 41 moves toward the surface of the steel plate 200, increasing the amount of protrusion removal and reducing the amount of protrusion formed on the steel plate 200.

[0116] Thus, in the steel sheet processing apparatus 100 according to the second embodiment, the determination unit 32 can directly determine whether the height of the protrusions, in addition to the grooves 201 formed on the steel sheet 200, meets the standard value. Furthermore, in the steel sheet processing apparatus 100 according to the second embodiment, the brush control unit 43 is also controllable in addition to the processing control unit 33 based on the result of the determination unit 32. Therefore, it is possible to suppress the formation of good grooves and the generation of protrusions that do not meet the standard on the steel sheet 200, thereby stably obtaining a steel sheet 200 with an even better processing condition.

[0117] (Third embodiment) In the second embodiment described above, the state of grooves 201 and protrusions on the surface of the steel plate 200 is determined based on an image captured by a single imaging unit 21, and the laser irradiation unit 1 and the brush roll 41 are controlled based on the obtained determination result. However, the present invention is not limited to this. For example, as shown in Figure 12, the steel plate processing apparatus 100 according to the third embodiment may be provided with an imaging unit 54 and an illumination unit 55 that acquire images for controlling the brush roll 41, in addition to the imaging unit 21 and illumination unit 22 that acquire images for controlling the laser irradiation unit 1.

[0118] As shown in Figure 12, the steel sheet processing apparatus 100 according to the third embodiment is provided with a synchronization unit 31, a first determination unit 32, a processing control unit 33, a brush control unit 43, and a second determination unit 56 in the calculation processing unit 3c. In addition, the steel sheet processing apparatus 100 is provided with an imaging unit 21 and an illumination unit 22 downstream of the laser irradiation unit 1 in the sheet feeding direction and upstream of the brush roll 41 in the sheet feeding direction, and furthermore, another imaging unit 54 and an illumination unit 55 are provided downstream of the brush roll 41 in the sheet feeding direction.

[0119] In this example, the synchronization unit 31 uses the distance L1 from the irradiation position of the laser beam of the laser irradiation unit 1 to the imaging position of the imaging unit 21 to synchronize the exposure start timing (imaging timing) of the imaging unit 21 with the irradiation timing of the pulsed light of the illumination unit 22. At the moment when the groove 201 formed in the steel plate 200 passes the imaging position of the imaging unit 21, the illumination unit 22 irradiates the groove 201 of the steel plate 200 with pulsed light, and the imaging unit 21 images the groove 201 that has been irradiated with the pulsed light.

[0120] In the steel sheet processing apparatus 100 according to the third embodiment, similar to the first embodiment described above, the first determination unit 32 determines the quality of the depth and width of the grooves 201 formed by the laser irradiation unit 1 based on the image captured by the imaging unit 21. Then, the steel sheet processing apparatus 100 controls the laser irradiation unit 1 with the processing control unit 33 based on the determination result obtained by the first determination unit 32, thereby stably obtaining steel sheets 200 in a good processed state while transporting the steel sheets 200 at a predetermined speed.

[0121] In this example, the synchronization unit 31 uses the distance L2 from the irradiation position of the laser beam of the laser irradiation unit 1 to the steel plate 200 to the imaging position of another imaging unit 54 to synchronize the exposure start timing (imaging timing) of the imaging unit 54 with the irradiation timing of the pulsed light of the illumination unit 55 which is paired with the imaging unit 54. At the moment when the groove 201 formed in the steel plate 200 passes the imaging position of the imaging unit 54, the illumination unit 55 irradiates the groove 201 of the steel plate 200 with pulsed light, and the imaging unit 54 images the groove 201 that has been irradiated with the pulsed light.

[0122] In the steel sheet processing apparatus 100, similar to the second embodiment described above, the second determination unit 56 determines, based on the image captured by the imaging unit 54, whether or not protrusions are formed around the grooves 201 of the steel sheet 200, and whether or not the height of the formed protrusions meets a standard value (whether or not it is higher than the standard value). Based on the determination result of the second determination unit 56, the steel sheet processing apparatus 100 controls the brush roll 41 with the brush control unit 43, and removes the protrusions of the steel sheet 200 by the brush roll 41 as the steel sheet 200 passes between the brush roll 41 and the support roll 42.

[0123] In addition, the steel sheet processing apparatus 100 according to the third embodiment outputs the determination result of the first determination unit 32 and the determination result of the second determination unit 56 to the brush control unit 43, and has a configuration that allows comparison between the determination result of the first determination unit 32 and the determination result of the second determination unit 56. As a result, the steel sheet processing apparatus 100 can observe the surface condition of the steel sheet 200, including the protrusions and grooves 201, before and after the protrusion removal process by the brush roll 41. Therefore, it is possible to determine not only whether the removal of protrusions by the brush roll 41 is sufficient, but also whether scratches have occurred on the surface of the steel sheet 200 by the brush roll 41.

[0124] With this configuration of the third embodiment, the processing control unit 33 controls the laser irradiation unit 1 so that grooves 201 with a depth and width that meet predetermined criteria are formed on the surface of the steel plate 200 based on the determination result obtained by the first determination unit 32, without measuring the leakage magnetic flux. At the same time, the brush control unit 43 controls the brush roll 41 so that protrusions that do not meet predetermined criteria are removed based on the determination result obtained by the second determination unit 56. As a result, the steel plate processing apparatus 100 according to the third embodiment can also stably obtain steel plates 200 in a good processed state while transporting the steel plate 200 at a predetermined feed speed, similar to the first and second embodiments described above.

[0125] Furthermore, in the steel sheet processing apparatus according to the third embodiment, by comparing the judgment results from the two first judgment units 32 and the second judgment unit 56, it is possible to determine whether the steel sheet 200 is in good condition based on the surface condition of the steel sheet 200 before and after the brush roll 41. Based on this judgment result, the brush roll 41 can be appropriately controlled, and any protrusions that do not meet the criteria can be removed by the brush roll 41, so that a steel sheet 200 in good processing condition can be stably obtained while conveying the steel sheet 200 at a predetermined feed speed.

[0126] (Fourth Embodiment) In the fourth embodiment, unlike the method for determining the quality of grooves 201 formed on the surface of the steel plate 200 described in the first embodiment, a method for determining the quality of grooves 201 formed on the surface of the steel plate 200 using machine learning will be described.

[0127] Figures 13(a) and 13(b) illustrate the machine learning model provided by the determination unit 32 of this embodiment. Figure 13(a) shows a schematic diagram for explaining the learning process, and Figure 13(b) shows a schematic diagram for explaining the inference process. In this learning and inference process, the captured image is taken as input, and the output is a determination result that determines the depth and width of the groove 201 and the size of the protrusions, and a determination result that determines the focal position of the laser irradiation unit 1.

[0128] In the learning process shown in the figure above, the learning unit 62 uses multiple training images pre-stored in the database 61 as input to perform machine learning, and generates a machine learning model 63 that outputs a determination result that determines the depth and width of the groove 201 and the size of the protrusions, as well as a determination result that determines the focal position of the laser irradiation unit 1, based on the captured images. When training an untrained machine learning model, there are unsupervised learning and supervised learning methods.

[0129] In the learning process, when supervising an untrained machine learning model, for example, multiple training images of grooves 201 and protrusions of a steel plate 200, training measurement results obtained by actually measuring the depth and width of the grooves 201 and the height of the protrusions in each training image, and a correct label indicating whether the training measurement result is the desired result (for example, an accuracy rate indicating whether the groove 201 is in the desired state) are used. When training the untrained machine learning model with multiple training images and the corresponding training measurement results, the correct label is attached and training is performed to generate a trained machine learning model 63.

[0130] In the learning process, when performing unsupervised learning on an untrained machine learning model, multiple training images of grooves 201 and protrusions of the steel plate 200, and training judgment results that determine the depth and width of the grooves 201 and the height of the protrusions in each training image are used to learn patterns and features from the multiple training images and their corresponding training judgment results, thereby generating a trained machine learning model 63.

[0131] For example, in the learning process, when training an untrained machine learning model using supervised learning, a multi-layer convolutional neural network (deep learning) can be used.

[0132] In the inference process shown in Figure 13(b), while the steel plate processing apparatus 100 is transporting the steel plate 200 and performing groove processing on its surface, the determination unit 32 performs inference processing using a trained machine learning model 63 with the captured image obtained from the imaging unit 21 as input. Based on the captured image, the determination unit can obtain a determination result that determines the depth and width of the groove 201 and the size of the protrusion, as well as a determination result that determines the focal position of the laser irradiation unit 1.

[0133] In this case, the determination unit 32 includes an inference unit 321 that performs inference processing using a trained machine learning model 63 generated by the learning process. The inference unit 321 outputs a determination result that determines the depth and width of the groove 201 and the size of the protrusions, and a determination result that determines the focal position of the laser irradiation unit 1, based on the captured image acquired from the imaging unit 21.

[0134] The following section describes in detail the training and inference processes for generating a trained machine learning model 63, using an example of determining the focal length of a laser beam scanned onto a steel plate 200. Here, we will explain an example of training an untrained machine learning model using supervised learning with deep learning.

[0135] Prior to the learning process shown in the figure above, the focal length of the laser beam irradiated from the laser irradiation unit 1 is controlled to change the focus of the laser beam on the surface of the steel plate 200, and the grooves 201 formed are imaged to prepare multiple learning images. For example, using the steel plate processing apparatus 100 shown in Figure 2, the focal position of the laser beam irradiated from the laser irradiation unit 1 is set to be above the steel plate 200, and grooves 201 are formed on the surface of the steel plate 200 when the laser beam is not focused on the surface of the steel plate 200. Then, pulsed light is irradiated from the illumination unit 22 onto the grooves 201 of the transported steel plate 200, and at the moment the pulsed light irradiates the grooves 201, the grooves 201 are imaged by the imaging unit 21 to acquire learning images.

[0136] Furthermore, in order to obtain other learning images, the focal position of the laser beam emitted from the laser irradiation unit 1 is aligned with the surface of the steel plate 200 to form grooves 201 on the surface of the steel plate 200 in an optimal state. Then, pulsed light is irradiated onto the grooves 201 of the transported steel plate 200 from the illumination unit 22, and at the moment the pulsed light irradiates the grooves 201, the grooves 201 are imaged by the imaging unit 21 to obtain other learning images.

[0137] Furthermore, in order to obtain other learning images, the focal position of the laser beam emitted from the laser irradiation unit 1 is aligned with the inside of the steel plate 200, and grooves 201 are formed on the surface of the steel plate 200 while the laser beam is not in focus on the surface of the steel plate 200. Then, pulsed light is irradiated onto the grooves 201 of the transported steel plate 200 from the illumination unit 22, and at the moment the pulsed light irradiates the grooves 201, the grooves 201 are imaged by the imaging unit 21 to acquire learning images. In this way, when the focal position of the laser beam scanned and emitted from the laser irradiation unit 1 is changed, multiple types of learning images are acquired, each capturing the grooves 201 formed on the surface of the steel plate 200.

[0138] Furthermore, for each of these training images, a training measurement result indicating the distance of the focal point from the steel plate 200, or a correct label indicating that the focus is good when the focal point of the laser beam is within a predetermined distance above or below the steel plate 200, and poor when the focal point is otherwise, is assigned. In this case, for each of these training images, training measurement results obtained by actually measuring the depth and width of the grooves 201 formed on the surface of the steel plate 200, as well as the height of the protrusions, etc., using an electron microscope or the like, may also be assigned.

[0139] The learning unit 62 uses multiple training images stored in the database 61 and corresponding training measurement results to assign correct labels to an untrained machine learning model using deep learning, thereby generating a machine learning model 63.

[0140] The inference unit 321, while the steel plate processing apparatus 100 is actually performing groove processing on the steel plate 200, uses the trained machine learning model 63 generated by the learning unit 62 as described above to estimate the focus deviation of the laser irradiation unit 1, the depth and width of the grooves 201 formed in the steel plate 200, and the presence or absence of protrusions, and can determine whether the processing is good or bad. Specifically, in the steel plate processing apparatus 100, while the steel plate 200 is being transported and groove processing is being performed on its surface, pulsed light is irradiated onto the grooves 201 of the transported steel plate 200 from the illumination unit 22, and at the moment the pulsed light is irradiated onto the grooves 201, the grooves 201 are imaged by the imaging unit 21 to acquire an image. The inference unit 321 receives the acquired image and inputs the image into the trained machine learning model 63 to output a judgment result that estimates the focus deviation of the laser irradiation unit 1, the depth and width of the grooves 201 formed in the steel plate 200, and the presence or absence of protrusions, as well as a judgment result that determines whether the processing is good or bad.

[0141] The steel sheet processing apparatus 100 can change the settings of the processing conditions of the laser irradiation unit 1 or change the position and rotation speed of the brush roll 41 based on the determination results obtained from the inference unit 321. As a result, it is possible to stably obtain steel sheets 200 in a good processed state while transporting the steel sheets 200 at a predetermined speed.

[0142] (Fifth embodiment) A fifth embodiment of the present invention will be described below with reference to Figures 14 to 23. Figure 14 is a schematic diagram showing the configuration of the steel sheet processing apparatus in this fifth embodiment, and is a longitudinal cross-sectional view along the thickness direction of the steel sheet 200. As shown in Figure 14, the steel sheet processing apparatus 100 of this embodiment differs from the configuration of the first embodiment described in Figure 2 in that it has two imaging units 21 instead of one, and the incident optical axes of each unit are different from those of the other.

[0143] In other words, the imaging unit 21 of this embodiment is composed of a camera 21a installed at a specular reflection position and a camera 21b installed at a diffuse reflection position, with the Z direction, which is the normal direction of the steel plate surface, as the axis of symmetry. Camera 21a captures an image for determining the depth and width of the groove 201. Camera 21b increases the intensity of reflected light from the side walls of the groove 201, so the brightness of the reflected light from the side walls is higher compared to when imaging is performed at the position of camera 21a.

[0144] Figure 15 illustrates a case where a good groove 201 is formed. Figure 15 shows a groove 201 with a groove depth of 25 μm (dg = 25 μm), where (a) is a longitudinal cross-sectional view along the direction of passage of the steel plate 200, (b) is an image captured by camera 21a, and (c) is an image captured by camera 21b. In Figure 15(a), the irradiation optical axis of the spot light from the illumination unit 22 is indicated by the symbol L1, the incident optical axis (first incident optical axis) reflected by the steel plate 200 and heading toward camera 21a is indicated by the symbol L2, and the incident optical axis (first incident optical axis) reflected by the steel plate 200 and heading toward camera 21b is also indicated by the symbol L2.

[0145] Figure 16 illustrates a case where a poorly formed, shallow groove 201 is created. Figure 15 shows a groove 201 with a groove depth of 15 μm (dg = 15 μm), where (a) is a longitudinal cross-sectional view along the direction of passage of the steel plate 200, (b) is an image captured by camera 21a, and (c) is an image captured by camera 21b. In Figure 16(a), the irradiation optical axis of the spot light from the illumination unit 22 is indicated by the symbol L1, the incident optical axis (first incident optical axis) reflected by the steel plate 200 and heading toward camera 21a is indicated by the symbol L2, and the incident optical axis (first incident optical axis) reflected by the steel plate 200 and heading toward camera 21b is also indicated by the symbol L2.

[0146] When comparing Figure 15(b) and Figure 16(b), although the arrangement of the illumination unit 22 and cameras 21a and 21b is the same, the difference in the depth of the groove 201 is reflected in the captured image as a difference in brightness distribution. In other words, when comparing Figure 15(b) and Figure 16(b), Figure 15(b), where the groove 201 is deeper, appears darker (more saturated) than Figure 16(b), where the groove 201 is shallower.

[0147] Furthermore, when comparing Figure 15(b) and Figure 15(c), although both images capture the same groove 201 illuminated by the same illumination optical axis L1, the overall brightness of the groove 201, including its side walls, differs due to the difference in the arrangement of cameras 21a and 21b (difference in incident optical axes L2 and L3). Similarly, when comparing Figure 16(b) and Figure 16(c), although both images capture the same groove 201 illuminated by the same illumination axis L1, the overall brightness of the groove 201, including its side walls, differs due to the difference in the arrangement of cameras 21a and 21b (differences in incident optical axes L2 and L3).

[0148] As can be seen from the results above, in this embodiment, by using two cameras 21a and 21b with different incident optical axes L2 and L3 to acquire two images, it is possible to obtain not only the depth and width of the groove 201, but also the inclination angle of the side wall surface of the groove 201. This point will be explained using Figures 17 and onward. Figure 17 is a longitudinal cross-sectional view of the steel plate 200 along the direction of plate passage and the thickness direction.

[0149] In the cross-section shown in Figure 17, the angle between the tangent line at the side wall surface of groove 201 and the direction of plate passage is θ. G Let (°) be the angle between the thickness direction (Z direction) of the steel plate 200 at the position of the side wall surface of the groove 201 and the incident optical axis L3 of the camera 21b. C2 Let (°) be the angle that the illumination optical axis L1 makes with respect to the thickness direction (Z direction) of the steel plate 200. L Let (°) be the angle between the incident optical axis L2 of the camera 21a and the thickness direction (Z direction) of the steel plate 200, which is θ. C1 Let's use (°).

[0150] When performing magnetic domain control by forming grooves 201 on the surface of a steel plate 200, in addition to the groove depth and width, the inclination angle θ of the side wall surface in the cross-sectional shape of the groove 201 is important. G (°) also affects iron loss and magnetic flux density. The ratio of the reduction in iron loss of the steel plate 200 after forming the groove 201 to the iron loss of the steel plate 200 before forming the groove 201 is defined as the iron loss improvement rate (%). In this case, the inclination angle θ of the side wall surface is defined as follows. G The relationship between the angle of inclination (°) and the iron loss improvement rate (%) is shown in Figure 18. As shown in Figure 18, G When the angle of inclination θ is small, the rate of improvement in iron loss is small, while the inclination angle θ is small. G When the angle exceeds a certain level, the rate of improvement in iron loss increases significantly.

[0151] On the other hand, as shown in Figure 19, the inclination angle θ G As the angle approaches 90°, the magnetic flux density generated when the steel plate 200 is magnetized decreases. When considering a transformer using this steel plate 200, its performance should ideally be characterized by low iron loss and high magnetic flux density. Therefore, from Figures 18 and 19, the inclination angle θ G It is preferable to adopt a tilt angle of 30° to 60°. G It is preferable to control the laser irradiation unit 1 after making a determination based on the captured image so that a θ of 30° to 60° is obtained. Particularly preferable is θ G A range of approximately 40° is suitable.

[0152] In this embodiment, as described above, the inclination angle θ of the groove 201 is determined from the difference in brightness between multiple observation cameras (cameras 21a, 21b) with different observation angles. G It is possible to determine this by appropriately setting the observation angle, the inclination angle θ G It is possible to determine whether the magnetic properties are within a favorable range. As a specific example, the θ that is considered particularly favorable is G This section explains how to determine whether or not a position is in the vicinity of =40°.

[0153] As shown in Figure 14, the inclination angle of the two cameras 21a and 21b from the observation axis and the Z axis is θ C1 θC2 The tilt angle of the illumination light axis from the Z axis is θ L Furthermore, from the viewpoint of magnetic properties, the preferred inclination angle of the side wall of the groove 201 is θ G0 Therefore, these relationships can be expressed by equations 1 and 2 below. Note that, for each angle, the normal to the surface of the steel plate (Z-axis) is 0°, and clockwise is a positive angle, and counterclockwise is a negative angle. θ C1 = -θ L ...(Formula 1) θ C2 =A-θ L ...(Formula 2) 60°≦A≦120° (Formula 3)

[0154] Here, A = 2 × θ G0 θ G0 Since the magnetic properties are good in the range of 30° to 60°, it is preferable to set the range of A using Equation 3. Among these, θ is an example of a particularly favorable magnetic property. G0 For the case where =40°, A=80°, θ L = 50°, θ C1 = -30°, θ C2 Set =30°, groove inclination angle θ G They observed the brightness of multiple grooves that differed from each other.

[0155] For the determination, the brightness ratio Re of the captured image may be used. The brightness ratio Re is defined as follows. For camera 21a, the average observed brightness of the flat steel plate area other than the groove 201 was taken as Em1, and the observed brightness of the groove sidewall was taken as E1, and the brightness ratio Re1 = E1 / Em1 was calculated. Note that Em1 is the specular reflected brightness for camera 21a and is the maximum brightness observed by camera 21a. For camera 21b, a groove 201 with an inclination angle of 40° was prepared, and the average observed brightness of the inclined sidewall of the groove 201 in this case was taken as Em2. In addition, the observed brightness of the inclined sidewall of groove 201 with a different inclination angle was taken as E2, and the brightness ratio Re2 = E2 / Em2 was calculated. Note that in this setting, Em2 is the specular reflected brightness for camera 21b and is the maximum brightness observed by camera 21b. Brightness ratios Re1 and Re2 correspond to relative calibration values ​​with the maximum observed brightness observed by each camera 21a and 21b set to 100%.

[0156] Figure 20(a) shows an example of displaying the imaging brightness of camera 21a. Figure 20(b) shows the distribution of the brightness ratio Re1 in the Y direction, i.e., the direction perpendicular to the extension direction of groove 201, based on Figure 20(a). Here, in the arrangement shown in Figure 14, the points where the brightness ratio Re1 decreases sharply and the points where it increases sharply with respect to the positive Y direction are determined to be the side walls of groove 201. The determination of the amount of change in brightness ratio Re1 may be made, for example, in the range where the brightness ratio Re1 changes from 90% to 10%. Alternatively, the determination may be made using the differential value of the brightness ratio Re1.

[0157] Figure 20(c) shows an example of displaying the luminance ratio Re2 based on the imaging results of camera 21b. Cameras 21a and 21b adjust their imaging positions to make the positions of the groove 201 within the imaging screen coincide. Therefore, as shown in Figure 20(c), it is determined which position of the side wall portion of the groove 201 determined by camera 21a is located within the imaging screen of camera 21b.

[0158] Figure 21 shows the inclination angle θ of the side wall of groove 201. G This graph shows the relationship between the luminance ratio Re2 of the side wall and the luminance ratio of the side wall. Here, A = 80°, θ L = 50°, θ C1 = -50°, θ C2 =30°, θ C1 = -θL θ C2 =A-θ L That is the case. In the configuration of this embodiment, the inclination angle θ of the side wall G In the preferred range of 30° to 60°, the luminance ratio Re2 value is 80% or higher. Therefore, the magnetic properties can be determined by determining whether or not the luminance ratio Re2 falls within this range. Furthermore, the criteria for judgment are not limited to the above range, but also include the value of A and θ. L If the specifications are changed as appropriate, they may be adjusted and modified accordingly.

[0159] (Sixth Embodiment) A sixth embodiment of the present invention will be described below with reference to Figures 22 and 23. Figure 22 is a block diagram showing the schematic configuration of the judgment result mapping device. Figure 23 is a map showing the groove shape defect areas and protrusion remaining areas mapped over the entire length of the steel plate by the judgment result mapping device.

[0160] As shown in Figure 22, in this embodiment, the calculation processing unit 3 includes a first determination unit 32, a second determination unit 56, a steel plate position tracking device 3r, and a determination result mapping device 3s. The steel plate position tracking device 3r acquires the formation positions of all grooves 201 in the steel plate 200 as plate position information. The first determination unit 32 determines whether or not there is a defect in the shape of the groove 201. The second determination unit 56 determines whether or not there is a protrusion that should be removed.

[0161] Then, for all grooves 201 in the steel plate 200, the plate position information is linked to the presence or absence of shape defects and the presence or absence of protrusions that should be removed. The linked information in this way is then mapped and displayed by the judgment result mapping device 3s as shown in Figure 23. This makes it possible to identify groove shape defects and remaining protrusions along the entire length of the coil. Based on this map, it becomes possible to classify the coils by rank or application.

[0162] The present invention allows for various embodiments and modifications without departing from the broad spirit and scope of the invention. Furthermore, the embodiments described above are for illustrative purposes only and do not limit the scope of the invention. In other words, the scope of the invention is indicated not by the embodiments, but by the claims. Various modifications made within the scope of the claims and the equivalent scope of the meaning of the invention are considered to be within the scope of the invention. In addition, in the embodiments described above, the captured image and the training image naturally include not only the specific image form displayed on a display unit such as a screen, but also the data before it is generated as an image on the display unit. Furthermore, a steel plate processing apparatus may be constructed by appropriately combining the configurations of the first to sixth embodiments described above.

[0163] Furthermore, although the above-described embodiment mentions the application of a brush roll 41 as a removal unit for removing protrusions formed on the steel plate 200, the present invention is not limited to this, and various other removal methods can be applied as processing in the removal unit, such as non-roll brush processing or chemical processing such as pickling to remove protrusions formed on the steel plate 200. In this case, the brush control unit 43 operates the removal unit by performing control according to the type of removal unit, and removes the protrusions formed on the steel plate 200 with the removal unit.

[0164] The main points of the steel sheet processing apparatus and control method for the steel sheet processing apparatus according to each embodiment described above are summarized below. (1) As illustrated in Figures 1, 4, etc., one aspect of the present invention is A steel sheet processing apparatus 100 for processing grooves 201 on the surface of a steel sheet 200 that is passed through in the direction of sheet passage, A laser irradiation unit 1 irradiates the surface with a laser beam to form grooves 201 that are parallel or substantially parallel to the width direction of the steel plate 200, An illumination unit 22 irradiates pulsed light into the groove 201 formed by the laser irradiation unit 1, An imaging unit 21 generates an image by imaging the groove 201 irradiated with the pulsed light for an exposure time longer than the irradiation time of the pulsed light, A determination unit 32 that performs a determination based on the captured image, A processing control unit 33 controls the operation of the laser irradiation unit 1, It has, The determination unit 32 determines, based on the captured image, whether the groove 201 satisfies a first criterion relating to at least one of the depth and width of the groove 201. If the determination unit 32 determines that the groove 201 does not meet the first criterion, the processing control unit 33 controls the laser irradiation unit 1 so that the groove 201 formed by the laser irradiation unit 1 meets the first criterion.

[0165] (2) As illustrated in Figure 14, etc., the above (1) may be configured as follows: When viewed in cross-section along the thickness direction of the steel plate 200, The illumination unit 22 has an illumination optical axis that is on one side with respect to the normal of the surface, The imaging unit 21 includes a camera (first camera) 21a having a first incident optical axis that is in a specular reflection position with respect to the illumination optical axis on the other side of the normal, and a camera (second camera) 21b having a second incident optical axis that is different from the specular reflection position.

[0166] (3) As illustrated in Figure 14, etc., the above (2) may be configured as follows: In the aforementioned cross-section, the angle between the normal and the illumination light axis is θ. L (°), the angle between the normal and the first incident optical axis is θ. C1 (°), the angle between the normal and the second incident optical axis is θ. C2 When (°) is used, the following equations 1 to 3 are satisfied. θ C1 = -θ L ...(Formula 1) θ C2 =A-θ L ...(Formula 2) 60°≦A≦120° (Formula 3)

[0167] (4) As illustrated in Figure 1, etc., the above (3) may be configured as follows: Based on the image captured by camera (first camera) 21a and the image captured by camera (second camera) 21b, the determination unit 32 further determines the inclination angle θ of the side wall of the groove 201 in the cross-section. G Determine whether the second criterion is met. If the determination unit 32 determines that the second criterion is not met, the processing control unit 33 controls the laser irradiation unit 1 so that both the first and second criterion are met.

[0168] (5) As illustrated in Figures 1 and 12, the configuration in any one of the above items (1) to (4) may be as follows: The system further includes a brush roll (removal section) 41 for removing protrusions formed in the groove 201. The processing control unit 33 controls the brush roll (removal unit) 41 in addition to controlling the laser irradiation unit 1. The illumination unit 22 and the imaging unit 21 are positioned downstream in the direction of the plate passage from the position of the brush roll (removal unit) 41. The determination unit 32 determines, based on the captured image, A first determination unit 32 that determines whether the groove 201 satisfies the first criterion, The second determination unit 56 determines whether the projection formed in the groove 201 satisfies a third criterion relating to at least one of the height and width of the projection, If the second determination unit 56 determines that the protrusion does not meet the third criterion, the processing control unit 33 controls the brush roll (removal unit) 41 to remove the protrusion.

[0169] (6) As illustrated in Figure 12, etc., the above (5) may be configured as follows: The system further includes another illumination unit 22 and an imaging unit 21 positioned between the laser irradiation unit 1 and the brush roll (removal unit) 41 in the direction of plate passage.

[0170] (7) As illustrated in Figure 22, etc., any one of the above items (1) to (5) may be configured as follows: A steel plate position tracking device (tracking unit) 3r that acquires the position of the groove 201 and the position of the protrusion on the surface of the steel plate 200, A determination result mapping device (mapping unit) 3s creates a map that includes groove information linking the position of groove 201 and the shape of groove 201, and protrusion information linking the position of the protrusion and the shape of the protrusion, To further prepare.

[0171] (8) As illustrated in Figures 1, 11, etc., other aspects of the present invention are: A steel sheet processing device 100 for processing grooves on the surface of a steel sheet 200 that is passed through in the direction of sheet passage, A laser irradiation unit 1 irradiates the surface with a laser beam to form grooves 201 that are parallel or substantially parallel to the width direction of the steel plate 200, An illumination unit 22 irradiates pulsed light into the groove 201 formed by the laser irradiation unit 1, An imaging unit 21 generates an image by imaging the groove 201 irradiated with the pulsed light for an exposure time longer than the irradiation time of the pulsed light, A determination unit 32 that performs a determination based on the captured image, A brush roll (removal unit) 41 for removing protrusions formed in the groove 201, A brush control unit (processing control unit) 43 controls the operation of the brush roll (removal unit) 41, It has, The determination unit 32 determines, based on the captured image, whether the protrusion formed in the groove 201 satisfies a third criterion relating to at least one of the height and width of the protrusion. If the determination unit 32 determines, based on the captured image, that the protrusion does not meet the third criterion, the brush control unit (processing control unit) 43 controls the brush roll (removal unit) 41 to remove the protrusion.

[0172] (9) As illustrated in Figure 13, etc., any one of the above items (1) to (8) may be configured as follows: The determination unit 32 makes a determination using the machine learning model 63 generated by machine learning.

[0173] (10) As illustrated in Figures 1, 4, etc., yet another aspect of the present invention is A control method for a steel sheet processing apparatus 100 that processes grooves 201 on the surface of a steel sheet 200 that is passed through in the direction of sheet passage, A laser irradiation step S1 involves irradiating the surface with a laser beam from the laser irradiation unit 1 to form grooves that are parallel or substantially parallel to the width direction of the steel plate 200, Lighting step S2 involves irradiating the groove 201 with pulsed light from the lighting unit 22, The imaging step S3 generates an image by imaging the groove 201 irradiated with the pulsed light using the imaging unit 21 for an exposure time longer than the irradiation time of the pulsed light, A determination step S4 in which the determination unit 32 makes a determination based on the captured image, A processing control step S5 in which the operation of the laser irradiation unit 1 is controlled by the processing control unit 33, It has, In determination step S4, based on the captured image, it is determined whether the groove satisfies a first criterion relating to at least one of the depth and width of the groove 201. If it is determined in the determination step S4 that the groove 201 does not meet the first criterion, the processing control step S1 controls the laser irradiation unit 1 so that the groove 201 formed by the laser irradiation unit 1 meets the first criterion.

[0174] (11) As illustrated in Figures 1, 14, etc., the above (10) may be done as follows: When viewed in cross-section along the thickness direction of the steel plate 200, In illumination step S2, the pulsed light is irradiated along the illumination optical axis which is on one side with respect to the normal to the surface of the steel plate 200, In imaging step S3, imaging is performed along a first incident optical axis that is at the specular reflection position with respect to the illumination optical axis on the other side of the normal, and along a second incident optical axis that is different from the specular reflection position.

[0175] (12) As illustrated in Figure 14, etc., the above (11) may be done as follows: In the aforementioned cross-section, the angle between the normal and the illumination light axis is θ. L (°), the angle between the normal and the first incident optical axis is θ. C1 (°), the angle between the normal and the second incident optical axis is θ. C2 When we consider (°), In the illumination step S2 and the imaging step S3, the illumination optical axis, the first incident optical axis, and the second incident optical axis are set to satisfy the following equations 1 to 3. θ C1 = -θ L ...(Formula 1) θ C2 =A-θ L ...(Formula 2) 60°≦A≦120° (Formula 3)

[0176] (13) As illustrated in Figure 1, etc., the above (12) may be done as follows: In the determination step S4, based on the captured image taken in the first incident optical axis and the captured image taken in the second incident optical axis, the inclination angle θ of the side wall of the groove 201 is determined. G Determine whether the second criterion is met. If the determination step S4 determines that the second criterion is not met, the processing control step S5 controls the laser irradiation unit 1 so that both the first and second criterion are met.

[0177] (14) Any one of the above items (10) to (13) may be done as follows: A time-lapse imaging step involves acquiring multiple images of the groove 201 passing through the same position in the width direction of the steel plate 200 over time, A time-series change acquisition step, based on each of the captured images obtained in the time-series imaging step, acquires the time-series change in the shape of each groove 201 passing through the same position, Based on whether the time-dependent changes obtained in the time-dependent change acquisition step meet the fourth criterion, a step is made to determine whether or not adjustment of the laser irradiation unit 1 is necessary. It further possesses.

[0178] (15) As illustrated in Figures 1 and 12, etc., any one of the above items (10) to (14) may be done as follows: The processing control step S5 includes a step S5-3 in which a brush roll (removal unit) 41 located downstream of the laser irradiation unit 1 in the direction of plate passage is used to remove protrusions formed in the groove 201. In the determination step S4, in addition to determining the groove 201, it is also determined, based on the captured image, whether or not a third criterion, which is a criterion relating to at least one of the height and width of the protrusion, is met. If the determination step S4 determines that the protrusion does not meet the third criterion, the processing control step S5 removes the protrusion.

[0179] (16) As illustrated in Figure 12, etc., the above (15) may be done as follows: The illumination step S2, the imaging step S3, and the determination step S4 are performed as follows: The position between the laser irradiation unit 1 and the brush roll (removal unit) 41 in the direction of plate passage, A position downstream of the brush roll (removal section) 41 in the aforementioned plate passage direction, Each of these will be handled individually.

[0180] (17) As illustrated in Figure 22, etc., any one of the above items (10) to (15) may be done as follows: A tracking step to obtain the position of the groove 201 and the position of the protrusion on the surface of the steel plate 200, A mapping step to create a map that includes groove information linking the position of groove 201 and the shape of groove 201, and protrusion information linking the position of the protrusion and the shape of the protrusion, It further possesses.

[0181] (18) As illustrated in Figures 1, 11, etc., yet another aspect of the present invention is A control method for a steel sheet processing apparatus 100 that processes grooves 201 on the surface of a steel sheet 200 that is passed through in the direction of sheet passage, A laser irradiation step S1 involves irradiating the steel plate 200 with a laser beam from the laser irradiation unit 1 to form grooves parallel or substantially parallel to the width direction of the steel plate 200, Lighting step S2 involves irradiating the groove 201 with pulsed light from the lighting unit 22, The imaging step S3 generates an image by imaging the groove 201 irradiated with the pulsed light using the imaging unit 21 for an exposure time longer than the irradiation time of the pulsed light, A determination step S4 in which the determination unit 32 makes a determination based on the captured image, The removal step S5-3 involves removing the protrusions formed in the groove 201 using a brush roll (removal unit) 41, It has, In the determination step S4, based on the captured image, it is determined whether or not the third criterion, which is a criterion relating to at least one of the height and width of the protrusion, If the determination step S4 determines that the protrusion does not meet the third criterion, the processing control step S5 controls the brush roll (removal unit) 41 to remove the protrusion.

[0182] (19) As illustrated in Figures 1, 13, etc., any one of the above items (10) to (18) may be done as follows: The determination in the determination step S4 is performed using the machine learning model 63 generated by machine learning. [Industrial applicability]

[0183] According to the above embodiments of the present invention, even when the steel sheet is fed at a high speed, it is possible to generate an image that clearly captures the grooves formed on the surface of the steel sheet. Based on this image, it becomes possible to determine the state of the grooves, and feedback control related to groove processing can be performed based on the determination, so that steel sheets with desired magnetic properties can be manufactured stably. Therefore, it has great industrial applicability. [Explanation of Symbols]

[0184] 1. Laser irradiation area 3, 3b, 3c Calculation Processing Unit 21, 54 Imaging Unit 22, 55 Lighting Unit 31 Synchronization Unit 32, 56 Judgment Unit 33 Processing Control Unit 41 Brush Roll (Removal Unit) 43 Brush Control Unit 63 Machine Learning Model 100 Steel Plate Processing Device 200 Steel Plate 201 Groove

Claims

1. A steel sheet processing apparatus for processing grooves on the surface of a steel sheet that is passed through in the direction of sheet passage, A laser irradiation unit that irradiates the surface with a laser beam to form grooves parallel or substantially parallel to the width direction of the steel plate, An illumination unit that irradiates pulsed light into the groove formed by the laser irradiation unit, An imaging unit generates an image by imaging the groove irradiated with the pulsed light for an exposure time longer than the irradiation time of the pulsed light, A determination unit that performs a determination based on the captured image, A processing control unit that controls the operation of the laser irradiation unit, It has, The determination unit determines, based on the captured image, whether the groove satisfies a first criterion relating to at least one of the depth and width of the groove. If the determination unit determines that the groove does not meet the first criterion, the processing control unit controls the laser irradiation unit so that the groove formed by the laser irradiation unit meets the first criterion. A steel plate processing apparatus characterized by the following features.

2. When viewed in cross-section along the thickness direction of the steel plate, The illumination unit has an illumination optical axis that is on one side with respect to the normal of the surface, The imaging unit includes a first camera having a first incident optical axis that is in a specular reflection position with respect to the illumination optical axis on the other side of the normal, and a second camera having a second incident optical axis that is different from the specular reflection position. The steel plate processing apparatus according to feature 1.

3. In the aforementioned cross-section, the angle between the normal and the illumination light axis is θ. Ｌ (°), the angle between the normal and the first incident optical axis is θ Ｃ１ (°), the angle between the normal and the second incident optical axis is θ Ｃ２ When (°), the following equations 1 to 3 are satisfied. The steel plate processing apparatus according to feature 2. i Ｃ１ =-θ Ｌ ・・・ (formula 1) i Ｃ２ =A-θ Ｌ ・・・ (formula 2) 60°≦A≦120°...(Formula 3)

4. Based on the image captured by the first camera and the image captured by the second camera, the determination unit further determines whether the inclination angle of the side wall of the groove in the cross-section satisfies a second criterion. If the determination unit determines that the second criterion is not met, the processing control unit controls the laser irradiation unit so that both the first and second criterion are met. The steel plate processing apparatus according to feature 3.

5. The system further includes a removal unit for removing protrusions formed in the groove, The processing control unit controls the removal unit in addition to controlling the laser irradiation unit. The illumination unit and the imaging unit are positioned downstream in the direction of the plate passage from the position of the removal unit. The determination unit, based on the captured image, A first determination unit that determines whether the groove satisfies the first criterion, The system includes a second determination unit that determines whether the projection formed in the groove satisfies a third criterion relating to at least one of the height and width of the projection, If the second determination unit determines that the protrusion does not meet the third criterion, the processing control unit controls the removal unit to remove the protrusion. The steel plate processing apparatus according to feature 1.

6. The system further comprises another illumination unit and an imaging unit positioned between the laser irradiation unit and the removal unit in the direction of the plate passage. The steel plate processing apparatus according to feature 5.

7. A tracking unit that acquires the position of the groove and the position of the protrusion on the surface of the steel plate, A mapping unit creates a map that includes groove information linking the position of the groove and the shape of the groove, and protrusion information linking the position of the protrusion and the shape of the protrusion. The steel plate processing apparatus according to claim 5, further comprising the features described above.

8. A steel sheet processing apparatus for processing grooves on the surface of a steel sheet that is passed through in the direction of sheet passage, A laser irradiation unit that irradiates the surface with a laser beam to form grooves parallel or substantially parallel to the width direction of the steel plate, An illumination unit that irradiates pulsed light into the groove formed by the laser irradiation unit, An imaging unit generates an image by imaging the groove irradiated with the pulsed light for an exposure time longer than the irradiation time of the pulsed light, A determination unit that performs a determination based on the captured image, A removal unit for removing protrusions formed in the groove, A processing control unit that controls the operation of the removal unit, It has, The determination unit determines, based on the captured image, whether the protrusion formed in the groove satisfies a third criterion relating to at least one of the height and width of the protrusion. If the determination unit determines, based on the captured image, that the protrusion does not meet the third criterion, the processing control unit controls the removal unit to remove the protrusion. A steel plate processing apparatus characterized by the following features.

9. The steel plate processing apparatus according to any one of claims 1 to 8, characterized in that the determination unit performs determination using a machine learning model generated by machine learning.

10. A control method for a steel sheet processing apparatus that processes grooves on the surface of a steel sheet that is passed through in the direction of sheet passage, A laser irradiation step involves irradiating the surface with a laser beam from a laser irradiation unit to form grooves that are parallel or substantially parallel to the width direction of the steel plate, A lighting step in which pulsed light from the lighting unit is irradiated onto the groove, An imaging step to generate an image by imaging the groove irradiated with the pulsed light using an imaging unit for an exposure time longer than the irradiation time of the pulsed light, A determination step in which a determination unit makes a determination based on the captured image, A processing control step in which the operation of the laser irradiation unit is controlled by a processing control unit, It has, In the determination step, based on the captured image, it is determined whether the groove satisfies a first criterion relating to at least one of the depth and width of the groove. If the determination step determines that the groove does not meet the first criterion, the processing control step controls the laser irradiation unit so that the groove formed by the laser irradiation unit meets the first criterion. A control method for a steel sheet processing apparatus, characterized by the following features.

11. When viewed in cross-section along the thickness direction of the steel plate, In the illumination step, the pulsed light is irradiated along an illumination optical axis that is on one side with respect to the normal to the surface of the steel plate. In the imaging step, imaging is performed along a first incident optical axis that is at the specular reflection position with respect to the illumination optical axis on the other side of the normal, and along a second incident optical axis that is different from the specular reflection position. A control method for a steel sheet processing apparatus according to feature 10.

12. When looking at the cross section, the angle formed by the normal line and the illumination optical axis is θ Ｌ (°), the angle formed by the normal line and the first incident optical axis is θ Ｃ１ (°), and the angle formed by the normal line and the second incident optical axis is θ Ｃ２ (°), then In the illumination step and the imaging step, the illumination optical axis, the first incident optical axis, and the second incident optical axis are set to satisfy the following equations 1 to 3. A control method for a steel sheet processing apparatus according to feature 11. i Ｃ１ =-θ Ｌ ・・・ (formula 1) i Ｃ２ =A-θ Ｌ ・・・ (formula 2) 60°≦A≦120°...(Formula 3)

13. In the determination step, based on the image captured in the first incident optical axis and the image captured in the second incident optical axis, it is further determined whether the inclination angle of the side wall of the groove satisfies a second criterion. If the determination step determines that the second criterion is not met, the processing control step controls the laser irradiation unit so that both the first and second criterion are met. A control method for a steel sheet processing apparatus according to feature 12.

14. The processing control step includes a step of removing protrusions formed in the groove using a removal unit located downstream of the laser irradiation unit in the direction of plate passage, In the determination step, in addition to determining the groove, it is also determined, based on the captured image, whether or not a third criterion, which is a criterion relating to at least one of the height and width of the protrusion, is met. If the determination step determines that the protrusion does not meet the third criterion, the processing control step removes the protrusion. A control method for a steel sheet processing apparatus according to feature 10.

15. The illumination step, the imaging step, and the determination step are performed as follows: The position between the laser irradiation section and the removal section in the plate passing direction, A position downstream of the removal section in the direction of the passing plate, Each of these will be done individually. A control method for a steel sheet processing apparatus according to feature 14.

16. A tracking step to obtain the position of the groove and the position of the protrusion on the surface of the steel plate, A mapping step to create a map that includes groove information linking the position of the groove and the shape of the groove, and protrusion information linking the position of the protrusion and the shape of the protrusion, A control method for a steel plate processing apparatus according to claim 14, further comprising the above.

17. A control method for a steel sheet processing apparatus that processes grooves on the surface of a steel sheet that is passed through in the direction of sheet passage, A laser irradiation step involves irradiating the steel plate with a laser beam from a laser irradiation unit to form grooves that are parallel or substantially parallel to the width direction of the steel plate, A lighting step in which pulsed light from the lighting unit is irradiated onto the groove, An imaging step to generate an image by imaging the groove irradiated with the pulsed light using an imaging unit for an exposure time longer than the irradiation time of the pulsed light, A determination step in which a determination unit makes a determination based on the captured image, A removal step in which a protrusion formed in the groove is removed by a removal unit, It has, In the determination step, based on the captured image, it is determined whether or not a third criterion, which is a criterion relating to at least one of the height and width of the protrusion, is met. If the determination step determines that the protrusion does not meet the third criterion, the removal step controls the removal unit to remove the protrusion. A control method for a steel sheet processing apparatus, characterized by the following features.

18. A control method for a steel plate processing apparatus according to any one of claims 10 to 17, characterized in that the determination in the determination step is performed using a machine learning model generated by machine learning.

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