Method for determining processing state of grain-oriented electrical steel sheet, processing state determination device, method for adjusting manufacturing facility, manufacturing method, quality management method, and manufacturing facility

Abstract

This method for determining the working state of a grain-oriented electrical steel sheet comprises: a magnetization step for applying a direct-current or alternating-current magnetic field to a region of the grain-oriented electrical steel sheet subjected to magnetic domain refinement processing; a detection step for detecting, for each of a plurality of regions in the width direction of the grain-oriented magnetic steel sheet, a leakage magnetic flux generated in the grain-oriented magnetic steel sheet as a result of the application of the magnetic field; a calculation step for calculating the frequency distribution of each region on the basis of an output signal that opposes the position in the longitudinal direction of the grain-oriented magnetic steel sheet in the leakage flux of each region detected in the detection step; and a determination step for determining the state of the magnetic domain refinement for each region on the basis of a determination index calculated from the intensity level within a prescribed range of the frequency distribution of each region.

Description

Technical Field

[0001] The present invention relates to a method for determining a processing state of a grain-oriented electromagnetic steel sheet, a processing state determining device, an adjustment method for manufacturing equipment, a manufacturing method, a quality management method, and manufacturing equipment. Background Art

[0002] The electromagnetic properties of electromagnetic steel sheets are among the most important characteristics that influence product performance. Evaluation criteria include iron loss, maximum magnetic permeability, and magnetostriction. Iron loss refers to the energy loss caused by the dissipation of magnetic energy as heat due to hysteresis and eddy currents when an AC magnetic field is applied to the electromagnetic steel sheet. Therefore, electromagnetic steel sheets with low iron loss have higher energy conversion efficiency, thus offering an advantage over sheets with high iron loss. Technologies have been developed to reduce iron loss in grain-oriented electromagnetic steel sheets. One such technology involves a magnetic domain refinement process, which physically introduces localized nonuniformities periodically in the surface layer in the rolling direction, thereby reducing the width of the magnetic domains and reducing iron loss.

[0003] The magnetic domain refinement process only needs to introduce unevenness into the surface layer, and is not necessarily limited to methods that change the shape of holes, grooves, etc. in the surface layer. It can be any method that introduces unevenness into the surface layer without changing the shape. This can be achieved, for example, by applying heat, pressure, etc. More specifically, unevenness can be introduced into the surface layer by irradiating lasers, electron beams, plasma jets, etc. Magnetic domains magnetized in the rolling direction parallel to the easy magnetization axis are formed on the directional electromagnetic steel sheet. However, in the uneven portion of the surface layer applied by the magnetic domain refinement process, even if there is no damage or change in shape, magnetic domains magnetized in a direction different from the rolling direction will be locally formed, and this discontinuity of magnetization will produce magnetic domain refinement.

[0004] As a method for evaluating an electron beam-based magnetic domain refinement process, the method described in Patent Document 1 is known. Specifically, the method described in Patent Document 1 evaluates the focus position offset of the electron beam using the luminous brightness distribution of the electron beam. In addition, as methods for evaluating the processing status of a magnetic domain refinement process, the methods described in Patent Document 2 and Patent Document 3 are known. The method described in Patent Document 2 uses eddy current to evaluate the magnetic domain refinement processing status, and the method described in Patent Document 3 uses leakage flux to evaluate the magnetic domain refinement processing status. In both methods, a fast Fourier transform operation is performed to evaluate the magnetic domain refinement processing status based on the intensity level of a wavelength equivalent to the magnetic domain refinement processing interval.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 6398961

[0008] Patent Document 2: Japanese Patent No. 6562055

[0009] Patent Document 3: Japanese Patent No. 6607242 Summary of the Invention

[0010] Problems to be solved by the invention

[0011] In the method described in Patent Document 1, it is necessary to use a camera to capture the irradiation position of the electron beam. However, dirt or vapor deposition caused by processing may sometimes adhere to the lens of the camera, the window on the shooting path, etc. Therefore, in order to stably evaluate the focus position offset of the electron beam, it is necessary to frequently maintain the camera, etc., which requires a lot of labor. On the other hand, in the methods described in Patent Documents 2 and 3, due to signals from other equipment in the production line, deviations in manufacturing conditions, etc., it is sometimes not possible to obtain a correlation between the intensity level of the wavelength corresponding to the magnetic domain refinement processing interval and the quality of the magnetic domain refinement processing state. Therefore, it is sometimes impossible to determine the magnetic domain refinement processing state with high precision. Moreover, according to the methods described in Patent Documents 2 and 3, the quality of the magnetic domain refinement processing state of the entire steel plate can be determined, but the quality of the magnetic domain refinement processing state within a specific range of the steel plate, such as only a certain part in the width direction of the steel plate, cannot be determined.

[0012] The present invention was developed to address the aforementioned issues, and its purpose is to provide a method and apparatus for determining the processing state of a grain-oriented electromagnetic steel sheet that can accurately determine the magnetic domain refinement processing state within a specific range of the steel sheet without requiring extensive labor. Furthermore, another object of the present invention is to provide a method for adjusting and manufacturing equipment for grain-oriented electromagnetic steel sheet that can manufacture grain-oriented electromagnetic steel sheet with a high yield. Furthermore, another object of the present invention is to provide a method for managing the quality of grain-oriented electromagnetic steel sheet that can stably provide high-quality grain-oriented electromagnetic steel sheet. Furthermore, another object of the present invention is to provide equipment for manufacturing grain-oriented electromagnetic steel sheet that can manufacture grain-oriented electromagnetic steel sheet with a high yield.

[0013] Means for solving problems

[0014] [1] The method for determining the processing state of a grain-oriented electromagnetic steel sheet according to the present invention comprises: a magnetizing step of applying a DC or AC magnetic field to a region of the grain-oriented electromagnetic steel sheet on which magnetic domain refinement processing has been performed; a detecting step of detecting, for each of a plurality of regions in the width direction of the grain-oriented electromagnetic steel sheet, leakage magnetic flux generated in the grain-oriented electromagnetic steel sheet accompanying the application of the magnetic field; a calculating step of calculating a frequency distribution of each region based on an output signal of the leakage magnetic flux of each region detected in the detecting step relative to a position in the longitudinal direction of the grain-oriented electromagnetic steel sheet; and a determining step of determining the state of the magnetic domain refinement processing for each region based on a determination index calculated based on an intensity level within a predetermined range of the frequency distribution of each region.

[0015] [2] In the method for determining the processing state of an electromagnetic steel sheet according to the present invention, in the invention of [1] above, the predetermined range is set based on the interval of the magnetic domain refining processing.

[0016] [3] The method for determining the processing state of an electromagnetic steel sheet of the present invention in the invention of [1] or [2] above includes the step of determining the state of the magnetic domain refining processing based on the two-dimensional distribution of the strength level in the in-plane direction of the grain-oriented electromagnetic steel sheet.

[0017] [4] The processing state determination device of the electromagnetic steel sheet of the present invention comprises: a magnetizer for applying a DC or AC magnetic field to a region of the directional electromagnetic steel sheet where magnetic domain refinement processing has been performed; a plurality of magnetic sensors for detecting leakage magnetic flux generated in the directional electromagnetic steel sheet accompanying the application of the magnetic field for each of a plurality of regions in the width direction of the directional electromagnetic steel sheet; and a signal processing unit for calculating a frequency distribution of each region based on output signals of the leakage magnetic flux of each region detected by the plurality of magnetic sensors relative to the position in the longitudinal direction of the directional electromagnetic steel sheet, and determining the state of the magnetic domain refinement processing for each of the regions based on a determination index calculated based on an intensity level within a specified range of the frequency distribution of each region.

[0018] [5] In the electromagnetic steel sheet processing state determination device of the present invention, in the invention of [4] above, the predetermined range is set based on the interval of the magnetic domain refining processing.

[0019] [6] In the electromagnetic steel sheet processing state determination device of the present invention, in the invention of [4] or [5] above, the signal processing unit determines the state of the magnetic domain refining processing based on the two-dimensional distribution of the intensity level in the in-plane direction of the grain-oriented electromagnetic steel sheet.

[0020] [7] The method for adjusting equipment for manufacturing grain-oriented electromagnetic steel sheets of the present invention includes the step of adjusting the state of the equipment for manufacturing grain-oriented electromagnetic steel sheets based on the state of magnetic domain refinement processing of each of the regions determined using the method for determining the processing state of grain-oriented electromagnetic steel sheets according to any one of claims [1] to [3].

[0021] [8] The method for manufacturing a grain-oriented electromagnetic steel sheet of the present invention includes the step of controlling the conditions of the magnetic domain refinement processing based on the state of the magnetic domain refinement processing of each of the regions determined using the method for determining the processing state of a grain-oriented electromagnetic steel sheet according to any one of [1] to [3] above.

[0022] [9] The quality management method of the grain-oriented electromagnetic steel sheet of the present invention includes: performing quality management of the grain-oriented electromagnetic steel sheet based on the state of magnetic domain refinement processing of each of the above-mentioned regions determined using the processing state determination method of the grain-oriented electromagnetic steel sheet according to any one of [1] to [3].

[0023]

[10] The manufacturing equipment of the grain-oriented electrical steel sheet of the present invention comprises the grain-oriented electrical steel sheet processing state determination device according to any one of [4] to [6].

[0024] Effects of the Invention

[0025] The processing state determination method and processing state determination device for grain-oriented electrical steel sheets according to the present invention can accurately determine the magnetic domain refinement state of a specific portion of a steel sheet without requiring extensive labor. Furthermore, the adjustment method and manufacturing method for grain-oriented electrical steel sheet manufacturing equipment according to the present invention can manufacture grain-oriented electrical steel sheets with a high yield. Furthermore, the quality management method for grain-oriented electrical steel sheets according to the present invention can stably provide high-quality grain-oriented electrical steel sheets. Furthermore, the manufacturing equipment for grain-oriented electrical steel sheets according to the present invention can manufacture grain-oriented electrical steel sheets with a high yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram showing the structure of the processing state determination device of the grain-oriented electrical steel sheet according to the present invention.

[0027] Figure 2 It is a diagram showing a two-dimensional map of leakage magnetic flux detected from a grain-oriented electromagnetic steel sheet with a good magnetic domain refining state and a grain-oriented electromagnetic steel sheet with a poor magnetic domain refining state.

[0028] Figure 3 This is a schematic diagram showing the configuration of a grain-oriented electrical steel sheet working state determination device according to one embodiment of the present invention.

[0029] Figure 4This diagram shows output signals of magnetic sensors in a certain lane on an actual production line converted into measured positions in the longitudinal direction of grain-oriented electromagnetic steel sheets.

[0030] Figure 5 This figure shows the results of FFT calculation processing in the easy magnetization axis direction on the leakage flux measurement results of grain-oriented electromagnetic steel sheets with sufficient magnetic domain refinement and grain-oriented electromagnetic steel sheets with insufficient magnetic domain refinement.

[0031] Figure 6 Yes Figure 5 A diagram showing the FFT intensity level of the calculation range of the judgment index in the example shown.

[0032] Figure 7 This graph plots the correlation coefficient between the judgment index and the difference between the planned and actual iron loss.

[0033] Figure 8 It is a diagram showing an example of arrangement of a processing machine and a magnetic sensor.

[0034] Figure 9 This is a diagram showing an example of determining the state of magnetic domain refining processing using an FFT determination index.

[0035] Figure 10 This is a diagram showing an example of determining the state of magnetic domain refining processing using an FFT determination index.

[0036] Figure 11 This is a schematic diagram showing an example of a two-dimensional mapping of FFT intensity levels.

[0037] Figure 12 This is a flowchart showing the flow of a method for adjusting equipment for producing a grain-oriented electrical steel sheet according to one embodiment of the present invention.

[0038] Figure 13 This is a flowchart showing the flow of a process for creating two-dimensional data of FFT intensity levels. DETAILED DESCRIPTION

[0039] The processing state determination method and processing state determination device of a grain-oriented electrical steel sheet according to the present invention utilize a magnetic flux leakage method to non-destructively and contactlessly measure the leakage magnetic flux of the grain-oriented electrical steel sheet, thereby determining the magnetic domain refinement state of the grain-oriented electrical steel sheet. During the manufacturing process of grain-oriented electrical steel sheet, the magnetic domain refinement process, in principle, involves locally changing the magnetic properties of the grain-oriented electrical steel sheet. Therefore, if the region where the magnetic domain refinement process has been performed (hereinafter referred to as the magnetic domain refinement portion) is considered a localized magnetic discontinuity, magnetic flux (leakage magnetic flux) leaks from the magnetic domain refinement portion. In other words, by measuring the leakage magnetic flux using the magnetic flux leakage method, the magnetic domain refinement state of the grain-oriented electrical steel sheet can be determined.

[0040] Figure 1 Schematic diagram showing the structure of the processing state determination device of the grain-oriented electromagnetic steel sheet of the present invention. Figure 1 As shown, the processing state determination device 1 of the directional electromagnetic steel sheet of the present invention includes a leakage flux detection unit 2 and a signal processing unit 3 as main components. The leakage flux detection unit 2 includes a magnetizer 2a such as an electromagnet that magnetizes the directional electromagnetic steel sheet S in the direction of the easy magnetization axis, and a magnetic sensor 2b. The leakage flux detection unit 2 is arranged on the directional electromagnetic steel sheet S in a non-contact manner, applies external magnetization to the directional electromagnetic steel sheet S passing under the leakage flux detection unit 2, and detects the leakage flux of the directional electromagnetic steel sheet S. Then, the signal processing unit 3 determines the magnetic domain refinement processing state of the directional electromagnetic steel sheet S based on the leakage flux detected by the leakage flux detection unit 2. Figure 1 In the figure, reference symbol SP represents a magnetic domain refining processing portion.

[0041] Figure 2 (a) and (b) are two-dimensional maps of leakage flux detected from a grain-oriented electromagnetic steel sheet with a good magnetic domain refinement state and a grain-oriented electromagnetic steel sheet with a poor magnetic domain refinement state, respectively. Figure 2 As shown in (a), in a grain-oriented electromagnetic steel sheet with a good magnetic domain refinement state, a ribbed magnetic domain refinement portion can be confirmed. Figure 2 As shown in (b), in grain-oriented electrical steel sheets with poor domain refinement, the streak-like domain refinement areas cannot be clearly identified. The iron loss value of grain-oriented electrical steel sheets with good domain refinement is lower than that of grain-oriented electrical steel sheets with poor domain refinement. Therefore, the iron loss value of the grain-oriented electrical steel sheet can be estimated based on the detection status of the streak-like domain refinement areas.

[0042] Typically, magnetic domain refinement is performed in a direction perpendicular to the easy magnetization axis. When assessing the domain refinement status of a grain-oriented electromagnetic steel sheet, a magnetic field smaller than the one required to achieve the width of the magnetic domains parallel to the easy magnetization axis corresponds to the width of the domains in the domain-refined portion. In practice, the magnitude of the magnetic field to be applied is predetermined based on the composition and thickness of the grain-oriented electromagnetic steel sheet through experiments and simulations. When assessing the domain refinement status, a magnetic field appropriate to the composition and thickness of the grain-oriented electromagnetic steel sheet is applied.

[0043] If the result of this determination indicates that the magnetic domain refinement state of the grain-oriented electrical steel sheet is not in the desired state, feedback is provided to the processing machine, allowing the state of the magnetic domain refinement to be corrected in advance. This early correction prevents the production of grain-oriented electrical steel sheet that deviates from specifications and improves the manufacturing yield of the grain-oriented electrical steel sheet. Specifically, when using a laser or electron beam to form the magnetic domain refinement portion, the magnetic domain refinement state of the grain-oriented electrical steel sheet is adjusted to the desired state by adjusting the laser or electron beam output, focus, scanning speed, and the repetition interval (line spacing) of the strain in the longitudinal direction.

[0044] Hereinafter, the structure and operation of the grain-oriented electrical steel sheet working state determination device according to one embodiment of the present invention will be described.

[0045] Figure 3 (a) and (b) are schematic diagrams showing the structure of a device for determining the processing state of a grain-oriented electromagnetic steel sheet according to an embodiment of the present invention. Figure 3 As shown in (a) and (b) of FIG. 1 , a device 10 for determining the machining state of a grain-oriented electromagnetic steel sheet according to an embodiment of the present invention includes a leakage flux detection unit 12, a signal processing unit 13, and an excitation power supply 14 as main components. In this embodiment, the signal processing unit 13 and the excitation power supply 14 are configured separately, but the signal processing unit 13 and the excitation power supply 14 may be configured as one. In addition, Figure 3 In (a) and (b), the longitudinal direction of the grain-oriented electromagnetic steel sheet S is Figure 3 The rolling direction of (b) is the same. On the other hand, Figure 3 In (a) and (b), the width direction of the grain-oriented electromagnetic steel sheet S is Figure 3 The rolling direction in (b) is orthogonal to the direction within the drawing.

[0046] The leakage magnetic flux detection unit 12 includes a magnetizer 12 a and a plurality of magnetic sensors 12 b , and is arranged to face the upper surface of the grain-oriented electromagnetic steel sheet S.

[0047] The magnetizer 12a applies external magnetization to the grain-oriented electromagnetic steel sheet S using excitation power (excitation frequency in the case of AC) supplied from the excitation power supply 14. In this embodiment, the external magnetization, which is a magnitude such that the magnetic domain walls of the magnetic domains in areas not subjected to domain refinement move but the magnetization direction of the magnetic domains in areas subjected to domain refinement is not parallel to the easy magnetization axis, is set to a value within the range of 0 to 100 AT (100 AT: the magnitude of the external magnetization obtained by passing a current of 0.1 A through a 1000-turn coil). At this point, the magnetic flux density of the grain-oriented electromagnetic steel sheet S is 0 to 1.7 mT. The magnetizer 12a can be an electromagnet or a permanent magnet. Considering factors such as the thickness of the grain-oriented electromagnetic steel sheet S and fine adjustment of liftoff, electromagnets are generally easier to adjust. However, even when using permanent magnets, the relative position of the magnetic sensor 12b and the permanent magnet can be adjusted separately.

[0048] Multiple magnetic sensors 12b are arranged across the width of the grain-oriented electromagnetic steel sheet S. Each of the magnetic sensors 12b detects leakage magnetic flux from the grain-oriented electromagnetic steel sheet S, generated by the application of external magnetization, for each of multiple regions (channels) across the width of the grain-oriented electromagnetic steel sheet S. When the external magnetization applied to the grain-oriented electromagnetic steel sheet S is AC, the leakage magnetic flux from the grain-oriented electromagnetic steel sheet S is detected by detecting the excitation frequency. The phase of the detection signal is preferably adjusted during this process. In this embodiment, the magnetic sensors 12b are TMR (tunnel effect) sensors that detect leakage magnetic flux components parallel to the surface of the grain-oriented electromagnetic steel sheet S. Highly sensitive magnetic sensors are preferably used as the magnetic sensors 12b. Examples of suitable sensors include SQUIDs, MI (magneto-impedance), Hall elements, GMR (magneto-resistance), and E-type sensors, which consist of a coil wound around an E-shaped ferromagnetic core.

[0049] The signal processing unit 13 includes an amplifier 13a, multiple bandpass filters (BPFs) 13b, and an information processing unit 13c. The amplifier 13a amplifies the output signals of the multiple magnetic sensors 12b and outputs them to the corresponding BPFs 13b. The multiple BPFs 13b extract output signals within a predetermined frequency band from the output signals of the amplifier 13a and output the extracted output signals to the information processing unit 13c. The information processing unit 13c uses the output signals of the multiple BPFs 13b to determine the processing status of the magnetic domain refining process of the grain-oriented electromagnetic steel sheet S for each of the multiple regions (channels).

[0050] When utilizing the skin effect to generate magnetic flux distribution across the thickness of a grain-oriented electromagnetic steel sheet, the AC leakage flux method using AC current can also be applied. However, this requires a separate AC processing circuit. To evaluate only the amplitude of the output signal, the AC processing circuit only requires an absolute value circuit and a low-pass filter. To evaluate both the amplitude and phase of the output signal, detection at the excitation frequency is necessary, thus requiring a detection circuit.

[0051] When measuring with the magnetic sensor 12b, the grain-oriented electromagnetic steel sheet S is relatively moved by a predetermined length in the direction of the easy magnetization axis. In this case, the grain-oriented electromagnetic steel sheet S can be moved by a conveyor or the like by a predetermined length, or the magnetizer 12a and the magnetic sensor 12b are moved by a predetermined length on the grain-oriented electromagnetic steel sheet S by a moving device or the like, or a combination of the movement of the grain-oriented electromagnetic steel sheet S and the magnetic sensor 12b. In the present invention, the easy magnetization axis of the grain-oriented electromagnetic steel sheet S is the longitudinal direction of the grain-oriented electromagnetic steel sheet S and the rolling direction. In the case of this embodiment, the magnetic sensor 12b and the magnetizer 12a are fixed, and the grain-oriented electromagnetic steel sheet S is moved in the longitudinal direction ( Figure 3 (b) A predetermined length is conveyed in the rolling direction.

[0052] Figure 4 This is a diagram showing the output signal of the magnetic sensor 12b of a certain lane on an actual production line converted into the measured position (unit: mm) in the longitudinal direction of the grain-oriented electromagnetic steel sheet S. Figure 4 In the example shown, the detection pitch of the magnetic sensor 12b is 0.1268mm / point, and the 8.0mm interval magnetic domain refinement processing part is detected as a change in the output signal. In this embodiment, frequency analysis is used as an example of a judgment indicator for such an output signal. In this case, it is preferable to adjust the specified length in the longitudinal direction so that the number of signals can be appropriately analyzed by frequency. Figure 4 In the case of , the relative movement distance of the magnetic sensor 12b in the longitudinal direction of the grain-oriented electromagnetic steel sheet S is 200 mm under the above-mentioned detection pitch condition.

[0053] Figure 5 Figures (a) and (b) show the results of FFT processing of leakage flux measurements in the direction of the easy magnetization axis for grain-oriented electromagnetic steel sheets with and without sufficient magnetic domain refinement. The vertical axis represents the absolute value of the complex number of the FFT processing results (hereinafter referred to as the FFT intensity level), and the horizontal axis represents the value converted from the frequency obtained by the FFT processing results to the wavelength. Figure 5 As shown in (b), in the grain-oriented electromagnetic steel sheet where the magnetic domain refinement process is insufficient, the FFT intensity level near the wavelength of 8.0 mm is small. Figure 5 As shown in (a), the FFT intensity level near a wavelength of 8.0 mm increases in grain-oriented electromagnetic steel sheets with sufficient magnetic domain refinement. Furthermore, in this example, the FFT intensity level near a wavelength of 9.4 mm increases in both grain-oriented electromagnetic steel sheets with and without sufficient magnetic domain refinement, due to noise signals believed to originate from other equipment in the production line. Thus, the FFT intensity level also varies depending on the noise signal and the processing interval of magnetic domain refinement. Therefore, when using the intensity level at a specific wavelength as an indicator for determining whether magnetic domain refinement has been achieved, as in the method described in Patent Document 3, it may be impossible to accurately determine the state of magnetic domain refinement.

[0054] Therefore, in this embodiment, the information processing unit 13c calculates the judgment index with better accuracy as follows. First, the calculation range of the judgment index in the wavelength (frequency) direction is pre-set according to the interval of the magnetic domain refinement processing part. For example, when the magnetic domain refinement processing part is 8.0 mm apart, Figure 5 If the noise signal is near a wavelength of 9.4 mm, as in the examples shown in (a) and (b), the calculation range for the judgment index is set to a wavelength range of 7.0 to 9.0 mm. The calculation range for the judgment index is preferably set so that the spacing between the domain-refined portions is always within this range and that peaks of the noise signal caused by variations in other equipment or manufacturing conditions are not within this range. Figure 6 express Figure 5 The FFT intensity level of the calculation range of the judgment index in the examples shown in (a) and (b).

[0055] Next, the information processing unit 13c calculates the signal value (S) and the noise value (N) based on the FFT intensity level within the set calculation range. The signal value (S) can be the maximum value of the FFT intensity level within the calculation range, or the sum of the FFT intensity levels before and after three points at a wavelength equivalent to the interval between the magnetic domain refinement processing sections. Alternatively, the noise value (N) can be the average value of the FFT intensity level within the calculation range, or a predetermined fixed value. Furthermore, the calculation ranges for the signal value (S) and the noise value (N) can be determined within different ranges. Finally, the information processing unit 13c calculates the ratio (S / N) of the signal value (S) to the noise value (N) as a judgment indicator. This eliminates the influence of the peak value of the FFT intensity level caused by a previously known noise signal and reduces the influence of changes in the FFT signal level due to changes in a stable noise signal.

[0056] It was confirmed that this determination index has a high correlation with the difference between the planned and actual iron loss in an actual production line. Figure 7This is a graph that plots the correlation coefficient between the judgment index (leakage flux S / N value) and the difference ΔW between the planned and actual iron loss. Figure 7 In the example shown, the interval between the magnetic domain refinement processing parts is 8.0 mm, and the calculation range of the judgment index is the wavelength range of 7.0 to 9.0 mm. In addition, the signal value (S) is set to the maximum value of the FFT intensity level in the calculation range, and the noise value (N) is set to the average value of the FFT intensity level in the calculation range. Figure 7 As shown in FIG. 1 , it can be seen that there is a good correlation between the determination index and the difference ΔW between the planned and actual iron loss. Therefore, by using this determination index, the quality of the magnetic domain refining processing state can be determined with high accuracy.

[0057] In addition, it is preferable to prepare two-dimensional data of FFT intensity levels in the width direction and the length direction of the steel plate, and determine the magnetic domain refinement processing state based on the two-dimensional data of FFT intensity levels. Figure 8 As shown, when two processing machines are arranged in parallel in the width direction and magnetic domain refinement processing is performed across the entire width of the grain-oriented electromagnetic steel sheet, the first processing machine 1 corresponds to magnetic sensors with 1 to 5 channels, and the second processing machine 2 corresponds to magnetic sensors with 6 to 10 channels. Figure 13 This example shows a flow for creating two-dimensional data. In this example, measurement data for 10 channels in the width direction is available. First, in step S11, leakage flux output signals are collected at regular intervals along the length (for example, 32,768 points, a power of 2). Next, in step S12, a fast Fourier transform (FFT) operation is performed on each channel to calculate a frequency distribution, and an FFT intensity level is calculated for each channel. This operation is performed on a channel-by-channel basis, and the output signals of each channel are not summed in step S11, nor are the FFT results summed as in the method described in Patent Document 2 in step S12. Next, in step S13, the ratio (S / N) of the signal value (S) to the noise value (N) is calculated as a criterion based on the calculated FFT intensity level. Each channel is then classified based on this criterion. For channels whose criterion is between 0 and 8 (step S14), the FFT intensity level in the corresponding region of the two-dimensional data is set to "low" (step S15). On the other hand, for channels with a judgment index between 8 and 10 (step S16), the FFT intensity level in the corresponding two-dimensional data area is set to "medium" (step S17). Furthermore, for channels with a judgment index greater than 10 (step S18), the FFT intensity level in the corresponding two-dimensional data area is set to "high" (step S19). By repeating this process, two-dimensional data with FFT intensity levels of ten channels in the width direction and dozens of points in the length direction can be generated for a coil as a manufacturing unit.

[0058] The unstable magnetic domain refinement processing state is believed to be caused by deviations in the output, focus, scanning speed, and repetition interval (line spacing) of the laser or electron beam of the processing machine due to roller wear, etc. Alternatively, it is believed that the cause is the wobble of the grain-oriented electromagnetic steel sheet when the conveying speed of the grain-oriented electromagnetic steel sheet changes during processing. Furthermore, the unstable magnetic domain refinement processing state occurs continuously in the longitudinal direction within each processing machine. For example, if the focus adjustment of the processing machine is offset, the FFT intensity level in the longitudinal direction of multiple channels corresponding to a specific processing machine will continuously decrease. Furthermore, if the conveying speed changes, due to the wobble of the steel sheet, the intensity level in the longitudinal direction of multiple channels corresponding to a specific processing machine or multiple processing machines will also continuously decrease.

[0059] Therefore, in the index based on the measurement range of a frequency distribution, it is difficult to correctly judge the quality of the magnetic domain refinement processing state due to noise and deviation. However, by using two-dimensional data as described above, the quality of the magnetic domain refinement processing state can be judged with high precision. An example of judgment using data obtained in an actual production line is shown. As described above, it is assumed that there are 10 channels of magnetic sensors arranged in the width direction, but in fact the plate passes through 9 channels, namely channels 2 to 10. For example, as in the method described in Patent Document 2, an example of a case where the result of adding the FFT operation processing results of 9 channels is used as a judgment index to judge the magnetic domain refinement processing state is shown. Figure 9 If the threshold value of the FFT judgment index is 10 or more, it is judged as good, and less than 10, it is judged as bad. In this case, the magnetic domain refinement processing state is judged to be good. Figure 10 The following graph shows excerpts of the judgment indicators for 2, 4, 6, and 8 channels obtained from the same data. By evaluating each channel individually in the width direction, it is possible to determine that the magnetic domain refinement process is poor in the portion corresponding to 6 channels. In fact, in the steel plate shown in this data, the magnetic domain refinement process is poor in the corresponding width direction, resulting in poor iron loss.

[0060] In the determination using such two-dimensional data, a two-dimensional map of the FFT intensity level can be created for each coil as a manufacturing unit by displaying a calculated intensity level value using a color or the like. Figure 11As shown, if the FFT intensity level is displayed in red, yellow, green, etc., it is easy to visually determine whether the FFT intensity level is normally stable and high, or whether the FFT intensity level is low only in a single location, and whether the FFT intensity level is continuously low in a location corresponding to a specific processing machine during an abnormality. The threshold value of the FFT intensity level calculation value can be determined separately for each channel and manufacturing conditions. In addition, for two-dimensional data, it is also possible to create an automatic judgment, such as determining that an abnormality occurs when adjacent channels are below the threshold for a certain number of consecutive times. In this way, by using two-dimensional data to obtain a judgment index calculated based on the FFT operation processing results, the status of the magnetic domain refinement processing can be determined with high precision.

[0061] The closer the magnetic sensor is to the grain-oriented electromagnetic steel sheet, the higher the accuracy of leakage flux detection. However, due to contact caused by the vibration of the grain-oriented electromagnetic steel sheet, the actual distance (liftoff) between the magnetic sensor and the grain-oriented electromagnetic steel sheet is approximately 0.3 to 3 mm. If the detection signal deviates due to fluctuations in the liftoff, correction of the liftoff is necessary. It is also important to provide a distance meter (laser or eddy current type) to measure the distance between the magnetic sensor and the electromagnetic steel sheet to maintain leakage flux detection accuracy. Furthermore, if the vibration of the grain-oriented electromagnetic steel sheet is significant, it is possible to install a new conveyor roller, place a magnetizer adjacent to the existing roller, or incorporate the magnetizer into the existing roller. Furthermore, since the magnetization level applied to the grain-oriented electromagnetic steel sheet is low, an air-core coil can also be used as the magnetizer.

[0062] As apparent from the above description, a method for determining the processing state of a grain-oriented electromagnetic steel sheet according to one embodiment of the present invention applies a DC or AC magnetic field to a region of the grain-oriented electromagnetic steel sheet that has undergone magnetic domain refinement processing. The method detects leakage magnetic flux generated in the grain-oriented electromagnetic steel sheet in response to the application of the magnetic field for each of a plurality of regions in the width direction of the grain-oriented electromagnetic steel sheet. A frequency distribution for each region is calculated based on an output signal of the detected leakage magnetic flux in each region relative to its position in the longitudinal direction of the grain-oriented electromagnetic steel sheet. The magnetic domain refinement processing state is determined for each region based on an intensity level within a predetermined range of the frequency distribution for each region. Consequently, the magnetic domain refinement processing state of a specific portion of the steel sheet can be determined with high accuracy without requiring a great deal of effort.

[0063] Furthermore, by adjusting the state of the equipment for manufacturing the grain-oriented electrical steel sheet based on the magnetic domain refinement processing state of each region determined using the method for determining the processing state of the grain-oriented electrical steel sheet according to one embodiment of the present invention, the manufacturing yield of the grain-oriented electrical steel sheet can be improved. Specifically, Figure 12As shown, a two-dimensional map of FFT intensity levels is created (step S1), and the magnetic domain refinement state is determined based on the two-dimensional map (step S2). Locations on the sample determined to have poor magnetic domain refinement are then identified (step S3), and the state of manufacturing equipment, such as the electron gun, is adjusted based on the identification results (step S4). This improves the manufacturing yield of grain-oriented electrical steel sheets. Furthermore, for the same reasons as described above, a grain-oriented electrical steel sheet manufacturing facility equipped with a grain-oriented electrical steel sheet processing state determination device according to an embodiment of the present invention can improve the manufacturing yield of grain-oriented electrical steel sheets.

[0064] Furthermore, by controlling the magnetic domain refinement processing conditions based on the magnetic domain refinement processing state of each region determined using the processing state determination method for grain-oriented electrical steel sheets according to one embodiment of the present invention, the manufacturing yield of grain-oriented electrical steel sheets can be improved. Specifically, by feeding back the determination results of the magnetic domain refinement processing state to the processing machine, the magnetic domain refinement processing state can be corrected in advance, thereby avoiding the production of grain-oriented electrical steel sheets that deviate from specifications and improving the manufacturing yield of grain-oriented electrical steel sheets.

[0065] Furthermore, by managing the quality of grain-oriented electrical steel sheets based on the state of magnetic domain refinement in each region, as determined using the method for determining the state of grain-oriented electrical steel sheets according to one embodiment of the present invention, it is possible to stably provide high-quality grain-oriented electrical steel sheets. Specifically, by classifying the grain-oriented electrical steel sheets by quality based on the results of the determination of the state of magnetic domain refinement, it is possible to stably provide high-quality grain-oriented electrical steel sheets.

[0066] While the embodiments to which the inventions completed by the present inventors are applied have been described above, the present invention is not limited to the description and drawings of these embodiments, which constitute part of the disclosure of the present invention. In other words, other embodiments, examples, and operational techniques developed by those skilled in the art based on these embodiments are all encompassed within the scope of the present invention.

[0067] Industrial applicability

[0068] According to the present invention, a method and apparatus for determining the processing state of grain-oriented electromagnetic steel sheets can be provided, which can accurately determine the magnetic domain refinement processing state within a specific range of the steel sheet without requiring extensive labor. Furthermore, according to the present invention, a method for adjusting and manufacturing equipment for grain-oriented electromagnetic steel sheets can be provided, which can manufacture grain-oriented electromagnetic steel sheets with a high yield. Furthermore, according to the present invention, a method for managing the quality of grain-oriented electromagnetic steel sheets can be provided, which can stably provide high-quality grain-oriented electromagnetic steel sheets. Furthermore, according to the present invention, equipment for manufacturing grain-oriented electromagnetic steel sheets can be provided, which can manufacture grain-oriented electromagnetic steel sheets with a high yield.

[0069] Description of Reference Numerals

[0070] 1. Processing status determination device for 10-oriented electromagnetic steel sheets

[0071] 2.12 Leakage flux detection unit

[0072] 2a, 12a magnetizer

[0073] 2b, 12b magnetic sensors

[0074] 3.13 Signal Processing Unit

[0075] 13a amplifier

[0076] 13b Bandpass Filter (BPF)

[0077] 13c Information Processing Department

[0078] 14 Excitation power supply

[0079] S-oriented electrical steel sheet

[0080] SP magnetic domain refinement processing department.

Claims

1. A method for determining the processing state of a grain-oriented electromagnetic steel sheet, comprising: a magnetizing step of applying a DC or AC magnetic field to the region of the grain-oriented electromagnetic steel sheet where the magnetic domain refinement process has been performed; a detecting step of detecting, for each of a plurality of regions in a width direction of the grain-oriented electromagnetic steel sheet, a leakage magnetic flux generated in the grain-oriented electromagnetic steel sheet due to application of the magnetic field; a calculating step of calculating a frequency distribution of each region based on an output signal corresponding to a position in the longitudinal direction of the grain-oriented electromagnetic steel sheet in the leakage magnetic flux of each region detected in the detecting step; and The determination step determines the state of the magnetic domain refining process for each of the regions based on a determination index calculated from the intensity level within a predetermined range of the frequency distribution of each region.

2. The method for determining the processing state of a grain-oriented electromagnetic steel sheet according to claim 1, wherein: The predetermined range is set based on the interval of the magnetic domain refining process.

3. The method for determining the processing state of a grain-oriented electromagnetic steel sheet according to claim 1 or 2, wherein: The determining step includes determining a state of the magnetic domain refining process based on a two-dimensional distribution of the strength level in an in-plane direction of the grain-oriented electromagnetic steel sheet.

4. A device for determining the processing state of a grain-oriented electromagnetic steel sheet, comprising: A magnetizer applies a DC or AC magnetic field to the area of ​​the grain-oriented electromagnetic steel sheet where the magnetic domain refinement process has been performed. a plurality of magnetic sensors for detecting leakage magnetic flux generated in the grain-oriented electromagnetic steel sheet due to application of the magnetic field, for each of a plurality of regions in a width direction of the grain-oriented electromagnetic steel sheet; and A signal processing unit calculates a frequency distribution of each region based on output signals relative to positions in the longitudinal direction of the grain-oriented electromagnetic steel sheet in the leakage magnetic flux of each region detected by the plurality of magnetic sensors, and determines a state of the magnetic domain refinement processing for each region based on a determination index calculated based on an intensity level within a predetermined range of the frequency distribution of each region.

5. The processing state determination device of a grain-oriented electromagnetic steel sheet according to claim 4, wherein: The predetermined range is set based on the interval of the magnetic domain refining process.

6. The processing state determination device for a grain-oriented electromagnetic steel sheet according to claim 4 or 5, wherein: The signal processing unit determines a state of the magnetic domain refining process based on a two-dimensional distribution of the strength level in an in-plane direction of the grain-oriented electromagnetic steel sheet.

7. A method for adjusting equipment for manufacturing grain-oriented electromagnetic steel sheets, comprising: A step of adjusting a state of a grain-oriented electrical steel sheet manufacturing facility based on a state of magnetic domain refining processing in each of the regions determined using the method for determining a processing state of a grain-oriented electrical steel sheet according to any one of claims 1 to 3.

8. A method for manufacturing a grain-oriented electromagnetic steel sheet, comprising: A step of controlling the conditions of the magnetic domain refining processing based on the state of the magnetic domain refining processing in each of the regions determined using the method for determining the processing state of a grain-oriented electrical steel sheet according to any one of claims 1 to 3.

9. A quality management method for a grain-oriented electromagnetic steel sheet, comprising: A step of performing quality control of the grain-oriented electrical steel sheet based on the state of magnetic domain refining processing in each of the regions determined using the method for determining the processing state of the grain-oriented electrical steel sheet according to any one of claims 1 to 3.

10. A manufacturing apparatus for a grain-oriented electromagnetic steel sheet, comprising: A processing state determination device for a grain-oriented electrical steel sheet according to any one of claims 4 to 6.

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