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

Abstract

A grain-oriented electrical steel sheet processing state determining method according to the present invention includes: a magnetization step for applying a DC or AC magnetic field to a region of a grain-oriented electrical steel sheet that has been subjected to magnetic domain refinement processing; a detection step for detecting leakage magnetic flux generated in the grain-oriented electrical steel sheet concomitant with 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 calculation step for calculating a frequency distribution in each region from an output signal relating to a position in a longitudinal direction of the grain-oriented electrical steel sheet, for the leakage magnetic flux of each region detected in the detection step; and a determination step for determining the state of the magnetic domain refinement processing for each region on the basis of a determination index calculated from an intensity level within a predetermined range for the frequency distribution in each region.

Description

[Technical field]

[0001] The present invention relates to a processing state determination method for grain-oriented electrical steel sheet, a processing state determination device, a manufacturing equipment adjustment method, a manufacturing method, a quality control method, and a manufacturing equipment. [Background technology]

[0002] The electromagnetic properties of electrical steel sheets are one of the important properties that affect product performance, and the evaluation items include iron loss, maximum magnetic permeability, magnetostriction, etc. Iron loss refers to the property that when an AC magnetic field is applied to an electrical steel sheet, magnetic energy is consumed as heat energy due to magnetic hysteresis and eddy currents, resulting in energy loss. Therefore, electrical steel sheets with low iron loss are more advantageous than electrical steel sheets with high iron loss because they have higher energy conversion efficiency. Technologies have been developed to reduce the iron loss of grain-oriented electrical steel sheets, one of which is the magnetic domain refining process, which reduces iron loss by introducing localized nonuniformity periodically in the rolling direction to the surface layer using physical methods to refine the width of the magnetic domains.

[0003] This magnetic domain refinement process is not limited to a method of providing a change in shape such as a hole or a groove in the surface layer, but may be a method of introducing a non-uniformity in the surface layer without a change in shape. This can be realized, for example, by a method of applying heat or pressure. More specifically, the non-uniformity can be introduced in the surface layer by a method of irradiating a laser, an electron beam, a plasma jet, or the like. In the grain-oriented electrical steel sheet, magnetic domains magnetized in the rolling direction parallel to the easy axis of magnetization are formed. However, in the non-uniform part of the surface layer created by the magnetic domain refinement process, magnetic domains magnetized in a direction different from the rolling direction are locally formed even if there is no damage or change in shape, and this discontinuity of magnetization causes magnetic domain refinement.

[0004] The method described in Patent Document 1 is known as a method for evaluating a magnetic domain refinement process using an electron beam. Specifically, the method described in Patent Document 1 evaluates the focal position shift of the electron beam based on the emission luminance distribution of the electron beam. In addition, the methods described in Patent Documents 2 and 3 are known as methods for evaluating the processing state of a magnetic domain refinement process. The method described in Patent Document 2 evaluates the magnetic domain refinement processing state using eddy currents, while the method described in Patent Document 3 evaluates the magnetic domain refinement processing state using leakage magnetic flux. Both methods perform fast Fourier transform arithmetic processing and evaluate the magnetic domain refinement processing state based on the intensity level of a wavelength corresponding to the magnetic domain refinement processing interval. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6398961 [Patent Document 2] Patent No. 6562055 [Patent Document 3] Patent No. 6607242 Summary of the Invention [Problem to be solved by the invention]

[0006] In the method described in Patent Document 1, the irradiation position of the electron beam needs to be imaged by an imaging device, but dirt or deposition due to processing may adhere to the lens of the imaging device or the window on the imaging path. For this reason, in order to stably evaluate the focal position shift of the electron beam, frequent maintenance of the imaging device, etc. is required, which requires a lot of effort. On the other hand, in the methods described in Patent Documents 2 and 3, the 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 may not necessarily be obtained due to signals from other equipment in the production line and variations in production conditions. For this reason, the magnetic domain refinement processing state may not be accurately determined. Furthermore, according to the methods described in Patent Documents 2 and 3, the quality of the magnetic domain refinement processing state of the entire steel sheet can be determined, but the quality of the magnetic domain refinement processing state in a specific range of the steel sheet, such as only a certain part of the steel sheet in the width direction, cannot be determined.

[0007] The present invention has been made to solve the above problems, and an object of the present invention is to provide a method and device for determining the processed state of grain-oriented electrical steel sheet that can accurately determine the magnetic domain refinement processed state in a specific area of ​​the steel sheet without requiring much labor. Another object of the present invention is to provide a method for adjusting and manufacturing equipment for grain-oriented electrical steel sheet that can manufacture grain-oriented electrical steel sheet with a good yield. Another object of the present invention is to provide a quality control method for grain-oriented electrical steel sheet that can stably provide high-quality grain-oriented electrical steel sheet. Another object of the present invention is to provide manufacturing equipment for grain-oriented electrical steel sheet that can manufacture grain-oriented electrical steel sheet with a good yield. [Means for solving the problem]

[0008] [1] The method for determining the processing state of an electrical steel sheet according to the present invention includes a magnetization step of applying a DC or AC magnetic field to an area of ​​a grain-oriented electrical steel sheet which has been subjected to magnetic domain refinement processing; a detection step of detecting leakage magnetic flux generated in the grain-oriented electrical steel sheet as a result of application of the magnetic field for each of a plurality of areas in the width direction of the grain-oriented electrical steel sheet; a calculation step of calculating a frequency distribution of each area from an output signal for a position in the longitudinal direction of the grain-oriented electrical steel sheet, in the leakage magnetic flux of each area detected in the detection step; and a determination step of determining the state of the magnetic domain refinement processing for each of the areas based on a determination index calculated from an intensity level within a predetermined range of the frequency distribution of each of the areas.

[0009] [2] The method for determining a processed state of an electromagnetic steel sheet according to the present invention is the method according to the above-mentioned [1], wherein the predetermined range is set based on an interval of the magnetic domain refining process.

[0010] [3] The method for determining the processing state of an electrical steel sheet according to the present invention is the above-mentioned [1] or [2], wherein the determination step includes a step of determining the state of the magnetic domain refinement processing based on a two-dimensional distribution of the strength level in the in-plane direction of the grain-oriented electrical steel sheet.

[0011] [4] The processing state determination device for electrical steel sheet according to the present invention comprises a magnetizer which applies a DC or AC magnetic field to an area of ​​a grain-oriented electrical steel sheet which has been subjected to magnetic domain refinement processing, a plurality of magnetic sensors which detect leakage magnetic flux generated in the grain-oriented electrical steel sheet due to application of the magnetic field in each of a plurality of areas in the width direction of the grain-oriented electrical steel sheet, and a signal processing unit which calculates a frequency distribution for each area from output signals corresponding to a position in the longitudinal direction of the grain-oriented electrical steel sheet for the leakage magnetic flux in each area detected by the plurality of magnetic sensors, and determines the state of the magnetic domain refinement processing for each of the areas based on a determination index calculated from an intensity level within a predetermined range of the frequency distribution for each of the areas.

[0012] [5] The device for determining a processed state of an electromagnetic steel sheet according to the present invention is the device according to the above-mentioned [4], wherein the predetermined range is set based on an interval of the magnetic domain refinement processing.

[0013] [6] The processing state determination device for electrical steel sheet according to the present invention is the above-mentioned [4] or [5], wherein the signal processing unit determines the state of the magnetic domain refinement processing based on the two-dimensional distribution of the strength level in the in-plane direction of the grain-oriented electrical steel sheet.

[0014] [7] A method for adjusting manufacturing equipment for grain-oriented electrical steel sheet according to the present invention includes a step of adjusting the state of the manufacturing equipment for grain-oriented electrical steel sheet based on the state of magnetic domain refinement processing for each region determined using any one of the processing state determination methods for grain-oriented electrical steel sheet [1] to [3] above.

[0015] [8] A method for manufacturing grain-oriented electrical steel sheet according to the present invention includes a step of controlling conditions for the magnetic domain refinement processing based on the state of the magnetic domain refinement processing for each of the regions determined using any one of the processing state determination methods for grain-oriented electrical steel sheet among the above [1] to [3].

[0016] [9] The quality control method for grain-oriented electrical steel sheet according to the present invention includes a step of performing quality control of the grain-oriented electrical steel sheet based on the state of magnetic domain refinement processing for each of the regions determined using any one of the processing state determination methods for grain-oriented electrical steel sheet among the above [1] to [3].

[0017]

[10] A manufacturing facility for grain-oriented electrical steel sheet according to the present invention includes the processing state determination device for grain-oriented electrical steel sheet according to any one of the above [4] to [6]. Effect of the Invention

[0018] The processing state determination method and processing state determination device for grain-oriented electrical steel sheet according to the present invention enable the magnetic domain refinement processing state of a specific portion of a steel sheet to be determined with high accuracy without requiring much labor. Also, the adjustment method for manufacturing equipment for grain-oriented electrical steel sheet and the manufacturing method according to the present invention enable grain-oriented electrical steel sheet to be manufactured with a high yield. Also, the quality control method for grain-oriented electrical steel sheet according to the present invention enables high-quality grain-oriented electrical steel sheet to be stably provided. Also, the manufacturing equipment for grain-oriented electrical steel sheet according to the present invention enables grain-oriented electrical steel sheet to be manufactured with a high yield. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an apparatus for determining the processed state of grain-oriented electrical steel sheet according to the present invention. [Diagram 2] FIG. 2 is a diagram showing a two-dimensional map of leakage magnetic flux detected from a grain-oriented electrical steel sheet with a good magnetic domain refinement processing state and a grain-oriented electrical steel sheet with a poor magnetic domain refinement processing state. [Diagram 3] FIG. 3 is a schematic diagram showing the configuration of an apparatus for determining the processed state of a grain-oriented electrical steel sheet according to an embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing the output signal of a magnetic sensor of a certain channel in an actual production line, converted into the measured position in the longitudinal direction of the grain-oriented electrical steel sheet. [Diagram 5] FIG. 5 is a diagram showing the results of FFT processing, in the direction of the easy axis of magnetization, of leakage flux measurement results of grain-oriented electrical steel sheets with sufficient magnetic domain refinement processing and grain-oriented electrical steel sheets with insufficient magnetic domain refinement processing. [Figure 6] FIG. 6 is a diagram showing FFT intensity levels in the calculation range of the decision index in the example shown in FIG. [Figure 7] FIG. 7 is a plot of the correlation coefficient between the judgment index and the predicted / actual difference in iron loss. [Figure 8] FIG. 8 is a diagram showing an example of the arrangement of a processing machine and a magnetic sensor. [Figure 9] FIG. 9 is a diagram showing an example of determination of the magnetic domain refining processing state using the FFT determination index. [Figure 10]FIG. 10 is a diagram showing an example of determination of the magnetic domain refining processing state using the FFT determination index. [Figure 11] FIG. 11 is a schematic diagram showing an example of a two-dimensional map of FFT intensity levels. [Figure 12] FIG. 12 is a flowchart showing the flow of a method for adjusting manufacturing equipment for grain-oriented electrical steel sheets according to one embodiment of the present invention. [Figure 13] FIG. 13 is a flowchart showing the flow of the process of creating two-dimensional data of FFT intensity levels. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The machining state determination method and machining state determination device of the grain-oriented electrical steel sheet according to the present invention determine the magnetic domain refinement processing state of the grain-oriented electrical steel sheet by measuring the leakage magnetic flux of the grain-oriented electrical steel sheet non-destructively and non-contactingly using the leakage magnetic flux method. In the manufacturing process of grain-oriented electrical steel sheet, the magnetic domain refinement processing process, in principle, means locally changing the magnetism of the grain-oriented electrical steel sheet. Therefore, if the area subjected to the magnetic domain refinement processing (hereinafter referred to as the magnetic domain refinement processed part) is considered as a locally magnetic discontinuous part, there is magnetic flux (leakage magnetic flux) leaking from the magnetic domain refinement processed part. In other words, the magnetic domain refinement processing state of the grain-oriented electrical steel sheet can be determined by measuring the leakage magnetic flux by the leakage magnetic flux method.

[0021] FIG. 1 is a schematic diagram showing the configuration of a processing state determination device for grain-oriented electromagnetic steel sheet according to the present invention. As shown in FIG. 1, the processing state determination device 1 for grain-oriented electromagnetic steel sheet according to 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 grain-oriented electromagnetic steel sheet S in the direction of the easy magnetization axis, and a magnetic sensor 2b. The leakage flux detection unit 2 is installed on the grain-oriented electromagnetic steel sheet S in a non-contact manner, and applies external magnetization to the grain-oriented electromagnetic steel sheet S passing under the leakage flux detection unit 2 and detects the leakage flux of the grain-oriented electromagnetic steel sheet S. The signal processing unit 3 determines the magnetic domain refinement processing state of the grain-oriented electromagnetic steel sheet S based on the leakage flux detected by the leakage flux detection unit 2. In FIG. 1, the symbol SP indicates a magnetic domain refinement processing unit.

[0022] 2(a) and (b) are two-dimensional maps of leakage magnetic flux detected from grain-oriented electrical steel sheets with good and poor magnetic domain refinement processing states, respectively. As shown in FIG. 2(a), streaky magnetic domain refinement processed parts can be confirmed in the grain-oriented electrical steel sheet with good magnetic domain refinement processing state. However, as shown in FIG. 2(b), streaky magnetic domain refinement processed parts cannot be clearly confirmed in the grain-oriented electrical steel sheet with poor magnetic domain refinement processing state. The iron loss value of grain-oriented electrical steel sheets with good magnetic domain refinement processing state is lower than that of grain-oriented electrical steel sheets with poor magnetic domain refinement processing state. Therefore, the iron loss value of grain-oriented electrical steel sheets can also be estimated based on the detection status of streaky magnetic domain refinement processed parts.

[0023] In general, magnetic domain refinement processing is performed in a direction perpendicular to the easy axis direction of magnetization. When judging the magnetic domain refinement processing state of a grain-oriented electrical steel sheet, a magnetic field is applied that is smaller than the magnetic field at which the width of the magnetic domains whose magnetization direction is parallel to the easy axis direction becomes the width of the magnetic domains in the magnetic domain refinement processing portion. In practical operation, the magnitude of the magnetic field to be applied according to the components and thickness of the grain-oriented electrical steel sheet is determined in advance by experiments and simulations, and when judging the magnetic domain refinement processing state, a magnetic field corresponding to the components and thickness of the grain-oriented electrical steel sheet to be judged is applied.

[0024] If the result of the judgment is that the magnetic domain refinement processed state of the grain-oriented electrical steel sheet is not in the desired state, the magnetic domain refinement processed state is corrected at an early stage by feeding back to the processing machine. This early correction makes it possible to avoid manufacturing grain-oriented electrical steel sheets that do not meet specifications and improve the manufacturing yield of grain-oriented electrical steel sheets. Specifically, when the magnetic domain refinement processed portion is formed using a laser or an electron beam, the magnetic domain refinement processed state of the grain-oriented electrical steel sheet is adjusted to the desired state by adjusting the output, focus, scanning speed, or the repetition interval (line interval) of the longitudinal distortion of the laser or electron beam, etc.

[0025] Hereinafter, a configuration and operation of an apparatus for determining a processing state of grain-oriented electrical steel sheet according to an embodiment of the present invention will be described.

[0026] 3(a) and (b) are schematic diagrams showing the configuration of a processing state determination device for grain-oriented electrical steel sheet according to one embodiment of the present invention. As shown in FIG. 3(a) and (b), a processing state determination device 10 for grain-oriented electrical steel sheet according to one embodiment of the present invention includes a leakage magnetic 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 integrally. In addition, in FIG. 3(a) and (b), the longitudinal direction of the grain-oriented electrical steel sheet S is the same as the rolling direction in FIG. 3(b). On the other hand, in FIG. 3(a) and (b), the width direction of the grain-oriented electrical steel sheet S is a direction perpendicular to the rolling direction in FIG. 3(b) in the drawings.

[0027] The leakage magnetic flux detection unit 12 includes a magnetizer 12a and a plurality of magnetic sensors 12b, and is disposed opposite to the upper surface of the grain-oriented electrical steel sheet S.

[0028] The magnetizer 12a applies external magnetization to the grain-oriented electromagnetic steel sheet S by using the excitation power (excitation frequency in the case of AC) supplied from the excitation power source 14. In this embodiment, the magnetic domain walls in the area where the magnetic domain refinement processing is not performed move, but the external magnetization is set to a 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) so that the magnetization direction of the magnetic domain in the area where the magnetic domain refinement processing is performed is not parallel to the magnetization easy axis. In this case, the magnetic flux density of the grain-oriented electromagnetic steel sheet S was 0 to 1.7 mT. The magnetizer 12a may be an electromagnet or may use a permanent magnet. Considering the thickness of the grain-oriented electromagnetic steel sheet S and fine adjustment of the lift-off, an electromagnet is considered to be easier to adjust. However, even if a permanent magnet is used, it can be applied by making the relative position between the magnetic sensor 12b and the permanent magnet separately adjustable.

[0029] The magnetic sensors 12b are arranged in the width direction of the grain-oriented electromagnetic steel sheet S. The magnetic sensors 12b detect leakage magnetic flux of the grain-oriented electromagnetic steel sheet S that occurs when external magnetization is applied to each of a plurality of regions (channels) in the width direction of the grain-oriented electromagnetic steel sheet S. When the external magnetization applied to the grain-oriented electromagnetic steel sheet S is an AC current, the leakage magnetic flux of the grain-oriented electromagnetic steel sheet S is detected by detecting the excitation frequency. In addition, at that time, it is preferable to adjust the phase of the detection signal. In this embodiment, the magnetic sensor 12b is configured by a TMR (tunnel effect type) sensor, and detects leakage magnetic flux components parallel to the surface of the grain-oriented electromagnetic steel sheet S. It is preferable to use a highly sensitive magnetic sensor as the magnetic sensor 12b, and a SQUID, an MI (magnetic impedance type), a Hall element, a GMR (magnetic resistance type), an E-type sensor in which a coil is wound around an E-type ferromagnetic core, or the like can be used.

[0030] The signal processing unit 13 includes an amplifier 13a, a plurality of band pass filters (BPFs) 13b, and an information processing unit 13c. The amplifier 13a amplifies the output signals of the plurality of magnetic sensors 12b and outputs the amplified signals to the corresponding BPFs 13b. The plurality of BPFs 13b extract output signals of a set frequency band from the output signal 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 plurality of BPFs 13b to determine the processing state of the magnetic domain refinement processing portion of the grain-oriented electrical steel sheet S for each of a plurality of regions (channels).

[0031] When using the skin effect to generate a magnetic flux distribution in the thickness direction of a grain-oriented electrical steel sheet, the AC leakage flux method using an AC current can also be applied. In this case, however, a separate AC processing circuit is required. If only the amplitude value of the output signal is to be evaluated, an absolute value circuit and a low-pass filter are sufficient as the AC processing circuit. If the amplitude value and phase of the output signal are to be evaluated, detection must be performed at the excitation frequency, so a detection circuit is required.

[0032] When the magnetic sensor 12b is used for measurement, the grain-oriented electromagnetic steel sheet S is moved relatively a predetermined length in the direction of the easy axis of magnetization. In this case, the grain-oriented electromagnetic steel sheet S may be moved a predetermined length by a conveying device or the like, or the magnetizer 12a and the magnetic sensor 12b may be moved a predetermined length on the grain-oriented electromagnetic steel sheet S by a moving device or the like, or the movements of the grain-oriented electromagnetic steel sheet S and the magnetic sensor 12b may be combined. In the present invention, the easy axis of magnetization 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 transported a predetermined length in the longitudinal direction (the rolling direction in FIG. 3(b)).

[0033] FIG. 4 is a diagram showing the output signal of the magnetic sensor 12b of a certain channel in an actual production line, converted into the measured position (unit: mm) in the longitudinal direction of the grain-oriented electromagnetic steel sheet S. In the example shown in FIG. 4, the detection pitch of the magnetic sensor 12b is 0.1268 mm / point, and magnetic domain refinement processed parts spaced 8.0 mm apart are detected as changes in the output signal. In this embodiment, frequency analysis is used as an example of a judgment index for such an output signal. In this case, it is preferable to adjust the predetermined length in the longitudinal direction so that the number of signals is such that frequency analysis can be performed appropriately. In the case of FIG. 4, 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 detection pitch conditions.

[0034] 5(a) and (b) are diagrams showing the results of FFT calculation processing in the direction of easy axis of magnetization of leakage flux measurement results of grain-oriented electrical steel sheets with sufficient magnetic domain refinement processing and grain-oriented electrical steel sheets with insufficient magnetic domain refinement processing. The vertical axis shows the complex number of the FFT calculation processing result expressed as an absolute value (hereinafter referred to as FFT intensity level), and the horizontal axis shows the frequency obtained as a result of the FFT calculation processing converted into wavelength. As shown in FIG. 5(b), the grain-oriented electrical steel sheet with insufficient magnetic domain refinement processing has a small FFT intensity level near the wavelength of 8.0 mm. In contrast, as shown in FIG. 5(a), the grain-oriented electrical steel sheet with sufficient magnetic domain refinement processing has a large FFT intensity level near the wavelength of 8.0 mm. In addition, in this example, the FFT intensity level is large near the wavelength of 9.4 mm in both grain-oriented electrical steel sheets with sufficient and insufficient magnetic domain refinement processing due to noise signals thought to be from other equipment in the production line. In this way, the FFT intensity level also changes depending on the noise signal and the processing interval of the magnetic domain refinement processing. For this reason, when the intensity level of a specific wavelength is used as an index for determining the magnetic domain refinement processing, as in the method described in Patent Document 3, there is a possibility that the state of the magnetic domain refinement processing cannot be determined with high accuracy.

[0035] Therefore, in this embodiment, the information processing unit 13c calculates a more accurate judgment index as follows. First, a calculation range of the judgment index in the wavelength (frequency) direction is set in advance according to the interval of the magnetic domain refinement processed parts. For example, when the magnetic domain refinement processed parts are spaced at 8.0 mm intervals and the noise signal is near a wavelength of 9.4 mm as in the example shown in Figs. 5(a) and (b), the calculation range of the judgment index is set to a wavelength range of 7.0 to 9.0 mm. This calculation range of the judgment index is desirably set so that the interval of the magnetic domain refinement processed parts is always within the range and the peak value of the noise signal due to the variation of other equipment and manufacturing conditions is not within the range. Fig. 6 shows the FFT intensity level of the calculation range of the judgment index in the example shown in Figs. 5(a) and (b).

[0036] Next, the information processing unit 13c calculates a signal value (S) and a noise value (N) from the FFT intensity level in the set calculation range. The signal value (S) may be the maximum value of the FFT intensity level in the calculation range, or may be the sum of three points before and after the FFT intensity level of the wavelength corresponding to the interval of the magnetic domain refinement processing part. The noise value (N) may be the average value of the FFT intensity level in the calculation range, or may be a predetermined fixed value. The calculation ranges of the signal value (S) and the noise value (N) may be set to 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 index. In this way, it is possible to eliminate the influence of the peak value of the FFT intensity level due to a noise signal that is known in advance, and to reduce the influence when the FFT signal level changes due to a steady change in the noise signal.

[0037] It was confirmed that this judgment index has a high correlation with the predicted / actual difference in iron loss in an actual manufacturing line. FIG. 7 is a plot of the correlation coefficient between the judgment index (leakage flux S / N value) and the predicted / actual difference in iron loss ΔW. In the example shown in FIG. 7, the interval between the magnetic domain refinement processing parts is 8.0 mm, and the calculation range of the judgment index is a wavelength range of 7.0 to 9.0 mm. In addition, the signal value (S) is the maximum value of the FFT intensity level in the calculation range, and the noise value (N) is the average value of the FFT intensity level in the calculation range. As shown in FIG. 7, it can be seen that there is a good correlation between the judgment index and the predicted / actual difference in iron loss ΔW. Therefore, by using this judgment index, it is possible to accurately determine whether the magnetic domain refinement processing state is good or bad.

[0038] It is also preferable to create two-dimensional data of FFT intensity levels in the width direction and the length direction of the steel sheet, and to determine the magnetic domain refinement processing state based on the two-dimensional data of the FFT intensity levels. Specifically, for example, when two processing machines are arranged in parallel in the width direction as shown in FIG. 8 and magnetic domain refinement processing is performed over the entire width of the grain-oriented electrical steel sheet, the first processing machine 1 corresponds to magnetic sensors with channels 1 to 5, and the second processing machine 2 corresponds to magnetic sensors with channels 6 to 10. An example of the flow of the two-dimensional data creation process is shown in FIG. 13. In this example, there is measurement data for 10 channels in the width direction, and first, in the process of step S11, the output signal of the leakage magnetic flux (for example, 32768 points, which is a power of 2) is collected at every certain length in the length direction. Next, in the process of step S12, a frequency distribution is calculated by performing a fast Fourier transform calculation process for each channel, and an FFT intensity level is calculated for each channel. At this time, the calculation is performed for each channel, and in the process of step S11, the output signals of each channel are not added, and in the process of step S12, the results of the FFT calculation process, as in the method described in Patent Document 2, are not added. Next, in the process of step S13, the ratio (S / N) of the signal value (S) to the noise value (N) is calculated as a judgment index from the calculated FFT intensity level, and each channel is classified based on the calculated judgment index. Then, for channels whose judgment index is in the range of 0 to 8 (step S14), the FFT intensity level in the corresponding two-dimensional data area is set to "low" (step S15). On the other hand, for channels whose judgment index is in the range of 8 to 10 (step S16), the FFT intensity level in the corresponding two-dimensional data area is set to "medium" (step S17). Also, for channels whose judgment index is 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 on FFT intensity levels, such as 10 channels in the width direction and several tens of points in the length direction, can be created for one manufacturing unit, the coil.

[0039] The cause of the unstable magnetic domain refinement processing state may be misadjustment of the output, focus, scanning speed, and longitudinal distortion repetition interval (line interval) of the laser or electron beam of the processing machine due to roll wear, etc. Another possible cause is fluttering of the directional magnetic steel sheet when the conveying speed of the directional magnetic steel sheet during processing changes. In addition, the unstable magnetic domain refinement processing state occurs continuously in the longitudinal direction for each processing machine. For example, when the focus of the processing machine is misadjusted, the FFT intensity level decreases continuously in the longitudinal direction in multiple channels corresponding to a specific processing machine. In addition, even if the cause is fluttering of the steel sheet when the conveying speed changes, the intensity level decreases continuously in the longitudinal direction in multiple channels corresponding to a specific processing machine or multiple processing machines.

[0040] Therefore, it is difficult to accurately judge the quality of the magnetic domain refinement processing state due to noise and variation with an index of a measurement range based on one frequency distribution. However, by using two-dimensional data as described above, the quality of the magnetic domain refinement processing state can be judged with high accuracy. An example of judgment using data obtained in an actual manufacturing line is shown. As described above, it is assumed that 10 channels of magnetic sensors are arranged in the width direction, and the plate actually passed through 9 channels, 2 to 10. For example, as in the method described in Patent Document 2, FIG. 9 shows an example of judging the magnetic domain refinement processing state using the sum of the FFT calculation processing results of 9 channels as a judgment index. If the threshold value of the FFT judgment index is 10 or more as good and less than 10 as bad, in this case, the magnetic domain refinement processing state is judged to be good. In contrast, FIG. 10 shows an excerpt of judgment indexes for 2 channels, 4 channels, 6 channels, and 8 channels obtained from the same data. By judging each channel in the width direction individually, it is possible to judge that the magnetic domain refinement processing state is bad in the part corresponding to the 6th channel. In fact, in the steel sheet of this data, the state of magnetic domain refining processing was not good in the relevant width direction, resulting in a state of poor iron loss.

[0041] In such a judgment using two-dimensional data, a two-dimensional map of FFT intensity levels may be created for each coil, which is a manufacturing unit, by displaying one intensity level calculation value in color, etc. For example, by displaying the FFT intensity level in red, yellow, green, etc. as shown in FIG. 11, it is possible to easily visually judge whether the FFT intensity level is stable and high under normal conditions, or whether there is only a single low FFT intensity level, or whether the FFT intensity level at a location corresponding to a specific processing machine is continuously low under abnormal conditions. The threshold value of the FFT intensity level calculation value can be determined separately for each channel or manufacturing condition. In addition, an automatic judgment may be created in which an abnormality is judged to exist when adjacent channels for two-dimensional data fall below the threshold value a certain number of times or more. In this way, by acquiring the judgment index calculated from the FFT calculation result as two-dimensional data, it is possible to accurately judge the status of the magnetic domain refinement processing.

[0042] The closer the magnetic sensor is to the oriented electromagnetic steel sheet, the higher the detection accuracy of the leakage magnetic flux is. However, due to contact caused by flapping of the oriented electromagnetic steel sheet, the distance between the magnetic sensor and the oriented electromagnetic steel sheet (lift-off amount) is actually about 0.3 to 3 mm. If the detection signal varies due to fluctuations in the lift-off amount, it is necessary to correct the lift-off amount. It is also important to install a distance meter (laser or eddy current type) that measures the distance between the magnetic sensor and the electromagnetic steel sheet in order to maintain the detection accuracy of the leakage magnetic flux. In addition, if the flapping of the oriented electromagnetic steel sheet is large, a new transport roll may be installed, a magnetizer may be placed adjacent to an existing roll, or a magnetizer may be placed inside an existing roll. In addition, since the magnetization level applied to the oriented electromagnetic steel sheet is small, an air-core coil may be used as the magnetizer.

[0043] As is clear from the above explanation, the method for determining the processed state of a grain-oriented electromagnetic steel sheet, which is 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 been subjected to magnetic domain refinement processing, detects leakage magnetic flux generated in the grain-oriented electromagnetic steel sheet as a result of the application of a magnetic field for each of a plurality of regions in the width direction of the grain-oriented electromagnetic steel sheet, calculates a frequency distribution for each region from an output signal for the detected leakage magnetic flux in each region relative to a position in the longitudinal direction of the grain-oriented electromagnetic steel sheet, and determines the magnetic domain refinement processing state for each region based on the intensity level within a predetermined range of the frequency distribution for each region, thereby making it possible to accurately determine the magnetic domain refinement processing state of a specific portion of the steel sheet without requiring much effort.

[0044] In addition, the manufacturing yield of grain-oriented electromagnetic steel sheets can be improved by adjusting the state of the manufacturing equipment for grain-oriented electromagnetic steel sheets based on the magnetic domain refinement processing state for each region determined by using the processing state determination method for grain-oriented electromagnetic steel sheets, which is one embodiment of the present invention. Specifically, as shown in FIG. 12, a two-dimensional map of FFT intensity levels is created (step S1), and the magnetic domain refinement processing state is determined based on the two-dimensional map (step S2). Then, the positions where the magnetic domain refinement processing state is determined to be poor are confirmed on the sample (step S3), and the state of the manufacturing equipment such as the electron gun is adjusted based on the confirmation result (step S4). This makes it possible to improve the manufacturing yield of grain-oriented electromagnetic steel sheets. Furthermore, for the same reason as above, the manufacturing yield of grain-oriented electromagnetic steel sheets can be improved by using the manufacturing equipment for grain-oriented electromagnetic steel sheets equipped with the processing state determination device for grain-oriented electromagnetic steel sheets, which is one embodiment of the present invention.

[0045] Furthermore, the manufacturing yield of grain-oriented electrical steel sheets can be improved by controlling the conditions of the magnetic domain refinement processing based on the magnetic domain refinement processing state for each region determined using the processing state determination method for grain-oriented electrical steel sheets according to one embodiment of the present invention. Specifically, the determination result of the magnetic domain refinement processing state is fed back to the processing machine to correct the magnetic domain refinement processing state at an early stage, thereby preventing the production of grain-oriented electrical steel sheets that do not meet specifications and improving the manufacturing yield of grain-oriented electrical steel sheets.

[0046] Furthermore, by performing quality control of grain-oriented electrical steel sheets based on the state of magnetic domain refinement processing for each region determined using the method for determining the processing 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 grain-oriented electrical steel sheets by quality based on the determination results of the magnetic domain refinement processing state, it is possible to stably provide high-quality grain-oriented electrical steel sheets.

[0047] Although the embodiments of the present invention have been described above, the present invention is not limited by the descriptions and drawings that form part of the disclosure of the present invention according to the present embodiments. In other words, other embodiments, examples, and operation techniques, etc., made by those skilled in the art based on the present embodiments are all included in the scope of the present invention. [Industrial Applicability]

[0048] According to the present invention, it is possible to provide a processing state determination method and processing state determination device for grain-oriented electrical steel sheet that can accurately determine the magnetic domain refinement processing state in a specific area of ​​the steel sheet without requiring much labor. Also, according to the present invention, it is possible to provide a method for adjusting manufacturing equipment for grain-oriented electrical steel sheet and a manufacturing method thereof that can manufacture grain-oriented electrical steel sheet with a good yield. Also, according to the present invention, it is possible to provide a quality control method for grain-oriented electrical steel sheet that can stably provide high-quality grain-oriented electrical steel sheet. Also, according to the present invention, it is possible to provide manufacturing equipment for grain-oriented electrical steel sheet that can manufacture grain-oriented electrical steel sheet with a good yield. [Explanation of symbols]

[0049] 1,10 Processing condition judgment device for grain-oriented electrical steel sheets 2,12 Leakage magnetic flux detector 2a,12a magnetizer 2b,12b Magnetic sensor 3,13 Signal processing section 13a Amplifier 13b Bandpass Filter (BPF) 13c Information Processing Section 14 Excitation power supply S-oriented electrical steel sheet SP Magnetic Area Subdivision Processing Department

Claims

1. a magnetization step of applying a DC or AC magnetic field to the region of the grain-oriented electrical steel sheet that has been subjected to the magnetic domain refinement process; a detection step of detecting leakage magnetic flux generated in the grain-oriented electrical steel sheet due to application of the magnetic field for each of a plurality of regions in a width direction of the grain-oriented electrical steel sheet; a calculation step of calculating a frequency distribution of each region from an output signal with respect to a position in a longitudinal direction of the grain-oriented electrical steel sheet, in the leakage magnetic flux of each region detected in the detection step; a determination step of determining a state of the magnetic domain refining processing for each of the regions based on a determination index calculated from an intensity level within a predetermined range of a frequency distribution of each of the regions; The method for determining the processing state of a grain-oriented electrical steel sheet includes:

2. The method for determining a processed state of a grain-oriented electrical steel sheet according to claim 1 , wherein the predetermined range is set based on an interval of the magnetic domain refinement processing.

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

4. A method for determining the processing state of a directional electromagnetic steel sheet as described in claim 2, wherein the judgment step includes a step of determining the state of the magnetic domain refinement processing based on a two-dimensional distribution of the strength level in the in-plane direction of the directional electromagnetic steel sheet.

5. a magnetizer that applies a DC or AC magnetic field to a region of the grain-oriented electrical steel sheet that has been subjected to magnetic domain refinement processing; a plurality of magnetic sensors for detecting leakage magnetic flux generated in the grain-oriented electrical steel sheet due to application of the magnetic field, for each of a plurality of regions in a width direction of the grain-oriented electrical steel sheet; a signal processing unit that calculates a frequency distribution of each region from output signals with respect to a position in the longitudinal direction of the grain-oriented electrical steel sheet in the leakage magnetic flux in each region detected by the multiple magnetic sensors, and judges a state of the magnetic domain refinement processing for each region based on a judgment index calculated from an intensity level within a predetermined range of the frequency distribution of each region; The processing state determination device for grain-oriented electrical steel sheet is provided with:

6. The device for determining a processed state of a grain-oriented electrical steel sheet according to claim 5 , wherein the predetermined range is set based on an interval of the magnetic domain refinement processing.

7. The device for determining a processed state of grain-oriented electrical steel sheet according to claim 5 , wherein the signal processing unit determines a state of the magnetic domain refinement processing based on a two-dimensional distribution of the strength level in an in-plane direction of the grain-oriented electrical steel sheet.

8. The processing state determination device for directional electromagnetic steel sheet described in Claim 6, wherein the signal processing unit determines the state of the magnetic domain refinement processing based on the two-dimensional distribution of the strength level in the in-plane direction of the directional electromagnetic steel sheet.

9. A method for adjusting manufacturing equipment for grain-oriented electrical steel sheet, comprising a step of adjusting a state of the manufacturing equipment for the grain-oriented electrical steel sheet based on the state of magnetic domain refinement processing for each region determined using the method for determining the processing state of grain-oriented electrical steel sheet according to any one of claims 1 to 4.

10. 5. A method for manufacturing a grain-oriented electrical steel sheet, comprising a step of controlling conditions for the magnetic domain refinement processing based on a state of the magnetic domain refinement processing for 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 4.

11. A quality control method for grain-oriented electrical steel sheet, comprising a step of performing quality control of the grain-oriented electrical steel sheet on the basis of a state of magnetic domain refinement processing for each region determined using the processing state determination method for grain-oriented electrical steel sheet according to any one of claims 1 to 4.

12. A manufacturing facility for grain-oriented electrical steel sheet, comprising the processing state determination device for grain-oriented electrical steel sheet according to any one of claims 5 to 8.

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