Sensitivity correction method, inspection device, and magnetic sensor group

Abstract

An inspection device (10) has a plate-passing section (11), a magnetizer, a plurality of magnetic sensors, a correction wiring, an adjustment mechanism (13), and a control section (14). The correction wiring is disposed at the same relative position with respect to the respective magnetic sensing sections of the plurality of magnetic sensors. The adjustment mechanism (13) can switch between retreat of the plurality of magnetic sensors from a detection position and displacement of the plurality of magnetic sensors to the detection position. The control section (14) previously acquires first output values of the respective plurality of magnetic sensors. The control section (14) retreats the plurality of magnetic sensors before a prescribed portion of an electromagnetic steel sheet passes through the positions of the magnetic sensors. The control section (14) starts energization of the correction wiring. The control section (14) acquires second output values of the respective plurality of magnetic sensors. The control section (14) displaces the plurality of magnetic sensors to the detection position after the prescribed portion passes. The control section (14) corrects measured values measured by the respective plurality of magnetic sensors based on the first output values and the second output values.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to Japanese Patent Application No. 2020-115939, filed on July 3, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to a sensitivity calibration method, an inspection device, and a magnetic sensor array, for calibrating the sensitivity of multiple magnetic sensors in an inspection device for evaluating steel plates. Background Technology

[0004] A known inspection device magnetizes a steel plate, such as a directional electromagnetic steel plate, detects leakage flux, and thereby evaluates the steel plate. For example, a known device measures the electromagnetic properties of a steel plate to evaluate iron loss in the directional steel plate (see Patent Document 1).

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-124266

[0006] In an apparatus for measuring the electromagnetic properties of steel plates, multiple magnetic sensors are arranged on a surface parallel to the plate to measure the electromagnetic flux along its entire width. Each sensor detects leakage flux. To accurately measure the overall electromagnetic properties of the steel plate, magnetic sensors with identical sensitivity are required. However, temperature variations and aging can cause sensitivity deviations among the sensors, leading to differences in measurement accuracy. Therefore, the sensitivity of the magnetic sensors needs to be adjusted appropriately, but the inherent sensitivity of each sensor is often different. Sensitivity adjustment must be performed individually for each sensor. One method is to prepare a standard sample and measure it using all sensors. However, this involves observing the output waveform while adjusting the sensitivity, which is time-consuming and labor-intensive. Therefore, this method requires significant effort to adjust the sensitivity of multiple sensors. Furthermore, using a single standard sample to calibrate multiple sensors simultaneously can lead to the influence of characteristic deviations within the standard sample. Additionally, sensitivity adjustment cannot be performed during the operation of an electromagnetic steel plate production line, necessitating a temporary halt to the production line, which is not optimal in terms of production efficiency. Summary of the Invention

[0007] Therefore, the purpose of this disclosure, made in view of the aforementioned problems of the prior art, is to provide a sensitivity calibration method, an inspection device, and a magnetic sensor assembly that can easily and reliably perform sensitivity calibration of magnetic sensors.

[0008] To address the aforementioned issues, the sensitivity calibration method based on the first viewpoint is a sensitivity calibration method for a steel plate inspection device. This inspection device has multiple magnetic sensors, which are respectively arranged near calibration wiring through which alternating current for calibration flows.

[0009] The aforementioned inspection device acquires the first output values ​​of each of the multiple magnetic sensors in advance by energizing the aforementioned calibration wiring with alternating current.

[0010] Before the specified portion of the steel plate passes the position of the aforementioned magnetic sensor in the direction of passage, the plurality of magnetic sensors are retracted from their detection positions of leakage flux on the steel plate, and alternating current is energized into the calibration wiring to obtain the second output value of each of the plurality of magnetic sensors.

[0011] After passing the position of the aforementioned magnetic sensor in the specified section, the aforementioned multiple magnetic sensors are displaced toward the aforementioned detection position, and the measured values ​​measured by the aforementioned multiple magnetic sensors are corrected based on the aforementioned first output value and the aforementioned second output value.

[0012] Furthermore, in the sensitivity correction method based on the second viewpoint,

[0013] The aforementioned calibration wiring is positioned in the same relative position to the respective magnetic sensing parts of the multiple magnetic sensors.

[0014] Furthermore, in sensitivity correction methods based on a third-viewpoint,

[0015] Each of the aforementioned magnetic sensors is individually connected to a plurality of amplifiers capable of gain adjustment.

[0016] Each of the aforementioned amplifiers is gain-adjusted such that, under the condition of energizing the aforementioned calibration wiring with alternating current, the output value of each of the aforementioned amplifiers becomes the same calibration value under at least one of the conditions of causing the aforementioned magnetic sensors to retract from the aforementioned detection position or the condition of removing the aforementioned steel plate from the aforementioned through plate section.

[0017] Furthermore, in sensitivity correction methods based on the fourth perspective,

[0018] The aforementioned inspection device corrects the measured values ​​of the plurality of magnetic sensors by multiplying the first output value by the second output value.

[0019] Furthermore, the inspection device based on the fifth viewpoint includes:

[0020] A through-plate section that allows the steel plate to pass through;

[0021] A magnetizer that magnetizes the aforementioned steel plate;

[0022] Multiple magnetic sensors are arranged at different positions in a plane perpendicular to the lift-off direction, and the leakage magnetic flux generated in the steel plate magnetized by the magnetizer is detected.

[0023] The calibration wiring is arranged in the same relative position with respect to the magnetic sensing parts of the plurality of magnetic sensors mentioned above;

[0024] An adjustment mechanism is available to switch the retraction of the plurality of magnetic sensors from the detection position of the leakage magnetic flux of the steel plate, and the displacement of the plurality of magnetic sensors toward the detection position; and

[0025] The control unit controls the supply of alternating current to the aforementioned calibration wiring and the driving of the aforementioned adjustment mechanism.

[0026] The control unit acquires the first output values ​​of each of the multiple magnetic sensors in advance by energizing the calibration wiring with alternating current.

[0027] Before the magnetic sensors pass through the designated portion of the steel plate through the aforementioned through-plate section in the direction of passage, the plurality of magnetic sensors are retracted from the detection position of leakage magnetic flux of the steel plate, and alternating current is energized to the calibration wiring to obtain the second output value of each of the plurality of magnetic sensors.

[0028] After passing the position of the aforementioned magnetic sensor in the specified section, the aforementioned multiple magnetic sensors are displaced toward the aforementioned detection position, and the measured values ​​measured by the aforementioned multiple magnetic sensors are corrected based on the aforementioned first output value and the aforementioned second output value.

[0029] Furthermore, in the inspection device based on the sixth viewpoint,

[0030] The aforementioned calibration wiring is positioned in the same relative position to the respective magnetic sensing parts of the multiple magnetic sensors.

[0031] In addition, the steel plate inspection device based on the seventh viewpoint includes:

[0032] A through-plate section that allows the steel plate to pass through;

[0033] A magnetizer that magnetizes the aforementioned steel plate;

[0034] Multiple magnetic sensors are arranged at different positions in a plane perpendicular to the lift-off direction, and the leakage magnetic flux generated in the steel plate magnetized by the magnetizer is detected.

[0035] The calibration wiring is arranged at the same relative position with respect to the magnetic sensing parts of each of the plurality of magnetic sensors; and

[0036] The control unit controls the alternating current supplied to the aforementioned calibration wiring.

[0037] Furthermore, the magnetic sensor group based on the eighth viewpoint possesses:

[0038] A substrate having a magnetic sensor and having wiring formed in the vicinity of the magnetic sensor; and

[0039] One or more wirings connect multiple of the aforementioned substrates to each other.

[0040] According to the sensitivity calibration method, inspection device, and magnetic sensor group of this disclosure configured as described above, the sensitivity of the magnetic sensor can be calibrated in a way that reduces the decrease in the measurement accuracy of the overall electromagnetic properties of the electromagnetic steel plate. Attached Figure Description

[0041] Figure 1 This is a simplified diagram of the inspection device according to this embodiment.

[0042] Figure 2 It is to be from Figure 1 The simplified structure of the signal processing unit, which processes the output value of the leakage flux detection unit, is shown in the functional block diagram along with the simplified structure of the leakage flux detection unit.

[0043] Figure 3 It means Figure 2 A configuration diagram of multiple magnetic sensors in a magnetizer.

[0044] Figure 4 It's set. Figure 3 An external view of the printed circuit board for multiple magnetic sensors.

[0045] Figure 5 It is used for Figure 2 A flowchart illustrating the offline calibration process performed by the control unit.

[0046] Figure 6 It is used for Figure 2 The flowchart illustrates the online inspection process performed by the control department.

[0047] Figure 7 It is used for Figure 2 The flowchart illustrates the online calibration subroutine executed by the control unit. Detailed Implementation

[0048] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0049] Figure 1This is a simplified diagram of an inspection apparatus 10 according to one embodiment of the present disclosure. The inspection apparatus 10 includes: a through-plate section 11, a leakage flux detection section 12, an adjustment mechanism 13, and a control section 14. The inspection apparatus 10, for example, measures the electromagnetic properties of a steel plate, thereby evaluating the processing status in a magnetic domain subdivision processing step of the steel plate. Furthermore, it will... Figure 1 The area above the inspection device 10 is referred to as the upper part, and the area below it is referred to as the lower part.

[0050] The through-plate section 11 allows the steel plate 15 to pass in a passing direction parallel to the plate surface. The steel plate 15 is, for example, a directional electromagnetic steel plate. In this embodiment, the through-plate section 11 includes a first conveyor roller 16, a second conveyor roller 17, and a third conveyor roller 18. The first conveyor roller 16, the second conveyor roller 17, and the third conveyor roller 18 are axially supported, parallel to each other, and can rotate freely. The third conveyor roller 18 is axially supported below the first conveyor roller 16 and the second conveyor roller 17. The steel plate 15 can be clamped between the first conveyor roller 16 and the second conveyor roller 17 and the third conveyor roller 18. Alternatively, the steel plate 15 can be passed in the passing direction by rotating at least one of the first conveyor roller 16, the second conveyor roller 17, and the third conveyor roller 18 by means of an electric motor or the like.

[0051] The first conveyor roller 16, the second conveyor roller 17, and the third conveyor roller 18, as described above, prevent contact between the steel plate 15 and the leakage flux detection unit 12 caused by the swaying of the steel plate 15, and prevent noise from being mixed in due to lift-off movement. The first conveyor roller 16, the second conveyor roller 17, and the third conveyor roller 18 are, for example, rubber rollers. By using rubber rollers, slippage between them and the steel plate 15 and magnetic influence on the leakage flux detection unit 12 can be prevented.

[0052] like Figure 2 As shown, the leakage flux detection unit 12 includes a magnetizer 19 and a magnetic sensor group 20.

[0053] Magnetizer 19 externally magnetizes steel plate 15. Magnetizer 19 externally magnetizes steel plate 15, for example, using excitation power supplied from excitation power supply 21. In this embodiment, magnetizer 19 externally magnetizes steel plate 15 to the extent that the magnetic walls of magnetic domains in regions where magnetic domain subdivision processing has not been performed move, but the magnetization direction of magnetic domains in regions where magnetic domain subdivision processing has been performed is not parallel to the easy magnetization axis.

[0054] like Figure 3As shown, the magnetic sensor group 20 includes a plurality of magnetic sensors 22. The plurality of magnetic sensors 22 are arranged at different positions between the magnetic poles of the magnetizer 19, in a plane perpendicular to the lift-off direction, in other words, in a plane parallel to the surface of the steel plate 15 through which the through-plate section 11 passes. In this embodiment, the plurality of magnetic sensors 22 are arranged in a straight line at predetermined intervals along this plane in a direction perpendicular to the passage direction. Here, lift-off is the distance between the steel plate 15 and the surface of the leakage flux detection section 12 opposite to the steel plate 15. A plurality of magnetic sensors 22, for example, five magnetic sensors 22, are grouped into a unit, and one magnetizer 19 is combined for each unit.

[0055] The magnetic sensor 22 is, for example, a magnetoresistive element or a Hall element. In this embodiment, the magnetic sensor 22 is a magnetoresistive element. The magnetic sensor 22 detects the leakage magnetic flux generated on the steel plate 15 magnetized by the magnetizer 19. In this embodiment, each magnetic sensor 22 is configured to detect the leakage magnetic flux component perpendicular to the surface of the steel plate 15. Then, the magnetic sensor 22 outputs a value, such as a voltage, of the leakage magnetic flux signal corresponding to the detected leakage magnetic flux.

[0056] like Figure 4 As shown, in this embodiment, each magnetic sensor 22 is mounted on a separate printed circuit board 23. That is, one magnetic sensor 22 is mounted on one printed circuit board 23. The printed circuit board 23 is provided with calibration lines 24 having straight-line extensions as pattern lines. For example, in a printed circuit board 23 for mounting a magnetic sensor 22 using a magnetoresistive element, the calibration line 24 is provided near one side of a rectangle. Furthermore, the magnetic sensor 22 is mounted at a position overlapping the calibration line 24 when viewed from the normal direction of the printed circuit board 23 surface. Each printed circuit board 23 has the same shape, and the calibration lines 24 are also arranged at the same position on each printed circuit board 23 with the same shape, thickness, and parity. The magnetic sensor 22 is also mounted at the same position on each printed circuit board 23.

[0057] In the magnetic flux leakage detection unit 12, multiple printed circuit boards 23 on which magnetic sensors 22 are mounted are arranged such that the edges of the boards with calibration wiring 24 overlap on the same straight line and the board surfaces are parallel. In the magnetic flux leakage detection unit 12, the multiple printed circuit boards 23 are arranged at a constant spacing P. In the magnetic flux leakage detection unit 12, the multiple printed circuit boards 23 are arranged such that the board surfaces are parallel to the lifting direction and perpendicular to the passage direction. Figure 3 As shown, in the leakage flux detection unit 12, when viewed from the sensor arrangement direction of the multiple printed circuit boards 23 arranged from the multiple magnetic sensors 22, the center line of the magnetic sensor 22 overlaps with the center line of the magnetizer 19.

[0058] like Figure 4As shown, between adjacent printed circuit boards 23, calibration wiring 24 is connected by conductors 25. Figure 2 As shown, the calibration wiring 24 of the two ends of the printed circuit boards 23 of the plurality of printed circuit boards 23 of the leakage flux detection unit 12 is connected to the AC power supply 26.

[0059] The magnetic sensor group 20 is connected to the signal processing unit 27. The signal processing unit 27 has multiple amplifiers 28, multiple bandpass filters 29, and an arithmetic unit 30. The number of amplifiers 28 and bandpass filters 29 is the same as the number of channels in the magnetic sensor group 20. Each magnetic sensor 22 is connected in series with an amplifier 28 and a bandpass filter 29.

[0060] Amplifier 28 amplifies the output value of magnetic sensor 22. The gain of amplifier 28 can also be adjusted manually by the operator. Bandpass filter 29 removes interference noise components from the output value of magnetic sensor 22 amplified by amplifier 28 and extracts the frequency band of the detected object. Each bandpass filter 29 outputs the extracted frequency band to the arithmetic unit 30. In addition, the bandpass filter 29 receives the frequency band to be extracted from sensitivity calibration pulse generator 32 or production line PLG 31. The pulse signal is switched by pulse signal switcher 33 from the input of bandpass filter 29 in either direction of sensitivity calibration pulse generator 32 or production line PLG 31.

[0061] Furthermore, the pulse signal output from the sensitivity calibration pulse generator 32 is determined based on the frequency of the AC magnetic field generated by the AC current flowing from the AC power supply 26 to the calibration wiring 24. Based on this pulse signal, the frequency band of the signal corresponding to the AC magnetic field that the bandpass filter 29 should extract is determined. The AC current supplied from the AC power supply 26 to the calibration wiring 24 is adjusted so that the output value of the magnetic sensor 22 is the same as the output value of the leakage magnetic flux of the magnetic sensor 22 relative to the steel plate 15. The pulse signal output from the production line PLG 31 corresponds to the constant spacing of the areas of the steel plate 15 where magnetic domain subdivision processing has been performed in the passing direction; based on this pulse signal, the frequency band of the leakage magnetic flux signal that the bandpass filter 29 should extract is determined.

[0062] The arithmetic unit 30 can be connected to a display. Under the control of the control unit 14, the arithmetic unit 30 sends the leakage flux signals output from each bandpass filter 29 as information to the display. The display shows the amplitude voltage values ​​output from each bandpass filter 29. The arithmetic unit 30 sends the amplitude voltage values ​​output from each bandpass filter 29 to the control unit 14 under the control of the control unit 14.

[0063] Under the control of the control unit 14, the arithmetic unit 30 performs A / D conversion on the leakage flux signal extracted by the entire bandpass filter 29 for each travel interval of the steel plate 15, based on the pulse signal output from the production line PLG 31. The arithmetic unit 30 corrects the leakage flux signal by multiplying the sensitivity correction correction value based on the online correction described later by the A / D converted leakage flux signal.

[0064] The arithmetic unit 30 evaluates the processing status of the magnetic domain subdivision processing section of the steel plate 15 based on the corrected leakage flux signal. For example, the arithmetic unit 30 can perform high-speed Fourier transform processing on discrete data within a constant interval of each channel to determine the frequency distribution of each channel, and then perform the evaluation. Alternatively, instead of high-speed Fourier transform processing, the arithmetic unit 30 can perform the evaluation by calculating the average amplitude of a sine curve formed by discrete data within a constant interval.

[0065] The adjustment mechanism 13 can retract the magnetic sensor group 20, or in other words, the multiple magnetic sensors 22, from the detection position of the leakage magnetic flux of the steel plate 15, and reset it to the detection position. The detection position is the position where the leakage magnetic flux of the steel plate 15 can be detected, or it can be the position where the magnetic sensors 22 are spaced relative to the steel plate 15, i.e., lifted away by a specified matching length.

[0066] like Figure 1 As shown, in this embodiment, the adjustment mechanism 13 includes a servo motor 34 and a ball screw 35. The servo motor 34 is mounted on the base 36 with its rotation axis parallel to the vertical direction. One end of the ball screw 35 is supported on the upper side of the servo motor 34. The other end of the ball screw 35 supports the leakage flux detection unit 12. By rotating the servo motor 34, the leakage flux detection unit 12, including the magnetic sensor group 20, can be retracted from the detection position and reset to the detection position.

[0067] The control unit 14 includes one or more processors. The processors can be general-purpose processors or dedicated processors for specific processing, but are not limited to these. Dedicated processors may also include application-specific integrated circuits (ASICs). The control unit 14 may also include programmable logic devices (PLDs). PLDs may also include field-programmable gate arrays (FPGAs). The control unit 14 controls various parts of the inspection device 10, including controlling the supply of alternating current to the calibration wiring 24 and controlling the drive adjustment mechanism 13.

[0068] The control unit 14 performs online checks, including offline and online calibration, by inputting operation data to input units including buttons, keyboards, and indicator devices. Hereinafter, the control of each part of the inspection device 10 based on the control unit 14 for performing offline calibration, online checks, and online calibration will be described.

[0069] Offline calibration is the adjustment of the magnetic sensor sensitivity without the steel plate manufacturing process. In other words, calibration is performed before the steel plate manufacturing begins or during production line maintenance.

[0070] In offline calibration, the control unit 14 controls the pulse signal switcher 33 to switch the input of the pulse signal to the bandpass filter 29 to the sensitivity calibration pulse generator 32. The control unit 14 causes the sensitivity calibration pulse generator 32 to generate a pulse signal. By outputting a pulse signal from the sensitivity calibration pulse generator 32 to the bandpass filter 29, the bandpass filter 29 can extract the band component from the voltage signal output by the self-amplifier 28 that has the same frequency band as the AC magnetic field energized to the calibration wiring 24.

[0071] In offline calibration, the control unit 14 further controls the AC power supply 26 to energize the calibration wiring 24 with AC current. By energizing the AC current, a concentric AC magnetic field is generated around the calibration wiring 24. The value of this AC current is set as a reference current value. Each magnetic sensor 22 detects the vertical component of the generated AC magnetic field. Each magnetic sensor 22 outputs a value corresponding to the detected AC magnetic field. The output value is amplified by an amplifier and sent to a bandpass filter 29. The signal output by the bandpass filter 29 is displayed, for example, on a display connected to the arithmetic unit 30.

[0072] The calibration wiring 24 on the printed circuit board 23 has the same shape, and the printed circuit boards 23 are interconnected by wires 25. Therefore, if the alternating current is the same, the same alternating magnetic field is generated on each printed circuit board 23. The value of the magnetic flux of the alternating magnetic field is theoretically determined by the value of the alternating current. Therefore, the magnetic flux is detected by the magnetic sensor and the difference from the theoretical value is calculated, thereby adjusting the sensitivity of the magnetic sensor 22.

[0073] In offline calibration, under the controlled state described above, the gain of each amplifier 28 is adjusted according to the output values ​​of each bandpass filter 29 displayed on the monitor, thereby adjusting the sensitivity of each magnetic sensor 22. Sensitivity adjustment can be performed automatically or by an operator. The gain of each amplifier 28 is adjusted so that its output value becomes the same calibration value.

[0074] Here, the output value of each amplifier 28 is called the first output value, and the adjustment value of the gain of each amplifier 28 is called the first adjustment value. Let V1 represent the first output value itself, and let V11, V12, ..., V1... n (n is the number of magnetic sensors) represents the first output value of each amplifier 28. Additionally, the gain of the amplifiers 28 that output the same correction value is represented by α1 as the first adjustment value, and denoted by α11, α12, ..., α1... n (n is the number of magnetic sensors) represents the first adjustment value for each amplifier 28. The first output value V1 of each amplifier 28 can also be adjusted to be exactly the same correction value. Alternatively, the first output values ​​can not be exactly the same, but rather V1≈V11≈V12≈…, ≈V1 n (n is the number of magnetic sensors). In particular, in the case of manual adjustment by an operator, the consistency may not be strictly uniform. Here, the first output value V1 may also be the average of the first output values ​​of each amplifier 28 after gain adjustment.

[0075] When the input unit detects an operation input indicating the end of offline calibration, the control unit 14 controls the arithmetic unit 30 to send a first output value, which is the calibration value, as information to the control unit 14. The control unit 14 stores the first output value received as information in its memory. Additionally, the control unit 14 controls the AC power supply 26 to stop supplying AC current to the calibration wiring 24.

[0076] The leakage flux of the steel plate is measured using a magnetic sensor 22 calibrated as described above. The leakage flux measurement is performed online while the steel plate is being passed through.

[0077] During online inspection, the control unit 14 requests the thickness information of the steel plate 15 to be measured from the production line control device 37. Based on the thickness information received from the production line control device 37, the control unit 14 controls the adjustment mechanism 13 so that the gap between the steel plate 15 and the leakage flux detection unit 12 is a predetermined lifting amount.

[0078] During online inspection, the control unit 14 further controls the pulse signal switcher 33 to switch the input of the pulse signal to the bandpass filter 29 to the production line PLG 31 side. By outputting a pulse signal from the production line PLG 31 to the bandpass filter 29, the bandpass filter 29 can extract the band component with the same frequency band as the leakage flux signal from the voltage signal output by the self-amplifier 28.

[0079] During online inspection, the control unit 14 further controls the excitation power supply 21 to direct the excitation current to the magnetizer 19. The magnetizer 19 externally magnetizes the steel plate 15 using the excitation current. In this state, if the steel plate 15 passes through the through plate section 11 to the leakage flux detection unit 12, the leakage flux generated on the magnetized steel plate 15 can be detected. The detected leakage flux signal is amplified by the amplifier 28, has interference noise components removed by the bandpass filter 29, and is then input to the arithmetic unit 30.

[0080] Online calibration is the adjustment of the sensitivity of the magnetic sensor performed during online inspection. For example, online calibration can be performed when a specified portion of the steel plate passes through the leakage flux detection unit 12.

[0081] During online inspection, the control unit 14 receives information about the position of a specified portion of the steel plate 15 in the passage direction. The specified portion can be arbitrarily determined; for example, it is preferably a portion where the magnetic sensor 22 is required to retract, such as a welded portion. A welded portion is a welded portion where two steel strips are connected by welding. The position of the specified portion of the steel plate 15 in the passage direction is determined, for example, based on the position of the specified portion in an image captured by a camera fixed in a specific position relative to the base 36 in a specific posture, or based on the position of the specified portion sent from the production line control device 37 and the passage speed of the plate-passing section 11.

[0082] If a predetermined portion in the travel direction reaches a predetermined position before passing the magnetic sensor 22, the control unit 14 begins online calibration. During online calibration, the control unit 14 controls the adjustment mechanism 13 before the position of the predetermined portion in the travel direction passes the position of the leakage flux detection unit 12, including the magnetic sensor 22, so that the leakage flux detection unit 12 retracts from the detection position.

[0083] During online calibration, the control unit 14 further controls the pulse signal switcher 33 to switch the input of the pulse signal to the bandpass filter 29 to the sensitivity calibration pulse generator 32. The control unit 14 causes the sensitivity calibration pulse generator 32 to generate a pulse signal. By outputting a pulse signal from the sensitivity calibration pulse generator 32 to the bandpass filter 29, the bandpass filter 29 can extract the band component from the voltage signal output by the self-amplifier 28 that has the same frequency band as the AC magnetic field energized to the calibration wiring 24.

[0084] Similar to offline calibration, even during online calibration, the control unit 14 controls the AC power supply 26 to energize the calibration wiring 24 of each magnetic sensor 22 with a predetermined reference current value. By energizing the AC current, a concentric AC magnetic field is generated around the calibration wiring 24, and each magnetic sensor 22 detects the perpendicular component of the AC magnetic field.

[0085] Based on the vertical component of the detected alternating magnetic field, each magnetic sensor 22 outputs a value corresponding to the detected alternating magnetic field. This output value is amplified by each amplifier 28 and sent to the bandpass filter 29. The output value of each amplifier 28 at this time is called the second output value. Let V2 represent the second output value itself, and let V21, V22, ..., V2... n (n is the number of magnetic sensors) represents the second output value of each amplifier 28.

[0086] In online calibration, the control unit 14 further controls the arithmetic unit 30 to send a second output value, amplified by the amplifier 28 and with interference noise removed by the bandpass filter 29, as information to the control unit 14. The control unit 14 divides the first output value stored in its memory by the second output value received as information, thereby calculating a sensitivity correction value for each bandpass filter 29. The control unit 14 may also use the average value obtained by sampling the second output value over a constant time period for calculating the sensitivity correction value. The control unit 14 stores the calculated sensitivity correction value in its memory in a manner that is recognizable by each bandpass filter 29.

[0087] When the control unit 14 reaches the position after passing the magnetic sensor 22 at the designated location in the travel direction, it controls the AC power supply 26 to stop the AC current flowing to the calibration wiring 24. The control unit 14 controls the adjustment mechanism 13 to move the leakage flux detection unit 12 towards the detection position. After the control unit 14 controls the adjustment mechanism 13, the online calibration ends and the online inspection restarts.

[0088] Typically, the welded section, as an example of a specified section, can exhibit deformation of the steel plate, such as bulges at the welded portion, which can lead to malfunctions such as damage to the magnetic sensor 22. If online calibration is performed while the leakage flux detection unit 12 is being moved to a safe location, no calibration time is required, thus improving productivity. Furthermore, online calibration can be completed within the specified section's passage time, allowing for measures such as slowing down the steel plate's passage speed during the online calibration period. Additionally, by performing online calibration every time the specified section passes the leakage flux detection unit 12, the calibration frequency of the magnetic sensor 22 increases, thereby maintaining a high level of measurement accuracy for the steel plate.

[0089] Here, the sensitivity of the magnetic sensor 22 will deviate from that during offline calibration due to temperature changes and aging, meaning that there will be a first output value V1 and a second output value V2. n Inconsistent situations. Therefore, using V1 and V2... nThe calculated sensitivity correction value for each bandpass filter 29 is used to adjust the output value B of each amplifier 22 during the restarted online check. Specifically, this is achieved by adjusting B' = B × (V1 / V2). n This can reflect the results of online calibration of the magnetic sensor.

[0090] In addition, during online calibration, the first output value V1 and the second output value V2 relative to the reference current value... n The difference becomes apparent, thus enabling gain adjustment of each amplifier 28 in offline calibration after online calibration. Gain adjustment of each amplifier 28 can also be performed using the second adjustment value α2 so that the values ​​in the online check after restarting are correct. For example, the first adjustment value α1 can also be multiplied by the sensitivity correction value (V1 / V2). n Therefore, a second adjustment value α2 is calculated for each bandpass filter 29, and the calculated value is used to adjust the gain of amplifier 28. In this case, the sensitivity correction value can also be reset to 1, for example.

[0091] Next, use Figure 5 The flowchart below explains the offline calibration process performed by the control unit 14 in this embodiment. The offline calibration process begins when the input unit of the control unit 14 detects an operation input requesting offline calibration.

[0092] In step S100, the control unit 14 drives the adjustment mechanism 13 to retract the leakage flux detection unit 12 from the detection position. After driving the adjustment mechanism 13, the process proceeds to step S101.

[0093] In step S101, the control unit 14 controls the pulse signal switcher 33 to switch the pulse signal input to the bandpass filter 29 to the sensitivity calibration pulse generator 32. After the switching, the process proceeds to step S102.

[0094] In step S102, the control unit 14 causes the sensitivity calibration pulse generator 32 to generate a pulse signal. After generation, the process proceeds to step S103.

[0095] In step S103, the control unit 14 controls the AC power supply 26 to energize the calibration wiring 24 with AC current. After energization is initiated, the process proceeds to step S104.

[0096] In step S104, the control unit 14 controls the arithmetic unit 30 to display the amplitude voltage value of the output value of each magnetic sensor 22 amplified by the amplifier 28 and with interference noise removed by the bandpass filter 29. After the display starts, the process proceeds to step S105.

[0097] In step S105, the control unit 14 determines whether the input unit detects an operation input to end offline calibration. Furthermore, during the process of displaying the amplitude voltage value from step S104 on the display, it is assumed, for example, that the gain was manually adjusted so that the output value of each bandpass filter 29 becomes the first output value V1. Additionally, it is assumed that after ending the gain adjustment, the user inputs an operation input to end offline calibration. If no operation input is received, the process returns to step S105. If an operation input is received, the process proceeds to step S106.

[0098] In step S106, the control unit 14 averages all amplitude voltage values ​​received from the arithmetic unit 30 from the output of the full bandpass filter 29 and calculates the first output value. After the calculation, the process proceeds to step S107.

[0099] In step S107, the control unit 14 stores the first output value calculated in step S106 in the memory of the control unit 14. After storage, the process proceeds to step S108.

[0100] In step S108, the control unit 14 controls the AC power supply 26 to stop the AC current flowing to the calibration wiring 24. After the power is stopped, the offline calibration process ends.

[0101] Next, in this embodiment, using Figure 6 The flowchart below explains the online check processing performed by the control unit 14. The online check processing begins when the input section of the control unit 14 detects an operation input request for an online check.

[0102] In step S200, the control unit 14 sends the thickness information of the steel plate 15, which is rotatably supported by the through plate section 11, to the production line control device 37. After sending, the process proceeds to step S201.

[0103] In step S201, the control unit 14 determines whether it has received plate thickness information from the production line control device 37. If not, the process returns to step S201. If the information is received, the process proceeds to step S202.

[0104] In step S202, the control unit 14 controls the adjustment mechanism 13 based on the plate thickness information confirmed in step S201, so that the leakage flux detection unit 12 descends to the predetermined lifting detection position.

[0105] In step S203, the control unit 14 controls the pulse signal switcher 33 to switch the input of the pulse signal to the bandpass filter 29 to the production line PLG 31 side. After the switch, the process proceeds to step S204.

[0106] In step S204, the control unit 14 sends the sensitivity correction value stored in the memory of the control unit 14 to the arithmetic unit 30. After sending, the process proceeds to step S205.

[0107] In step S205, the control unit 14 controls the excitation power supply 21 to apply excitation power to the magnetizer 19. After application, the process proceeds to step S206.

[0108] In step S206, the control unit 14 controls the arithmetic unit 30 to multiply the leakage flux signal by the sensitivity correction values ​​of each bandpass filter 29 sent in step S204, thereby correcting it. The leakage flux signal is the signal detected by each magnetic sensor 22, amplified by the amplifier 28, and has its interference noise removed by the bandpass filter 29. After correction, the process proceeds to step S207.

[0109] In step S207, the control unit 14 controls the arithmetic unit 30 to evaluate the processing status of the magnetic domain subdivision processing section of the steel plate 15 based on the leakage flux signal that was corrected in step S206. After the evaluation, the process proceeds to step S208.

[0110] In step S208, the control unit 14 determines whether the end of the steel plate 15 has reached the leakage flux detection unit 12. If the end has been reached, the online inspection process ends. If the end has not been reached, the process proceeds to step S209.

[0111] In step S209, the control unit 14 determines whether a designated portion of the steel plate 15 has reached the position before passing the magnetic sensor 22. If it has not reached the position, the process returns to step S202. If it has reached the position, the online calibration subroutine S300 begins.

[0112] Next, use Figure 7 The flowchart below describes the online calibration subroutine S300 executed by the control unit 14 in this embodiment.

[0113] In steps S301 to S304, the control unit 14 performs the same control as in steps S100 to S103 of the offline correction process. After the AC current is applied in step S304, the process proceeds to step S305.

[0114] In step S305, the control unit 14 reads the first output value from its memory. After reading, the process proceeds to step S306.

[0115] In step S306, the control unit 14 divides the first output value read in step S305 by the second output value, thereby calculating the sensitivity correction value for each bandpass filter 29. The second output value is the value output by each magnetic sensor 22, amplified by the amplifier 28, and with interference noise removed by the bandpass filter 29. After the calculation, the process proceeds to step S307.

[0116] In step S307, the control unit 14 stores the sensitivity correction value calculated in step S306 in the memory of the control unit 14. After storage, the process proceeds to step S308.

[0117] In step S308, the control unit 14 determines whether a designated portion of the steel plate 15 has passed the position of the magnetic sensor 22. If it has not passed, the process returns to step S308. If it has passed, the process proceeds to step S309.

[0118] In step S309, the control unit 14 controls the AC power supply 26 to stop the AC current flowing to the calibration wiring 24. After the power is stopped, the online calibration subroutine processing ends, and the process returns to step S202.

[0119] The inspection device 10 of this embodiment, with the structure described above, acquires the first output values ​​of each of the plurality of magnetic sensors in advance by energizing the calibration wiring 24 with alternating current. Before the predetermined portion of the steel plate 15 passes the position of the magnetic sensor 22 in the passage direction, the magnetic sensor 22 is retracted from the detection position, and alternating current is energized to the calibration wiring 24 to acquire the second output values ​​of each of the plurality of magnetic sensors 22. After the predetermined portion passes the position of the magnetic sensor 22, the magnetic sensor 22 is displaced towards the detection position, and the measured values ​​measured by each of the plurality of magnetic sensors 22 are corrected based on the first and second output values. Generally, in order to obtain good detection sensitivity, the magnetic sensor 22 is placed at a detection position with a small lift-off during the detection of leakage flux of the steel plate 15. On the other hand, when the predetermined portion passes, for example, there may be a situation where the bulge caused by welding or the like is greater than the lift-off, so the magnetic sensor 22 is retracted from the detection position. With the structure described above, the inspection device 10 performs sensitivity correction of the magnetic sensor 22 at a higher frequency, i.e., the predetermined portion passage frequency, during the inspection of the electromagnetic characteristics of the steel plate 15. Therefore, the inspection device 10 can perform sensitivity calibration of the magnetic sensor 22 in a way that reduces the decrease in the measurement accuracy of the overall electromagnetic properties of the steel plate 15.

[0120] Furthermore, in the inspection apparatus 10 of this embodiment, calibration wiring 24 is arranged at the same relative position to the magnetic sensing parts of each of the plurality of magnetic sensors 22. With this structure, the inspection apparatus 10 can precisely calibrate the sensitivity among the plurality of magnetic sensors 22.

[0121] Furthermore, in the inspection apparatus 10 of this embodiment, each of the plurality of magnetic sensors 22 is individually connected to a plurality of amplifiers 28 whose gain can be adjusted. The gain of each of the plurality of amplifiers 28 is adjusted such that the first output value V1 of each of the plurality of amplifiers 28 becomes the same correction value under at least one of the states in which the plurality of magnetic sensors 22 are retracted from the detection position and in the state in which the steel plate 15 is removed from the through plate portion 11. According to this structure, the inspection apparatus 10 can more precisely calibrate its sensitivity.

[0122] Furthermore, the inspection device 10 of this embodiment corrects the measured values ​​by multiplying the measured values ​​of the magnetic sensors 22 during online inspection by a sensitivity correction value, which is the first output value V1 divided by the second output value V2 output from the magnetic sensors 22 during online calibration. n The obtained value. According to this structure, by appropriately setting the first correction value V1 by the operator of the offline calibration, the inspection device 10 can converge the correction value of the measured value after online calibration to a range suitable for measuring the electromagnetic properties of the steel plate 15.

[0123] While this disclosure has been described with reference to the accompanying drawings and embodiments, it should be noted that various modifications and / or alterations can be readily made based on this disclosure by those skilled in the art. Therefore, it should be understood that such modifications and / or alterations are included within the scope of this invention. For example, the functions contained in various structural parts can be reconfigured in a theoretically non-contradictory manner, and multiple structural parts can be combined into one or divided.

[0124] For example, in this embodiment, a magnetic sensor 22 is mounted on a printed circuit board 23, but multiple magnetic sensors 22 can be mounted on a printed circuit board 23, or all magnetic sensors 22 can be mounted on a printed circuit board 23.

[0125] The magnetic sensors 22 can be arranged in a single column along the width of the steel plate 15 (perpendicular to the direction of travel), or they can be arranged in multiple columns along the width of the steel plate 15. In the latter case, viewed from above, if the magnetic sensors 22 are arranged in an alternating pattern, the entire width of the steel plate 15 can be inspected without gaps, which is therefore more preferable. However, since the magnetic sensors 22 are interconnected by wiring, when arranged in multiple columns, it is preferable to arrange the magnetic sensor group that was originally in a single column into multiple columns. This can also be done if all the magnetic sensors 22 can be connected continuously like a single stroke.

[0126] In addition, in this embodiment, the control unit 14 retracts the leakage flux detection unit 12 from the detection position when performing offline calibration, but it may not retract it. Even if the leakage flux detection unit 12 is not retracted from the detection position, as long as the gain of the amplifier 28 is adjusted with the steel plate 15 removed from the through plate 11, the same effect as in this embodiment can be obtained.

[0127] In this embodiment, the control unit 14 calculates the sensitivity correction value and stores it in the memory of the arithmetic unit 30 during online calibration. However, the second output value V2 during online calibration can also be stored in memory, and the sensitivity correction value can be calculated during subsequent online checks. Alternatively, the control unit 14 can instruct the arithmetic unit 30 to calculate the sensitivity correction value, but the control unit 14 can also calculate the sensitivity correction value and send it to the arithmetic unit 30.

[0128] In this embodiment, the control unit 14 corrects the measured value during online inspection by multiplying it by a sensitivity correction value during online calibration. This sensitivity correction value is calculated using a first output value V1 that has been adjusted to become the same correction value. However, the first output value may not be adjusted to become the same correction value. For example, offline calibration may be omitted, and the measured value of the signal output from the magnetic sensor 22 during online inspection may be corrected based on a second output value of the signal output from the magnetic sensor 22 during online calibration.

[0129] Furthermore, in this embodiment, the control unit 14 calculates the sensitivity correction value, but the arithmetic unit 30 may also calculate it based on the control of the control unit 14. Additionally, in this embodiment, the first output value V1 and the sensitivity correction value are stored in the memory of the control unit 14, but they may also be stored in the memory of the arithmetic unit 30.

[0130] Explanation of reference numerals in the attached figures

[0131] 10…Inspection device; 11…Pass-through section; 12…Leakage flux detection section; 13…Adjustment mechanism; 14…Control section; 15…Steel plate; 16…First conveyor roller; 17…Second conveyor roller; 18…Third conveyor roller; 19…Magnetizer; 20…Magnetic sensor group; 21…Excitation power supply; 22…Magnetic sensor; 23…Printed circuit board; 24…Correction wiring; 25…Wire; 26…AC power supply; 27…Signal processing section; 28…Amplifier; 29…Band-pass filter; 30…Arithmetic unit; 31…Production line PLG; 32…Sensitivity calibration pulse generator; 33…Pulse signal switcher; 34…Servo motor; 35…Ball screw; 36…Base; 37…Production line control device.

Claims

1. A sensitivity calibration method for an inspection device, the inspection device having multiple magnetic sensors disposed near calibration wiring through which alternating current for calibration flows, the inspection device performing online inspection by measuring leakage flux during passage through steel plates connected by welded sections. The sensitivity correction method is characterized in that, When the steel plate is not being passed through, the inspection device obtains the first output values ​​of each of the multiple magnetic sensors in advance by energizing the calibration wiring with alternating current. During the passage of the steel plate, before the welded portion of the steel plate passes the position of the magnetic sensor in the passage direction, the plurality of magnetic sensors are retracted from the detection position of leakage flux of the steel plate, and alternating current is started to be applied to the calibration wiring to obtain the second output value of each of the plurality of magnetic sensors. After the welded portion passes the position of the magnetic sensor, the plurality of magnetic sensors are displaced toward the detection position. Based on the first output value and the second output value, the measured values ​​measured by each of the plurality of magnetic sensors are corrected. The measured values ​​of the plurality of magnetic sensors are corrected by multiplying the first output value by the second output value.

2. The sensitivity correction method according to claim 1, characterized in that, The calibration wiring is positioned at the same relative position to the respective magnetic sensing parts of the multiple magnetic sensors.

3. The sensitivity correction method according to claim 1 or 2, characterized in that, Each of the plurality of magnetic sensors is individually connected to a plurality of amplifiers with adjustable gain. Each of the plurality of amplifiers is gain-adjusted such that the first output value of each of the plurality of amplifiers becomes the same correction value under at least one of the following conditions: either the plurality of magnetic sensors are retracted from the detection position or the steel plate is removed from the through plate section.

4. An inspection device, characterized in that, have: A through-plate section, wherein the through-plate section allows the steel plate to pass through; A magnetizer, which magnetizes the steel plate; Multiple magnetic sensors are arranged at different positions in a plane perpendicular to the lift-off direction, and the leakage magnetic flux generated by the steel plate magnetized by the magnetizer is detected. The calibration wiring is arranged at the same relative position with respect to the magnetic sensing parts of the plurality of magnetic sensors; An adjustment mechanism is available to switch the retraction of the plurality of magnetic sensors from the detection position of the leakage magnetic flux of the steel plate, and the displacement of the plurality of magnetic sensors toward the detection position; and The control unit controls the supply of alternating current to the calibration wiring and the driving of the adjustment mechanism. When the steel plate is not passing through the passage section, the control unit pre-acquires the first output values ​​of each of the multiple magnetic sensors by energizing the calibration wiring with alternating current. During the passage of the steel plate through the through-plate section, before the welded portion of the steel plate passes the position of the magnetic sensor in the passage direction, the plurality of magnetic sensors are retracted from the detection position of leakage flux of the steel plate, and alternating current is started to be supplied to the calibration wiring to obtain the second output value of each of the plurality of magnetic sensors. During the passage of the steel plate through the through plate section, after the welding section passes the position of the magnetic sensor, the plurality of magnetic sensors are displaced toward the detection position, and the measured values ​​measured by the plurality of magnetic sensors are corrected by multiplying the first output value by the second output value.

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