KR101085563B1 - Apparatus for detecting inclusions of cold rolled coil using the magnetic sensor - Google Patents

Abstract

The present invention relates to an apparatus for inspecting an inclusion of a cold rolled steel sheet, in particular, a magnetizing unit generating a magnetic field having a magnetization direction in one direction using a direct current, and magnetizing a region to be measured of the cold rolled steel sheet using the generated magnetic field; A first magnetic sensor array including n magnetic sensors spaced in a row at regular intervals, the first magnetic sensor array generating a first output signal corresponding to a leaked magnetic flux leaked from the magnetized measured region; A second output signal including n magnetic sensors spaced in a row at the same interval as the magnetic sensors of the first magnetic sensor array, and generating a second output signal corresponding to the leakage magnetic flux leaked from the magnetized measured area, wherein the first magnetic sensor A second magnetic sensor array spaced apart from and parallel to the array; And a data processor configured to receive a differential value of the first and second output signals and to quantify the distribution of the intensity of the leaked magnetic flux leaked from the magnetized measurement region, wherein the first and second magnetic sensor arrays include first and second outputs. It is characterized in that it is connected to transfer the differential value of the signal to the data processor.

Description

Apparatus for detecting inclusions of cold rolled coil using the magnetic sensor}

The present invention relates to an apparatus for detecting an inclusion of a cold rolled steel sheet using a magnetic sensor. More particularly, the present invention relates to an apparatus for detecting an inclusion of a cold rolled steel sheet that can efficiently extract only information on a leakage flux due to the presence of an inclusion or a defect.

Cold rolled steel sheet is a steel sheet made by washing hot rolled steel sheet with acid and then rolling at room temperature to have a uniform thickness, smooth surface and gloss, and have a good surface and good dimensional accuracy, flatness and formability. Therefore, it is widely used in home appliances, office equipment, home appliances such as refrigerators and washing machines, and kitchen appliances. However, inclusions that occur during the production process affect the mechanical properties of the final product, which in turn leads to product defects. Therefore, in order to produce high quality cold rolled steel sheets, a method of analyzing / evaluating the position, shape, size, and distribution of inclusions generated in the manufacturing process is required.

Non-destructive inspection of inclusions in cold rolled steel includes ultrasonic (ultraviolet) inspection, magnetic leakage flux inspection, and X-ray transmission.

Ultrasonic flaw detection is a method of detecting holes or inclusions having a diameter of 100 μm or less by a high frequency of about 30-100 MHz, and has a disadvantage in that the penetration depth of the ultrasonic wave is not deep due to the high frequency. Therefore, the ultrasonic flaw detection is not suitable for detecting the inclusions of the cold rolled steel sheet because the inclusion does not detect the inclusions when the inclusions are deep in the cold rolled steel sheet.

X-ray transmission is one of the effective methods for detecting metal inclusions, but X-ray transmission is difficult to distinguish cracks, holes, and inclusions, and the equipment used for X-ray transmission is too high. Larger, there is a problem that the cost required to operate the X-ray transmission equipment is high.

On the other hand, leak magnetic flux inspection is a method using the principle that a perturb of magnetic flux is generated by a discontinuity such as an inclusion when the object to be measured is magnetized near saturation magnetization. That is, the leak magnetic flux inspection is a method of detecting and measuring the magnetic flux leaking into the air by the inclusions, in order to detect the small inclusions should not only reduce the size of the magnetic sensor but also increase the spatial resolution of the sensor. However, in order to detect the inclusions of the cold rolled steel sheet, the leak magnetic flux inspection has to magnetize the cold rolled steel sheet to the saturation magnetization, and there is a problem in that the strength of the external magnetic field affects the magnetic sensor and degrades the inclusion inspection ability. Therefore, it is possible to detect small inclusions deep in the cold rolled steel sheet, and to detect the inclusions of the cold rolled steel sheet having high spatial resolution and insensitive to the influence of an external magnetic field.

The problem to be solved by the present invention is to provide an apparatus for detecting the inclusion of cold-rolled steel sheet that can efficiently extract only the information of the leakage flux due to the presence of inclusions or defects, and can minimize the influence on the external magnetic field. .

In order to solve the above problems, the present invention provides a magnetic field having a magnetization direction in one direction by using a direct current, and a magnetization unit for magnetizing the region to be measured of the cold rolled steel sheet using the generated magnetic field; A first magnetic sensor array including n magnetic sensors spaced in a row at regular intervals, the first magnetic sensor array generating a first output signal corresponding to a leaked magnetic flux leaked from the magnetized measured region; A second output signal including n magnetic sensors spaced in a row at the same interval as the magnetic sensors of the first magnetic sensor array, and generating a second output signal corresponding to the leakage magnetic flux leaked from the magnetized measured area, wherein the first magnetic sensor A second magnetic sensor array spaced apart from and parallel to the array; And a data processor configured to receive a differential value of the first and second output signals and to quantify the distribution of the intensity of the leaked magnetic flux leaked from the magnetized measurement region, wherein the first and second magnetic sensor arrays include first and second outputs. It is characterized in that it provides a cold rolling steel inclusion inspection device, characterized in that connected to transfer the differential value of the signal to the data processing unit.

Preferably, the inclusion inspection device of the cold rolled steel sheet, the first and second magnetic sensor array further comprises a transfer unit for transporting the cold rolled steel sheet or the magnetic sensor array to scan the leakage flux of the cold rolled steel sheet, the magnetizer The direction may be fixedly arranged to be generated in a direction parallel to the transfer direction of the cold rolled steel sheet, and the first and second magnetic sensor arrays may be fixedly disposed to be located in the generated magnetic field.

According to the present invention, only the information of the leakage magnetic flux due to the presence of inclusions or defects can be extracted efficiently, and the effect on the strength of the external magnetic field can be reduced.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals in the drawings denote like elements.

1 is a view for explaining the apparatus for detecting the inclusions of the cold rolled steel sheet according to an embodiment of the present invention.

Referring to FIG. 1, an apparatus for detecting an inclusion of a cold rolled steel sheet according to the present invention includes a magnetization unit 10, a first magnetic sensor array 31, and a second magnetic sensor array 32 that magnetize the cold rolled steel sheet 20. To include a magnetic sensor array 30, and a data processing unit 40, and may further include a transfer unit 50 for transferring a cold rolled steel sheet or a magnetic sensor array.

The magnetization unit 10 serves to magnetize the cold rolled steel sheet 20, which is the object to be measured, and generates a magnetic field having a magnetization direction in one direction by using a DC current. The magnetization unit 10 is disposed to be positioned above or below the cold rolled steel sheet, and the cold rolled steel sheet is magnetized by the magnetic field generated by the magnetization unit 10.

In the magnetized cold rolled steel sheet 20, magnetic flux is concentrated through the interior of the internal steel sheet 20, and a part of the magnetic flux leaks. On the other hand, when the cold rolled steel sheet 20 has inclusions 2 such as cracks 1, impurities or air holes, the magnetic flux passing through the inside of the cold rolled steel sheet 20 is caused by the cracks 1 or inclusions 2. Perturbed and leaked to the outside of the cold rolled steel sheet 20.

The magnetic sensor array 30 may include a first magnetic sensor array 31 and a second magnetic sensor array 32, and the first and second magnetic sensor arrays 31 and 32 may have a predetermined distance from the cold rolled steel sheet 20. It is arranged to lift off (lift off) by.

The first magnetic sensor array 31 includes n magnetic sensors arranged in a line, and each magnetic sensor is spaced apart from each other at regular intervals. Each magnetic sensor detects a leaked magnetic flux leaking in the region under measurement of the magnetized cold rolled steel sheet 20, and generates a first output signal corresponding to the leaked magnetic flux.

Meanwhile, similarly to the first magnetic sensor array 31, the second magnetic sensor array 31 also includes n magnetic sensors arranged in the same line as the first magnetic sensor array 31, and each magnetic sensor also includes Also arranged to be spaced apart from each other at regular intervals. The array spacing between each magnetic sensor in the second magnetic sensor array 32 is equal to the cast spacing in the first magnetic sensor array 31. In addition, the second magnetic sensor array 32 and the first magnetic sensor array 31 are positioned in parallel with each other at regular intervals.

The first and second magnetic sensor arrays 31 and 32 detect leakage magnetic flux leaking to the outside of the cold rolled steel sheet 20, respectively, and output values corresponding thereto. In the case where cracks (1) or inclusions (2) are present in the cold rolled steel sheet (20), the leakage magnetic flux leakage from the cold rolled steel sheet (20) increases or varies irregularly. Inclusions present at (20) can be inspected.

In the present invention, the first magnetic sensor array 31 and the second magnetic sensor array 32 are connected to output the differential value of the output signal to the data processor 40 to be described later.

The data processor 40 processes and analyzes differential values of the output signals of the first magnetic sensor array 31 and the second magnetic sensor array 32 in the magnetic sensor array 30 to determine whether the inclusions present in the cold rolled steel sheet exist. Detect.

The transfer unit 50 transfers the cold rolled steel sheet 20 in a linear direction, thereby allowing the magnetic sensor array 30 to scan the entire measurement area of the cold rolled steel sheet 20. The transfer unit 50 is composed of a plurality of driving rollers on which the cold rolled steel sheet 20 is mounted, a drive motor for rotating the same at a constant speed, and the like, as long as the cold rolled steel sheet is linearly transferred at a constant speed.

On the other hand, the conveyer 50 may be different from the cold rolled steel sheet 20, and the magnetization unit 10 and the sensor array 30 can be linearly transferred in a direction parallel to the magnetization direction. This embodiment is an embodiment in which the magnetic sensor array 30 and the magnetization portion 10 disposed between the two magnetic poles of the magnetization portion 10 together transfers together on the cold rolled steel sheet 20 in the direction parallel to the magnetization direction. Since the magnetic sensor array 30 disposed in the magnetic pole of the magnetization unit 10 is linearly transferred, the cold rolled steel sheet may be scanned as a whole.

As described above, the transfer unit 50 may transfer the cold rolled steel sheet 20 or the magnetic sensor array (the magnetic sensor array and the magnetization unit are transferred together) in a linear direction, where the transfer direction is parallel or perpendicular to the magnetization direction of the magnetization unit. Can be the direction. The functions of the magnetizer 10, the magnetic sensor arrays 31 and 32, and the data processor 40 will be described later.

2 (a) and 2 (b) are diagrams illustrating an apparatus for flaw detection of inclusions in a cold rolled steel sheet according to an embodiment of the present invention, respectively.

As shown, the magnetization unit 10 includes a yoke 11 and a coil 12, and a DC power is applied to the coil to generate a magnetic field having a magnetization direction in one direction. Due to the generated magnetic field, the cold rolled steel sheet 20 is also magnetized in the same magnetization direction.

The magnetic sensor array 30 including the first magnetic sensor array 31 and the second magnetic sensor array 32 is disposed between two magnetic poles of the magnetization unit 20, and the cold rolled steel sheet 20. Is fixedly arranged to be lifted off by a certain distance.

As shown in FIG. 2 (b), when the inclusions 2 are present inside the cold rolled steel sheet 20, the magnetic flux passing through the inside of the cold rolled steel sheet 20 is perturbed by the crack 1 or the inclusions 2. And leaks to the outside of the cold rolled steel sheet 20. In the absence of the inclusions 2, a certain amount of leakage magnetic flux exists, but in the presence of the inclusions 2, more magnetic fluxes leak. Therefore, the magnetic sensor array 30 may detect the presence or absence of the inclusion 2 in the cold rolled steel sheet 20 by analyzing the amount of change in the leakage magnetic flux.

3 (a) to 3 (f) are diagrams for explaining the principle of flaw detection of inclusions by leak magnetic flux detection, respectively.

FIG. 3 (a) is a schematic diagram for explaining the magnetic field distribution generated when detecting the inclusions 2 of the cold rolled steel sheet 20 using the magnetization unit 10. As shown in FIG.

The magnetic sensor array 30 and the cold rolled steel sheet 20 are spaced apart to have a constant lift-off, and a yoke type magnetizer is used as the magnetization unit 10.

If the magnetization direction is X, the direction perpendicular to the surface of the cold-rolled steel sheet 20 is Z, and the direction perpendicular to the XZ plane is Y, the magnetic sensor array 30 has a magnitude of the magnetic field strength H _Z of the Z-axis component. Outputs a proportional output signal V _H.

In the present invention, a magnetic sensor constituting the magnetic sensor array 30 may be a Hall sensor or a magnetoresistive sensor, and the Hall sensor and the magnetoresistive sensor may have a magnitude of a normal or planar component of a magnetic field incident on the sensor surface. An electrical signal is output in proportion.

Figure 3 (b) shows the magnetic field distribution of the leakage magnetic flux leaked to the outside in the cold rolled steel sheet, Figure 3 (c) shows the magnetic field distribution of the leakage magnetic flux leaked by the inclusions in the cold rolled steel sheet, Figure 3 (d) It is a figure which shows the whole magnetic field distribution in a steel plate.

When the cold rolled steel sheet 20 approaches the magnetization portion 10, the magnetic flux is concentrated through the steel sheet and a part of the cold rolled steel sheet 20 is leaked to the outside of the cold rolled steel sheet 20 (H _Z ^EXT ). The magnetic flux passing through the cold rolled steel sheet 20 is perturbed by inclusions (INC-1, INC-2, INC-3) and leaked into the air (H _Z ^{INC- 1} , H _Z ^INC-2 , H _Z ^{INC). -3} ). Therefore, the overall magnetic field distribution has a distribution of magnetic fields in which H _Z ^EXT , H _Z ^{INC -1} , H _Z ^INC-2 , and H _Z ^{INC -3} overlap as shown in FIG. 3 (d).

As described above, a magnetic sensor such as a hall sensor outputs an electrical signal V _H in linear proportion to the strength of the magnetic field. At this time, as the magnitude of the leakage magnetic flux H ^INC increases, the output V _H ^INC of the magnetic sensor also increases. In order to increase the leakage magnetic flux (H ^INC ) by the inclusions, the magnetization force must be increased. As the magnetization force increases, the output of the magnetic sensor according to the leakage magnetic flux (H ^EXT ) by the magnetization unit 10 (V _H ^EXT). ) Will also grow. Therefore, as shown in FIG. 3E, the magnetic sensor should have a wider dynamic range in order not to be saturated (V _H ^CRT ) by the magnetization unit 10. In addition, the magnetic sensor must have a high sensitivity at the same time to accurately detect the leakage flux by the inclusions.

The present invention provides a method of minimizing the influence of an external magnetic field and maximizing the output signal of the magnetic sensor due to leakage magnetic flux by inclusions.

As shown in FIG. 3 (b), the intensity H _Z ^EXT of the leaked magnetic flux generally leaked by the magnetization unit 10 has a substantially constant slope inside the magnetic pole. Therefore, the derivative value dH _Z ^EXT / dX in the X-direction is constant.

However, the differential value (dH _Z I ^NC / dX) in the X direction of the strength of the leakage magnetic flux H _Z ^INC due to inclusions is not constant, and the value changes in proportion to the size of the inclusion. Therefore, using this principle can minimize the influence of the external magnetic field and maximize the signal of the leakage flux due to the presence of inclusions.

On the other hand, the derivative value (dV _H / dX) of the magnetic sensor output is the magnetic sensor due to the leakage flux according to the derivative (dV _H ^EXT / dX) of the magnetic sensor output due to the general leakage flux and the inclusion as shown in [Equation 1] below. Sum of the derivative of the output (dV _H ^INC / dX).

In addition, as described above, the derivative of the magnetic field (dV _H ^EXT / dX) by the general leakage magnetic flux by the magnetization unit 10 is between the magnetic poles (X _{POLE -1} and X _{POLE -2} ) as shown in Equation 2 below. It is almost constant in the magnetization effective area of Nm, and can be set to be close to zero by the introduction of a bias voltage.

dV _H / dX can be approximated from the difference of adjacent output signal values as shown in Equation 3 below. Here, ΔX means the distance between the magnetic sensors or the spatial distance of the data comparison position.

In order to calculate dV _H / dX from Equation 3, the distribution of V _H should be stored and calculated. Accordingly, the output V _H ^EXT of the magnetic sensor is as shown in FIG. ^3E due to the influence of the leakage magnetic flux H ^EXT by the magnetization unit 10.

Therefore, in the present invention, in order to calculate the difference between V _H (X + ΔX, Y, Z) and V _H (X, Y, Z) expressed in Equation 3, X + ΔX and X as shown in FIG. Install a separate magnetic sensor at each position and obtain the differential value of the output signal of the magnetic sensor.

4 is a diagram illustrating a magnetic sensor array according to the present invention, in which the magnetic sensor array 30 includes a first magnetic sensor array 31 and a second magnetic sensor array 32.

As described above, the first magnetic sensor array 31 includes n magnetic sensors 31_1 to 31_n arranged in a row, and each magnetic sensor 31_1 to 31_n is spaced apart from each other at a constant interval M. . Each of the magnetic sensors 31_1 to 31_n respectively detects a leaked magnetic flux leaking from the magnetized cold rolled steel sheet 20 and generates a first output signal corresponding to the detected leaked magnetic flux. The first output signal is a set of output signals of the respective magnetic sensors 31_1 to 31_n.

Meanwhile, similarly to the first magnetic sensor array 31, the second magnetic sensor array 31 also includes n magnetic sensors 32_1 to 32_n arranged in a row, and each magnetic sensor 32_1 to 32_n is also the same. Spaced at intervals (M). The arrangement interval M of each of the magnetic sensors 32_1 to 32_n is the same as the arrangement interval M of the first magnetic sensor array 31. In addition, the first and second magnetic sensor arrays 31 and 32 are disposed in parallel with a predetermined distance L from each other. Each of the magnetic sensors 32_1 to 32_n respectively detects a leaked magnetic flux leaking from the magnetized cold rolled steel sheet 20 and generates a second output signal corresponding to the detected leaked magnetic flux. The second output signal is a set of output signals of the magnetic sensors 32_1 to 32_n.

In the magnetic sensor arrays 31 and 32, the arrangement distance M between the magnetic sensors, the separation distance L between the magnetic sensor arrays, and the lift off distance between the magnetic sensor array and the cold rolled steel sheet may be determined by the sensitivity and characteristics of the magnetic sensors. It can be appropriately adjusted according to the spatial resolution, the characteristics of the cold rolled steel sheet, and the feed rate / scan speed of the cold rolled steel sheet or the magnetic sensor array.

According to the present invention, by scanning the cold rolled steel sheet using a magnetic sensor arranged in an array form, it is possible to increase the inclusion inspection speed of the cold rolled steel sheet.

In addition, in the present invention, the first magnetic sensor array 31 and the second magnetic sensor array 32 are connected to output the differential value of the output signal to the data processor 40 which will be described later.

To this end, in the first and second magnetic sensor arrays 31 and 32, the first power terminal a of each of the magnetic sensors 31_1 to 31_n and 32_1 to 32_n is connected to the first power line V _CC , and In the first and second magnetic sensor arrays 31 and 32, the second power terminal b of each of the magnetic sensors 31_1 to 31_n and 32_1 to 32_n is connected to the ground line GND.

The first output terminal c of each of the magnetic sensors 31_1 to 31_n in the first magnetic sensor array 31 is connected to the data processor 40, and each magnetic sensor in the second magnetic sensor array 32. The first output terminal c of 32_1 to 32_n is connected to the data processor, and the second output terminal d of each of the magnetic sensors 31_1 to 31_n in the first magnetic sensor array 31 is located in the same row. 2 are respectively connected to the second output terminals d of the magnetic sensors 32_1 to 32_n of the magnetic sensor array 32.

In the structure of the magnetic sensor array 30 as shown in FIG. 4, no matter how large a magnetic field is generated in the Z-direction, the output signals output from the magnetic sensor array 30 are separated by two neighboring signals of the magnetic sensor arrays 31 and 32. Only the output signal difference of the sensors 31_n, 32_n, where n means the row number of the array, is shown. Therefore, the result as shown in FIG. 3 (f) can be expected, and the result obtained in the structure of the magnetic sensor array 30 according to the present invention also means the molecular value of Equation 3 above.

On the other hand, if the denominator value ΔX increases, the theoretical value of Equation 3 decreases, but in practice, the structure of FIG. Therefore, in this study, Equation 3 is modified and expressed as follows.

On the other hand, according to the dipole model (dipole model), the leakage magnetic flux from the inclusion having a length l _C , width w _C , depth d _C can be expressed by the following [Equation 5].

If the magnetic pole spacing is w _M , the length of the magnetic pole is l _M , and the height of the magnetic pole is d _M , the leakage flux distribution by the magnetizer is expressed by Equation 6 below.

On the other hand, assuming that the magnetic sensor is a Hall sensor, the Hall voltage is proportional to the sum of Equation 5 and Equation 6. Therefore, Equation 4 may be expressed as follows.

Here, k is a proportional constant representing the characteristics of the magnetic sensor (e.g., Hall constant) and the driving condition (e.g., Hall input voltage and amplification ratio).

The magnetic sensor array 30 according to the present invention is for the case where the cold rolled steel sheet 20 or the magnetic sensor array 30 is transported, and it is not necessary to increase the number of the array further. In addition, the Hall sensors arranged on the wafer are connected as shown in FIG. 4, and as the distance M of each Hall sensor is reduced, the spatial resolution is increased.

In the inclusion inspection device according to the present invention, as shown in FIG. 4, by arranging two magnetic sensors in parallel and amplifying the differential values of the output signals, the dV _H / dX distribution of Equation 7 can be obtained. According to the present invention, when the intensity of the external magnetic field is significantly greater than the leakage magnetic flux due to the presence of defects or inclusions by using a large magnetizer, the strength of the external magnetic field can be detected before the amplification can be detected. There is an effect that can reduce the effect on.

5 is a diagram illustrating a data processing unit.

Referring to FIG. 5, the data processor 40 includes an amplifier 41 including a filter 41, an analog to dogital (AD) converter 43, and an operation processor 44.

The amplifier 41 amplifies the differential values of the first output signal and the second output signal described above, and the filter 41 filters the differential values of the first output signal and the second output signal. do. Filtering and amplification can be reversed.

The AD converter 43 converts the output signal of the amplifier 41 into a digital signal.

On the other hand, the calculation processing section 44 quantitatively quantifies the intensity distribution of the leaked magnetic flux leaking from the cold rolled steel sheet based on the output signal of the AD converter 43, and outputs the digitized data as an image. Further, the calculation processing section 44 calculates the derivative value of the differential values of the first and second output signals generated at each position of the cold rolled steel sheet, digitizes the calculated derivative value, and outputs the digitized data as an image. Can be. The data processing unit 40 may finally detect the presence of inclusions containing defects in the cold rolled steel sheet by analyzing the digitized data.

6A to 6D illustrate angles and scan directions formed between the magnetic sensor array and the magnetization direction.

FIG. 6A illustrates a case in which the cold rolled steel sheet is scanned in a direction parallel to the magnetization direction while the arrangement direction of the magnetic sensor array 30 is perpendicular to the scan direction, and FIG. 6B illustrates the arrangement of the magnetic sensor array 30. The cold rolled steel sheet is scanned in a direction parallel to the magnetization direction while the direction is at a specific angle with the scan direction, and FIG. 6C illustrates a state in which the arrangement direction of the magnetic sensor array 30 is perpendicular to the scan direction. A case of scanning in a direction perpendicular to the magnetization direction is illustrated, and FIG. 6D illustrates a case of scanning in a direction perpendicular to the magnetization direction in a state where the arrangement direction of the magnetic sensor array 30 forms a specific angle with the scan direction. .

6A to 6D, the arrow 35 indicates the arrangement direction of the magnetic sensor array 30, and the arrow 36 indicates the scan direction. For example, FIG. 6A shows that the magnetic sensor array 30 or the cold rolled steel sheet 20 is transported in parallel with the magnetization direction by the transfer unit.

The output of the differentially amplified magnetic sensor array 30 is stored by the AD converter 43 and used for imaging and analysis of the cold rolled steel sheet. On the other hand, a separate coordinate system xyz is introduced to distinguish it from the XYZ coordinate system. The Z-direction perpendicular to the plane of the cold rolled steel sheet is the same as the z-direction, but in the H-scan, V-scan, and G-scan, the respective scan directions are the x-direction. Thus, the x-direction in the H-scan means the X-direction, and the x-direction in the V-scan and G-scan means the Y-direction. Equation 4 can be modified as follows.

According to the present invention, since the output signal itself of the magnetic sensor array 30 means dV / dx, it is possible to efficiently extract only the information of the leakage magnetic flux due to the presence of inclusions or defects. In addition, by differentiating the output signal of the magnetic sensor array 30 again in the scan direction, it is possible to reduce the error of the bias voltage between the sensors, which is expressed as d ² V _H / dx ² as shown in the following equation.

In the present invention, when the magnetic sensor array 30 is tilted to form a specific angle with the scan direction and GH-scan, the spatial resolution is improved because it depends on the distance between the sensors, but the measurement area is narrower.

On the other hand, the calculation processing unit 44 of the data processing unit 40 may integrate the pixels of the d ² V _H / dx ² image, which is a derivative value, into a predetermined area as shown in Equation 13 below.

Equation (13) has the effect of a low pass filter such as a moving average, and can implement a noise canceling effect in software. As a result, only information about inclusions can be extracted.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Accordingly, the scope of protection of the present invention should be construed in accordance with the following claims, and all technical ideas within the scope of equivalents and equivalents thereof should be construed as being covered by the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 illustrates an apparatus for flaw detection of inclusions in a cold rolled steel sheet according to an embodiment of the present invention.

2 (a) and 2 (b) each illustrate an apparatus for flaw detection of inclusions in a cold rolled steel sheet according to an embodiment of the present invention.

3 (a) to 3 (f) are diagrams for explaining the principle of flaw detection of inclusions by leak magnetic flux detection, respectively.

4 illustrates a magnetic sensor array in accordance with the present invention.

5 is a diagram illustrating a data processing unit.

6a to 6d are views illustrating angles and scan directions formed between the magnetic sensor array and the magnetization direction;

Claims (8)

An inclusion inspection device for continuously inspecting inclusions in a rolled cold rolled steel sheet, A magnetization unit generating a magnetic field having a magnetization direction in one direction by using a DC current, and magnetizing a region to be measured of the cold rolled steel sheet using the generated magnetic field; A first magnetic sensor array including n magnetic sensors spaced in a row at regular intervals, the first magnetic sensor array generating a first output signal corresponding to a leaked magnetic flux leaking from the magnetized measured region; A second output signal including n magnetic sensors spaced apart in a row at the same interval as the magnetic sensors of the first magnetic sensor array, and generating a second output signal corresponding to the leakage magnetic flux leaking from the magnetized measured region; A second magnetic sensor array spaced apart from and parallel to the first magnetic sensor array; A transfer unit configured to transfer the magnetization unit or the first and second magnetic sensor arrays in a direction parallel to the magnetization direction of the magnetization unit so that the first and second magnetic sensor arrays scan the leakage magnetic flux of the cold rolled steel sheet; And A data processor configured to receive the differential values of the first and second output signals and to quantify the intensity distribution of the leakage magnetic flux leaking from the magnetized measurement region; The first and second magnetic sensor arrays are arranged such that an array direction is inclined with the magnetization direction of the magnetization part, and is connected to transfer the differential values of the first and second output signals to the data processor. Inclusion flaw detection apparatus of cold rolled steel sheet to do. The method of claim 1, In the first and second magnetic sensor array, the first power terminal of each magnetic sensor is connected to a first power line, In the first and second magnetic sensor array, the second power terminal of each magnetic sensor is connected to a ground line, The first output terminal of each magnetic sensor in the first magnetic sensor array is connected to the data processor, The first output terminal of each magnetic sensor in the second magnetic sensor array is connected to the data processor, And a second output terminal of each of the magnetic sensors of the first magnetic sensor array is connected to a second output terminal of the magnetic sensors of the second magnetic sensor array positioned in the same row, respectively. The method of claim 1, wherein the data processing unit An amplifier for filtering and amplifying differential values of the first and second output signals; An analog to dogital (AD) converter for converting the output signal of the amplifier into a digital signal; And And an arithmetic processing unit which quantitatively quantifies the intensity distribution of the leakage magnetic flux leaking from the cold rolled steel sheet based on the output signal of the AD converter, and outputs the digitized data as an image. . The method of claim 3, wherein the operation processing unit The differential detection value of the differential value of the said 1st and 2nd output signal generate | occur | produced in each position of the said cold rolled steel sheet, Computing the derivative value of the cold rolled steel sheet, It characterized by the above-mentioned. An inclusion inspection device for continuously inspecting inclusions in a rolled cold rolled steel sheet, A magnetization unit generating a magnetic field having a magnetization direction in one direction by using a DC current, and magnetizing a region to be measured of the cold rolled steel sheet using the generated magnetic field; A first magnetic sensor array including n magnetic sensors spaced in a row at regular intervals, the first magnetic sensor array generating a first output signal corresponding to a leaked magnetic flux leaking from the magnetized measured region; A second output signal including n magnetic sensors spaced apart in a row at the same interval as the magnetic sensors of the first magnetic sensor array, and generating a second output signal corresponding to the leakage magnetic flux leaking from the magnetized measured region; A second magnetic sensor array spaced apart from and parallel to the first magnetic sensor array; A transfer unit configured to transfer the magnetization unit or the first and second magnetic sensor arrays in a direction perpendicular to the magnetization direction of the magnetization unit so that the first and second magnetic sensor arrays scan the leakage magnetic flux of the cold rolled steel sheet; And A data processor configured to receive the differential values of the first and second output signals and to quantify the intensity distribution of the leakage magnetic flux leaking from the magnetized measurement region; The first and second magnetic sensor arrays are arranged such that an array direction is inclined with the magnetization direction of the magnetization part, and is connected to transfer the differential values of the first and second output signals to the data processor. Inclusion flaw detection apparatus of cold rolled steel sheet to do. The method of claim 5, In the first and second magnetic sensor array, the first power terminal of each magnetic sensor is connected to a first power line, In the first and second magnetic sensor array, the second power terminal of each magnetic sensor is connected to a ground line, The first output terminal of each magnetic sensor in the first magnetic sensor array is connected to the data processor, The first output terminal of each magnetic sensor in the second magnetic sensor array is connected to the data processor, And a second output terminal of each of the magnetic sensors of the first magnetic sensor array is connected to a second output terminal of the magnetic sensors of the second magnetic sensor array positioned in the same row, respectively. The method of claim 5, wherein the data processing unit An amplifier for filtering and amplifying differential values of the first and second output signals; An analog to dogital (AD) converter for converting the output signal of the amplifier into a digital signal; And And an arithmetic processing unit which quantitatively quantifies the intensity distribution of the leakage magnetic flux leaking from the cold rolled steel sheet based on the output signal of the AD converter, and outputs the digitized data as an image. . The method of claim 7, wherein the operation processing unit The differential detection value of the differential value of the said 1st and 2nd output signal generate | occur | produced in each position of the said cold rolled steel sheet, Computing the derivative value of the cold rolled steel sheet, It characterized by the above-mentioned.

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