KR101441750B1 - Apparatus for detecting magnetic flex leakage - Google Patents

Abstract

One embodiment of the leakage flux detecting apparatus according to the present invention includes: a sensing unit for passing a magnetic flux generated in a plurality of directions through a steel material to sense a leakage magnetic flux generated in the steel material; A lift-off control unit for allowing the sensing unit to pass the magnetic flux through the steel and move the sensing unit such that a gap between the sensing unit and the steel is maintained so as to sense leakage flux of the steel; And a defect detection unit for detecting whether or not the steel is defective by using a change amount of the leakage magnetic flux,
According to the present invention, it is possible to easily detect the defects formed in various directions in the steel material, thereby improving the reliability of the leakage flux detecting device.

Description

[0001] Apparatus for detecting magnetic flux leakage [0002]

The present invention relates to a device for detecting leakage magnetic flux.

Local defects in steel are not a problem of steel parts, but they reduce the durability of the entire structure. Therefore, various inspection methods have been proposed to improve the quality and safety of steel products by detecting defects of steel products in advance.

Non-destructive methods to detect these local defects include visual inspection (VT), penetration test (PT), ultrasound inspection (UT), radiographic examination (RT), eddy current testing (ECT) . However, there is a disadvantage in that the visual inspection and the ultrasonic inspection depend on the experience and subjectivity of the inspector, and the reliability and reproducibility are low. The radiographic inspection has a disadvantage in that it is difficult to perform inspection for a linear defect such as a crack perpendicular to the test surface, The defect inspection method has a disadvantage in that it can only detect defects near the surface or the surface of the conductor material.

On the other hand, a magnetic flux leakage (MFL) measurement method for measuring a magnetic flux leaked due to defects in the inner and outer walls of a test subject can be used only in a structure composed of a ferromagnetic material, It is widely used because it can detect an internal defect.

FIG. 1 is a view showing a principle of detecting defects made of steel using a leakage flux detecting device according to the related art. FIG. 2 shows a problem in detecting defects of steel using a leakage flux detecting device according to the related art Fig.

As can be seen from FIG. 1, the leakage flux detecting device 10 according to the prior art detects a defect 55 inside the steel material 50 by using the yoke 20.

When the steel member 50 is magnetized by using the magnetic force lines generated in the yoke 20, magnetoresistance occurs in a portion where the defect 55 exists. The lines of magnetic force that bypass the defects 55 in accordance with the magnetoresistance converge around the defects 55 and increase the intensity of the magnetic field around the defects 55. That is, as shown in FIG. 1, the lines of magnetic force passing through the steel material 50 cause deformation around the defects 55, so that the defects 55 in the steel material 50 can be measured by measuring the deformation of the lines of magnetic force .

However, as shown in FIG. 2, when the defects 55 are formed in a direction parallel to the lines of magnetic force, there is a problem that it is difficult to detect the defects 55 because the deformation of the lines of magnetic force is not large.

In the leakage flux detecting device 10 according to the related art, when vibration or the like occurs in the steel material 50 moving along the steel production line, the distance between the yoke 20 and the steel material 50 is irregular There is a problem that it is difficult to accurately detect the defects 55 because a lift-off occurs in which the magnetic force lines vary irregularly.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is a technical object of the present invention to provide a leakage flux detecting device capable of easily detecting defects formed in various directions.

It is another object of the present invention to provide a leakage flux detecting apparatus capable of accurately detecting defects by reducing the influence of a lift-off in a steel product.

According to an aspect of the present invention, there is provided an apparatus for detecting leakage flux, comprising: a sensing unit for passing a magnetic flux generated in a plurality of directions through a steel to sense a leakage magnetic flux generated in the steel; A lift-off control unit for allowing the sensing unit to pass the magnetic flux through the steel and move the sensing unit such that a gap between the sensing unit and the steel is maintained so as to sense leakage flux of the steel; And a defect detection unit for detecting the defect of the steel using the change amount of the leakage magnetic flux.

According to an aspect of the present invention, there is provided a leakage flux detecting apparatus including: a first yoke generating a first magnetic flux in a first direction; A second yoke generating a second magnetic flux in a second direction different from the first direction; A sensor control unit alternately generating the first magnetic flux and the second magnetic flux such that the first magnetic flux and the second magnetic flux do not interfere with each other; And a defect detection unit for detecting a defect of the steel using a change amount of a leakage magnetic flux generated as the first magnetic flux and the second magnetic flux pass through the steel.

According to the present invention, it is possible to improve the reliability of the leakage flux detecting device by generating a magnetic flux in a plurality of directions to easily detect defects formed in various directions inside the steel.

In addition, according to the present invention, it is possible to detect defects formed inside the steel material without being greatly influenced by lift-off occurring during transportation of the steel material, thereby improving the reliability of the leakage flux detecting device.

In addition, according to the present invention, there is an effect that the position of a defect formed in the steel material is three-dimensionally detected, thereby improving the accuracy of the leakage flux detecting apparatus.

1 is a view showing a principle of detecting defects made of steel using a leakage flux detecting apparatus according to the prior art.
FIG. 2 is a view showing a problem in detecting a defect of a steel material by using a leakage flux detecting device according to the related art.
3 is a view showing an embodiment of a leakage flux detecting apparatus according to the present invention.
4 is a block diagram showing an embodiment of a leakage flux detecting apparatus according to the present invention.
5 is a view showing an embodiment of a sensing unit of a leakage flux detecting apparatus according to the present invention.
6 is a view showing another embodiment of the sensing unit of the leakage flux detecting apparatus according to the present invention.
FIGS. 7 to 9 are diagrams for detecting defects made of steel using the leakage flux detecting apparatus according to the present invention. FIG.
10 is a view showing an embodiment of a shielding portion of a leakage flux detecting device according to the present invention.
11 is a flowchart showing an embodiment of a leakage flux detecting method according to the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is a view showing an embodiment of a leakage flux detecting apparatus according to the present invention, and FIG. 4 is a block diagram showing an embodiment of a leakage flux detecting apparatus according to the present invention.

3 and 4, the leakage flux detecting apparatus 100 according to the present invention includes a sensing unit 200, and in one embodiment, includes a lift-off control unit 300 and a defect detection unit 400, As shown in FIG.

The sensing unit 200 passes the magnetic flux generated in a plurality of directions through the steel material 510 to measure the leakage flux reflected from the steel material 510. The sensing unit 200 includes a magnetic flux generating unit 210 including at least one yoke 211 and 213 for generating a magnetic flux in a plurality of directions and a probe unit 200 for measuring a magnetic flux leaking from the magnetic flux passing through the steel member 510. [ (230). In one embodiment, the sensing unit 200 may further include at least one of a sensor control unit 220, a shielding unit 240, and a sensor driving unit 250.

5 is a view showing an embodiment of a sensing unit of a leakage flux detecting apparatus according to the present invention.

4 and 5, in one embodiment, the sensing unit 200 included in the leakage flux detecting apparatus 100 includes a first yoke 211, a second yoke 213, a sensor controller 220 ), And a probe unit 230.

The first yoke 211 generates a first magnetic flux in a first direction. The first magnetic flux generated at one end of the first yoke 211 converges to the other end of the first yoke 211, and the first magnetic flux passes through the adjacent steel member 510.

The second yoke 213 generates a second magnetic flux in a second direction different from the first direction. The second magnetic flux generated at one end of the second yoke 213 converges to the other end of the second yoke 213, and the second magnetic flux passes through the adjacent steel member 510. In one embodiment, the second yoke 213 may be formed to be orthogonal to the first yoke 211, in which case the first magnetic flux and the second magnetic flux are orthogonal to each other.

5, the magnetic flux generating unit 210 of the sensing unit 200 includes the first yoke 211 and the second yoke 213. However, the magnetic flux generating unit 210 of the sensing unit 200 may include the first yoke 211 and the second yoke 213, The included yoke is not necessarily limited to only two, but may further include a further yoke. For example, the sensing unit 200 may include three yokes, in which case each yoke may be formed to have an angle of 60 degrees.

In one embodiment, the first yoke 211 and the second yoke 213 may be electromagnets. Thus, the first yoke 211 may include a first electromagnet to generate a first magnetic flux, and the second yoke 213 may include a second electromagnet to generate a second magnetic flux.

The sensor control unit 220 alternately operates the first yoke 211 and the second yoke 213. When the first magnetic flux and the second magnetic flux generated from the first yoke 211 and the second yoke 213 simultaneously pass through the steel material, the first magnetic flux and the second magnetic flux interfere with each other, When the first yoke 211 generates the first magnetic flux, the second yoke 213 prevents the second yoke 213 from generating the second magnetic flux. When the second yoke 213 generates the second magnetic flux, To prevent the first magnetic flux from being generated.

The first yoke 211 and the second yoke 213 may be electromagnets so that the sensor control unit 220 controls the electric power supplied to the first yoke 211 and the second yoke 213 So that the first magnetic flux and the second magnetic flux are alternately generated.

The probe 230 measures a first leakage magnetic flux leaked from the first magnetic flux and a second leakage magnetic flux leaked from the second magnetic flux. In one embodiment, the probe 230 may be formed at the center of the first yoke 211 and the second yoke 213.

Further, in one embodiment, the probe unit 230 may include a three-dimensional magnetic sensor capable of measuring magnetic flux in three dimensions of X, Y, and Z axes.

 6 is a view showing another embodiment of the sensing unit of the leakage flux detecting apparatus according to the present invention.

4 and 6, in one embodiment, the sensing unit 200 included in the leakage flux detecting apparatus 100 includes a first yoke 211, a sensor driving unit 250, and a probe 230 ).

The first yoke 211 generates a magnetic flux, and may be an electromagnet or a permanent magnet. The first yoke 211 is rotatable in a direction parallel to the steel, so that the magnetic flux generated in the first yoke 211 can be incident on the steel in various directions.

The sensor driving unit 250 is connected to the first yoke 211 to rotate the first yoke 211 in a direction parallel to the steel product. The sensor driving unit 250 rotates the first yoke 211 on the steel so that the magnetic flux generated from the first yoke 211 can be incident on the steel in various directions.

The probe 230 measures leakage magnetic fluxes generated in a plurality of directions as the first yoke 211 rotates. When the first yoke 211 rotates by the sensor driving unit 250, the magnetic flux generated in the first yoke 211 is incident on the steel in a plurality of directions. Accordingly, the magnetic fluxes are reflected in a plurality of directions of the magnetic flux leaking by the magnetic fluxes incident in a plurality of directions. The probe 230 measures the leakage magnetic fluxes in the plurality of directions. In one embodiment, the probe 230 can measure the leakage magnetic flux every time the first yoke 211 rotates by 90 degrees. However, the present invention is not limited thereto, and when the first yoke 211 rotates 60 degrees The leakage magnetic flux may be measured every time the rotor is rotated at a rotation angle smaller than the rotation angle.

Further, in one embodiment, the probe unit 230 may include a three-dimensional magnetic sensor capable of measuring magnetic flux in three dimensions of X, Y, and Z axes. In this case, the X axis may be a first axis parallel to the traveling direction of the steel, the Y axis may be a second axis perpendicular to the traveling direction, and the Z axis may be perpendicular to the first axis and the second axis Can be the third axis.

5 and 6 illustrate a structure for generating a magnetic flux in a plurality of directions in the leakage flux detecting apparatus 100 according to the present invention.

Hereinafter, a method of measuring defects made of steel by analyzing leaked magnetic flux leaked from a magnetic flux formed in a plurality of directions will be described with reference to FIGS. 7 to 9. FIG.

FIGS. 7 to 9 are diagrams for detecting defects made of steel using the leakage flux detecting apparatus according to the present invention. FIG.

7, the first yoke 211 is aligned in the X-axis direction on the steel member 510, and the first magnetic flux generated in the first yoke 211 extends in the X- .

8, the second yoke 213 is aligned in the Y-axis direction at an angle of 90 degrees with respect to the first yoke 211 on the steel member 510, and is generated in the second yoke 213 And the second magnetic flux passes through the steel material 510 in the Y-axis direction.

At this time, the defect 600 is formed to extend in the X-axis direction. It can be seen that the direction of the first magnetic flux is parallel to the direction of the defect 600, and the amount of change of the first leakage magnetic flux is not large. Therefore, it is difficult to precisely measure the presence or the size of the defect 600 by simply measuring the first leakage magnetic flux.

However, since the direction of the second magnetic flux is perpendicular to the direction of the defect 600, it can be seen that the amount of change in the second leakage magnetic flux is larger than the amount of change in the first leakage magnetic flux. Therefore, the defect 600, which is difficult to detect by only the first leakage magnetic flux, can be easily detected by analyzing the first leakage magnetic flux and the second leakage magnetic flux together.

On the other hand, the first magnetic flux and the second magnetic flux pass through the inside of the steel in the Z-axis direction. 9, the first magnetic flux generated in the first yoke 211 passes through the inner portion of the steel in the Z-axis direction, and the first magnetic flux generated by the steel inner defect 600 It can be seen that the path of the magnetic force lines is changed and a leakage magnetic flux is generated. Therefore, by analyzing such leaked magnetic flux, the depth (Z-axis direction) of the defect 600 can be measured.

As described above, the leakage flux detecting apparatus 100 according to the present invention generates a magnetic flux in a plurality of directions and measures it with a probe 230 including a three-dimensional magnetic sensor, thereby easily detecting a defect in the steel .

10 is a view showing an embodiment of a shielding portion of a leakage flux detecting device according to the present invention.

10, the sensing unit 200 may further include a shielding part 240. As shown in FIG. The shield 240 shields the magnetic flux generating part 210 generating magnetic flux in a plurality of directions and the probe 230 measuring the leakage magnetic flux with the external magnetic field of the sensing unit 200.

In one embodiment, the shield 240 may be formed in the form of an outer case that covers the magnetic flux generating portion 210 and the probe portion 230, and may be formed of a material capable of shielding the magnetic field.

At this time, the shielding part 240 forms a predetermined open area in the area corresponding to the magnetic flux generating part 210 and the probe part 230 on the side facing the steel, so that the magnetic flux of the magnetic flux generating part 210 So that a leak magnetic flux can be applied to the probe unit 230.

Referring again to FIGS. 3 and 4, the lift-off control unit 300 controls the sensing unit 200 such that the distance between the sensing unit 200 and the steel stock 510 is kept constant.

To this end, the lift-off control unit 300 includes a distance sensing unit 310, a drive control unit 320, and a drive motor unit 330.

The distance sensing unit 310 measures a distance D between the sensing unit 200 and the steel material 510. In one embodiment, the distance sensing unit 310 may be formed at one end of the sensing unit 200, and the distance measured using a plurality of sensors may be averaged.

The drive control unit 320 receives the distance measured by the distance sensing unit 310 and compares the distance measured by the sensing unit 200 and the steel 510 to determine a moving direction and a moving distance of the sensing unit 200 .

The distance between the sensing unit 200 and the steel material 510 must be constant in order to measure the defects of the steel material 510 by measuring the leakage magnetic flux by the sensing unit 200. However, the steel material 510 can move up and down while the steel material 510 moves along the moving roller. When the distance between the sensing unit 200 and the steel material 510 changes according to the movement, a lift-off effect in which noise is generated due to a change in magnetic coupling may occur.

The drive control unit 320 controls the distance between the sensing unit 200 and the steel material 510 to be constant so that the sensing unit 200 can accurately measure the leakage magnetic flux according to the defect of the steel material 510 do.

The driving motor unit 330 is connected to one end of the sensing unit 200 and moves the sensing unit 200 in the vertical direction to the sensing unit 200 according to a command of the driving control unit 320, The distance D between the steel members 510 is kept constant.

The defect detection unit 400 includes a defect detection unit 410, a defect analysis unit 420, and a defect display unit 430.

The defect detecting unit 410 analyzes the leakage magnetic flux measured by the sensing unit 200 and detects whether the steel material 510 is defective or not. That is, the defect detector 410 comprehensively analyzes the leakage flux measured in a plurality of directions to determine whether or not there is a defect in the steel material 510.

The defect analyzer 420 analyzes the three-dimensional coordinates of defects of the steel material 510 detected by the defect detector 410. The defect analyzing unit 420 analyzes the positions of the defects detected by the defect detecting unit 410 in three-dimensional coordinates, and analyzes the size and direction of the defects.

The defect display unit 430 displays the position of the defect in three dimensions by mapping the three-dimensional coordinates of the defect to the steel material. The defect display unit 430 maps the position, size, and direction of defects analyzed by the defect analysis unit 420 to the coordinates on the steel stocker 510 and displays it three-dimensionally.

<Leakage magnetic flux detection method>

11 is a flowchart showing an embodiment of a leakage flux detecting method according to the present invention.

As shown in FIG. 11, first, the sensing unit is controlled so that the distance between the sensing unit and the moving steel is a preset distance (S1100).

In order to detect defects made of steel by measuring the leakage magnetic fluxes that are reflected when the magnetic flux generated in the sensing unit passes through the steel material, the distance between the sensing unit and the steel material is made constant, It is important to reduce the lift-off effect, which is the noise that is caused by the noise.

However, as the steel material moves along the moving roller, the steel material can move in the up and down direction, and this movement changes the distance between the sensing unit and the steel to create a lift-off effect. This lift-off effect acts as a noise on the reflected leakage flux, which leads to inaccurate fault detection.

Therefore, the drive control unit controls the distance between the sensing unit and the steel to be constant, so that the sensing unit can measure the leakage magnetic flux corresponding to the defect of the steel while maintaining a constant separation distance.

Next, the first magnetic flux generated in the first direction is passed through the steel material and the first leakage magnetic flux reflected from the steel material is measured (S1200). The first magnetic flux generated in the magnetic flux generating portion passes through the steel material. At this time, if there is a defect in the steel material, a change in the magnetic force lines occurs and a first leakage magnetic flux is generated. The probe measures the first leakage flux.

Next, the sensing unit is controlled so that the distance between the sensing unit and the steel material maintains the separation distance (S1300).

To this end, the distance sensing unit continuously measures the distance between the sensing unit and the steel, and outputs the distance to the driving control unit. When the distance to the driving control unit is increased, the sensing unit is lowered through the driving motor unit, The position of the sensing unit is raised through the driving motor unit.

Although it has been described that the step of controlling the sensing unit (S1300) is executed between the step of measuring the first leakage magnetic flux and the step of measuring the second leakage magnetic flux, the measurement distance between the sensing unit and the steel The distance adjusting step of bringing the sensing unit closer to the steel material if the distance is larger than the spacing distance and spacing the sensing unit from the steel material when the measurement distance is smaller than the spacing distance, It can be executed at any time during the measurement.

Next, the second magnetic flux generated in the second direction is passed through the steel and the second leakage flux reflected from the steel is measured (S1400). The second magnetic flux generated in the magnetic flux generating portion passes through the steel material. At this time, when there is a defect in the steel material, a change in the magnetic force lines occurs and a second leakage magnetic flux is generated. The probe measures the second leakage flux.

The first magnetic flux and the second magnetic flux are generated in different directions and applied to the steel material, in one embodiment, the first magnetic flux and the second magnetic flux may be orthogonal.

Hereinafter, a method of generating the first magnetic flux and the second magnetic flux in different directions will be described by taking the first and second embodiments as an example.

In the first embodiment, the first magnetic flux and the second magnetic flux can be generated by alternately applying a current to the first yoke and the second yoke that are orthogonal to each other. That is, the magnetic flux generating portion includes a first yoke and a second yoke formed in an orthogonal direction, generates a first magnetic flux in the first yoke, and generates a second magnetic flux in the second yoke.

In this case, the measuring of the first leakage magnetic flux may include generating a first magnetic flux by applying a current to the first yoke formed in the first direction, and generating the first magnetic flux by applying a first Measure leakage magnetic flux. The step of measuring the second leakage magnetic flux may include the steps of interrupting a current applied to the first yoke to prevent a first magnetic flux from being generated and applying a current to the second yoke formed in the second direction, Generates a magnetic flux, and measures a second leakage magnetic flux which is reflected when the second magnetic flux is applied to the steel material.

This process is repeated to control the first magnetic flux and the second magnetic flux so as not to interfere with each other and to measure the first leakage magnetic flux and the second leakage magnetic flux which are reflected when each of the first magnetic flux and the second magnetic flux is applied to the steel material .

In the second embodiment, the first magnetic flux and the second magnetic flux can be generated by rotating one yoke in a direction parallel to the steel product. That is, the magnetic flux generating portion includes one yoke, and the yoke is formed so as to be rotatable in a direction parallel to the steel material on the steel material. When the yoke is rotated by the sensor driving unit, a magnetic flux is generated in a plurality of directions, and thus the eccentric rotation speed is returned in a plurality of directions.

Even if a magnetic flux continuously occurs in one yoke, if the yoke rotates in a direction parallel to the steel material, the direction of the magnetic flux is continuously changed. At this time, when the magnetic flux is measured at a constant rotation angle, The effect can be obtained.

In this case, the measuring of the second leakage magnetic flux may include rotating the magnetic flux generating unit in the second direction rotated by a predetermined angle in the first direction to generate the second magnetic flux, And measures the second leakage magnetic flux that is echoed when it is applied.

Next, the first leakage magnetic flux and the second leakage magnetic flux are analyzed to detect the defect of the steel, and the three-dimensional coordinates of the defect are analyzed (S1500). The first leakage magnetic flux and the second leakage magnetic flux according to the magnetic flux incident in different directions can more accurately detect defects in the steel, and when the leakage magnetic flux is measured by a three-dimensional magnetic sensor, the three- Can be measured more accurately.

The defect detection unit synthesizes the leakage magnetic fluxes measured by the three-dimensional magnetic sensor in a plurality of directions, analyzes the defects, analyzes the positions and sizes of defects in the steel, analyzes the defects, and displays the three- have.

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof.

It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

100 - Leakage flux detector 200 - Sensing unit
210 - magnetic flux generator 211 - first yoke
213 - second yoke 220 - sensor control unit
230 - Probe 240 - Shield
250 - Sensor driving unit 300 - Lift off control unit
310 - distance sensing unit 320 - drive control unit
330 - Drive motor unit 400 - Defect detection unit
410 - Defect detection unit 420 - Defect analysis unit
430 - defect indicator

Claims (14)

A sensing unit for alternately passing a magnetic flux generated in a plurality of directions through a steel material to sense a leakage magnetic flux generated in the steel material;
A lift-off control unit that moves the sensing unit such that a distance between the sensing unit and the steel material is kept constant so that the sensing unit passes the magnetic flux through the steel material and senses the leakage flux of the steel material; And
And a defect detection unit for detecting the defect of the steel using the change amount of the leakage magnetic flux. The method according to claim 1,
The sensing unit includes:
A first yoke generating a first magnetic flux in a first direction; And
And a second yoke generating a second magnetic flux in a second direction different from the first direction,
And the leakage magnetic flux of the steel is measured by alternately passing the first magnetic flux of the first yoke and the second magnetic flux of the second yoke through the steel material. The method according to claim 1,
The sensing unit includes:
And a sensor control unit for alternately generating the first magnetic flux and the second magnetic flux such that the first magnetic flux generated in the first direction and the second magnetic flux generated in the second direction are not interfered with each other. The method according to claim 1,
Wherein the sensing unit includes a first electromagnet for generating a first magnetic flux in a first direction and a second electromagnet for generating a second magnetic flux in a second direction perpendicular to the first direction, Device. The method according to claim 1,
The sensing unit includes:
A first yoke generating a magnetic flux; And
And a sensor driver for generating a first magnetic flux in a first direction and rotating the first yoke such that the first yoke generates a second magnetic flux in a second direction different from the first direction,
And the leakage magnetic flux of the steel is measured by alternately passing the first magnetic flux and the second magnetic flux through the steel material. The method according to claim 1,
The sensing unit includes:
The leakage flux is measured in a first axis in a direction parallel to a traveling direction of the steel, a second axis in a direction perpendicular to the traveling direction, and a third axis direction perpendicular to the first and second axes And a probe for measuring the leakage magnetic flux in three dimensions. The method according to claim 1,
The sensing unit includes:
And a shielding portion for shielding a probe for measuring the leakage magnetic flux with an external magnetic field of the sensing unit. The method according to claim 1,
The lift-off control unit includes:
A distance sensing unit for measuring a distance between the sensing unit and the steel product; And
And a drive control unit for controlling the movement direction and the movement distance of the sensing unit so that the measured distance is kept constant. The method according to claim 1,
Wherein the defect detection unit detects the defect of the steel using the first leaked flux sensed in the first direction and the second leaked flux sensed in the second direction. The method according to claim 1,
Wherein the defect detection unit derives a three-dimensional coordinate at which the defect of steel is located, maps the three-dimensional coordinates of the defect to the steel, and displays the position of the defect in three dimensions, Device. A first yoke generating a first magnetic flux in a first direction;
A second yoke generating a second magnetic flux in a second direction different from the first direction;
A sensor control unit alternately generating the first magnetic flux and the second magnetic flux such that the first magnetic flux and the second magnetic flux do not interfere with each other; And
And a defect detection unit for detecting a defect of the steel using a change amount of a leakage magnetic flux generated as the first magnetic flux and the second magnetic flux pass through the steel material. 12. The method of claim 11,
And moving the first yoke and the second yoke such that a gap between the first yoke and the steel and a gap between the second yoke and the steel are maintained at a previously set separation distance, Further comprising a lift-off control unit for maintaining a predetermined distance from the steel material and allowing the steel material to pass therethrough. 12. The method of claim 11,
Further comprising: a probe for measuring the leakage magnetic flux; and a lift-off control unit for moving the probe so that the interval between the steels is maintained at a predetermined separation distance. 12. The method of claim 11,
A first leakage magnetic flux generated as the first magnetic flux passes through the steel and a second leakage magnetic flux generated as the second magnetic flux orthogonal to the first magnetic flux pass through the steel is detected in three dimensions Further comprising a probe unit for detecting the leakage flux.

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