A magnetic flux leakage detection probe device, a magnetic flux leakage detection probe device and a magnetic flux leakage detection method

Abstract

The application discloses a magnetic flux leakage detection probe device, a weak magnetic device and a detection method. The magnetic flux leakage detection probe device is used for detecting the metal surface of the bottom plate of a large oil storage tank. The detection device (2) for detecting the metal piece (1) is connected with a magnetic flux leakage detector (3). The detection device (2) is generally composed of a magnetization device (21) of a U-shaped strong magnet and a magnetic flux leakage detection sensor (22) arranged at the center of the U-shaped magnet port of the magnetization device (21). The weak magnetic device (4) is used for weakening the magnetic force of the U-shaped permanent magnet of the magnetization device during the detection process of the magnetic flux leakage detection device. The lifting wheel device arranged on the shell of the detection device is used for separating the strong magnet from the metal surface and pulling up the strong magnet of the detection device, so that the magnetic flux leakage detection device can be easily taken off from the metal surface or moved on the concave-convex surface, and the simple and labor-saving operation mode is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nondestructive testing, in particular to an electromagnetic testing and evaluation method for large metal devices, and more particularly to a magnetic flux leakage testing probe device, a magnetic flux weakening device and a testing method thereof. BACKGROUND

[0002] Conventional magnetic flux leakage testing probe devices, such as those used for testing the metal surface of the bottom plate of a large oil tank, are shown in the attached drawings. Figure 1 A testing device (2) for magnetic flux leakage testing of a metal piece (1) is connected to a magnetic flux leakage testing instrument (3). The testing device (2) generally comprises a magnetizing device (21) composed of a U-shaped strong magnet and a magnetic flux leakage testing sensor (22) arranged at the center of the U-shaped magnet port of the magnetizing device (21). The magnetic flux leakage testing sensor is generally a Hall sensor.

[0003] However, due to the strong magnetic attraction of the permanent magnet of the magnetizing device, it is very difficult to remove the testing probe device from the surface of the metal piece when testing is required. In addition, it is also very difficult to move the testing probe device when the surface of the metal piece has unevenness such as welds, and it is often difficult for an individual to operate, which causes great inconvenience to the testing personnel.

[0004] To overcome the above-mentioned problems, the present application adopts the following technical solutions. SUMMARY

[0005] The present application provides a magnetic flux leakage testing probe device, a magnetic flux weakening device and a testing method thereof. The technical solutions are as follows:

[0006] A magnetic flux weakening device for a magnetic flux leakage testing probe is used in a magnetic flux leakage testing device for testing the metal surface of the bottom plate of a large oil tank. The testing device (2) for magnetic flux leakage testing of a metal piece (1) is connected to a magnetic flux leakage testing instrument (3). The testing device (2) generally comprises a magnetizing device (21) composed of a U-shaped strong magnet and a magnetic flux leakage testing sensor (22) arranged at the center of the U-shaped magnet port of the magnetizing device (21). The magnetic flux leakage testing sensor is generally a Hall sensor. The magnetic flux weakening device (4) is used to weaken the magnetic force of the U-shaped permanent magnet of the magnetizing device during the testing process of the magnetic flux leakage testing device. The device is characterized by comprising a first magnetic yoke (41a) connected to the N-pole port (211) of the U-shaped strong magnet of the magnetizing device (21), a second magnetic yoke (41b) connected to the S-pole port (212) of the U-shaped strong magnet of the magnetizing device (21), and a first excitation and demagnetization coil (42a) and a second excitation and demagnetization coil (42b) wound on the first magnetic yoke (41a) and the second magnetic yoke (41b), respectively. The first excitation and demagnetization coil (42a) and the second excitation and demagnetization coil (42b) are connected to a direct current power source P.

[0007] Wherein, the leakage magnetic flux detection probe applies direct current power to generate reverse magnetic field in the opposite direction of the magnetization device, that is, the magnetic field N-pole generated by the first excitation demagnetization coil (42a) connected to direct current power P is connected to the N-pole port (211), and the magnetic field S-pole generated by the second excitation demagnetization coil (42b) connected to direct current power P is connected to the S-pole port (212). That is, in the case of necessity, the leakage magnetic flux detection probe device needs to be removed from the surface of the metal part, or when moving on the uneven regular metal surface such as a weld, the first excitation demagnetization coil (42a) and the second excitation demagnetization coil (42b) are applied with direct current power, so that the direction of the magnetic field generated thereby is opposite to the polarity of the magnetization device, so as to weaken the magnetic property of the strong permanent magnet of the magnetization device.

[0008] Further, the first excitation demagnetization coil (42a) and the second excitation demagnetization coil (42b) are connected to the direct current power P through the first switch K1 and the second switch K2, respectively.

[0009] Further, the height H of the first magnetic yoke (41a) and the second magnetic yoke (41b) is any value between 3 and 20 mm. The optimal height value is 5 mm.

[0010] Further, in the normal detection process of the leakage magnetic flux detection probe, direct current power is applied to generate a forward magnetic field in the same direction as the magnetization device, that is, the magnetic field S-pole generated by the first excitation demagnetization coil (42a) connected to direct current power P is connected to the N-pole port (211), and the magnetic field N-pole generated by the second excitation demagnetization coil (42b) connected to direct current power P is connected to the S-pole port (212). The magnetic field in the same direction has the effect of strengthening the magnetization device

[0011] The application also discloses a leakage magnetic flux detection device for detecting the metal part (1) such as a large oil storage tank in the detection device (2) for leakage magnetic flux detection, the detection device is connected to the leakage magnetic flux detector (3), and comprises a shell (5), a magnetization device (21) composed of a U-shaped strong magnet, and a leakage magnetic flux detection sensor (22) arranged at the center of the U-shaped magnet port of the magnetization device (21), characterized in that the weak magnetic device (4) is further included.

[0012] Further, the wheel device (50) for supporting and moving the detection device is arranged on the shell, wherein the wheel device (50) comprises a front wheel device (51) and a rear wheel device (52), and the height of the wheel device (50) can be adjusted as necessary; the front wheel device (51) is provided with a first adjusting device, and the rear wheel device (52) is provided with a second adjusting device, which respectively adjusts the height of the front wheel device (51) and the rear wheel device (52), and the height of the front wheel device (51) and the rear wheel device (52) can also be adjusted simultaneously. That is, the structure of adjusting the height of the front wheel device and the rear wheel device respectively can be adjusted according to different moving planes, such as the lap joint type weld surface, the spliced type weld surface, etc., and the height of the front wheel or the rear wheel is adjusted in advance to adapt to the purpose of easy movement on different planes. For example, on the lap joint weld surface, because the weld surface is a lower stepped wave surface, the rear wheel device can be lifted in advance, which is more suitable for lifting the detection surface of the lower wave surface, and the front wheel is not too large, which can more easily escape from the magnetic force and move the magnetic flux leakage detection device easily. For example, on the spliced weld surface, because the weld surface is an upper wave surface, the front wheel device can be lifted in advance, which is more suitable for the magnetic force constraint of lifting the detection surface of the upper wave surface, and the lifting of the front wheel can reduce the resistance of the upper wave, so as to realize the easy movement of the magnetic flux leakage detection device.

[0013] Further, the adjusting device respectively comprises a motor (531), a turbine (532) and a worm (533), and the front wheel device (51) and the rear wheel device (52) of the wheel device (50) are respectively fixed on the transverse rod (534) arranged on the worm (533).

[0014] Further, the metal surface detection sensor arranged on the shell of the detection device is further arranged, the metal surface detection sensor is connected to the controller, and after the metal surface detection sensor detects the change of the metal plane, the controller receives the signal and controls the height adjustment of the wheel device. The controller can be provided with a detection instrument, or a separate controller is installed on the detection device shell or the detection trolley, and the detection control panel is provided with different height adjustment modes of the wheel device under different moving conditions. For example, when the detection device needs to be removed, the height of the front and rear wheels is adjusted simultaneously; when the upper wave surface moves, the height of the front wheel device is adjusted in advance; and when the lower wave surface moves, the height of the rear wheel device is adjusted in advance.

[0015] The application also discloses a magnetic flux leakage detection method for evaluating defects of a metal surface of a large oil storage tank bottom plate, using the magnetic flux leakage detection device.

[0016] b. When the metal surface detection sensor detects a different change in the detection surface, the corresponding concave-convex surface movement mode is started, the wheel device height is adjusted, that is, the weak magnetic coil is connected to the reverse DC power supply, and the adjustment mode is selected, that is, when the upper wave surface moves, the front wheel device height is adjusted first, and when the lower wave surface moves, the rear wheel device height is adjusted first;

[0017] c. When the detection device needs to be removed, the disengagement mode is started, that is, the weak magnetic device is started to connect the weak magnetic coil to the reverse DC power supply, and the front wheel device and the rear wheel device are lifted at the same time. Various modes can be started through a manually operated button or an automatic controller provided on the detection instrument. The coil provided in the magnetization device of the detection device forms a reverse magnetic field to reduce the adsorption force of the strong magnet on the detected metal part, and the lifting wheel device provided on the detection device shell can lift the detection device, so that the detection device can be separated from the detection surface or moved on the detection surface when necessary,

[0018] Further, the concave-convex surface movement mode in step b is set as follows: when the metal detection surface is a concave moving wave surface, the height of the rear wheel device is adjusted first, and then the height of the front wheel device is adjusted; when the metal detection surface is a convex moving wave surface, the height of the front wheel device is adjusted first, and then the height of the rear wheel device is adjusted; and when the detection device needs to be removed, the height of the front wheel device and the rear wheel device is adjusted at the same time. The sensor detects the change in the metal surface, and automatically starts the corresponding mode or manually selects the different modes, such as starting the upper wave detection surface movement mode, the lower wave detection surface movement mode or the disengagement detection surface mode. The corresponding upper wave detection surface movement mode is set to first lower the height of the front wheel device, the lower wave detection surface movement mode is set to first lower the height of the rear wheel device, and the disengagement detection surface mode is set to lower the height of the front wheel device and the rear wheel device at the same time.

[0019] According to the above technical scheme, the magnetic flux leakage detection method and the magnetic flux leakage detection device have the following beneficial effects: the weak magnetic device arranged at the two end portions of the U-shaped magnet in the magnetizing device can not only realize the first step of reducing the magnetic force, but also form a layer of separation between the U-shaped magnet end portion and the metal detection surface when the weak magnetic device is not connected to the direct current, so as to promote the rapid decay of the magnetic force of the magnetizing device on the detected metal part and reduce the magnetic force of the strong magnet of the detection device adsorbed on the detection metal surface; and the lifting wheel device arranged on the shell of the detection device can pull up the strong magnet of the detection device upward at the same time when the strong magnet and the metal surface form a separation layer, so that the magnetic flux leakage detection device can be easily taken off from the detection metal surface or moved on the concave-convex surface, and a simple and labor-saving operation mode is realized. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 A use state schematic diagram of the prior art magnetic flux leakage detection device;

[0021] Figure 2 A detection device schematic diagram of the best embodiment of the present application;

[0022] Figure 3 A weak magnetic device schematic diagram of the detection device of the best embodiment of the present application;

[0023] Figure 4 A weak magnetic device structure schematic diagram of the detection device of the best embodiment of the present application;

[0024] Figure 5 A weak magnetic device schematic diagram of the detection device of the best embodiment of the present application;

[0025] Figure 6 A detection device schematic diagram of the best embodiment of the present application with a wheel device;

[0026] Figure 7 A perspective schematic diagram of the detection device of the best embodiment of the present application with a wheel device

[0027] Figure 8 A wheel device schematic diagram of the best embodiment of the present application;

[0028] Figure 9 A height adjusting device schematic diagram of the wheel device of the best embodiment of the present application;

[0029] Figure 10 A lifting adjusting schematic diagram of the wheel device of the detection device of the best embodiment of the present application;

[0030] Figure 11 A moving schematic diagram of the wheel device of the detection device of the best embodiment of the present application on different weld surfaces;

[0031] Figure 12A schematic diagram of the movement of the wheel device of the detection device in different weld surfaces, which is the preferred embodiment of the present invention;

[0032] Figure 13 This is a schematic diagram of the detection device in use according to the preferred embodiment of the present invention;

[0033] Figure 14 This is a schematic diagram showing the usage state of the detection device according to the preferred embodiment of the present invention. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0035] like Figures 1 to 5 As shown, a magnetic weakening device for a magnetic flux leakage detection probe is used in a magnetic flux leakage detection device for detecting the metal surface of the bottom plate of a large oil storage tank. In a detection device 2 for detecting magnetic flux leakage of a metal part 1, the detection device is connected to a magnetic flux leakage detector 3. The detection device 2 generally consists of a magnetizing device 21 composed of a U-shaped strong magnet and a magnetic flux leakage detection sensor 22 set at the center of the U-shaped magnet port of the magnetizing device 21. The magnetic weakening device 4 is a structural device used to weaken the magnetic force of the U-shaped permanent magnet of the magnetizing device when necessary during the detection process of the magnetic flux leakage detection device. It includes a first magnetic yoke 41a at the N pole port 211 and a second magnetic yoke 41b at the S pole port 212, which are seamlessly connected to the U-shaped strong magnet of the magnetizing device 21, and a first excitation and demagnetization coil 42a and a second excitation and demagnetization coil 42b respectively wound on the first magnetic yoke 41a and the second magnetic yoke 41b. The first excitation and demagnetization coil 42a and the second excitation and demagnetization coil 42b are respectively connected to a DC power supply P.

[0036] like Figure 4 As shown, when necessary, the magnetic flux leakage detection probe applies a DC power supply that generates a reverse magnetic field opposite to that of the magnetizing device. Specifically, the N pole of the magnetic field generated by the first excitation / demagnetization coil 42a connected to the DC power supply P is connected to the N pole port 211, and the S pole of the magnetic field generated by the second excitation / demagnetization coil 42b connected to the DC power supply P is connected to the S pole port 212. In other words, when it is necessary to remove the magnetic flux leakage detection probe from the surface of the metal part being detected, or when it needs to be moved on an uneven or irregular metal surface such as a weld, a DC power supply is applied to the first excitation / demagnetization coil 42a and the second excitation / demagnetization coil 42b, so that the direction of their generated magnetic fields is opposite to the polarity of the magnetizing device, thereby weakening the strong magnetism of the permanent magnet in the magnetizing device.

[0037] like Figure 4 As shown, the first excitation and demagnetization coil 42a and the second excitation and demagnetization coil 42b are connected to the DC power supply P through the first switch K1 and the second switch K2 respectively.

[0038] like Figure 5As shown, the height H of the first yoke 41a and the second yoke 41b is any value between 3 and 20 mm. A preferred height value H is 5 mm.

[0039] like Figure 4 As shown, during normal detection, the magnetic flux leakage detection probe is powered by a DC power supply that generates a positive magnetic field in the same direction as the magnetizing device. Specifically, the S pole of the magnetic field generated by the first excitation / demagnetization coil 42a connected to the DC power supply P is connected to the N pole port 211, and the N pole of the magnetic field generated by the second excitation / demagnetization coil 42b connected to the DC power supply P is connected to the S pole port 212. This magnetic field in the same direction strengthens the magnetizing device.

[0040] like Figure 1 and Figure 6 , 7 As shown in the figure, the present invention also discloses a magnetic flux leakage detection device, which is used to detect magnetic flux leakage of metal parts 1 such as large oil storage tanks. The detection device is connected to the magnetic flux leakage detector 3 and includes a housing 5, a magnetization device 21 composed of U-shaped strong magnets, a magnetic flux leakage detection sensor 22 disposed at the center of the U-shaped magnet port of the magnetization device 21, and a weak magnetic device 4 disposed on the U-shaped magnet port of the magnetization device 21.

[0041] like Figure 6 , 7 As shown, it also includes a wheel assembly 50 disposed on the housing 5 for supporting and moving the detection device. The wheel assembly 50 includes a front wheel assembly 51 and a rear wheel assembly 52. ​​The wheel assembly 50 can be height-adjusted when necessary. The front wheel assembly 51 is provided with a first adjustment device, and the rear wheel assembly 52 is provided with a second adjustment device. The heights of the front wheel assembly 51 and the rear wheel assembly 52 can be adjusted respectively, or simultaneously. Figure 10 As shown, this is a structure where the front and rear wheel mechanisms are height-adjustable separately, allowing for adjustments based on different planes of movement, such as... Figure 11 The butt weld surface in the middle, and such Figure 12 For example, the lap weld surfaces, etc., require prior adjustment of the front or rear wheel height to facilitate easy movement on different planes. Figure 11 On the butt weld surface, because the weld surface is a lower stepped corrugated surface, lifting the rear wheel device first is more suitable for lifting the lower corrugated surface away from the detection surface, while the front wheel will not have too much resistance, making it easier to disengage from the magnetic force and move the magnetic flux leakage detection device easily; such as Figure 12 As shown, on the lap weld surface, since the weld surface is an upper wave-shaped surface, the front wheel device can be lifted first, which is more suitable for lifting the upper wave surface away from the magnetic constraint of the detection surface. Moreover, lifting the front wheel can reduce the resistance of the upper wave, making it easier to move the magnetic leakage detection device.

[0042] like Figure 8 and9 As shown in the height adjustment device includes motor 531, turbine 532, worm 533, the front wheel device 51 and the rear wheel device 52 of the wheel device 50 are fixed on the transverse rod 534 provided on the worm 533. The gear meshing structure of the worm gear can not only accurately control the height value during height adjustment, but also mechanically engage, lift the force, and will not have a buffer, which is suitable for strong magnetic force adsorption.

[0043] As shown in the figure, Figure 13 As shown in the figure, the magnetic flux leakage detection device further comprises a metal surface detection sensor 6 provided on the detection device shell, and the metal surface detection sensor is connected to the controller 9. After the metal surface detection sensor 6 detects the change of the metal plane, the controller 9 receives the signal and controls the height adjustment of the wheel device. The detection device 2 can be provided with a handle 7 to push the moving scanning detection structure, or as shown in the figure Figure 14 The controller 9 can be provided in the detection instrument 3, or a separate controller is installed in the detection device shell or the detection trolley, and the detection control panel is provided with different moving wheel device height adjustment modes under different conditions. For example, when the detection device needs to be removed, the front and rear wheels are simultaneously adjusted in height; as shown in the figure Figure 11 When the upper wave surface moves, the height of the front wheel device is adjusted first; as shown in the figure Figure 12 When the lower wave surface moves, the height of the rear wheel device is adjusted first.

[0044] The application also discloses a magnetic flux leakage detection method for evaluating defects of a large oil tank bottom plate metal surface and the like. The magnetic flux leakage detection device has a weak magnet device and a wheel device. The height of the wheel device of the detection device shell is adjusted while the weak magnet device forms a barrier and / or a reverse magnetic field, so that the synchronous operation method of the wheel device height adjustment device is realized while the adsorption magnetic force of the strong magnet is weakened. The specific detection method steps are as follows: a. Place the detection device on the metal detection surface, turn on the instrument to perform mobile magnetic flux leakage detection, collect and store the detection signal data, and analyze and evaluate the defect information output by the detection instrument;

[0045] b. When the metal surface detection sensor detects different changes in the detection surface, the corresponding concave-convex surface moving mode is started, the weak magnet device is started, and the height of the wheel device is adjusted, that is, the weak magnet coil is connected to the reverse direct current power supply, and the adjustment mode is selected, that is, when the upper wave surface moves, the height of the front wheel device is adjusted first, and when the lower wave surface moves, the height of the rear wheel device is adjusted first;

[0046] c. When the detection device needs to be removed, the disengagement mode is started, that is, the weak magnet device is started, the weak magnet coil is connected to the reverse direct current power supply, and the front wheel device and the rear wheel device are selected to be lifted at the same time.

[0047] The various modes can be started by manual button operation or automatic control through a setting in the detection instrument or a separate controller. The coil in the magnetizing device of the detection device forms a reverse magnetic field to reduce the attraction of the strong magnet to the detected metal piece, and the lifting wheel device on the shell of the detection device is used to pull up the detection device, thereby achieving the detection operation method of detaching from the detection surface or moving the detection surface when necessary.

[0048] In the b step, the concave-convex surface movement mode is set as follows: when the metal detection surface is a concave downward movement wave surface, the height of the rear wheel device is first adjusted, and then the height of the front wheel device is adjusted; when the metal detection surface is a convex movement wave surface, the height of the front wheel device is first adjusted, and then the height of the rear wheel device is adjusted; when the detection device needs to be removed, the height of the front wheel device and the height of the rear wheel device are simultaneously adjusted. The sensor detects the change of the metal surface, and automatically starts the corresponding mode, or manually selects different modes through a button, such as starting the upward wave surface movement mode, the downward wave surface movement mode, or the detachment mode. The corresponding upward wave surface movement mode is set to first lower the height of the front wheel device, the downward wave surface movement mode is set to first lower the height of the rear wheel device, and the detachment mode is set to simultaneously lower the height of the front wheel device and the height of the rear wheel device.

[0049] The above is one embodiment of the present application. In addition, it should be noted that equivalent or simple changes made in accordance with the structure, features and principles described in the patent concept are included in the protection scope of the patent.

Claims

1. A magnetic flux leakage detection device comprising a housing (5), a magnetizing device (21) consisting of a U-shaped strong magnet, and a magnetic flux leakage detection sensor (22) disposed at the center of the U-shaped magnet port of the magnetizing device (21), characterized in that Weak magnetic device (4) is arranged on the shell for supporting and moving the wheel device (50) of the detection device and the metal surface detection sensor on the shell of the detection device; The weak magnetic device (4) comprises a first magnetic yoke (41a) arranged at the N pole port (211) of the U-shaped strong magnet connected to the magnetizing device (21), a second magnetic yoke (41b) arranged at the S pole port (212), and a first excitation and demagnetization coil (42a) and a second excitation and demagnetization coil (42b) wound on the first magnetic yoke (41a) and the second magnetic yoke (41b) respectively; the first excitation and demagnetization coil (42a) and the second excitation and demagnetization coil (42b) are connected to the direct current power supply P respectively; The leakage magnetic detection probe applies a direct current power supply to generate a reverse magnetic field in the opposite direction of the magnetizing device, that is, the magnetic field N pole generated by the first excitation and demagnetization coil (42a) is connected to the N pole port (211), and the magnetic field S pole generated by the second excitation and demagnetization coil (42b) is connected to the S pole port (212). The wheel device (50) comprises a front wheel device (51) and a rear wheel device (52), and the wheel device (50) has a height adjusting function; the front wheel device (51) is provided with a first adjusting device, and the rear wheel device (52) is provided with a second adjusting device, which respectively adjusts the height of the front wheel device (51) and the rear wheel device (52), or simultaneously adjusts the height of the front wheel device (51) and the rear wheel device (52); The first adjusting device and the second adjusting device respectively comprise a motor (531), a turbine (532) and a worm (533), and the front wheel device (51) and the rear wheel device (52) of the wheel device (50) are respectively fixed to the transverse rod (534) arranged on the worm (533). The metal surface detection sensor is connected to the controller, and after the metal surface detection sensor detects the change of the metal plane, the controller receives the signal and controls the height adjustment of the wheel device.

2. A magnetic flux leakage detection device according to claim 1, characterised in that The first excitation and demagnetization coil (42a) and the second excitation and demagnetization coil (42b) are connected to the direct current power supply P through the first switch K1 and the second switch K2 respectively.

3. The magnetic flux leakage detection apparatus of claim 1, wherein The height H of the first magnetic yoke (41a) and the second magnetic yoke (41b) is any value between 3 and 20 mm.

4. The magnetic flux leakage detection apparatus of claim 1, wherein During normal detection, the leakage magnetic detection probe applies a direct current power supply to generate a forward magnetic field in the same direction as the magnetizing device, that is, the magnetic field S pole generated by the first excitation and demagnetization coil (42a) is connected to the N pole port (211), and the magnetic field N pole generated by the second excitation and demagnetization coil (42b) is connected to the S pole port (212).

5. A magnetic flux leakage detection method using the magnetic flux leakage detection apparatus according to any one of claims 1 to 4, characterized by By forming a barrier and / or a reverse magnetic field through the weak magnetic device, the height of the wheel device of the detection device shell is adjusted, so that the synchronous operation method of weakening the adsorption magnetic force of the strong magnet and the height adjustment of the wheel device is realized; the specific detection method steps are as follows: a. Place the detection device on the metal detection surface, turn on the instrument to perform mobile magnetic flux leakage detection, collect and store detection signal data, and output defect information by analyzing and evaluating the detection instrument; b. When the metal surface detection sensor detects different changes in the detection surface, the corresponding concave-convex surface movement mode is started, the weak magnetic device is started, and the height of the wheel device is adjusted, that is, the weak magnetic coil is connected to the reverse DC power supply, and the adjustment mode is selected, that is, when the upper wave surface moves, the height of the front wheel device is adjusted first, and when the lower wave surface moves, the height of the rear wheel device is adjusted first; c. When the detection device needs to be removed, the disengagement mode is started, that is, the weak magnetic device is started to connect the weak magnetic coil to the reverse DC power supply, and the height of the front wheel device and the rear wheel device is adjusted at the same time.

6. A method of magnetic flux leakage detection according to claim 5, characterised in that The concave-convex surface movement mode in step b is set as follows: when the metal detection surface is a concave moving wave surface, the height of the rear wheel device is adjusted first, and then the height of the front wheel device is adjusted; when the metal detection surface is a convex moving wave surface, the height of the front wheel device is adjusted first, and then the height of the rear wheel device is adjusted; when the detection device needs to be removed, the height of the front wheel device and the rear wheel device is adjusted at the same time.

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