External liftable far-field eddy current probe and detection method thereof

Abstract

The invention relates to the technical field of nondestructive testing, in particular to an external liftable far-field eddy current probe and a detection method thereof.The external liftable far-field eddy current probe comprises a supporting base and an F-type electromagnetic shielding structure, the F-type electromagnetic shielding structure is nested in the supporting base, and the supporting base mainly functions as the F-type electromagnetic shielding structure; the F-type electromagnetic shielding structure comprises an electromagnetic shielding part, an excitation coil, an F-type pure iron body and a detection coil, the excitation coil is wrapped by the electromagnetic shielding part and embedded in the bottom of one end of the F-type pure iron body, and the detection coil is embedded in a supporting base located below the other end of the F-type pure iron body. According to the far-field eddy current probe, through the arrangement of the F-type electromagnetic shielding structure, direct magnetic field energy is effectively shielded, meanwhile, indirect magnetic field energy is effectively exerted, the indirect magnetic field energy smoothly penetrates through the flat plate twice, the detection sensitivity of the far-field eddy current probe is improved, and the detection efficiency and the detection accuracy are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of non-destructive testing, and in particular to an externally mounted detachable far-field eddy current probe and a testing method thereof. Background Art

[0002] Remote-field eddy current testing (RFT) is a low-frequency eddy current testing technique that is unaffected by the skin effect and has equal sensitivity to both the inner and outer pipe walls. Conventional RFT probes used for pipeline testing are internal-penetrating probes, often requiring equipment downtime to insert the probe into the pipe.

[0003] For pressure equipment in the petrochemical and power industries, in-service testing is essential to ensure long-term continuous operation due to the unique characteristics of the media they contain. Existing eddy current testing probes cannot simultaneously meet the requirements of external testing and probe detachability. Therefore, there is an urgent need for an external, detachable, remote-field eddy current probe. Summary of the Invention

[0004] The main purpose of the present invention is to overcome the deficiencies in the prior art and to provide an externally mounted, detachable far-field eddy current probe and a detection method thereof.

[0005] The technical solution adopted by the present invention to achieve its technical objectives is: an external, detachable far-field eddy current probe, comprising a support base and an F-shaped electromagnetic shielding structure, wherein the F-shaped electromagnetic shielding structure is nested in the support base, and the main function of the support base is to support the F-shaped electromagnetic shielding structure; The F-type electromagnetic shielding structure includes an electromagnetic shielding component, an excitation coil, an F-type pure iron body and a detection coil; The excitation coil is wrapped by the electromagnetic shielding component and embedded in the bottom of one end of the F-shaped pure iron body; The detection coil is nested in a support base below the other end of the F-shaped pure iron body.

[0006] Preferably, the detection coil is electrically connected to a detector wire and a converter wire, wherein the detector wire is electrically connected to an electromagnetic detector, and the converter wire is electrically connected to a remote-field eddy current converter. By connecting the detector wire to the electromagnetic detector and the converter wire to the remote-field eddy current converter, a flat-panel remote-field eddy current detection system can be connected, thereby correctly setting parameter values and testing whether the probe is functioning properly.

[0007] Preferably, the F-type electromagnetic shielding structure is made of a material with high relative magnetic permeability and high electrical conductivity.

[0008] Preferably, the electromagnetic shielding component includes a pure iron layer and a copper layer, and is wrapped and connected in the order of inner and outer layers of pure iron layer, copper layer, and pure iron layer, and the excitation coil is wrapped in the innermost pure iron layer.

[0009] Preferably, the pure iron layer, the copper layer and the pure iron layer in the electromagnetic shielding component are arranged in a thickness ratio of 1:2:1.

[0010] It should be pointed out here that the shielding effect of the electromagnetic shielding structure is the key to the indirect magnetic field energy excited by the excitation coil being able to penetrate the ferromagnetic plate twice, and the shielding effect of the electromagnetic shielding structure depends on the shape and material of the electromagnetic shielding structure; Therefore, electromagnetic shielding structures utilize materials with both high relative magnetic permeability and high electrical conductivity. Relative magnetic permeability results in low magnetic resistance, which guides the propagation of the primary magnetic field within the electromagnetic shielding structure. High electrical conductivity materials induce eddy currents on their surfaces. These induced eddy currents create a secondary magnetic field that hinders the propagation of the primary magnetic field, achieving a shielding effect.

[0011] The material of the electromagnetic shielding structure has the material properties of high relative magnetic permeability and high electrical conductivity at the same time, which has a better shielding effect. However, there are few materials that have both properties. Therefore, a multi-layer shielding structure is used to make it have both high relative magnetic permeability and high electrical conductivity. After comparing the amplitude and phase of the far field in the electromagnetic shielding structures of various materials, the electromagnetic shielding structure selected is pure iron layer + copper layer + pure iron layer.

[0012] However, when the far-field eddy current probe is lifted off, the magnetic field energy generated by the excitation coil is less likely to penetrate downward into the ferromagnetic flat plate. Instead, it tends to propagate to the sides along the air gap between the far-field eddy current probe and the ferromagnetic flat plate. This is because magnetic field energy propagates faster in air than in the ferromagnetic flat plate. Therefore, an F-shaped pure iron body is added to the electromagnetic shielding structure, allowing the indirect magnetic field energy to penetrate the ferromagnetic flat plate twice, thus achieving far-field eddy current defect detection.

[0013] Preferably, the excitation coil and the detection coil are arranged in parallel to facilitate smooth propagation of indirect magnetic field energy.

[0014] Preferably, a moving device is provided on the top of the far-field eddy current probe, and the far-field eddy current probe is invertedly mounted on the moving device; The moving device includes a fixed plate, a roller is provided below the fixed plate, and one side of the roller is rotatably connected to a rod; A pull rod is provided between the fixed plate and the roller. One side of the pull rod is slidably connected to the fixed plate, and the other side is attached to the roller. The pull rod is tightly attached to the roller. By pulling the pull rod, a group of rollers are driven to roll on the rod body.

[0015] Preferably, one end of the rod body is fixedly connected to a first telescopic rod, the first telescopic rod is configured to be telescopic in multiple stages, and the telescopic end is fixedly connected to the rod body.

[0016] Preferably, the rollers are provided in three groups and are arranged in a ring array around the rod body, wherein one group of the rollers is fixedly mounted on a fixed plate.

[0017] Preferably, the three groups of rollers are fixedly connected as one body by providing a connecting plate, and the connecting plate is provided as a bent plate.

[0018] Preferably, an adjustment device is provided between the fixed plate and the array probe, the adjustment device comprising a bending plate, the bottom of the transverse plate portion of the bending plate is fixedly connected to the fixed plate, a first slide is fixedly mounted on the transverse plate portion of the bending plate, and a second slide is fixedly mounted on one side of the first slide; A first slider is slidably connected to the inside of the first slide plate, a rotating shaft is installed on the inner side of the first slider, a movable plate is movably connected to the rotating shaft, one end of the movable plate is movably connected to the second slider, one end of the movable plate is movably sleeved on the rotating shaft, and the other end is rotatably connected to the inner side of the second slider, a pad is fixedly installed on the inner side of the second slider, and one end of the pad is fixedly installed with a movable plate.

[0019] Preferably, the adjustment device also includes two groups of probe mounting slot plates, one end of the two groups of probe mounting slot plates are hinged, and the hinge is fixed to the movable plate by a pin, and the two groups of probe mounting slot plates can move freely around the hinge; wherein, two groups of far-field eddy current probes are correspondingly arranged and are inverted and embedded in the probe mounting slot plates.

[0020] The other end of the two sets of probe mounting slot plates is connected to a bearing by setting a column. The bearing is sleeved on the column. One side of the bearing is hinged with a hook rod. Through the setting of the bearing, the hook rod can be rotated. A positioning column is set on one side of the hook rod. The positioning column is fixedly mounted on the vertical plate part of the bent plate. A spring is provided between the two groups of inverted hook rods for connection.

[0021] Preferably, a second telescopic rod is fixedly mounted on one end of the horizontal plate portion of the bending plate, and a telescopic end of the second telescopic rod is fixedly connected to the rotating shaft, so that one group of the rotating shafts can be driven to move by the second telescopic rod.

[0022] The present invention also provides a detection method for an externally mounted, detachable far-field eddy current probe, which uses any one of the far-field eddy current probes described above and specifically includes the following steps: S1. Before testing, connect the detector wire to the electromagnetic detector, connect the converter wire to the far-field eddy current converter, enter the flat-plate far-field eddy current testing system, correctly set the parameter values, and test whether the probe can work normally; S2. During the inspection, the far-field eddy current probe is placed vertically and closely against the surface of the ferromagnetic flat member 30 and passes through the target position at a constant speed to complete the defect detection; S3. Reading the amplitude and phase of a detection signal on a software detection window of a computer, wherein the detection signal is an induced voltage signal of the detection coil; By analyzing the amplitude and phase of the induced voltage signal of the detection coil, the inner and outer wall defects and thickness changes of ferromagnetic components can be effectively detected. Not only can accurate flat plate defects be identified, but also the defect size can be accurately quantified by detecting the signal phase information.

[0023] Compared with the prior art, the present invention has the following beneficial effects: This external, detachable far-field eddy current probe effectively shields direct magnetic field energy through the setting of an F-type electromagnetic shielding structure, while effectively exerting indirect magnetic field energy, allowing the indirect magnetic field energy to smoothly penetrate the flat plate twice, increasing the detection sensitivity of the far-field eddy current probe and improving detection efficiency and accuracy.

[0024] This external, detachable far-field eddy current probe adopts an F-type structure and "pure iron + copper + pure iron" multi-layer material, and has high relative magnetic permeability and high electrical conductivity characteristics.

[0025] Furthermore, innovations in the electromagnetic shielding structure and materials enable the probe to be lifted off the surface of ferromagnetic plates and metal pipes for defect detection. Furthermore, the probe can be kept in close contact with the surface of the object being measured and remain perpendicular to the object, preventing missed or misjudged defects due to probe slippage. This external, detachable, far-field eddy current probe can be used for external testing, and can be used for in-service testing of equipment or pipelines, saving downtime for testing. The advantages are more obvious under conditions of tight time and large workload. This external, detachable far-field eddy current probe has a small overall size, high precision, is easy to carry, and is simple to operate. It does not rely on the operator's experience and technical level, is easy to obtain signal change characteristics, and has a promising future for promotion.

[0026] This external, detachable far-field eddy current probe can make small and precise adjustments to the position of the array probe through the setting of the moving device, which facilitates precise adjustment and positioning; the detection range and detection height of the array probe can be adjusted through the setting of the adjusting device; and the mutual coordination of the moving device and the adjusting device enables the far-field eddy current probe to have multiple detection movement modes, thereby increasing the applicability of the far-field eddy current probe. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of an external, detachable far-field eddy current probe.

[0028] Figure 2 This is a schematic diagram of the bottom structure of an external, liftable far-field eddy current probe.

[0029] Figure 3 This is the detection principle diagram of an external, detachable far-field eddy current probe.

[0030] Figure 4 It is a schematic diagram of the main cross-sectional structure of the mobile device.

[0031] Figure 5 It is a side structural schematic diagram of the mobile device.

[0032] Figure 6 It is a schematic diagram of the three-dimensional structure of the adjusting device.

[0033] Figure 7 This is a schematic diagram of the main structure of the regulating device.

[0034] Figure 8 This is a schematic diagram of the top view of the structure of two sets of array probes, fixing plates and adjustment devices.

[0035] in: 10-support base; 20-F type electromagnetic shielding structure; 21-electromagnetic shielding component; 22-copper layer; 23-excitation coil; 24-pure iron layer; 25-F type pure iron body; 26-detection coil; 27-detector wire; 28-converter wire; 30-ferromagnetic flat member; 40-fixed plate; 41-pull bar; 42-roller; 43-rod body; 44-connecting plate; 45-first telescopic rod; 50-bending plate; 51-first slide plate; 52-second slide plate; 53-first slider; 54-rotating shaft; 55-movable plate; 56-second slider; 57-second telescopic rod; 58-pad; 59-movable plate; 510-bearing; 511-spring; 512-positioning column; 513-hook rod; 514-probe mounting slot plate DETAILED DESCRIPTION

[0036] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is typically placed when in use. These terms are intended solely to facilitate the description of the present invention and to simplify the description, and are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0037] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0038] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and examples. However, it should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the present invention. Example 1

[0039] See also Figure 1-Figure 3 An external, detachable far-field eddy current probe comprises a support base 10 and an F-type electromagnetic shielding structure 20. The F-type electromagnetic shielding structure 20 is nested in the support base 10. The material of the F-type electromagnetic shielding structure 20 adopts a material with high relative magnetic permeability and high electrical conductivity. The main function of the support base 10 is to support the F-type electromagnetic shielding structure 20.

[0040] The F-type electromagnetic shielding structure 20 includes an electromagnetic shielding component 21, an excitation coil 23, an F-type pure iron body 25, and a detection coil 26; the excitation coil 23 is wrapped by the electromagnetic shielding component 21 and embedded in the bottom of one end of the F-type pure iron body 25; The electromagnetic shielding component 21 includes a pure iron layer 24 and a copper layer 22, and is wrapped and connected in the order of the pure iron layer 24, the copper layer 22, and the pure iron layer 24. The excitation coil 23 is wrapped in the innermost pure iron layer 24. The thickness of the pure iron layer 24, the copper layer 22, and the pure iron layer 24 in the electromagnetic shielding component 21 is arranged in a ratio of 1:2:1.

[0041] It should be pointed out here that the shielding effect of the electromagnetic shielding structure is the key to the indirect magnetic field energy excited by the excitation coil being able to penetrate the ferromagnetic plate twice, and the shielding effect of the electromagnetic shielding structure depends on the shape and material of the electromagnetic shielding structure; Therefore, electromagnetic shielding structures utilize materials with both high relative magnetic permeability and high electrical conductivity. Relative magnetic permeability results in low magnetic resistance, which guides the propagation of the primary magnetic field within the electromagnetic shielding structure. High electrical conductivity materials induce eddy currents on their surfaces. These induced eddy currents create a secondary magnetic field that hinders the propagation of the primary magnetic field, achieving a shielding effect.

[0042] The material of the electromagnetic shielding structure has the material properties of high relative magnetic permeability and high electrical conductivity at the same time, which has a better shielding effect. However, there are few materials that have both properties. Therefore, a multi-layer shielding structure is used to make it have both high relative magnetic permeability and high electrical conductivity. After comparing the amplitude and phase of the far field in electromagnetic shielding structures made of various materials, the selected electromagnetic shielding structure is pure iron layer 24 + copper layer 22 + pure iron layer 24 .

[0043] However, when the far-field eddy current probe is lifted off, the magnetic field energy generated by the excitation coil does not easily penetrate downward through the ferromagnetic flat member 30. Instead, it tends to propagate to the sides along the air gap between the far-field eddy current probe and the ferromagnetic flat member 30. This is because magnetic field energy propagates faster in air than in the ferromagnetic flat member 30. Therefore, an F-shaped pure iron body 25 is added to the electromagnetic shielding structure, allowing the indirect magnetic field energy to penetrate the ferromagnetic flat member 30 twice, thus achieving far-field eddy current defect detection.

[0044] The detection coil 26 is nested in the support base 10 below the other end of the F-shaped pure iron body 25. During the actual detection process, the detection coil 26 of the far-field detection probe is set at the starting section of the far-field area, so that the probe size is as small as possible.

[0045] The detection coil 26 is electrically connected to a detector wire 27 and a converter wire 28. The detector wire 27 is electrically connected to the electromagnetic detector, and the converter wire 28 is electrically connected to the far-field eddy current converter. By connecting the detector wire 27 to the electromagnetic detector and the converter wire 28 to the far-field eddy current converter, it is possible to connect to the flat-plate far-field eddy current testing system, thereby correctly setting parameter values and testing whether the probe is working properly.

[0046] The excitation coil 23 and the detection coil 26 are arranged in parallel to facilitate the smooth propagation of indirect magnetic field energy.

[0047] The working principle and specific use process of the external detachable far-field eddy current probe are as follows: Figure 3 As shown, the "F"-type electromagnetic shielding structure consists of "pure iron layer 24 + copper layer 22 + pure iron layer 24" and an F-type pure iron body 25. After the low-frequency current is applied, the excitation coil 23 generates direct and indirect magnetic field energy. The electromagnetic shielding component 21 (pure iron layer 24 + copper layer 22 + pure iron layer 24) is used to shield the direct magnetic field energy, so that the indirect energy can smoothly penetrate the ferromagnetic flat member 30 twice and return to the same side of the excitation coil 23, realizing the far-field eddy current phenomenon.

[0048] The indirect magnetic field energy carries relevant wall thickness information in the process of propagating a certain distance along the outer wall of the ferromagnetic flat component 30 and returning to the same side of the excitation coil 23. By analyzing the amplitude and phase of the induced voltage signal of the detection coil 26, the inner and outer wall defects and thickness changes of the ferromagnetic component 30 can be effectively detected. Example 2

[0049] See also Figure 4-Figure 5 On the basis of the above embodiment, the externally mounted detachable far-field eddy current probe has a moving device provided on the top of the far-field eddy current probe, and the far-field eddy current probe is invertedly mounted on the moving device; The moving device includes a fixed plate 40, a roller 42 is provided below the fixed plate 40, one side of the roller 42 is rollingly connected to a rod body 43, one end of the rod body 43 is fixedly connected to a first telescopic rod 45, the first telescopic rod 45 is set to multi-stage telescopic, and the telescopic end is fixedly connected to the rod body 43.

[0050] There are three groups of rollers 42 arranged in a ring array around the rod body 43, wherein one group of rollers 42 is fixedly mounted on the fixed plate 40. The three groups of rollers 42 are fixedly connected as a whole by a connecting plate 44, which is a bent plate.

[0051] A pull strip 41 is provided between the fixed plate 40 and the roller 42. One side of the pull strip 41 is slidably connected to the fixed plate 40, and the other side is attached to the roller 42. The pull strip 41 is tightly attached to the roller 42. By pulling the pull strip 41, it drives a group of rollers 42 to roll on the rod body 43.

[0052] Specifically, when in use, the first telescopic rod 45 can be fixed in position first, and the far-field eddy current probe can be brought close to the outer wall of the pipe. The detection position of the far-field eddy current probe can be moved by the first telescopic rod 45. When it is necessary to adjust the detection position slightly and accurately, the pull rod 41 can be manually pulled, and the pull rod 41 can drive a group of rollers 42 to roll on the rod body 43, so that the other two groups of rollers 42 are driven on the rod body 43, so that the far-field eddy current probe can be adjusted slightly and accurately in position.

[0053] The solution in this embodiment can be selectively combined with the solutions in other embodiments for use. Example 3

[0054] See also Figure 6-Figure 8 Based on the above embodiment, the externally mounted detachable far-field eddy current probe, An adjustment device is provided between the fixed plate 40 and the far-field eddy current probe, and the adjustment device includes a bending plate 50. The bottom of the horizontal plate portion of the bending plate 50 is fixedly connected to the fixed plate 40. A first slide plate 51 is fixedly mounted on the horizontal plate portion of the bending plate 50, and a second slide plate 52 is fixedly mounted on one side of the first slide plate 51. A first slider 53 is slidably connected to the inside of the first slider 51, and a rotating shaft 54 is installed on the inner side of the first slider 53. A movable plate 59 is movably connected to the rotating shaft 54, and one end of the movable plate 59 is movably connected to the second slider 56. One end of the movable plate 59 is movably sleeved on the rotating shaft 54, and the other end is rotatably connected to the inner side of the second slider 56. A pad 58 is fixedly installed on the inner side of the second slider 56, and a movable plate 55 is fixedly installed on one end of the pad 58.

[0055] The adjustment device also includes two sets of probe mounting slot plates 514, one end of the two sets of probe mounting slot plates 514 are hinged, and the hinge is fixed on the movable plate 55 by a pin. The two sets of probe mounting slot plates 514 can move freely around the hinge; among them, two sets of far-field eddy current probes are correspondingly provided and are inverted and embedded in the probe mounting slot plates 514.

[0056] The other end of the two sets of probe mounting slot plates 514 is connected to a bearing 510 through a column. The bearing 510 is sleeved on the column. A hook rod 513 is hinged on one side of the bearing 510. The setting of the bearing 510 allows the right end of the hook rod 513 to rotate. A positioning column 512 is provided on one side of the hook rod 513. The positioning column 512 is fixedly mounted on the vertical plate portion of the bending plate 50. A spring 511 is provided between the two groups of inverted hook rods 513 for connection. The spring 511 can make the inverted hook rods 513 fit on the positioning column 512 .

[0057] Furthermore, a second telescopic rod 57 is fixedly installed on one end of the horizontal plate portion of the bending plate 50, and the telescopic end of the second telescopic rod 57 is fixedly connected to the rotating shaft 54. The second telescopic rod 57 can drive one group of the rotating shafts 54 to move.

[0058] Specifically, during use, one end of the two sets of probe mounting slot plates 514 can be hinged, and the hinge can be fixed on the movable plate 55 by a pin. By telescoping the second telescopic rod 57, the second telescopic rod 57 drives a set of rotating shafts 54 to move, thereby driving the first slider 53 to move in the first slide plate 51.

[0059] When the first slider 53 moves to the right, the rotating shaft 54 pulls one end of the movable plate 59 to move to the right. At this time, due to the inclination of the movable plate 59, the height positions of the second slider 56 and the movable plate 55 are lowered; when the first slider 53 is continued to move, the second slider 56 can slide inside the second slide plate 52, thereby pulling the movable plate 55 to the right, and then the two sets of probe mounting slot plates 514 also move to the right. At the same time, the probe mounting slot plates 514 pull the right ends of the hook rods 513 to move to the right. Under the action of the spring 511, the left ends of the two sets of hook rods 513 can be hooked on the positioning column 512, which can cause the two sets of probe mounting slot plates 514 and the far-field eddy current probes to tilt, forming a structure similar to an "eight" shape, so that the far-field eddy current probe can finely adjust the external detection range and detection height of the pipeline, making it easier for the far-field eddy current probe to fit or move away from the outer wall of the pipeline.

[0060] When the first slider 53 moves to the left, the first slider 53 slowly lifts the movable plate 59, so that the second slider 56 and the movable plate 55 are pressed against the vertical plate part of the bending plate 50, and the first slider 53 continues to move to the left, so that the movable plate 59 continues to rise, and the left ends of the two sets of inverted hook rods 513 can be pressed against the positioning column 512, and the probe mounting slot plate 514 and the far-field eddy current probe can be supported, thereby adjusting the detection range and detection height of the far-field eddy current probe, which facilitates the far-field eddy current probe to fit the outer wall of the pipeline.

[0061] It should be noted that, by disposing the bearing 510 , the right end of the hook rod 513 can be rotated, so that even if the height position of the movable plate 55 rises or falls, it is convenient to cooperate with the far-field eddy current probe.

[0062] The solution in this embodiment can be selectively combined with the solutions in other embodiments for use. Example 4

[0063] See also Figure 1-Figure 3 On the basis of the above embodiment, an embodiment of the present invention further provides a detection method of an externally mounted detachable far-field eddy current probe, which uses the above-mentioned far-field eddy current probe and specifically includes the following steps: S1. Before testing, connect the detector wire 27 to the electromagnetic detector, connect the converter wire 28 to the far-field eddy current converter, enter the flat-plate far-field eddy current testing system, correctly set the parameter values, and test whether the probe can work normally; S2. During the inspection, the far-field eddy current probe is placed vertically and closely against the surface of the ferromagnetic flat member 30 and passes through the target position at a constant speed to complete the defect detection; S3. Reading the amplitude and phase of the detection signal on the computer software detection window, wherein the detection signal is the induced voltage signal of the detection coil 26; By analyzing the amplitude and phase of the induced voltage signal of the detection coil 26, the inner and outer wall defects and thickness changes of the ferromagnetic component 30 can be effectively detected, which not only enables accurate flat plate defect identification, but also enables accurate quantification of defect size by detecting signal phase information.

[0064] The solution in this embodiment can be selectively combined with the solutions in other embodiments for use.

[0065] It should be noted that although the above embodiments have been described herein, this does not limit the scope of patent protection of the present invention. Therefore, based on the innovative concept of the present invention, changes and modifications to the embodiments described herein, or equivalent structures, equivalent processes, or equivalent functional transformations made using the contents of the present invention's specification and drawings, and direct or indirect application of the above technical solutions to other related technical fields, are all included in the scope of protection of the present invention's patent.

Claims

1. An external, detachable, far-field eddy current probe, characterized by: It comprises a support base (10) and an F-shaped electromagnetic shielding structure (20), wherein the F-shaped electromagnetic shielding structure (20) is nested in the support base (10); The F-type electromagnetic shielding structure (20) comprises an electromagnetic shielding component (21), an excitation coil (23), an F-type pure iron body (25), and a detection coil (26); The excitation coil (23) is wrapped by the electromagnetic shielding component (21) and embedded in the bottom of one end of the F-shaped pure iron body (25); The detection coil (26) is nested in a support base (10) located below the other end of the F-shaped pure iron body (25).

2. The externally mounted, detachable far-field eddy current probe according to claim 1, characterized in that: The detection coil (26) is electrically connected to a detector wire (27) and a converter wire (28), the detector wire (27) is electrically connected to the electromagnetic detector, and the converter wire (28) is electrically connected to the far-field eddy current converter.

3. The externally mounted, detachable far-field eddy current probe according to claim 1, characterized in that: The F-type electromagnetic shielding structure (20) is made of a material with high relative magnetic permeability and high electrical conductivity.

4. The externally mounted, detachable far-field eddy current probe according to claim 3, characterized in that: The electromagnetic shielding component (21) comprises a pure iron layer (24) and a copper layer (22), and is wrapped and connected in the order of inner and outer layers of the pure iron layer (24), the copper layer (22), and the pure iron layer (24), and the excitation coil (23) is wrapped in the innermost pure iron layer (24).

5. The externally mounted, detachable far-field eddy current probe according to claim 4, characterized in that: The pure iron layer (24), the copper layer (22), and the pure iron layer (24) in the electromagnetic shielding component (21) are arranged in a thickness ratio of 1:2:

1.

6. The externally mounted, detachable far-field eddy current probe according to claim 1, characterized in that: The excitation coil (23) and the detection coil (26) are arranged in parallel to facilitate smooth propagation of indirect magnetic field energy.

7. A detection method for an externally mounted detachable far-field eddy current probe, which uses the far-field eddy current probe according to any one of claims 1 to 6, characterized in that: The specific steps include: S1. Before testing, connect the detector wire (27) to the electromagnetic detector, connect the converter wire (28) to the far-field eddy current converter, enter the flat-plate far-field eddy current testing system, correctly set the parameter values, and test whether the probe can work normally; S2. During the inspection, the far-field eddy current probe is placed vertically and closely against the surface of the ferromagnetic flat member (30), and passes through the target position at a constant speed and smoothly, thereby completing the defect inspection; S3. Read the amplitude and phase of the detection signal on the software detection window of the computer, wherein the detection signal is the induced voltage signal of the detection coil (26).

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