Micro-precision eddy current testing method and device thereof

Abstract

The application discloses a micro-precision eddy current detection method and a detection device thereof, which is used for eddy current nondestructive detection of micro holes (11) with different shapes on an aero turbine engine rotor blade (1). The detection device (2) is connected to a multi-channel eddy current detection instrument, and comprises an eddy current detection instrument (3), a probe shell (21) and a flexible PCB (22). The flexible PCB is fixed to the end of the probe shell (21) close to a detection surface, and an eddy current detection sensor (221) is arranged on the flexible PCB (22). The flexible PCB (22) is characterized in that an elastic shielding film (23) is arranged on the side close to the detected object, and a supporting device (24) is arranged on the side away from the detected object. The application sets an elastic shielding film with micro holes on the detection surface of the flexible PCB eddy current detection sensor, elastically supports and opens the micro holes on the elastic shielding film, thereby forming a micro aperture detection window area on the detection surface of the flexible PCB eddy current detection sensor, and realizing the precise eddy current nondestructive detection of a micro area.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of non-destructive testing, in particular to a micro-precision eddy current testing method and device for blade eddy current testing of an aircraft turbine engine or the like. BACKGROUND

[0002] In the non-destructive testing of some metal devices, it is necessary to position and detect defects in a small area, such as the detection of turbine rotor blades of an aircraft engine. Gas film cooling is designed with a large number of micro-holes with a diameter of 0.1-0.8mm and a depth of 3mm or more on the surface profile of the turbine rotor blade. Through the convection in the micro-holes, a thin layer of cold gas film is formed on the surface of the part to achieve the purpose of isolating the high-temperature gas flow and protecting the part. The gas film hole has the characteristics of small aperture, large number, high depth-diameter ratio, complex space angle, and high quality requirement. At present, there is no ideal solution for its accurate detection.

[0003] Moreover, modern non-destructive testing increasingly emphasizes visualization. From mechanical scanning imaging to electronic array scanning imaging, there are endless possibilities. In the field of electromagnetic eddy current testing, the above imaging methods have been mature. However, there is a demand for micro-precision eddy current scanning imaging, such as micro-hole cracks (0.5mm-1.0mm) on the curved surface of the turbine rotor blade of an aircraft engine, especially the edge defects of micro-holes with different shapes. Because the conventional eddy current probe has a diameter greater than 0.8mm, it is difficult to use conventional eddy current scanning imaging methods.

[0004] In view of the above shortcomings, the present application adopts the following technical solutions. SUMMARY

[0005] The purpose of the present application is to provide a micro-precision eddy current testing method and device. The technical solutions disclosed are as follows:

[0006] A micro-precision eddy current testing method for non-destructive eddy current testing of micro-holes (11) with different shapes on an aircraft turbine engine rotor blade (1), characterized in that a layer of elastic shielding film with micro-holes is arranged on the detection surface of the flexible PCB eddy current detection sensor, the micro-holes on the elastic shielding film are expanded by elasticity, thereby forming a micro-aperture detection window area on the detection surface of the flexible PCB eddy current detection sensor, and realizing the technical method of micro-area eddy current non-destructive testing. The specific steps are as follows:

[0007] a. Aperture parameter presetting: through the demand of the surface shape structure of the detected object aperture crack, the micro-hole window area required for the eddy current detection surface is evaluated and calculated;

[0008] b. Micropore adjustment setting: By pushing and pulling the elastic shielding film, it is elastically deformed towards the detection surface. The elastic deformation opens micropores placed on the elastic shielding film, and the adjustment forms a pore-type detection window;

[0009] c. Actual inspection: The eddy current detection sensor on the flexible PCB board detects the defect information of the object being inspected through the micropores on the elastic shielding film;

[0010] d. Detection Data Analysis: Acquire signal data from eddy current sensors corresponding to the micropores of the expanded elastic shielding membrane, and evaluate the defect parameters at the precise locations of the micropores. This can be achieved through imaging analysis and other methods to realize precise eddy current detection, evaluation, and analysis of minute areas.

[0011] The microporous elastic shielding film is a membrane-type electromagnetic shielding layer made of an elastic conductive material. Tiny pores are set in the film layer. When the elastic shielding film is in a normal state, the elastic contraction of the micropores almost fills the gaps between the micropores, eliminating the gaps and creating a continuous electromagnetic seal. No electromagnetic wave leakage will occur. That is, the eddy current detection sensor on the PCB board and the device under test are shielded and isolated, and no detection signal is generated.

[0012] When the elastic shielding film is stretched to a certain deformation, the micropores overcome the elastic force of the elastic film to form gaps. When the gaps reach a certain aperture, electromagnetic leakage occurs. The electromagnetic signal of the eddy current detection sensor on the PCB board passes through the micropores to form electromagnetic detection signals in a tiny area.

[0013] Furthermore, the micropore adjustment setting also includes adjusting the diameter of the micropores in the elastic shielding film by adjusting the degree of stretching deformation of the elastic shielding film, thereby adjusting the actual area of ​​the tiny region for eddy current non-destructive testing. That is, the more the elastic shielding film is pushed towards one side of the detection surface, the greater the degree of stretching elastic deformation, the larger the gap opened by the micropores, and the relatively larger the detection micropore window formed on the elastic shielding film by the eddy current detection sensor coil on the flexible PCB board. For example, the rotor blades of aero-turbine engines have numerous tiny holes with diameters of 0.1–0.8 mm and depths of over 3 mm. Since conventional eddy current detection sensor coils can only be made as small as 0.8 mm, they cannot accurately detect defects such as tiny cracks within such a small area, especially the tiny cracks around the blade holes. This invention addresses this by using micropores formed by an elastic shielding film. The size of the micropores in the shielding film can be adjusted according to the needs of the blade holes. The shielding film is aligned with the tiny area in a window-like manner, enabling precise detection of defects such as tiny holes on aero-turbine engine rotor blades, particularly small cracks around the blade holes. This allows for the detection of defects before the small cracks expand and affect the airflow of the aero-engine, thus enabling early detection of potential safety hazards.

[0014] Furthermore, it also includes using a fixed threaded structure to move a helical push rod to push the flexible PCB board away from the detection surface, thereby stretching the elastic shielding film, elastically opening the micropores, and adjusting the diameter of the micropores. The fixed thread, i.e., the pitch, is a fixed value, and the vertical movement distance during rotation adjustment is also a fixed value.

[0015] Furthermore, it also includes calibrating the fixed thread pitch quantitative value by using the specific aperture parameter value required by the object being tested, thereby adjusting the aperture of the micropore by adjusting the pitch quantitative value.

[0016] Furthermore, the eddy current detection sensor on the flexible PCB board is an array-type planar spiral coil sensor, where each coil detects and acquires detection information corresponding to a micro-hole on the elastic shielding diaphragm. The array-arranged planar spiral coils on the flexible PCB board, with each coil corresponding to a micro-hole detection window, enable large-area scanning detection.

[0017] Furthermore, the flexible PCB board eddy current detection sensor is a planar spiral coil sensor. The planar spiral coil corresponds to several micro-holes on the elastic shielding film. The eddy current detection coil sequentially acquires detection information of the area corresponding to the micro-holes. Each planar spiral coil of the flexible PCB board eddy current detection sensor corresponds to multiple micro-holes, and the multi-channel eddy current detector sequentially acquires detection information from each micro-hole by sequentially detecting the micro-holes on the elastic shielding film. This is more suitable for the one-time detection requirements of densely packed micro-areas.

[0018] The present invention also discloses a micro-area precision eddy current detection device for non-destructive testing of eddy currents in tiny holes (11) of varying shapes on rotor blades (1) of an aero-turbine engine. The detection device (2) is connected to a multi-channel eddy current testing instrument and includes an eddy current testing instrument (3), a probe housing (21), and a flexible PCB board (22). The flexible PCB board is fixed inside the probe housing (21) at the end near the detection surface, and an eddy current detection sensor (221) is disposed on the flexible PCB board (22). The feature is that an elastic shielding film (23) is disposed on the side of the flexible PCB board (22) near the object being tested, and a spreading device (24) is disposed on the side away from the object being tested. The elastic shielding film (23) is provided with micro-holes (231). When the spreading device (24) pushes the flexible PCB board (22) toward the detection surface, the elastic shielding film (23) elastically deforms and spreads the micro-holes (231) to form an eddy current detection window.

[0019] Furthermore, the expansion device (24) also includes a bracket (241), and the flexible PCB board (22) is elastically fixed to the bracket (241). The bracket (241) is rotatably connected to the inner side of the probe housing (21) by a fixing thread (242), which pushes the push rod (243) fixed on the bracket (241) to move up and down. The flexible PCB board (22) can be configured to be elastically fixed to the bracket (241) by an elastic element (222), which can be any kind of spring or elastic band. When the flexible PCB board is fixed by the spring element, the elastic shielding diaphragm will not change the structure of the eddy current detection sensor coil due to elastic deformation when it is pushed towards the detection surface, thereby avoiding changes in the detection parameters due to changes in the coil spacing of the eddy current detection sensor.

[0020] Furthermore, the eddy current testing instrument (3) is a multi-channel eddy current testing instrument, with several micro-holes (231) arranged in an array on the elastic shielding membrane (23) to form a multi-channel detection of defect information at different micro-region locations. The eddy current testing sensor (221) is an array of planar spiral coils or a single planar spiral coil, a circular or square coil, with multiple micro-hole windows corresponding to the coil. The detection signals from multiple channels are collected into image information. The multi-channel eddy current testing instrument can extract the detection signals of each sensor in the array of detection sensors and splice them together to form a detection image display at the specific detection signal position. Alternatively, it can splice the detection signals from different positions of the micro-hole windows of a single eddy current testing sensor into an image. Multiple micro-hole windows detect the detection signals at each position in a time sequence and splice them together to form a specific location image of a micro-region. Just as a fine pen can draw a more accurate image, only when the sensor diameter is small enough can a detailed and accurate defect information image within a micro-region be formed.

[0021] Furthermore, the micropores (231) provided on the elastic shielding film (23) are either circular or square, and are arranged in an array on the detection surface of the PCB board on which the eddy current detection sensor is provided. Depending on the shape requirements of the micro-area, different micropore shapes can be selected to be manufactured, and a single eddy current detection sensor or multiple arrayed eddy current detection sensors arranged in an array on the PCB board can form a multi-channel micropore precision window.

[0022] Based on the above technical solution, the present invention has the following beneficial effects: The present invention employs micro-pores in an elastic shielding film, combined with conventional single, dual, or array eddy current sensor probes. It utilizes the micro-area scanning within the effective detection range of the eddy current probe coil using the elastic shielding film. The acquired eddy current scanning signals are then processed, specifically by weighting and "zeroing" the signals obtained from scanning defect-free micro-areas. When micro-cracks or discontinuities exist within the micro-area, particularly cracks at the edge of the orifice in a eddy current engine blade, eddy current imaging will display the shape of the orifice and defects at its edge. The present invention, through the array of micro-pores in the elastic shielding film, uses eddy current mechanical XY scanning imaging and the eddy current detection signal passing through the orifice in the eddy current engine blade to image the micro-area of ​​interest, thus achieving image processing for micro-area detection. Attached Figure Description

[0023] Figure 1 This is a schematic diagram showing the detection device in use according to the preferred embodiment of the present invention.

[0024] Figure 2 This is a schematic diagram of the detection device structure according to the preferred embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the detection state structure of the detection device according to the preferred embodiment of the present invention;

[0026] Figure 4 A magnified schematic diagram (AA) of the detection device structure according to the preferred embodiment of the present invention;

[0027] Figure 5 This is a schematic diagram of the detection device structure according to the preferred embodiment of the present invention;

[0028] Figure 6 This is a schematic diagram of the detection state structure of the detection device according to the preferred embodiment of the present invention;

[0029] Figure 7 This is a schematic diagram of the detection sensor structure according to the preferred embodiment of the present invention;

[0030] Figure 8 This is a schematic diagram of the detection sensor structure according to the preferred embodiment of the present invention;

[0031] Figure 9 This is a schematic diagram of the elastic shielding membrane structure of the preferred embodiment of the present invention;

[0032] Figure 10 This is a schematic diagram of the detection device structure according to the preferred embodiment of the present invention;

[0033] Figure 11 This is a schematic diagram of the detection state structure of the detection device according to the preferred embodiment of the present invention;

[0034] Figure 12This is a schematic diagram of the detection state structure of the detection device according to the preferred embodiment of the present invention;

[0035] Figure 13 This is a schematic diagram of the detection sensor and the microporous structure of the elastic shielding film according to the preferred embodiment of the present invention;

[0036] Figure 14 This is a schematic diagram of the detection sensor and the spreading device according to the preferred embodiment of the present invention;

[0037] Figure 15 A schematic diagram of the detection sensor and another elastic shielding membrane microporous structure of the preferred embodiment of the present invention;

[0038] Figure 16 This is a schematic diagram of eddy current detection imaging, which is the preferred embodiment of the present invention. Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0040] like Figures 1 to 9 As shown, a micro-area precision eddy current detection method is used for non-destructive eddy current detection of tiny holes 11 of varying shapes on rotor blades 1 of an aero-turbine engine. This method involves setting a layer of elastic shielding film with micropores on the detection surface of an eddy current detection sensor on a flexible PCB board. The micropores on the elastic shielding film are elastically expanded, thereby forming a micro-pore detection window area on the detection surface of the eddy current detection sensor on the flexible PCB board. This achieves non-destructive eddy current detection of tiny areas. The specific steps are as follows:

[0041] a. Aperture parameter preset: Based on the surface shape and structure requirements of the object being tested, such as pores and cracks, the required micropore window area for eddy current testing is evaluated and calculated.

[0042] b. Micropore adjustment setting: By pushing and pulling the elastic shielding film, it is elastically deformed towards the detection surface. The elastic deformation opens micropores placed on the elastic shielding film, and the adjustment forms a pore-type detection window;

[0043] c. Actual inspection: The eddy current detection sensor on the flexible PCB board detects the defect information of the object being inspected through the micropores on the elastic shielding film;

[0044] d. Detection Data Analysis: Acquire signal data from eddy current sensors corresponding to the micropores of the expanded elastic shielding membrane, and evaluate the defect parameters at the precise locations of the micropores. This can be achieved through imaging analysis and other methods to realize precise eddy current detection, evaluation, and analysis of minute areas.

[0045] like Figure 2The microporous elastic shielding film 23 shown is a diaphragm-type electromagnetic shielding layer made of an elastic conductive material. Tiny pores are set in the film layer. When the elastic shielding film is in a normal state, the elastic contraction of the micropores almost fills the micropore gaps, eliminating the micropore gaps and creating a continuous electromagnetic seal. No electromagnetic wave leakage will occur. That is, the eddy current detection sensor 221 on the flexible PCB board 22 is shielded and isolated from the device being tested, and no detection signal is generated.

[0046] like Figure 3 and Figure 4 As shown, when the elastic shielding film 23 is elastically stretched to a certain deformation, the micropore 231 overcomes the elastic force of the elastic film to form a gap. When the gap reaches a certain aperture, electromagnetic leakage is formed. The electromagnetic signal of the eddy current detection sensor 221 on the flexible PCB board 22 passes through the micropore to form an electromagnetic detection signal in a small area.

[0047] like Figure 10 , 11 and Figure 12 As shown, the adjustment settings for the micropores 231 also include adjusting the different diameters of the micropores in the elastic shielding membrane by adjusting the degree of stretching deformation of the elastic shielding membrane 23, thereby adjusting the actual area of ​​the tiny region in eddy current nondestructive testing. Figure 11 and Figure 12 In the process, different stretching procedures of the elastic shielding film 23 result in different pore sizes of the micropores 231 formed. Figure 12 The pore size of micropore 231 in the middle is larger than Figure 11 The aperture formed in the elastic shielding film is determined by the extent to which the elastic shielding film 23 is pushed towards the detection surface. This results in a greater degree of tensile elastic deformation, a larger gap created by the expansion of the micropores, and a relatively larger detection micropore window formed on the elastic shielding film by the eddy current detection sensor coil on the flexible PCB board 22. For example, the rotor blades of aero-turbine engines have numerous tiny holes with diameters of 0.1–0.8 mm and depths exceeding 3 mm. Since conventional eddy current detection sensor coils can only achieve a minimum diameter of 0.8 mm, they cannot accurately detect defects such as tiny cracks within such a small area, especially those around the blade holes. This invention utilizes the micropores formed by the elastic shielding film. The aperture size of the micropores is adjusted according to the needs of the blade holes, and the shielding film is aligned with the tiny area, enabling precise detection of defects such as tiny holes on aero-turbine engine rotor blades, particularly small cracks around the blade holes. This allows for the detection of defects before the small cracks expand and affect the airflow of the aero-engine, thus enabling early detection of potential safety hazards.

[0048] like Figure 10As shown, this also includes using a fixed-threaded helical push rod to push the flexible PCB board away from the detection surface, thereby stretching the elastic shielding film, elastically opening the micropores, and adjusting the micropore diameter. The fixed thread, i.e., the pitch, is a fixed value; the vertical movement distance during rotation adjustment is also a fixed value. Furthermore, the specific aperture parameter value required by the object being tested can be used to calibrate a quantitative value for the fixed thread pitch, thereby adjusting the micropore diameter by adjusting the quantitative value of the pitch.

[0049] like Figure 5 , Figure 6 , Figure 7 and Figure 8 As shown, the eddy current detection sensor for the flexible PCB board is an array-type planar spiral coil sensor. Each coil detects and acquires detection information corresponding to a micro-hole on the elastic shielding diaphragm. Figure 7 and Figure 8 As shown in the figure, an array of planar spiral coils is arranged on a flexible PCB board, with each coil corresponding to a micro-hole detection window, enabling large-area scanning and detection. The planar spiral coils can be as follows: Figure 7 The circle shown or as Figure 8 The square shown.

[0050] like Figure 2 and Figure 3 ,as well as Figure 13 and Figure 14 As shown, the eddy current detection sensor on the flexible PCB is a single planar spiral coil sensor. The planar spiral coil corresponds to several micro-holes 231 set on the elastic shielding diaphragm. The eddy current detection coil sequentially acquires detection information of the area corresponding to the micro-holes. Figure 14 As shown, the spreading device 24 pushes the single planar spiral coil of the eddy current detection sensor on the flexible PCB board 22 to attach to the corresponding multiple micro-holes 231, and detects each micro-hole in turn by spreading the elastic shielding film. The multi-channel eddy current detector obtains the detection information on each micro-hole 231 in a time sequence, which is more suitable for the one-time detection needs of dense micro-areas.

[0051] like Figures 10 to 12As shown, the present invention also discloses a micro-area precision eddy current detection device for non-destructive testing of eddy currents in tiny holes 11 of varying shapes on rotor blades 1 of an aero-turbine engine. The detection device 2 is connected to a multi-channel eddy current testing instrument and includes an eddy current testing instrument 3, a probe housing 21, and a flexible PCB board 22. The flexible PCB board is fixed inside the probe housing 21 at the end near the detection surface. An eddy current detection sensor 221 is disposed on the flexible PCB board 22. An elastic shielding film 23 is disposed on the side of the flexible PCB board 22 near the object being tested, and a spreading device 24 is disposed on the side away from the object being tested. The elastic shielding film 23 has micropores 231. When the spreading device 24 pushes the flexible PCB board 22 toward the detection surface, the elastic shielding film 23 elastically deforms and spreads the micropores 231 to form an eddy current detection window.

[0052] like Figure 11 and Figure 12 As shown, the spreading device 24 also includes a bracket 241. A flexible PCB board 21 is elastically fixed to the bracket 241. The bracket 241 is rotatably connected to the inner side of the probe housing 21 via a fixing thread 242. Pushing the push rod 243 fixed to the bracket 241 allows it to move up and down. Figure 10 As shown, the flexible PCB board 22 can be elastically fixed to the bracket 241 by an elastic element 222. The elastic element can be any type such as a spring or an elastic band. When the flexible PCB board is fixed by the spring element, the elastic shielding diaphragm will not change the structure of the eddy current detection sensor coil due to elastic deformation when it is pushed toward the detection surface, thereby avoiding changes in the detection parameters due to changes in the coil spacing of the eddy current detection sensor.

[0053] like Figure 13 As shown, the eddy current testing instrument 3 is a multi-channel eddy current testing instrument. Several micro-holes 231 are arrayed and arranged on the elastic shielding membrane 23, forming a multi-channel detection system to capture defect information at different micro-region locations. The eddy current sensor 221 is an array of planar spiral coils or a single planar spiral coil, a circular or square coil, with multiple micro-hole windows corresponding to the coil. The multi-channel detection signals are collected to form image information. The multi-channel eddy current testing instrument can extract the detection signals from each sensor in the array of sensors and stitch them together to form a detection image display at the specific detection signal location. Alternatively, it can stitch together the detection signals from different micro-hole windows of a single eddy current sensor to form an image. Multiple micro-hole windows sequentially detect the detection signals at each location, stitching them together to form a specific location image of a micro-region. This is analogous to the principle that a fine enough pen can draw a more precise image; only when the sensor diameter is small enough can a detailed and accurate defect information image within a micro-region be formed. Figure 16The detection image shown can only detect the fine cracks 12 at the edge of the small hole 11 if the diameter of the eddy current detection sensor is smaller than the small hole 11 in the turbine rotor blade. If the diameter of the eddy current detection sensor 22 is too large and completely covers the small hole, it can only show that there is a defect signal in a large area covered by the sensor, but cannot accurately detect the specific shape and location of the defect.

[0054] like Figure 13 and Figure 15 As shown, the micropores 231 on the elastic shielding film 23 are either circular or square, and are arranged in an array on the detection surface of the PCB board on which the eddy current detection sensor is located. Depending on the shape requirements of the micro-area, different micropore shapes can be selected to be manufactured, and a single eddy current detection sensor or multiple arrayed eddy current detection sensors arranged in an array on the PCB board can form a multi-channel micropore precision window.

[0055] The above is one embodiment of the present invention. Furthermore, it should be noted that any equivalent or simple variations made to the structure, features, and principles described in this patent concept are included within the scope of protection of this patent.

Claims

1. A method for precise eddy current detection in a micro-area, characterized in that... A technique for non-destructive eddy current testing in micro-regions is developed by setting a microporous elastic shielding film on the detection surface of an eddy current sensor on a flexible PCB board. The micropores on the elastic shielding film are elastically expanded, thereby forming a micro-pore detection window area on the detection surface of the eddy current sensor on the flexible PCB board. The microporous elastic shielding film is a film-type electromagnetic shielding layer made of an elastic conductive material. The film has tiny pores. When the elastic shielding film is in a normal state, the elastic contraction of the micropores almost fills the micropore gaps, eliminating the micropore gaps and creating a continuous electromagnetic seal. No electromagnetic wave leakage occurs. That is, the eddy current sensor on the flexible PCB board and the device under test are shielded and isolated, and no detection signal is generated. When the elastic shielding film is stretched to a certain deformation, the micropores overcome the elastic force of the film to form gaps. When the gaps reach a certain aperture, electromagnetic leakage occurs. The electromagnetic signal from the eddy current detection sensor on the flexible PCB board passes through the micropores, forming an electromagnetic detection signal in a tiny area. The specific steps are as follows: a. Preset aperture parameters: Based on the specific shape and structure of the surface of the object being tested, evaluate and calculate the area of ​​the micropore window required for the eddy current testing surface; b. Micropore adjustment setting: By pushing and pulling the elastic shielding film, it is elastically deformed towards the detection surface. The elastic deformation opens micropores placed on the elastic shielding film, and the adjustment forms a pore-type detection window; c. Actual testing: The eddy current testing sensor on the flexible PCB board detects the defect information of the object being tested through the micropores on the elastic shielding film; d. Detection data analysis: Obtain the signal data detected by the eddy current detection sensor corresponding to the micropores of the stretched elastic shielding membrane, and evaluate the defect parameters at the precise location of the micropores.

2. The method for precise micro-area eddy current detection according to claim 1, characterized in that... The micropore adjustment setting also includes adjusting the diameter of the micropores in the elastic shielding membrane by adjusting the degree of stretching deformation of the elastic shielding membrane, thereby adjusting the actual area of ​​the small region in eddy current nondestructive testing.

3. The method for precise micro-area eddy current detection according to claim 2, characterized in that... It also includes using a fixed threaded structure to move a helical push rod to push the flexible PCB board away from the detection surface, thereby pushing and stretching the elastic shielding film, elastically opening the micropores, and adjusting the pore size of the micropores.

4. The method for precise micro-area eddy current detection according to claim 3, characterized in that... It also includes calibrating the fixed thread pitch value by using the specific aperture parameter value required by the object being tested, thereby adjusting the aperture of the micro-hole by adjusting the pitch value.

5. The method for precise eddy current detection in a micro-area according to claim 1, characterized in that... The flexible PCB board eddy current detection sensor is an array-type eddy current detection planar spiral coil sensor, where each coil detects and acquires detection information corresponding to a micro-hole on an elastic shielding diaphragm.

6. The method for precise eddy current detection in a micro-area according to claim 1, characterized in that... The flexible PCB board eddy current detection sensor is a planar spiral coil sensor. The planar spiral coil corresponds to several micro-holes set on the elastic shielding film. The eddy current detection coil detects and acquires detection information of the area corresponding to the micro-holes in turn.

7. A micro-area precision eddy current detection device, comprising an eddy current detection instrument (3), a probe housing (21), and a flexible PCB board (22), wherein the flexible PCB board is fixed inside the probe housing (21) near the end of the detection surface, and an eddy current detection sensor (221) is disposed on the flexible PCB board (22); characterized in that The flexible PCB board (22) has an elastic shielding film (23) on the side close to the object being tested, and an opening device (24) on the side away from the object being tested; The elastic shielding film (23) is provided with micropores (231). When the spreading device (24) pushes the flexible PCB board (22) toward the detection surface, the elastic shielding film (23) elastically deforms and spreads the micropores (231) to form an eddy current detection window. The microporous elastic shielding film is a membrane electromagnetic shielding layer made of an elastic conductive material. Tiny pores are set in the film layer. When the elastic shielding film is in a normal state, the elastic contraction of the micropores almost fills the micropore gaps, eliminating the micropore gaps and creating a continuous electromagnetic seal. No electromagnetic wave leakage will occur. That is, the eddy current detection sensor on the flexible PCB board and the device under test are shielded and isolated, and no detection signal is generated. When the elastic shielding film is stretched to a certain deformation, the micropores overcome the elastic force of the elastic film to form gaps. When the gaps reach a certain aperture, electromagnetic leakage occurs. The electromagnetic signal of the eddy current detection sensor on the flexible PCB board passes through the micropores to form electromagnetic detection signals in a tiny area.

8. A micro-area precision eddy current detection device according to claim 7, characterized in that... The opening device (24) further includes a bracket (241), the flexible PCB board (22) is elastically fixed to the bracket (241), the bracket (241) is fixed by a thread (242) and rotatedly connected to the inside of the probe housing (21), and the push rod (243) fixed on the bracket (241) can be moved up and down.

9. A micro-area precision eddy current detection device according to claim 7, characterized in that... The eddy current testing instrument (3) is a multi-channel eddy current testing instrument, with a number of micro-holes (231) arranged in an array on the elastic shielding membrane (23) to form a multi-channel detection of defect information in different micro-regions.

10. A micro-area precision eddy current detection device according to claim 7, characterized in that... The micropores (231) provided on the elastic shielding film (23) are either circular or square, and are arranged in an array on the detection surface of the PCB board on which the eddy current detection sensor is provided.

Images