CN113433212B - Uniform field excitation directional eddy current probe with high interference resistance and detection method - Google Patents
Uniform field excitation directional eddy current probe with high interference resistance and detection method Download PDFInfo
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- CN113433212B CN113433212B CN202110706287.XA CN202110706287A CN113433212B CN 113433212 B CN113433212 B CN 113433212B CN 202110706287 A CN202110706287 A CN 202110706287A CN 113433212 B CN113433212 B CN 113433212B
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
- G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws
- G01N27/90—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
- G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws
- G01N27/90—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents
- G01N27/9006—Details, e.g. in the structure or functioning of sensors
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
- G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws
- G01N27/90—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents
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- G01N27/902—Arrangements for scanning by moving the sensors
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Abstract
The probe comprises an excitation part and a detection part, wherein the excitation part is uniformly wound by a rectangular framework and a plurality of turns of wires to form a rectangular excitation coil; the detection part consists of two disc-type small coils with axes perpendicular to the normal direction of the metal member to be detected and the same winding direction, and the middle wires on the lower surface of the rectangular exciting coil are symmetrically distributed by taking the middle wires as symmetry axes. During detection, excitation signals are introduced into the rectangular excitation coil, and a relatively uniform vortex field is induced by the metal component to be detected below the coil; since the rectangular excitation coil is large enough, the detection signals of the two detection coils are approximately the same when no defect exists; when the detection device is defective, the defect can generate disturbance to the uniform vortex field, and the differential signals of the two small coils are taken as target signals, so that on one hand, the detection sensitivity can be enhanced, and meanwhile, the influence of lift-off noise can be effectively reduced. And by rotating the probe, analyzing the relation between the scanning direction and the scanning signal, and realizing the directional identification of the defects.
Description
Technical Field
The invention relates to an electromagnetic nondestructive testing probe, in particular to a high-sensitivity anti-interference directional uniform field excitation differential output eddy current probe and a testing method.
Background
The metal components are used in a variety of applications, such as in the fields of aerospace, additive manufacturing, nuclear power, and the like. Under the extreme service condition, the metal component inevitably generates defects such as micro cracks, residual stress and the like, so that the component is damaged and fails, and serious industrial accidents are caused. Therefore, periodic nondestructive evaluation of such defects is indispensable.
The eddy current detection method is a nondestructive detection method based on the electromagnetic induction principle, and has the advantages of non-contact, no need of coupling medium, high detection speed, easy realization of automatic detection, high detection sensitivity to surface and near-surface defects and the like. In crack detection of a metal component, a disk-type small coil with a magnetic core is often adopted as a traditional eddy current probe, and the probe is a pen-type eddy current probe, so that the overall size of the probe is smaller, and the detection spatial resolution and the sensitivity are higher. However, the probe generally adopts a self-excitation self-detection mode, so that the probe has larger detection noise, such as lift-off noise, inclination noise and the like, namely the probe has weak anti-interference capability and poor robustness. In addition, the disk-type small coil is of a circular axisymmetric structure, so that the directional identification of the defects cannot be realized.
In order to solve the problems that the traditional disc coil probe is easy to be interfered by noise, poor in robustness, incapable of detecting the defect direction and the like, the invention designs the uniform field excitation directional eddy current probe with high interference resistance.
Disclosure of Invention
In order to solve the problems in the prior art, the invention aims to provide a uniform field excitation directional eddy current probe with high interference resistance and a detection method. The probe can effectively enhance the defect detection sensitivity, weaken the influence of lift-off noise, and effectively identify the direction of the defect.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the uniform field excitation directional eddy current probe with strong interference resistance is an external eddy current detection probe, and is arranged on the surface of the metal member 1 to be detected for scanning detection; the device comprises an excitation part and a detection part, wherein the excitation part is a rectangular excitation coil and comprises a large rectangular framework 2 and a plurality of turns of wires 4 uniformly wound on the large rectangular framework; the detection part is two small disk-shaped coils 3 which are positioned right below the rectangular exciting coils.
The detection part is a differential detection unit and consists of two disc-type small coils 3 with axes perpendicular to the normal direction of the metal member 1 to be detected; the center wire of the lower surface of the rectangular exciting coil is used as a symmetry axis, the two small disc-shaped coils are symmetrically distributed on the lower surface of the rectangular exciting coil, the position of the small disc-shaped coils is the center of the lower surface of the rectangular exciting coil, and a lifting distance is reserved between the small disc-shaped coils and the rectangular exciting coil.
The wire winding direction of the two disc-shaped small coils 3 of the detection part is the same.
The detection section finally detects signals as differential signals of the two small disc coils 3.
The size of the rectangular exciting coil is at least 1 order of magnitude larger than that of the two small disc coils 3, so that the two small disc coils are in a relatively uniform exciting magnetic field, the axial directions of the two small disc coils 3 are consistent with the axial directions of the rectangular exciting coil, on one hand, the detection sensitivity of the probe to defects is improved, on the other hand, the influence of lift-off noise is effectively weakened, and the anti-interference capability of the probe to noise is improved.
The detection method of the uniform field excitation directional eddy current probe with strong interference resistance,
firstly, a steady-state sinusoidal excitation current is introduced into a rectangular excitation coil, the steady-state sinusoidal excitation current can generate an alternating magnetic field, namely a direct magnetic field, and a metal component 1 to be detected placed in the alternating magnetic field can generate a relatively uniform vortex field; the alternating vortex field can generate a secondary magnetic field, and the composite magnetic field obtained by superposition of the direct magnetic field and the secondary magnetic field can enable two ends of the two small disc coils 3 to generate voltage signals; the secondary magnetic field induced by the influence of the defects of different forms and different sizes of the metal member 1 to be detected also generates corresponding changes, so that different voltage signals are generated in the two small disc coils 3;
secondly, the size of the rectangular exciting coil is designed to be large enough relative to the disc-shaped small coil 3 of the detection part, so that the two disc-shaped small coils can be in a relatively uniform magnetic field, and the differential signals of the two disc-shaped small coils 3 are taken as final detection signals; when the uniform vortex field area is free of defects, the detection signals of the two small disk coils 3 are the same, and the final detection differential signal is supposed to be 0 in principle; when the uniform vortex field area has defects, the defects can generate disturbance on the uniform vortex field, and the final detected differential signal can be disturbed; in addition, as the axial directions of the two small disc-shaped coils are consistent with the axial directions of the rectangular exciting coils, the passing rate of the secondary magnetic field to the detecting coils is enhanced;
finally, the rectangular exciting coil of the exciting part and the two small coils 3 of the detecting part are integrated, and are arranged on the surface of the metal member 1 to be detected for scanning; comparing the detected signal with the detected signal of the non-defective member to judge whether the current scanning area has a defect; if the defect exists, repeatedly scanning the region of the metal member to be detected, finally determining the position of the defect, and further analyzing and evaluating the size of the defect by combining with signal processing;
meanwhile, by utilizing the characteristic that the eddy current induced by the rectangular exciting coil in the metal member 1 to be detected has directivity, the relation between the scanning direction and the scanning signal is analyzed by rotating the probe, and the defect direction is effectively identified.
Compared with the prior art, the invention has the following advantages:
the invention relates to a uniform field excitation directional eddy current probe with strong anti-interference, and a rectangular excitation coil generates a relatively uniform eddy current field in a metal member, so that the influence of lift-off noise can be effectively weakened, and the anti-interference capability of the probe on the noise is improved. The detection part consists of two small disc coils with axes perpendicular to the normal direction of the metal member to be detected, and the arrangement method enhances the passing rate of the secondary magnetic field to the detection coil and effectively enhances the detection signal and the detection sensitivity; the wires of the two small disc coils have the same winding direction, so that signal analysis and processing are easier to perform; after the detected signals of the two small coils have the same noise difference, the noise can be weakened.
Drawings
FIG. 1 is a schematic illustration of the placement of a probe and a metallic component to be tested according to the present invention.
FIG. 2 is a schematic diagram of the co-operation of the probe of the present invention with an eddy current inspection system.
Fig. 3 is a schematic structural view of the exciting coil part of the present invention.
FIG. 4 is a schematic diagram of the structure of the detecting coil portion of the present invention.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings and specific examples.
As shown in fig. 1, in this embodiment, an eddy current probe for metal member defect is an external eddy current probe, which is placed on the surface of a metal member 1 to be tested for scanning detection and named as a uniform field excitation directional eddy current probe with strong anti-interference. The external eddy current probe includes an excitation portion and a detection portion. During detection, the excitation part and the detection part are integrated, wherein the detection part needs to be close to the metal member 1 to be detected and the excitation coil, so that the lifting-off is smaller, the intensity of the vortex field is larger, and the detection coil can pick up more defect signals. The excitation part is a rectangular excitation coil and comprises a large rectangular framework 2 and a plurality of turns of wires 4 uniformly wound on the large rectangular framework; the detection part is a differential detection unit and consists of two small disc coils 3 with axes perpendicular to the normal direction of the metal member 1 to be detected. The center wire of the lower surface of the rectangular exciting coil is used as a symmetry axis, the two small disc-shaped coils 3 are symmetrically distributed on the lower surface of the rectangular exciting coil, the position of the small disc-shaped coils is the center of the lower surface of the rectangular exciting coil, and a certain lifting distance is reserved between the small disc-shaped coils and the rectangular exciting coil.
As shown in fig. 2, the flow of the uniform field excitation directional eddy current probe detection system with strong interference resistance is as follows: generating a steady-state sinusoidal excitation current by a signal generator; flowing a steady-state sinusoidal excitation current through a power amplifier to increase the power of the excitation current; then connecting the amplified steady-state sinusoidal excitation current with a rectangular excitation coil; the two small coils 3 receive voltage signals containing defect information of the detected components, and the detected signals are preprocessed by a differential amplifier and a lock-in amplifier and transmitted to a signal acquisition and display system for signal analysis and processing.
As shown in fig. 3, the exciting portion is a rectangular coil, and comprises a large rectangular framework 2, wherein a plurality of turns of wires 4 are uniformly wound on the large rectangular framework 2, and the wire bundles of each layer and the wire bundles between the layers are tightly and uniformly distributed.
As shown in fig. 4, the detecting section is a differential detecting unit composed of two small disc-shaped coils 3 whose axes are the same as those of the rectangular exciting coil. The center wire of the lower surface of the rectangular exciting coil is used as a symmetry axis, the two small disc-shaped coils are symmetrically distributed on the lower surface of the rectangular exciting coil, the position of the small disc-shaped coils is the center of the lower surface of the rectangular exciting coil, and a certain lifting distance is reserved between the small disc-shaped coils and the rectangular exciting coil. The axial directions of the two small disc coils 3 are consistent with the axial directions of the rectangular exciting coils, and the winding directions of the leads of the two small disc coils 3 are the same, so that the analysis and the treatment of defect signals are facilitated.
The working principle of the invention is as follows: the invention aims to realize detection and evaluation of microcracks or residual stress of a metal component to be detected.
Firstly, a steady-state sinusoidal excitation current is supplied to a rectangular excitation coil, which generates an alternating magnetic field (direct magnetic field) in which the metal component 1 to be measured generates a relatively uniform eddy current field. The alternating vortex field can generate a secondary magnetic field, and the composite magnetic field obtained by superposition of the direct magnetic field and the secondary magnetic field can enable the two ends of the two small disc coils 3 to generate voltage signals. The secondary magnetic field induced will also change correspondingly due to the influence of the defects of different forms and different sizes of the metal member 1 to be tested, so that different voltage signals are generated in the two small disc coils 3.
Secondly, the size of the excitation coil is designed to be large enough relative to the disc-shaped small coil 3 of the detection section so that the two disc-shaped small coils can be placed in a relatively uniform magnetic field, taking the differential signal of the two disc-shaped small coils 3 as the final detection signal. When the uniform vortex field area is free of defects, the detection signals of the two small disk coils 3 are the same, and the final detection differential signal is supposed to be 0 in principle; when the uniform vortex field area has defects, the defects can generate disturbance on the uniform vortex field, and the final detected differential signal can be disturbed. In addition, the axial direction of the two small disc coils is consistent with the axial direction of the rectangular exciting coil through design, so that the passing rate of the secondary magnetic field to the detecting coil is enhanced. Through the series of designs, on one hand, the detection sensitivity of the probe to the defects can be improved, and on the other hand, the influence of lift-off noise can be effectively weakened, and the anti-interference capability of the probe to the noise is improved.
Finally, the rectangular coil of the excitation part and the two small coils 3 of the detection part are integrated, and are placed on the surface of the metal member 1 to be detected for scanning. The probe firstly scans on a non-defective metal member to obtain a non-defective signal, then scans on a member to be detected to obtain a detected signal, compares the detected signal with the non-defective signal, and judges whether a defect exists in a current scanning area. If the defect exists, the position of the defect can be finally determined by repeatedly scanning the region of the metal member to be detected, and the size of the defect can be further evaluated by combining signal processing analysis.
Meanwhile, by utilizing the characteristic that the eddy current induced by the rectangular exciting coil in the metal member 1 to be detected has directivity, the relation between the scanning direction and the scanning signal can be analyzed through the rotating probe, and the defect direction can be effectively identified.
Claims (3)
1. The directional eddy current probe is excited by a uniform field with strong anti-interference, and is characterized in that: the probe is an external eddy current detection probe, and is arranged on the surface of a metal component (1) to be detected for scanning detection; the device comprises an excitation part and a detection part, wherein the excitation part is a rectangular excitation coil and comprises a large rectangular framework (2) and a plurality of turns of wires (4) uniformly wound on the large rectangular framework; the detection part is two small disc coils (3) which are positioned right below the rectangular exciting coils;
the detection part is a differential detection unit and consists of two small disc coils (3) with axes perpendicular to the normal direction of the metal member (1) to be detected; the center wire of the lower surface of the rectangular exciting coil is used as a symmetry axis, two small disc coils are symmetrically distributed on the lower surface of the rectangular exciting coil, the position of the small disc coils is the center of the lower surface of the rectangular exciting coil, and a lifting distance is reserved between the small disc coils and the rectangular exciting coil;
the size of the rectangular exciting coil is at least 1 order of magnitude larger than that of the two small disc coils (3), so that the two small disc coils are in a relatively uniform exciting magnetic field, the axial directions of the two small disc coils (3) are consistent with the axial directions of the rectangular exciting coil, on one hand, the detection sensitivity of the probe to defects is improved, on the other hand, the influence of lift-off noise is effectively weakened, and the anti-interference capability of the probe to noise is improved;
the detection method of the uniform field excitation directional eddy current probe with strong interference resistance,
firstly, a steady-state sinusoidal excitation current is introduced into a rectangular excitation coil, the steady-state sinusoidal excitation current can generate an alternating magnetic field, namely a direct magnetic field, and a metal component (1) to be detected in the alternating magnetic field can generate a relatively uniform vortex field; the alternating vortex field can generate a secondary magnetic field, and the composite magnetic field obtained by superposition of the direct magnetic field and the secondary magnetic field can enable two ends of the two small disc coils (3) to generate voltage signals; the secondary magnetic field induced by the influence of the defects of different forms and different sizes of the metal component (1) to be detected also generates corresponding changes, so that different voltage signals are generated in the two small disc coils (3);
secondly, the size of the rectangular exciting coil is designed to be large enough relative to the disc-shaped small coil (3) of the detection part, so that the two disc-shaped small coils can be in a relatively uniform magnetic field, and the differential signals of the two disc-shaped small coils (3) are taken as final detection signals; when the uniform vortex field area is free of defects, the detected signals of the two small disk coils (3) are the same, and the final detected differential signal is supposed to be 0 in principle; when the uniform vortex field area has defects, the defects can generate disturbance on the uniform vortex field, and the final detected differential signal can be disturbed; in addition, as the axial directions of the two small disc-shaped coils are consistent with the axial directions of the rectangular exciting coils, the passing rate of the secondary magnetic field to the detecting coils is enhanced;
finally, the rectangular exciting coil of the exciting part and the two small coils (3) of the detecting part are integrated, and are arranged on the surface of the metal member (1) to be detected for scanning; comparing the detected signal with the detected signal of the non-defective member to judge whether the current scanning area has a defect; if the defect exists, repeatedly scanning the region of the metal member to be detected, finally determining the position of the defect, and further analyzing and evaluating the size of the defect by combining with signal processing;
meanwhile, by utilizing the characteristic that eddy currents induced by the rectangular exciting coil in the metal component (1) to be detected have directivity, the relation between the scanning direction and the scanning signal is analyzed through the rotating probe, and the defect direction is effectively identified.
2. The high interference resistance uniform field excitation directional eddy current probe according to claim 1, wherein: the wire winding directions of the two small disc coils (3) of the detection part are the same.
3. The high interference resistance uniform field excitation directional eddy current probe according to claim 1, wherein: the detection part finally detects that the signal is a differential signal of two small coils (3).
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| CN114720556A (en) * | 2022-03-30 | 2022-07-08 | 中国民航大学 | Flat-cut sensor probe for CFRP laminated board defect detection and scanning detection method |
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| JPH01123143A (en) * | 1987-11-09 | 1989-05-16 | Nippon Nuclear Fuel Dev Co Ltd | Method and apparatus for detection of flaw by eddy current |
| JPH1164293A (en) * | 1997-08-19 | 1999-03-05 | Koji Otsuka | Method for magnetically non-destructively inspecting crack of concrete |
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| US4191922A (en) * | 1978-03-14 | 1980-03-04 | Republic Steel Corporation | Electromagnetic flaw detection system and method incorporating improved automatic coil error signal compensation |
| DE59711048D1 (en) * | 1996-09-27 | 2004-01-08 | Karsten Lothar Feiste | Measuring method and measuring device for material characterization of semi-finished products and machine components |
| CN103235036B (en) * | 2013-04-12 | 2015-12-23 | 厦门艾帝尔电子科技有限公司 | Based on pick-up unit and the method for the differentiation inside and outside wall defect of electromagnetic detection signal |
| CN103645243B (en) * | 2013-11-28 | 2017-01-04 | 南京航空航天大学 | Electromagnetic nondestructive detection system for power transmission line |
| GB2527835B (en) * | 2014-07-03 | 2017-02-22 | Technical Software Consultants Ltd | Compensating element for alternating current field measurement probe |
| CN204255904U (en) * | 2014-10-31 | 2015-04-08 | 江南大学 | Based on the Pulsed Eddy Current Testing System of rectangle difference detector |
| CN104865310B (en) * | 2015-06-29 | 2018-10-26 | 中国矿业大学 | The Pulsed eddy current testing apparatus and method of gear and axial workpiece carburizing depth |
| CN110308200B (en) * | 2019-07-16 | 2022-11-04 | 南京航空航天大学 | Differential magnetic leakage and eddy current composite high-speed rail flaw detection method |
| CN111581814B (en) * | 2020-05-07 | 2021-11-02 | 南京航空航天大学 | Parameter design method of high-speed track defect detection system based on differential eddy current |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH01123143A (en) * | 1987-11-09 | 1989-05-16 | Nippon Nuclear Fuel Dev Co Ltd | Method and apparatus for detection of flaw by eddy current |
| JPH1164293A (en) * | 1997-08-19 | 1999-03-05 | Koji Otsuka | Method for magnetically non-destructively inspecting crack of concrete |
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