CN111812193B - Array eddy current probe for actively relieving electromagnetic coupling between adjacent coils - Google Patents
Array eddy current probe for actively relieving electromagnetic coupling between adjacent coils Download PDFInfo
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- CN111812193B CN111812193B CN202010679303.6A CN202010679303A CN111812193B CN 111812193 B CN111812193 B CN 111812193B CN 202010679303 A CN202010679303 A CN 202010679303A CN 111812193 B CN111812193 B CN 111812193B
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- 239000000523 sample Substances 0.000 title claims abstract description 47
- 230000008878 coupling Effects 0.000 title claims abstract description 13
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- 238000005859 coupling reaction Methods 0.000 title claims abstract description 13
- 238000001514 detection method Methods 0.000 claims abstract description 74
- 239000002184 metal Substances 0.000 claims abstract description 33
- 230000005284 excitation Effects 0.000 claims description 3
- 238000004804 winding Methods 0.000 claims description 2
- 230000007547 defect Effects 0.000 abstract description 6
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- 238000009659 non-destructive testing Methods 0.000 description 2
- 230000003313 weakening effect Effects 0.000 description 2
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
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Abstract
The invention provides an array eddy current probe for actively relieving electromagnetic coupling between adjacent coils, which mainly solves two defects that the conventional array eddy current probe adopts a shielding cover to passively shield the electromagnetic coupling: 1. the channel for detecting the heat exchange between the coil joule heat and the external convection in the cover is blocked, the coil temperature rise is easy to cause, and the temperature drift error is caused; 2. the volume of the probe is increased, and the spatial resolution of the probe is reduced. The technical proposal is as follows: two auxiliary coils coaxial with the detection coils are arranged outside the detection coils of the probe, and the magnetic field generated by the auxiliary coils weakens the external magnetic field generated by the detection coils, so that the magnetic field interference of the adjacent detection coils is reduced. The auxiliary coil is provided with the metal sliding sheet, the length and the number of turns of the auxiliary coil connected to the loading circuit can be changed by moving the sliding sheet, so that the attenuation degree of an external magnetic field is adjusted, and different requirements of different application scenes on the electromagnetic decoupling degree of the adjacent coil are met. Compared with the existing array eddy current probe, the probe provided by the invention has smaller volume and smaller temperature drift error.
Description
Technical Field
The invention belongs to the technical field of nondestructive testing, further belongs to the technical field of eddy current testing, in particular relates to an array eddy current probe for nondestructive testing, and particularly relates to an array eddy current probe without a shielding cover, which reduces electromagnetic coupling between adjacent detection coils.
Background
The eddy current detection is a nondestructive detection technology widely applied in the industrial field, and the working principle is based on the electromagnetic induction principle: when the detection coil with alternating current is close to the metal conductor, an alternating magnetic field is generated in the metal conductor and is called a primary magnetic field, and meanwhile, the alternating magnetic field induces eddy current on the surface of the metal conductor; the eddy currents in the metal conductor also generate a magnetic field, called the secondary magnetic field; if the surface of the metal conductor has defects such as cracks, the current vortex can be caused to change, the change is induced in the detection coil through a secondary magnetic field, and finally the change is characterized as the change of coil impedance, so that the existence and the severity of the defects on the surface of the metal conductor can be judged. The eddy current detection has the advantages of non-contact, high speed, high sensitivity to surface defects and the like. The single detection coil type eddy current probe has small coverage area, and the point-by-point scanning detection is carried out on a larger-area test piece, so that time and labor are wasted, and sometimes missed detection is possible. The array eddy current probe consists of a plurality of independent detection coils, and has the following advantages compared with a single detection coil type probe: the probe coverage area is large, and the detection efficiency is high; the appearance design can be carried out according to the size and the shape surface of the tested test piece, and a mechanical scanning device with complex design and manufacture is not needed. However, there is electromagnetic coupling between adjacent detection coils, and the resulting detection coil impedance change is superimposed on the impedance change caused by the defect, resulting in a deviation of the detection result. In order to solve this problem, a method of providing an electromagnetic shield outside the detection coil is currently used. However, the closed shielding cover structure can obstruct heat exchange of the electrified coil in the cover, so that the coil is easy to overheat, and the precision and the service life of the coil are affected; second, the introduction of a shield can increase the volume of the probe, resulting in a low spatial resolution of the probe. Therefore, it is necessary to provide an array eddy current probe which can remove the electromagnetic coupling effect between the detection coils without adding a shield structure.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide an array eddy current probe capable of actively relieving electromagnetic coupling between adjacent coils, which has the following advantages: a shielding cover is not required to be added outside the detection coil, so that the joule heat of the detection coil is conveniently dissipated in time so as not to cause overheat; the volume of the probe is reduced, and the spatial resolution is improved.
The technical scheme adopted for solving the technical problems is as follows: removing the shielding cover, and arranging two solenoid coils which are coaxial with the detection coils and are respectively positioned at two end parts of the detection coils outside the detection coils as auxiliary coils; the magnetic field generated by the auxiliary coil weakens the external magnetic field generated by the detection coil and distributed in the radial direction, so that the magnetic field interference between the adjacent detection coils is reduced; the varistor type metal sliding sheet is arranged on the auxiliary coil, one terminal of the metal sliding sheet and the auxiliary coil is connected into the loading circuit of the auxiliary coil, so that the length and the number of turns of the auxiliary coil connected into the loading circuit can be changed by moving the metal sliding sheet, and the weakening degree of the auxiliary coil magnetic field to the detection coil magnetic field is adjusted, so that different requirements of different application scenes on the electromagnetic decoupling degree between the detection coils are met.
The technical effects of the invention are as follows: (a) A shielding cover structure is not required to be arranged outside the probe detection coil, so that joule heat generated by the probe during operation is timely diffused, the thermal stability of the probe is improved, and the influence of temperature drift on detection signals is reduced; meanwhile, the volume of the probe is reduced, and the spatial resolution of the probe is improved. (b) Under different application scenes, the decoupling of different degrees of electromagnetic coupling effect between adjacent detection coils can be realized by moving the metal sliding sheets on the auxiliary coils without redesigning and manufacturing the probes.
Drawings
FIG. 1 is a general block diagram of an array probe of the present invention;
FIG. 2 is a block diagram of a sub-probe of the present invention;
fig. 3 is a sub-probe coil current loading embodiment of the present invention.
Detailed Description
An overall structure diagram of the array probe designed by the invention is shown in figure 1. The probe consists of a plurality of independent sub-probes (10) spaced apart from each other by a distance, each sub-probe having the same structure: the detection coil (1) is externally provided with a first auxiliary coil (2) and a second auxiliary coil (3), which are coaxial with the detection coil (1) and are respectively positioned at the upper end and the lower end of the detection coil (1). The detection coil (1) is a hollow cylindrical coil, the first auxiliary coil (2) and the second auxiliary coil (3) are solenoid coils, and the windings of the detection coil (1), the first auxiliary coil (2) and the second auxiliary coil (3) are separated. The first auxiliary coil (2) is in contact with and conducted with the first metal sliding sheet (4), and the second auxiliary coil (3) is in contact with and conducted with the second metal sliding sheet (5). Two terminals of the detection coil (1) are connected with a loading circuit (6), and the first auxiliary coil (2) and the second auxiliary coil (3) are respectively connected with a first auxiliary loading circuit (7) and a loading circuit (8). The currents output by the loading circuit (6), the first auxiliary loading circuit (7) and the second auxiliary loading circuit (8) have the same frequency. The first metal sliding sheet (4) and the second metal sliding sheet (5) are arranged on the guide rail (9), and the length and the number of turns of the first auxiliary loading circuit (7) and the second auxiliary loading circuit (8) which are respectively connected with the first auxiliary coil (2) and the second auxiliary coil (3) can be respectively changed by moving the first metal sliding sheet (4) and the second metal sliding sheet (5) on the guide rail (9). When the loading circuit (6) is switched on, the detection coil (1) generates an excitation magnetic field which, on the one hand, induces eddy currents in the component to be detected for detection and, on the other hand, the radial component of which also influences the detection coil adjacent thereto, producing an electromagnetic coupling effect. When the first auxiliary loading circuit (7) and the second auxiliary loading circuit (8) are connected, the magnetic fields generated by the first auxiliary coil (2) and the second auxiliary coil (3) are opposite to the exciting magnetic field generated by the detection coil (1), and the magnetic fields are rapidly attenuated in the axial direction. The magnetic field can largely counteract the radial component of the exciting magnetic field generated by the detection coil (1), and has little influence on the axial magnetic field of the eddy current excited in the detected member, thereby weakening the electromagnetic coupling between the adjacent detection coils and not influencing the detection capability of the probe.
Fig. 2 shows a sub-probe structure of an array eddy current probe implemented by the method of the present invention. The sub-probe (10) comprises a detection coil (1), a first auxiliary coil (2), a second auxiliary coil (3), a metal sliding sheet (4), a metal sliding sheet (5), a guide rail (9), a detection coil framework (11), an auxiliary coil framework (12), a shell (13), an elastic gasket (14), a support plate (15), an aviation socket (16) and a 4-core cable (17). The detection coil (1) is wound on the detection coil framework (11), and the first auxiliary coil (2) and the second auxiliary coil (3) are wound on the auxiliary coil framework (12). The guide rail (9) is arranged on the shell (13) and is marked with scales. The first metal sliding sheet (4) and the second metal sliding sheet (5) are arranged on the guide rail (9), and the contacts of the first metal sliding sheet and the second metal sliding sheet are respectively communicated with the first auxiliary coil (2) and the second auxiliary coil (3). Two terminals of the detection coil (1) are connected with the 1 st core and the 2 nd core of the 4-core cable (17) through aviation sockets (16); the upper terminal of the first auxiliary coil (2) is connected with the 3 rd core of the 4-core cable (17); the lower terminal of the second auxiliary coil (3) is connected to the 4 th core of the 4-core cable (17). The 1 st and the 2 nd core of the 4-core cable (17) are connected into the loading circuit (6), the first metal sliding sheet (4) and the 3 rd core of the 4-core cable (17) are connected into the loading circuit (7), and the second metal sliding sheet (5) and the 4 th core of the 4-core cable (17) are connected into the loading circuit (8). The first metal sliding sheet (4) and the metal sliding sheet (5) are moved according to scales on the guide rail (9), and the lengths of the second auxiliary coil (3) and the second auxiliary coil (3) which are respectively connected into the first auxiliary loading circuit (7) and the second auxiliary loading circuit (8) can be controlled. The sub-probes (10) are mounted in suspension on a support plate (15) of the array probe by means of elastic washers (14) and aviation sockets (16).
The arrangement of the auxiliary coils is not limited to the above-described arrangement of a set of coils, including but not limited to a single coil, a symmetrical arrangement of a plurality of sets of coils, and the like, as long as the radial component of the excitation magnetic field generated by the detection coil can be canceled.
Fig. 3 shows a sub-probe coil current loading embodiment of the present invention. If the rotation directions of the three coils of the detection coil (1), the first auxiliary coil (2) and the second auxiliary coil (3) are the same, the same-phase current is loaded in the first auxiliary coil (2) and the second auxiliary coil (3), and the current opposite to the first two currents is loaded in the detection coil (1); if the rotation directions of the first auxiliary coil (2) and the second auxiliary coil (3) are the same and opposite to the rotation direction of the detection coil (1), the three coils are loaded with currents with the same phase; if the rotation directions of the detection coil (1) and the first auxiliary coil (2) are the same and opposite to the rotation direction of the second auxiliary coil (3), the detection coil (1) and the second auxiliary coil (3) load the same-phase current, and the first auxiliary coil (2) loads the current opposite to the first auxiliary coil and the second auxiliary coil; if the rotation directions of the detection coil (1) and the second auxiliary coil (3) are the same and opposite to the rotation direction of the first auxiliary coil (2), the detection coil (1) and the first auxiliary coil (2) load the same-phase current, and the second auxiliary coil (3) loads the opposite-phase current.
Claims (5)
1. An array eddy current probe for actively relieving electromagnetic coupling between adjacent coils is characterized in that: a first auxiliary coil (2) and a second auxiliary coil (3) are arranged on the periphery of each detection coil (1) of the array probe, and the external magnetic field of an excitation magnetic field generated by the detection coils (1) is weakened by adjusting the length and the number of turns of the first auxiliary coil (2) and the second auxiliary coil (3), so that the mutual interference of magnetic fields generated by adjacent detection coils of the array probe is reduced;
if the rotation directions of the three coils of the detection coil (1), the first auxiliary coil (2) and the second auxiliary coil (3) are the same, the same-phase current is loaded in the first auxiliary coil (2) and the second auxiliary coil (3), and the current opposite to the first two currents is loaded in the detection coil (1); if the rotation directions of the first auxiliary coil (2) and the second auxiliary coil (3) are the same and opposite to the rotation direction of the detection coil (1), the three coils are loaded with currents with the same phase; if the rotation directions of the detection coil (1) and the first auxiliary coil (2) are the same and opposite to the rotation direction of the second auxiliary coil (3), the detection coil (1) and the second auxiliary coil (3) load the same-phase current, and the first auxiliary coil (2) loads the current opposite to the first auxiliary coil and the second auxiliary coil; if the rotation directions of the detection coil (1) and the second auxiliary coil (3) are the same and opposite to the rotation direction of the first auxiliary coil (2), the detection coil (1) and the first auxiliary coil (2) load the same-phase current, and the second auxiliary coil (3) loads the opposite-phase current.
2. An array eddy current probe for actively decoupling electromagnetic coupling between adjacent coils as recited in claim 1, wherein: the detection coil (1) is a hollow cylindrical coil; the first auxiliary coil (2) and the second auxiliary coil (3) are solenoid coils which are coaxial with the detection coil (1) and are respectively positioned at the upper end and the lower end of the detection coil (1).
3. An array eddy current probe for actively decoupling electromagnetic coupling between adjacent coils as recited in claim 1, wherein: the windings of the detection coil (1), the first auxiliary coil (2) and the second auxiliary coil (3) are separated.
4. An array eddy current probe for actively decoupling electromagnetic coupling between adjacent coils as recited in claim 1, wherein: the two terminals of the detection coil (1) are connected with the loading circuit (6), the first auxiliary coil (2) is in contact with and is conducted with the first metal sliding sheet (4), the second auxiliary coil (3) is in contact with and is conducted with the second metal sliding sheet (5), the first auxiliary coil (2) and the second auxiliary coil (3) are respectively connected with the first auxiliary loading circuit (7) and the second auxiliary loading circuit (8), and currents output by the loading circuit (6), the first auxiliary loading circuit (7) and the second auxiliary loading circuit (8) have the same frequency.
5. An array eddy current probe for actively decoupling electromagnetic coupling between adjacent coils as recited in claim 4, wherein: the first metal sliding sheet (4) and the second metal sliding sheet (5) are arranged on the guide rail (9), and the length and the number of turns of the first auxiliary loading circuit (7) and the second auxiliary loading circuit (8) which are respectively connected with the first auxiliary coil (2) and the second auxiliary coil (3) can be respectively changed by moving the first metal sliding sheet (4) and the second metal sliding sheet (5) on the guide rail (9).
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| CN202010679303.6A CN111812193B (en) | 2020-07-15 | 2020-07-15 | Array eddy current probe for actively relieving electromagnetic coupling between adjacent coils |
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| CN202010679303.6A CN111812193B (en) | 2020-07-15 | 2020-07-15 | Array eddy current probe for actively relieving electromagnetic coupling between adjacent coils |
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| CN112711876B (en) * | 2020-12-17 | 2022-09-13 | 中国人民解放军国防科技大学 | Dipole uniform magnetic field coil design method capable of reducing magnetic shielding coupling effect |
| CN113311065B (en) * | 2021-05-25 | 2024-01-23 | 北京航空航天大学 | Coil probe heat dissipation method for pulsed eddy current detection |
| CN113777155B (en) * | 2021-09-09 | 2024-05-03 | 国家石油天然气管网集团有限公司华南分公司 | Vortex probe based on Halbach array coil |
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| SU441512A1 (en) * | 1970-09-17 | 1974-08-30 | Предприятие П/Я Р-6575 | Contactless electrodynamic sensor |
| JPH0673293B2 (en) * | 1983-10-25 | 1994-09-14 | 日本電子株式会社 | Disturbance magnetic field canceling device |
| JPH0741468U (en) * | 1993-12-27 | 1995-07-21 | 株式会社ユニシアジェックス | Rotation sensor |
| US6307370B1 (en) * | 1999-07-02 | 2001-10-23 | Bruker Ag | Active shielded superconducting assembly with improved compensation of magentic field disturbances |
| WO2015118508A1 (en) * | 2014-02-07 | 2015-08-13 | Instituto De Engenharia De Sistemas E Computadores - Investigação E Desenvolvimento | Eddy current probe with differential magnetic field sensors |
| CN106710855B (en) * | 2017-02-09 | 2024-06-04 | 东莞市华盾电子科技有限公司 | Coil structure of passing detector and passing detector |
| US10324141B2 (en) * | 2017-05-26 | 2019-06-18 | Allegro Microsystems, Llc | Packages for coil actuated position sensors |
| CN109884371B (en) * | 2019-03-04 | 2020-02-14 | 华中科技大学 | Anti-skin-effect large-current measuring device |
| CN109920633A (en) * | 2019-03-21 | 2019-06-21 | 惠州市纬特科技有限公司 | Reduce the transformer of electromagnetic interference |
| CN110496768B (en) * | 2019-09-03 | 2020-12-22 | 厦门大学 | Double-coil electromagnetic ultrasonic transducer capable of eliminating electromagnetic interference |
| CN110817789B (en) * | 2019-11-13 | 2023-07-25 | 青岛歌尔智能传感器有限公司 | Combined sensor and manufacturing method thereof |
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Effective date of registration: 20240617 Address after: 430074 Jindihua Mansion, No. 12 Yujiahu Road, Wuhan Donghu New Technology Development Zone, Wuhan City, Hubei Province Patentee after: WUHAN HUAYUYIMU TESTING EQUIPMENT CO.,LTD. Country or region after: China Address before: 411105 College of mechanical engineering, Xiangtan University, yanggutang street, Yuhu District, Xiangtan City, Hunan Province Patentee before: XIANGTAN University Country or region before: China |