CN1022647C - Efficient probe for non-destructive detection of far-field eddy - Google Patents
Efficient probe for non-destructive detection of far-field eddy Download PDFInfo
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- CN1022647C CN1022647C CN 90105697 CN90105697A CN1022647C CN 1022647 C CN1022647 C CN 1022647C CN 90105697 CN90105697 CN 90105697 CN 90105697 A CN90105697 A CN 90105697A CN 1022647 C CN1022647 C CN 1022647C
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Abstract
The present invention relates to an efficient and practical probe for non-destructive detection of far-field eddies. On the basis of the existing probe composed of an excitation coil and a detection coil, the present invention uses three measures: a magnetic loop is arranged on the excitation coil, or a magnetic loop is arranged on the detection coil, or a compensating coil is additionally arranged between the excitation coil and the detection coil; the present invention can use the method of the combination of two or three measures; thus, the present invention overcomes fatal disadvantages that the weak output signals of the existing probe, large excitation power and over-long probe; the present invention can be used for detecting the thickness of various ferromagnetic and non-ferromagnetic electric conduction tubes, tubular components and pipelines, the performance of electric conduction and magnetic conduction, destruction and abnormality.
Description
Efficient probe for non-destructive detection of far-field eddy belongs to the eddy detection technology of electromagnetic detection class in the Dynamic Non-Destruction Measurement.
Remote field eddy current technology was invented April nineteen forty-six, and run after fame; obtain United States Patent (USP) in November 6 nineteen fifty-one, the patent No. is 2573799 with " measuring the device of iron pipe thickness with magnetic methods " (original text is: Apparatus for magnetically measuring thickness of ferrous pipe ").This technology begins to be used to detect the damage of oil well pipe box latter stage from the fifties after some improvement.But until today, it is very limited in other Application for Field, and its main cause is, the problem that existing Remote Field Eddy Current Probe up to now also exists some to solve, comprising:
(1) probe used low excitation frequency, had seriously limited detection speed;
(2) probe output is very faint, and generally about the microvolt level, signal to noise ratio (S/N ratio) is very little, brings difficulty for signal testing and processing;
(3) probe length can not be accomplished doubly to manage below the interior diameter less than 2-3, and the axial length of probe is long, makes it in pipeline inconvenience in service, even may not;
(4) need bigger exciting power.
More than all connect each other between 4, for example,, then mean equally under same output signal if can under same frequency, improve output signal level, improve excitation frequency and improve detection speed.And for example,, equally also mean under same exciting power, can improve output signal level, also have, shorten the probe axial length, output signal level is suitably improved if can reduce exciting power.
The basic structure of existing Remote Field Eddy Current Probe " U. S. application number on May 11st, 262155,81 be EP65325 " as shown in Figure 1." utilizing the damaged of objects such as far-field eddy device pipelines ".It is one and the coaxial mounted device of detected metal tube (5), and the one end is wound with a coaxial drive coil (1) (being called source coil in the document).Apart from about two, the three times of detected pipe interior diameter places of drive coil (1), settle one or one group of magnetic test coil (2) (claiming detector in the document).Its ultimate principle is, the drive coil (1) that passes to low frequency ac is set up a low frequency alternating magnetic field around it, the part of its energy is propagated along inner axial tube, arrive magnetic test coil, this coupling is referred to as direct coupling, its travel path is shown in (3) in the accompanying drawing 1, another part energy is located directly to pass tube wall (5) at drive coil (1) and is axially propagated outside pipe, because the outer energy of propagating of pipe no longer is subjected to the obstruction of eddy current in the wall, and between the magnetic test coil (4), if the distance of establishing between drive coil (1) and the magnetic test coil (4) is S, tested metal tube internal diameter is Di, then S=(0.5-1.0) Di.Between compensating coil (3) and the drive coil (1) is (0.5-0.6) S apart from Sc.Work as S=1.0Di, during Sc=0.5S, the number of turn Wc of compensating coil (3) is about 1/10 We * (the drive coil number of turn), and when Sc reduces, then Wc increases, and Sc is tending towards at 0 o'clock, and Wc approaches Wex.Compensating coil (3) also can a circuit in parallel or network, so that in limited range, adjust the resistance value that the compensating coil electric current is promptly adjusted parallel circuit or network, to adjust the phase place and the amplitude of compensating coil electric current in certain limit, make to be placed on the magnetic test coil induced potential amplitude minimum that requires to occur far field phenomenon location in the design, and phase curve is smooth.
The magnetic loop (5) that is arranged on magnetic test coil (4) also is to be made by high magnetic conduction, the difficult magnetic material that produces eddy current.Because of the magnetic flux density Bp in this magnetic loop is very little, so the physical dimension of this magnetic loop under the prerequisite that guarantees physical strength, can be done very thinly.Magnetic test coil (4) number of turn Wp determines, satisfy the test request of output signal.
Claims (7)
1, a kind of efficient probe for non-destructive detection of far-field eddy comprises drive coil, magnetic test coil and axle, it is characterized in that magnetic test coil is that 0.5 to 1 times of tested metal tube internal diameter is located in the distance drive coil, place the energy of electromagnetic field that drive coil can be sent to concentrate drive coil, the enhancing signal amplitude reduces in the magnetic loop of direct coupling energy.
2, a kind of efficient probe for non-destructive detection of far-field eddy comprises drive coil, magnetic test coil and axle, it is characterized in that it is that 0.5 to 1 times of tested metal tube internal diameter is located that magnetic test coil places apart from drive coil, and magnetic test coil placed can drain a small amount of magnetic flux from the tube wall in far-field region, increase in the magnetic loop of amplitude output signal.
3, a kind of efficient probe for non-destructive detection of far-field eddy comprises drive coil, magnetic test coil and axle, it is characterized in that it is that 0.5 to 1 times of tested metal tube internal diameter is located that magnetic test coil places apart from drive coil, between drive coil and magnetic test coil, with the distance of drive coil be 0.6 times of two coil distances with interior, setting and drive coil differential concatenation to curb its number of turn that the energy in the direct coupling channel flows within the specific limits be the compensating coil of 1/10 to 1 times of drive coil number of turn.
4, a kind of efficient probe for non-destructive detection of far-field eddy as claimed in claim 1, it is characterized in that between drive coil and the magnetic test coil, from the distance of drive coil be two coil-spans from 0.6 times of its number of turn that curbs the energy stream in the direct coupling channel within the specific limits with interior, setting and drive coil differential concatenation be the compensating coil of 1/10 to 1 times of drive coil number of turn.
5, a kind of efficient probe for non-destructive detection of far-field eddy as claimed in claim 1 is characterized in that magnetic test coil places the magnetic loop that can drain a small amount of magnetic flux increase amplitude output signal from the tube wall in far-field region.
6, a kind of efficient probe for non-destructive detection of far-field eddy as claimed in claim 2, it is characterized in that between drive coil and the magnetic test coil, from the distance of drive coil be two coil-spans from 0.6 its number of turn that curbs energy stream in the direct coupling channel within the specific limits with interior, setting and drive coil differential concatenation be the compensating coil of 1/10 to 1 times of drive coil number of turn.
7, a kind of efficient probe for non-destructive detection of far-field eddy as claimed in claim 5, it is characterized in that between drive coil and the magnetic test coil, from the distance of drive coil be two coil-spans from 0.6 times of its number of turn that curbs the energy stream in the direct coupling channel within the specific limits with interior, setting and drive coil differential concatenation be the compensating coil of 1/10 to 1 times of drive coil number of turn.Thereby propagate into apart from drive coil than after the distant place, the pipe outfield powerful in pipe field intensity, enter in the pipe arrival magnetic test coil (2) so will pass tube wall (5) again at the outer axially energy of propagation of pipe, this coupling is called indirect coupling, and its path is shown in (4) of accompanying drawing 1.When magnetic test coil is nearer apart from drive coil, directly coupled signal is preponderated, and direct coupled zone or near field region are in this zone, when magnetic test coil apart from drive coil far when (about 2-3 doubly manages outside the interior diameter), the indirect coupling signal is preponderated, and the far-field region is named in this zone.
Only magnetic test coil is being placed under the condition in far-field region, the detected signal phase of magnetic test coil lags behind with respect to the drive coil current phase, just proportional substantially with the pipe wall thickness, and the damage on conduction, magnetic conduction character and the pipe thickness of reflection pipe or unusual.
Though existing at present people proposed some solutions in succession to the problem that existing probe exists, as between near field region and magnetic test coil, powering up (or magnetic) shielding, or in the magnetic test coil circuit, introduce the signal etc. of reflection drive coil level and phase place, but they or actual effect are not obvious, perhaps have some difficulties on technology realizes.
The objective of the invention is to design and manufacture a kind of output signal amplitude height that has, exciting power is little, and the probe axial length is short, is cost with suitable sacrifice amplitude output signal perhaps, use higher excitation frequency of operation, improve the novel Remote Field Eddy Current Probe that engineering is used of being convenient to of test speed.
Realization the present invention seeks on the basis of existing Remote Field Eddy Current Probe, takes three measures to constitute three technical solutions independent of each other respectively, and the two or three's combined method in three measures reconstruct four technical solutions respectively.
Three concrete measures (constituting three concrete technical schemes) are:
(1) drive coil is provided with magnetic loop, promptly whole drive coil places magnetic loop.Its function is that the energy of electromagnetic field that drive coil is sent is concentrated.Make that like this being diffused into electromagnetic field all around from coil weakens greatly, to reduce direct coupling energy.Thereby reach the purpose of compression near field region,, strengthen the electromagnetic intensity in far-field region, improve the output signal amplitude to shorten probe length.And in the tube wall under the technical requirement of high magnetic field intensity, reduce exciting power greatly given;
(2) compensating coil of setting and drive coil differential concatenation between drive coil and magnetic test coil.Its function is the energy stream that curbs more up hill and dale within the specific limits in the direct coupling channel, makes far field phenomenon and far-field region appear at the zone of designing requirement, reaches the shortening probe length, improves the output signal amplitude, reduces the purpose of exciting power;
(3) magnetic test coil is provided with magnetic loop.Its effect is that " drainage " goes out a small amount of magnetic track from the inner tubal wall in far-field region, thereby has increased amplitude output signal extremely effectively.
In above-mentioned three measures the two or three's the technical scheme that combination constituted are:
(1) with two combinations of one of above-mentioned measure with measure.Promptly both drive coil was placed magnetic loop, the compensating coil with the drive coil differential concatenation was set between drive coil and magnetic test coil again;
(2) with three combinations of one of above-mentioned measure with measure.Promptly respectively drive coil and magnetic test coil are placed magnetic loop;
(3) with above-mentioned measure two with measure three the combination.Compensating coil with the drive coil differential concatenation promptly both had been set between drive coil and magnetic test coil, again magnetic test coil had been provided with magnetic loop;
(4) above-mentioned three measures are combined into best technical solution, promptly both drive coil and magnetic test coil were placed magnetic loop respectively, the compensating coil with the drive coil differential concatenation is set between drive coil and magnetic test coil again simultaneously.
Above-mentioned seven technical solutions, belong to a total design, finish same purpose, promptly can both solve purpose of the present invention, but the emphasis and the degree of dealing with problems are different, so all technical schemes of the present invention, in engineering is used, applicability is stronger, can be used to detect wall thickness, conduction and magnetic property and the damage wherein and unusual of various ferromagnetic and non-ferromagnetic conductive tube, tubular member and pipelines.
Accompanying drawing 1 is existing Remote Field Eddy Current Probe structural representation.Its basic structure is made of drive coil (1) and magnetic test coil (2).The path that energy of electromagnetic field is propagated is represented with (4) in (3) among the figure.(5) among the figure are tested metal tubes.
Accompanying drawing 2 is the example structure synoptic diagram of best-of-breed technology scheme of the present invention.
By this best-of-breed technology scheme implementation example structural representation, i.e. the basic structure of all technical schemes of the present invention and implementation method thereof as can be known.Now 2 be described below in conjunction with the accompanying drawings:
(7) among the figure are tested metal tube.Its far-field eddy detection probe (8) is by drive coil (1), drive coil magnetic loop (2), and compensating coil (3), magnetic test coil (4) and magnetic test coil magnetic loop (5) and axle (6) constitute.As seen from the figure, it is that whole drive coil (1) is placed magnetic loop (2), and magnetic loop (2) is made by high magnetic conduction, the difficult magnetic material that produces eddy current.Because of the general Bex of magnetic flux density≤0.01 tesla in the excitation magnetic loop, so the physical dimension of magnetic loop considers from physical strength and production technology that mainly the number of turn Wex of magnetizing coil determines and will mate with the impedance phase of power supply; Place drive coil (1) with the compensating coil (3) of drive coil (1) differential concatenation
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 90105697 CN1022647C (en) | 1990-07-07 | 1990-07-07 | Efficient probe for non-destructive detection of far-field eddy |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 90105697 CN1022647C (en) | 1990-07-07 | 1990-07-07 | Efficient probe for non-destructive detection of far-field eddy |
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| Publication Number | Publication Date |
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| CN1058097A CN1058097A (en) | 1992-01-22 |
| CN1022647C true CN1022647C (en) | 1993-11-03 |
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| CN 90105697 Expired - Fee Related CN1022647C (en) | 1990-07-07 | 1990-07-07 | Efficient probe for non-destructive detection of far-field eddy |
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Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN100392391C (en) * | 2005-01-17 | 2008-06-04 | 林俊明 | Inside-through type low frequency electromagnetic detection sensor |
| CN102183579B (en) * | 2011-02-21 | 2012-11-14 | 南京农业大学 | Eddy current testing probe |
| CN102411028A (en) * | 2011-08-24 | 2012-04-11 | 中国科学院等离子体物理研究所 | Eddy-current nondestructive detection method of high-heat load component connection quality for nuclear fusion device block pipe structure |
| CN102645157B (en) * | 2012-05-03 | 2014-07-09 | 常州机电职业技术学院 | Eddy current detection probe |
| CN102879462B (en) * | 2012-10-27 | 2015-04-15 | 浙江大学 | Metal defect eddy current detection device and probe thereof |
| CN103868986B (en) * | 2012-12-13 | 2017-06-16 | 上海海事大学 | The eddy current probe and its detection method of a kind of metallic conduit defect in inner surface |
| CN103969340B (en) * | 2014-04-21 | 2016-07-06 | 西安交通大学 | A kind of all-round radial battery electromagnet ultrasonic changer |
| CN105241952B (en) * | 2015-10-30 | 2018-03-23 | 湘潭大学 | A kind of channel bend defect inspection method and detection means based on far-field eddy |
| CN106501355A (en) * | 2016-12-14 | 2017-03-15 | 中国计量大学 | A kind of metallic conduit defect detecting device based on far-field eddy |
| CN107478715B (en) * | 2017-07-03 | 2020-12-25 | 岭东核电有限公司 | Nondestructive testing analysis method, device and system for heat transfer pipe of heat exchanger of nuclear power station |
| CN111505121A (en) * | 2020-05-22 | 2020-08-07 | 西安交通大学 | Interpolation type full-coil structure electromagnetic ultrasonic longitudinal guided wave probe and nondestructive testing method |
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