CN209264631U - A kind of dual frequency array eddy current probe - Google Patents
A kind of dual frequency array eddy current probe Download PDFInfo
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- CN209264631U CN209264631U CN201822258207.5U CN201822258207U CN209264631U CN 209264631 U CN209264631 U CN 209264631U CN 201822258207 U CN201822258207 U CN 201822258207U CN 209264631 U CN209264631 U CN 209264631U
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Abstract
The utility model belongs to electromagnetic nondestructive testing field, is related to a kind of dual frequency array eddy current probe.The utility model probe includes exciting element, detecting element and rectangle mounting groove (8);Mounting groove top cover (9) are provided on the rectangle mounting groove (8);The exciting element includes big excitation coil (1), small excitation coil (2) and interior fixed skeleton (3);Around fixing on skeleton (3) inside, big excitation coil (1) is wound on small excitation coil (2) the small excitation coil (2);The detecting element includes detection coil (4), shielding case outer cylinder (5), shielding case top cover (6) and wrapping post (7);The wrapping post (7) is mounted on rectangle mounting groove (8) slot bottom, the detection coil (4) covers on wrapping post (7), and is located in the shielding shell of magnetic field shielding case outer cylinder (5) and shielding case top cover (6) composition.The utility model probe detection depth is big, and detection efficiency is high.
Description
Technical field
The utility model belongs to electromagnetic nondestructive testing field, be related to be suitable for petrochemical industry, space flight and aviation and other
The eddy current sensor of essential industry field defects detection more particularly to a kind of dual frequency array eddy current probe.
Background technique
EDDY CURRENT is one of conventional non-destructive testing technology, is widely used in for industries such as petrochemical industry, electric power metallurgy,
And the key areas such as aerospace, nuclear power generating equipment, for ensureing equipment operational safety, evaluation equipment life, reducing equipment dimension
Shield cost etc. is of great significance.Eddy current detection method is based on electromagnetic induction principle, using excitation coil in test specimen
Gyrate induction alternating current is generated, position and the size of defect are judged by the voltage signal variation of coil, is a kind of
The effective ways of quantitative Nondestructive Evaluation are carried out to material surface and near surface flaw.When the vortex density in material reaches material table
Face vortex density 37% when depth of material be vortex standard osmotic depth.Eddy current signal in this depth can detecte
It arrives, the eddy current signal greater than this depth just can't detect.Restrict vortex penetration depth because being known as driving frequency, exciting current
Size and the electromagnetic property of material etc..Relative to other lossless detection methods, eddy current detection method has non-contact, detection speed
The advantage of the quantitative aspect of fast feature and checking is spent, test specimen can be carried out quick in the case where probe does not contact test specimen
Detection.But conventional vortex detection method carries out scanning using single coil, and detection accuracy and validity are difficult to ensure, detects speed
Slowly, there is very big deficiency in the scanning of large area plate and deep zone defect context of detection.
Conventional array eddy detection technology uses the coil of multiple autonomous workings, arranges, overcomes according to particular form
Conventional vortex sensor detects slow-footed disadvantage, detection sensitivity with higher and detection speed.In recent years, both at home and abroad specially
Family scholar develops a variety of advanced Array eddy-current probes, has been successfully applied to many industrial nondestructive testing fields.But array whirlpool
The coil unit of flow sensor is numerous, while improving detection efficiency, precision, there is also between coil unit mutual inductance interference and
The problems such as signal excitation, Acquisition Circuit design cumbersome conflict.Detection sensitivity is caused to reduce the mutual inductance interference between coil
The problem of, common multiplex electronics technology increases hub of a spool and is improved away from the methods of, data difference processing, but not
It can fundamentally solve.
The country has scholar using driving source of the square coil as Array eddy-current probe, by making excitation coil and detection line
Coil axis is vertical, to reduce interference of the excitation coil to detection coil.When coil of rectangular carrying current motivates, there is no existing from offsetting
As the penetration depth of obtained vortex is deeper, stronger to the detectability of deep zone defect.But vortex caused by it there are still
Kelvin effect problem, the size for being vortexed penetration depth are still limited by the height of driving frequency, still can not obtain to compared with deep torn grain
Obtain ideal testing result.It is seeped although Array eddy-current probe can increase vortex within the scope of certain frequency by using low-frequency excitation
Saturating depth, improves the ability of probe detection deep zone defect, but low frequency will lead to probe simultaneously resolution ratio is low, signal-to-noise ratio is low, and draw
The problems such as sending out the speed effect and difficult detection signal resolution of probe.
Chinese patent CN208076453U discloses a kind of double frequency excitation circular vortex spy for detecting heavy wall deep torn grain defect
Head, using round excitation coil, though it is non-directional, have an impact to the magnetic field of circle detection coil, detects in signal noise slightly
Greatly, and coil dimension is big, and detection depth is not so good as the depth using square coil excitation coil.
To sum up, main problem of the existing technology has: (1) being vortexed penetration depth caused by existing conventional vortex probe
It is too small, it is limited to the detectability of deep torn grain;(2) detection signal is influenced vulnerable to excitation field, and detection resolution is caused to reduce;
(3) there are problems that missing inspection to defect and crackle;(4) problem of signal resolution difficulty is detected;(5) detection speed is slow.
Therefore, research is suitable for the currents sensing of petrochemical industry, space flight and aviation and other essential industry field defects detections
Device, effectively to identify large area heavy wall plate, metal welding seam, deep torn grain and deep zone defect present in aircraft overall structure,
It is of great significance in terms of maintenance of equipment, industrial products real-time detection and structural strength and prospect.
Utility model content
For overcome the deficiencies in the prior art, above-mentioned problems of the prior art, the purpose of this utility model are solved
It is to provide a kind of dual frequency array eddy current probe, using the form excitation coil of two double-frequency synchronous reverse energizations as excitation
Source, to provide the uniform turbulence distribution with larger penetration depth.It is compared with existing eddy current array probe technology, the utility model
The detection depth of crackle can be improved, while there is high-resolution and higher detection speed, it can be to present in detection material
Deep torn grain and deep zone defect realize large area high speed on-line checking, provide accurately and reliably for the qualitative assessment of industrial equipment and product
Foundation.
The technical solution adopted in the utility model is: a kind of dual frequency array eddy current probe, including exciting element, detecting element
With the rectangle mounting groove of both ends open, the exciting element and detecting element are mounted in rectangle mounting groove, and detecting element is located at
Below exciting element, the two axis is vertical;The mounting groove top cover detachably installed is additionally provided on the rectangle mounting groove;It is special
Sign is: the exciting element includes big excitation coil, small excitation coil and interior fixed skeleton;The small excitation coil is wound on
On interior fixed skeleton, the big excitation coil is wound on small excitation coil, by big excitation coil, small excitation coil and interior fixation
The exciting element entirety nesting that skeleton is constituted is mounted in the rectangle mounting groove, axial and rectangle mounting groove opening direction one
It causes;
The detecting element has n2A, wherein n any one integer between 2-6, each detecting element include 1 detection
Coil, 1 shielding case outer cylinder, 1 shielding case top cover, 1 wrapping post;The wrapping post is arranged in array, vertical to be fixedly mounted
On the rectangle mounting groove slot bottom;The shielding case outer cylinder is in hollow tube-shape and both ends open;The shielding case top cover is in piece
Shape;The detection coil, shielding case outer cylinder are sequentially sleeved on wrapping post, and the shielding case top cover is removably mounted at outside shielding case
Cylinder top;The shielding case outer cylinder and shielding case top cover collectively form the shielding shell of detection coil;On all shielding case top covers
Surface flushes.
The big excitation coil and small excitation coil are rectangular vortex coil.
Further, the wrapping post can arrange in matrix, any one shape in such as 2 × 2,3 × 3,4 × 4,5 × 5,6 × 6
Formula arrangement.
Further, the big excitation coil and small excitation coil are rectangular vortex coil.
Further, the detection coil is circular vortex coil, and diameter is less than the width of small excitation coil, for acquiring material
Signal of Cracks in material.
Further, n=4.
Further, the sinusoidal alternating current that frequency is different, size of current is different, phase is different is respectively adopted to swash greatly to described
It encourages coil and small excitation coil is motivated, to generate the vortex with larger penetration capacity in the material.
Further, the big excitation coil, small excitation coil and interior fixed skeleton axis are overlapped, both ends end face respectively with
Two ports of rectangle mounting groove flush, and relative position is kept to immobilize.
Further, the detection coil is arranged in array, positioned at the underface of big excitation coil.
Further, the big excitation coil lower surface is contacted with shielding case top cover upper surface.
Further, the shielding case outer cylinder, detection coil and shielding case top cover axis are overlapped.
Further, the detection coil lead outlet being pierced by for detection coil lead is provided on the shielding case outer cylinder cylinder
Hole.
Further, for the setting of rectangle mounting groove two sidewalls upper end there are two symmetrical conduit, the mounting groove top cover is logical
The symmetrical conduit is crossed detachably to install with rectangle mounting groove.
Further, the rectangle mounting groove, mounting groove top cover, wrapping post and interior fixed skeleton are made of PVC material.
Further, the big excitation coil, small excitation coil and detection coil are formed by enameled wire coiling.
Further, the long L in section of the big excitation coilx1=50mm, axial long Ly1=50mm, the high L in sectionz1=9mm, thick Δ
t1=1mm, the long L in section of the small excitation coilx2=48mm, axial long Ly2=50mm, the high L in sectionz2=7mm, thick Δ t2=1mm, institute
State the outer radius r of detection coilo3=1.6mm, inside radius ri3=0.6mm, high hc3=0.8mm。
Further, multiple scanning frame mounting holes are provided on the rectangle mounting groove, be used for described in the utility model one
Kind dual frequency array eddy current probe integral installation is on scanning frame.
It is further preferred that being symmetrically distributed on mounting groove top cover there are two the scanning frame mounting holes.
Further, the lead being additionally provided on the rectangle mounting groove for big excitation coil, small excitation coil is pierced by rectangle
The first outlet hole of mounting groove and the second outlet hole that rectangle mounting groove is pierced by for the lead of detection coil.
It is further preferred that the first outlet hole is located on mounting groove top cover, the second outlet hole is located at rectangle mounting groove
Side wall on.
A kind of assembly method of dual frequency array eddy current probe described in the utility model are as follows:
Firstly, wrapping post is vertically fixedly mounted on rectangle mounting groove slot bottom, it will test coil and cover on wrapping post, then
By shielding case outer sleeve outside detection coil, the lead that will test coil is pierced by shielding case outer cylinder, finally in shielding case outer cylinder
Shielding case top cover is installed on top, and the assembling of all detecting elements is completed with method.Each detection coil and its corresponding shielding case outer cylinder,
Shielding case top cap central should be kept coaxially, and all shielding case top covers upper surface flushes.
Secondly, small excitation coil is wound on interior fixed skeleton, then big excitation coil is wound on small excitation coil,
Then by the exciting element entirety being made of interior fixed skeleton, small excitation coil with big excitation coil it is nested be installed on rectangle installation
In slot, it is located at the surface of detecting element, and the big lower surface of excitation coil and the upper surface of shielding case top cover are in contact.
Big excitation coil, small excitation coil and interior fixed skeleton axis are overlapped, both ends end face respectively with two ports of rectangle mounting groove
It flushes, center line keeps coaxial, and relative position is kept to fix.
Then, mounting groove top cover is installed on rectangle mounting groove, the lead of all coils is pierced by rectangle mounting groove.
Finally, entire probe is mounted on scanning frame.
Based on above scheme, another technical solution that the utility model uses is: a kind of to utilize a kind of above-mentioned double frequency battle array
The method that column eddy current probe detects deep torn grain, it is characterised in that: the following steps are included:
S1. it probe assembly: is assembled according to the above method;
S2. the lead of big excitation coil and small excitation coil is connected to two AC power sources, will test the coil of coil
Lead is connected to oscillograph, to apply pumping signal, to receive testing result;
S3. it is different that different frequency, size of current difference, phase are continually fed into big excitation coil and small excitation coil
Steady-state sine alternating current motivated;
S4. so that probe is carried out scanning on material for test surface, use when scanning and probe scanning path orthogonal two
Secondary scanning mode detects surface of test piece, can be detected with guaranteeing transversal crack and longitudinal crack;The whirlpool of fault location
Disturbance of the flow field by defect is fed back defect information into detection coil by disturbed magnetic field;
S5. the detection signal that will test in coil is input in oscillograph;
S6. extract the voltage signal that measures of oscillograph detection coil obtained, and with voltage signal when zero defect into
Row compares, and can whether there is defect in judgement material;By compared with calibration curve, it may be determined that the actual depth of defect.
Further, electric current I in small excitation coil2With electric current I in big excitation coil1Ratio be I2/I1=2-6, phase difference
For 120-170 degree.
The main configuration parameters of probe include that the exciting current of coil dimension, driving frequency and two excitation coils is big
Small scale and phase difference.Exciting current size, phase difference and excitation in two form excitation coils in the utility model
The cooperation of frequency directly affects the size that penetration depth is vortexed in material.Different frequency, size exciting current in depth of material
Eddy Distribution caused by direction is different, and the eddy current that generation is incuded in exciting current size and material is linear,
By adjusting the size and phase difference of exciting current, makes material surface vortex density zero, that is, can effectively reduce vortex
Kelvin effect.Generated vortex density is larger on the surface of the material for high frequency, and low frequency is then exactly the opposite.
The utility model preferably takes two biggish rectangular vortex coils as excitation coil, 16 lesser round whirlpools
Streamline circle is as detection coil, acquisition testing signal.Nested inside and outside two form excitation coils, detection coil is located at outer rectangular lines
The following position directly of circle, top and surrounding are surrounded by magnetic shield shell.It is small to swash when the pumping signal of two frequencies motivates simultaneously
2-6 times that size of current in coil is size of current in big excitation coil is encouraged, phase difference is maintained at 120-170 degree, lacks to depth
Falling into can be obtained preferable detection effect.
The principles of the present invention are:
The utility model, using nesting inside and outside two form excitation coils, swashs to increase vortex penetration depth at two
It encourages the sinusoidal excitation current for each leading into the size different frequency different with phase in coil while motivating, it is on the surface of the material and interior
Portion induces vortex contrary, that distribution is different.Successively surface of test piece is carried out using two kinds of orthogonal scanning paths
Scanning twice detects transversal crack and longitudinal crack that may be present in material respectively.The crackle vertical with scanning direction can be
Disturbance voltage signal is generated in detection coil, compared with carrying out processing and voltage signal when the zero defect to disturbance voltage signal,
It can determine position and the size of crackle.The crackle parallel with scanning direction will not generate disturbance voltage letter in detection coil
Number, but itself and scanning path orthogonal can be made, by changing scanning path to avoid that missing inspection situation occurs.The utility model passes through
Excitation parameters appropriate are set, keep the vortex of material surface equivalent reversed, stack result zero, to make material internal depths
Vortex density becomes larger.When the pumping signal of two frequencies motivates simultaneously, it just will appear penetration depth at the specific incentives moment and increase
The case where.By solving the equal nonlinear equation of two excitation signal amplitudes, extracted from voltage tim e- domain detection signal specific
The deep layer Signal of Cracks at moment.By carrying out processing to the induced voltage signal in detection coil and believing with voltage when zero defect
It number is compared, defect can be whether there is in judgement material.By compared with calibration curve, it may be determined that the practical depth of defect
Degree.
The utility model is additionally provided deep zone defect when being motivated using above-mentioned dual frequency array eddy current probe and detects mentioning for signal
Take method, it is characterised in that:
By solving following trigonometric function equation, the time point that material surface vortex density is superposed to zero is obtainedt, the time
PointtTwo excitation amplitude ratios are on double frequency excitation signal graph in i.e. small excitation coil and big excitation coilAgain, contrary
Synchronization two o'clock, at this moment extract detectable voltage signals can be used to crack depth judgement.
,
;
It enables,kThe negative sign "-" of front indicates reverse phase (i.e. difference 180 degree).
Wherein,i 1Withi 2It is the exciting current of big excitation coil and small excitation coil respectively;
f 1Withf 2It is the driving frequency of big excitation coil and small excitation coil respectively;
A 1WithA 2It is the exciting current of big excitation coil and small excitation coil respectivelyi 1Withi 2Amplitude;
, multiple is adjusted for size of current, is exciting current in small excitation coil and big excitation coili 2Withi 1's
AmplitudeWithThe ratio between;
WithIt is the phase of the exciting current of big excitation coil and small excitation coil respectively;
,Be when two excitation coils are motivated respectively with the exciting current of same size and phase
The phase difference of vortex density caused by material surface;
tIt is the time.
When extracting detectable voltage signals, for the vortex density superposition for incuding the two exciting currents on the surface of the material
It is zero, needs to adjust the amplitude and phase of exciting current simultaneously.Work as satisfactioni 2Amplitude bei 1AmplitudekTimes and the two phase
When opposite, the vortex density that just the two can be made to be induced on the surface of the material is equal in magnitude, contrary and to offset be zero, together
When material internal vortex density superposition the sum of be not zero, be exactly the letter of material internal vortex field detected by such detection coil
Number, so exciting currenti 1Withi 2Condition should be met:。
The utility model has the beneficial effects that
1, a kind of dual frequency array eddy current probe of the utility model, detection efficiency is high, detects depth depth, high resolution, spirit
Sensitivity is good;By appropriately designed coil dimension, large area plate and complex parts can be carried out in a very short period of time complete
Inspection.By adjusting the driving frequency and exciting current of two excitation coils, the defects detection information of different depth can get.
2, the utility model eliminates excitation field pair using the circular coil with magnetic shield shell as detecting element
The interference for detecting signal, improves the sensitivity of detection coil.
3, the utility model is motivated simultaneously using double frequency sinusoidal signal, generates the biggish uniform whirlpool of penetration depth in the material
Stream can get the biggish deep torn grain of signal-to-noise ratio and detect signal.Standard osmotic depth, double frequency are calculated on the basis of vortex density peak value
The penetration depth of Array eddy-current probe can reach 3 times of conventional uniform eddy current probe or so, and contrast and experiment shows using double
The detection of frequency Array eddy-current probe, the penetration depth maximum in SUS304 stainless steel can reach 16mm or so.
4, the extraction side of deep zone defect detection signal when the utility model provides double frequency sinusoidal alternating current while motivating
Method.
5, compared with using round excitation coil double frequency excitation eddy current probe in the prior art, the utility model has used square
Shape coil is deeper to generate reversed vortex superposition penetration depth, and form excitation coil to the magnetic field of circle detection coil without shadow
It rings, noise is small in detection signal, and detection signal is easy to measure, sensitiveer;Simultaneously as two square coils nest together, account for
It is small with space, so probe size is relatively small.
Detailed description of the invention
Fig. 1 is dual frequency array eddy current probe installation diagram described in the utility model embodiment 1;
Fig. 2 is dual frequency array eddy current probe detection scheme figure described in the utility model embodiment 2;
Fig. 3 is the double frequency excitation signal graph in the described two excitation coils of the utility model embodiment 2;
Fig. 4 is the voltage detection signal figure obtained described in the utility model embodiment 2 by detection coil;
Fig. 5 is dual frequency array eddy current probe described in the utility model embodiment 3 in two kinds of driving frequency groups of 10kHz, 5kHz
The linear relationship chart of vortex density and penetration depth when conjunction;
Fig. 6 is the probe of routine single-frequency uniform turbulence described in the utility model embodiment 3 and embodiment 4 in 5kHz driving frequency
The linear relationship chart of vortex density and penetration depth when excitation;
Fig. 7 is the probe of routine single-frequency uniform turbulence described in the utility model embodiment 3 in the excitation of 10kHz driving frequency
The linear relationship chart of vortex density and penetration depth;
Fig. 8 is dual frequency array eddy current probe described in the utility model embodiment 4 in two kinds of driving frequency groups of 20kHz, 5kHz
The linear relationship chart of vortex density and penetration depth when conjunction;
Fig. 9 is the probe of routine single-frequency uniform turbulence described in the utility model embodiment 4 in the excitation of 20kHz driving frequency
The linear relationship chart of vortex density and penetration depth;
Components, position and number in figure:
The big excitation coil of 1-;The small excitation coil of 2-;Skeleton is fixed in 3-;4- detection coil;5- shielding case outer cylinder;6- shielding
Cover top cover;7- wrapping post;8- rectangle mounting groove;9- mounting groove top cover;10- first outlet hole;11- scanning frame mounting hole;12- second goes out
String holes;13- detection coil lead outlet hole.
Specific embodiment
The technical solution of the utility model is described in detail with reference to the accompanying drawing, but the content of the utility model is not
It is confined to this.
Embodiment 1:
As shown in Figure 1, a kind of dual frequency array eddy current probe, the rectangle including exciting element, detecting element and both ends open
Mounting groove 8, the exciting element and detecting element are mounted in rectangle mounting groove 8, and detecting element is located at below exciting element, and two
Person's axis is vertical;The mounting groove top cover 9 detachably installed is additionally provided on the rectangle mounting groove 8;It is characterized by: described swash
Encouraging element includes big excitation coil 1, small excitation coil 2 and interior fixed skeleton 3;The small excitation coil 2 is wound on interior fixed bone
On frame 3, the big excitation coil 1 is wound on small excitation coil 2, by big excitation coil 1, small excitation coil 2 and interior fixed bone
The exciting element entirety nesting that frame 3 is constituted is mounted in the rectangle mounting groove 8, axial and 8 opening direction one of rectangle mounting groove
It causes;
The detecting element has 16, arranges in 4 × 4 matrixes;Each detecting element includes 1 detection coil 4,1 screen
Cover the wrapping post 7 of shielding case top cover 6,1 of cover outer cylinder 5,1;The wrapping post 7 is arranged in array, and is vertically fixedly mounted on described
On 8 slot bottom of rectangle mounting groove;The shielding case outer cylinder 5 is in hollow tube-shape and both ends open;The shielding case top cover 6 is in the form of sheets;
The detection coil 4, shielding case outer cylinder 5 are sequentially sleeved on wrapping post 7, and the shielding case top cover 6 is removably mounted at shielding case
5 top of outer cylinder;The shielding case outer cylinder 5 and shielding case top cover 6 collectively form the shielding shell of detection coil 4;All shielding cases
6 upper surface of top cover flushes.
The big excitation coil 1 and small excitation coil 2 are rectangular vortex coil.
The detection coil 4 is circular vortex coil, and diameter is less than the width of small excitation coil 2, in capturing material
Signal of Cracks.
The big excitation coil 1, small excitation coil 2 and interior 3 axis of fixed skeleton are overlapped, both ends end face respectively with rectangle
8 two ports of mounting groove flush.
The detection coil 4 is arranged in matrix, positioned at the following position directly of big excitation coil 1.
1 lower surface of big excitation coil is contacted with 6 upper surface of shielding case top cover.
The shielding case outer cylinder 5, detection coil 4 and 6 axis of shielding case top cover are overlapped.
The detection coil lead outlet hole 13 being pierced by for 4 lead of detection coil is provided on 5 cylinder of shielding case outer cylinder.
The rectangle mounting groove 8, mounting groove top cover 9, wrapping post 7 and interior fixed skeleton 3 are made of PVC material.
The 8 two sidewalls upper end of rectangle mounting groove is provided with two symmetrical conduits, for installing the mounting groove top cover
9。
The big excitation coil 1, small excitation coil 2 and detection coil 4 are formed by enameled wire coiling.
There are two scanning frame mounting holes 11 for setting on the mounting groove top cover 9, are symmetrically distributed on mounting groove top cover 9, use
In by a kind of dual frequency array eddy current probe integral installation described in the utility model on scanning frame.
The lead being additionally provided on the mounting groove top cover 9 for big excitation coil 1, small excitation coil 2 is pierced by rectangle installation
The first outlet hole 10 of slot 8 and the second outlet hole 12 that rectangle mounting groove 8 is pierced by for the lead of detection coil 4.
It is different that different frequency, size of current difference, phase is respectively adopted in the big excitation coil 1 and small excitation coil 2
Sinusoidal alternating current is motivated.
By a kind of 1 installation diagram of dual frequency array eddy current probe of gained of embodiment, Fig. 1 is seen.
Embodiment 2:
As shown in Fig. 2, on the basis of embodiment 1, it is a kind of to utilize a kind of above-mentioned dual frequency array eddy current probe to deep torn grain
The method that defect is detected, it is characterised in that: the following steps are included:
S1. it probe assembly: carries out by the following method:
Firstly, wrapping post 7 is vertically fixedly mounted on 8 slot bottom of rectangle mounting groove, it will test 4 sets of coil in wrapping post 7
On, then by 5 sets of shielding case outer cylinder in 4 outside of detection coil, then, will test the lead of coil 4 first by 5 cylinder of shielding case outer cylinder
On detection coil lead outlet hole 13 be pierced by, finally 5 top of shielding case outer cylinder install shielding case top cover 6, with method complete institute
There is the assembling of detecting element.Each detection coil 4 and its corresponding shielding case outer cylinder 5,6 center of shielding case top cover should be kept coaxially,
All 6 upper surfaces of shielding case top cover flush.
Secondly, small excitation coil 2 is wound on interior fixed skeleton 3, then big excitation coil 1 is wound on small excitation coil
On 2, then it is installed on the exciting element entirety being made of interior fixed skeleton 3, small excitation coil 2 with big excitation coil 1 is nested
In rectangle mounting groove 8, it is located at the surface of detecting element, and the lower surface of big excitation coil 1 and shielding case top cover 6 is upper
Surface is in contact.Big excitation coil 1, small excitation coil 2 and interior 3 axis of fixed skeleton are overlapped, both ends end face respectively with rectangle
8 two ports of mounting groove flush, and center line keeps coaxial, and relative position is kept to fix.
Then, mounting groove top cover 9 is installed on rectangle mounting groove 8;The lead that will test coil 4 passes through mounting groove top cover again
Second outlet hole 12 on 9 is pierced by rectangle mounting groove 8;By the lead of big excitation coil 1 and small excitation coil 2 by mounting groove top cover
First outlet hole 10 on 9 is pierced by rectangle mounting groove 8.
Finally, entire probe is mounted on scanning frame by scanning frame mounting hole 11.
S2. the lead of big excitation coil 1 and small excitation coil 2 is connected to two AC power sources, will test coil 4
Coil lead is connected to oscillograph, to apply pumping signal, to receive testing result.
S3. different frequency, size of current difference, phase are continually fed into big excitation coil 1 and small excitation coil 2 not
Same steady-state sine alternating current is motivated;Wherein, electric current I in small excitation coil 22With electric current I in big excitation coil 11Ratio
Example is I2/I1=2-6, phase difference are 120-170 degree.
S4. probe is made to carry out scanning on material for test surface;When scanning, as shown in Fig. 2, using probe scanning path phase
Mutually vertical scanning mode twice detects surface of test piece.Disturbance of the vortex field of fault location by defect, passes through disturbance
Magnetic field is fed back into detection coil 4 by defect information.
S5. the detection signal that will test in coil 4 is input in oscillograph.
S6. extract the voltage signal that measures of oscillograph detection coil 4 obtained, and with voltage signal when zero defect
It is compared, defect can be whether there is in judgement material;By compared with calibration curve, it may be determined that the actual depth of defect.
In step S6, the extracting method of signal is detected specifically:
By solving following trigonometric function equation, the time point that material surface vortex density is superposed to zero is obtainedt, the time
PointtTwo excitation amplitude ratios are on double frequency excitation signal graph in i.e. small excitation coil 2 and big excitation coil 1Again, direction phase
The two o'clock of anti-synchronization extracts voltage inspection as shown in the double frequency excitation signal graph in two excitation coils of Fig. 3 at this moment
Signal is surveyed, shown in the voltage detection signal figure obtained such as Fig. 4 as detection coil 4, extracts detectable voltage signals at this moment
Judge for crack depth.
,
;
It enables,kThe negative sign "-" of front indicates reverse phase (i.e. difference 180 degree).
Wherein,i 1Withi 2It is the exciting current of big excitation coil 1 and small excitation coil 2 respectively;
f 1Withf 2It is the driving frequency of big excitation coil 1 and small excitation coil 2 respectively;
A 1WithA 2It is the exciting current of big excitation coil 1 and small excitation coil 2 respectivelyi 1Withi 2Amplitude;
, multiple is adjusted for size of current, is exciting current in small excitation coil 2 and big excitation coil 1i 2Withi 1
AmplitudeWithThe ratio between;
WithIt is the phase of the exciting current of big excitation coil 1 and small excitation coil 2 respectively;
,Be when two excitation coils are motivated respectively with the exciting current of same size and phase
The phase difference of vortex density caused by material surface;
tIt is the time.
When extracting detectable voltage signals, for the vortex density superposition for incuding the two exciting currents on the surface of the material
It is zero, needs to adjust the amplitude and phase of exciting current simultaneously.Work as satisfactioni 2Amplitude bei 1AmplitudekTimes and the two phase
When opposite, the vortex density that just the two can be made to be induced on the surface of the material is equal in magnitude, contrary and to offset be zero, together
When material internal vortex density superposition the sum of be not zero, detected by such detection coil 4 be exactly material internal vortex field
Signal, so exciting currenti 1Withi 2Condition should be met:。
Embodiment 3:
Penetration depth when detecting for verifying dual frequency array eddy current probe to heavy wall deep torn grain defect is normal better than corresponding
Single-frequency uniform turbulence probe is advised, on the basis of embodiment 2, to 304 austenitic stainless steel test specimens, using two kinds of 10kHz, 5kHz
Driving frequency carries out the penetration depth comparative experiments of conventional single-frequency uniform turbulence probe and dual frequency array eddy current probe.
1. tested using dual frequency array eddy current probe, the electric current of 5kHz, 1A are inputted into big excitation coil 1, to
The electric current of 1kHz, 4A are inputted in small excitation coil 2;The configuration parameter of dual frequency array eddy current probe, detection method and result are specific
It is as follows.
A. configuration parameter
1. big 1 basic size of excitation coil: the long L in sectionx1=50mm, axial long Ly1=50mm, the high L in sectionz1=9mm, thick Δ
t1=1mm;
Small 2 basic size of excitation coil: the long L in sectionx2=48mm, axial long Ly2=50mm, the high L in sectionz2=7mm, thick Δ t2=
1mm;
2. the driving frequency of big excitation coil 1 and small excitation coil 2 is respectively as follows:f 1 =10kHzAnd f 2 =5kHz;
3. the exciting current size in big excitation coil 1 and small excitation coil 2 is respectively as follows:I 1 =1AAnd I 2 =2A,
Exciting current phase difference: 170 °;
4. 4 basic size of detection coil: outer radius ro3=1.6mm, inside radius ri3=0.6mm, height hC3=0.8mm;
5. 5 basic size of shielding case outer cylinder: outer radius ro4=1.8mm, inside radius ri4=1.6mm, height hC4=0.8mm;
6. 6 basic size of shielding case top cover: outer radius ro5=1.8mm, thickness deltat t5=0.2mm;
7. detection coil 4 center is away from s=4.6mm.
B. detection method:
As shown in Fig. 2, being detected according to the method in embodiment 2.
C. testing result:
By vortex density of the 3 gained dual frequency array eddy current probe of embodiment when two kinds of driving frequencies of 10kHz, 5kHz combine
With the linear relationship chart of penetration depth, Fig. 5 is seen, can be calculated by curve in Fig. 5, use 10kHz and 5kHz driving frequency group
When conjunction, penetration depth can achieve 15.6mm.
2. only the one big excitation coil 1 of installation and detection coil 4, do not install small excitation on the basis of Examples 1 and 2
Coil 2, shielding case outer cylinder 5 and shielding case top cover 6 obtain conventional single-frequency uniform turbulence probe, are tested.Using single frequency excitation
When rectangular vortex detection probe is tested, the electric current of 10kHz, 1A and the electricity of 5kHz, 1A are successively inputted into big excitation coil 1
Stream;Method and result are specific as follows:
1. inputting frequency into big excitation coil 1f 1=10kHz, electric currentI 1The steady-state sine exciting current of=1A, using with
Identical method is tested when installing big excitation coil 1 with small excitation coil 2 simultaneously;Gained routine single-frequency uniform turbulence probe
The linear relationship chart of vortex density and penetration depth in the excitation of 10kHz driving frequency, is shown in Fig. 7;It can be calculated by curve in Fig. 7
It obtains, penetration depth when 10kHz unifrequency motivates is 5.3mm;
2. inputting frequency into excitation coil 1f 2=5kHz, electric currentI 2The steady-state sine exciting current of=1A, using with installation
Identical method is tested when two groups of excitation coils 1;Gained routine single-frequency uniform turbulence probe is motivated in 5kHz driving frequency
When vortex density and penetration depth linear relationship chart, see Fig. 6.It can be calculated by curve in Fig. 6, the excitation of 5kHz unifrequency
When penetration depth be 6.4mm.
3. double frequency excitation and single frequency excitation testing result compare:
Penetration depth and conventional single-frequency uniform whirlpool of the dual frequency array eddy current probe when 10kHz and 5kHz driving frequency combines
The comparison of stream probe resulting penetration depth when two kinds of driving frequencies of 10kHz and 5kHz motivate respectively, is shown in Table 1:
It can be seen from the above result that infiltration is deep using dual frequency array eddy current probe when 10kHz and 5kHz driving frequency combines
It spends up to 15.6mm, is greater than corresponding unifrequency and motivates gained penetration depth respectively, be the 2.44 of conventional uniform eddy current probe respectively
Times and 2.94 times.
Embodiment 4:
It is better than further to verify penetration depth when dual frequency array eddy current probe detects heavy wall deep torn grain defect
Corresponding conventional single-frequency uniform turbulence probe, on the basis of embodiment 2, to 304 austenitic stainless steel test specimens, is further used
Two kinds of driving frequencies of 20kHz, 5kHz carry out the penetration depth pair of conventional single-frequency uniform turbulence probe and dual frequency array eddy current probe
Than experiment.
1. tested using dual frequency array eddy current probe, the electric current of 20kHz, 1A are inputted into big excitation coil 1,
The electric current of 5kHz, 2.7A are inputted into small excitation coil 2;Configuration parameter, detection method and the result of dual frequency array eddy current probe
It is specific as follows.
A. configuration parameter
1. big 1 basic size of excitation coil: the long L in sectionx1=50mm, axial long Ly1=50mm, the high L in sectionz1=9mm, thick Δ
t1=1mm;
Small 2 basic size of excitation coil: the long L in sectionx2=48mm, axial long Ly2=50mm, the high L in sectionz2=7mm, thick Δ t2=
1mm;
2. the driving frequency of big excitation coil 1 and small excitation coil 2 is respectively as follows:f 1=20kHzAnd f 2=5kHz;
3. the exciting current size in big excitation coil 1 and small excitation coil 2 is respectively as follows:I 1=1AAnd I 2=2.7A,
Exciting current phase difference: 160 °;
4. 4 basic size of detection coil: outer radius ro3=1.6mm, inside radius ri3=0.6mm, height hC3=0.8mm;
5. 5 basic size of shielding case outer cylinder: outer radius ro4=1.8mm, inside radius ri4=1.6mm, height hC4=0.8mm;
6. 6 basic size of shielding case top cover: outer radius ro5=1.8mm, thickness deltat t5=0.2mm;
7. detection coil 4 center is away from s=4.6mm.
B. detection method:
As shown in Fig. 2, being detected according to the method in embodiment 2.
C. testing result:
By vortex density of the 3 gained dual frequency array eddy current probe of embodiment when two kinds of driving frequencies of 20kHz, 5kHz combine
With the linear relationship chart of penetration depth, Fig. 8 is seen, can be calculated by curve in Fig. 8, use 20kHz and 5kHz driving frequency group
When conjunction, penetration depth can achieve 13.5mm.
2. only installing big excitation coil 1 and detection coil 4 on the basis of Examples 1 and 2, not installing small excitation coil
2, shielding case outer cylinder 5 and shielding case top cover 6 obtain conventional single-frequency uniform turbulence probe, are tested.It is uniform using conventional single-frequency
When eddy current probe is tested, the electric current of 20kHz, 1A and the electric current of 5kHz, 1A are successively inputted into big excitation coil 1;Method
And result is specific as follows.
B. detection method and result:
1. inputting frequency into big excitation coil 1f 1=20kHz, electric currentI 1The steady-state sine exciting current of=1A, using with
Identical method is tested when installing big excitation coil 1 with small excitation coil 2 simultaneously;Gained routine single-frequency uniform turbulence probe
The linear relationship chart of vortex density and penetration depth in the excitation of 20kHz driving frequency, is shown in Fig. 9;It can be calculated by curve in Fig. 9
It obtains, penetration depth when 20kHz unifrequency motivates is 4.8mm;
2. inputting frequency into excitation coil 1f 2=5kHz, electric currentI 2The steady-state sine exciting current of=1A, using with installation
Identical method is tested when two groups of excitation coils 1;Gained routine single-frequency uniform turbulence probe is motivated in 5kHz driving frequency
When vortex density and penetration depth linear relationship chart, see Fig. 6.It can be calculated by curve in Fig. 6, the excitation of 5kHz unifrequency
When penetration depth be 6.4mm.
3. double frequency excitation and single frequency excitation testing result compare:
Penetration depth and conventional single-frequency uniform whirlpool of the dual frequency array eddy current probe when 20kHz and 5kHz driving frequency combines
The comparison of stream probe resulting penetration depth when two kinds of driving frequencies of 20kHz and 5kHz motivate respectively, is shown in Table 2:
It can be seen from the above result that infiltration is deep using dual frequency array eddy current probe when 20kHz and 5kHz driving frequency combines
It spends up to 13.5mm, is greater than corresponding unifrequency and motivates gained penetration depth respectively, be 2.1 times of conventional uniform eddy current probe respectively
With 2.81 times.
The above is only the preferred embodiment of the utility model, not to limit the interest field of the utility model.
Technical solution that any interest field for being covered with the application the scope of the patents is implemented any is familiar with those skilled in the art
Member, the scheme of many possible changes and modifications is made using the method content of the disclosure above, belongs to the guarantor of the utility model
Protect range.
Claims (10)
1. a kind of dual frequency array eddy current probe, the rectangle mounting groove (8) including exciting element, detecting element and both ends open, institute
It states exciting element and detecting element is mounted in rectangle mounting groove (8), detecting element is located at below exciting element, and the two axis hangs down
Directly;The mounting groove top cover (9) detachably installed is additionally provided on the rectangle mounting groove (8);It is characterized by: the driver element
Part includes big excitation coil (1), small excitation coil (2) and interior fixed skeleton (3);The small excitation coil (2) is wound on interior solid
Determine on skeleton (3), the big excitation coil (1) is wound on small excitation coil (2), by big excitation coil (1), small excitation coil
(2) nested with the exciting element entirety that interior fixed skeleton (3) is constituted to be mounted in the rectangle mounting groove (8), axial direction and rectangle
Mounting groove (8) opening direction is consistent;
The detecting element has n2A, wherein n any one integer between 2-6, each detecting element include 1 detection coil
(4), 1 shielding case outer cylinder (5), 1 shielding case top cover (6), 1 wrapping post (7);The wrapping post (7) is arranged in array, and hangs down
It is directly fixedly mounted on rectangle mounting groove (8) slot bottom;The shielding case outer cylinder (5) is in hollow tube-shape and both ends open;Institute
State detection coil (4), shielding case outer cylinder (5) is sequentially sleeved on wrapping post (7), shielding case top cover (6) is removably mounted at shielding
Cover outer cylinder (5) top;The shielding case outer cylinder (5) and shielding case top cover (6) collectively form the shielding shell of detection coil (4);
All shielding case top cover (6) upper surfaces flush.
2. a kind of dual frequency array eddy current probe as described in claim 1, it is characterised in that: the big excitation coil (1) and small
Excitation coil (2) is rectangular vortex coil.
3. a kind of dual frequency array eddy current probe as claimed in claim 2, it is characterised in that: the detection coil (4) is circle
Eddy current coil, diameter are less than the width of small excitation coil (2).
4. a kind of dual frequency array eddy current probe as claimed in claim 3, it is characterised in that: the big excitation coil (1) is cut
The long L in facex1=50mm, axial long Ly1=50mm, the high L in sectionz1=9mm, thick Δ t1The section of=1mm, the small excitation coil (2) are long
Lx2=48mm, axial long Ly2=50mm, the high L in sectionz2=7mm, thick Δ t2=1mm, the outer radius r of the detection coil (4)o3=
1.6mm, inside radius ri3=0.6mm, high hc3=0.8mm。
5. a kind of dual frequency array eddy current probe as described in claim 1, it is characterised in that: n=4.
6. a kind of dual frequency array eddy current probe as described in claim 1, it is characterised in that: the big excitation coil (1) small is swashed
It encourages coil (2) and interior fixed skeleton (3) axis is overlapped, both ends end face is flushed with (8) two ports of rectangle mounting groove respectively.
7. a kind of dual frequency array eddy current probe as described in claim 1, it is characterised in that: the detection coil (4) is in array
Arrangement is located at the underface of big excitation coil (1);
Big excitation coil (1) lower surface is contacted with shielding case top cover (6) upper surface;
The shielding case outer cylinder (5), detection coil (4) and shielding case top cover (6) axis are overlapped.
8. a kind of dual frequency array eddy current probe as described in claim 1, it is characterised in that: the rectangle mounting groove (8), installation
Groove top lid (9), wrapping post (7) and interior fixed skeleton (3) are made of PVC material;
The big excitation coil (1), small excitation coil (2) and detection coil (4) are formed by enameled wire coiling.
9. a kind of dual frequency array eddy current probe as described in claim 1, it is characterised in that: set on the mounting groove top cover (9)
It is equipped with multiple scanning frame mounting holes (11).
10. a kind of dual frequency array eddy current probe as described in claim 1, it is characterised in that: on the mounting groove top cover (9) also
It is provided with first outlet hole (10) and the confession that rectangle mounting groove (8) is pierced by for the lead of big excitation coil (1), small excitation coil (2)
The lead of detection coil (4) is pierced by the second outlet hole (12) of rectangle mounting groove (8).
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