Aviation Metal Component Defect Detection Imaging Probe and Method

Abstract

The present invention discloses an imaging probe and method for detecting defects in aviation metal components. The probe includes a set of coaxially fixed disk-shaped excitation coils, an axial magnetic field sensor, and a balancing device. The set of disk-shaped excitation coils consists of a solid inner disk-shaped excitation coil and an outer disk-shaped excitation coil nested outside it. The diameter of the enameled copper wire used to wind the two disk-shaped excitation coils is equal, and the height and radial thickness of the two disk-shaped coils are the same. The axial magnetic field sensor is closely attached to the bottom center of the solid disk-shaped excitation coil for measuring the magnetic induction intensity along the axis of the excitation coil. The balancing device can ensure that the probe can be closely attached to the aviation metal component. The present invention also provides a detection imaging method for the above probe, which can quickly and accurately detect different-sized defects in aviation metal components and has important engineering application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of non-destructive testing, and relates to a defect detection imaging probe and method for aviation metal components. Background Art

[0002] At present, aviation metals are widely used in aircraft structures. The advantages of aviation metal components (such as aluminum alloys, titanium alloys, etc.) are their high specific strength and specific stiffness, which can effectively reduce the structural weight of aircraft, improve flight performance and increase economic benefits.

[0003] Due to the complex service environment, various types of defects are likely to occur in aviation metal components during service, which will reduce the service life of aviation metal components and seriously affect flight safety. Therefore, it is of great significance to image the defects of aviation metal components. At present, single excitation signals are mostly used for pulsed eddy current detection of aviation metal component defects, and there are still blanks in the research and engineering applications of using composite excitation signals for high-precision imaging of aviation metal component defects. Summary of the Invention

[0004] In order to solve the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a defect detection imaging probe and method for aviation metal components, which can quickly and accurately image the defects of aviation metal components and have important engineering application value.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A defect detection imaging probe for aviation metal components includes an inner disc-shaped excitation coil (1) and an outer disc-shaped excitation coil (2) coaxially fixed, an axial magnetic field sensor (3) coaxially fixed on the axis of symmetry of the inner disc-shaped excitation coil (1), and a balancing device (4) fixed below the outer disc-shaped excitation coil (2); the axial magnetic field sensor (3) is used to measure the axial magnetic induction intensity of the inner disc-shaped excitation coil (1); the annular balancing device (4) is coaxially fixed to the outer disc-shaped excitation coil (2).

[0007] Preferably, the outer diameter Φ of the outer disc-shaped excitation coil (2) is twice the outer diameter of the inner disc-shaped excitation coil (1), and the outer disc-shaped excitation coil (2) and the inner disc-shaped excitation coil (1) have the same height and the same number of coil turns. The balancing device (4) is circular and has the same height as the axial magnetic field sensor (3).

[0008] A defect detection imaging method for aviation metal components includes the establishment of a defect scanning feature matrix for aviation metal components and the imaging of defects of aviation metal components;

[0009] (1) The establishment of a defect scanning feature matrix for aviation metal components, and the specific method is as follows: ​

[0010] Connect a signal generator, a power amplifier, the said probe, a signal amplifier, a filter, a data acquisition card and a computer in sequence to form a detection system; the period of the excitation signal acting on the inner disk-shaped excitation coil (1) is T, the current amplitude is A1 from 0 to 0.25T and from 0.5T to 0.75T, and the current amplitude is 0 from 0.25T to 0.5T and from 0.75T to T; the period of the excitation signal acting on the outer disk-shaped excitation coil (2) is T, the current amplitude is A1 from 0.5T to 0.75T, and the current amplitude is 0 from 0 to 0.5T and from 0.75T to T;

[0011] Closely attach the said probe to the surface of the defect-free area of the aviation metal component, the detection system works, the electrical signal generated by the axial magnetic field sensor (3) affected by the magnetic induction intensity at its spatial position is processed by the signal amplifier and the filter, and then the computer obtains the detection signal S0 with a period of T through the data acquisition card, and uses it as the reference signal;

[0012] Closely attach the said probe to the area to be measured of the aviation metal component and conduct a scan with a step size of l0. The scan area is a rectangular scan area with lengths and widths of m×l0 and n×l0 respectively, and obtain the scan signal S 1,1 ,S 1,2 ,S 1,3 ,S 1,4 ,…,S m,n-2 ,S m,n-1 ,S m,n ,Subtract the above scan signal from the reference signal S0 to obtain the corresponding differential signal D 1,1 ,D 1,2 ,D 1,3 ,D 1,4 ,…,D m,n-2 ,D m,n-1 ,D m,n ;Extract the 0 - 0.5T part of each differential signal to obtain the 0 - 0.5T differential signal Da 1,1 ,Da 1,2 ,Da 1,3 ,Da 1,4 ,…,Da m,n-2 ,Da m,n-1 ,Da m,n ,Extract the 0.5T - T part of each differential signal to obtain the 0.5T - T differential signal Db 1,1 ,Db 1,2 ,Db 1,3 ,Db 1,4 ,…,Db m,n-2 ,Db m,n-1 ,Db m,n ;Extract each 0 - 0.5T differential signal Da 1,1 ,Da 1,2 ,Da1,3 , Da 1,4 , …, Da m,n-2 , Da m,n-1 , Da m,n , the peak value of, and obtain Pa 1,1 , Pa 1,2 , Pa 1,3 , Pa 1,4 , …, Pa m,n-2 , Pa m,n-1 , Pa m,n , and then obtain a 0 - 0.5T two - dimensional scanning feature matrix ka of size m×n; extract each 0.5T - T differential signal Db 1,1 , Db 1,2 , Db 1,3 , Db 1,4 , …, Db m,n-2 , Db m,n-1 , Db m,n , the peak value of, and obtain Pb 1,1 , Pb 1,2 , Pb 1,3 , Pb 1,4 , …, Pb m,n-2 , Pb m,n-1 , Pb m,n , and then obtain a 0.5T - T two - dimensional scanning feature matrix kb of size m×n;

[0013] (2) Defect imaging of aviation metal components, the specific method is as follows:

[0014] Calculate the gradient value of each element of the 0 - 0.5T two - dimensional scanning feature matrix ka along the longitudinal direction, and respectively obtain Pza 1,1 , Pza 1,2 , Pza 1,3 , Pza 1,4 , …, Pza m,n-2 , Pza m,n-1 , Pza m,n , and extract its maximum value Pzam; calculate the gradient value of each element of the 0 - 0.5T two - dimensional scanning feature matrix ka along the horizontal direction, and respectively obtain Pha 1,1 , Pha 1,2 , Pha 1,3 , Pha 1,4 , …, Pha m,n-2 , Pha m,n-1 , Pha m,n, extract its maximum value Pham; extract the maximum element Pam in the two-dimensional scanning feature matrix ka from 0 to 0.5T; perform calculation processing on all elements of the two-dimensional scanning feature matrix ka from 0 to 0.5T to obtain the two-dimensional scanning feature processed matrix kat after 0 to 0.5T, and any element kati,j in the two-dimensional scanning feature processed matrix kat after 0 to 0.5T = ((Pza i,j / Pzam) 2 +(Pha i,j / Pham) 2 ) 1 / 2 / ((Pza i,j / Pzam) 2 +(Pha i,j / Pham) 2 +(Pa i,j / Pam) 2 +1) 1 / 2 ;

[0015] Calculate the gradient value of each element of the two-dimensional scanning feature matrix kb along the longitudinal direction from 0.5T to T, and obtain Pzb 1,1 , Pzb 1,2 , Pzb 1,3 , Pzb 1,4 , …, Pzb m,n-2 , Pzb m,n-1 , Pzb m,n , and extract its maximum value Pzbm; calculate the gradient value of each element of the two-dimensional scanning feature matrix kb along the horizontal direction from 0.5T to T, and obtain Phb 1,1 , Phb 1,2 , Phb 1,3 , Phb 1,4 , …, Phb m,n-2 , Phb m,n-1 , Phb m,n , extract its maximum value Phbm; extract the maximum element Pbm in the two-dimensional scanning feature matrix kb from 0.5T to T; perform calculation processing on all elements of the two-dimensional scanning feature matrix kb from 0.5T to T to obtain the two-dimensional scanning feature processed matrix kbt after 0.5T to T, and any element kbti,j in the two-dimensional scanning feature processed matrix kbt after 0.5T to T = ((Pzb i,j / Pzbm) 2 +(Phb i,j / Phbm) 2 ) 1 / 2 / ((Pzb i,j / Pzbm) 2 +(Phb i,j / Phbm) 2 +(Pb i,j / Pbm)2 +1) 1 / 2 ;

[0016] The Canny algorithm is used to perform edge recognition on the image formed by the matrix kat after processing the two-dimensional scanning features from 0 to 0.5T, obtaining the 0 - 0.5T edge recognition matrix katc. The elements with a value of 1 in the 0 - 0.5T edge recognition matrix katc represent the image edges. The elements located within the image edges are assigned a value of 1 to obtain the 0 - 0.5T image matrix katd;

[0017] The Canny algorithm is used to perform edge recognition on the image formed by the matrix kbt after processing the two-dimensional scanning features from 0.5T to T, obtaining the 0.5T - T edge recognition matrix kbtc. The elements with a value of 1 in the 0.5T - T edge recognition matrix kbtc represent the image edges. The elements located within the image edges are assigned a value of 1 to obtain the 0.5T - T image matrix kbtd;

[0018] Calculate the sum of all elements of the 0 - 0.5T image katd matrix as katds, and calculate the sum of all elements of the 0.5T - T image matrix kbtd as kbtds. If katds + kbtds ≥ 0.5πΦ 2 , it is considered that the morphology of the defect in the detection area is the grayscale image shown by the 0.5T - T image matrix kbtd; if katds + kbtds < 0.5πΦ 2 then it is considered that the morphology of the defect in the detection area is the grayscale image shown by the 0 - 0.5T image matrix katd.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. The probe of the present invention is in a dual - coil composite excitation mode, which can effectively respond to defects of different sizes, effectively improving the sensitivity of defect detection, and the detection signal contains richer defect information.

[0021] 2. The method of the present invention first uses the probe of the present invention to establish the pulse eddy current signal scanning feature matrix of the aviation metal component; when using the probe of the present invention to detect the aviation metal component to be measured, the imaging method proposed by the present invention can perform high - precision imaging on defects of different sizes. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic diagram of the probe structure of the present invention.

[0023] Figure 2 is the excitation signal waveform of the inner - disk excitation coil.

[0024] Figure 3 is the excitation signal waveform of the outer - disk excitation coil.

[0025] Figure 4 It is a block diagram of the detection system.

[0026] Figure 5 It is the detection imaging result of artificial defects on the aviation metal component by applying the present invention. Specific embodiments

[0027] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0028] As Figure 1 shown, the defect imaging probe for the aviation metal component of the present invention includes an inner disk-shaped excitation coil 1 and an outer disk-shaped excitation coil 2 which are coaxially fixed, an axial magnetic field sensor 3 coaxially fixed on the axis of symmetry of the inner disk-shaped excitation coil 1, and a balancing device 4 fixed below the outer disk-shaped excitation coil 2; the outer diameter of the outer disk-shaped excitation coil 2 is twice the outer diameter of the inner disk-shaped excitation coil 1, and the two have the same height; the axial magnetic field sensor 3 is used to measure the axial magnetic induction intensity of the inner disk-shaped excitation coil 1; the annular balancing device 4 is coaxially fixed to the outer disk-shaped excitation coil 2; the outer diameter Φ of the outer disk-shaped excitation coil 2 is twice that of the inner disk-shaped excitation coil 1, and the outer disk-shaped excitation coil 2 and the inner disk-shaped excitation coil 1 have the same height and the same number of coil turns. The balancing device 4 is circular and can ensure that the probe can be closely attached to the aviation metal component. The balancing device 4 and the axial magnetic field sensor 3 have the same height.

[0029] The defect detection imaging method for the aviation metal component of the present invention includes the establishment of a defect scanning feature matrix for the aviation metal component and the defect imaging of the aviation metal component;

[0030] (1) The establishment of the defect scanning feature matrix for the aviation metal component is as follows:

[0031] As Figure 4 shown, the signal generator, power amplifier, probe, signal amplifier, filter, data acquisition card and computer are connected in sequence. The excitation current signal waveforms of the disk-shaped excitation coil 1 and the disk-shaped excitation coil 2 are respectively as Figure 2 and Figure 3 shown.

[0032] The probe is closely attached to the surface of the defect-free area of the aviation metal component. When the detection system works, the electrical signal generated by the axial magnetic field sensor 3 affected by the magnetic induction intensity at its spatial position is processed by the signal amplifier and filter, and then the computer obtains the detection signal S0 with a period of T through the data acquisition card and uses it as the reference signal.

[0033] The probe is closely attached to the area to be detected of the aviation metal component and scanned with a step size of l0. The scanned area is a rectangular scanned area with lengths and widths of m×l0 and n×l0 respectively, and the scanned signal S is obtained1,1 , S 1,2 , S 1,3 , S 1,4 , …, S m,n-2 , S m,n-1 , S m,n , subtract the above scanning signal from the reference signal S0 to obtain the corresponding differential signal D 1,1 , D 1,2 , D 1,3 , D 1,4 , …, D m,n-2 , D m,n-1 , D m,n ; extract the 0 - 0.5T part of each differential signal to obtain the 0 - 0.5T differential signal Da 1,1 , Da 1,2 , Da 1,3 , Da 1,4 , …, Da m,n-2 , Da m,n-1 , Da m,n , extract the 0.5T - T part of each differential signal to obtain the 0.5T - T differential signal Db 1,1 , Db 1,2 , Db 1,3 , Db 1,4 , …, Db m,n-2 , Db m,n-1 , Db m,n ; extract the peaks of each 0 - 0.5T differential signal Da 1,1 , Da 1,2 , Da 1,3 , Da 1,4 , …, Da m,n-2 , Da m,n-1 , Da m,n to obtain Pa 1,1 , Pa 1,2 , Pa 1,3 , Pa 1,4 , …, Pa m,n-2 , Pa m,n-1 , Pa m,n , and then obtain the 0 - 0.5T two - dimensional scanning feature matrix ka of size m×n; extract the peaks of each 0.5T - T differential signal Db 1,1 , Db 1,2 , Db 1,3 , Db 1,4 , …, Db m,n-2 , Db m,n-1 , Db m,n to obtain Pb 1,1 , Pb 1,2 , Pb 1,3 , Pb 1,4 , …, Pbm,n-2 , Pb m,n-1 , Pb m,n , and then obtain a two-dimensional scanning feature matrix kb of size m×n with values ranging from 0.5T to T;

[0034] (2) Defect imaging of aviation metal components, the specific method is as follows:

[0035] Calculate the gradient values of each element of the two-dimensional scanning feature matrix ka from 0 to 0.5T along the longitudinal direction, and respectively obtain Pza 1,1 , Pza 1,2 , Pza 1,3 , Pza 1,4 , …, Pza m,n-2 , Pza m,n-1 , Pza m,n , and extract its maximum value Pzam; calculate the gradient values of each element of the two-dimensional scanning feature matrix ka from 0 to 0.5T along the transverse direction, and respectively obtain Pha 1,1 , Pha 1,2 , Pha 1,3 , Pha 1,4 , …, Pha m,n-2 , Pha m,n-1 , Pha m,n , extract its maximum value Pham; extract the maximum element Pam in the two-dimensional scanning feature matrix ka from 0 to 0.5T; perform calculation processing on all elements of the two-dimensional scanning feature matrix ka from 0 to 0.5T to obtain a processed two-dimensional scanning feature matrix kat from 0 to 0.5T, and for any element kati,j in the processed two-dimensional scanning feature matrix kat from 0 to 0.5T, kati,j = ((Pza i,j / Pzam) 2 +(Pha i,j / Pham) 2 ) 1 / 2 / ((Pza i,j / Pzam) 2 +(Pha i,j / Pham) 2 +(Pa i,j / Pam) 2 +1) 1 / 2 ;

[0036] Calculate the gradient values of each element of the two-dimensional scanning feature matrix kb from 0.5T to T along the longitudinal direction, and respectively obtain Pzb 1,1 , Pzb 1,2 , Pzb 1,3 , Pzb 1,4 , …, Pzb m,n-2 , Pzb m,n-1 , Pzb m,n, and extract its maximum value Pzbm; calculate the gradient values of each element of the 0.5T-T two-dimensional scanning feature matrix kb along the horizontal direction to obtain Phb 1,1 , Phb 1,2 , Phb 1,3 , Phb 1,4 , …, Phb m,n-2 , Phb m,n-1 , Phb m,n , extract its maximum value Phbm; extract the maximum element Pbm in the 0.5T-T two-dimensional scanning feature matrix kb; perform calculation processing on all elements of the 0.5T-T two-dimensional scanning feature matrix kb to obtain the 0.5T-T two-dimensional scanning feature processed matrix kbt, and any element kbti,j in the 0.5T-T two-dimensional scanning feature processed matrix kbt = ((Pzb i,j / Pzbm) 2 +(Phb i,j / Phbm) 2 ) 1 / 2 / ((Pzb i,j / Pzbm) 2 +(Phb i,j / Phbm) 2 +(Pb i,j / Pbm) 2 +1) 1 / 2 ;

[0037] Adopt the Canny algorithm to perform edge recognition on the image composed of the 0-0.5T two-dimensional scanning feature processed matrix kat to obtain the 0-0.5T edge recognition matrix katc. The elements with a value of 1 in the 0-0.5T edge recognition matrix katc represent the image edge. Assign a value of 1 to the elements located within the image edge to obtain the 0-0.5T image matrix katd;

[0038] Adopt the Canny algorithm to perform edge recognition on the image composed of the 0.5T-T two-dimensional scanning feature processed matrix kbt to obtain the 0.5T-T edge recognition matrix kbtc. The elements with a value of 1 in the 0.5T-T edge recognition matrix kbtc represent the image edge. Assign a value of 1 to the elements located within the image edge to obtain the 0.5T-T image matrix kbtd;

[0039] Calculate the sum of all elements of the 0-0.5T image matrix katd as katds, and calculate the sum of all elements of the 0.5T-T image matrix kbtd as kbtds. If katds + kbtds ≥ 0.5πΦ 2 , it is considered that the morphology of the defect in the detection area is the grayscale image shown by the 0.5T-T image matrix kbtd; if katds + kbtds < 0.5πΦ 2It is considered that the morphology of the defects in the detection area is the grayscale image shown by the 0-0.5T image matrix katd.

[0040] Embodiment:

[0041] Using the aviation metal component defect detection imaging probe of the present invention to detect artificial defects of an aviation titanium alloy component, closely attach the probe to the aviation titanium alloy component, and scan it. By using the defect detection imaging method of the present invention, the defect imaging diagram as shown in Figure 5 can be obtained. The black area is the defect imaging diagram obtained from the experiment, and the edge dotted line is the actual contour of the defect.

[0042] From Figure 5 it can be seen that the defect imaging result is very close to the actual size of the defect, and the basic shape of the artificial defect of the aviation titanium alloy component can be accurately depicted. The accuracy of the identified defect area can reach 96%. It can be seen that by using the aviation metal component defect detection imaging probe and method of the present invention, high-precision imaging of aviation metal component defects can be achieved.

Claims

1. An imaging method for detecting defects in aviation metal components, characterized in that: Including the establishment of a defect scanning feature matrix for aviation metal components and defect imaging of aviation metal components; 1) Establishment of a defect scanning feature matrix for aviation metal components, and the specific method is as follows: Connect a signal generator, a power amplifier, an imaging probe for detecting defects in an aviation metal component, a signal amplifier, a filter, a data acquisition card, and a computer in sequence to form a detection system; the period of the excitation signal acting on the inner disk-shaped excitation coil (1) is T , within 0 to 0.25 T , 0.5 T ~0.75 T the current amplitude is A 1, and within 0.25 T ~0.5 T , 0.75 T ~ T the current amplitude is 0 ; The excitation signal period acting on the outer disk type excitation coil (2) is T , at 0.5 T ~0.75 T The current amplitude is A 1, at 0~0.5 T , 0.75 T ~ T The current amplitude is 0 ; The defect detection and imaging probe for aviation metal components includes an inner disk-shaped excitation coil (1) and an outer disk-shaped excitation coil (2) fixedly arranged coaxially, an axial magnetic field sensor (3) fixedly arranged on the axis of symmetry of the inner disk-shaped excitation coil (1), and a balancing device (4) fixed below the outer disk-shaped excitation coil (2); the axial magnetic field sensor (3) is used to measure the axial magnetic induction intensity of the inner disk-shaped excitation coil (1); the balancing device (4) is fixedly arranged coaxially with the outer disk-shaped excitation coil (2); Closely attach the imaging probe for detecting defects of the aviation metal component to the surface of the defect-free area of the aviation metal component. When the detection system works, the electrical signal generated by the axial magnetic field sensor (3) affected by the magnetic induction intensity at its spatial position is processed by a signal amplifier and a filter, and then the computer obtains a period of T detection signal S 0 through a data acquisition card, and this is used as a reference signal; Closely attach the imaging probe for detecting defects in the aviation metal component to the area to be measured of the aviation metal component and perform a scan with a step size of l 0. The scanned area is a rectangular scanned area with a length and width of m × l 0 and n × l 0, and obtain the scan signals S 1,1 , S 1,2 , S 1,3 , S 1,4 , …, S m,n-2 , S m,n-1 , S m,n . Subtract the above scan signals from the reference signal S 0 to obtain the corresponding differential signals D 1,1 , D 1,2 , D 1,3 , D 1,4 , …, D m,n-2 , D m,n-1 , D m,n ; Extract the part of each differential signal from 0 to 0.5 T to obtain the differential signals from 0 to 0.5 T Da 1,1 , Da 1,2 , Da 1,3 , Da 1,4 , …, Da m,n-2 , Da m,n-1 , Da m,n . Extract the part of each differential signal from 0.5 T ~ T to obtain the differential signals from 0.5 T ~ T Db 1,1 , Db 1,2 , Db 1,3 , Db 1,4 , …, Db m,n-2 , Db m,n-1 , Db m,n ; Extract each of the 0 to 0.5 T differential signals Da 1,1 , Da 1,2 , Da 1,3 , Da 1,4 , …, Da m,n-2 , Da m,n-1 , Da m,n peak values, obtaining Pa 1,1 , Pa 1,2 , Pa 1,3 , Pa 1,4 , …, Pa m,n-2 , Pa m,n-1 , Pa m,n , and further obtaining a size of m × n 0 to 0.5 T two-dimensional scanning feature matrix ka ; Extract each of the 0.5 T ~ T differential signals Db 1,1 , Db 1,2 , Db 1,3 , Db 1,4 , …, Db m,n-2 , Db m,n-1 , Db m,n peak values, obtaining Pb 1,1 , Pb 1,2 , Pb 1,3 , Pb 1,4 , …, Pb m,n-2 , Pb m,n-1 , Pb m,n , and further obtaining a size of m × n 0.5 of T ~ T two-dimensional scanning feature matrix kb ; 2) Defect imaging of aviation metal components, and the specific method is as follows: Calculate from 0 to 0.5 T Two-dimensional scanning feature matrix ka The gradient values of each element along the vertical direction are obtained respectively Pza 1,1 , Pza 1,2 , Pza 1,3 , Pza 1,4 ,…, Pza m,n-2 , Pza m,n-1 , Pza m,n , and extract its maximum value Pza m; Calculate from 0 to 0.5 T Two-dimensional scanning feature matrix ka The gradient values of each element along the horizontal direction are obtained respectively Pha 1,1 , Pha 1,2 , Pha 1,3 , Pha 1,4 ,…, Pha m,n-2 , Pha m,n-1 , Pha m,n , extract its maximum value Pha Extract the maximum element from the two-dimensional scanning feature matrix from 0 to 0.5 T Two-dimensional scanning feature matrix ka The maximum element Pa m; For the two-dimensional scanning feature matrix from 0 to 0.5 T Two-dimensional scanning feature matrix ka All elements are calculated and processed to obtain the two-dimensional scanning feature processed matrix from 0 to 0.5 T Two-dimensional scanning feature processed matrix kat , from 0 to 0.5 T Two-dimensional scanning feature processed matrix kat Any element kat i,j=(( Pza i,j / Pza m) 2 +( Pha i,j / Pha m) 2 ) 1 / 2 / (( Pza i,j / Pza m) 2 +( Pha i,j / Pha m) 2 +( Pa i,j / Pa m) 2 +1) 1 / 2 ； Calculate 0.5 T ~ T Two-dimensional scanning feature matrix kb The gradient values of each element along the vertical direction are obtained respectively Pzb 1,1 , Pzb 1,2 , Pzb 1,3 , Pzb 1,4 ,…, Pzb m,n-2 , Pzb m,n-1 , Pzb m,n ,and extract its maximum value Pzb m; Calculate 0.5 T ~ T Two-dimensional scanning feature matrix kb For each element, obtain the gradient value along the horizontal direction respectively to get Phb 1,1 , Phb 1,2 , Phb 1,3 , Phb 1,4 ,…, Phb m,n-2 , Phb m,n-1 , Phb m,n ,extract its maximum value Phb m; extract 0.5 T ~ T Two-dimensional scanning feature matrix kb The maximum element in Pb m; for 0.5 T ~ T Two-dimensional scanning feature matrix kb Perform calculation processing on all elements to obtain 0.5 T ~ T Two-dimensional scanning feature processed matrix kbt ,0.5 T ~ T Two-dimensional scanning feature processed matrix kbt Any element in kbt i,j = (( Pzb i,j / Pzb m) 2 +( Phb i,j / Phb m) 2 ) 1 / 2 / (( Pzb i,j / Pzb m) 2 +( Phb i,j / Phb m) 2 +( Pb i,j / Pb m) 2 +1) 1 / 2 ; Use the Canny algorithm to perform edge recognition on the image formed by the matrix after processing the two-dimensional scanning features from 0 to 0.5 T to obtain the edge recognition matrix from 0 to 0.5 kat ; in the edge recognition matrix from 0 to 0.5 T the elements with a median value of 1 represent the image edges. Assign the value of 1 to the elements located within the image edges to obtain the image matrix from 0 to 0.5 katc ; T edge recognition matrix katc ; the elements with a median value of 1 in the edge recognition matrix from 0 to 0.5 represent the image edges. Assign the value of 1 to the elements located within the image edges to obtain the image matrix from 0 to 0.5 T image matrix katd ; Use the Canny algorithm to perform edge recognition on the image formed by the matrix after processing the two-dimensional scanning features from 0.5 T ~ T to obtain the edge recognition matrix from 0.5 kbt ~ T ~ T ; for the edge recognition matrix from 0.5 kbtc ~ T ~ T , the elements with a median value of 1 represent the image edges. Assign a value of 1 to the elements located within the image edges to obtain the image matrix from 0.5 kbtc ~ T ~ T ; kbtd ; Calculate matrix 0 to 0.5 T Image katd The sum of all elements is katds , calculate 0.5 T to T Image matrix kbtd The sum of all elements is kbtds , if katds + kbtds ≥ 0.5π Φ 2 , then it is considered that the morphology of the defect in the detection area is 0.5 T to T Image matrix kbtd The grayscale image shown; If katds + kbtds <0.5π Φ 2 then it is considered that the morphology of the defect in the detection area is 0 to 0.5 T image matrix katd shown grayscale image.

2. The method for defect detection imaging of an aviation metal component according to claim 1, wherein: Outer disk type excitation coil (2) outer diameter Φ is twice the outer diameter of the inner disk type excitation coil (1), and the outer disk type excitation coil (2) and the inner disk type excitation coil (1) have the same height and the same number of coil turns. The balancing device (4) is annular and has the same height as the axial magnetic field sensor (3). φ ​

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