CN115856071A - Device and method for detecting damage of metal substrate under coating based on multi-frequency eddy current excitation and magnetic field detection - Google Patents

Abstract

The invention provides an under-coating metal substrate damage detection device and detection method based on multi-frequency eddy current excitation and magnetic field detection, including a multi-frequency eddy current excitation signal generator, an excitation coil, a magnetic field data collector, a linear array magnetic field detection sensor and data processing The module and display, the linear array magnetic field detection sensor is located in the excitation coil; the detection method includes selecting the frequency gear for detection, obtaining the magnetic field data at multiple excitation frequencies, and performing three-dimensional reconstruction on the magnetic field data maps scanned at all frequencies to obtain the A three-dimensional image of the site is measured and the damage shown in the image is analyzed. The invention can obtain damage data under multiple excitation frequencies through one scan, and can realize non-destructive detection and analysis of metal substrate cracks, corrosion and other damage without removing the organic coating or thin metal covering layer on the surface of the metal material. It has the advantage of high detection efficiency.

Description

Damage detection device for metal substrate under coating based on multi-frequency eddy current excitation and magnetic field detection setting and detection method

technical field

The invention belongs to the technical field of nondestructive testing, and in particular relates to a damage detection device and a detection method for an undercoated metal substrate based on multi-frequency eddy current excitation and magnetic field detection.

background technology

The use of alternating current can form eddy currents on the surface of metal materials. When there are cracks and corrosion damage on the metal surface, the eddy currents will change, and the magnetic field formed by the eddy currents will change. Using a magnetic field sensor to detect changes in the magnetic field formed by eddy currents can determine the damage to the surface and subsurface of metal materials. However, the existing eddy current excitation detection devices all use a single frequency for excitation, and the magnetic field data acquired each time is generated by a single frequency excitation, which not only has the problem of low damage detection efficiency, but also easily misses the damage of the workpiece. And when exploring the test parameters of different samples and different damages, it takes a long time to explore the process. In view of this, it is necessary to provide an eddy current magnetic field detection device and a detection method capable of improving damage detection efficiency and detection accuracy. More importantly, the existing eddy current excitation detection method cannot accurately and quickly determine the depth interval of the damage.

Contents of the invention

The purpose of the present invention is to provide a damage detection device and detection method for under-coated metal substrates based on multi-frequency eddy current excitation and magnetic field detection with high damage detection efficiency and high detection accuracy.

The technical scheme adopted in the present invention is as follows.

An under-coating metal substrate damage detection device based on multi-frequency eddy current excitation and magnetic field detection, including multi-frequency eddy current excitation signal generator, excitation coil, magnetic field data collector, linear array magnetic field detection sensor, data processing module and display, linear The array magnetic field detection sensor is fixedly connected to the excitation coil and located in the excitation coil; among them, the multi-frequency eddy current excitation signal generator is used to generate multi-frequency excitation signals and form a magnetic field at the measured part, and synchronously generate a frequency mark signal, and the mark signal Synchronously transmitted to the magnetic field data collector; the linear array magnetic field detection sensor is used to detect the magnetic field data under different excitation frequencies, and correspondingly record and extract the magnetic field data under different excitation frequencies, and transmit the magnetic field data to the magnetic field data collector; the magnetic field The data collector is used to acquire magnetic field data and frequency marker signals, match and store the magnetic field data and frequency marker signals, and feed them back to the data processing module; the data processing module is used to generate magnetic field data maps from the read magnetic field data and output them.

In the present invention, the multi-frequency excitation signal includes the first gear frequency sent in the first millisecond time period T1, the second gear frequency sent in the second millisecond time period T2 ... the Kth millisecond time period T _K The total time of all millisecond-level periods is controlled within one second for the K-th frequency, and the detection thickness interval corresponding to the first frequency is 0-h ₁ mm, and the detection thickness interval corresponding to the second frequency is 0-h ₂ mm, the detection thickness interval corresponding to the K-th gear frequency is 0-h _K mm, the position of 0mm represents the detection reference plane, the position of h1 mm represents the position where the depth of the detection reference plane is h _K mm, h ₁ <h ₂ < h _K .

Preferably, the linear array magnetic field detection sensor is a giant magnetoresistance sensor or a tunnel magnetoresistance sensor.

In the present invention, it also includes a position sensor installed on the excitation coil, the position sensor is used to obtain the position of the detection part in real time, and feeds back the position data to the magnetic field data collector, and the magnetic field data collector combines its position information with magnetic field data, frequency Mark the signal for matching.

In the present invention, when the metal substrate is aluminum alloy, the corresponding frequency is 1kHz-40kHz, and each frequency belongs to an arithmetic sequence; when the metal substrate is carbon steel, the corresponding frequency is 0.5kHz-30kHz, each The bin frequency belongs to the arithmetic sequence.

A detection method using the aforementioned metal substrate damage detection device, the steps comprising:

Step 1, placing the excitation coil and the linear array magnetic field detection sensor on the initial position of the surface of the metal substrate to be tested;

Step 2. Set the excitation signal frequency range of the multi-frequency eddy current excitation signal generator in combination with the material of the metal substrate to be tested;

Step 3, select the frequency range, including K frequency segments, move the excitation coil and the linear array magnetic field detection sensor along the detection path at a constant speed, and complete the thickness interval of 0-h ₁ mm, 0-h ₂ mm...0-h _k mm scan;

The magnetic field data corresponding to the thickness interval of multiple frequency ranges is acquired in one scan. The thickness interval corresponding to the first frequency range is 0-h ₁ mm, the thickness interval corresponding to the second frequency range is 0-h ₂ mm, and the thickness interval corresponding to the K-th frequency range The interval is 0-h _K mm;

In step 4, three-dimensional reconstruction is performed on the magnetic field data images scanned at all frequencies to obtain a three-dimensional image of the measured part, and the damage displayed in the three-dimensional image is analyzed.

Among them, the process of analyzing the damage in step 4 is as follows:

If there is no damage feature in the magnetic field data graph corresponding to the first frequency, it means that the first region with a thickness interval of 0-h ₁ mm has no damage;

If there is no damage feature in the magnetic field data graph corresponding to the second frequency, it means that there is no damage in the second area with a thickness interval of 0-h ₂ mm;

If there is no damage feature in the magnetic field data graph corresponding to the K-1 frequency, it means that the h K _-1 area with a thickness interval of 0-h _K-1 mm has no damage;

If there are damage features in the magnetic field data graph corresponding to the Kth gear frequency, it means that the damage exists in the thickness interval of

h _K-1 ~ h _K mm area.

Beneficial effects: adopting the solution of the present invention, damage data at multiple excitation frequencies can be acquired through one scan, and the crack and corrosion of the metal substrate can be realized without removing the organic coating or the thinner metal covering layer on the surface of the metal material. The non-destructive detection analysis of equal damage has the advantage of high detection efficiency; more importantly, the solution of the present invention can accurately and quickly determine the depth interval of the damage, and can identify the damage with a depth interval of 0.2-2mm.

Description of drawings

1 is a schematic diagram of an undercoating metal substrate damage detection device based on multi-frequency eddy current excitation and magnetic field detection in an embodiment;

Fig. 2 is a flow diagram of the metal substrate damage detection device based on multi-frequency eddy current excitation and magnetic field in the embodiment;

Fig. 3 is the magnetic field data graph that detection device obtains under different gear frequency in the embodiment;

FIG. 4 is a schematic diagram of a three-dimensional image of the measured part obtained after three-dimensional reconstruction.

Detailed ways

The present invention will be further described below in conjunction with the embodiments and accompanying drawings.

Example

An under-coating metal substrate damage detection device based on multi-frequency eddy current excitation and magnetic field detection, as shown in Figure 1 and Figure 2, includes a multi-frequency eddy current excitation signal generator, excitation coil 4, magnetic field data collector, linear array magnetic field The detection sensor 5 and the data processing module and the display 2, the linear array magnetic field detection sensor 5 are fixedly connected to the excitation coil 4 and are located in the excitation coil 4, and the multi-frequency eddy current excitation signal generator and the magnetic field data collector are installed in the same housing 1; , the multi-frequency eddy current excitation signal generator is used to generate multi-frequency excitation signals and form a magnetic field at the measured part, and synchronously generate a frequency mark signal, and synchronously transmit the mark signal to the magnetic field data collector; the linear array magnetic field detection sensor 5 is used It is used to detect the magnetic field data under different excitation frequencies, record and extract the magnetic field data under different excitation frequencies correspondingly, and transmit the magnetic field data to the magnetic field data collector; the magnetic field data The data is matched with the frequency marker signal, stored, and fed back to the data processing module; the data processing module is used to generate a magnetic field data map from the read magnetic field data and output it. Wherein, the linear array magnetic field detection sensor 5 adopts a giant magnetoresistive sensor. When in use, the linear array magnetic field detection sensor 5 and the excitation coil 4 are placed on the surface of the measured workpiece 3 as a whole, and during detection (scanning), the operator operates the linear array magnetic field detection sensor 5 and the excitation coil 4 as a whole along the detection path (Fig. 1) moving at a constant speed in the direction indicated by arrow 6, so as to detect the damage 7 (damage) on the metal substrate.

Among them, the multi-frequency eddy current excitation signal generator can continuously generate multiple levels of different frequencies within a second-level period, and a programmable signal generator can be used, and these required frequency levels can be set by those skilled in the art through programming. In this embodiment, the multi-frequency excitation signal generated by the multi-frequency eddy current excitation signal generator includes the first frequency (40kHz) issued in the first millisecond period T1 (0-100ms), and the second millisecond period T2 The second frequency (30kHz) issued within (100-200ms) ... the fourth frequency (10kHz) issued within the fourth millisecond period T ₄ (300-400ms), the total duration of all millisecond periods ( 400ms) within one second; the detection thickness interval corresponding to the first frequency is 0-h ₁ mm (h ₁ =0.4mm), and the detection thickness interval corresponding to the second frequency is 0-h ₂ mm (h ₂ =0.8 mm), the detection thickness interval corresponding to the fourth gear frequency is 0-h _K mm (h ₄ =1.6mm), the position of 0mm indicates the detection reference surface, and the position of h1 mm indicates that the depth of the detection reference surface is h _K mm. position, h ₁ <h ₂ <h _K .

In this embodiment, it also includes a position sensor installed on the excitation coil 4, the position sensor is used to obtain the position of the detection part in real time (the detection path is pre-marked with coordinate information), and the position data is fed back to the magnetic field data collector, the magnetic field data The collector matches its position information with magnetic field data and frequency marker signals.

In the present invention, the frequency of the multi-frequency eddy current excitation signal generator is adjustable, and each gear frequency belongs to an arithmetic sequence (0.5kHz, 1kHz, 1.5kHz, 1.5kHz...100kHz,), and the frequency range is 0.5kHz-100kHz.

A detection method using the metal substrate damage detection device in this embodiment, the steps include:

Step 1, as shown in Figure 1, the excitation coil 4 and the linear array magnetic field detection sensor 5 are placed on the initial position of the surface of the metal substrate 3 to be tested;

Step 2. Set the excitation signal frequency of the multi-frequency eddy current excitation signal generator in combination with the material of the metal substrate to be tested;

Step 3, select the frequency range (including K frequency segments, theoretically speaking, the more frequency segments, the smaller the thickness interval difference), move the excitation coil 4 and the linear array magnetic field detection sensor 5 at a constant speed along the detection path to complete the thickness The scanning interval is 0-h ₁ mm, 0-h ₂ mm...0-h _k mm; in Figure 3, the gray area indicates the shape of the damaged plane obtained by scanning, the X-axis of the two-dimensional coordinates indicates the length, and the Y-axis indicates the width , the curve represents the cross-sectional data curve of the damage magnetic field intensity;

Step 4: Perform three-dimensional reconstruction on the magnetic field data images scanned at all frequencies to obtain a three-dimensional image of the measured part (as shown in Figure 4), and analyze the damage displayed in the three-dimensional image. In this example, combined with the analysis of Figure 3, it can be seen that the magnetic field data graphs corresponding to the first to fourth frequencies all show damage characteristics, indicating that the area with a thickness interval of 0-h ₄ mm has damage.

In the actual application scheme, the process of analyzing the damage in step 4 is as follows:

If there is no damage feature in the magnetic field data graph corresponding to the first frequency, it means that the first region with a thickness interval of 0-h ₁ mm has no damage;

If there is no damage feature in the magnetic field data graph corresponding to the second frequency, it means that there is no damage in the second area with a thickness interval of 0-h ₂ mm;

If there is no damage feature in the magnetic field data graph corresponding to the K-1 frequency, it means that the h K _-1 area with a thickness interval of 0-h _K-1 mm has no damage;

If there are damage features in the magnetic field data graph corresponding to the Kth gear frequency, it means that the damage exists in the thickness interval of

h _K-1 ~ h _K mm area;

If there are damage features in the magnetic field data graph corresponding to the first frequency, it means that there is damage in the area with a thickness range of 0-h ₁ mm or below this area, and further analysis of the magnetic field data graph corresponding to the next frequency is required until finding The depth zone where the damage is located.

With this solution, damage data at multiple excitation frequencies can be obtained through one scan, and cracks in the metal substrate can be realized without removing the organic coating or thin metal covering layer (thickness 0-3mm) on the surface of the metal material. The non-destructive testing and analysis of damage such as corrosion and corrosion has the advantage of high detection efficiency; more importantly, the solution can accurately and quickly determine the depth range of the damage.

Claims (7)

1. Metal substrate damage detection device under coating based on multifrequency eddy current excitation and magnetic field are surveyed, its characterized in that: the linear array magnetic field detection sensor is fixedly connected with the exciting coil and positioned in the exciting coil; the multi-frequency eddy current excitation signal generator is used for generating a multi-frequency excitation signal, forming a magnetic field at a detected part, synchronously generating a frequency marking signal and synchronously transmitting the marking signal to the magnetic field data collector; the linear array magnetic field detection sensor is used for detecting magnetic field data under different excitation frequencies, correspondingly recording and extracting the magnetic field data under different excitation frequencies, and transmitting the magnetic field data to the magnetic field data acquisition unit; the magnetic field data acquisition unit is used for acquiring magnetic field data and frequency marking signals, matching and storing the magnetic field data and the frequency marking signals, and feeding back the magnetic field data and the frequency marking signals to the data processing module; and the data processing module is used for generating a magnetic field data graph from the read magnetic field data and outputting the magnetic field data graph.

2. The metal matrix damage detection device of claim 1, wherein: the multi-frequency excitation signal comprises a first gear frequency emitted in a first millisecond-level time period T1, a second gear frequency … emitted in a second millisecond-level time period T2 and a Kth millisecond-level time period T _K The frequency of the K gear is sent out, and the total duration of all millisecond-level time periods is controlled within one second; the detection thickness interval corresponding to the first gear frequency is 0-h ₁ mm, the detection thickness interval corresponding to the second gear frequency is 0-h ₂ mm, the detection thickness interval corresponding to the K-th gear frequency is 0-h _K mm, the position of 0mm represents the detection reference surface, the position of h1 mm represents the downward depth of the detection reference surface as h _K Position of mm, h ₁ ＜h ₂ ＜h _K 。

3. The metal matrix damage detection device of claim 2, wherein: the linear array magnetic field detection sensor is a giant magnetoresistance sensor or a tunnel magnetoresistance sensor.

4. The metal matrix damage detection device of claim 3, wherein: the magnetic field data acquisition device is used for acquiring the position of a detected part in real time and feeding back the position data to the magnetic field data acquisition unit, and the magnetic field data acquisition unit matches the position information with the magnetic field data and the frequency marking signals.

5. The metal matrix damage detection device of claim 4, wherein: when the metal matrix is aluminum alloy, the corresponding frequency is 1kHz-50kHz, and the frequencies of all gears are arranged in an equal order mode; when the metal matrix is carbon steel, the corresponding frequency is 0.5kHz-50kHz, and the frequencies of all the gears are arranged in an equal order mode.

6. A method of detecting damage to a metal substrate using the apparatus for detecting damage to a metal substrate according to claim 5, comprising the steps of:

step 1, placing an exciting coil and a linear array magnetic field detection sensor at the initial position of the surface of a metal matrix to be detected;

step 2, setting excitation signal frequency of the multi-frequency eddy current excitation signal generator by combining the material of the metal matrix to be detected;

and 3, selecting a frequency range comprising K frequency sections, moving the exciting coil and the linear array magnetic field detection sensor at a constant speed along a detection path, and finishing the thickness interval of 0-h ₁ mm、0-h ₂ mm……0-h _k Scanning mm;

and 4, performing three-dimensional reconstruction on the magnetic field data image obtained by scanning under all frequencies to obtain a three-dimensional image of the detected part, and analyzing the damage displayed in the three-dimensional image.

7. The method for detecting the damage of the metal substrate detection device according to claim 6, wherein the process of analyzing the damage in the step 4 is as follows:

if the magnetic field data graph corresponding to the first gear frequency does not show damage characteristics, the thickness interval is represented to be 0-h ₁ The mm first area is not damaged;

if the magnetic field data graph corresponding to the second gear frequency does not show damage characteristics, the thickness interval is represented to be 0-h ₂ The mm second area is not damaged;

if the magnetic field data graph corresponding to the K-1 gear frequency does not show damage characteristics, the thickness interval is represented as 0-h _K-1 H of mm _K-1 The area is not damaged;

if the magnetic field data graph corresponding to the K-th gear frequency shows the damage characteristic, the damage exists in the thickness interval h _K-1 ～h _K Area of mm.

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