CN115308297A - Defect signal quantization method and system based on circumferential excitation device - Google Patents

Abstract

The invention discloses a method and a system for quantifying a defect signal based on a circumferential excitation device, and relates to the field of nondestructive testing of pipelines. The method comprises the following steps: the magnetic leakage data of the circumferential excitation device are obtained through detection, the magnetic leakage data are preprocessed, signal characteristic quantities with quantized defects are selected from the preprocessed magnetic leakage data, and defect signal quantization is carried out on the magnetic leakage data according to the signal characteristic quantities. The defect signal quantization method has the advantages of strong detection capability on the axial cracks of the pipeline, simple data preprocessing process, less characteristic quantity required by quantization, easy implementation and high quantization accuracy.

Description

Defect signal quantization method and system based on circumferential excitation device

Technical Field

The invention relates to the field of nondestructive detection of pipelines, in particular to a method and a system for quantizing a defect signal based on a circumferential excitation device.

Background

Pipeline transportation is an important mode for large-scale petroleum and natural gas transmission, and a long oil and gas transmission pipeline has the defects that the pipe wall is easy to corrode, erode, crack and the like in the long-term operation process due to long transportation distance and complex transportation working conditions. The defects develop to a certain degree, the pipeline fails, medium leakage can be caused, even accidents such as explosion and the like which harm the economy, lives and properties of people at extreme can occur. In order to ensure production safety, professional detection personnel need to regularly perform online detection on the pipeline, find hidden troubles of pipeline defects in time, position the defects and perform repair treatment.

Magnetic leakage detection is a main way of detecting defects of pipelines, and utilizes an electromagnetic effect to detect the transmission characteristics of ferromagnetic materials in a magnetic loop. The basic principle is as follows: an excitation magnetic field generated by a permanent magnet or an electromagnet is utilized to locally magnetize the ferromagnetic pipeline to a near-saturation or saturated state through a closed magnetic loop formed by a steel brush, the pipeline and a yoke; if there is an air region such as a defect or crack on or near the surface of the pipeline, since the magnetic permeability of the pipeline is much greater than that of air, the magnetic induction lines will preferentially pass through the pipeline portion with higher magnetic permeability, so that a considerable portion of the magnetic induction lines will be forced to bypass the defect position, and compression will be formed on the magnetic induction lines. The magnetic induction line quantity that the continuation of pipeline can hold is limited, can repel each other between the magnetic induction line of homopolar moreover, has a certain quantity magnetic induction line will wear out from the defect position, and the entering air produces the magnetic leakage flux, and inside the pipeline will be got back to most magnetic induction line behind the defect, formation magnetic leakage field. The difference of the defect shape and the geometric dimension can cause the formed leakage magnetic field signal to change correspondingly.

The traditional pipeline magnetic flux leakage detection method usually adopts an axial excitation mode, and the axial excitation magnetic flux leakage mode cannot detect the defects of narrow cracks, welding seams, mechanical damage, corrosion pits and the like of axial guidance.

Disclosure of Invention

The invention aims to solve the technical problem of the prior art and provides a method and a system for quantizing a defect signal based on a circumferential excitation device.

The technical scheme for solving the technical problems is as follows:

a method for quantizing a defect signal based on a circumferential excitation device comprises the following steps:

magnetic flux leakage data of the circumferential excitation device are obtained through detection;

preprocessing the magnetic leakage data;

selecting a signal characteristic quantity with a quantization defect from the preprocessed magnetic flux leakage data;

and performing defect signal quantization on the magnetic leakage data according to the signal characteristic quantity.

The invention has the beneficial effects that: the defect signal quantification method is suitable for detecting a pipeline made of ferromagnetic materials and a magnetizer with a magnetic pole separation ring-shaped structure, and the yoke adopts a ring-shaped structure, so that the magnetic resistance loss caused by an air gap can be effectively reduced, and a sensor is conveniently arranged and installed on the outer wall of the ring-shaped yoke. The excitation device has strong detection capability on the axial cracks of the pipeline, has a simple integral structure, and can realize diameter change so as to facilitate the detection device to smoothly pass through the diameter change area of the pipeline. The method for quantizing the defect signals is simple in data preprocessing process, small in feature quantity required by quantization, easy to implement and high in quantization accuracy.

Further, the preprocessing the magnetic leakage data specifically includes:

and preprocessing the magnetic leakage data by a polynomial least square fitting method and an interpolation method.

The beneficial effect of adopting the further scheme is that: according to the scheme, cubic spline interpolation smoothing processing is performed on the fitted signal curve through least square fitting and interpolation, and a smooth signal capable of accurately reflecting the size and the change rule of the leakage magnetic field of the defect is obtained.

Further, the performing the defect signal quantization on the magnetic leakage data according to the signal feature quantity specifically includes:

and quantizing the defect length, width and depth of the magnetic leakage data according to the signal characteristic quantity.

Further, the signal feature quantity includes: a radial component peak-to-peak value, a radial component peak-to-peak spacing, a circumferential component peak-to-valley value, and a circumferential component differential signal peak-to-peak spacing.

Further, the quantizing the magnetic flux leakage data according to the signal characteristic quantity includes:

according to the peak value of the radial component and the peak value of the circumferential component, carrying out defect depth quantification;

quantifying the defect length according to the running speed of the detection device, the sampling frequency of the detection device and the number of sampling points covered by the magnetic leakage signal change area;

and quantifying the defect width according to the peak-to-peak distance of the radial component and the peak-to-peak distance of the circumferential component differential signal.

The beneficial effect of adopting the further scheme is that: according to the scheme, the defect signal quantization method which is suitable for the defect depth, the defect signal quantization method which is suitable for the defect signal quantization method is simple in data preprocessing process, small in feature quantity required by quantization, easy to implement and high in quantization accuracy.

Another technical solution of the present invention for solving the above technical problems is as follows:

a system for quantizing a defect signal based on a circumferential excitation device comprises: the device comprises a detection module, a preprocessing module, a selection module and a quantization module;

the detection module is used for obtaining magnetic flux leakage data of the circumferential excitation device through detection;

the preprocessing module is used for preprocessing the magnetic leakage data

The selection module is used for selecting signal characteristic quantity with quantitative defects from the preprocessed magnetic leakage data;

and the quantization module is used for performing defect signal quantization on the magnetic leakage data according to the signal characteristic quantity.

The invention has the beneficial effects that: the defect signal quantification method is suitable for detecting a pipeline made of ferromagnetic materials and a magnetizer with a magnetic pole separation ring-shaped structure, and the yoke adopts a ring-shaped structure, so that the magnetic resistance loss caused by an air gap can be effectively reduced, and a sensor is conveniently arranged and installed on the outer wall of the ring-shaped yoke. The excitation device has strong detection capability on the axial cracks of the pipeline, has a simple integral structure, and can realize diameter change so as to facilitate the detection device to smoothly pass through the diameter change area of the pipeline. The adaptive defect signal quantization method has the advantages of simple data preprocessing process, less characteristic quantity required by quantization, easy implementation and high quantization accuracy.

Further, the preprocessing module is specifically configured to preprocess the magnetic flux leakage data through a polynomial least squares fitting method and an interpolation method.

The beneficial effect of adopting the above further scheme is: according to the scheme, cubic spline interpolation smoothing processing is performed on the fitted signal curve through least square fitting and interpolation, and a smooth signal capable of accurately reflecting the size and the change rule of the defect leakage magnetic field is obtained.

Further, the quantization module is specifically configured to quantize the defect length, the width, and the depth of the leakage magnetic data according to the signal feature quantity.

Further, the signal feature quantity includes: a radial component peak-to-peak value, a radial component peak-to-peak spacing, a circumferential component peak-to-valley value, and a circumferential component differential signal peak-to-peak spacing.

Further, the quantization module is specifically configured to perform defect depth quantization according to a radial component peak-to-peak value and a circumferential component peak-to-valley value;

quantifying the defect length according to the running speed of the detection device, the sampling frequency of the detection device and the number of sampling points covered by the magnetic leakage signal change area;

and quantifying the defect width according to the peak-to-peak distance of the radial component and the peak-to-peak distance of the circumferential component differential signal.

The beneficial effect of adopting the above further scheme is: the proposal adopts a defect signal quantization method which is suitable for the depth, the length and the width of the defect, the data preprocessing process is simple, the characteristic quantity required by quantification is small, the implementation is easy, and the quantification accuracy is high.

Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Drawings

Fig. 1 is a schematic flow chart of a method for quantizing a defect signal based on a circumferential excitation device according to an embodiment of the present invention;

fig. 2 is a block diagram of a system for quantizing a defect signal based on a circumferential excitation device according to an embodiment of the present invention;

fig. 3 is a schematic diagram of a set of leakage magnetic signal characteristic quantities according to another embodiment of the present invention;

FIG. 4 is a graph of a defect signal fit provided by other embodiments of the present invention;

FIG. 5 is a graph illustrating interpolation smoothing of defect signals according to another embodiment of the present invention;

FIG. 6 is a set of graphs of defect signatures versus leakage flux signal signatures according to other embodiments of the present invention;

fig. 7 is a pipeline circumferential excitation device according to another embodiment of the present invention.

Detailed Description

The principles and features of the present invention will be described with reference to the following drawings, which are illustrative only and are not intended to limit the scope of the invention.

As shown in fig. 1, a method for quantizing a defect signal based on a circumferential excitation device according to an embodiment of the present invention includes:

the circumferential excitation magnetic leakage detection method has potential advantages for detecting and quantitatively evaluating the axial guide defect, the circumferential excitation magnetic leakage detection method realizes detection by depending on a magnetizing field distributed around a pipeline (circumferentially), the axial extension defect can obviously change the magnetic field distribution, and the magnetic leakage field is more easily detected.

In the related circumferential excitation device, for example, the yoke adopts a cross structure, although the structural design is simple, the distance between the pipe wall and the yoke is large, a large back bottom leakage magnetic field exists in a non-defective area, the acquisition and resolution of a defect leakage magnetic signal are influenced, and the cross structure is inconvenient for arranging and installing sensors; for example, the yoke adopts a ring structure, the structure can effectively reduce the magnetic resistance loss caused by an air gap, further improve the magnetization intensity, and also is beneficial to arranging and installing a sensor on the outer wall of the ring yoke, but the diameter cannot be changed, so that the pipeline passing capacity of the excitation device is limited. In addition, the leakage magnetic field distribution formed at the duct defect is different for different circumferential exciting devices, and it is necessary to propose a defect signal quantization method suitable for the structure.

The quantization of the defect signal relates to the preprocessing of the detection data, in the detected leakage magnetic field signal, due to the characteristics of each path of sensor, the installation error of the probe and the inconsistency of the hardware measurement amplifying circuit, the leakage magnetic signals acquired by each channel sensor to the same defect in the finally obtained leakage magnetic signal are different and have deviation, and data errors or singular points can be caused by some accidental factors, so that the measurement standard is inconsistent, and an effective data preprocessing means is required before the quantization of the defect signal.

S1, magnetic flux leakage data of a circumferential excitation device are obtained through detection; wherein the magnetic leakage data comprises data of a pipeline defect signal.

S2, preprocessing the magnetic flux leakage data;

in a certain embodiment, the pre-processing process may include: and performing polynomial least square fitting processing on the measured data curve to reduce accidental errors in the detection process and play a role in eliminating singular points. And (4) performing cubic spline interpolation smoothing processing on the fitted data curve, and taking the boundary condition as a natural boundary condition. The corrected signals of each channel can accurately reflect the magnitude and the change rule of the leakage magnetic field of the defect. Each channel signal may include: the magnetic field detects the signal acquired by the sensor channel. The magnetic field detection sensor can acquire a radial component of a magnetic leakage signal, an axial component of the magnetic leakage signal and a circumferential component of the magnetic leakage signal.

Wherein the boundary conditions are as follows: the natural boundary condition of cubic spline interpolation refers to a boundary condition that the second derivative of the endpoint of the interval is O. Assuming that n +1 sampling points exist on the intervals [ a, b ], the intervals [ a, b ] are divided into n intervals, and the interpolation function is a cubic equation on each subsection interval; each subinterval has 4 unknowns, and there are n total intervals, so a total of 4n unknowns needs to be solved, and at least 4n constraint conditions are needed. Except for two end points, the first derivatives of all n-1 internal points are continuous, namely the values of the first derivatives of the left cubic function and the right cubic function at all points are equal, and n-1 equations are shared; except for two end points, the second derivatives of all n-1 internal points are continuous, namely the values of the second derivatives of the left cubic function and the right cubic function at all points are equal, and n-1 equations are shared; except for two end points, all n-1 internal points satisfy that each point is continuous, namely the values of the left cubic function and the right cubic function at each point are equal, and n-1 equations are total; the two endpoints respectively satisfy the first cubic function equation and the last cubic function equation, and the total number of the two endpoints is 2; natural boundary: the second derivative at the end point is zero, and there are 2 equations.

The above satisfies 4n constraint conditions, and 4n unknowns can be solved.

S3, selecting signal characteristic quantity with quantization defects from the preprocessed magnetic flux leakage data;

and S4, performing defect signal quantization on the magnetic leakage data according to the signal characteristic quantity.

It should be noted that, in a certain embodiment, S3 specifically includes:

acquiring the characteristic quantity of the quantized defect from the preprocessed signal curve: radial component B _r Peak to peak value B _rp-p 、B _r Peak-to-peak spacing S _rp-p Component B in the circumferential direction _θ Peak to valley value B _θp-p And B _θ Differential signal peak-to-peak spacing DS _θp-p 。

Quantification of defect length, width, depth: the pipeline circumferential excitation magnetic leakage detection method can detect axially distributed defects (narrow cracks), magnetic leakage signal modes of the defects with the same shape but different depths are basically consistent, and the differences mainly include that the amplitude of the magnetic leakage signal is different, the deeper the defect is, the stronger the magnetic leakage signal is, the radial peak-to-peak value and the circumferential peak-to-valley value of the magnetic leakage signal are in a near-linear relation with the depth of the defect, and the radial peak-to-peak value and the circumferential peak-to-valley value of the magnetic leakage signal can be used as signal characteristics for evaluating the depth of the defect; the width of the defect and the radial peak-to-peak distance of the magnetic leakage signal form a linear relation, and the circumferential width of the defect can be judged according to the important information; the magnetic leakage signal modes of the defects with different lengths are basically consistent, the main difference is that the magnetic leakage signal expands along the axial direction along with the increase of the length of the defect, and the axial length of the defect can be estimated according to the number of sampling points and the distance of the detected magnetic leakage signal.

Quantification of defect length: the defect length is calculated by the length of time (mileage) that the leakage magnetic signal change region covers a single sensor. Assuming that the operation speed of the detection device is v (m/s), the sampling frequency is f (kHz), and the number of sampling points covered by the leakage magnetic signal variation region is n, the defect length l (mm) can be estimated by the following formula:

quantification of defect width: radial component B of leakage signal _r Peak to peak spacing S _rp-p And a circumferential component B _θ Differential signal peak-to-peak spacing DS _θp-p Quantification of defect width can be achieved. And performing regression analysis on the magnetic leakage signal characteristic quantity and the defect width, and determining undetermined coefficients through the regression analysis to obtain a regression formula. The regression model adopts a binary regression model, and the quantization formula is as follows: w = beta ₀ +β ₁ S _rp-p +β ₂ DS _θp-p Wherein w is the defect width, S _rp-p Peak-to-peak value, DS, of the radial leakage signal _θp-p Is the peak-to-peak distance, beta, of the differentiated circumferential leakage magnetic signal ₀ 、β ₁ 、β ₂ Is the undetermined coefficient;

and (3) quantification of defect depth: radial component B of leakage signal _r Peak to peak value B _rp-p And a circumferential component B _θ Peak to valley value B _θp-p The defect depth can be described. And performing regression analysis on the characteristic quantity of the magnetic flux leakage signal and the defect depth, and determining undetermined coefficients through the regression analysis to obtain a regression formula. The regression model adopts a binary regression model, and the quantization formula is as follows: d = beta ₃ +β ₄ B _rp-p +β ₅ B _θp-p Wherein d is the depth of the defect, B _rp-p Peak-to-peak value of radial magnetic flux leakage signal, B _θp-p Is the peak-to-valley value of the circumferential magnetic flux leakage signal, beta ₃ 、β ₄ 、β ₅ Is the undetermined coefficient;

the defect signal quantification method is suitable for detecting a pipeline made of ferromagnetic materials and a magnetizer with a magnetic pole separation ring-shaped structure, and the yoke adopts a ring-shaped structure, so that the magnetic resistance loss caused by an air gap can be effectively reduced, and a sensor is conveniently arranged and installed on the outer wall of the ring-shaped yoke. The device has strong detection capability on the axial cracks of the pipeline, has a simple integral structure, can realize diameter change, and is favorable for the detection device to smoothly pass through a pipeline diameter change area. The method for quantizing the defect signals is simple in data preprocessing process, small in feature quantity required by quantization, easy to implement and high in quantization accuracy.

Optionally, in any embodiment above, the preprocessing the magnetic leakage data specifically includes:

and preprocessing the magnetic leakage data by a polynomial least square fitting method and an interpolation method.

In one embodiment, as shown in fig. 4, a defect signal is fitted to a graph, where a broken line formed by connecting solid points in the graph is a measurement signal, and the detection data is subjected to polynomial least square fitting to obtain a fitted signal formed by connecting hollow points.

In another embodiment, as shown in fig. 5, the defect signal is interpolated to smooth the graph, and the broken line in the graph is the fitting signal after the polynomial least square fitting process. Cubic spline interpolation smoothing processing is carried out on the fitted signal curve to obtain a smooth signal capable of accurately reflecting the size and the change rule of the leakage magnetic field of the defect

According to the scheme, cubic spline interpolation smoothing processing is performed on the fitted signal curve through least square fitting and interpolation, and a smooth signal capable of accurately reflecting the size and the change rule of the defect leakage magnetic field is obtained.

Optionally, in any embodiment above, the performing the defect signal quantization on the leakage magnetic data according to the signal feature quantity specifically includes:

and quantizing the defect length, width and depth of the magnetic leakage data according to the signal characteristic quantity.

In an embodiment, as shown in fig. 3, a group of leakage magnetic signal characteristic quantities is illustrated. The circumferential excitation magnetization field is vertical to the axial direction of the pipeline, and the axial component signal of the leakage magnetic field is weak and difficult to measure, so that the radial component and the circumferential component of the defect leakage magnetic field are measured. Radial component B of leakage signal _r Because the polarities of two sides of the defect are opposite, the leakage magnetic fields of the two sides have opposite signs, the maximum value is near the edge of the defect, and the leakage magnetic fields have a positive part and a negative partPeak value, and is symmetrical about the defect center; component in the circumferential direction B _θ Left-right symmetry, the component rapidly decreases from the defect center to the defect edge, having a positive peak and two valleys, reaching a maximum at the defect center. Differential pattern of circumferential component, analogous to radial component B _r The pattern has a maximum value near the edge of the defect, has a positive peak value and a negative peak value, and is symmetrical about the center of the defect. The signal characteristic quantities are: radial component B _r Peak to peak value B _rp-p 、B _r Peak to peak spacing S _rp-p Component B in the circumferential direction _θ Peak to valley value B _θp-p And B _θ Differential signal peak-to-peak spacing DS _θp-p 。

Optionally, in any embodiment above, the signal feature quantity includes: a radial component peak-to-peak value, a radial component peak-to-peak spacing, a circumferential component peak-to-valley value, and a circumferential component differential signal peak-to-peak spacing.

Optionally, in any embodiment above, the quantizing the leakage flux data according to the signal feature quantity specifically includes:

according to the peak value of the radial component and the peak value of the circumferential component, carrying out defect depth quantification;

quantifying the defect length according to the running speed of the detection device, the sampling frequency of the detection device and the number of sampling points covered by the magnetic leakage signal change area;

and quantifying the defect width according to the peak-to-peak distance of the radial component and the peak-to-peak distance of the circumferential component differential signal.

In an embodiment, as shown in fig. 6, a set of graphs relating defect characteristics to leakage magnetic signal characteristic quantities has a relatively obvious linear relationship with signal characteristics.

Quantification of defect length: the defect length is calculated by the length of time (mileage) that the leakage magnetic signal change region covers a single sensor. Assuming that the operation speed of the detection device is v (m/s), the sampling frequency is f (kHz), and the number of sampling points covered by the leakage magnetic signal variation region is n, the defect length l (mm) can be estimated by the following formula:

in this embodiment, the sampling frequency of the detector is 1kHz, the running speed of the detection device when passing through the defect is 1m/s, and the obtained quantization formula of the defect length is: l = n.

Quantification of defect width: radial component B of leakage signal _r Peak-to-peak spacing S _rp-p And a circumferential component B _θ Differential signal peak-to-peak spacing DS _θp-p For quantifying the defect width. And performing regression analysis on the characteristic quantity and the defect width of the magnetic leakage signal, wherein the regression model is as follows: w = beta ₀ +β ₁ S _rp-p +β ₂ DS _θp-p Wherein w is the defect width, S _rp-p Peak-to-peak value, DS, of the radial leakage signal _θp-p Is the peak-to-peak distance, beta, of the differentiated circumferential leakage magnetic signal ₀ 、β ₁ 、β ₂ Is a undetermined coefficient; beta solved by this example ₀ ＝-0.7478，β ₁ ＝0.5149，β ₂ =0.591, the resulting defect width quantization formula is:

w＝-0.7478+0.5149S _rp-p +0.591DS _θp-p 。

and (3) quantification of defect depth: radial component B of leakage signal _r Peak to peak value B _rp-p And a circumferential component B _θ Peak to valley value B _θp-p For quantifying the defect depth. And carrying out regression analysis on the characteristic quantity and the defect depth of the magnetic leakage signal, wherein the regression model is as follows: d = beta ₃ +β ₄ B _rp-p +β ₅ B _θp-p Wherein d is the depth of the defect, B _rp-p Peak-to-peak value of radial magnetic flux leakage signal, B _θp-p Is the peak-to-valley value of the circumferential magnetic flux leakage signal, beta ₃ 、β ₄ 、β ₅ Is a undetermined coefficient; beta solved by this example ₃ ＝0.1041，β ₄ ＝-6.7696，β ₅ =13.3149, the resulting defect depth quantization formula is:

d＝0.1041-6.7696B _rp-p +13.3149B _θp-p 。

according to the scheme, the defect signal quantization method which is suitable for the defect depth, the defect signal quantization method which is suitable for the defect signal quantization method is simple in data preprocessing process, small in feature quantity required by quantization, easy to implement and high in quantization accuracy.

In one embodiment, a method for quantizing a defect signal suitable for a circumferential excitation device includes S11, performing defect signal post-processing; s12, quantifying the defect parameters.

The step S11 specifically includes: performing polynomial least square fitting processing on the detection data to reduce accidental errors in the detection process and eliminate singular points; and performing cubic spline interpolation smoothing processing on the fitted data curve.

The step S12 specifically includes: and selecting the characteristic quantity of the magnetic leakage signal, and resolving undetermined parameters of the defect quantization model to obtain a determined quantization formula.

The length, the width and the depth of the defect are used for describing the shape of the defect (the length: the projection size of the defect in the axial direction, the width: the projection size of the defect in the circumferential direction and the depth: the projection size of the defect in the radial direction), and the quantitative model of the defect refers to a quantitative formula for calculating the length, the width and the depth of the defect.

The defect width and the defect depth can be expressed by the characteristic quantity of a leakage magnetic signal; the width can be expressed as the independent variable S _rp-p 、DS _θp-p A binary linear function of (a); depth can be expressed as an argument B _rp-p 、B _θp-p The undetermined parameters (also called undetermined coefficients) are solved by binary linear regression.

The defect shape parameters do not define the characteristics of the leakage magnetic signal, but affect the characteristics of the leakage magnetic signal (the peak-to-peak value of the radial component of the leakage magnetic signal, the distance between the peak and the peak after the differentiation of the circumferential component of the leakage magnetic signal, the peak-to-peak value of the radial component of the leakage magnetic signal, and the peak-to-valley value of the circumferential component of the leakage magnetic signal).

The undetermined parameter comprises beta in a defect width quantization formula ₀ 、β ₁ 、β ₂ Undetermined coefficient; (broadness quantization formula:

w＝β ₀ +β ₁ S _rp-p +β ₂ DS _θp-p )，

and beta in the defect width measurement formula ₃ 、β ₄ 、β ₅ Undetermined coefficient; the broadness quantization formula:

d＝β ₃ +β ₄ B _rp-p +β ₅ B _θp-p ，

the defect appearance parameters directly influence the characteristics of the magnetic leakage signals, the defects can be identified and evaluated by the characteristics of the magnetic leakage signals, and the characteristic quantity of the magnetic leakage signals is defined according to the characteristics of the magnetic leakage signals. The method for quantizing the defect signal of the circumferential excitation device adopts the following signal characteristic quantities: radial component B _r Peak to peak value B _rp-p 、B _r Peak-to-peak spacing S _rp-p Component B in the circumferential direction _θ Peak to valley value B _θp-p And B _θ Differential signal peak-to-peak spacing DS _θp-p . Wherein the radial component B _r The difference between the maximum value and the minimum value of (A) is called B _r Peak to peak value B _rp-p The circumferential distance between the maximum and minimum is called B _r Peak-to-peak spacing S _rp-p (ii) a Component in the circumferential direction B _θ The difference between the peak value and the valley value of the wave is B _θ Peak to valley value B _θp-p Component in the circumferential direction B _θ The circumferential distance between the maximum and minimum of the differentiated signal is the circumferential component B _θ Differential signal peak-to-peak spacing DS _θp-p . Wherein, the magnetic leakage signal is a function of defect shape parameters (length, width and depth) which influence the characteristic quantity of the magnetic leakage signal,

the characteristic quantities cannot be characterized by the shape parameters (length, width, depth), while the shape parameters (length, width, depth) can be characterized by formulas containing characteristic quantities.

In one embodiment, as shown in fig. 7, the pipeline circumferential excitation device comprises a permanent magnet, an arc yoke and a steel brush. The magnetic flux leakage detection device is characterized in that the permanent magnet and the yoke iron are divided into 4 groups of symmetrical structures, independent magnetic circuits are respectively formed with the pipe wall and the steel brush, and four independent magnetic flux leakage detection working areas are formed near the inner wall of the pipeline. The circumferential excitation devices can be used in pairs, are arranged in the axial direction in a front-back mode, and are arranged in a circumferential staggered mode.

In one embodiment, a pipeline circumferential excitation device specifically comprises a pipeline to be detected and a magnetizer. The magnetizer comprises a magnetic field source and a magnetic loop, the permanent magnet 3 is used as the magnetic field source, and the permanent magnet, the pipeline 1 to be detected, the steel brush 2 and the annular yoke iron 4 form the magnetic loop. The annular yoke iron 4 is connected with the permanent magnet 3, the permanent magnet 3 is connected with the steel brush 2, and the steel brush 2 is in contact with the inner wall of the pipeline 1 to be detected to form a circumferential magnetic loop. The permanent magnet 3 and the annular yoke iron 4 are divided into 4 groups of symmetrical structures, and 4 independent magnetic flux leakage detection working areas are formed near the inner wall of the pipeline 1. Among the permanent magnets, the permanent magnets 3.1 and 3.3 are permanent magnets of which S poles are connected with the steel brush 2; among the permanent magnets, the permanent magnets 3.2 and 3.4 are permanent magnets of which the N poles are connected with the steel brush 2. The pipeline circumference excitation device can arrange and install the sensor on the outer wall of ring yoke 4, because the separate structure of magnetic pole, the magnetizer can realize suitable reducing, does benefit to detection device and smoothly passes through areas such as pipeline reducing region elbow.

In one embodiment, as shown in fig. 2, a system for quantizing a defect signal based on a circumferential excitation device includes: the device comprises a detection module 1101, a preprocessing module 1102, a selection module 1103 and a quantization module 1104;

the detection module 11O1 is configured to obtain magnetic flux leakage data of the circumferential excitation device through detection;

the preprocessing module 1102 is configured to preprocess the magnetic leakage data

The selecting module 1103 is configured to select a signal feature quantity with a quantization defect from the preprocessed magnetic flux leakage data;

the quantization module 1104 is configured to perform defect signal quantization on the leakage magnetic data according to the signal feature quantity.

The defect signal quantization method is suitable for detecting a pipeline made of ferromagnetic materials and a magnetizer with a magnetic pole separation ring structure, the yoke adopts a ring structure, the magnetic resistance loss caused by air gaps can be effectively reduced, and a sensor is conveniently arranged and installed on the outer wall of the ring yoke. The excitation device has strong detection capability on the axial cracks of the pipeline, has a simple integral structure, and can realize diameter change so as to facilitate the detection device to smoothly pass through the diameter change area of the pipeline. The adaptive defect signal quantization method has the advantages of simple data preprocessing process, less characteristic quantity required by quantization, easy implementation and high quantization accuracy.

Optionally, in any embodiment above, the preprocessing module 1102 is specifically configured to preprocess the leakage magnetic data through a polynomial least squares fitting method and an interpolation method.

According to the scheme, cubic spline interpolation smoothing processing is performed on the fitted signal curve through least square fitting and interpolation, and a smooth signal capable of accurately reflecting the size and the change rule of the defect leakage magnetic field is obtained.

Optionally, in any embodiment described above, the quantization module 1104 is specifically configured to quantize the defect length, width, and depth of the leakage magnetic data according to the signal feature quantity.

Optionally, in any embodiment above, the signal feature quantity includes: a radial component peak-to-peak value, a radial component peak-to-peak spacing, a circumferential component peak-to-valley value, and a circumferential component differential signal peak-to-peak spacing.

Optionally, in any of the above embodiments, the quantization module 1104 is specifically configured to perform defect depth quantization according to a radial component peak value and a circumferential component peak-to-peak value;

quantifying the defect length according to the running speed of the detection device, the sampling frequency of the detection device and the number of sampling points covered by the magnetic leakage signal change area;

and quantifying the defect width according to the peak-to-peak distance of the radial component and the peak-to-peak distance of the circumferential component differential signal.

According to the scheme, the defect signal quantization method which is suitable for the defect depth, the defect signal quantization method which is suitable for the defect signal quantization method is simple in data preprocessing process, small in feature quantity required by quantization, easy to implement and high in quantization accuracy.

It is understood that some or all of the alternative embodiments described above may be included in some embodiments.

It should be noted that the above embodiments are product embodiments corresponding to the previous method embodiments, and for the description of each optional implementation in the product embodiments, reference may be made to corresponding descriptions in the above method embodiments, and details are not described here again.

The reader should understand that in the description of this specification, reference to the description of the terms "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described method embodiments are merely illustrative, and for example, the division of steps into only one type of logical functional division may be implemented in practice in other ways, for example, multiple steps may be combined or integrated into another step, or some features may be omitted, or not implemented.

The above method, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention essentially or partially contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-only memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.

While the invention has been described with reference to specific embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (10)

1. A method for quantizing a defect signal based on a circumferential excitation device is characterized by comprising the following steps:

magnetic flux leakage data of the circumferential excitation device are obtained through detection;

preprocessing the magnetic leakage data;

selecting a signal characteristic quantity with a quantization defect from the preprocessed magnetic flux leakage data;

and performing defect signal quantization on the magnetic leakage data according to the signal characteristic quantity.

2. The method for quantizing the defect signal based on the circumferential excitation device according to claim 1, wherein the preprocessing of the leakage magnetic data specifically comprises:

and preprocessing the magnetic flux leakage data by a polynomial least square fitting method and an interpolation method.

3. The method for quantizing the defect signal based on the circumferential excitation device according to claim 1, wherein the quantizing the leakage magnetic data according to the signal feature quantity includes:

and quantizing the defect length, width and depth of the magnetic leakage data according to the signal characteristic quantity.

4. The method for quantizing the defect signal based on the circumferential excitation device according to claim 3, wherein the signal characteristic quantity comprises: a radial component peak-to-peak value, a radial component peak-to-peak spacing, a circumferential component peak-to-valley value, and a circumferential component differential signal peak-to-peak spacing.

5. The method for quantizing the defect signal based on the circumferential excitation device according to claim 4, wherein the quantizing the leakage magnetic data according to the signal characteristic quantity includes:

according to the peak value of the radial component and the peak value of the circumferential component, carrying out defect depth quantification;

quantifying the defect length according to the running speed of the detection device, the sampling frequency of the detection device and the number of sampling points covered by the magnetic leakage signal change area;

and quantifying the defect width according to the peak-to-peak distance of the radial component and the peak-to-peak distance of the circumferential component differential signal.

6. A system for quantizing a defect signal based on a circumferential excitation device is characterized by comprising: the device comprises a detection module, a preprocessing module, a selection module and a quantization module;

the detection module is used for obtaining magnetic flux leakage data of the circumferential excitation device through detection;

the preprocessing module is used for preprocessing the magnetic leakage data

The selection module is used for selecting signal characteristic quantity with quantitative defects from the preprocessed magnetic leakage data;

and the quantization module is used for performing defect signal quantization on the magnetic leakage data according to the signal characteristic quantity.

7. The system of claim 6, wherein the preprocessing module is specifically configured to preprocess the leakage magnetic data through a polynomial least squares fitting method and an interpolation method.

8. The system of claim 6, wherein the quantization module is specifically configured to quantize the leakage magnetic data according to the signal feature quantity, the defect length, the width, and the depth.

9. The system of claim 8, wherein the signal characteristic quantity comprises: a radial component peak-to-peak value, a radial component peak-to-peak spacing, a circumferential component peak-to-valley value, and a circumferential component differential signal peak-to-peak spacing.

10. The system of claim 9, wherein the quantization module is specifically configured to perform defect depth quantization according to a radial component peak-to-peak value and a circumferential component peak-to-valley value;

quantifying the defect length according to the running speed of the detection device, the sampling frequency of the detection device and the number of sampling points covered by the magnetic leakage signal change area;

and quantifying the defect width according to the peak-to-peak distance of the radial component and the peak-to-peak distance of the circumferential component differential signal.

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