CN111256574B - Method and system for measuring thickness of metal pipeline - Google Patents
Method and system for measuring thickness of metal pipeline Download PDFInfo
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- CN111256574B CN111256574B CN202010216448.2A CN202010216448A CN111256574B CN 111256574 B CN111256574 B CN 111256574B CN 202010216448 A CN202010216448 A CN 202010216448A CN 111256574 B CN111256574 B CN 111256574B
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Abstract
The invention relates to a method and a system for measuring the thickness of a metal pipeline. The metal pipeline thickness measuring method comprises the following steps: acquiring an impedance-frequency curve group corresponding to the thickness of each set pipeline; determining the rotation intersection point of each set pipeline thickness according to all impedance-frequency curve groups; determining a cross point curve from the rotational cross points of all the set pipe thicknesses; determining a fitting equation of the thickness of the pipeline and the frequency value of the excitation signal according to the cross point curve; and determining the thickness of the metal pipeline to be measured according to the fitting equation. The invention realizes the safe, high-efficiency, low-cost and high-precision measurement of the thickness of the pipeline by utilizing the signal rotation cross point.
Description
Technical Field
The invention relates to the field of pipeline thickness measurement, in particular to a method and a system for measuring the thickness of a metal pipeline.
Background
Common nondestructive thickness measurement methods include a ray method, an ultrasonic method, an eddy current detection method and the like. The ray method has a large potential safety hazard in the detection process, and if the protection is not proper, the body of a detector is easily damaged; ultrasonic detection requires a large amount of coupling agent, and the detection precision is relatively low; in the in-service detection of the pipeline, the detection coil is usually operated manually, and the coil may be inclined arbitrarily. Because the sensitivity of eddy current detection is very high, the inclination of the coil can seriously affect the result of the eddy current detection of the pipeline, and the detection precision is reduced. With the arrival of the 4.0 era of industry, the dependence degree of the industrial production of informationized big data on high-precision data is higher and higher, and the requirement of the industry on the safe, high-efficiency, low-cost and high-precision thickness measurement of pipelines becomes urgent.
Disclosure of Invention
The invention aims to provide a method and a system for measuring the thickness of a metal pipeline.
In order to achieve the purpose, the invention provides the following scheme:
a metal pipe thickness measurement method, comprising:
acquiring an impedance-frequency curve group corresponding to the thickness of each set pipeline; the set of impedance-frequency curves comprises a plurality of impedance-frequency curves; the impedance-frequency curve is a curve that the imaginary part value of the relative impedance increment of the detection coil changes along with the frequency value of the excitation signal under the set vertical elevation angle of the detection coil in the eddy current nondestructive detection device; one impedance-frequency curve in the impedance-frequency curve group corresponds to a set vertical elevation angle;
determining the rotation intersection point of each set pipeline thickness according to all impedance-frequency curve groups; the rotating intersection points are the intersection points of all impedance-frequency curves in the impedance-frequency curve group corresponding to the set pipeline thickness;
determining a cross point curve from the rotational cross points of all the set pipe thicknesses; the abscissa of the cross point curve is an excitation signal frequency value, and the ordinate of the cross point curve is an imaginary part value of the relative impedance increment;
determining a fitting equation of the thickness of the pipeline and the frequency value of the excitation signal according to the cross point curve;
and determining the thickness of the metal pipeline to be measured according to the fitting equation.
Optionally, determining the thickness of the metal pipe to be measured by the fitting equation specifically includes:
obtaining a thickness equation through inverse calculation according to the fitting equation; the fitting equation is f ═ H (T), and the thickness equation is T ═ H '(f), wherein T is the thickness of the pipeline to be measured, f is the frequency value of the excitation signal, and H' represents the inverse calculation of H;
acquiring an impedance-frequency curve group of a metal pipeline to be detected;
determining a rotation intersection point of the metal pipeline to be tested according to the impedance-frequency curve group of the metal pipeline to be tested;
determining a frequency value corresponding to a rotation intersection point of the metal pipeline to be detected;
and substituting the frequency value corresponding to the rotation intersection point of the metal pipeline to be measured into the thickness equation to obtain the thickness of the metal pipeline to be measured.
Optionally, the obtaining of the impedance-frequency curve group corresponding to each set pipe thickness specifically includes:
and under the set horizontal rotation angle and the set lift-off of the detection coil, changing the vertical elevation angle of the detection coil in a specific vertical elevation angle interval, and determining impedance-frequency curves under each vertical elevation angle to obtain an impedance-frequency curve group with the set pipe thickness.
Optionally, the method includes, under a set horizontal rotation angle and a set lift-off of the detection coil, changing a vertical elevation angle of the detection coil within a specific vertical elevation angle interval, and determining an impedance-frequency curve at each vertical elevation angle to obtain an impedance-frequency curve group of a set pipe thickness, specifically including:
determining a current set vertical elevation angle of the detection coil;
changing the excitation signal frequency value of the eddy current nondestructive testing device within a specific frequency value interval under the set horizontal rotation angle, the set lift-off and the current set vertical elevation angle of the detection coil to obtain an impedance-frequency curve under the current set vertical elevation angle corresponding to the set pipe thickness;
and obtaining an impedance-frequency curve group of the set pipeline thickness according to the impedance-frequency curves at all vertical elevation angles.
Optionally, the intersection curve is determined by the rotation intersections of all the set pipe thicknesses, specifically: and connecting all the rotating cross points with the set pipe thickness in sequence by using a smooth curve to obtain the cross point curve.
A metal pipe thickness measurement system, comprising:
the curve group acquisition module is used for acquiring an impedance-frequency curve group corresponding to the thickness of each set pipeline; the set of impedance-frequency curves comprises a plurality of impedance-frequency curves; the impedance-frequency curve is a curve that the imaginary part value of the relative impedance increment of the detection coil changes along with the frequency value of the excitation signal under the set vertical elevation angle of the detection coil in the eddy current nondestructive detection device; one impedance-frequency curve in the impedance-frequency curve group corresponds to a set vertical elevation angle;
the rotating intersection point determining module is used for determining the rotating intersection points of the set pipe thicknesses according to all the impedance-frequency curve groups; the rotating intersection points are the intersection points of all impedance-frequency curves in the impedance-frequency curve group corresponding to the set pipeline thickness;
the intersection curve determining module is used for determining an intersection curve by the rotating intersections of all the set pipe thicknesses; the abscissa of the cross point curve is an excitation signal frequency value, and the ordinate of the cross point curve is an imaginary part value of the relative impedance increment;
the fitting equation determining module is used for determining a fitting equation of the pipeline thickness and the excitation signal frequency value according to the cross point curve;
and the pipe thickness calculation module is used for determining the thickness of the metal pipe to be measured according to the fitting equation.
Optionally, the pipe thickness calculating module includes:
the thickness equation calculation unit is used for obtaining a thickness equation through inverse calculation according to the fitting equation; the fitting equation is f ═ H (T), and the thickness equation is T ═ H '(f), wherein T is the thickness of the pipeline to be measured, f is the frequency value of the excitation signal, and H' represents the inverse calculation of H;
the device comprises a to-be-tested pipeline curve group acquisition unit, a to-be-tested pipeline curve group acquisition unit and a to-be-tested pipeline curve group acquisition unit, wherein the to-be-tested pipeline curve group acquisition unit is used for acquiring an impedance-frequency curve group of a to-be-tested metal pipeline;
the device comprises a to-be-tested pipeline rotation intersection point acquisition unit, a to-be-tested pipeline rotation intersection point acquisition unit and a to-be-tested pipeline rotation intersection point acquisition unit, wherein the to-be-tested pipeline rotation intersection point acquisition unit is used for determining the rotation intersection point of the to-be-tested metal pipeline according to the impedance-frequency curve;
the device comprises a to-be-detected pipeline frequency value acquisition unit, a frequency value acquisition unit and a frequency value generation unit, wherein the to-be-detected pipeline frequency value acquisition unit is used for determining a frequency value corresponding to a rotating intersection point of a to-be-detected metal pipeline;
and the to-be-measured pipeline thickness calculating unit is used for substituting the frequency value corresponding to the rotation intersection point of the to-be-measured metal pipeline into the thickness equation to obtain the thickness of the to-be-measured metal pipeline.
Optionally, the curve group obtaining module includes: and the set pipeline thickness impedance-frequency curve group acquisition unit is used for changing the vertical elevation angle of the detection coil in a specific vertical elevation angle interval under the set horizontal rotation angle and the set lift-off of the detection coil, determining impedance-frequency curves under each vertical elevation angle and obtaining an impedance-frequency curve group of the set pipeline thickness.
Optionally, the set pipe thickness impedance-frequency curve group obtaining unit includes:
a vertical elevation angle determining subunit, configured to determine a currently set vertical elevation angle of the detection coil;
the impedance-frequency curve determining subunit is used for changing the excitation signal frequency value of the eddy current nondestructive testing device within a specific frequency value interval under the set horizontal rotation angle, the set lift-off angle and the current set vertical elevation angle of the detection coil to obtain an impedance-frequency curve under the current set vertical elevation angle corresponding to the set pipe thickness;
and the set pipeline thickness impedance-frequency curve group acquisition subunit is used for acquiring an impedance-frequency curve group of the set pipeline thickness according to the impedance-frequency curves at all vertical elevation angles.
Optionally, the intersection curve determining module includes: and the intersection curve determining unit is used for connecting all the rotating intersections with the set pipe thickness in sequence by using the smooth curve to obtain the intersection curve.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects: the method is a safe, efficient, low-cost and high-precision nondestructive detection method for the thickness of the metal pipeline, and the thickness of the metal pipeline is obtained through further inversion calculation by utilizing the corresponding relation between the characteristic value (the frequency value corresponding to the rotary intersection) in the detection coil relative impedance increment frequency domain signal and the thickness of the metal pipeline based on the relation that the detection coil relative impedance increment signal is highly sensitive to the thickness of the pipeline.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a flow chart of a method for measuring the thickness of a metal pipe according to embodiment 1 of the present invention;
FIG. 2 is a schematic diagram of an impedance-frequency curve set of the same metal pipeline in example 1 of the present invention;
FIG. 3 is a schematic diagram of a set of impedance-frequency curves of different metal pipes according to example 1 of the present invention;
fig. 4 is a schematic structural diagram of a metal pipe thickness measuring system according to embodiment 2 of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a method and a system for measuring the thickness of a metal pipeline. The method is a safe, efficient, low-cost and high-precision nondestructive detection method for the thickness of the metal pipeline, and the thickness of the metal pipeline is obtained through further inversion calculation by utilizing the corresponding relation between the characteristic value (the frequency value corresponding to the rotary intersection) in the detection coil relative impedance increment frequency domain signal and the thickness of the metal pipeline based on the relation that the detection coil relative impedance increment signal is highly sensitive to the thickness of the pipeline.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Example 1
As shown in fig. 1, a method for measuring the thickness of a metal pipe includes:
step 101: and acquiring an impedance-frequency curve group corresponding to the thickness of each set pipeline.
The set of impedance-frequency curves comprises a plurality of impedance-frequency curves; the impedance-frequency curve is a curve that the imaginary part value of the relative impedance increment of the detection coil changes along with the frequency value of the excitation signal under the set vertical elevation angle of the detection coil in the eddy current nondestructive detection device; one impedance-frequency curve in the impedance-frequency curve group corresponds to a set vertical elevation angle.
The step 101 specifically includes:
b1: and under the set horizontal rotation angle and the set lift-off of the detection coil, changing the vertical elevation angle of the detection coil in a specific vertical elevation angle interval, and determining impedance-frequency curves under each vertical elevation angle to obtain an impedance-frequency curve group with the set pipe thickness.
C1: determining a current set vertical elevation angle of the detection coil.
C2: and changing the frequency value of the excitation signal of the eddy current nondestructive testing device within a specific frequency value interval under the set horizontal rotation angle, the set lift-off and the current set vertical elevation angle of the detection coil to obtain an impedance-frequency curve corresponding to the set pipe thickness under the current set vertical elevation angle.
C3: and obtaining an impedance-frequency curve group of the set pipeline thickness according to the impedance-frequency curves at all vertical elevation angles.
Step 102: and determining the rotation intersection point of each set pipeline thickness according to all impedance-frequency curve groups.
The rotating intersection points are the intersection points of all impedance-frequency curves in the impedance-frequency curve group corresponding to the set pipeline thickness;
step 103: the intersection curve is determined from the rotational intersections of all set pipe thicknesses.
The abscissa of the cross-point curve is the value of the excitation signal frequency and the ordinate of the cross-point curve is the value of the imaginary part of the relative impedance increment.
The step 103 specifically includes:
d1: and connecting all the rotating cross points with the set pipe thickness in sequence by using a smooth curve to obtain the cross point curve.
Step 104: and determining a fitting equation of the pipe thickness and the excitation signal frequency value according to the cross point curve.
Step 105: and determining the thickness of the metal pipeline to be measured according to the fitting equation.
The step 105 specifically includes:
e1: obtaining a thickness equation through inverse calculation according to the fitting equation; the fitting equation is f ═ H (T), and the thickness equation is T ═ H '(f), wherein T is the thickness of the pipeline to be measured, f is the frequency value of the excitation signal, and H' represents the inverse calculation of H.
E2: and acquiring an impedance-frequency curve group of the metal pipeline to be tested.
E3: and determining the rotation intersection point of the metal pipeline to be tested according to the impedance-frequency curve group of the metal pipeline to be tested.
E4: and determining the frequency value corresponding to the rotation intersection point of the metal pipeline to be detected.
E5: and substituting the frequency value corresponding to the rotation intersection point of the metal pipeline to be measured into the thickness equation to obtain the thickness of the metal pipeline to be measured.
The implementation process of the embodiment is totally divided into a preparation stage, an actual measurement stage and a thickness calculation and acquisition stage.
A preparation stage: firstly, preparing a group of metal pipeline standard parts with different thicknesses, carrying out thickness measurement on the group of standard parts by using an eddy current nondestructive testing device, developing and analyzing measurement signals in a frequency domain to obtain signal rotation cross points with different pipeline thicknesses, connecting the signal rotation cross points to form a cross point curve, obtaining the relation between the pipeline thickness corresponding to the signal rotation cross points and the corresponding excitation signal frequency value by the cross point curve, further obtaining a unary fitting equation f (H) (T) of the metal pipeline thickness relative to the current excitation frequency, and finally carrying out inverse calculation on H (T) to obtain a thickness equation T (H' (f).
And (3) actual measurement stage: the eddy current nondestructive testing device is used for carrying out multi-angle and multi-azimuth measurement on the metal pipeline to be tested to obtain an impedance-frequency curve group, and further obtaining the frequency value of a rotating cross point corresponding to the impedance-frequency curve group.
And a thickness calculation obtaining stage: and the frequency value obtained in the actual measurement stage is substituted into an equation T ═ H' (f), so that the thickness of the metal pipeline to be measured can be obtained quickly and accurately.
The specific implementation process of the embodiment is as follows:
s1: the eddy current nondestructive testing device carries out multi-angle and multi-azimuth measurement on the metal pipeline to be tested to obtain an impedance-frequency curve group.
The S1 specifically includes:
a1: the method comprises the following steps that an eddy current nondestructive testing device is used for actually testing a pipeline with set thickness, and as a detection coil can be placed in any mode, the placing mode of the coil can be accurately described according to three groups of parameters, namely a horizontal rotation angle beta of the coil, a vertical elevation angle gamma of the coil and a lifting-off d of the coil; fixing beta and d, changing gamma from 0 degree to 90 degrees in sequence, detecting the change condition of the relative impedance increment of the detection coil at each different gamma angle in a current excitation frequency value interval of 0hz to 100000hz, and obtaining a plurality of experimental data images of the relative impedance increment of the coil at different gamma angles relative to different current excitation frequency values.
A2: in the experimental data image of a1, the relative impedance increment has two contents of a real part and an imaginary part, and we find that in the same metal pipe, the data lines in the current excitation frequency value interval of 0hz to 100000hz intersect at a point where the relative impedance increment imaginary part is under different γ angles under the condition of the same β and d parameters by the detection coil, as shown in fig. 2, we temporarily name the point as the rotation intersection point of the impedance increment signal.
A3: we change a metal pipe and continue to repeat the processes of a1 and a2, and still find the rotation crossing point of the signal at the relative impedance increment imaginary part, only the frequency value is different, but the relative impedance increment imaginary part is almost unchanged.
S2: we further examined a set of metal pipes of different thicknesses, and presented the signal rotation crossing points of each metal pipe in the same graph, and found a crossing point curve L, as shown in fig. 3.
S3: the obtained curve L is composed of signal rotation cross points of metal pipelines with different thicknesses, so that the curve L can be used as a characteristic line for representing the thickness of the metal pipeline; further enabling the current excitation frequency value (namely the X-axis numerical value) corresponding to each rotation intersection point to correspond to the thickness of each pipeline, and obtaining a fitting equation f ═ H (T) of the frequency value corresponding to each rotation intersection point and the thickness of the corresponding pipeline; this is a one-dimensional N (unknown, determined from the actual data of the specific curve L) order equation.
S4: the fitting equation f is inverted to H (T), and the thickness equation T is obtained as H' (f).
S5: a metal pipeline with the thickness to be measured is subjected to an A1 and A2 two-step experimental test, and a frequency value f corresponding to a signal rotation intersection point of the metal pipeline is found1。
S6: will f is1And the high-precision metal pipeline thickness data can be obtained by directly substituting the T ═ H' (f) formula.
In the embodiment, the thickness of the metal pipeline is detected by using the eddy current nondestructive testing method, the square wave signal is selected as the excitation signal of the pulse eddy current, the corresponding relation between the characteristic value in the frequency domain and the thickness of the metal pipeline is found out through simulation modeling, the thickness of the metal pipeline is obtained through further inversion calculation, and experimental data shows that the method can realize the nondestructive testing of the thickness of the metal pipeline with high efficiency, low cost and high precision.
Example 2
As shown in fig. 4, a metal pipe thickness measuring system includes:
a curve group obtaining module 201, configured to obtain an impedance-frequency curve group corresponding to each set pipe thickness; the set of impedance-frequency curves comprises a plurality of impedance-frequency curves; the impedance-frequency curve is a curve that the imaginary part value of the relative impedance increment of the detection coil changes along with the frequency value of the excitation signal under the set vertical elevation angle of the detection coil in the eddy current nondestructive detection device; one impedance-frequency curve in the impedance-frequency curve group corresponds to a set vertical elevation angle.
The curve group acquiring module 201 specifically includes:
and the set pipeline thickness impedance-frequency curve group acquisition unit is used for changing the vertical elevation angle of the detection coil in a specific vertical elevation angle interval under the set horizontal rotation angle and the set lift-off of the detection coil, determining impedance-frequency curves under each vertical elevation angle and obtaining an impedance-frequency curve group of the set pipeline thickness.
The set pipeline thickness impedance-frequency curve group obtaining unit specifically comprises:
a vertical elevation angle determining subunit, configured to determine a currently set vertical elevation angle of the detection coil;
and the impedance-frequency curve determining subunit is used for changing the excitation signal frequency value of the eddy current nondestructive testing device within a specific frequency value interval under the set horizontal rotation angle, the set lift-off angle and the current set vertical elevation angle of the detection coil to obtain an impedance-frequency curve under the current set vertical elevation angle corresponding to the set pipe thickness.
And the set pipeline thickness impedance-frequency curve group acquisition subunit is used for acquiring an impedance-frequency curve group of the set pipeline thickness according to the impedance-frequency curves at all vertical elevation angles.
A rotation intersection determining module 202, configured to determine a rotation intersection of each set pipe thickness according to all impedance-frequency curve groups; the rotation intersection point is the intersection point of all impedance-frequency curves in the impedance-frequency curve group corresponding to the set pipeline thickness.
An intersection curve determining module 203 for determining an intersection curve from the rotational intersections of all the set pipe thicknesses; the abscissa of the cross-point curve is the value of the excitation signal frequency and the ordinate of the cross-point curve is the value of the imaginary part of the relative impedance increment.
The intersection curve determining module 203 specifically includes: and the intersection curve determining unit is used for connecting all the rotating intersections with the set pipe thickness in sequence by using the smooth curve to obtain the intersection curve.
And a fitting equation determining module 204, configured to determine a fitting equation of the pipe thickness and the excitation signal frequency value according to the intersection point curve.
And the pipe thickness calculation module 205 is used for determining the thickness of the metal pipe to be measured according to the fitting equation.
The pipe thickness calculation module 205 specifically includes:
the thickness equation calculation unit is used for obtaining a thickness equation through inverse calculation according to the fitting equation; the fitting equation is f ═ H (T), and the thickness equation is T ═ H '(f), wherein T is the thickness of the pipeline to be measured, f is the frequency value of the excitation signal, and H' represents the inverse calculation of H.
And the to-be-tested pipeline curve group acquisition unit is used for acquiring the impedance-frequency curve group of the to-be-tested metal pipeline.
And the rotation intersection point acquisition unit of the to-be-detected pipeline is used for determining the rotation intersection point of the to-be-detected metal pipeline according to the impedance-frequency curve group of the to-be-detected metal pipeline.
And the frequency value acquisition unit of the to-be-detected pipeline is used for determining the frequency value corresponding to the rotation intersection point of the to-be-detected metal pipeline.
And the to-be-measured pipeline thickness calculating unit is used for substituting the frequency value corresponding to the rotation intersection point of the to-be-measured metal pipeline into the thickness equation to obtain the thickness of the to-be-measured metal pipeline.
The technical problem solved by the invention is as follows: based on the relation that the detection coil is highly sensitive to the thickness of the pipeline relative impedance increment signal, the corresponding relation between the characteristic value (frequency value corresponding to the rotary intersection point) in the detection coil relative impedance increment frequency domain signal and the thickness of the metal pipeline is utilized, the thickness of the metal pipeline is obtained through further inversion calculation, and the non-ferromagnetic metal pipeline is subjected to high-efficiency thickness measurement in a freely-placed mode, wherein the high-efficiency thickness measurement is safe, lossless, high in precision and low in cost.
The principle of the invention is as follows: the detection coil is placed at will, mathematical modeling is carried out, analytical solutions of all relevant physical quantities are accurately given through a model, and non-ferromagnetic pipelines are simulated based on the analytical solutions. In the frequency band, the influence of the thickness of the pipeline on the observation result is represented by the obvious change of the abscissa position of the rotating intersection point of the impedance relative increment signal curve, namely, the frequency of the rotating intersection point of the impedance relative increment curve is lower as the thickness is smaller, and under the condition that other parameters are the same, the frequency and the wall thickness of a tested piece have a one-to-one correspondence relationship, so that the frequency domain signal of the relative impedance increment can be used as the thickness characteristic information of the metal pipeline for thickness measurement, and therefore, in the experiment, the numerical value of the thickness of the pipeline to be measured can be accurately obtained only by bringing the frequency value corresponding to the rotating intersection point of the pipeline to be measured into a corresponding analytical solution.
Compared with the prior art, the invention has the advantages that: the method solves the error defect that the inclination of the coil possibly brings about the measurement result in the placement type nondestructive testing, can realize the wall thickness measurement of the metal pipeline with low cost, high efficiency and high precision by using the characteristic point of the relative impedance increment signal imaginary part rotation cross point, and can realize the nondestructive testing of the thickness of the metal pipeline with high efficiency, low cost and high precision by displaying the experimental data.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (10)
1. A method for measuring the thickness of a metal pipe is characterized by comprising the following steps:
acquiring an impedance-frequency curve group corresponding to the thickness of each set pipeline; the set of impedance-frequency curves comprises a plurality of impedance-frequency curves; the impedance-frequency curve is a curve that the imaginary part value of the relative impedance increment of the detection coil changes along with the frequency value of the excitation signal under the set vertical elevation angle of the detection coil in the eddy current nondestructive detection device; one impedance-frequency curve in the impedance-frequency curve group corresponds to a set vertical elevation angle;
determining the rotation intersection point of each set pipeline thickness according to all impedance-frequency curve groups; the rotating intersection points are the intersection points of all impedance-frequency curves in the impedance-frequency curve group corresponding to the set pipeline thickness;
determining a cross point curve from the rotational cross points of all the set pipe thicknesses; the abscissa of the cross point curve is an excitation signal frequency value, and the ordinate of the cross point curve is an imaginary part value of the relative impedance increment;
determining a fitting equation of the thickness of the pipeline and the frequency value of the excitation signal according to the cross point curve;
and determining the thickness of the metal pipeline to be measured according to the fitting equation.
2. The method according to claim 1, wherein the determining the thickness of the metal pipe to be measured by the fitting equation specifically comprises:
obtaining a thickness equation through inverse calculation according to the fitting equation; the fitting equation is f ═ H (T), and the thickness equation is T ═ H '(f), wherein T is the thickness of the pipeline to be measured, f is the frequency value of the excitation signal, and H' represents the inverse calculation of H;
acquiring an impedance-frequency curve group of a metal pipeline to be detected;
determining a rotation intersection point of the metal pipeline to be tested according to the impedance-frequency curve group of the metal pipeline to be tested;
determining a frequency value corresponding to a rotation intersection point of the metal pipeline to be detected;
and substituting the frequency value corresponding to the rotation intersection point of the metal pipeline to be measured into the thickness equation to obtain the thickness of the metal pipeline to be measured.
3. The method for measuring the thickness of the metal pipeline according to claim 1, wherein the obtaining of the impedance-frequency curve group corresponding to each set pipeline thickness specifically comprises:
and under the set horizontal rotation angle and the set lift-off of the detection coil, changing the vertical elevation angle of the detection coil in a specific vertical elevation angle interval, and determining impedance-frequency curves under each vertical elevation angle to obtain an impedance-frequency curve group with the set pipe thickness.
4. The method according to claim 3, wherein the method for measuring the thickness of the metal pipe comprises the steps of changing the vertical elevation angle of the detection coil within a specific vertical elevation angle interval under the set horizontal rotation angle and the set lift-off of the detection coil, determining impedance-frequency curves at each vertical elevation angle, and obtaining an impedance-frequency curve group of the set pipe thickness, and specifically comprises the following steps:
determining a current set vertical elevation angle of the detection coil;
changing the excitation signal frequency value of the eddy current nondestructive testing device within a specific frequency value interval under the set horizontal rotation angle, the set lift-off and the current set vertical elevation angle of the detection coil to obtain an impedance-frequency curve under the current set vertical elevation angle corresponding to the set pipe thickness;
and obtaining an impedance-frequency curve group of the set pipeline thickness according to the impedance-frequency curves at all vertical elevation angles.
5. The method according to claim 1, wherein the intersection curve is determined from the rotational intersections of all the set pipe thicknesses, and specifically comprises: and connecting all the rotating cross points with the set pipe thickness in sequence by using a smooth curve to obtain the cross point curve.
6. A metal pipe thickness measurement system, comprising:
the curve group acquisition module is used for acquiring an impedance-frequency curve group corresponding to the thickness of each set pipeline; the set of impedance-frequency curves comprises a plurality of impedance-frequency curves; the impedance-frequency curve is a curve that the imaginary part value of the relative impedance increment of the detection coil changes along with the frequency value of the excitation signal under the set vertical elevation angle of the detection coil in the eddy current nondestructive detection device; one impedance-frequency curve in the impedance-frequency curve group corresponds to a set vertical elevation angle;
the rotating intersection point determining module is used for determining the rotating intersection points of the set pipe thicknesses according to all the impedance-frequency curve groups; the rotating intersection points are the intersection points of all impedance-frequency curves in the impedance-frequency curve group corresponding to the set pipeline thickness;
the intersection curve determining module is used for determining an intersection curve by the rotating intersections of all the set pipe thicknesses; the abscissa of the cross point curve is an excitation signal frequency value, and the ordinate of the cross point curve is an imaginary part value of the relative impedance increment;
the fitting equation determining module is used for determining a fitting equation of the pipeline thickness and the excitation signal frequency value according to the cross point curve;
and the pipe thickness calculation module is used for determining the thickness of the metal pipe to be measured according to the fitting equation.
7. The metal pipe thickness measurement system of claim 6, wherein the pipe thickness calculation module comprises:
the thickness equation calculation unit is used for obtaining a thickness equation through inverse calculation according to the fitting equation; the fitting equation is f ═ H (T), and the thickness equation is T ═ H '(f), wherein T is the thickness of the pipeline to be measured, f is the frequency value of the excitation signal, and H' represents the inverse calculation of H;
the device comprises a to-be-tested pipeline curve group acquisition unit, a to-be-tested pipeline curve group acquisition unit and a to-be-tested pipeline curve group acquisition unit, wherein the to-be-tested pipeline curve group acquisition unit is used for acquiring an impedance-frequency curve group of a to-be-tested metal pipeline;
the device comprises a to-be-tested pipeline rotation intersection point acquisition unit, a to-be-tested pipeline rotation intersection point acquisition unit and a to-be-tested pipeline rotation intersection point acquisition unit, wherein the to-be-tested pipeline rotation intersection point acquisition unit is used for determining the rotation intersection point of the to-be-tested metal pipeline according to the impedance-frequency curve;
the device comprises a to-be-detected pipeline frequency value acquisition unit, a frequency value acquisition unit and a frequency value generation unit, wherein the to-be-detected pipeline frequency value acquisition unit is used for determining a frequency value corresponding to a rotating intersection point of a to-be-detected metal pipeline;
and the to-be-measured pipeline thickness calculating unit is used for substituting the frequency value corresponding to the rotation intersection point of the to-be-measured metal pipeline into the thickness equation to obtain the thickness of the to-be-measured metal pipeline.
8. The metal pipe thickness measurement system of claim 6, wherein said curve group acquisition module comprises:
and the set pipeline thickness impedance-frequency curve group acquisition unit is used for changing the vertical elevation angle of the detection coil in a specific vertical elevation angle interval under the set horizontal rotation angle and the set lift-off of the detection coil, determining impedance-frequency curves under each vertical elevation angle and obtaining an impedance-frequency curve group of the set pipeline thickness.
9. The metal pipe thickness measuring system of claim 8, wherein said set pipe thickness impedance-frequency curve group obtaining unit comprises:
a vertical elevation angle determining subunit, configured to determine a currently set vertical elevation angle of the detection coil;
the impedance-frequency curve determining subunit is used for changing the excitation signal frequency value of the eddy current nondestructive testing device within a specific frequency value interval under the set horizontal rotation angle, the set lift-off angle and the current set vertical elevation angle of the detection coil to obtain an impedance-frequency curve under the current set vertical elevation angle corresponding to the set pipe thickness;
and the set pipeline thickness impedance-frequency curve group acquisition subunit is used for acquiring an impedance-frequency curve group of the set pipeline thickness according to the impedance-frequency curves at all vertical elevation angles.
10. The metal pipe thickness measurement system of claim 6, wherein said intersection curve determination module comprises:
and the intersection curve determining unit is used for connecting all the rotating intersections with the set pipe thickness in sequence by using the smooth curve to obtain the intersection curve.
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