CN111044605A - Method and device for magnetic flux leakage detection lift-off compensation and defect depth analysis - Google Patents
Method and device for magnetic flux leakage detection lift-off compensation and defect depth analysis Download PDFInfo
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Abstract
The invention discloses a method and a device for magnetic flux leakage detection lift-off compensation and defect depth analysis, wherein the method comprises the following steps: acquiring the height difference of the two triaxial magnetic field measurement chips in the normal direction; acquiring magnetic field values of two triaxial magnetic field measurement chips under current lift-off and height difference; carrying out magnetic field conversion variable on the magnetic field values of the two triaxial magnetic field measurement chips to obtain a first tangential component, a first normal component, a second tangential component and a second normal component; calculating to obtain a first depth lift-off composite variable and a second depth lift-off composite variable according to the two tangential components and the two normal components; respectively calculating the lift-off values and the current defect depths of the current two triaxial magnetic field measurement chips by using the two depth lift-off composite variables; and (4) performing compensation calculation on the current magnetic field value by using the defect depth to obtain the magnetic field value under the target lift-off value. The method can analyze the defect depth under the deviation and fluctuation lift-off values and compensate the lift-off in real time to obtain the defect magnetic signal.
Description
Technical Field
The invention relates to the technical field of nondestructive testing, in particular to a method and a device for magnetic flux leakage testing lift-off compensation and defect depth analysis.
Background
Oil and gas pipelines, oil storage tank floors and the like are usually made of ferromagnetic materials. In terms of nondestructive testing of ferromagnetic materials, magnetic flux leakage testing is one of the most commonly used online testing techniques, and mainly includes performing saturation magnetization on a tested piece, and reversely solving size information of a defect by detecting distribution and size of a leakage magnetic field at the defect. However, the measured defect leakage signal is affected by many factors, including defect size, magnetization, three-axis magnetic field measurement chip lift-off value, etc. The problem of optimizing the compensation of the lift-off value of the triaxial magnetic field measurement chip and the lift-off effect of the leakage magnetic signal of the defect is always the key and difficult point of the defect detection technology.
In the related art, the main method for solving the defect magnetic leakage signal lift-off effect is as follows: comprehensively considering vibration noise caused by lift-off reduction and electromagnetic noise caused by lift-off increase to obtain the optimal lift-off value of the triaxial magnetic field measurement chip; according to the observation, the defect magnetic leakage signal is concluded to have a depth combination effect, and the compensation of the special lift-off value is realized based on the depth combination effect; there is a primary filtering that uses a hardware differential circuit to achieve lift-off. However, in the actual detection process, due to vibration, mechanical offset and other reasons, the lift-off value of the three-axis magnetic field measurement chip may deviate from the original design value and continuously change in the detection process, and most of the above methods can only optimize or compensate the fixed lift-off value, and cannot simultaneously solve the problems of the lift-off value offset and the continuous change of the lift-off value.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art.
Therefore, an object of the present invention is to provide a method for magnetic flux leakage detection lift-off compensation and defect depth analysis, which can analyze the defect depth under offset and fluctuating lift-off values and compensate the lift-off in real time to obtain a defect magnetic signal.
Another object of the present invention is to provide a magnetic flux leakage detection lift-off compensation and defect depth analysis device.
In order to achieve the above object, an embodiment of the present invention provides a method for magnetic flux leakage detection lift-off compensation and defect depth analysis, including the following steps: acquiring the height difference of the two triaxial magnetic field measurement chips in the normal direction; acquiring magnetic field values of the two triaxial magnetic field measurement chips under current lift-off and height difference, wherein the magnetic field values comprise a first tangential component B of a first triaxial magnetic field measurement chipx(d1) And a first normal component By(d1) Second tangential component B of a second three-axis magnetic field measurement chipx(d2) And a second normal component By(d2) (ii) a Carrying out magnetic field conversion variable on the magnetic field values of the two triaxial magnetic field measurement chips to obtain a first tangential component A of the magnetic field conversion variablex(d1) And a first normal component Ry(d1) Second tangential component Ax(d2) And a second normal component Ry(d2) (ii) a According to the first tangential component Ax(d1) And said first normal component Ry(d1) Said second tangential component Ax(d2) And said second normal component Ry(d2) And calculating to obtain a first depth lift-off composite variable v (d)1) And a second depth lift-off complex variable v (d)2) (ii) a Using the first depth to lift off a complex variable v (d)1) And said second depth lift-off complex variable v (d)2) And calculating the lift-off value d of the current first triaxial magnetic field measurement chip1The lift-off value d of the second triaxial magnetic field measurement chip2And the current defect depth h; and performing compensation calculation on the magnetic field value under the current defect depth condition by using the current defect depth h to obtain the magnetic field value under the target lift-off value.
According to the method for magnetic flux leakage detection lift-off compensation and defect depth analysis, one-time calculation can be performed on each defect, and a real-time lift-off value in the detection process is solved; the calculation can be performed once on each defect, and the depth of the currently detected defect is calculated; the measured value of the magnetic field at the current lift-off can be converted to the magnetic field at the target lift-off.
In addition, the method for magnetic flux leakage detection lift-off compensation and defect depth analysis according to the above embodiment of the present invention may further have the following additional technical features:
further, in one embodiment of the present invention, the height difference is determined at the time of designing the probe device, and is kept unchanged after the probe device is manufactured, and the relationship is satisfied at any time during the detection process:
r＝d2-d1
wherein r is height difference, thickness of the three-axis magnetic field measurement chip is more than or equal to d1For the lift-off value of the first three-axis magnetic field measuring chip, d2The lift-off value of the chip is measured for the second three-axis magnetic field.
Further, in an embodiment of the invention, said first tangential component Bx(d1) The first normal component By(d1) Said second tangential component Bx(d2) And said second normal component By(d2) The magnetic field values at the edges of the defects are all obtained, and the width of the defects is obtained through the peak width value of the leakage magnetic field waveform.
Further, in one embodiment of the invention, the tangential component A of the magnetic field switching variable isx(y) and Ry(y) with the currently measured magnetic field Bx(y) and By(y) satisfies the following equation:
wherein A isx(y) comprises a first tangential component Ax(d1) And a second tangential component Ax(d2)，Ry(y) includes a first normal component Ry(d1) And a second normal component Ry(d2)，Bx(y) comprises a first tangential component Bx(d1) And a secondTangential component Bx(d2)，By(y) denotes a first normal component By(d1) And a second normal component By(d2)，μ0Is the magnetic permeability in air, σsIs the equivalent linear magnetic charge density of the surface of the defect.
Further, in one embodiment of the present invention, the depth lift-off complex variable v (y) and the magnetic field switching variable Ax(y)，Ry(y) satisfies the relationship:
wherein v (y) includes a first depth lift-off complex variable v (d)1) And a second depth lift-off complex variable v (d)2)，Ax(y) comprises a first tangential component Ax(d1) And a second tangential component Ax(d2)，Ry(y) includes a first normal component Ry(d1) And a second normal component Ry(d2)。
Further, in one embodiment of the present invention, the first depth lift-off complex variable v (d)1) And said second depth lift-off complex variable v (d)2) A lift-off value d from the current first triaxial magnetic field measurement chip1And a lift-off value d of the second three-axis magnetic field measurement chip2Satisfies the relationship:
further, in one embodiment of the present invention, the current defect depth h is a complex variable v (d) of the first depth lift-off1) And said second depth lift-off complex variable v (d)2) Currently, the lift-off value d of the first triaxial magnetic field measurement chip1And a lift-off value d of the second three-axis magnetic field measurement chip2Satisfy the shut-downComprises the following steps:
in order to achieve the above object, another embodiment of the present invention provides an apparatus for magnetic flux leakage detection lift-off compensation and defect depth analysis, including: the device comprises two triaxial magnetic field measurement chips, a data processing unit and a data storage unit, wherein the two triaxial magnetic field measurement chips are vertically distributed, are positioned above a tested piece and are used for acquiring a magnetic field value under the current condition that the probe is inclined; the data processing unit is respectively connected with the two triaxial magnetic field measurement chips and is used for analyzing and processing the magnetic field value under the current probe inclination condition to obtain a defect magnetic flux leakage signal under a correct posture; the data storage unit is connected with the data processing unit and used for storing the data of the data processing unit.
According to the magnetic flux leakage detection lift-off compensation and defect depth analysis device, each defect can be resolved once, and a real-time lift-off value in the detection process can be resolved; the calculation can be performed once on each defect, and the depth of the currently detected defect is calculated; the measured value of the magnetic field at the current lift-off can be converted to the magnetic field at the target lift-off.
In addition, the magnetic flux leakage detection lift-off compensation and defect depth analysis device according to the above embodiment of the present invention may further have the following additional technical features:
further, in an embodiment of the present invention, the method further includes: pole shoes or steel brushes, permanent magnets, iron yokes; the pole shoes or the steel brushes are positioned on two sides of the two triaxial magnetic field measurement chips, are symmetrically distributed and are used for restricting the magnetic field distribution between the magnetic flux leakage detector and the test piece; the permanent magnets comprise a permanent magnet with a downward S pole and a permanent magnet with a downward N pole, are positioned above the pole shoe or the steel brush, are symmetrically distributed on two sides of the two triaxial magnetic field measurement chips and are used for magnetizing the tested piece; and the iron yoke is positioned above the permanent magnet and the two triaxial magnetic field measurement chips and is used for constraining the magnetic field distribution inside the magnetic flux leakage detector and reducing a background magnetic field.
Further, in an embodiment of the present invention, the data processing unit is specifically configured to: carrying out magnetic field conversion variable on the magnetic field values of the two triaxial magnetic field measurement chips to obtain a first tangential component Ax(d1) And a first normal component Ry(d1) Second tangential component Ax(d2) And a second normal component Ry(d2) (ii) a According to the first tangential component Ax(d1) And said first normal component Ry(d1) Said second tangential component Ax(d2) And said second normal component Ry(d2) And calculating to obtain a first depth lift-off composite variable v (d)1) And a second depth lift-off complex variable v (d)2) (ii) a Using the first depth to lift off a complex variable v (d)1) And said second depth lift-off complex variable v (d)2) And calculating the lift-off value d of the current first triaxial magnetic field measurement chip1The lift-off value d of the second triaxial magnetic field measurement chip2And the current defect depth h; and performing compensation calculation on the magnetic field value under the current defect depth condition by using the current defect depth h to obtain the magnetic field value under the target lift-off value.
Additional aspects and advantages 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
The foregoing and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a flowchart of a method for magnetic flux leakage detection lift-off compensation and defect depth analysis according to an embodiment of the present invention (the variable symbols are not labeled in the figure);
FIG. 2 is a schematic diagram of a position parameter between a dual magnetic measurement chip and a tested piece according to an embodiment of the present invention;
FIG. 3 is a schematic structural view of one embodiment of a probe apparatus according to the present invention;
FIG. 4 is a graph comparing magnetic field error results before and after lift-off compensation using the present invention, according to another embodiment of the present invention;
fig. 5 is a schematic structural diagram of a magnetic flux leakage detection lift-off compensation and defect depth analysis apparatus according to an embodiment of the present invention.
Description of reference numerals: 100-magnetic leakage detection lift-off compensation and defect depth analysis device, 1-tested piece made of ferromagnetic material, 2-pole shoe or steel brush, 4-permanent magnet with downward S pole, 5-permanent magnet with downward N pole, 6-iron yoke, 7-defect, 8-triaxial magnetic field measurement chip, 10-probe device data processing unit, 11-probe device data storage unit and 12-circuit board in one embodiment of probe device.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
The method and apparatus for magnetic leakage detection lift-off compensation and defect depth analysis according to the embodiments of the present invention will be described below with reference to the accompanying drawings, and first, the method for magnetic leakage detection lift-off compensation and defect depth analysis according to the embodiments of the present invention will be described with reference to the accompanying drawings.
Fig. 1 is a flowchart of a magnetic flux leakage detection lift-off compensation and defect depth analysis method according to an embodiment of the present invention.
As shown in fig. 1, the method for magnetic flux leakage detection lift-off compensation and defect depth analysis includes the following steps:
in step S1, the height difference in the normal direction of the two three-axis magnetic field measurement chips is acquired.
It should be noted that the normal direction is a direction perpendicular to the surface of the test piece, and in the embodiment of the present invention, the normal direction is represented by a subscript y.
Further, in one embodiment of the invention, the height difference is determined at the time of design of the probe device and remains unchanged after the probe device is manufactured, and the relationship is satisfied at any time during the inspection:
r＝d2-d1
wherein r is height difference, the minimum value is the thickness of the magnetic field measurement chip, usually 0.8-1 mm, the maximum value is 10mm, d1For the lift-off value of the first three-axis magnetic field measuring chip, d2The lift-off value of the chip is measured for the second three-axis magnetic field.
For example, as shown in fig. 2, the distance between two hall chips for magnetic field measurement is 1.8mm, which includes a thickness of a circuit board of 0.8mm and a half height of the two hall chips of 0.5mm (the magnetic field sensing point of the hall chip used in the embodiment is at the geometric center of the chip), and r satisfies the following equation at any time during the detection process:
r＝d2-d1
in step S2, magnetic field values of the two triaxial magnetic field measurement chips under the current lift-off and height difference are obtained, where the magnetic field values include the first tangential component B of the first triaxial magnetic field measurement chipx(d1) And a first normal component By(d1) Second tangential component B of a second three-axis magnetic field measurement chipx(d2) And a second normal component By(d2)。
It will be understood that the tangential direction in the embodiments of the present invention is along the direction of magnetization, and is denoted by the subscript x.
Further, in one embodiment of the invention, the first tangential component Bx(d1) First normal component By(d1) Second tangential component Bx(d2) And a second normal component By(d2) The magnetic field values at the edge of the defect are all obtained, and the width of the defect is obtained through the peak width value of the leakage magnetic field waveform.
Specifically, in the embodiment of the present invention, with the aid of two three-axis hall magnetic chips, the following results are respectively measured:
Bx(d1)＝24.2144Gs
By(d1)＝40.1351Gs
Bx(d2)＝12.236Gs
By(d2)＝-33.8227Gs
in step S3, a magnetic field conversion variable is performed on the magnetic field values of the two triaxial magnetic field measurement chips to obtain a first tangential component a of the magnetic field conversion variablex(d1) And a first normal component Ry(d1) Second tangential component Ax(d2) And a second normal component Ry(d2)。
Further, in one embodiment of the invention, the tangential component A in the magnetic field switching variable isx(y) and Ry(y) with the currently measured magnetic field Bx(y) and By(y) satisfies the following equation:
wherein A isx(y) comprises a first tangential component Ax(d1) And a second tangential component Ax(d2)，Ry(y) includes a first normal component Ry(d1) And a second normal component Ry(d2)，Bx(y) comprises a first tangential component Bx(d1) And a second tangential component Bx(d2)，By(y) denotes a first normal component By(d1) And a second normal component By(d2)，μ0Is the magnetic permeability in air, σsIs the equivalent linear magnetic charge density of the surface of the defect.
In step S4, according to the first tangential component Ax(d1) And a first normal component Ry(d1) Second tangential component Ax(d2) And a second normal component Ry(d2) Calculating to obtain the first depth lift-off compound variationQuantity v (d)1) And a second depth lift-off complex variable v (d)2)。
Further, the depth lift-off complex variable v (y) and the magnetic field transition variable Ax(y)，Ry(y) satisfies the relationship:
wherein v (y) includes a first depth lift-off complex variable v (d)1) And a second depth lift-off complex variable v (d)2)，Ax(y) comprises a first tangential component Ax(d1) And a second tangential component Ax(d2)，Ry(y) includes a first normal component Ry(d1) And a second normal component Ry(d2)。
In step S5, the complex variable v (d) is lifted off using the first depth1) And a second depth lift-off complex variable v (d)2) And calculating the lift-off value d of the current first triaxial magnetic field measurement chip1And the lift-off value d of the second triaxial magnetic field measurement chip2And the current defect depth h.
Further, in one embodiment of the present invention, the first depth lift-off complex variable v (d)1) And a second depth lift-off complex variable v (d)2) The lift-off value d from the current first triaxial magnetic field measurement chip1And the lift-off value d of the second triaxial magnetic field measurement chip2Satisfies the relationship:
that is, the complex variable v (d) is lifted off by depth1) And v (d)2) Can directly calculate the lift-off value d of the current first magnetic field measurement chip1And the lift-off value d of the second magnetic field measurement chip2(ii) a Current lift-off value d of first magnetic field measurement chip1The current lift-off value d of the second magnetic field measurement chip2Depth lift-off complex variable v (d)1) And the height difference r of the first magnetic field measurement chip and the second magnetic field measurement chip satisfies the following equation:
specifically, in the embodiment of the present invention, the current lift-off value d of the first magnetic field measurement chip is obtained through calculation12.11mm, the actual lift-off value is 2.18mm, and the error is only 3.21%; current lift-off value d of the second magnetic field measurement chip23.91mm, the actual lift-off value is 3.98mm, and the error is only 1.76%.
Further, in one embodiment of the present invention, the current defect depth h is a composite variable v (d) of the first depth lift-off1) And a second depth lift-off complex variable v (d)2) The lift-off value d of the current first triaxial magnetic field measurement chip1And the lift-off value d of the second triaxial magnetic field measurement chip2Satisfies the relationship:
that is, the complex variable v (d) is lifted off by depth1) And v (d)2) The current defect depth h can be directly calculated; composite variable v (d) of current defect depth h and depth lift-off1) And the height difference r of the first magnetic field measurement chip and the second magnetic field measurement chip satisfies the following equation:
in the present example, the current defect depth h was calculated to be 4.30mm, actually 4.50mm, with an error of only 4.44%.
In step S6, the magnetic field value under the current defect depth is compensated and calculated by using the current defect depth h, so as to obtain the magnetic field value under the target lift-off value.
Specifically, the lift-off compensation mainly comprises the steps of obtaining information such as defect width, depth and the like through the steps, and obtaining the relation between a magnetic field value under the target lift-off and a currently measured magnetic field value according to a magnetic dipole model.
That is, the current lift-off value d can be obtained using the current defect depth h obtained according to the above method1，d2The magnetic field size B measured by the lower magnetic field measurement chipx(d1)，Bx(d2)，By(d1) And By(d2) Obtaining a designed target lift-off value d by compensation calculation0Magnetic field value at bottom.
For example, in the embodiment of the present invention, the current lift-off value d of the first magnetic field measurement chip is measured12.18mm, second magnetic field measuring chip lift-off value d23.91mm, and converted to the target lift-off value d0At a magnetic field value of 2.90mm, the transverse component of the magnetic field is at a maximum Bx(d0) 58.57Gs, found 56.87Gs, error-3.00%; transverse component of magnetic field at defect width By(d0) Was-38.97 Gs, found to be-38.84 Gs, error-0.33%.
It can be understood that, in the embodiment of the present invention, the data processing unit is an STM32L4 single chip microcomputer of the ideological semiconductor company, the data storage unit is a W25Q64 series of the warpont company, and the storage space is 64M-bit, which can be selected by a person skilled in the art according to actual situations and is not limited specifically herein.
Therefore, the method solves the problem of compensating the magnetic field value under the design lift-off from the measured value by analyzing the defect depth under the lift-off value of the offset and the fluctuation, and has the advantages of simpler model solving, more definite scientific basis, better reliability and high calculation speed.
As shown in fig. 3, the method for magnetic flux leakage detection lift-off compensation and defect depth analysis according to the present invention will be described in detail below with an embodiment.
Step 1: the lift-off value d of the first magnetic field measurement chip is given1Obtaining the height difference r of the two magnetic field measurement chips in the normal direction, wherein the height difference r is 3 mm; in the present embodiment, the distance between the two hall chips for magnetic field measurement is 1.00mm, and r satisfies the following equation at any time during detection:
r＝d2-d1
step 2: two magnetic field measurement chips are utilized to obtain the magnetic field value under the current lift-off and height difference, including the tangential component Bx(d1) And Bx(d2) Normal component By(d1) And By(d2)；
And step 3: according to the obtained magnetic field values B at the two positionsx(d1)、Bx(d2)、By(d1)、By(d2) Obtaining the tangential component A of the magnetic field conversion variablex(d1) And Ax(d2) Normal component Ry(d1) And Ry(d2) (ii) a They satisfy the following equations, respectively:
wherein, mu0Is the magnetic permeability in air, σsIs the equivalent linear magnetic charge density of the surface of the defect.
And 4, step 4: according to the obtained magnetic field switching variable Ax(d1)，Ry(d1)，Ax(d2) And Ry(d2) Obtaining a depth lift-off composite variable v (d)1) And v (d)2) (ii) a Depth lift-off complex variable v (d)1) Magnetic field switching variable Ax(y)，Ry(y) satisfies the following equation:
and 5: using depth lift-off to complex variable v (d)1) And v (d)2) Can directly calculate the lift-off value d of the current first magnetic field measurement chip1And the lift-off value d of the second magnetic field measurement chip2(ii) a Current lift-off value d of first magnetic field measurement chip1The current lift-off value d of the second magnetic field measurement chip2Depth lift-off complex variable v (d)1) And the height difference r of the first magnetic field measurement chip and the second magnetic field measurement chip satisfies the following equation:
step 6: using depth lift-off to complex variable v (d)1) And v (d)2) The current defect depth h can be directly calculated; composite variable v (d) of current defect depth h and depth lift-off1) And the height difference r of the first magnetic field measurement chip and the second magnetic field measurement chip satisfies the following equation:
and 7: the current lift-off value d can be obtained by using the current defect depth h obtained by the method1，d2The magnetic field size B measured by the lower magnetic field measurement chipx(d1)、Bx(d2)、By(d1)、By(d2) Obtaining a target lift-off value d through compensation calculation0The value is the magnetic field at 2 mm. The results are shown in FIG. 4, where the transverse component of the magnetic field is at a maximum B before compensation using the probe of the present examplex(d0) The error of (2) is 51.15 percent, and the error after compensation is 6.51 percent; transverse component of magnetic field at defect width By(d0) Error 26.70% before compensation, after compensationThe error was 7.16%.
And 8: changing the lift-off value d of the first magnetic field measuring chip1At 4mm, steps two to seven were repeated and the results obtained are shown in FIG. 4, with the transverse component of the magnetic field at the maximum B, before compensation using the probe of the present examplex(d0) The error is 58.32 percent, and the error after compensation is 8.48 percent; transverse component of magnetic field at defect width By(d0) The error before compensation is 45.00 percent, and the error after compensation is 10.17 percent.
And step 9: changing the lift-off value d of the first magnetic field measuring chip1At 5mm, steps two to seven were repeated and the results obtained are shown in FIG. 4, with the transverse component of the magnetic field at the maximum B, before compensation using the probe of the present examplex(d0) 65.50% of the error, the error after compensation is 8.91%; transverse component of magnetic field at defect width By(d0) The error is 57.64% before compensation and 15.22% after compensation.
Step 10: changing the lift-off value d of the first magnetic field measuring chip1At 6mm, steps two to seven were repeated and the results obtained are shown in FIG. 4, with the transverse component of the magnetic field at the maximum B, before compensation using the probe of the present examplex(d0) 71.17% of the error, the error after compensation is 8.14%; transverse component of magnetic field at defect width By(d0) The error before compensation is 65.43 percent, and the error after compensation is 21.82 percent.
Step 11: changing the lift-off value d of the first magnetic field measuring chip1At 7mm, steps two to seven were repeated and the results obtained are shown in FIG. 4, with the transverse component of the magnetic field at the maximum B, before compensation using the probe of the present examplex(d0) The error is 75.66 percent, and the error after compensation is 4.82 percent; transverse component of magnetic field at defect width By(d0) The error before compensation is 71.69%, and the error after compensation is 26.22%. In this embodiment, the data processing unit is an STM32L4 single chip microcomputer of ideological semiconductor corporation, the data storage unit is a W25Q64 series of warpont corporation, and the storage space is 64M-bit.
The method solves the problem of analyzing the depth of the defect under the deviation and fluctuation lift-off values, the problem of compensating the magnetic field value under design lift-off from the measured value is solved, the measurement error caused by lift-off is greatly reduced, the solving model is simpler, the scientific basis is clearer, the reliability is better, and the calculating speed is high.
According to the method for magnetic flux leakage detection lift-off compensation and defect depth analysis provided by the embodiment of the invention, the magnetic field strength value at the edge of a defect is obtained through two magnetic field measurement chips, the magnetic field conversion variable is obtained through calculation, the depth lift-off composite variable is further obtained, finally the current lift-off value of the magnetic field measurement chip and the current depth of the detected defect are solved by combining the height difference of the magnetic field measurement chips in the normal direction, the detected magnetic field signal value is compensated to the designed lift-off value through the defect depth obtained through calculation, further the double magnetic field signal value obtained under a certain height difference through the vertical double magnetic field measurement chip can be confirmed and reversely deduced from the electromagnetic field principle, the model is simpler, the scientific basis is clearer, the reliability is better, the calculation speed is high, and the problem of defect depth analysis under the offset and fluctuating lift-off values is solved, the problem of the measured value compensate to the magnetic field value under the design lift-off is solved.
Next, a magnetic flux leakage detection lift-off compensation and defect depth analysis device according to an embodiment of the present invention will be described with reference to the drawings.
Fig. 5 is a magnetic flux leakage detection lift-off compensation and defect depth analysis apparatus according to an embodiment of the present invention.
As shown in fig. 5, the apparatus 100 includes: two triaxial magnetic field measurement chips 8 and 9, a data processing unit 10 and a data storage unit 11 are vertically distributed.
The two triaxial magnetic field measurement chips 8 and 9 are located above the tested piece 1 and used for acquiring the magnetic field value under the current probe inclination condition.
It should be noted that the tested piece 1 made of ferromagnetic material can be an oil and gas pipeline, a rail, a storage tank bottom plate, etc.
The data processing unit 10 is respectively connected with the two triaxial magnetic field measurement chips 8 and 9, and is used for analyzing and processing the magnetic field value entering under the current probe inclination condition to obtain a defect magnetic flux leakage signal under the correct posture.
The data storage unit 11 is connected to the data processing unit 10 and is used for storing data of the data processing unit 10.
Further, in an embodiment of the present invention, the data processing unit 10 is specifically configured to:
carrying out magnetic field conversion variable on the magnetic field values of the two triaxial magnetic field measurement chips to obtain a first tangential component Ax(d1) And a first normal component Ry(d1) Second tangential component Ax(d2) And a second normal component Ry(d2)；
According to a first tangential component Ax(d1) And a first normal component Ry(d1) Second tangential component Ax(d2) And a second normal component Ry(d2) And calculating to obtain a first depth lift-off composite variable v (d)1) And a second depth lift-off complex variable v (d)2)；
Lifting off a complex variable v (d) with a first depth1) And a second depth lift-off complex variable v (d)2) And calculating the lift-off value d of the current first triaxial magnetic field measurement chip1And the lift-off value d of the second triaxial magnetic field measurement chip2And the current defect depth h; and
and (4) performing compensation calculation on the magnetic field value under the current defect depth condition by using the current defect depth h to obtain the magnetic field value under the target lift-off value.
Further, the embodiment of the present invention further includes: the magnetic field leakage detector comprises pole shoes or steel brushes 2 and 3, permanent magnets 4 and 5 and an iron yoke 6, wherein the pole shoes or steel brushes 2 and 3 are positioned on two sides of two triaxial magnetic field measurement chips 8 and 9 and are symmetrically distributed and used for restricting the magnetic field distribution between the magnetic flux leakage detector and a test piece; the permanent magnets 4 and 5 comprise a permanent magnet with a downward S pole and a permanent magnet with a downward N pole, the permanent magnets are positioned above the pole shoes or the steel brushes 2 and 3, are symmetrically distributed on two sides of the two triaxial magnetic field measurement chips 8 and 9 and are used for magnetizing the tested piece 1; and the iron yoke 7 is positioned above the permanent magnets 4 and 5 and the two triaxial magnetic field measurement chips 2 and 3 and is used for restricting the magnetic field distribution inside the magnetic leakage detector and reducing the background magnetic field.
That is, the tested object 1 is magnetized by the permanent magnets 4 and 5 on both sides of the device, and when a defect occurs, a leakage magnetic field is generated, and the two magnetic field measuring cores 8 and 9 vertically distributed collect two magnetic field values under a certain height difference, and transmit the values to the data processing unit 10 and the storage unit 11. The data processing unit 10 can calculate the lift-off value of the current probe and the depth of the current detected defect by combining the magnetic field values measured by the two magnetic field measurement chips and the vertical distance between the two magnetic field measurement chips. Further, due to mechanical reasons such as vibration and the like, the situation that the lift-off may continuously deviate and fluctuate in the measurement process is solved, so that the magnetic field measured under the current deviation lift-off is compensated to the designed target lift-off value, and the magnetic leakage signal obtained through compensation calculation is the defect magnetic leakage signal under the given lift-off value.
According to the magnetic flux leakage detection lift-off compensation and defect depth analysis device provided by the embodiment of the invention, the probe device is simple in structure; the defect depth can be analyzed under the deviation and fluctuating lift-off values; the magnetic field signal under the high lift-off value can be converted to the magnetic field signal under the low lift-off value, so that the signal-to-noise ratio is enhanced; the lift-off effect can be compensated in real time, and the mechanical influences such as vibration and the like are reduced.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean 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.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (10)
1. A method for magnetic flux leakage detection lift-off compensation and defect depth analysis is characterized by comprising the following steps:
acquiring the height difference of the two triaxial magnetic field measurement chips in the normal direction;
acquiring magnetic field values of the two triaxial magnetic field measurement chips under current lift-off and height difference, wherein the magnetic field values comprise a first tangential component B of a first triaxial magnetic field measurement chipx(d1) And a first normal component By(d1) Second tangential component B of a second three-axis magnetic field measurement chipx(d2) And a second normal component By(d2)；
Carrying out magnetic field conversion variable on the magnetic field values of the two triaxial magnetic field measurement chips to obtain a first tangential component A of the magnetic field conversion variablex(d1) And a first normal component Ry(d1) Second tangential component Ax(d2) And a second normal component Ry(d2)；
According to the first tangential component Ax(d1) And said first normal component Ry(d1) Said second tangential component Ax(d2) And said second normal component Ry(d2) And calculating to obtain a first depth lift-off composite variable v (d)1) And a second depth lift-off complex variable v (d)2)；
Using the first depth to lift off a complex variable v (d)1) And said second depth lift-off complex variable v (d)2) And calculating the lift-off value d of the current first triaxial magnetic field measurement chip1The lift-off value d of the second triaxial magnetic field measurement chip2And the current defect depth h; and
and performing compensation calculation on the magnetic field value under the current defect depth condition by using the current defect depth h to obtain the magnetic field value under the target lift-off value.
2. The method for magnetic flux leakage detection lift-off compensation and defect depth analysis according to claim 1, wherein the height difference is determined at the design time of the probe device and is kept unchanged after the probe device is manufactured, and the relationship is satisfied at any time during the detection process:
r＝d2-d1
wherein r is height difference, thickness of the three-axis magnetic field measurement chip is more than or equal to d1For the lift-off value of the first three-axis magnetic field measuring chip, d2The lift-off value of the chip is measured for the second three-axis magnetic field.
3. The method of magnetic flux leakage detection lift-off compensation and defect depth resolution of claim 1, wherein the first tangential component Bx(d1) The first normal component By(d1) Said second tangential component Bx(d2) And said second normal component By(d2) The magnetic field values at the edges of the defects are all obtained, and the width of the defects is obtained through the peak width value of the leakage magnetic field waveform.
4. The method of leakage flux detection lift-off compensation and defect depth resolution of claim 1, wherein a tangential component a of the magnetic field transformation variablesx(y) and Ry(y) with the currently measured magnetic field Bx(y) and By(y) satisfies the following equation:
wherein A isx(y) comprises a first tangential component Ax(d1) And a second tangential component Ax(d2)，Ry(y) includes a first normal component Ry(d1) And a second normal component Ry(d2)，Bx(y) comprises a first tangential component Bx(d1) And a second tangential component Bx(d2)，By(y) denotes a first normal component By(d1) And a second normal component By(d2)，μ0Is the magnetic permeability in air, σsIs the equivalent linear magnetic charge density of the surface of the defect.
5. The method for flux leakage detection lift-off compensation and defect depth resolution of claim 1, wherein a depth lift-off complex variable v (y) and a magnetic field transformation variable Ax(y)，Ry(y) satisfies the relationship:
wherein v (y) includes a first depth lift-off complex variable v (d)1) And a second depth lift-off complex variable v (d)2)，Ax(y) comprises a first tangential component Ax(d1) And a second tangential component Ax(d2)，Ry(y) includes a first normal component Ry(d1) And a second normal component Ry(d2)。
6. The method for flux leakage detection lift-off compensation and defect depth resolution of claim 1, wherein the first depth lift-off complex variable v (d)1) And said second depthDegree lift-off complex variable v (d)2) A lift-off value d from the current first triaxial magnetic field measurement chip1And a lift-off value d of the second three-axis magnetic field measurement chip2Satisfies the relationship:
7. the method of leakage flux detection lift-off compensation and defect depth resolution of claim 1, wherein the current defect depth h is a complex variable of the first depth lift-off v (d)1) And said second depth lift-off complex variable v (d)2) Currently, the lift-off value d of the first triaxial magnetic field measurement chip1And a lift-off value d of the second three-axis magnetic field measurement chip2Satisfies the relationship:
8. the utility model provides a magnetic leakage detects and lifts away compensation and defect depth analytical equipment which characterized in that includes: two three-axis magnetic field measurement chips which are vertically distributed, a data processing unit and a data storage unit, wherein,
the two triaxial magnetic field measurement chips are positioned above the tested piece and used for acquiring the magnetic field value under the current probe inclination condition;
the data processing unit is respectively connected with the two triaxial magnetic field measurement chips and is used for analyzing and processing the magnetic field value under the current probe inclination condition to obtain a defect magnetic flux leakage signal under a correct posture;
the data storage unit is connected with the data processing unit and used for storing the data of the data processing unit.
9. The apparatus for magnetic flux leakage detection lift-off compensation and defect depth analysis according to claim 8, further comprising: pole shoes or steel brushes, permanent magnets, iron yokes;
the pole shoes or the steel brushes are positioned on two sides of the two triaxial magnetic field measurement chips, are symmetrically distributed and are used for restricting the magnetic field distribution between the magnetic flux leakage detector and the test piece;
the permanent magnets comprise a permanent magnet with a downward S pole and a permanent magnet with a downward N pole, are positioned above the pole shoe or the steel brush, are symmetrically distributed on two sides of the two triaxial magnetic field measurement chips and are used for magnetizing the tested piece;
and the iron yoke is positioned above the permanent magnet and the two triaxial magnetic field measurement chips and is used for constraining the magnetic field distribution inside the magnetic flux leakage detector and reducing a background magnetic field.
10. The magnetic flux leakage detection lift-off compensation and defect depth analysis device according to claim 8, wherein the data processing unit is specifically configured to:
carrying out magnetic field conversion variable on the magnetic field values of the two triaxial magnetic field measurement chips to obtain a first tangential component Ax(d1) And a first normal component Ry(d1) Second tangential component Ax(d2) And a second normal component Ry(d2)；
According to the first tangential component Ax(d1) And said first normal component Ry(d1) Said second tangential component Ax(d2) And said second normal component Ry(d2) And calculating to obtain a first depth lift-off composite variable v (d)1) And a second depth lift-off complex variable v (d)2)；
Using the first depth to lift off a complex variable v (d)1) And said second depth lift-off complex variable v (d)2) And calculating the lift-off value d of the current first triaxial magnetic field measurement chip1The lift-off value d of the second triaxial magnetic field measurement chip2And whenThe depth h of the front defect; and
and performing compensation calculation on the magnetic field value under the current defect depth condition by using the current defect depth h to obtain the magnetic field value under the target lift-off value.
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