Defect detection pen type probe based on internal magnetic disturbance focusing sensing technology

Abstract

The invention discloses a defect detection pen-type probe based on an internal magnetic disturbance focusing sensing technology, which is characterized in that the pen-type probe is placed on a ferromagnetic test piece, a communication port of the probe is connected with an upper computer, and the probe is controlled to move to complete scanning detection on the tested piece; when the defect is scanned, the stable state of a magnetic field can be broken due to the fact that the magnetic resistance of the defect position is greatly different from that of the defect-free position, magnetic field disturbance can be generated above the defect, and magnetic field disturbance signals generated by the defect can be captured in the three-dimensional direction through the three-axis magnetic sensors which are densely arranged; the magnetic sensor converts a magnetic field signal into a digital signal and then transmits the digital signal to the upper computer through the data acquisition and transmission system, and a three-axis imaging picture of the defect is finally obtained after the signal is processed by the data processing terminal.

Description

Technical Field

[0001] The invention belongs to the technical field of electromagnetic nondestructive testing, and more specifically, relates to a defect detection pen-type probe based on internal magnetic disturbance focusing sensing technology. Background Art

[0002] Oil and gas pipelines are important carriers of national energy transmission. To ensure the normal operation of pipelines, safe maintenance and regular inspections are very important. Electromagnetic nondestructive testing technology is an important branch of nondestructive testing. It uses the changes in the electrical or magnetic properties of the tested material under the action of the electromagnetic field, and uses the detection unit to capture electromagnetic information to detect and effectively evaluate structural damage such as defects, fatigue, residual stress, etc. of the tested material.

[0003] At present, the electromagnetic technologies used in pipeline inspection mainly include leakage magnetic detection, eddy current detection, AC electromagnetic field detection, magnetic particle detection and other detection methods. Due to the long-term oil and gas transportation of pipelines, the types of defects in pipeline structures vary, mainly including structural damage such as corrosion, pits, cracks and scratches. The single in-pipeline detection method has limited ability to evaluate the safety of pipeline structures. The integration of multiple detection methods can achieve a comprehensive assessment of pipelines to a certain extent. Among them, the principle of leakage magnetic detection is to use two permanent magnets as two-pole magnetization devices. The two permanent magnets are connected by high magnetic permeability materials. Both permanent magnets transmit magnetic lines of force to the ferromagnetic pipeline through pole shoes. After the ferromagnetic pipeline is magnetized, an induced magnetic field can be generated in the pipeline. If there are volume defects such as corrosion and mechanical damage on the pipeline, the magnetic lines of force will leak to the outside of the plate, thereby forming a leakage magnetic field on its surface. Defects parallel to the magnetization direction cannot leak magnetic fields. Therefore, this method cannot detect defects parallel to the magnetization direction, and is only suitable for structural health assessment of ferromagnetic materials.

[0004] However, as ferromagnetic materials are widely used in aerospace, pipeline transportation and other industrial fields, magnetic disturbance detection technology is based on the change of magnetic properties of ferromagnetic materials, and can capture defect signals with high sensitivity. It is especially suitable for surface defect detection of complex geometric structures, and has the characteristics of no need for pretreatment and economic efficiency. Traditional magnetic disturbance technology generally places the magnetic sensor directly under the permanent magnet, which will cause the probe to have a large adsorption force, inconvenient movement, easy damage to the magnetic sensor under pressure, can only obtain single-axis magnetic signals, and low resolution. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a defect detection pen probe based on internal magnetic perturbation focusing sensing technology. By designing a new magnetic focusing sensing structure and configuring a high-resolution three-axis magnetic sensor array, high-sensitivity detection of surface defects of ferromagnetic materials and high-resolution three-dimensional magnetic imaging can be achieved, and the probe has a low adsorption force and is easy to detect.

[0006] To achieve the above-mentioned purpose of the invention, the present invention is a defect detection pen-type probe based on internal magnetic disturbance focusing sensing technology, characterized in that it includes: a focusing internal magnetic disturbance probe, a mechanical structure, a data acquisition and transmission system and a data processing terminal;

[0007] The focused internal magnetic disturbance probe is used to scan the test piece, capture the magnetic field disturbance signal generated by the defect, and then convert the magnetic field disturbance signal into a digital signal, and then convert the digital signal into serial port data through a USB to TTL module, and upload it to the data processing terminal;

[0008] The mechanical structure is used to encapsulate the focused internal magnetic disturbance probe, data acquisition and transmission system, and is shaped like a pen;

[0009] The data acquisition and transmission system is used to send instructions to the three-axis magnetic sensor array, read the digital signals returned by the three-axis magnetic sensors and upload them to the data processing terminal;

[0010] The data processing terminal is used to store and analyze the digital signals uploaded by the data acquisition and transmission system, draw the original waveform diagrams of each axis of the three-axis magnetic sensor array and the three-axis imaging diagram, and finally obtain the location and size information of the defect.

[0011] The object of the invention of the present invention is achieved in this way:

[0012] The present invention is based on a defect detection pen probe of internal magnetic disturbance focusing sensing technology. The pen probe is placed on a ferromagnetic test piece, and the probe communication port is connected to a host computer to control the movement of the probe to complete scanning and detection of the test piece. Specifically, when the pen probe scans the test piece, the magnetic field lines generated by the permanent magnet will produce a magnetic field gathering effect when passing through the pen-shaped high magnetic permeability silicon steel magnetic concentrating structure. The magnetic field distribution is the strongest near the two ends of the bottom groove. When the magnetic field lines propagate to the junction of the silicon steel and the air near the two ends of the thin groove at the bottom of the silicon steel, due to the difference in magnetic permeability between the silicon steel and the air and the boundary conditions of magnetic field propagation, the magnetic field lines enter the air perpendicular to the interface, and then the left and right magnetic lines Due to the change of magnetic resistance, the lines will be superimposed at the magnetic sensor, generating a magnetic field in a downward direction; when no defects are detected, the magnetic field distribution at the sensor is in a stable state, and there will be no signal fluctuations; when defects are detected, due to the large difference in magnetic resistance between the defect and the non-defective area, the stable state of the magnetic field will be broken, and magnetic field disturbances will be generated above the defects. The densely arranged three-axis magnetic sensors can capture the magnetic field disturbance signals generated by the defects in the three-dimensional direction; the magnetic sensor converts the magnetic field signal into a digital signal and then transmits the signal to the host computer through the data acquisition and transmission system. After processing by the data processing terminal, the three-axis imaging diagram of the defect is finally obtained.

[0013] At the same time, the defect detection pen probe based on the internal magnetic disturbance focusing sensing technology of the present invention also has the following features:

[0014] Beneficial effects:

[0015] (1) The present invention designs a pen-shaped high magnetic permeability silicon steel magnetic concentrator sensor structure, which can have a concentrating effect on the magnetic field distribution. When the probe has a low adsorption force on the test piece (low magnetization), the detection sensitivity of the internal magnetic disturbance probe can be enhanced without affecting the linear range of the magnetic sensor signal. In addition, the fine groove area at the bottom of the structure is embedded with a magnetic sensor, which protects the magnetic sensor to a certain extent.

[0016] (2) The present invention designs a densely arranged three-axis magnetic sensor array, which has a total of 15 three-axis magnetic sensors and an arrangement spacing of 1 mm, which can achieve spatial high-resolution three-axis magnetic imaging of defects.

[0017] (3) The present invention uses permanent magnets for static magnetic field excitation, and the signal excitation part does not need to be powered, thus meeting the low power consumption requirement. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a specific implementation scheme of the defect detection pen-type probe based on the internal magnetic disturbance focusing sensing technology of the present invention;

[0019] Figure 2 It is a schematic diagram of the detection principle of the defect detection pen-type probe based on the internal magnetic disturbance focusing sensing technology of the present invention;

[0020] FIG3 is a schematic diagram of a test piece;

[0021] Figure 4 This is the test result diagram of the dense hole defect specimen;

[0022] Figure 5 This is the test result diagram of the specimen with a slot parallel to the scanning direction;

[0023] Figure 6 This is the test result diagram of the specimen with a groove perpendicular to the scanning direction. DETAILED DESCRIPTION

[0024] The specific implementation of the present invention is described below in conjunction with the accompanying drawings so that those skilled in the art can better understand the present invention. It should be noted that in the following description, when the detailed description of known functions and designs may dilute the main content of the present invention, these descriptions will be omitted here.

[0025] Example

[0026] In this embodiment, if Figure 1As shown, the present invention is a defect detection pen-type probe based on internal magnetic disturbance focusing sensing technology, comprising: a focusing internal magnetic disturbance probe, a mechanical structure, a data acquisition and transmission system and a data processing terminal;

[0027] The focused internal magnetic disturbance probe is used to scan the test piece, capture the magnetic field disturbance signal generated by the defect, and then convert the magnetic field disturbance signal into a digital signal, and then convert the digital signal into serial port data through the USB to TTL module, and upload it to the data processing terminal;

[0028] In this embodiment, the focused internal magnetic disturbance probe includes a cylindrical permanent magnet, the lower part of which has a pen-shaped high magnetic permeability silicon steel with a magnetic field sensing function, a fine groove inside the silicon steel structure, and a single-row three-axis magnetic sensor array structure is placed at the bottom of the fine groove;

[0029] The three-axis magnetic sensor array contains 15 digital three-axis Hall magnetic sensors, and the magnetic sensors are spaced 1mm apart.

[0030] The mechanical structure is used to encapsulate the focused internal magnetic disturbance probe, data acquisition and transmission system, and is shaped like a pen;

[0031] In this embodiment, the mechanical structure is composed of polyfiber material and a spring, wherein a rectangular cavity area is provided inside the mechanical structure for storing the main control board of the data acquisition and transmission system; a fixed aviation plug is provided at the top of the mechanical structure for plugging in a shielded cable and then transmitting the acquisition signal of the three-axis Hall magnetic sensor; the spring is embedded in the interior of the mechanical structure and is located between the main control board of the data acquisition and transmission system and the focused internal magnetic disturbance probe to realize the telescopic adjustment of the focused internal magnetic disturbance probe.

[0032] The data acquisition and transmission system is used to send instructions to the three-axis magnetic sensor array, read the digital signals returned by the magnetic sensors and upload them to the data processing terminal;

[0033] The data processing terminal is used to save and analyze the digital signals uploaded by the data acquisition and transmission system, draw the original waveform diagram of each axis of the three-axis magnetic sensor array and the three-axis imaging diagram, and finally obtain the location and size information of the defect.

[0034] like Figure 2As shown in the figure, when the pen-type probe scans the test piece, the magnetic lines of force generated by the permanent magnet will produce a gathering effect when passing through the pen-shaped high magnetic permeability silicon steel focusing sensor. The magnetic field distribution is most dense near the two ends of the bottom slot. When the magnetic lines of force propagate to the junction of the silicon steel and the air near the two ends of the bottom slot, due to the difference in magnetic permeability between the silicon steel and the air and the boundary conditions of magnetic field propagation, the magnetic lines of force enter the air perpendicular to the interface, and then the left and right magnetic lines of force will be superimposed at the magnetic sensor due to the change in magnetic resistance, generating a downward magnetic field. When no defects are detected, the magnetic field in the silicon steel fine slot area is in a stable state, and no signal fluctuations will occur. When defects are detected, due to the large difference in magnetic resistance between the defect and the non-defective area, the stable state of the magnetic field will be broken, and magnetic field disturbances will be generated above the defect. The three-axis magnetic sensor is used to capture the magnetic field disturbance signal generated by the defect; then the three-axis magnetic sensor converts the magnetic field signal into a digital signal and then transmits the signal to the host computer through the data acquisition and transmission system. After being processed by the data processing terminal, the three-axis imaging diagram of the defect is finally obtained.

[0035] FIG3 is a schematic diagram of a test piece;

[0036] In this embodiment, as shown in FIG3 , the three tested pieces are all ferromagnetic test pieces, among which FIG3 (a) is a dense hole defect test piece, the diameter of the hole is 1 mm, and the scanning direction of the probe and the direction of the spatial coordinate axis are shown in the figure; FIG3 (b) is a groove test piece parallel to the scanning direction, the size of the groove is: x: 20 mm y: 3 mm z: 2 mm, and the scanning direction of the probe and the direction of the spatial coordinate axis are shown in the figure. FIG3 (c) is a groove test piece perpendicular to the scanning direction, the size of the groove is: x: 0.4 mm y: 8 mm z: 8 mm, and the scanning direction of the probe and the direction of the spatial coordinate axis are shown in the figure.

[0037] Figure 4 This is the test result diagram of the dense hole defect specimen;

[0038] like Figure 4 As shown in the figure, the x-axis, y-axis, and z-axis imaging results can well distinguish the signals of each dense small hole, and can well show the spatial distribution of each dense small hole. Figure 4 It can be seen that: the white part in the x-axis image is the peak position, the dark gray part is the trough position, and the distance between the peak and the trough contains the size information of the defect in the x-axis direction; similarly, the white part in the y-axis image is the peak position, the dark gray part is the trough position, and the distance between the peak and the trough contains the size information of the defect in the y-axis direction; the z-axis image shows that the signal has only one peak, which is a single-peak signal.

[0039] Figure 5 This is the test result diagram of the specimen with a slot parallel to the scanning direction;

[0040] like Figure 5As shown in the figure, the white part in the x-axis image is the peak position, the black part is the trough position, and the distance between the peak and the trough contains the size information of the defect in the x-axis direction; the white part in the y-axis image is the peak position, the black part is the trough position, and the distance between the peak and the trough contains the size information of the defect in the y-axis direction; the z-axis signal can clearly show the morphology of the defect.

[0041] Figure 6 This is the test result diagram of the specimen with a slot perpendicular to the scanning direction;

[0042] like Figure 6 As shown in the figure, the white part in the x-axis image is the peak position, the black part is the trough position, and the distance between the peak and the trough contains the size information of the defect in the x-axis direction; the white part in the y-axis image is the peak position, the black part is the trough position, and the distance between the peak and the trough contains the size information of the defect in the y-axis direction; the z-axis signal can clearly show the morphology of the defect.

[0043] Although the above describes the illustrative specific embodiments of the present invention to facilitate those skilled in the art to understand the present invention, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations using the concept of the present invention are protected.

Claims

1. A defect detection pen probe based on internal magnetic disturbance focusing sensing technology, characterized in that: include: Focus on the internal magnetic disturbance probe, mechanical structure, data acquisition and transmission system and data processing terminal; The focused internal magnetic disturbance probe is used to scan the test piece, capture the magnetic field disturbance signal generated by the defect, and then convert the magnetic field disturbance signal into a digital signal, and then convert the digital signal into serial port data through a USB to TTL module, and upload it to the data processing terminal; The mechanical structure is used to encapsulate the focused internal magnetic disturbance probe, data acquisition and transmission system, and is shaped like a pen; The data acquisition and transmission system is used to send instructions to the three-axis magnetic sensor array, read the digital signals returned by the three-axis magnetic sensors and upload them to the data processing terminal; The data processing terminal is used to store and analyze the digital signals uploaded by the data acquisition and transmission system, draw the original waveform diagrams of each axis of the three-axis magnetic sensor array and the three-axis imaging diagram, and finally obtain the location and size information of the defect.

2. The defect detection pen probe based on internal magnetic disturbance focusing sensing technology according to claim 1 is characterized in that: The focused internal magnetic disturbance probe includes a cylindrical permanent magnet, a pen-shaped high magnetic permeability silicon steel with a magnetic field sensing function at the bottom of the permanent magnet, a fine groove inside the silicon steel structure, and a single-row three-axis magnetic sensor array is placed at the bottom of the fine groove.

3. The defect detection pen probe based on internal magnetic disturbance focusing sensing technology according to claim 1 is characterized in that: The three-axis magnetic sensor array includes 15 digital three-axis Hall magnetic sensors, and the magnetic sensors are spaced 1 mm apart.

4. The defect detection pen probe based on internal magnetic disturbance focusing sensing technology according to claim 1 is characterized in that: The mechanical structure is composed of polyfiber material and springs.

5. The defect detection pen probe based on internal magnetic disturbance focusing sensing technology according to claim 4 is characterized in that: A rectangular cavity area is provided inside the mechanical structure for storing a main control board of a data acquisition and transmission system.

6. The defect detection pen probe based on internal magnetic disturbance focusing sensing technology according to claim 4 is characterized in that: A fixed aviation plug is arranged at the top of the mechanical structure for plugging in a shielded cable and then transmitting the acquisition signal of the three-axis Hall magnetic sensor.

7. The defect detection pen probe based on internal magnetic disturbance focusing sensing technology according to claim 4 is characterized in that: The spring is embedded in the mechanical structure and is located between the main control board of the data acquisition and transmission system and the focused internal magnetic disturbance probe to achieve telescopic adjustment of the focused internal magnetic disturbance probe.

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