Acoustic-ultrasonic pipeline defect detection device based on electromagnetic excitation

Abstract

The invention relates to the technical field of electromagnetic detection, in particular to an acoustic-ultrasonic pipeline defect detection device based on electromagnetic excitation. The acoustic-ultrasonic pipeline defect detection device based on electromagnetic excitation comprises a transducer, an acquisition system, an analysis module and an excitation system, wherein the transducer, the acquisition system and the analysis module are mounted on a detected pipeline; and the excitation system is mounted at the end part of the detected pipeline. The excitation system comprises an excitation coil and a permanent magnetic mechanism; the acquisition system collects echo signals through an acoustic emission sensor installed on a detected pipeline, the collected signals are processed through a pre-amplifier and then sent to a collector for conversion, and the converted signals are sent to an analysis module for data analysis. According to the acoustic-ultrasonic pipeline defect detection device based on electromagnetic excitation, a low-frequency signal with the frequency of 20-100 kHz is used as an excitation signal, so that high-frequency dispersion of a high-frequency excitation signal is avoided; the acoustic emission sensor and the pre-amplifier are used for receiving and processing guided wave signals, so that the detection precision is improved.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic detection technology, and in particular to an acoustic-ultrasonic pipeline defect detection device based on electromagnetic excitation. Background Technology

[0002] Electromagnetic acoustic-ultrasound (EAM) is a novel detection technology combining electromagnetic ultrasonic excitation and acoustic emission. This technology uses electromagnetic coupling to excite ultrasonic waves and acoustic emission sensors to receive them, combining these two techniques to solve many detection problems under special working conditions. It has attracted widespread attention due to its advantages such as high detection speed and consistent detection sensitivity for both internal and external surface defects. Acoustic-ultrasound stress waves propagating in solids exhibit minimal attenuation along their propagation path due to their inherent characteristics, thus overcoming the shortcomings of point-by-point scanning methods for long-distance, large-area defect detection. Furthermore, acoustic-ultrasound stress waves can propagate in liquid-filled and coated pipes, significantly reducing the cost of industrial pipeline inspection. Existing EAM detection methods typically use high-frequency excitation signals above 100kHz as the signal source, leading to high-frequency dispersion during operation. At low frequencies (20-100kHz), the signals are susceptible to noise interference, resulting in low measurement accuracy. Therefore, to address these shortcomings, an electromagnetically excited acoustic-ultrasound pipeline defect detection device is proposed. Summary of the Invention

[0003] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides an electromagnetically excited acoustic-ultrasonic pipeline defect detection device, which solves the problems of high-frequency dispersion caused by high-frequency excitation signals and low measurement accuracy under low-frequency excitation signals in electromagnetic acoustic-ultrasonic detection technology.

[0004] (II) Technical Solution To address the above problems, this invention provides an acoustic-ultrasonic pipeline defect detection device based on electromagnetic excitation, comprising: The system comprises a tested pipe, a transducer, a data acquisition system, and an analysis module. The transducer includes a signal generator, a power amplifier, and an excitation system mounted on the end of the tested pipe. The excitation system includes an excitation coil wound around the end of the tested pipe and multiple magnetizing units arranged in a circumferential array corresponding to the excitation coil. Each magnetizing unit is magnetic and forms a static magnetic field at the end of the tested pipe. The signal generator sends an excitation signal to the power amplifier, which amplifies the signal and transmits it to the excitation coil to form a dynamic magnetic field at the end of the tested pipe. The data acquisition system includes a preamplifier, a data acquisition unit, and multiple acoustic emission sensors. The acoustic emission sensors, mounted on the tested pipe, send the received signals to the preamplifier, which performs noise reduction processing on the received signals before sending them to the data acquisition unit. The data acquisition unit sends the received signals to the analysis module. The frequency of the excitation signal is 20-100 kHz.

[0005] Preferably, each magnetization unit includes a magnetic yoke arranged along the axial direction of the pipe being tested, and permanent magnets are respectively provided between the two ends of the magnetic yoke and the pipe being tested.

[0006] Preferably, three excitation coils are sequentially provided at the end of the pipe being tested.

[0007] Preferably, the excitation coil is composed of multiple parallel wires, with the current in adjacent wires flowing in opposite directions.

[0008] Preferably, the transducer is provided with a matching impedance.

[0009] Preferably, the power amplifier is equipped with a temperature protection module and a current overload protection module.

[0010] Preferably, the current overload protection module cuts off the current output when there is a current overload.

[0011] Preferably, the data acquisition module performs A / D conversion on the signal emitted by the preamplifier, converting the vibration signal into an electrical signal.

[0012] (III) Beneficial Effects The electromagnetically excited acoustic-ultrasonic pipeline defect detection device provided by this invention uses a low-frequency signal of 20-100kHz as the excitation signal, which avoids the problem of large dispersion of guided wave signals under high-frequency excitation signals; it uses an acoustic emission sensor to collect guided wave signals and processes the received guided wave signals through a preamplifier to improve the accuracy of acoustic-ultrasonic defect detection. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the electromagnetically excited acoustic-ultrasonic pipeline defect detection device of the present invention; Figure 2 This is a flowchart illustrating the working process of the electromagnetically excited acoustic-ultrasonic pipeline defect detection device of the present invention.

[0014] Among them, 1. permanent magnet; 2. magnetic yoke; 3. excitation coil; 4. acoustic emission sensor; 5. magnetization unit; 6. the pipe under test. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] In the description of this invention, it is necessary to understand that the orientation or positional relationship indicated by terms such as "upper", "lower", "inner", "outer", "top", and "bottom" are based on the orientation or positional relationship shown in the accompanying drawings. The purpose is only to facilitate the description of this invention and to simplify the description. It is not intended to indicate or imply that the component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0017] like Figure 1-2 As shown, this invention provides an electromagnetically excited acoustic-ultrasonic pipeline defect detection device, specifically including: a pipeline under test 6, a transducer, a data acquisition system, and an analysis module. The pipeline under test 6 is the object being measured, and the transducer and data acquisition system are installed on the pipeline under test 6. The transducer is installed at the end of the pipeline under test 6, forming a static magnetic field as a bias magnetic field and a dynamic magnetic field as an excitation magnetic field at the end of the pipeline under test 6. The static and dynamic magnetic fields are superimposed, causing the transducer to generate high-frequency vibration under mechanical force, forming an ultrasonic wave source. The ultrasonic wave propagates within the pipeline under test 6, transmitted as a guided wave. When the guided wave travels along the pipeline under test 6 and contacts the edge of a crack on the pipeline under test 6, the guided wave folds back to form an echo. The data acquisition system, installed on the pipeline under test 6, collects the echo signal of the ultrasonic wave transmitted within the pipeline under test 6 and sends the collected echo signal to the analysis module. The analysis module analyzes the received echo signal and the time of receipt of the echo signal to finally determine the location of the crack on the pipeline under test 6.

[0018] Before conducting the detection work, the range of various parameters of the echo signal collected by the acquisition system can be estimated according to the work plan. After the acquisition system collects the guided wave signal in the tested pipe 6, it preprocesses the guided wave signal and removes the echo signal whose parameters are outside the range of the parameters estimated before the work, thereby improving the accuracy of the device in detecting cracks in the tested pipe 6.

[0019] It should be noted that, in order to improve the accuracy of the detection, the acquisition system has multiple acquisition points on the pipe under test 6 to collect the echo signals inside the pipe under test 6. After the echo signals collected by each acquisition point are sent to the analysis module, the analysis module compares the guided wave signals received by each acquisition point to further improve the accuracy of the detection results.

[0020] In this invention, the transducer includes a signal generator, a power amplifier, and an excitation system. The excitation system is connected to the power amplifier, and the power amplifier is connected to the signal generator. The excitation system is installed at the end of the pipe under test 6, and forms a static magnetic field at the end of the pipe. The signal generator sends a pulse excitation signal to the power amplifier. The power amplifier amplifies the pulse excitation signal from the signal generator and sends it to the excitation system. The excitation system forms a dynamic magnetic field at the end of the pipe under test 6 that matches the parameters of the pulse signal based on the received pulse signal. After the dynamic magnetic field and the static magnetic field are superimposed, the transducer is subjected to mechanical force and generates high-frequency vibrations, releasing ultrasonic waves into the pipe under test 6.

[0021] The signal generator sends a low-frequency excitation signal with a pulse frequency between 20-100kHz. Due to its dispersion characteristics, multiple guided wave modes can be excited in a specific waveguide medium at the same frequency. The number of modes in the guided wave increases with frequency, resulting in significant dispersion in the guided wave formed by the superposition of the dynamic and static magnetic fields. When using a high-frequency excitation signal above 100kHz, the guided wave, during its propagation within the tested pipe 6, generates multiple guided wave modes due to continuous reflections on the inner wall of the pipe as the propagation distance increases. Excessive dispersion during signal collection leads to a smaller number of collected echo signals, reducing the accuracy of crack detection.

[0022] It should be noted that the transducer adopts the longitudinal guided wave excitation mode of L(2,0). Compared with the guided wave mode of L(1,0), the longitudinal guided wave excitation mode of L(2,0) is more sensitive to the detection of circumferential defects in the pipeline, which can improve the working efficiency of the device in detecting cracks in the pipeline under test.

[0023] like Figure 1As shown, the excitation system includes an excitation coil 4 wound around the end of the pipe 6 under test and multiple magnetization units 5 arranged in a circumferential array corresponding to the excitation coil 3. The magnetization units 5 are magnetic. After the multiple magnetization units 5 are arrayed, a static magnetic field is formed at the end of the pipe 6 under test. The excitation coil 4 is connected to a signal amplifier. The excitation signal emitted by the signal transmitter is amplified by the signal amplifier and then sent to the excitation coil 4. Current flows in the excitation coil 4, forming a dynamic magnetic field in the pipe 6 under test. The dynamic puncture is subjected to mechanical force under the action of the static magnetic field, thereby generating high-frequency vibration and forming an ultrasonic wave source.

[0024] Each magnetization unit 5 includes a magnetic yoke 2 arranged along the axial direction of the pipe 6 under test. Permanent magnets 1 are respectively provided between the two ends of the magnetic yoke 2 and the pipe 6 under test. The magnetization unit 5 uses the magnetic yoke 2 to magnetically connect the two permanent magnets 1 and arrange them in a circumferential array at the end of the pipe 6 under test. The magnetic interaction between the magnetization units 5 forms a stable static magnetic field.

[0025] It is important to note that three excitation coils 3 are sequentially arranged at the end of the pipe 6 under test. These excitation coils 3, combined with different bias magnetic fields, will generate different types of ultrasonic waves within the material or workpiece under test. These different ultrasonic waves are applied in different types of electromagnetic ultrasonic non-destructive testing. Each excitation coil 3 consists of multiple parallel wires, with the current in adjacent wires flowing in opposite directions. Because the current in adjacent wires flows in opposite directions, the resulting dynamic magnetic field also flows in opposite directions. When the position and winding direction of the three excitation coils 3 are adjusted, the strength of the generated magnetic field changes accordingly. The intensity of the dynamic magnetic field formed by the excitation coils 3 changes with the spacing between them. When the output frequency of the signal generator changes, appropriately adjusting the winding direction of the excitation coils 3 and the spacing between adjacent excitation coils 3 adjusts the direction and intensity of the dynamic magnetic field, ensuring that it always generates a longitudinal guided wave after being superimposed with the static magnetic field, thus improving the stability of the device.

[0026] The signal amplifier typically employs a high-voltage, high-current power amplifier with a maximum continuous output current of 8A and a peak current of 10A. In practical applications, the signal amplifier model can be changed according to operational needs to ensure accurate and selectable current limiting. Generally, the signal amplifier includes a load sensing module to monitor the current load in the circuit. It also incorporates an adjustment resistor; by adjusting the resistor's value, the current in the circuit is regulated, maintaining stable operation of the device.

[0027] The signal amplifier and power amplifier are equipped with a temperature protection module and a current overload protection module to ensure the safety of the device operation. When the operating temperature inside the device exceeds the preset maximum operating temperature, the temperature protection module activates and cuts off the circuit connection inside the device. The current overload protection module is used to prevent the current load inside the device from overloading. When the current load exceeds the preset load value, the current overload protection module disconnects the circuit connection inside the device for circuit protection. Under normal circumstances, the activation value of the overload protection is 105%-150% of the preset load. When the load value reaches the activation value, the current overload protection module activates and cuts off the circuit. When the load value is lower than 105% of the preset load, the current overload protection module restores the circuit connection, realizing automatic circuit disconnection and startup.

[0028] It should be noted that the difference between the impedance of the transducer and the output impedance of the power amplifier cannot exceed 10Ω. Therefore, a matching impedance is provided in the transducer. The matching impedance is generally set between the signal amplifier and the excitation coil 4. When the impedance of the transducer and the impedance of the power amplifier are mismatched, the matching impedance is connected to match the impedance between the two so that the interpolation does not exceed 10Ω.

[0029] In this invention, the acquisition system includes a preamplifier, a data acquisition unit, and multiple acoustic emission sensors 4. The acoustic emission sensors 4 are installed on the pipe 6 under test and transmit the received signals to the preamplifier. The preamplifier performs noise reduction processing on the received signals before sending them to the data acquisition unit. The acoustic emission sensors 4 are broadband piezoelectric sensors, sensitive to ultrasonic signals in the pipe 6 under test, which can increase the amount of signal collected, improve the reliability of the collected signal, and enhance the accuracy of the measurement results.

[0030] The preamplifier can filter the signal received by the acoustic emission sensor 4. Before the operation begins, it can estimate the range of various parameters of the effective guided wave received by the acoustic emission sensor 4 according to the pre-established work plan. By adjusting the preamplifier, guided wave signals outside the estimated range can be filtered out, improving the accuracy of the collected data. At the same time, the preamplifier can summarize all the received signals and filter out guided wave signals that have excessively large differences from other signal parameters and exist alone, thus removing erroneous signals in the data and further improving the accuracy of the measurement work.

[0031] It is important to note that after receiving the signal processed by the preamplifier, the acquisition unit performs an A / D conversion, converting the collected signal into a digital signal that can be directly input into the software, facilitating subsequent data summarization and analysis. The acquisition unit typically has 16-bit A / D conversion accuracy, and each information channel is equipped with four high-frequency filters and four low-frequency filters. These high-frequency and low-frequency filters can filter high-frequency and low-frequency guided wave signals respectively. By adjusting the switching states and operating sequence of the high-frequency and low-frequency filters, secondary filtering of the received signal can be performed. The filtering frequency of this secondary filtering is controlled by the working sequence and switching states of the high-frequency and low-frequency filters. In practice, before measurement, the arrangement of the high-frequency and low-frequency filters is adjusted to ensure that the filtering efficiency of the secondary filtering meets the operational requirements, improving detection efficiency and enhancing the defect identification rate under low-frequency excitation through signal processing.

[0032] In addition, the acquisition system is generally equipped with a control module consisting of an FPGA processor and an ASIC IC chip to perform data calculation and control other modules. The control module can adjust the working status of the high-frequency filter and the low-frequency filter in real time during operation, so as to achieve automatic adjustment of the secondary filtering frequency band and improve the practicality of the device.

[0033] The analysis module is connected to the acquisition system. After receiving the final parameters obtained by the acquisition system, it inputs the received signal into the analysis software for data analysis. The analysis module is generally a computer running in a Windows environment. When the analysis module receives the signal sent by the acquisition system, since the acquisition system has already performed A / D conversion on the signal, the analysis module can directly input the obtained signal into the existing calculation and analysis software for various data analysis.

[0034] The electromagnetically excited acoustic-ultrasonic pipeline defect detection device provided by this invention overcomes the high attenuation caused by high-frequency excitation, improves detection efficiency, and enhances the defect identification rate under low-frequency excitation through signal processing. The specific operation process of the device is as follows: Step 1: Based on the operating conditions, estimate the frequency of the echo and input the estimated range into the preamplifier. During operation, the preamplifier will discard data whose parameters fall outside the estimated range, improving data accuracy.

[0035] Step 2: Install the transducer at the end of the pipe being tested. At this point, the transducer will form a stable static magnetic field at the end of the pipe being tested.

[0036] Step 3: Connect the signal generator, power amplifier, and transducer. Place the sensing end of the acoustic emission sensor on the measuring point of the pipe under test and connect it to the preamplifier and the acquisition unit. Connect the acquisition unit to the analysis module.

[0037] Step 4: Start the signal generator and control it to emit an excitation signal of 20-100kHz. During this process, the excitation signal is amplified by the power amplifier and transmitted to the excitation coil of the transducer. The excitation signal flows within the ring-shaped excitation coil, generating a dynamic magnetic field with parameters matching the excitation signal. After the dynamic magnetic field is superimposed with the static magnetic field, the excitation coil is subjected to high-frequency vibration under the action of mechanical force, thus forming an ultrasonic source and sending ultrasonic waves into the pipe under test.

[0038] Step 5: Adjust the direction and spacing of the excitation coils to adjust the ultrasonic guided wave in the pipe under test to a longitudinal wave. During this process, when the direction and spacing of the excitation coils change, the direction and intensity of the dynamic magnetic field generated by the signal flow within the excitation coils also change. The mechanical force applied to the excitation coils after the superposition of the dynamic and static magnetic fields also changes. At this time, the mode of the guided wave generated by the transducer also changes. By adjusting the excitation coils so that the directions of the dynamic and static magnetic fields are parallel to the axial direction of the pipe under test, the guided wave output by the transducer is a longitudinal mode guided wave.

[0039] Step Six: The system collects and processes the echo signals from the tested pipe before sending them to the analysis module. During this process, the guided wave travels along the tested pipe. Upon contact with the boundary of a crack in the pipe, the guided wave bounces back, forming an echo. The acoustic emission sensor collects the guided wave signal from the tested pipe and sends the collected signal to the preamplifier. The preamplifier filters and discards the received signal according to pre-set parameter ranges, then amplifies the remaining signal and sends it to the collector. The collector performs an A / D conversion on the amplified signal, converting it into an electronic signal that can be directly input into the analysis software.

[0040] Step 7: The analysis module directly imports the received signals into the data analysis software for direct data analysis.

[0041] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A device for detecting acoustic-ultrasonic pipeline defects based on electromagnetic excitation, characterized in that, include: The test pipe (6), transducer, acquisition system and analysis module, the transducer includes a signal generator, a power amplifier and an excitation system installed at the end of the test pipe (6); the excitation system includes an excitation coil (3) wound around the end of the test pipe (6) and a plurality of magnetization units (5) arranged in a circumferential array corresponding to the excitation coil (3), the magnetization units (5) are magnetic and form a static magnetic field at the end of the test pipe (6); the signal generator sends an excitation signal to the power amplifier, the signal amplifier amplifies the excitation signal and transmits it to the excitation coil (3) to form a dynamic magnetic field at the end of the test pipe (6); the acquisition system includes a preamplifier, an acquisition unit and a plurality of acoustic emission sensors (4), the acoustic emission sensors (4) are installed on the test pipe (6) and send the received signal to the preamplifier, the preamplifier performs noise reduction processing on the received signal and sends it to the acquisition unit; The acquisition unit sends the received signal to the analysis module; the frequency of the excitation signal is 20-100kHz.

2. The acoustic-ultrasonic pipeline defect detection device based on electromagnetic excitation according to claim 1, characterized in that, Each magnetization unit (5) includes a magnetic yoke (2) arranged along the axial direction of the pipe (6) under test, and permanent magnets (1) are respectively provided between the two ends of the magnetic yoke (2) and the pipe (6) under test.

3. The acoustic-ultrasonic pipeline defect detection device based on electromagnetic excitation according to claim 1, characterized in that, The end of the pipe under test (6) is provided with three excitation coils (3) in sequence.

4. The acoustic-ultrasonic pipeline defect detection device based on electromagnetic excitation according to claim 3, characterized in that, The excitation coil (3) is composed of multiple wires arranged in parallel, with the current in adjacent wires in opposite directions.

5. The acoustic-ultrasonic pipeline defect detection device based on electromagnetic excitation according to claim 1, characterized in that, The transducer is equipped with a matching impedance.

6. The acoustic-ultrasonic pipeline defect detection device based on electromagnetic excitation according to claim 1, characterized in that, The power amplifier is equipped with a temperature protection module and a current overload protection module.

7. The acoustic-ultrasonic pipeline defect detection device based on electromagnetic excitation according to claim 6, characterized in that, The current overload protection module cuts off the current output when there is a current overload.

8. The acoustic-ultrasonic pipeline defect detection device based on electromagnetic excitation according to claim 1, characterized in that, The data acquisition module performs A / D conversion on the signal emitted by the preamplifier, converting the vibration signal into an electrical signal.

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