A magnetically concentrated electromagnetic ultrasonic guided wave transducer

Abstract

The application relates to a magnetic concentration type electromagnetic ultrasonic guided wave transducer which detects a detected piece by arranging a wedge-shaped magnet and a high-frequency coil on the detected piece and does not arrange a coupling medium, is simple in structure, small in size, can provide a more concentrated magnetic field, and improves guided wave excitation efficiency relative to a traditional electromagnetic ultrasonic guided wave transducer.

Description

Technical Field

[0001] This invention relates to a magnetically concentrated electromagnetic ultrasonic guided wave transducer, belonging to the field of electromagnetic ultrasonic guided wave transducers. Background Technology

[0002] Since the 1970s, electromagnetic ultrasound has gradually entered the stage of non-destructive testing (NDT). After half a century of development, it has become one of the most watched NDT methods. An electromagnetic ultrasonic transducer typically consists of three parts: a magnet, a high-frequency coil, and the test piece. The magnet primarily provides the bias magnetic field, while the high-frequency coil excites ultrasonic waves on the surface of the test piece. The test piece is an indispensable part of the electromagnetic ultrasonic transducer; it must possess at least one of the properties of electrical conductivity and magnetic permeability. This is why electromagnetic ultrasonic transducers differ from traditional ultrasonic transducers, which require coupling agents. Ultrasonic guided wave-based testing methods have also attracted attention due to their speed and efficiency.

[0003] Ultrasonic testing technology is a non-destructive testing method with the following advantages: it can be used for non-destructive defect detection of both metallic and non-metallic materials; ultrasound does not affect the test piece; it does not require close contact with the test piece, making it suitable for testing complex-shaped specimens; it is harmless to humans and the environment; and the equipment is lightweight, allowing for on-site testing. Based on these advantages, ultrasonic testing technology has been widely used in thickness measurement, high-temperature testing, and in-service inspection of long-distance pipelines. Ultrasonic testing includes piezoelectric ultrasonic testing and electromagnetic ultrasonic testing. However, piezoelectric ultrasonic testing relies on a coupling agent, which complicates the testing process, limits speed, reduces efficiency, and increases difficulty. Therefore, the use of coupling agents severely restricts the safe application of long-distance oil and gas pipelines. Electromagnetic ultrasonic non-destructive testing technology has been developing for over a century and is currently widely used for defect detection.

[0004] Electromagnetic ultrasonic guided wave transducers rely on electromagnetic effects to directly excite ultrasonic waves onto the test piece. The specific electromagnetic-to-force conversion mechanisms typically include the Lorentz force mechanism and the magnetostrictive effect mechanism. In conductive non-ferromagnetic materials, only the Lorentz force exists; in ferromagnetic materials, both effects are usually present, with the magnetostrictive effect being dominant. Electromagnetic ultrasonic guided wave transducers generally consist of a permanent magnet, a high-frequency coil, and the test piece. They typically offer the significant advantages of being non-contact and requiring no coupling. Traditional electromagnetic ultrasonic guided wave transducers mostly use bar magnets or horseshoe magnets, which are relatively bulky in practical non-destructive testing applications and require increasing the magnet volume to enhance the transduction effect and increase the guided wave amplitude. This, however, leads to an increase in the size of the electromagnetic ultrasonic transducer. Summary of the Invention

[0005] The purpose of this invention is to provide a magnetically concentrated electromagnetic ultrasonic guided wave transducer that does not require a coupling medium, is compact in size, and can improve the amplitude of guided waves.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a magnetically concentrated electromagnetic ultrasonic guided wave transducer, disposed on the device to be tested, comprising:

[0007] A high-frequency coil is placed on the device to be tested.

[0008] Two wedge-shaped magnets are disposed on the test piece and located on both sides of the high-frequency coil, with the magnetic poles of the two wedge-shaped magnets opposite to those on the side of the test piece.

[0009] In this embodiment, at least a portion of the cross-sectional area of ​​the wedge magnet decreases in the direction away from the high-frequency coil, and a triangular gap is formed between it and the object to be tested.

[0010] Furthermore, the wedge magnet includes a first segment close to the high-frequency coil and a second segment connected to the first segment, wherein the cross-sectional area of ​​the second segment decreases in the direction away from the high-frequency coil, or the cross-sectional areas of the first segment and the second segment decrease in the direction away from the high-frequency coil.

[0011] Furthermore, the component to be tested is a metal pipe.

[0012] Furthermore, the wedge-shaped magnet is sleeved on the metal pipe, the cross-section of the wedge-shaped magnet is a right trapezoid, and the short side of the right trapezoid is sleeved with the component to be tested.

[0013] Furthermore, the high-frequency coil is a copper foil coil.

[0014] Furthermore, the copper foil coil has 6 turns.

[0015] Furthermore, the distance between the wedge magnet and the high-frequency coil is 0-40mm.

[0016] Furthermore, the thickness of the wedge magnet is 5-25mm, and the width of the wedge magnet is 2-10mm.

[0017] The beneficial effects of this invention are as follows: This application achieves the detection of the test piece by setting a wedge magnet and a high-frequency coil on the test piece, without the need for a coupling medium. Compared with traditional electromagnetic ultrasonic guided wave transducers, it has a simple structure, small size, can provide a more focused magnetic field, and improves the guided wave excitation efficiency.

[0018] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a magnetically concentrated electromagnetic ultrasonic waveguide transducer according to a preferred embodiment of this application;

[0020] Figure 2 This is a simulation diagram of a square magnet.

[0021] Figure 3 for Figure 2 Simulation experiment data graph;

[0022] Figure 4 A simulation diagram of a wedge magnet with a longer upper base in a right-angled trapezoidal cross-section;

[0023] Figure 5 for Figure 4 Simulation experiment data graph;

[0024] Figure 6 A simulation diagram of a wedge magnet 30 with a shorter upper base side in a right-angled trapezoidal cross-section;

[0025] Figure 7 for Figure 6 Simulation experiment data graph;

[0026] Figure 8 The graph shows experimental data on the spacing between the wedge magnet and the high-frequency coil.

[0027] Figure 9 for Figure 8 The experimental data is presented in a bar chart. Detailed Implementation

[0028] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0029] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0030] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0031] Please refer to Figure 1 A preferred embodiment of this application shows a magnetically concentrated electromagnetic ultrasonic guided wave transducer, which is disposed on the test piece 10. The magnetically concentrated electromagnetic ultrasonic guided wave transducer includes a high-frequency coil 20 and two wedge magnets 30. The high-frequency coil 20 is disposed on the test piece 10.

[0032] Two wedge magnets 30 are disposed on the test piece 10 and located on both sides of the high-frequency coil 20, with the magnetic poles of the two wedge magnets 30 opposite to those on the test piece 10.

[0033] Among them, at least a portion of the wedge magnet 30 has a decreasing cross-sectional area in the direction away from the high-frequency coil 20, and forms a triangular gap with the test piece 10.

[0034] Simulation experiments were conducted using a square magnet with a width of 8.8 mm and a height of 5 mm, a wedge magnet with a right-angled trapezoidal cross-section having an upper base of 4.4 mm, a lower base of 8.8 mm, and a height of 5 mm, and a wedge magnet with a right-angled trapezoidal cross-section having an upper base of 2.2 mm, a lower base of 8.8 mm, and a height of 5 mm. Please refer to [reference needed]. Figure 2 and Figure 3 Therefore, the amplitude of the received signal from a square magnet with a width of 8.8 mm and a height of 5 mm is approximately 7.3 × 10⁻⁶. -7 Reference photo Figure 4 and Figure 5 Simulation data of a wedge magnet with a right-angled trapezoidal cross-section, an upper base of 4.4 mm, a lower base of 8.8 mm, and a height of 5 mm, shows that the amplitude of its received signal is approximately 9.15 × 10⁻⁶ mm. -7 Reference photo Figure 6 and Figure 7 Simulation data of a wedge magnet with a right-angled trapezoidal cross-section, an upper base of 2.2 mm, a lower base of 8.8 mm, and a height of 5 mm, shows that the amplitude of the received signal is approximately 10.1 × 10⁻⁶. -7 Through this simulation experiment, it can be found that wedge magnets can excite guided waves with higher amplitudes than square magnets, and the amplitude of guided waves can be increased by appropriately reducing the length of the upper base of the right-angled trapezoid.

[0035] Electromagnetic ultrasonic guided wave transducers mainly employ two transduction mechanisms: Lorentz force and magnetostrictive force, as follows:

[0036] In the operation of an electromagnetic ultrasonic guided wave transducer based on the Lorentz force mechanism, the high-frequency current J flowing through the high-frequency coil 20 generates an alternating magnetic field around the transducer with the same frequency as the transmitting current. This, in turn, induces eddy currents J in the conductor surface skin depth with the same frequency and opposite direction to the coil current. e ,like Figure 1 As shown, the magnet generates a bias static magnetic field B. s Alternating induced eddy currents generate a Lorentz force F under the influence of a magnetic field. L The direction of the force is determined by the left-hand rule. Under the action of the Lorentz force, the specimen produces periodic vibrations. When this vibration propagates along the specimen in the form of a wave, the electromagnetic ultrasonic wave transmission process is completed. During the reception process of the electromagnetic ultrasonic guided wave transducer, when the ultrasonic wave travels below the transducer, the particle vibration will cut the static magnetic field generated in the electromagnetic ultrasonic guided wave transducer, inducing an electromotive force and an induced current in the specimen, and then generating an induced magnetic field near the transducer; when the receiving coil is in a changing magnetic field, a voltage will be induced in the coil. By detecting and analyzing this voltage, the information carried by the ultrasonic wave propagating from the excitation point can be obtained.

[0037] Magnetostrictive electromagnetic ultrasonic waveguide transducers utilize the magnetostrictive effect of materials and its inverse effect to excite and receive ultrasonic waves. A high-frequency current J is passed through the high-frequency coil 20, which generates an alternating magnetic field B in the ferromagnetic specimen with the same frequency as the transmitting current. d The magnet in the electromagnetic ultrasonic guided wave transducer provides the bias magnetic field B. s Ferromagnetic materials, under the influence of dynamic and static magnetic fields, undergo periodic deformation due to the magnetostriction effect, resulting in internal vibrations that ultimately propagate outward as ultrasonic waves. During the reception process of an electromagnetic ultrasonic guided wave transducer, when the guided wave propagates below the transducer, it causes structural deformation. According to the inverse magnetostriction effect, the magnetic field within the ferromagnetic material changes, subsequently altering the magnetic field near the transducer. When the receiving coil is in this changing magnetic field, a voltage is induced within the coil. Analyzing this voltage reveals the information contained in the received signal.

[0038] In this embodiment, the wedge magnet 30 includes a first segment near the high-frequency coil 20 and a second segment connected to the first segment. The cross-sectional areas of the first and second segments decrease in the direction away from the high-frequency coil 20, and the end face of the first end abuts against the surface of the test piece 10, improving the stability of the wedge magnet 30 installation. Of course, the cross-sectional area of ​​the second segment can also decrease in the direction away from the high-frequency coil 20.

[0039] The test piece 10 is a metal pipe, and a wedge magnet 30 is mounted on the metal pipe. The cross-section of the wedge magnet 30 is a right trapezoid, and the short side of the right trapezoid is connected to the test piece 10.

[0040] The high-frequency coil 20 is a copper foil coil with 6 turns. The distance between the wedge magnet 30 and the high-frequency coil 20 is 0-40mm. By changing the distance between the wedge magnet 30 and the high-frequency coil 20, the received amplitude at different distances between the magnet and the coil is studied to determine the effect of the distance between the magnet and the coil on the transduction efficiency. In this verification, verification was performed at distances of 0mm, 20mm, 40mm, 60mm, and 80mm, respectively, with reference to... Figure 8 and Figure 9 It can be seen that the amplitude of the received signal increases first and then decreases slowly as the distance between the magnet and the coil increases. Therefore, the optimal distance between the wedge magnet 30 and the high-frequency coil 20 is 0-40mm, and the optimal distance value is 20mm. At this time, the amplitude of the received signal of the magnetically concentrated electromagnetic ultrasonic waveguide transducer is at its peak, which can improve the monitoring accuracy and transduction efficiency.

[0041] The wedge magnet 30 has a thickness of 5-25 mm and a width of 2-10 mm. Preferably, when the wedge magnet 30 has a width of 8.8 mm and a thickness of 25 mm, the amplitude of the received signal is at its maximum value, approximately 16.8 × 10⁻⁶. -7 At this time, the amplitude of the received signal from the magnetically concentrated electromagnetic ultrasonic guided wave transducer is at its peak, which improves monitoring accuracy and transduction efficiency.

[0042] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0043] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A magnetically concentrated electromagnetic ultrasonic guided wave transducer, mounted on the workpiece to be tested, characterized in that, include: A high-frequency coil is placed on the device to be tested. Two wedge-shaped magnets are disposed on the test piece and located on both sides of the high-frequency coil, with the magnetic poles of the two wedge-shaped magnets opposite to those on the side of the test piece. In this embodiment, at least a portion of the cross-sectional area of ​​the wedge magnet decreases in the direction away from the high-frequency coil, and a triangular gap is formed between it and the object to be tested.

2. The magnetically concentrated electromagnetic ultrasonic guided wave transducer as described in claim 1, characterized in that, The wedge magnet includes a first segment near the high-frequency coil and a second segment connected to the first segment, wherein the cross-sectional area of ​​the second segment decreases in the direction away from the high-frequency coil, or the cross-sectional areas of the first segment and the second segment decrease in the direction away from the high-frequency coil.

3. The magnetically concentrated electromagnetic ultrasonic guided wave transducer as described in claim 1, characterized in that, The component to be tested is a metal pipe.

4. The magnetically concentrated electromagnetic ultrasonic guided wave transducer as described in claim 3, characterized in that, The wedge-shaped magnet is sleeved on the metal pipe, and the cross-section of the wedge-shaped magnet is a right trapezoid, with the short side of the right trapezoid connected to the part to be tested.

5. The magnetically concentrated electromagnetic ultrasonic guided wave transducer as described in claim 1, characterized in that, The high-frequency coil is a copper foil coil.

6. The magnetically concentrated electromagnetic ultrasonic guided wave transducer as described in claim 5, characterized in that, The copper foil coil has 6 turns.

7. The magnetically concentrated electromagnetic ultrasonic guided wave transducer as described in claim 1, characterized in that, The distance between the wedge magnet and the high-frequency coil is 0-40mm.

8. The magnetically concentrated electromagnetic ultrasonic guided wave transducer as described in claim 5, characterized in that, The thickness of the wedge magnet is 5-25mm, and the width of the wedge magnet is 2-10mm.

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