Composite probe for electromagnetic ultrasound and eddy current and its working method

Abstract

The present invention discloses a composite electromagnetic ultrasonic and eddy current probe and its operating method. The probe comprises: a housing containing a magnet; an electromagnetic ultrasonic coil disposed directly below the magnet, with an electromagnetic ultrasonic shielding layer disposed between the electromagnetic ultrasonic coil and the magnet; an eddy current coil wound around the outside of the eddy current shielding layer within the housing, with its bottom end flush with the electromagnetic ultrasonic coil and adjacent to a ceramic sheet; and the magnet located inside the eddy current shielding layer. Both the eddy current coil leads and the electromagnetic ultrasonic coil leads are led out through reserved spaces in the housing and the eddy current shielding layer to facilitate connector connection. The composite electromagnetic ultrasonic and eddy current probe overcomes the shortcomings of eddy current probes being insensitive to the interior of materials and electromagnetic ultrasonic testing being insensitive to the surface of materials. It can also separate mutually coupled and interfering eddy current signals and electromagnetic ultrasonic signals, improving detection efficiency and accuracy.

Description

Technical Field

[0001] The present invention relates to the field of non-destructive testing, in particular to an electromagnetic ultrasound and eddy current composite probe and a working method thereof. Background Art

[0002] Traditional ultrasonic testing mostly uses piezoelectric transducers. The disadvantage is that before each test, the surface of the test piece should be polished and then coated with coupling agent. This process limits the continuity of the test, thereby reducing the efficiency of the test. Electromagnetic ultrasonic probes are non-contact and insensitive to the surface structure of the test piece, so they can perform rapid and continuous detection of the target. Electromagnetic ultrasound uses the principle of electromagnetic induction. A high-frequency alternating current is passed through the coil to induce a corresponding induced current in the test piece. Under the action of a strong magnet, the particles in the test piece are affected by the Lorentz force, thereby generating ultrasonic elastic waves. When the ultrasonic elastic wave encounters a defect or a sudden change in the material boundary, it will be reflected. The reflected wave propagates to the probe, converting the mechanical signal into an electrical signal, thereby realizing the detection of the internal situation of the test piece.

[0003] When it comes to detecting surface defects, eddy current testing offers superior sensitivity compared to common nondestructive testing methods such as magnetic particle testing and X-ray testing. Furthermore, eddy current testing requires no coupling agent and allows for rapid and continuous testing. Eddy current testing utilizes the principle of electromagnetic induction, passing a medium-frequency excitation current through an eddy current coil, generating an induced current on the surface of the specimen. Defects on the specimen's surface affect the distribution of the induced current, which in turn affects the excitation current, causing changes in the excitation coil impedance and ultimately detecting defects. However, due to the skin effect, the induced current has difficulty penetrating deeply into the specimen, making eddy current testing more sensitive to surface defects.

[0004] In the related art, there has been a technical solution that combines eddy current coils and electromagnetic ultrasonic coils, which is usually used to detect the thickness of test pieces. However, the defect of this solution is that the position setting of its eddy current coils is usually unreasonable. For example, the eddy current coil is located on the upper part of the probe sensor, and the electromagnetic ultrasonic coil is located at the lower part of the sensor. This design may be to reduce the mutual interference between the electromagnetic ultrasonic coil and the eddy current coil when generating electromagnetic induction. However, in this way, when in use, the eddy current coil is far away from the test piece. Even the thickness of the test cannot be detected very accurately, let alone the defect information on the surface and inside of the test piece. Therefore, the solutions in the related art have the problem of not being able to take into account both measurement accuracy and anti-interference between the two coils.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of the present invention is to provide a composite probe of electromagnetic ultrasound and eddy current and a working method thereof, which does not require coupling agent, can achieve rapid and non-contact measurement of the specimen, and more accurately obtain the surface and internal information of the specimen at the same time.

[0007] To solve the above problems, in a first aspect, an embodiment of the present invention provides an electromagnetic ultrasound and eddy current composite probe, characterized by comprising:

[0008] A shell, wherein a magnet is disposed inside the shell; an electromagnetic ultrasonic coil is disposed directly below the magnet, and an electromagnetic ultrasonic shielding layer is disposed between the electromagnetic ultrasonic coil and the magnet; an eddy current coil is wound around the outside of the eddy current shielding layer in the shell, with its bottom end flush with the electromagnetic ultrasonic coil and adjacent to the ceramic sheet, and the magnet is located inside the eddy current shielding layer; the eddy current coil leads and the electromagnetic ultrasonic coil leads are both led out through the reserved space in the shell and the eddy current shielding layer to facilitate connector connection.

[0009] Optionally, the geometric shape of the magnet is a cylinder, the direction of the magnetic pole is parallel to the axis of the cylinder, and it can generate a high-intensity magnetic field of 0.8-1T.

[0010] Optionally, the electromagnetic ultrasonic shielding layer is made of copper.

[0011] Optionally, the geometric shape of the electromagnetic ultrasonic coil is a planar spiral, and its size is slightly smaller than the bottom surface of the magnet.

[0012] Optionally, the electromagnetic ultrasonic coil can both generate and receive signals, and is a transceiver integrated coil.

[0013] Optionally, the excitation current signal passed into the electromagnetic ultrasonic coil is a high-frequency current with a frequency of 1 to 3 MHz.

[0014] Optionally, the eddy current coil can both generate and receive signals, and is a transceiver integrated coil.

[0015] Optionally, the excitation current flowing into the eddy current coil is a medium frequency current with a frequency of 1 to 3 kHz.

[0016] Optionally, the material of the eddy current shielding layer is iron.

[0017] Optionally, the geometric shape of the ceramic sheet is circular and the thickness does not exceed 3 mm.

[0018] In a second aspect, an embodiment of the present invention provides a method for operating the above-mentioned electromagnetic ultrasound and eddy current composite probe, comprising:

[0019] A signal generator is used to generate medium-frequency and high-frequency excitation currents. The excitation currents pass through the electromagnetic ultrasonic coil impedance matching circuit and the eddy current coil impedance matching circuit respectively. After the signal strength is increased, the electromagnetic ultrasonic and eddy current composite probe is driven to simultaneously generate eddy current signals and electromagnetic ultrasonic signals. The eddy current signals interact with the surface defects of the test piece and are sensed by the eddy current coil. The electromagnetic ultrasonic signals interact with the internal defects of the test piece and are sensed by the electromagnetic ultrasonic coil. The electrical signal coupling between them is removed by passing through the electromagnetic ultrasonic signal high-pass filter and the eddy current signal low-pass filter respectively. The signal characteristics are then amplified by the amplifier circuit. Finally, the defect information carried is displayed on the multi-channel oscilloscope after passing through the signal processing module.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The composite probe of electromagnetic ultrasound and eddy current of the present invention integrates electromagnetic ultrasound and eddy current probes on the same probe. Eddy current signals interact with surface defects of the test piece and are sensed by the eddy current coil, while electromagnetic ultrasound signals interact with internal defects of the test piece and are sensed by the electromagnetic ultrasound coil. Only one test is required to realize simultaneous detection of the interior and surface of the test piece, and the test piece has comprehensive detection. At the same time, the probe has the characteristics of small size and easy portability.

[0022] The composite probe of electromagnetic ultrasound and eddy current of the present invention has the advantage of being non-contact due to the use of electromagnetic coupling for energy and information conversion, thus simplifying the detection process and greatly improving the detection efficiency.

[0023] In the composite probe of electromagnetic ultrasound and eddy current of the present invention, the frequencies of the excitation signals of electromagnetic ultrasound and eddy current differ greatly, so it is easy to extract the required signal from the mutually coupled received signals, thereby improving the detection accuracy.

[0024] The composite probe of electromagnetic ultrasound and eddy current of the present invention has an eddy current coil wound around the outside of the eddy current shielding layer and separated from the electromagnetic ultrasonic coil. An electromagnetic ultrasonic shielding layer is also provided above the electromagnetic ultrasonic coil. This ensures that both the electromagnetic ultrasonic coil and the eddy current coil can be set close to the test piece to accurately measure defects on the surface and inside of the test piece. At the same time, it can also reduce the mutual influence between the eddy current coil and the electromagnetic ultrasonic coil under electromagnetic induction, solving the contradiction of being unable to take into account both measurement accuracy and anti-interference between the two coils.

[0025] The working method of the electromagnetic ultrasonic and eddy current composite probe of the present invention effectively separates the mutually coupled and interfering eddy current signals and electromagnetic ultrasonic signals, thereby improving the recognition characteristics of the eddy current signals and the electromagnetic ultrasonic signals and improving the detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1Schematic diagram of the overall structure of the electromagnetic ultrasound and eddy current composite probe provided by an embodiment of the present invention.

[0027] Figure 2 Schematic diagram of the structure of the eddy current shielding layer wound around the eddy current coil of the probe provided in an embodiment of the present invention.

[0028] Figure 3 This is a bottom view of the probe housing structure provided by an embodiment of the present invention.

[0029] Figure 4 This is a structural diagram of the electromagnetic ultrasonic coil of the probe provided in an embodiment of the present invention.

[0030] Figure 5 A schematic diagram of the structure of a test system matching the probes provided in an embodiment of the present invention.

[0031] Among them: 1- eddy current coil; 2- eddy current shielding layer; 3- electromagnetic ultrasonic coil; 4- ceramic sheet; 5- electromagnetic ultrasonic shielding layer; 6- strong magnet; 7- shell; 8- top cover; 9- electromagnetic ultrasonic coil lead wire; 10- eddy current coil lead wire. DETAILED DESCRIPTION

[0032] The principles and spirit of the present invention will be described below with reference to several exemplary embodiments shown in the accompanying drawings. It should be understood that these embodiments are described only to enable those skilled in the art to better understand and implement the present invention, and are not intended to limit the scope of the present invention in any way.

[0033] Please refer to Figure 1-4 An embodiment of the present invention provides a composite probe of electromagnetic ultrasound and eddy current, which can simultaneously excite eddy currents and elastic waves, and can detect the surface and interior of a test piece.

[0034] As an example, the composite probe of electromagnetic ultrasound and eddy current includes a shell, which is generally cylindrical. The top of the shell has a top cover, and the top cover is configured with an opening to allow the guiding electromagnetic ultrasound coil lead 9 and the eddy current coil lead 10 inside the shell to pass through, thereby facilitating the connection of the electromagnetic ultrasound coil 3 and the eddy current coil 1 to the signal power line at the end of the probe.

[0035] A cavity is constructed inside the shell 7, into which a cylindrical strong magnet 6 is placed. The magnetic pole direction of the strong magnet 6 is parallel to the axis of the cylinder, and it can generate a high-intensity magnetic field of 0.8-1 T. An electromagnetic ultrasonic shielding layer 5, an electromagnetic ultrasonic coil 3 and a ceramic sheet 4 are sequentially arranged at the bottom of the strong magnet 6, wherein the geometric shape of the electromagnetic ultrasonic coil 3 is a flat spiral, and its size is slightly smaller than the bottom surface of the strong magnet 6. With this design, the electromagnetic ultrasonic coil 3 can be relatively close to the test piece 11, and more accurate test piece detection information can be obtained. At the same time, the electromagnetic ultrasonic shielding layer 5 can also reduce the interference of the electromagnetic ultrasonic coil 3 on the eddy current coil 1. The material of the electromagnetic ultrasonic shielding layer 5 can be copper.

[0036] The outer shell of the strong magnet 6 is also provided with an eddy current coil shielding layer 2, and the eddy current coil 1 is wound on the outside of the eddy current shielding layer 2. The bottom end of the eddy current coil 1 is flush with the electromagnetic ultrasonic coil and adjacent to the ceramic sheet 4. In this way, the eddy current coil 1 and the shielding layer 2 of the test piece 11 are also cylindrical and tubular, and the inner wall thereof is grooved for the electromagnetic ultrasonic coil lead 9 to pass through, and the outer wall thereof is used to wind the eddy current coil 1. This structure makes the invented probe more compact and easy to get close to, and can accurately detect the information of the test piece 11. At the same time, the eddy current coil shielding layer 2 can also reduce the mutual interference between the eddy current coil 1 and the electromagnetic ultrasonic coil 3. The material of the eddy current shielding layer 2 is iron. As an example, eddy current is carried.

[0037] The eddy current coil lead 10 and the electromagnetic ultrasonic coil lead 9 are both led out through the reserved space in the housing 7 and the eddy current shielding layer 2 to facilitate joint connection.

[0038] As an example, the electromagnetic ultrasonic coil 3 can both generate and receive signals, acting as a transceiver. The excitation current signal fed into it is a high-frequency current with a frequency of 1 to 3 MHz. The eddy current coil 1 can both generate and receive signals, acting as a transceiver. The excitation current fed into it is a medium-frequency current with a frequency of 1 to 3 kHz.

[0039] When a high-frequency alternating current is passed through the electromagnetic ultrasonic coil 3, under the action of the strong magnet 6, a transverse wave is generated in the test piece 11 directly below the electromagnetic ultrasonic coil 3 and propagates into the test piece 11. When encountering a geometric mutation or a material mutation, an echo will be generated. The echo will be received by the electromagnetic ultrasonic coil 3, causing the induced electromotive force of the electromagnetic ultrasonic coil 3 to change, thereby completing the detection.

[0040] When a medium-frequency alternating current is passed through the eddy current coil 1, an induced current will be generated on the surface of the test piece 11 below the eddy current coil 1. Defects on the surface of the test piece 11 will cause changes in the geometric shape of the test piece 11, thereby affecting the distribution of current on the surface of the test piece 11. The changes in the current on the surface of the test piece 11 will be received by the eddy current coil 1, thereby completing the detection.

[0041] like Figure 5As shown, the experimental system for matching the composite probe of electromagnetic ultrasound and eddy current of the present invention includes a signal generator, an impedance matching circuit of the electromagnetic ultrasound coil and the eddy current coil, a composite probe, an eddy current signal low-pass filter circuit and an electromagnetic ultrasound signal high-pass filter circuit, a signal amplification circuit, a signal processing module and a multi-channel oscilloscope connected in a logical sequence; the signal generator is used to generate intermediate frequency and high frequency excitation currents, which respectively pass through the electromagnetic ultrasound coil impedance matching circuit and the eddy current coil impedance matching circuit to increase the signal strength, and then drive the composite probe of electromagnetic ultrasound and eddy current to simultaneously generate eddy current signals and electromagnetic ultrasound signals. The eddy current signals interact with the surface defects of the specimen and are sensed by the eddy current coil 1. The electromagnetic ultrasound signals interact with the internal defects of the specimen and are sensed by the electromagnetic ultrasound coil 3. The electrical signal coupling between them is decoupled by the electromagnetic ultrasound signal high-pass filter and the eddy current signal low-pass filter, and then the signal characteristics are amplified by the amplification circuit. Finally, the signal processing module can display the defect information carried on the multi-channel oscilloscope. The composite probe of electromagnetic ultrasonic and eddy current overcomes the shortcomings of eddy current probe detection being insensitive to the interior of the material and electromagnetic ultrasonic detection being insensitive to the surface of the material. It can also separate the mutually coupled and interfering eddy current signals and electromagnetic ultrasonic signals, thereby improving detection efficiency and accuracy.

[0042] This document uses specific examples to illustrate the inventive concept in detail. The above embodiments are only intended to help understand the core concept of the present invention. It should be noted that any obvious modifications, equivalent substitutions, or other improvements made by a person skilled in the art without departing from the inventive concept should be included within the scope of protection of the present invention.

Claims

1. A composite probe of electromagnetic ultrasound and eddy current, characterized in that: include: A housing (7) is provided with a magnet (6); an electromagnetic ultrasonic coil (3) is provided directly below the magnet (6), and an electromagnetic ultrasonic shielding layer (5) is provided between the electromagnetic ultrasonic coil (3) and the magnet (6); an eddy current coil (1) is wound around the outside of the eddy current shielding layer (2) in the housing (7), with its bottom end flush with the electromagnetic ultrasonic coil (3) and adjacent to the ceramic sheet (4), and the magnet (6) is located inside the eddy current shielding layer (2); eddy current coil leads (10) and electromagnetic ultrasonic coil leads (9) are both led out through reserved spaces in the housing (7) and the eddy current shielding layer (2) to facilitate joint connection; the ceramic sheet (4) is located below the eddy current coil (1) and the electromagnetic ultrasonic coil (3).

2. The electromagnetic ultrasound and eddy current composite probe according to claim 1, characterized in that: The magnet (6) has a cylindrical geometric shape, with the magnetic pole direction parallel to the cylindrical axis, and is capable of generating a high-intensity magnetic field of 0.8-1T.

3. The electromagnetic ultrasound and eddy current composite probe according to claim 1, characterized in that: The electromagnetic ultrasonic shielding layer (5) is made of copper.

4. The electromagnetic ultrasound and eddy current composite probe according to claim 1, characterized in that: The geometric shape of the electromagnetic ultrasonic coil (3) is a planar spiral, and its size is slightly smaller than the bottom surface of the magnet (6).

5. The electromagnetic ultrasound and eddy current composite probe according to claim 1, characterized in that: The electromagnetic ultrasonic coil (3) can both generate and receive signals and is a transceiver-integrated coil.

6. The electromagnetic ultrasound and eddy current composite probe according to claim 1, characterized in that: The excitation current signal passed into the electromagnetic ultrasonic coil (3) is a high-frequency current with a frequency of 1 to 3 MHz.

7. The electromagnetic ultrasound and eddy current composite probe according to claim 1, characterized in that: The eddy current coil (1) can both generate and receive signals, and is a transceiver-integrated coil.

8. The electromagnetic ultrasound and eddy current composite probe according to claim 1, characterized in that: The excitation current flowing into the eddy current coil (1) is a medium frequency current with a frequency of 1 to 3 kHz.

9. The electromagnetic ultrasound and eddy current composite probe according to claim 1, characterized in that: The material of the eddy current shielding layer (2) is iron.

10. A method for operating the electromagnetic ultrasound and eddy current composite probe according to any one of claims 1 to 9, characterized in that: include: A signal generator is used to generate medium-frequency and high-frequency excitation currents. The excitation currents pass through the electromagnetic ultrasonic coil impedance matching circuit and the eddy current coil impedance matching circuit respectively. After the signal strength is increased, the electromagnetic ultrasonic and eddy current composite probe is driven to simultaneously generate eddy current signals and electromagnetic ultrasonic signals. The eddy current signals interact with the surface defects of the test piece and are sensed by the eddy current coil. The electromagnetic ultrasonic signals interact with the internal defects of the test piece and are sensed by the electromagnetic ultrasonic coil. The electrical signal coupling between them is removed by passing through the electromagnetic ultrasonic signal high-pass filter and the eddy current signal low-pass filter respectively. The signal characteristics are then amplified by the amplifier circuit. Finally, the defect information carried is displayed on the multi-channel oscilloscope after passing through the signal processing module.

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