Co-excitation type pulsed eddy current thickness measurement and flaw detection composite sensor

Abstract

The invention belongs to the technical field of pulsed eddy current detection, and particularly discloses a co-excitation type pulsed eddy current thickness measurement and flaw detection composite sensor. The sensor comprises a shell, and the shell is internally provided with an excitation coil used for exciting a pulsed eddy current magnetic field in a measured object; the absolute receiving coil coaxially sleeves the peripheral surface of the excitation coil and is used for sensing the pulsed eddy current magnetic field and outputting a thickness measuring signal for reflecting the thickness change of the measured object; the differential receiving coil comprises two sub-coils which are respectively arranged at the two radial ends of the absolute receiving coil, and the dotted terminals of the two sub-coils are connected and jointly used for sensing a pulsed eddy current magnetic field and outputting defect signals for reflecting defects of a detected object. According to the sensor, thickness measurement and flaw detection can be carried out on a detected object at the same time, and the detection sensitivity is extremely high.

Description

Technical Field

[0001] The present application belongs to the field of pulsed eddy current detection technology, and more specifically, relates to a co-excitation pulsed eddy current thickness measurement and flaw detection composite sensor. Background Art

[0002] Eddy current testing is a nondestructive testing technology based on the principle of electromagnetic induction. It is primarily used to detect surface and near-surface defects in conductive materials (such as metals), measure material thickness, and distinguish material properties. Pulsed eddy current testing, a key branch of eddy current testing, offers a richer frequency component and greater signal penetration than conventional eddy current testing, enabling detection of deeper defects and enabling thinning detection at greater liftoff.

[0003] In the related art, the use of traditional pulsed eddy current sensors has great limitations. For example, the Chinese patent application with publication number CN106441068A discloses a pulsed eddy current sensor for wall thickness detection. This pulsed eddy current sensor can only output the thickness of the object being measured. The detection sensitivity for flaw detection is not high, and it is relatively limited in actual application scenarios. For another example, the Chinese patent application with publication number CN101581699A discloses a pulsed eddy current non-destructive testing method based on time gate. This method suppresses the electromagnetic field interference problem between coils in different channels through time-sharing excitation. However, it is difficult to collect thickness signals and defect signals at the same time, and it is in urgent need of improvement. Summary of the Invention

[0004] In response to the defects or improvement needs of the existing technology, the present application provides a co-excitation pulsed eddy current thickness measurement and flaw detection composite sensor, which aims to solve the problem that traditional pulsed eddy current sensors have large limitations in use and are difficult to simultaneously collect thickness signals and defect signals.

[0005] The present application provides a co-excitation pulsed eddy current thickness measurement and flaw detection composite sensor, specifically comprising a housing, wherein the housing is provided with: An excitation coil, used to excite a pulsed eddy current magnetic field in the object being measured; The absolute receiving coil is coaxially sleeved on the outer peripheral surface of the excitation coil, and is used to induce the pulsed eddy current magnetic field and output a thickness measurement signal to reflect the thickness change of the object being measured; The differential receiving coil comprises two sub-coils respectively arranged at the radial ends of the absolute receiving coil. The two sub-coils are connected at the same ends and are used to induce a pulsed eddy current magnetic field and output a defect signal for reflecting defects of the object being measured.

[0006] Through the above technical solution conceived by the present application, compared with traditional technologies, since the sensor integrates the excitation coil, the absolute receiving coil and the differential receiving coil in the shell, and arranges each coil in a specific position, when using the sensor, based on the excitation effect of the excitation coil, the absolute receiving coil and the differential receiving coil can be co-excited, so that the sensor can accurately output the defect information and thickness information of the object under test at the same time, achieving the effect of completing dual-function high-precision detection in a single scan.

[0007] Compared with traditional designs, this sensor can achieve simultaneous thickness measurement and flaw detection of the object being measured, and can provide multiple detection data of the same period and the same part for the entire detection process. This is conducive to the detection personnel to complement and integrate multi-dimensional data in subsequent detection analysis, make comprehensive judgments, avoid the limitations of a single detection mode, reduce the misjudgment rate, and thus improve detection accuracy and reliability.

[0008] In particular, when using this sensor, the differential receiving coil eliminates environmental noise, differentially canceling common-mode signals such as power frequency interference and vibration noise, improving the signal-to-noise ratio. The absolute receiving coil, on the other hand, retains global information, enabling the sensor to operate stably in industrial environments (such as those subject to strong electromagnetic interference and vibration), effectively adapting to complex detection conditions.

[0009] As a further preference, the outer diameter of the excitation coil is 2 to 3 times the inner diameter of the excitation coil, and the height of the excitation coil is 1.5 to 2 times the inner diameter of the excitation coil.

[0010] As a further preference, the inner diameter of the absolute receiving coil is 1mm-2mm larger than the outer diameter of the excitation coil, the outer diameter of the absolute receiving coil is 10mm-20mm larger than the inner diameter of the absolute receiving coil, and the height of the absolute receiving coil is 3mm-6mm.

[0011] As a further preference, the height of the sub-coil is 1 to 2 times the height of the excitation coil, the outer diameter of the sub-coil is 0.15 to 0.3 times the height of the sub-coil, and the inner diameter of the sub-coil is 0.5 to 0.7 times the outer diameter of the sub-coil.

[0012] As a further preference, a gap is left between the sub-coil and the absolute receiving coil.

[0013] As a further preference, the sensor further includes a ferrite core, and the ferrite core is arranged inside the sub-coil.

[0014] As a further preferred embodiment, the sensor further includes a wiring socket, wherein: The excitation coil is used to connect to an external pulse signal generating device through a wiring socket; The absolute receiving coil and the differential receiving coil are used to be connected to an external data processing device through a wiring socket, so as to simultaneously output a thickness measurement signal and a defect signal to the data processing device.

[0015] As a further preferred embodiment, the shell includes a main shell, an upper cover and a connecting piece, the main shell has a mounting cavity with an opening, the upper cover is detachably covered on the outer end of the opening through the connecting piece, and the terminal block is passed through and fixed on the upper cover.

[0016] As a further preference, the differential receiving coil is capable of signal zeroing and is arranged on the inner bottom wall of the installation cavity.

[0017] As a further preference, the shell is made of non-magnetic conductive material.

[0018] In general, the above technical solutions conceived by this application have the following technical advantages compared with the existing technologies: 1. This sensor integrates an excitation coil, an absolute receiving coil, and a differential receiving coil. By designing the dimensions of each coil and placing a ferrite core within the sub-coil of the differential receiving coil to focus the magnetic field, the sensor can simultaneously and accurately output both defect information and thickness information of the object being measured, achieving dual-function, high-precision detection in a single scan.

[0019] 2. The sensor's housing is made of non-magnetic and conductive materials, which prevents any impact on the pulsed eddy current detection signal. The differential receiving coil can be zeroed, resulting in extremely high sensitivity for defect detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the structure of a co-excitation pulsed eddy current thickness measurement and flaw detection composite sensor provided in an embodiment of the present application; Figure 2 yes Figure 1 Cross-sectional view along line AA; Figure 3 The differential output signal of the sensor before and after zeroing provided in the embodiment of the present application; Figure 4 Schematic diagram of the thickness measurement signal of the sensor provided in the embodiment of the present application when measuring 8mm and 10mm plates; Figure 5 This is a schematic diagram of the output signal obtained when the sensor provided in an embodiment of the present application measures a Φ5mm flat-bottom hole defect.

[0021] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1. Shell; 1-1. Main shell; 1-2. Upper cover; 1-3. Connectors; 2. Excitation coil; 3. Absolute receiving coil; 4. Sub-coil; 5. Terminal block; 6. Ferrite core; 10. Object under test; 10-1. Defective part. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0023] The following is combined with Figure 1-Figure 5 This application is described in further detail.

[0024] The present application discloses a co-excitation pulsed eddy current thickness measurement and flaw detection composite sensor. Figure 1 The co-excitation pulse eddy current thickness measurement and flaw detection composite sensor includes a shell 1, in which an excitation coil 2, an absolute receiving coil 3 and a differential receiving coil are arranged, wherein the excitation coil 2 is used to excite a pulse eddy current magnetic field in the object under test 10; the absolute receiving coil 3 is coaxially sleeved on the outer peripheral surface of the excitation coil 2, and is used to induce the pulse eddy current magnetic field and output a thickness measurement signal for reflecting the thickness change of the object under test 10; the differential receiving coil includes two sub-coils 4 respectively arranged at the radial ends of the absolute receiving coil 3, and the two sub-coils 4 are connected at the same ends and are jointly used to induce the pulse eddy current magnetic field and output a defect signal for reflecting the defects of the object under test 10.

[0025] Preferably, in some embodiments, the outer diameter of the excitation coil 2 is 2 to 3 times the inner diameter of the excitation coil 2, and the height of the excitation coil 2 is 1.5 to 2 times the inner diameter of the excitation coil 2. The inner diameter of the absolute receiving coil 3 is 1 mm to 2 mm larger than the outer diameter of the excitation coil 2, the outer diameter of the absolute receiving coil 3 is 10 mm to 20 mm larger than the inner diameter of the absolute receiving coil 3, and the height of the absolute receiving coil 3 is 3 mm to 6 mm. The height of the sub-coil 4 is 1 to 2 times the height of the excitation coil 2, the outer diameter of the sub-coil 4 is 0.15 to 0.3 times the height of the sub-coil 4, and the inner diameter of the sub-coil 4 is 0.5 to 0.7 times the outer diameter of the sub-coil 4. A gap is left between the sub-coil 4 and the absolute receiving coil 3.

[0026] Preferably, in some specific embodiments, the excitation coil 2 has an inner diameter of 15 mm, an outer diameter of 45 mm, and a height of 30 mm. Generally speaking, the taller the excitation coil 2 and the greater the number of turns, the stronger the eddy current field generated, but this also increases the coil impedance. In this design, by designing the excitation coil 2 with the aforementioned dimensions, the excitation coil 2 can generate sufficient eddy current field strength within a suitable impedance range for easy detection.

[0027] Preferably, the absolute receiving coil 3 has an inner diameter of 46 mm, an outer diameter of 60 mm, and a height of 3 mm. Generally speaking, the absolute receiving coil 3 and the excitation coil 2 should fit together as closely as possible, with the outer circumferential gap between the absolute receiving coil 3 and the excitation coil 2 not exceeding 2 mm.

[0028] Under this design, the closer to the object under test 10, the greater the intensity of the pulsed eddy current magnetic field. By designing the absolute receiving coil 3 as a flat, smaller coil, the number of turns are concentrated in the area with a smaller height. This can improve the utilization efficiency of each turn of the coil, allowing the absolute receiving coil 3 to sensitively detect the average wall thickness of the object under test 10.

[0029] Preferably, in the differential receiving coil, the inner diameter of the sub-coil 4 is 8 mm, the outer diameter is 15 mm, the height is 60 mm, the center distance between the sub-coil 4 and the excitation coil 2 (the straight-line distance between the center points of the two coils) is not less than 38 mm, and the turn directions of the two sub-coils 4 are consistent.

[0030] In this design, sub-coil 4 is designed with smaller inner and outer diameters and a higher height, effectively increasing the number of turns. This minimizes the effective coverage area of the differential receiving coil, ensuring sufficient spatial resolution and extremely high sensitivity. Furthermore, the center-to-center distance between sub-coil 4 and excitation coil 2 can reduce electromagnetic interference between the two receiving coils.

[0031] Furthermore, in some embodiments, the sensor further includes a cylindrical ferrite core 6 disposed within the sub-coil 4. The diameter of the ferrite core 6 is substantially the same as the inner diameter of the differential receiving coil, and the gap between the ferrite core 6 and the inner circumference of the sub-coil 4 does not exceed 1.5 mm. Preferably, the ferrite core 6 is made of manganese-zinc ferrite.

[0032] Under this design, the focusing ability of the ferrite core 6 on the magnetic field can be used to increase the pulse eddy current magnetic field intensity in the area above the differential receiving coil, thereby improving the detection sensitivity of the common excitation coil pulse eddy current thickness measurement and flaw detection integrated sensor to defects.

[0033] In practice, in this design, the absolute receiving coil 3 is placed in close proximity to the outer circumference of the excitation coil 2, while the differential receiving coil is positioned at a distance (as indicated by the aforementioned center-to-center distance design). This effectively minimizes interference between the two receiving coils. However, positioning the receiving coil away from the excitation coil 2 weakens the magnetic field, making it difficult to detect defect signals. Therefore, by optimizing the coil dimensions and adding a magnetic core (manganese-zinc ferrite), this sensor achieves excellent results for both thickness measurement and flaw detection.

[0034] Furthermore, in some embodiments, the sensor also includes a terminal block 5, wherein: the excitation coil 2 is used to connect to an external pulse signal generating device through the terminal block 5, and a pulse signal is input to the excitation coil 2 through the pulse eddy current instrument, so that the excitation coil 2 excites a pulse eddy current magnetic field in the object under test 10. The absolute receiving coil 3 and the differential receiving coil are used to connect to an external data processing device through the terminal block 5 to simultaneously output a thickness measurement signal and a defect signal to the data processing device. The absolute receiving coil 3 transmits an induced voltage signal to the data processing device through the terminal block 5 as a thickness measurement signal; the differential receiving coil transmits a differential voltage signal to the data processing device through the terminal block 5 as a defect signal.

[0035] In some embodiments, the pulse signal generating device is a pulsed eddy current testing instrument, and the data processing equipment includes a host computer. The excitation coil 2 is connected to the pulsed eddy current testing instrument via a terminal block 5. The absolute receiving coil 3 and the differential receiving coil are both connected to the host computer via the terminal block 5. The host computer can simultaneously collect signals from the absolute receiving coil 3 and the differential receiving coil, and then comprehensively analyze the two signals, which can more accurately characterize defects than a single absolute receiving coil output signal or a single differential receiving coil output signal. Preferably, the terminal block 5 is a six-pin terminal block 5, two pins of which are connected to the excitation coil 2, two pins are connected to the absolute receiving coil 3, and two pins are connected to the sub-coil 4.

[0036] Further, such as Figure 1 As shown, in some embodiments, the housing 1 includes a main housing 1-1 and an upper cover 1-2. The main housing 1-1 has an installation cavity with an opening for accommodating the excitation coil 2, the absolute receiving coil 3, and the differential receiving coil. The upper cover 1-2 is detachably mounted on the outer end of the opening of the main housing 1-1 for opening and closing the opening. The main housing 1-1 is cylindrical.

[0037] Furthermore, in some embodiments, the shell 1 also includes a connector 1-3, and the upper cover 1-2 is detachably connected to the main shell 1-1 through the connector 1-3. The connector 1-3 includes but is not limited to screws. When screws are used, it is preferred that a plurality of screws are provided, and they are evenly distributed on the outer peripheral edge of the upper cover 1-2. Among them, the upper cover 1-2 is provided with corresponding through holes for the rods of the screws to pass through; and the main shell 1-1 is provided with corresponding threaded holes for connecting with the screws. Of course, in some other embodiments, a connection scheme such as a snap-on connection or a buckle connection can be adopted between the upper cover 1-2 and the main shell 1-1, and the connector 1-3 may not be required in this case.

[0038] Preferably, the main shell 1-1, upper cover 1-2 and connecting parts 1-3 in the shell 1 are all made of non-magnetic conductive materials. This setting makes the shell 1 have good insulation performance and is not easy to interfere with the electromagnetic performance of the sensor.

[0039] Furthermore, in some embodiments, the excitation coil 2, absolute receiving coil 3, and differential receiving coil are all disposed on the inner bottom wall of the main housing 1-1, and the terminal block 5 is passed through and fixed to the upper cover 1-2. The main housing 1-1 is preferably cylindrical, with the excitation coil 2 disposed at the center of the inner bottom wall of the main housing 1-1. The absolute receiving coil 3 is coaxially sleeved around the outer periphery of the excitation coil 2, with the inner wall of the absolute receiving coil 3 in contact with the outer wall of the excitation coil 2. The two sub-coils 4 of the differential receiving coil are disposed at radial ends of the excitation coil 2.

[0040] Furthermore, in some embodiments, the differential receiving coil can be signal-zeroed and disposed on the inner bottom wall of the main housing 1-1. By performing signal zeroing on the differential receiving coil, manufacturing errors of the coil can be offset, which is beneficial to improving the sensitivity and accuracy of detection.

[0041] Generally speaking, the zero adjustment of the differential receiving coil can be performed by adjusting the position of the differential receiving coil (eg, fine-tuning the center distance between the sub-coil 4 and the excitation coil 2 ).

[0042] Usually, when adjustment is needed, the structural size of the sub-coil 4 remains unchanged. After the position of the sub-coil 4 is adjusted, the position of the sub-coil 4 is fixed with hot melt adhesive so that the sub-coil 4 is adhered to the main shell 1-1 through the hot melt adhesive.

[0043] Generally speaking, the position of sub-coil 4 only needs to be adjusted once; subsequent measurements do not require further adjustment. When zeroing is complete, the output defect signal (i.e., differential voltage signal) should be zero or very close to zero in the absence of external excitation or when the measured physical quantity is zero. Typically, a threshold is pre-set; zeroing is considered successful when the signal is within this range.

[0044] The implementation principle of the co-excitation pulsed eddy current thickness measurement and flaw detection composite sensor of the present application is as follows: When testing is required, the sensor is placed on the object under test 10 and connected to the pulsed eddy current instrument and a host computer. Then, the pulsed eddy current instrument inputs positive and negative square wave excitation signals into the excitation coil 2. At the falling edge of the positive and negative square wave excitation signals, an eddy current field is excited in the object under test 10 below.

[0045] When the thickness of the object 10 changes or a defect is detected, the eddy current field within the object 10 changes. Both the absolute receiving coil 3 and the differential receiving coil can sense the pulsed eddy current magnetic field (i.e., the secondary magnetic field) generated by the eddy current field and reflect information about the object 10 in the output signal. The absolute receiving coil 3 is more sensitive to thickness measurement and can output thickness information of the object 10; the differential receiving coil is more sensitive to defects and can output defect information about the object 10.

[0046] For example, Figure 3 As shown in Figure 1, it is the differential output signal of the co-excitation pulsed eddy current thickness measurement and flaw detection composite sensor before and after zero adjustment. After zero adjustment, the differential signal output is close to 0.

[0047] For example, Figure 4 Figure 1 shows the thickness measurement signal obtained by a co-excitation pulsed eddy current composite sensor during a test. The lift-off (i.e., the vertical distance between the sensor and the surface of the object under test) was 10 mm. As shown in the figure, the red output signal corresponds to a 10 mm plate thickness and has a slower decay rate. The blue output signal corresponds to an 8 mm plate thickness and has a faster decay rate, indicating a more effective detection result.

[0048] For example, Figure 5 The figure shows the defect signal obtained when the co-excitation pulse eddy current thickness measurement and flaw detection composite sensor measures a flat bottom hole defect with a depth of 2mm and a diameter of 5mm in a 10mm thick plate. The position of the sensor directly above the defect part 10-1 is defined as the coordinate origin. Figure 1 Taking the sensor layout perspective shown in the figure as an example, the sensor is in the negative direction to the left and in the positive direction to the right, and five positions, -80mm, -40mm, 0mm, 40mm, and 80mm, are measured respectively. Since the distance between the sub-coil 4 and the defect is different at different positions, the magnitude and attenuation rate of the output signal are different. In the position without defects, the induced voltage of the two sub-coils 4 is the same, and the differential output is zero; in the position with defects, since the distance between the two sub-coils 4 and the defect is different at different positions, the magnitude and attenuation rate of the output signal obtained are different, as shown in the figure. Figure 5 It shows that the voltage changes at different positions are very obvious, which shows that the sensor has excellent sensitivity and positioning ability in defect detection.

[0049] Under this design, the sensor integrates an excitation coil 2, an absolute receiving coil 3, and a differential receiving coil in the shell 1, and arranges each coil in a specific position. When using the sensor, based on the excitation effect of the excitation coil 2, the absolute receiving coil 3 and the differential receiving coil can be co-excited, so that the sensor can accurately output the defect information and thickness information of the object being measured at the same time, achieving the effect of completing dual-function high-precision detection in a single scan.

[0050] Compared with traditional sensors, this sensor can achieve simultaneous thickness measurement and flaw detection of the object being measured, and can provide multiple detection data of the same period and the same part for the entire detection process. This is conducive to the detection personnel to complement and integrate multi-dimensional data in subsequent detection analysis, make comprehensive judgments, avoid the limitations of a single detection mode, reduce the misjudgment rate, and thus improve detection accuracy and reliability.

[0051] When using this sensor, the differential receiving coil eliminates environmental noise, offsetting common-mode signals such as power frequency interference and vibration noise, improving the signal-to-noise ratio. The absolute receiving coil 3 retains global information, enabling the sensor to operate stably in industrial environments (such as those with strong electromagnetic interference and vibration), adapting to complex detection conditions and achieving outstanding performance.

[0052] It should be understood that the absolute receiving coil 3 is mainly composed of a single coil, which directly induces magnetic field changes by itself.

[0053] It should be understood that the sub-coils 4 included in the differential receiving coil maintain consistent dimensional parameters (including inner diameter, outer diameter, height, and winding direction). The two coils are connected at the same end. When the magnetic field changes, the same end will simultaneously generate induced voltages of the same polarity. When there is a defect near the sensor, the induced voltages will differ in magnitude due to the different distances between the two sub-coils and the defect. As a result, the signal output by the differential receiving coil is a differential signal containing defect information (the difference between the two induced voltages).

[0054] It should be understood that the same-named ends of the two sub-coils are the endpoints of the same polarity of the induced electromotive force of each coil. Figure 1 In the figure, the ends with the same name are connected, that is, the upper ends of the two sub-coils 4 are connected (not shown in the figure).

[0055] It should be understood that expressions such as "include" and "may include" used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "include" and / or "have" may be interpreted as indicating a specific characteristic, number, operation, constituent element, component, or combination thereof, but may not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0056] It should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0057] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0058] In this application, unless otherwise specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they can refer to fixed connection, detachable connection, or integral connection; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0059] It is easy for those skilled in the art to understand that the above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A co-excitation pulsed eddy current thickness measurement and flaw detection composite sensor, characterized in that: The invention comprises a housing (1), wherein the housing (1) is provided with: An excitation coil (2) is used to excite a pulsed eddy current magnetic field in the object to be measured (10); An absolute receiving coil (3) is coaxially sleeved on the outer peripheral surface of the excitation coil (2) and is used to induce a pulsed eddy current magnetic field and output a thickness measurement signal for responding to thickness changes of the object to be measured (10); A differential receiving coil comprises two sub-coils (4) arranged at the radial ends of an absolute receiving coil (3), wherein the two sub-coils (4) are connected at the same ends and are used to induce a pulsed eddy current magnetic field and output a defect signal for responding to defects in a measured object (10).

2. The co-excitation pulsed eddy current thickness measurement and flaw detection composite sensor according to claim 1, characterized in that: The outer diameter of the excitation coil (2) is 2 to 3 times the inner diameter of the excitation coil (2), and the height of the excitation coil (2) is 1.5 to 2 times the inner diameter of the excitation coil (2).

3. The co-excitation pulsed eddy current thickness measurement and flaw detection composite sensor according to claim 2, characterized in that: The inner diameter of the absolute receiving coil (3) is 1mm-2mm larger than the outer diameter of the excitation coil (2), the outer diameter of the absolute receiving coil (3) is 10mm-20mm larger than the inner diameter of the absolute receiving coil (3), and the height of the absolute receiving coil (3) is 3mm-6mm.

4. The co-excitation pulsed eddy current thickness measurement and flaw detection composite sensor according to claim 3, characterized in that: The height of the sub-coil (4) is 1 to 2 times the height of the excitation coil (2), the outer diameter of the sub-coil (4) is 0.15 to 0.3 times the height of the sub-coil (4), and the inner diameter of the sub-coil (4) is 0.5 to 0.7 times the outer diameter of the sub-coil (4).

5. The co-excitation pulsed eddy current thickness measurement and flaw detection composite sensor according to claim 1, characterized in that: A gap is left between the sub-coil (4) and the absolute receiving coil (3).

6. The co-excitation pulsed eddy current thickness measurement and flaw detection composite sensor according to any one of claims 1 to 5, characterized in that: The sensor further comprises a ferrite core (6), which is arranged inside the sub-coil (4).

7. The co-excitation pulsed eddy current thickness measurement and flaw detection composite sensor according to any one of claims 1 to 5, characterized in that: The sensor also includes a terminal block (5), wherein: The excitation coil (2) is used to connect to an external pulse signal generating device through a wiring socket (5); The absolute receiving coil (3) and the differential receiving coil are used to be connected to an external data processing device via a wiring socket (5) so as to simultaneously output a thickness measurement signal and a defect signal to the data processing device.

8. The co-excitation pulsed eddy current thickness measurement and flaw detection composite sensor according to claim 7, characterized in that: The housing (1) comprises a main housing (1-1), an upper cover (1-2) and a connector (1-3); the main housing (1-1) has a mounting cavity with an opening; the upper cover (1-2) is detachably covered on the outer end of the opening via the connector (1-3); and the wiring seat (5) is passed through and fixed on the upper cover (1-2).

9. The co-excitation pulsed eddy current thickness measurement and flaw detection composite sensor according to claim 8, characterized in that: The differential receiving coil is capable of signal zeroing and is arranged on the inner bottom wall of the installation cavity.

10. The co-excitation pulsed eddy current thickness measurement and flaw detection composite sensor according to any one of claims 1 to 5, characterized in that: The housing (1) is made of a non-magnetic and electrically conductive material.

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