Wheel type eddy current detection probe and method

Abstract

The invention discloses a wheel type eddy current detection probe and method. The probe comprises a front wheel, a rear wheel, a telescopic spring clamping groove formed between the front wheel and the rear wheel, a linear eddy current array probe installed in the clamping groove, a handle and a probe circuit integration box. The telescopic spring clamping groove provides flexible pressure through a telescopic spring at the upper end, so that the probe protrudes out of the plane of the wheel bottom in a free state and can be compressed in a self-adaptive mode in the detection process, and therefore the constant lift-off height between the probe and the detection face can be kept on the plane or the curved face. The detection method comprises the steps of model selection according to curvature, assembly connection, resistance balance and phase adjustment, scanning according to a path shaped like a Chinese character'tian 'and the like. The method effectively solves the problems of low detection efficiency, large curved surface lift-off effect interference and poor automation compatibility in the prior art, and is particularly suitable for high-efficiency and high-precision nondestructive detection of large-area curved surface structures such as aircraft skins and the like.

Description

Technical Field

[0001] This invention relates to the field of nondestructive testing technology, and in particular to a wheel-type eddy current testing probe and its testing method for large-area planar and curved structures. Background Technology

[0002] Eddy current testing is a non-destructive testing method based on the principle of electromagnetic induction, widely used for detecting surface and near-surface defects in metallic materials. In the aviation field, as the external structure of an aircraft, the aircraft skin covers the entire outer surface. During flight, not only do aerodynamic loads act directly on the skin, but because the skin is connected to the aircraft frame structure through adhesives or rivets, it also bears multiple loads such as bending, torsion, and shear from the engine. Therefore, cracks often appear at the edges of the rivet holes on the skin.

[0003] When the skin is in the component condition, it is generally inspected using penetrant testing. However, when it is in service, due to the large area, thinness, and paint layer covering the surface of the skin, it is no longer suitable to use the original penetrant testing. Ultrasonic or radiographic testing is also not suitable for these reasons, and only eddy current testing can be used.

[0004] Currently, commonly used eddy current testing probes, such as pen-type, hook-type, and right-angle probes, have the following drawbacks: Low detection efficiency: The probe is small in size and has a limited scanning coverage area, making it unsuitable for rapid detection of large areas.

[0005] Lift-off effect sensitivity: During eddy current testing, the height between the probe and the surface being tested is called the lift-off height. The presence of lift-off alters the magnetic field lines reaching the tested component, changing the magnetic flux and thus affecting the coil impedance. Even a small lift-off can produce a significant impedance change, impacting damage assessment during eddy current testing. Currently, both fuselage and wing skins have a certain curvature, causing partial lift-off between the probe surface and the testing surface during skin testing with existing probes, thus affecting the interpretation of test results.

[0006] Poor automation compatibility: Existing eddy current detection probes all use sliding to move the probe during the detection of skin surfaces. The sliding movement method is difficult to integrate stably with automated equipment to achieve efficient and uniform scanning.

[0007] Therefore, there is a need for an eddy current testing probe and method that can balance high efficiency, high precision, and good automation compatibility. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention aims to provide a wheel-type eddy current detection probe and method, thereby solving the problems of low detection efficiency, significant impact of curved surface lift-off effect, and high difficulty in automation of existing technologies.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a wheel-type eddy current detection probe, comprising: Front wheel and rear wheel; telescopic spring slot, disposed between the front wheel and the rear wheel; A linear eddy current array probe is detachably mounted in the telescopic spring slot; The handle is connected to the support arm of the front and rear wheels for manual pushing or connection to an automated propulsion device; The probe circuit integration box is electrically connected to the linear eddy current array probe.

[0010] In one embodiment, the internal coils of the linear eddy current array probe are arranged in a single linear row, with dimensions of 40mm~60mm in length and 10mm~20mm in width.

[0011] In one embodiment, a telescopic spring is provided at the upper end of the telescopic spring slot, and the linear eddy current array probe is installed at the lower end. The full compression load of the telescopic spring is no more than 10 Newtons, and the spring length is 15~20mm. In the free state, the lower end face of the linear eddy current array probe protrudes 3.0mm~5.0mm from the horizontal plane of the bottom of the front and rear wheels; in the maximum compression state, the linear eddy current array probe can be recessed 3.0mm~5.0mm.

[0012] In one embodiment, the lower front end of the linear eddy current array probe has a 1×45° chamfer.

[0013] In one embodiment, the front and rear wheels are cylindrical wheels with a height equal to the length of the linear eddy current array probe and a diameter of φ60mm~φ80mm.

[0014] In one embodiment, the rear end of the handle has a small hole for secure connection with an automated propulsion device.

[0015] Secondly, the present invention provides a wheel-type eddy current detection method using the above-mentioned probe, comprising the following steps: Select the appropriate wheel-type eddy current testing probe based on the curvature of the object to be tested: when the curvature of the object to be tested is greater than 1 / 5, use a wheel-type eddy current testing probe with a wheel diameter of φ60mm to φ65mm; when the curvature of the area to be tested is less than 1 / 30, use a wheel-type eddy current testing probe with a wheel diameter of φ75mm to φ80mm.

[0016] Insert the eddy current array probe into the telescopic spring slot and connect the wheel-type eddy current detection probe to the eddy current detector using a standard interface probe cable.

[0017] The light-pressure wheel-type eddy current detection probe compresses the spring to ensure that the array probe fits the detection surface. Adjust the "balance" button of the eddy current detector to make the resistance of the internal bridge arm of the instrument equal to the resistance of the bridge arm formed by the probe-detection surface, achieving resistance balance; then adjust the "phase" button to adjust the interference signal to the horizontal direction.

[0018] Push the wheel-type eddy current detection probe in a "field" - shaped path for scanning. Each scanning path should overlap with the previous one by at least 5 mm. When manually detecting, the advancing speed should not be greater than 100 mm / s.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects: The present invention replaces sliding with a wheel-type rolling design, significantly improving the scanning efficiency. Moreover, the stability of rolling and the standardized interface design of the handle provide a solid foundation for integration with automated propulsion equipment, greatly reducing the difficulty of automation upgrading.

[0020] Through the design of the telescopic spring slot, the linear eddy current array probe has an adaptive ability. Whether on a plane or a curved surface, the spring can dynamically adjust to ensure that the probe maintains a constant lift-off height from the detection surface. This fundamentally eliminates the unbalance of the bridge arm resistance and signal fluctuations caused by changes in the lift-off height, greatly improving the stability of the detection signal and the accuracy of defect discrimination.

[0021] Through the parametric design of the probe size and wheel diameter, as well as the replaceable feature of the probe, the probe can be flexibly adapted to working scenarios with different curvatures and detection requirements, with strong versatility. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0023] Figure 1 It is a schematic structural diagram of the wheel-type eddy current detection probe provided by an embodiment of the present invention; Figure 2 It is a schematic flow diagram of the wheel-type eddy current detection method provided by an embodiment of the present invention; Figure 3 It is a schematic diagram of the "field" - shaped scanning path in an embodiment of the present invention; Figure 1 In the figure: 1 - telescopic spring slot; 2 - front wheel support arm; 3 - front wheel; 4 - linear eddy current array probe; 5 - rear wheel; 6 - rear wheel support arm; 7 - handle; 8 - telescopic spring. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0025] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] like Figure 1 As shown, an embodiment of the present invention provides a wheel-type eddy current detection probe, which includes: a telescopic spring slot 1, a front wheel support arm 2, a front wheel 3, a linear eddy current array probe 4, a rear wheel 5, a rear wheel support arm 6, a handle 7, and a telescopic spring 8.

[0027] The front wheel 3 and rear wheel 5 are mounted on the probe body via the front wheel support arm 2 and rear wheel support arm 6, forming a stable double-wheel support structure. By using a wheel structure, traditional sliding friction is transformed into rolling friction, significantly reducing propulsion resistance and improving the efficiency of manual detection. The rolling forward motion is smooth and uniform, laying a solid foundation for stable connection with automated propulsion devices and achieving precise scanning. The telescopic spring slot 1 is rigidly connected between the front and rear wheel support arms, serving as the mounting base and motion guide mechanism for the linear eddy current array probe 4. The linear eddy current array probe 4 is detachably mounted in this slot. The replaceable design of the linear eddy current array probe 4 allows users to flexibly select different specifications of array probes according to different detection needs (such as resolution and detection depth), enhancing the versatility of the equipment. The handle 7 is fixedly connected to the support arm, serving as a force point for manual operation and also as an interface for automated integration. The probe circuit integration box (not shown in the figure, usually integrated into the handle or support arm) is electrically connected to the linear eddy current array probe 4 via a cable, enabling preliminary processing and transmission of the raw signals acquired by the probe.

[0028] In this embodiment of the invention, the internal detection coils (such as wafers) of the linear eddy current array probe 4 are arranged in a single linear row. The preferred dimensions of the linear eddy current array probe 4 are a length of 40mm to 60mm and a width of 10mm to 20mm. This size design ensures that a sufficient number of coils can be arranged to achieve high detection efficiency, while avoiding an excessively large probe size that would make the entire device bulky and inconvenient to operate on complex curved surfaces. The lower front end of the linear eddy current array probe 4 has a 1×45° chamfer, forming a smooth transition surface, which facilitates the probe's engagement with the detection surface as it advances.

[0029] In this embodiment of the invention, the telescopic spring 8 is installed at the upper end of the telescopic spring slot 1, and the lower end of the telescopic spring 8 acts on the linear eddy current array probe 4. The load of the telescopic spring 8 when fully compressed is no more than 10 Newtons, ensuring moderate pressure on the workpiece surface. This prevents the probe from jumping off the surface during rapid movement due to insufficient pressure, and also prevents excessive pressure from wearing the probe or hindering rolling. For example, the length of the telescopic spring 8 is 15-20 mm to provide sufficient buffer stroke.

[0030] In the free state, the preload of the telescopic spring 8 causes the detection surface of the probe 4 to protrude 3.0mm~5.0mm above the bottom horizontal plane of the front and rear wheels, ensuring that the probe is in the "ready to contact" state before contacting the workpiece.

[0031] In the detection state, the spring is compressed when the wheel presses on the workpiece. Regardless of whether the detection surface is an ideal flat surface or a curved surface, this spring mechanism allows the probe detection surface to adaptively adhere to the workpiece surface, dynamically maintaining a nearly constant lift height. When encountering protrusions or large curvature changes, the probe can retract 3.0mm~5.0mm to avoid rigid collisions.

[0032] By setting a telescopic spring to ensure that the probe maintains a consistent lift height from the detection surface during the detection state, the resistance of the detection bridge arm formed by the probe and the workpiece is kept stable. This ensures that the changes in the eddy current detection signal truly reflect the defects of the workpiece itself, greatly reducing misjudgments and missed judgments caused by lift fluctuations, and significantly improving the reliability and accuracy of the detection.

[0033] In this embodiment of the invention, the front wheel 3 and the rear wheel 5 are preferably cylindrical wheels, with their height being the same as the length of the linear eddy current array probe 4, providing stable support for the probe throughout its entire range and preventing the probe from tilting during scanning. Furthermore, the front wheel 3 and the rear wheel 5 preferably have the same wheel diameter to ensure that the probe remains horizontally stable during detection, thereby ensuring the consistency of the lifting height between the linear eddy current array probe 4 and the detection surface. For example, the wheel diameter is preferably φ60mm~φ80mm; a wheel diameter that is too small will result in low rotational efficiency; a wheel diameter that is too large will increase the weight and volume of the entire probe, which is detrimental to the detection operation.

[0034] In this embodiment of the invention, the handle 7 has a small hole at its rear end, providing a standardized, mechanical connection point. When performing automated testing, the automated propulsion device (such as the push rod at the end of a robotic arm) can be directly connected to this small hole through fasteners such as pins, achieving a fast, stable, and reliable rigid connection. This greatly simplifies the automation integration process and has good automation compatibility.

[0035] In the aforementioned wheeled eddy current testing probe structure, the front wheel 3 and the rear wheel 5 together form the moving base of the wheeled eddy current testing probe. During testing, the operator pushes the handle 7, or the probe structure is driven by automated equipment. The driving force is transmitted to the front wheel 3 and the rear wheel 5 through the front wheel support arm 2 and the rear wheel support arm 6, causing them to roll on the testing surface. Since both the front and rear wheels are cylindrical and have line contact with the testing surface, the original sliding friction can be transformed into low-resistance rolling friction, thereby achieving smooth and uniform rolling forward of the probe on the testing surface. This design not only reduces propulsion resistance and facilitates manual operation, but more importantly, it provides a stable and controllable motion base for automated scanning, avoiding the shaking and jamming problems that may occur with sliding. The linear eddy current array probe 4 is located between the front and rear wheels. Its testing surface remains in contact with the workpiece surface under the action of the telescopic spring 8, achieving continuous and stable scanning of the inspected area during the overall rolling forward of the probe.

[0036] This invention also provides a wheel-type eddy current detection method, which uses the aforementioned probe. The detection method will be described in detail below using aircraft skin inspection as an example. Figure 2 As shown, the detection method includes the following steps: Step S1: Probe Selection The operator first assesses the curvature of the skin to be inspected. If the skin curvature is large, a wheel-type eddy current testing probe with a smaller wheel diameter (e.g., φ60mm) is selected. The smaller wheel diameter allows the probe to be closer to the curved surface, enabling the linear eddy current array probe in the center to couple better with the surface and preventing the wheel from "lifting" the probe. If the skin is relatively flat, a wheel-type eddy current testing probe with a larger wheel diameter (e.g., φ80mm) is selected. The larger wheel diameter results in higher rolling efficiency and a larger scanning area per unit time, thereby improving testing efficiency.

[0037] In a preferred embodiment of the present invention, in step S1 (probe selection), the operator can make a precise selection based on the specific curvature value of the object to be tested: When the object being tested is an area with a large curvature (curvature greater than 1 / 5), such as the leading edge of the wing or the perimeter of the fuselage door, a wheeled eddy current detection probe with a wheel diameter of φ60mm to φ65mm (e.g., φ62mm) should be preferred to ensure that the linear eddy current array probe 4 can fully fit the curved surface and to avoid the wheel "lifting" the probe. Probes with smaller wheel diameters have better steering flexibility and adaptability to curved surfaces.

[0038] When inspecting areas with very low or relatively flat curvature (curvature less than 1 / 30), such as the middle of the wing or most of the fuselage, wheel-type eddy current testing probes with a diameter of φ75mm to φ80mm (e.g., φ78mm) should be preferred to achieve the highest inspection efficiency and smooth propulsion. Larger diameter probes have higher rolling efficiency and less vibration on flat surfaces.

[0039] By using the curvature-based quantitative selection method described above, it can be ensured that the wheel-type eddy current detection probe can achieve the best balance between detection efficiency and detection accuracy (fit) in any detection scenario.

[0040] Step S2: Probe assembly and connection Insert the linear eddy current array probe 4 into the telescopic spring slot 1 of the selected wheel-type eddy current detection probe until it is locked in place. Then, using a probe cable with a standard interface (such as a Lemo interface, BNC interface, or Fischer interface) on one end, firmly connect the probe circuit integration box in the wheel-type eddy current detection probe to the eddy current detector. The use of a standard interface ensures the universality and reliability of the connection.

[0041] Step S3: Instrument Calibration Gently place the probe on the standard test block or the skin to be inspected, and lightly press down on the handle 7 to moderately compress the telescopic spring 8, ensuring that the bottom surface of the linear eddy current array probe 4 is completely in contact with the inspection surface. Then, adjust the "balance" button on the eddy current detector to make the reference bridge arm resistance value inside the eddy current detector equal to the actual bridge arm resistance value formed by the "probe-inspection surface" at the current constant lift-off height, achieving resistance balance and minimizing interference from the lift-off signal. Next, adjust the "phase" button to rotate the remaining surface interference signals (such as minor changes caused by uneven paint thickness) to the horizontal direction of the signal, thereby more clearly highlighting defect signals such as cracks in the vertical direction and eliminating interference signals.

[0042] Step S4: Scanning and Detection The operator moves the wheeled eddy current detection probe along the skin surface in a zigzag pattern to scan. The zigzag pattern ensures complete coverage of the detection area without omissions; for example, the zigzag scanning method can be referred to... Figure 3It is understood that the execution logic of this path is as follows: The operator first completes a series of horizontal scans, and then completes a series of vertical scans (vice versa), finally forming a "field" - shaped full coverage. Between every two adjacent horizontal scan paths and between every two adjacent vertical scan paths, they are connected by a short transition path to ensure that when the probe finishes one path and turns to the next path, its left - right or up - down orientation can quickly and coherently align with the new advancing direction, thus maintaining the stability of the detection posture. Those skilled in the art should understand that the specific length of the path in the attached drawings is only a symbolic representation, and the actual scan spacing and the length of the transition section should be determined according to the detection requirements. During scanning, each scan path needs to have at least 5 mm overlap with the previous one to compensate for possible path deviations and ensure that defects at the effective scan width boundary of the probe can also be effectively scanned. During manual detection, the advancing speed is not greater than 100 mm / s to ensure that the eddy current detector has sufficient data acquisition time, ensuring that the signal is not distorted, and thus ensuring the detection sensitivity.

[0043] The wheel - type eddy current detection probe and method provided by the present invention integrate the high efficiency of rolling forward, the constant lift - off control of the telescopic spring, and the large - area scanning ability of the linear array probe through the collaborative architecture of "wheel - type support - spring self - adaptation - linear array scanning", improving the detection efficiency and automation level, effectively solving the long - standing technical bottlenecks faced by traditional eddy current detection technology in the application of large - area planar and curved surface structures, providing a complete and reliable solution for achieving efficient, high - precision, and automation - friendly eddy current detection, and significantly enhancing the comprehensive ability of in - service non - destructive testing in the fields of aviation, aerospace, etc.

[0044] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, various changes and modifications can be made to the embodiments of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A wheel-type eddy current detection probe, characterized in that, Comprising: Front wheels (3) and rear wheels (5); A telescopic spring slot (1), arranged between the front wheels (3) and the rear wheels (5); A linear eddy current array probe (4), detachably mounted within the telescopic spring slot (1); A handle (7), connected to the support arms of the front wheels (3) and the rear wheels (5); A probe circuit integration box, electrically connected to the linear eddy current array probe (4); Wherein, a telescopic spring (8) is provided at the upper end of the telescopic spring slot (1), and the telescopic spring (8) is configured to: in a free state, make the lower end face of the linear eddy current array probe (4) protrude from the bottom horizontal plane of the front wheels (3) and the rear wheels (5); in a stressed state, be capable of adaptively compressing to keep the linear eddy current array probe (4) in contact with the detection surface.

2. The wheel-type eddy current detection probe according to claim 1, characterized in that, The internal coils of the linear eddy current array probe (4) are arranged in a single-column linear pattern, and the size of the linear eddy current array probe (4) is 40 mm to 60 mm in length and 10 mm to 20 mm in width.

3. The wheel-type eddy current detection probe according to claim 1, characterized in that, The full compression load of the telescopic spring (8) is not greater than 10 Newtons, and the length of the telescopic spring is 15 to 20 mm; in a free state, the protrusion amount of the linear eddy current array probe (4) is 3.0 mm to 5.0 mm; in a maximum compression state, the indentation amount of the linear eddy current array probe (4) is 3.0 mm to 5.0 mm.

4. The wheel-type eddy current detection probe according to claim 1, characterized in that, A 1×45° chamfer is provided at the lower front end of the linear eddy current array probe (4).

5. The wheel-type eddy current detection probe according to claim 1, characterized in that, The front wheels (3) and the rear wheels (5) are cylindrical wheels, having the same height as the length of the linear eddy current array probe (4), and the wheel diameter is φ60 mm to φ80 mm.

6. The wheel-type eddy current detection probe according to claim 1, characterized in that, A small hole for connecting to an automated propulsion device is provided at the rear end of the handle (7).

7. A wheel-type eddy current detection method employing a wheel-type eddy current detection probe as described in any one of claims 1-6, characterized in that, Including the following steps: Select a wheel-type eddy current detection probe according to the curvature of the object to be detected; Insert the linear eddy current array probe (4) into the telescopic spring slot (1) of the wheel-type eddy current detection probe, and use a standard interface probe wire to connect the wheel-type eddy current detection probe and the eddy current detector; Gently press the wheel-type eddy current detection probe to make the linear eddy current array probe (4) fit the detection surface, adjust the eddy current detector to achieve resistance balance, and adjust the phase to eliminate interference signals; Push the wheel-type eddy current detection probe in a "field" - shaped path for scanning, with an overlap for each scanning path, and the propulsion speed is not greater than 100 mm / s.

8. The method according to claim 7, characterized in that, The selecting a wheel-type eddy current detection probe according to the curvature of the object to be detected includes: When the curvature of the object to be detected is greater than 1 / 5, select a wheel-type eddy current detection probe with a wheel diameter of φ60 mm to φ65 mm; When the curvature of the area to be detected is less than 1 / 30, select a wheel-type eddy current detection probe with a wheel diameter of φ75 mm to φ80 mm.

9. The method according to claim 7, characterized in that, The repeated overlap spacing for each scanning during the scanning is not less than 5 mm.

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