A sensor for measuring the thickness of eddy current coatings with automatic attitude correction on complex curved surfaces

Abstract

The present invention relates to an eddy current coating thickness measurement sensor with automatic posture correction for complex curved surfaces, belonging to the field of non-destructive thickness measurement. A sensor for measuring the thickness of an eddy current coating with automatic posture correction for complex curved surfaces, the measuring sensor comprising a spring-pressing mechanism, a spring return cylinder, and a posture adjustment mechanism; the spring-pressing mechanism is placed in the spring return cylinder, serving as the piston of the spring return cylinder. When compressed gas enters the spring return cylinder, the spring-pressing mechanism extends the spring return cylinder under the action of gas pressure to complete the measurement of the coating thickness on the surface of the inspected workpiece; the posture adjustment mechanism is used to adjust the state between the spring return cylinder and the side surface to be inspected, so as to complete the overall posture adjustment and correction of the measuring sensor. The present invention has the following advantages: 1. It ensures that the measuring sensor generates a constant pushing force on the coating each time it measures; 2. It ensures that the measuring sensor measures vertically, while improving the measurement efficiency and accuracy of the measuring sensor.

Description

Technical Field

[0001] The invention relates to a sensor for measuring the thickness of an eddy current coating with automatic posture correction on a complex curved surface, and belongs to the field of non-destructive thickness measurement. Background Art

[0002] Aircraft require various coatings to enhance specific functional strength. The quality of the applied coatings is crucial to component performance, and a key indicator of this quality is the accuracy and uniformity of the coating thickness. Furthermore, due to the complex surface topography of aircraft components, maintaining vertical contact and stable measurement of the sensor's coating is crucial when measuring the coating. Therefore, achieving high-precision coating thickness measurement is crucial for improving component functionality and safety.

[0003] Currently, there are a variety of non-destructive measurement technologies for component coating thickness. Among them, ultrasonic thickness measurement is fast, low-cost, and harmless to the human body. However, it is difficult to measure micron-level coatings, and a coupling agent is required during the test process. X-ray thickness measurement can more intuitively display thickness images and can perform non-contact high-precision measurements, but it requires a protective source, is inconvenient to carry, and is difficult to measure thinner coatings. Metallographic microscope thickness measurement has the characteristics of high precision and good reproducibility, but this method is a destructive measurement method, and the sample preparation process of the test block requires precision, is relatively expensive, and is relatively complicated to operate. Eddy current thickness measurement is a commonly used method based on the principle of electromagnetic induction, but traditional eddy current thickness measurement sensors have high requirements on the shape of the component being inspected. They cannot achieve adaptive full contact measurement for the complex curved surfaces of aircraft, and are not suitable for large-scale on-site inspections. Summary of the Invention

[0004] The purpose of the present invention is to provide a complex curved surface automatic posture correction eddy current coating thickness measurement sensor with strong anti-interference ability, high detection efficiency and strong adaptability.

[0005] In order to achieve the above-mentioned objectives, the present invention adopts the following technical solutions: a complex curved surface automatic posture correction eddy current coating thickness measurement sensor, the measurement sensor including a spring-pressing mechanism, a spring return cylinder, and a posture adjustment mechanism; the spring-pressing mechanism is placed in the spring return cylinder and serves as the piston of the spring return cylinder. When compressed gas enters the spring return cylinder, the spring-pressing mechanism extends the spring return cylinder under the action of the gas pressure to complete the measurement of the coating thickness of the surface of the workpiece being inspected; the posture adjustment mechanism is used to adjust the state between the spring return cylinder and the side surface to complete the overall posture adjustment and correction of the measurement sensor.

[0006] Preferably, the posture adjustment mechanism includes a pressure sensor and a spherical hinge; the pressure sensor is installed at the bottom of the spring return cylinder through a support frame, and there are multiple pressure sensors, which are circumferentially arrayed in the direction of the main axis of the spring return cylinder and are used to transmit electrical signals to the circuit monitoring equipment. When the main axis direction of the measuring sensor is perpendicular to the surface to be measured of the workpiece to be inspected, the spring return cylinder works, thereby pushing the spring-pressing mechanism to fall and contact the surface to be measured for measurement; the spherical hinge is installed on the top of the spring return cylinder and can achieve 360° directional freedom of rotation. The other end is connected to the clamping device, and the orientation of the measuring sensor is adjusted under the action of the clamping device.

[0007] Preferably, the number of pressure sensors is 3, the lower end of which is a movable hemispherical conductor, the two upper terminals are connected to the positive and negative electrodes, and an open-circuit wire column is built in; when the pressure sensor presses down on the test surface of the workpiece to be tested, the hemispherical conductor rises, forming a closed path inside, and the electrical signal is transmitted to the circuit monitoring equipment, and the circuit monitoring equipment controls the clamping device.

[0008] Preferably, the support frame is used to clamp the pressure sensor to form a circumferential array state, connect the main axis of the measuring sensor, and make it always perpendicular to the plane direction of the pressure sensor.

[0009] Preferably, the spring-pressing mechanism includes a detection coil, a telescopic sleeve, a spring and an end cover; the detection coil is arranged at the end of the telescopic sleeve, and is used to induce an eddy current field on the surface of the inspected workpiece. Through the amplitude-thickness calibration algorithm, the detection coil picks up the coating thickness signal on the surface of the inspected workpiece and converts it into a corresponding thickness value, which is sent to the host computer for real-time display through the signal conditioning module and the A / D conversion module; the other end of the telescopic sleeve is connected to the end cover through a spring; and the reciprocating motion of the telescopic sleeve is completed by the compression and rebound of the spring.

[0010] Preferably, a boss structure extends outwardly from the cylindrical outer surface of the telescopic sleeve to serve as a medium for the spring thrust during the compression process.

[0011] Preferably, there are two detection coils, which are arranged one above the other.

[0012] Preferably, a hole is provided at the lower end of the end cover to provide space for the reciprocating motion of the telescopic sleeve and to serve as a supporting medium for the spring to complete the repeated compression motion of the spring.

[0013] Preferably, the springing mechanism further includes a springing sleeve, the upper end of which is connected to the end cover, providing a movable space for the reciprocating motion of the telescopic sleeve and constraining the telescopic sleeve to maintain axial motion.

[0014] Working Principle: The spring-pressing mechanism is used, and the cylinder piston pushes the measuring sensor to perform point-touch discrete measurement, ensuring that the measuring sensor exerts a constant pushing force on the coating during each measurement; the automatic posture adjustment part of the measuring sensor uses a combination of a pressure sensor and a spherical hinge to achieve adjustment of the normal vector angle under complex curved surfaces, ensuring the vertical measurement of the sensor, thereby improving the measurement efficiency and accuracy of the sensor.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] 1. Ensure that the measuring sensor produces a constant pushing force on the coating every time it measures;

[0017] 2. It ensures that the measuring sensor measures vertically, while improving the measuring efficiency and accuracy of the measuring sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A three-dimensional schematic diagram of the structure of an embodiment of the present invention;

[0019] Figure 2 Schematic diagram of the three-dimensional structure of the eddy current coating thickness measurement sensor part (spring-pressing mechanism) in an embodiment of the present invention;

[0020] Figure 3 Schematic diagram of the three-dimensional structure of the automatic attitude adjustment part (attitude adjustment mechanism) of the sensor in an embodiment of the present invention;

[0021] Figure 4 A schematic diagram of the three-dimensional structure of a pressure sensor in an embodiment of the present invention;

[0022] Figure 5 A schematic diagram of a signal transmission route according to an embodiment of the present invention;

[0023] Among them 1-5, 1. Two detection coils; 2. Telescopic sleeve 2; 3. Spring; 4. Spring-pressing sleeve; 5. End cover; 6. Pressure sensor; 7. Support frame; 8. Spring return cylinder; 9. Spherical hinge; 10. Movable hemispherical conductor; 11. Terminal block 11; 12. Signal conditioning module; 13. A / D conversion module; 14. Host computer. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below in conjunction with specific embodiments. The embodiments described below are exemplary and are only used to explain the present invention, and are not to be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications shall be followed.

[0025] The following is combined with Figure 1-5The present invention is further described in detail: a complex curved surface automatic posture correction eddy current coating thickness measurement sensor, including an eddy current coating thickness measurement sensor part (spring pressure mechanism), a spring return cylinder, a sensor automatic posture adjustment part (posture adjustment mechanism) and a host computer 14; the spring pressure mechanism serves as the piston of the spring return cylinder 8, which includes two detection coils 1, a telescopic sleeve 2, a spring 3, a spring pressure sleeve 4 and an end cover 5; the posture adjustment mechanism includes three closed trigger pressure sensors 6, three support frames 7 and a spherical hinge 9; as shown Figure 4 As shown, the lower end of the pressure sensor 6 is a movable hemispherical conductor 10, the two upper terminals 11 are connected to the positive and negative electrodes, and an open-circuit wire column is built in; the host computer 14 includes a signal conditioning module 12 and an A / D conversion module 13.

[0026] The specific structure is:

[0027] The detection coil 1 is built into the telescopic cylinder 2, the telescopic sleeve 2 is built into the spring-pressing sleeve 4, and is connected to the end cover 5 through the spring 3. The spring return cylinder 8 is connected to the closing trigger pressure sensor 6 through the support frame 7. The spherical hinge 9 connects the spring return cylinder 8 and the clamping device. The eddy current coating thickness measurement sensor is partially built into the spring return cylinder 8.

[0028] Two detection coils 1 are set at the end of the telescopic sleeve 2 to induce an eddy current field on the surface of the workpiece to be inspected. Through the amplitude-thickness calibration algorithm, the detection coils pick up the workpiece surface coating thickness signal and convert it into the corresponding thickness value. After passing through the signal conditioning module 12 and the A / D conversion module 13, it is sent to the host computer 14 for real-time display, storage, analysis of the measurement results and generation of report statistics;

[0029] The telescopic sleeve 2 is used to support and protect the detection coil 1. The cylindrical shape is extended with a boss structure. The boss structure serves as a medium for the spring thrust during the compression process to complete the repeated telescopic movement of the detection coil.

[0030] The spring 3 connects the telescopic sleeve 2 and the end cover 5. The reciprocating motion of the telescopic sleeve is completed by the compression and rebound of the spring 3. On the other hand, due to the fixed compression length of the spring 3, the telescopic sleeve is given a constant thrust, ensuring that the detection state is the same each time.

[0031] The spring sleeve 4 is connected to the lower end of the end cover 5, serving as the main support for the sensor detection part, providing space for the telescopic sleeve 2 to reciprocate, and constraining the telescopic sleeve to maintain radial movement;

[0032] The end cap 5 has a suitable hole to provide space for the reciprocating motion of the telescopic sleeve 2 and serves as a supporting medium for the spring 3 to complete the repeated compression motion of the spring 3;

[0033] Three closed-loop trigger pressure sensors 6 are arrayed circumferentially along the main axis of the measuring sensor. Each of these closed-loop trigger pressure sensors 6 features a movable hemispherical conductor 10 at its lower end, two upper terminals 11 for connecting positive and negative electrodes, and a built-in open-circuit wire stud. When the pressure sensors 6 press down on the surface of the test piece, the movable hemispherical conductor 10 rises, forming a closed path within the pressure sensors 6. The electrical signal from the pressure sensors 6 is transmitted to the circuit monitoring equipment. When all three pressure sensors 6 generate a trigger signal, the entire sensor main axis becomes perpendicular to the test surface, and the spring-return cylinder 8 activates, pushing the eddy current coating thickness measurement sensor down to contact the test surface for measurement.

[0034] The three support frames 7 are used to clamp the closure trigger pressure sensor 6 to form a circumferential array state, connect the sensor main axis so that it is always perpendicular to the plane direction of the three points (closure trigger pressure sensor), and improve the overall stability of the sensor;

[0035] When compressed gas enters the air inlet of the spring-return cylinder 8, the spring mechanism (piston) compresses the spring under the action of the gas pressure and moves in the opposite direction. When the compressed gas is no longer entering, the piston returns to its original position under the action of the spring force. After the spring-return cylinder 8 receives the trigger signal from the three pressure sensors, the piston pushes the eddy current coating thickness measurement sensor to the specified position to contact the surface to be measured for coating thickness measurement;

[0036] The spherical hinge 9 connects the overall eddy current coating thickness measurement sensor and the clamping device. The spherical hinge can achieve 360° directional rotation. When the sensor assembly is in a non-perpendicular state to the surface to be measured (non-normal direction), the clamping device detects the position of the untriggered pressure sensor through the triggering electrical signal, and pushes the sensor in that direction until the pressure sensor is triggered. Repeat the above steps until all three pressure sensors generate triggering electrical signals. At this time, the clamping device and the spherical hinge remain stationary, and the spring return cylinder pushes the eddy current coating thickness measurement sensor to perform measurement.

[0037] Figure 5 This is a schematic diagram of a signal transmission route according to an embodiment of the present invention, referring to Figure 5 As shown, the closed trigger pressure sensor 6 generates a trigger signal and transmits it to the trigger signal monitoring device, which feeds back the signal to the host computer to control the start and stop of the spring return cylinder 8; the detection coil 1 is used to induce an eddy current field on the surface of the workpiece to be inspected, and the coil pickup signal is inverted into the corresponding coating thickness value through the signal conditioning module 12 and the A / D conversion module 13 through the amplitude-thickness calibration algorithm, and is sent to the host computer 14 for real-time display.

[0038] The above embodiments are exemplary and should not be construed as limiting the present invention. A person skilled in the art may change, modify, replace, and modify the above embodiments within the scope of the present invention. At the same time, a person skilled in the art may make changes in the specific implementation methods and application scope based on the ideas of this application.

Claims

1. A sensor for measuring the thickness of eddy current coatings with automatic attitude correction on complex curved surfaces, characterized by: The measuring sensor includes a spring-pressing mechanism, a spring return cylinder, and a posture adjustment mechanism; the spring-pressing mechanism is placed in the spring return cylinder and serves as a piston of the spring return cylinder. When compressed gas enters the spring return cylinder, the spring-pressing mechanism extends the spring return cylinder under the action of gas pressure to complete the measurement of the coating thickness of the surface of the workpiece being inspected; the posture adjustment mechanism is used to adjust the state between the spring return cylinder and the side surface to complete the overall posture adjustment and correction of the measuring sensor; The posture adjustment mechanism includes a pressure sensor and a spherical hinge. The pressure sensor is mounted on the bottom of the spring return cylinder via a support frame. Multiple pressure sensors are arranged circumferentially in an array along the main axis of the spring return cylinder and are used to transmit electrical signals to the circuit monitoring device. When the main axis of the measuring sensor is perpendicular to the surface of the workpiece to be tested, the spring return cylinder is activated, thereby pushing the spring-loaded mechanism down to contact the surface to be tested for measurement. The spherical hinge is mounted on the top of the spring return cylinder and can achieve 360° directional rotation. The other end is connected to a clamping device, and the clamping device adjusts the orientation of the measuring sensor. The spring-pressing mechanism includes a detection coil, a telescopic sleeve, a spring and an end cover; The detection coil is set at the end of the telescopic sleeve and is used to induce an eddy current field on the surface of the workpiece being inspected. Through the amplitude-thickness calibration algorithm, the detection coil picks up the coating thickness signal of the workpiece surface being inspected and converts it into the corresponding thickness value. After passing through the signal conditioning module and the A / D conversion module, it is sent to the host computer for real-time display; the other end of the telescopic sleeve is connected to the end cover through a spring; the reciprocating motion of the telescopic sleeve is completed by the compression and rebound of the spring.

2. The complex curved surface automatic posture correction eddy current coating thickness measurement sensor according to claim 1 is characterized by: There are three pressure sensors, each with a movable hemispherical conductor at the lower end, two upper terminals connected to positive and negative electrodes, and a built-in open-circuit wire column. When the pressure sensor presses down on the test surface of the workpiece, the hemispherical conductor rises, forming a closed path inside, and the electrical signal is transmitted to the circuit monitoring equipment, which controls the clamping device.

3. The complex curved surface automatic posture correction eddy current coating thickness measurement sensor according to claim 1 is characterized by: The support frame is used to clamp the pressure sensor to form a circumferential array state, connect the main axis of the measuring sensor, and make it always perpendicular to the plane direction of the pressure sensor.

4. The complex curved surface automatic posture correction eddy current coating thickness measurement sensor according to claim 1 is characterized by: A boss structure extends outwardly from the cylindrical outer surface of the telescopic sleeve and serves as a medium for the spring thrust during the compression process.

5. The complex curved surface automatic posture correction eddy current coating thickness measurement sensor according to claim 1 is characterized by: There are two detection coils, which are arranged one above the other.

6. The complex curved surface automatic posture correction eddy current coating thickness measurement sensor according to claim 1 is characterized by: A hole is provided at the lower end of the end cover to provide space for the reciprocating motion of the telescopic sleeve and serve as a supporting medium for the spring to complete the repeated compression motion of the spring.

7. The complex curved surface automatic posture correction eddy current coating thickness measurement sensor according to claim 1 is characterized by: The springing mechanism also includes a springing sleeve, the upper end of which is connected to the end cover, providing a movable space for the reciprocating motion of the telescopic sleeve and constraining the telescopic sleeve to maintain axial motion.

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