Wave-absorbing coating reflectivity in-situ measurement device and method for confined space

Abstract

The invention provides an in-situ measurement device and method for the reflectivity of a wave-absorbing coating in a confined space, and belongs to the technical field of material reflectivity testing. According to the measuring device, the special-shaped coaxial probe is used for testing, the requirement for the area of a testing area is small, and the testing frequency band is wide; meanwhile, the probe can be stably attached to the surface of the coating to be measured in a self-adaptive mode through the arrangement of the suction cup with the skirt edge, the universal connector, the multiple air holes and the like, and reflectivity measurement of the plane or curved coating which cannot be touched by hands in the limited space is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of material reflectivity testing, and particularly relates to an in-situ reflectivity measurement device and method for a wave-absorbing coating in a confined space. BACKGROUND

[0002] The wave-absorbing coating is convenient to apply and has good adaptability to special-shaped surfaces, and is one of the most commonly used wave-absorbing methods in stealth technology. The wave-absorbing performance of the wave-absorbing coating in the coated state will deteriorate due to the influence of the external environment and the service life. In-situ measurement of the wave-absorbing performance of the coated coating is an important means to evaluate the service performance of the coating.

[0003] The wave-absorbing performance of the coating is characterized by radar reflectivity. For in-situ measurement of radar reflectivity, existing in-situ measurement devices are mainly divided into two categories: antenna probes and waveguide probes. A miniaturized ultra-wideband antenna is proposed in the document "In Situ Measurement of Absorbing Properties of Materials Based on Near-Field Reflection Method", and a handheld microwave reflectivity broadband tester is developed based on the antenna, with a test frequency covering 2-18 GHz, and the test results have good consistency with the standard bow method. A handheld reflectivity tester based on a compact dielectric antenna probe is introduced in the document "Microwave Material Measurements Without Cables", which integrates a modular vector reflectometer and can realize single-sensor ultra-wideband measurement. In the patent "An instrument for in-situ measurement of reflectivity performance of wave-absorbing coating" with publication number CN102798639A, a microwave circuit is integrated on the waveguide probe, which converts the microwave signal into a digital signal on the spot, and then connects with the host computer through a long cable, avoiding the deterioration of the long cable on the quality of the microwave signal. In the patent "A handheld radar wave-absorbing coating reflectivity in-situ measurement instrument" with publication number CN205982130U, the signal processing terminal and the waveguide probe are integrated together in the handheld instrument, and a built-in battery is provided, which is convenient for single person to carry and work.

[0004] In existing in-situ reflectivity measurement devices, although the device based on the antenna probe can realize ultra-wideband testing, it requires a large test area; and the device based on the waveguide probe has a smaller requirement for the test area, but the test frequency band is narrower. In addition, the existing two types of testing devices integrate the testing probe, the microwave transceiver module, the control processing module and the power supply in one place, so that the overall size of the device is still large, and therefore the device is mainly used in open scenes with large test spaces. For wave-absorbing coatings coated in narrow or confined spaces, existing equipment is difficult to stretch into the interior for probe loading and testing. SUMMARY

[0005] In view of the problems in the background art, the purpose of the present application is to provide a wave-absorbing coating reflectivity in-situ measurement device and method for a limited space; the measurement device uses a special-shaped coaxial probe for testing, which not only has a smaller requirement for the test area, but also has a wider test frequency band; at the same time, through the setting of a skirted suction cup, a universal connector, and multiple air holes, the probe can be stably attached to the surface of the coating to be measured, and the reflectivity of the plane or curved surface coating in the limited space that cannot be touched by hand is measured.

[0006] To achieve the above purpose, the technical scheme of the present application is as follows:

[0007] A wave-absorbing coating reflectivity in-situ measurement device for a limited space, comprising a skirted test probe, a universal connector, an endoscopic camera, a directional coupler, a support part, and a handheld operation platform;

[0008] The skirted test probe comprises a skirted suction cup, a special-shaped coaxial probe, and an air suction cavity; the skirted suction cup is composed of a cylindrical bellows and a funnel-shaped skirt, the funnel-shaped skirt is in contact with the surface of the wave-absorbing coating to be measured and forms a closed space; the special-shaped coaxial probe is arranged in the cylindrical bellows and comprises an inner conductor and an outer conductor, the inner wall of the outer conductor and the inner conductor are both composed of two upper and lower sections connected in sequence; the upper section is a circular truncated cone that expands radially from top to bottom, and the lower section is a cylinder; the top of the upper section of the inner conductor is fixedly connected with an SMA joint; a plurality of through holes are arranged on the outer conductor; one end of the cylindrical bellows and one end of the air suction cavity are fixedly arranged on the surface of the outer conductor of the special-shaped coaxial probe, and the through holes serve as air holes to connect the air suction cavity and the space in the skirted suction cup;

[0009] The SMA joint is connected with the input end of the directional coupler through a radio frequency cable; the other end of the air suction cavity is connected with an air suction pump through an air pipe;

[0010] The universal connector comprises a lower ring and an upper ring, which are movably connected; the lower ring is movably connected with the outer surface of the air suction cavity, and the upper ring is fixedly connected with one end of the support part, so that the skirted test probe has a certain amount of movement in the up-down, left-right, and front-back directions; the other end of the support part is fixedly connected with the handheld operation platform, which is used to provide support for the skirted test probe;

[0011] The directional coupler is fixedly connected with the handheld operation platform; the handheld operation platform is integrated with a microwave transceiver module, a control processing module and a suction pump; the microwave transceiver module is used for providing a microwave signal source, the transmitting port of the microwave transceiver module is connected with the output end of the directional coupler, and the receiving port of the microwave transceiver module is connected with the coupling end of the directional coupler; the directional coupler is used for separating incident signals and reflected signals; the suction pump is used for pumping the air in the suction cavity, so that the internal air pressure of the suction cavity is reduced, and the air in the air suction disc with a skirt is pumped through the air hole; the control processing module is used for processing the incident signals and the reflected signals transmitted by the microwave transceiver module; the endoscopic camera is arranged near the test probe with a skirt through an endoscopic camera cable, the endoscopic camera has the functions of illumination and image shooting, can be freely rotated, and is controlled by the handheld operation platform to shoot the test area, so that the test area is positioned.

[0012] Further, the air suction disc with a skirt is made of a flexible material, the funnel-shaped skirt structure of the air suction disc with a skirt is convenient for closely adhering to the surface of the wave-absorbing coating to be measured, the cylindrical bellows structure reduces the longitudinal resistance during the working of the air suction disc, reduces the negative pressure requirement of the air pumping device, and facilitates the flexible and light adhesion of the special-shaped coaxial probe to the surface of the wave-absorbing coating to be measured.

[0013] Further, the inner conductor and the outer conductor can be filled with a medium, preferably polytetrafluoroethylene.

[0014] Further, the support part is preferably a metal hose.

[0015] Further, the wave-absorbing coating reflectivity in-situ measurement device further comprises an extension rod, one end of the extension rod is fixedly connected with the support part, and the other end of the extension rod is fixed on the handheld operation platform, so as to expand the detection range; the extension rod is hollow inside and carries an air pipe, a radio frequency cable and an endoscopic camera cable.

[0016] Further, the extension rod is made of a low-density high-strength material, such as a carbon fiber tube, and the length of the extension rod is determined according to the position distance of the coating to be measured.

[0017] Further, the wave-absorbing coating reflectivity in-situ measurement device further comprises a channel fixer, the channel fixer is used for folding the air pipe, the radio frequency cable and the metal hose, so as to adjust and fix the structure of the test device and improve the test stability.

[0018] Further, the length of the circular truncated cone section of the inner conductor of the probe and the diameter of the upper and lower end faces are designed to have a characteristic impedance gradient function, so that the characteristic impedance of the end of the probe is closer to the wave impedance of the wave-absorbing coating to be measured, the echo loss in the probe is reduced, and the dynamic range of the probe reflection measurement can be effectively improved.

[0019] The application also provides a test method for the wave-absorbing coating reflectivity in-situ measurement device in a limited space as follows:

[0020] Step 1: set the test frequency band, frequency point number and other test parameters on the handheld operation platform;

[0021] Step 2: the test probe with a skirt is close to and towards the metal calibration plate, and then the air suction pump is started, so that the special-shaped coaxial probe is adsorbed and closely attached to the metal calibration plate, and the reflectivity Γ0 is recorded after the curve is stable;

[0022] Step 3: according to the position of the target area of the coating to be measured in the restricted space, the support part is manually adjusted, so that the test probe with a skirt is towards the target area; the endoscopic camera is started, the test probe with a skirt is stretched into the restricted space and slowly close to the target area, and then the air suction pump is started, so that the special-shaped coaxial probe is self-adaptively and stably attached to the surface of the target area, and the reflectivity Γ1 is recorded after the curve is stable;

[0023] Step 4: the reflectivity Γ of the coating to be measured is calculated according to the test data test ,

[0024]

[0025] As described above, due to the adoption of the above technical scheme, the present application has the following beneficial effects:

[0026] Although the coaxial probe can realize the test in the restricted space, it will face the problem of how to make the coaxial probe stably and closely attached to the surface of the coating to be measured. The measuring device provided by the present application is combined by the unique test probe with a skirt, the air path structure and the universal connector, and the air suction device is used to reduce the air pressure in the suction cup, so as to provide suction force for the test probe with a skirt under the condition of no external pressure, so that the test probe in the suction cup is self-adaptively and stably attached to the surface of the coating to be measured, that is, the probe is closely attached to the surface of the coating to be measured by atmospheric pressure.

[0027] The restricted space cannot be directly contacted by hand, and sometimes the line of sight cannot be directly observed. The combination of the support part and the universal connector enables the probe to adjust the angle, and the endoscopic camera provides the visual positioning function, so as to accurately attach the coating to be measured with an unknown surface shape in the restricted space. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 It is a structural schematic view of the in-situ measuring device for the reflectivity of the wave-absorbing coating of the present application;

[0029] Figure 2 It is a structural schematic view of the test probe with a skirt in the in-situ measuring device for the reflectivity of the wave-absorbing coating of the present application;

[0030] Figure 3 It is an installation schematic view of the universal connector in the in-situ measuring device for the reflectivity of the wave-absorbing coating of the present application.

[0031] Figure 4A physical diagram of the in-situ measurement device for reflectivity of wave-absorbing coating of the present application.

[0032] Figure 5 A test data diagram of the embodiment 1 of the present application and the bow method for different thicknesses of the coating to be measured.

[0033] The figure shows that the in-situ measurement device for reflectivity of wave-absorbing coating of the present application includes a skirted test probe 1, a universal connector 2, a channel fixer 3, an endoscopic camera 4, a directional coupler 5, an extension rod 6, and a handheld operating platform 7. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described in further detail below in combination with embodiments and drawings.

[0035] The in-situ measurement device for reflectivity of wave-absorbing coating of the present application for a confined space has a schematic diagram as shown in the figure, which includes a skirted test probe 1, a universal connector 2, a channel fixer 3, an endoscopic camera 4, a directional coupler 5, an extension rod 6, and a handheld operating platform 7. Figure 1

[0036] The figure shows that the structure of the skirted test probe includes a skirted suction cup 11, a special coaxial probe 12, and a suction cavity 13. Figure 2

[0037] ​​The skirted chuck is composed of a cylindrical bellows and a funnel-shaped skirt, and is made of flexible material. The funnel-shaped skirt structure facilitates close adhesion to the surface of the wave-absorbing coating to be measured, forming a closed space. The cylindrical bellows structure reduces the longitudinal resistance when the chuck is working, reduces the negative pressure requirement of the air extraction device, and facilitates the flexible and light adhesion of the special-shaped coaxial probe to the surface of the coating to be measured. The diameter of the bottom of the skirted chuck is 4 cm. The special-shaped coaxial probe is arranged in the cylindrical bellows and includes an inner conductor and an outer conductor, and has a gradual segmented structure. The characteristic impedance gradually changes from 50Ω at the feeding port to 72Ω at the opening, so as to reduce the echo loss in the probe and improve the dynamic range of the reflectivity test. The inner wall of the outer conductor and the inner conductor are each composed of two upper and lower segments connected in sequence. The upper segment is a circular truncated cone, which gradually expands radially from top to bottom. The lower segment is a cylinder. The top of the upper segment of the inner conductor is fixedly connected with an SMA joint. A plurality of through holes are arranged on the outer conductor, which are used as air holes 121 to connect the air extraction cavity and the space in the skirted chuck. One end of the cylindrical bellows and one end of the air extraction cavity are fixedly arranged on the surface of the outer conductor of the special-shaped coaxial probe. Specifically, the outer surface of the outer conductor of the special-shaped coaxial probe has external threads 122, and the top of the skirted chuck can be pressed tightly by the bottom of the air extraction cavity and the special-shaped coaxial probe through the flange 123. The SMA joint is connected with the input end of the directional coupler through the radio frequency cable 14 passing through the top of the air extraction cavity. The air extraction cavity is connected with the air extraction pump through the air pipe 15 at the top. The mounting diagram of the universal connector is shown in Figure 3 The lower ring is movably connected with the outer surface of the air extraction cavity, and the upper ring is fixedly connected with one end of the support part. The support part is preferably two metal flexible pipes 16, which can freely move the skirted test probe up and down by 0.5 cm and rotate by ±15° in the front-back and left-right directions. The metal flexible pipe can be manually bent to adjust the initial spatial position of the skirted test probe, so that the movable angle range of the test probe covers the normal direction of the curved surface of the coating to be measured. The length of the metal flexible pipe is 20 cm, and the diameter is 4 mm, which can bear at least 100 g without deformation.

[0038] The top end of the extension rod is fixedly connected with the other end of the metal flexible pipe, and the top end is provided with a directional coupler. The bottom end is fixed on a handheld operation table, and the inside is hollow and carries an air pipe, a radio frequency cable and an endoscope camera cable. The handheld operation table is integrated with a microwave transceiver module, a control processing module and an air extraction pump. The microwave transceiver module is used to provide a microwave signal source, and the transmitting port is connected with the output end of the directional coupler, and the receiving port is connected with the coupling end of the directional coupler. The directional coupler is used to separate the incident signal and the reflected signal. The directivity of the directional coupler is greater than 15 dB in the frequency band of 2-18 GHz. Therefore, the whole measuring device can be applied to the bandwidth of 2-18 GHz.

[0039] The air suction pump is used for air suction of the air suction cavity to reduce the internal air pressure, and the air in the skirted chuck is extracted through the air hole; the control processing module is used for processing the incident signal and the reflected signal transmitted by the microwave transceiver module; the endoscopic camera is arranged near the skirted test probe through an endoscopic camera cable, and the endoscopic camera has an illumination and a camera function and can be freely rotated, and the hand-held operation platform is used to control the endoscopic camera to shoot the test area, so that the test area is positioned.

[0040] The channel fixer can fold the trachea, the radio frequency cable and the metal hose, facilitate adjustment and solidification of the test device structure, and improve test stability; the extension rod is made of carbon fiber material, has a length of 1.5 m and an inner diameter of 3 cm.

[0041] The physical diagram of the device is shown in Figure 4 .

[0042] Embodiment 1

[0043] A use method of an in-situ measurement device for reflectivity of a wave-absorbing coating in a limited space, comprising the following steps:

[0044] Step 1: setting parameters such as a test frequency band and a frequency point number on the hand-held operation platform;

[0045] Step 2: approaching the skirted test probe to the metal calibration plate and then turning on the air suction pump to make the test probe adsorb and tightly adhere to the metal calibration plate, and recording the reflectivity Γ0 when the curve is stable;

[0046] Step 3: manually adjusting the metal hose to make the skirted test probe face the target area of the coating to be measured according to the position of the coating to be measured in the limited space; turning on the endoscopic camera, extending the skirted test probe into the limited space and slowly approaching the target area, and then turning on the air suction pump to make the test probe self-adaptively and stably adhere to the surface of the target area, and recording the reflectivity Γ1 when the curve is stable;

[0047] Step 4: calculating the reflectivity Γ of the coating to be measured according to the test data, and the process is as follows: test

[0048]

[0049] Wherein, Γ0 and Γ1 are linear values.

[0050] In this embodiment, a typical commercial wave-absorbing coating is tested, and a conventional arc-shaped method is used to test the same wave-absorbing material, and the test data results are shown in Figure 5 From the figure, it can be seen that the test results of the device of the present application and the test results of the arc-shaped method are relatively consistent, which indicates that the test device of the present application can be used for testing, and the test results have reliability.

[0051] ​The above merely provides the specific implementation of the present application, any feature disclosed in the specification can be replaced by other equivalent or similar purpose alternative features unless specifically described, and all features disclosed or all steps in the method or process can be combined in any manner except for mutually exclusive features and / or steps.

Claims

1. An in-situ measurement device for reflectivity of a wave-absorbing coating for a confined space, characterized in that, The device comprises a skirted test probe, a universal connector, an endoscopic camera, a directional coupler, a support part and a handheld operating platform. The skirted test probe comprises a skirted chuck, a special-shaped coaxial probe and an air suction cavity; the skirted chuck is composed of a cylindrical bellows and a funnel-shaped skirt, the funnel-shaped skirt is in contact with the surface of the wave-absorbing coating to be measured and forms a closed space; the special-shaped coaxial probe is arranged in the cylindrical bellows and comprises an inner conductor and an outer conductor, the inner wall of the outer conductor and the inner conductor are both composed of two sections connected in sequence, the upper section is a circular truncated cone which expands radially from top to bottom, and the lower section is a cylinder; the top of the upper section of the inner conductor is fixedly connected with an SMA joint; a plurality of through holes are arranged on the outer conductor; one end of the cylindrical bellows and one end of the air suction cavity are fixedly arranged on the surface of the outer conductor of the special-shaped coaxial probe, and the through holes serve as air holes to connect the air suction cavity and the space in the skirted chuck; The SMA joint is connected with the input end of the directional coupler through a radio frequency cable; the other end of the air suction cavity is connected with an air suction pump through an air pipe; The universal connector comprises a lower ring and an upper ring, and the two are movably connected; the lower ring is movably connected with the outer surface of the air suction cavity, and the upper ring is fixedly connected with one end of the support part, so that the skirted test probe has a certain amount of movement in the up-down, left-right and front-back directions; the other end of the support part is fixedly connected with the handheld operating platform, which provides support for the skirted test probe; The directional coupler is fixedly connected with the handheld operating platform; the handheld operating platform is integrated with a microwave transceiver module, a control processing module and an air suction pump; the microwave transceiver module is used to provide a microwave signal source, and the transmitting port thereof is connected with the output end of the directional coupler, and the receiving port thereof is connected with the coupling end of the directional coupler; The directional coupler is used to separate the incident signal and the reflected signal; The air suction pump is used to pump air out of the air suction cavity and the air holes to pump air out of the skirted chuck; the control processing module is used to process the incident signal and the reflected signal transmitted by the microwave transceiver module; The endoscopic camera is arranged near the skirted test probe through an endoscopic camera cable, has the functions of illumination and image capturing, and can be freely rotated; the handheld operating platform is used to control the endoscopic camera to capture the test area, which is convenient for positioning the test area.

2. The wave-absorbing coating reflectivity in-situ measurement device for confined spaces of claim 1, wherein, The skirted chuck is made of flexible material, the funnel-shaped skirt structure thereof can be closely attached to the surface of the wave-absorbing coating to be measured, the cylindrical bellows structure thereof can reduce the longitudinal resistance during the operation of the chuck, reduce the negative pressure requirement of the air pumping device, and facilitate the flexible and light attachment of the special-shaped coaxial probe to the surface of the wave-absorbing coating to be measured.

3. The wave-absorbing coating reflectivity in-situ measurement device for confined spaces of claim 1, wherein, The inner conductor and the outer conductor are filled with a medium.

4. The wave-absorbing coating reflectivity in-situ measurement device for confined spaces of claim 3, wherein, The medium is polytetrafluoroethylene.

5. The wave-absorbing coating reflectivity in-situ measurement device for confined spaces of claim 1, wherein, The support part is a metal hose.

6. The wave-absorbing coating reflectivity in-situ measurement device for confined spaces of claim 1, wherein, The wave-absorbing coating reflectivity in-situ measurement device further comprises an extension rod, one end of the extension rod is fixedly connected with the support part, and the other end of the extension rod is fixed on the handheld operating platform, which is used to expand the detection range; the extension rod is hollow and carries an air pipe, a radio frequency cable and an endoscopic camera cable.

7. The wave-absorbing coating reflectivity in-situ measurement device for confined spaces of claim 6, wherein, The extension rod is made of low-density high-strength material, and the length thereof is determined according to the position distance of the coating to be measured.

8. The wave-absorbing coating reflectivity in-situ measurement device for confined spaces of claim 1, wherein, The in-situ reflectivity measuring device of the wave-absorbing coating further comprises a channel fixer for folding the trachea, radio frequency cable and metal hose, facilitating adjustment and fixation of the testing device structure and improving testing stability.

9. The wave-absorbing coating reflectivity in-situ measurement device for confined spaces of claim 1, wherein, The length of the circular truncated cone section of the inner conductor of the probe and the diameter of the upper and lower end faces are designed to have a characteristic impedance gradient function, so that the characteristic impedance of the probe end is closer to the wave impedance of the wave-absorbing coating to be measured, the echo loss inside the probe is reduced, and the dynamic range of the probe reflection measurement is improved.

10. A method of testing a device for in-situ measurement of reflectivity of a wave- absorbing coating for confined spaces according to any one of claims 1-9, characterized in that, The method comprises the following steps: Step 1: setting test frequency band, frequency point number and other test parameters on the handheld operation platform; Step 2: placing the test probe with skirt close to and towards the metal calibration plate, then starting the air suction pump, so that the special-shaped coaxial probe is adsorbed and closely attached to the metal calibration plate, and the reflectivity Γ0 is recorded after the curve is stable; Step 3: manually adjusting the support part according to the target region position of the coating to be measured in the limited space, so that the test probe with skirt is towards the target region; starting the endoscopic camera, and then the test probe with skirt is slowly placed close to the target region inside the limited space, and the air suction pump is started, so that the special-shaped coaxial probe is self-adaptively and stably attached to the surface of the target region, and the reflectivity Γ1 is recorded after the curve is stable; Step 4: Calculate the reflectivity of the coating under test Γ from the test data test ,

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