Liquid film thickness calibration device and thickness calibration method thereof

Abstract

This invention proposes a liquid film thickness calibration device and method. The device includes a linear displacement stage, a sensor holding device, a water-immersion ultrasonic sensor, a coupling water tank, a force sensor, a displacement platform, a first angular displacement platform, and a second angular displacement platform. The sensor holding device is located above the coupling water tank, which has an opening at its bottom for sealing connection with the boss of a bearing standard test block. The displacement platform is located below the coupling water tank. The top surface of the upper moving plate of the displacement platform is used to place the force sensor to abut against the groove of the shaft standard test block. The first and second angular displacement platforms are located below the displacement platform to adjust the inclination angle of the upper moving plate, thereby adjusting the parallelism of the shaft standard test block relative to the bearing standard test block. This invention solves the problem of high-precision parallelism adjustment of the friction pair contact interface by real-time monitoring of the contact force reading and adjusting the angular displacement stage.

Description

Technical Field

[0001] This invention relates to the field of measuring device technology, and in particular to a liquid film thickness calibration device and its thickness calibration method. Background Technology

[0002] Ships are crucial carriers for my country's transportation, marine development, and defense of maritime rights. As a core component of the ship's propulsion system, the stern bearing bears the critical task of supporting the weight of the propeller and stern shaft. During service, it faces complex and harsh operating conditions: under the cantilevered load of the propeller, the local pressure on the bearing can reach more than five times the average specific pressure; simultaneously, it must withstand periodic pulse loads and impacts from the propeller and hull; for water-lubricated stern bearings, the minimum rotational speed may be as low as 10 r / min, making it difficult to form an effective hydrodynamic lubricating oil film; furthermore, impurities such as silt and marine organisms in the aquatic environment can easily penetrate the bearing's working surface, exacerbating the risk of wear at the friction interface.

[0003] The lubricating water film formed between the relatively moving surfaces of a bearing friction pair by the hydrodynamic effect is crucial for preventing direct surface contact and avoiding problems such as accelerated wear, frictional noise, and shaft vibration caused by poor lubrication. Therefore, the thickness of the lubricating film is a core parameter reflecting the bearing's lubrication condition and transmission efficiency, making its precise measurement essential.

[0004] However, since ship shafting systems are typically enclosed structures, existing oil film thickness calibration methods (such as ultrasonic and optical methods) lack reliable benchmarks for measurement. Therefore, there is an urgent need to develop a calibration test bench specifically for calibrating bearing oil film thickness calibration methods. Current calibration devices (such as static wedge film calibration devices, extrusion devices, and clearance adjustment devices) all have significant limitations: First, the measurement accuracy of static wedge film calibration devices and clearance adjustment devices heavily relies on machining accuracy and cannot achieve dynamic adjustment of film thickness; second, extrusion devices are limited by the length of the extrusion plate and the mass of the droplets, resulting in a limited calibration range, significant human measurement errors, and an inability to adjust the parallelism between two test blocks. To balance measurement accuracy and flexibility, and to provide an effective theoretical verification method for precise measurement of ship bearing lubrication film thickness, there is an urgent need to develop a high-precision liquid film thickness calibration device. Summary of the Invention

[0005] The main objective of this invention is to provide a liquid film thickness calibration device and a thickness calibration method, which aims to adjust the parallelism between two test blocks with high precision.

[0006] To achieve the above objectives, the present invention provides a liquid film thickness calibration device, comprising a linear displacement stage, a sensor holding device, a water immersion ultrasonic sensor, a coupling water tank, a force sensor, a displacement platform, a first angular displacement platform, and a second angular displacement platform, wherein... The sensor holding device and the coupling water tank frame are both located on one side of the linear displacement stage. The sensor holding device is located above the coupling water tank and is used to support the water immersion ultrasonic sensor. The bottom of the coupling water tank has an opening to seal and connect with the boss of the bearing standard test block. The displacement platform is located below the coupling water tank. The top surface of the upper moving plate of the displacement platform is used to place the force sensor to abut against the groove of the shaft standard test block. Below the displacement platform, a first angular displacement platform and a second angular displacement platform are arranged in sequence to drive the overall movement of the displacement platform to adjust the inclination angle of the upper moving plate and thus adjust the parallelism of the shaft standard test block relative to the bearing standard test block.

[0007] Preferably, the water immersion ultrasonic sensor is electrically connected in sequence to an ultrasonic pulse transceiver, a signal oscilloscope, and a host computer.

[0008] Preferably, the force sensor is electrically connected in sequence to a pressure indicator and a power module, and the displacement platform is electrically connected to a room temperature piezoelectric cascade controller to control the displacement distance and displacement direction of the upper moving plate.

[0009] Preferably, the rotation axes of the first angular displacement platform and the second angular displacement platform are arranged perpendicularly.

[0010] Preferably, the sensor holding device is adjustable in height relative to the coupling water tank.

[0011] Preferably, the sensor holding device has a through hole, and a washer is embedded in the through hole. The water-immersed ultrasonic sensor is inserted into the washer in the through hole to be supported on the sensor holding device.

[0012] Preferably, a threaded hole is provided on the bottom surface of the outer wall of the coupling water tank for fasteners to pass through. The fasteners pass through the through hole of the shaft standard test block or bearing standard test block and the threaded hole of the coupling water tank, thereby fixing the shaft standard test block or bearing standard test block to the coupling water tank.

[0013] Preferably, the displacement platform is a piezoelectric displacement platform with a stepping accuracy at the nm level and a displacement stroke at the output end at the mm level.

[0014] The present invention also proposes a thickness calibration method based on the above-described liquid film thickness calibration device, comprising the following steps: Bearing standard test blocks and shaft standard test blocks are installed below the coupling water tank. With the coupling water tank filled with water, the sound velocity of the bearing standard test blocks and shaft standard test blocks is obtained by collecting the reflected echoes from the upper and lower interfaces of the bearing standard test blocks and shaft standard test blocks respectively. Standard bearing test blocks and standard shaft test blocks are installed below the coupling water tank, and water is dripped between the standard bearing test blocks and the standard shaft test blocks. The displacement platform is controlled to move downward, and the sound velocity of the water is determined by collecting the reflected echoes of the test blocks before and after the displacement platform moves. Remove the water between the bearing standard test block and the shaft standard test block, adjust the liquid film thickness calibration device to the initial state, and adjust the first angular displacement platform and the second angular displacement platform until the shaft standard test block is parallel to the bearing standard test block. Then, control the displacement platform to move down, collect the signal of the bearing standard test block-air interface as a reference signal, and perform zero-padding Fourier transform on the reference signal to obtain the amplitude and phase information of the reference signal. Water was dripped between the bearing standard test block and the shaft standard test block. The initial film thickness was calculated using the ultrasonic resonance method. The displacement platform was raised in a specific step size to set water films of different thicknesses. After each film thickness adjustment, the corresponding water film reflection echo signal was collected. The accuracy of the thickness measurement method is evaluated based on the amplitude and phase information of the water film reflected echo signal and the reference signal.

[0015] Preferably, the step of evaluating the accuracy of the thickness measurement method based on the amplitude and phase information of the water film reflection echo signal and the reference signal specifically includes: performing zero-padding Fourier transform on the acquired water film reflection echo signal in the host computer to obtain the corresponding amplitude and phase information, dividing and subtracting the amplitude and phase of the reference signal respectively, calculating the reflection coefficient, obtaining the calculated film thickness using the film thickness algorithm through the reflection coefficient, comparing the calculated film thickness with the theoretical film thickness obtained based on the displacement platform, and evaluating the accuracy of the thickness measurement method.

[0016] The liquid film thickness calibration device proposed in this invention has the following beneficial effects: 1. By integrating the first angular displacement platform and the second angular displacement platform, and with the force sensor placed between the shaft standard test block and the displacement platform, the parallelism of the friction pair interface formed by the shaft standard test block and the bearing standard test block can be controlled. 2. This liquid film thickness calibration device has high flexibility and can adapt to the precise fit of the friction interface under different test block tilt angle adjustment requirements; 3. This liquid film thickness calibration device adopts a modular design concept, which supports the rapid replacement of key functional components, including friction pair test blocks, sensors, drive units, etc. It is convenient to flexibly configure experimental adjustments according to different bearing testing requirements (such as material type, friction conditions, environmental parameters, etc.), which improves the versatility and adaptability of the device, while significantly reducing maintenance costs and simplifying the functional upgrade process. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a preferred embodiment of the liquid film thickness calibration device of the present invention; Figure 2a This is a reflection echo diagram of the upper and lower interfaces of a bearing standard test block in a preferred embodiment of the liquid film thickness calibration device of the present invention; Figure 2bThis is a reflection echo diagram of the upper and lower interfaces of the standard test block in a preferred embodiment of the liquid film thickness calibration device of the present invention; Figure 2c The preferred embodiment of the liquid film thickness calibration device of the present invention shows the reflected echoes from the upper and lower interfaces of the water film before and after the displacement platform moves; Figure 3a This is a time-domain waveform diagram of the reference signal in a preferred embodiment of the liquid film thickness calibration device of the present invention; Figure 3b This is a diagram showing the amplitude information of the reference signal in a preferred embodiment of the liquid film thickness calibration device of the present invention; Figure 3c This is a phase information diagram of the reference signal in a preferred embodiment of the liquid film thickness calibration device of the present invention; Figure 4a This is a comparison diagram of the calculated film thickness and the theoretical film thickness in a preferred embodiment of the liquid film thickness calibration device of the present invention; Figure 4b This is a relative error diagram of a preferred embodiment of the liquid film thickness calibration device of the present invention; Figure 5 This is a schematic diagram of the bearing standard test block in the liquid film thickness calibration device of the present invention.

[0018] In the figure, 1-linear displacement stage, 2-sensor holding device, 3-water immersion ultrasonic sensor, 4-coupling water tank, 5-bearing standard test block, 51-bore, 52-through hole, 6-shaft standard test block, 7-force sensor, 8-displacement platform, 9-first angular displacement platform, 10-second angular displacement platform, 11-mounting frame, 12-piezoelectric cascade controller, 13-pressure indicator, 14-power module, 15-ultrasonic pulse transceiver, 16-signal oscilloscope, 17-host computer.

[0019] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0021] It should be noted that in the description of this invention, the terms "lateral," "longitudinal," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used solely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0022] This invention proposes a liquid film thickness calibration device.

[0023] Reference Figure 1 In this preferred embodiment, a liquid film thickness calibration device includes a linear displacement stage 1, a sensor holding device 2, a water immersion ultrasonic sensor 3, a coupling water tank 4, a force sensor 7 (using a miniature force sensor), a displacement platform 8, a first angular displacement platform 9, and a second angular displacement platform 10, wherein... The sensor holding device 2 and the coupling water tank 4 are both located on one side of the linear displacement stage 1. The sensor holding device 2 is located above the coupling water tank 4 and is used to support the water immersion ultrasonic sensor 3. The bottom end of the coupling water tank 4 has an opening to seal and connect with the boss of the bearing standard test block 5. The displacement platform 8 is located below the coupling water tank 4. The top surface of the upper moving plate of the displacement platform 8 is used to place the force sensor 7 to abut against the groove of the shaft standard test block 6. The first angular displacement platform 9 and the second angular displacement platform 10 are arranged in sequence below the displacement platform 8 to drive the overall movement of the displacement platform 8 to adjust the inclination angle of the upper moving plate and thus adjust the parallelism of the shaft standard test block 6 relative to the bearing standard test block 5.

[0024] like Figure 5 As shown, a boss 51 is provided on the top surface of the bearing standard test block 5 (the boss 51 is used to insert into the groove of the coupling water tank 4 to seal the groove). The bearing standard test block 5 is also provided with a through hole 52 for fasteners to pass through. The shaft standard test block 6 has a similar structure to the bearing standard test block 5, except that a groove is provided on the bottom surface of the shaft standard test block 6 for installing the force sensor 7.

[0025] Furthermore, the water immersion ultrasonic sensor 3 is electrically connected in sequence to an ultrasonic pulse transceiver 15 (connected to the water immersion ultrasonic sensor 3 via a BNC cable), a signal oscilloscope 16 (connected to the ultrasonic pulse transceiver 15 via a BNC cable), and a host computer 17 (connected to the signal oscilloscope 16 via a USB cable). The force sensor 7 is electrically connected in sequence to a pressure indicator 13 (connected to the force sensor 7 via a cable) and a power module 14. The displacement platform 8 is electrically connected to a piezoelectric cascade controller 12 (using a room temperature piezoelectric cascade controller) to control the displacement distance and direction of the upper moving plate. The pulse transceiver excites the sensor to emit ultrasonic waves by sending negative square waves. The signal oscilloscope 16 is connected via a USB cable to realize real-time display and acquisition of ultrasonic signals. The ultrasonic pulse transceiver 15 excites the sensor to emit ultrasonic waves by sending negative square waves. The power module 14 is connected to the pressure indicator 13 via a power cord to realize real-time pressure display.

[0026] Furthermore, in this embodiment, the rotation axes of the first angular displacement platform 9 and the second angular displacement platform 10 are arranged vertically.

[0027] By vertically setting the rotation axes of the first angular displacement platform 9 and the second angular displacement platform 10, and combining them, the final goal is to finely adjust the plane tilt angle of an object placed on them, thereby adjusting the parallelism of the shaft standard test block 6 relative to the bearing standard test block 5. The first angular displacement platform 9 is... α The shaft manual angular displacement platform, the second angular displacement platform 10 is β Manual angular displacement platform for shafts.

[0028] Furthermore, the installation height of the sensor holding device 2 relative to the coupling water tank 4 is adjustable. Specifically, the linear height of the sensor holding device 2 can be adjusted by rotating the micrometer of the linear displacement stage 1, thereby adjusting the installation height of the sensor holding device 2 relative to the coupling water tank 4. The sensor holding device 2 is connected to the linear displacement stage 1 by bolts.

[0029] In this embodiment, the sensor holding device 2 has a through hole, and a washer is embedded in the through hole. The water immersion ultrasonic sensor 3 is inserted into the washer in the through hole to be supported on the sensor holding device 2. The inner diameter of the washer is slightly smaller than the outer diameter of the water immersion ultrasonic sensor 3. The sensor focus is adjusted by slightly wiggling the water immersion ultrasonic sensor 3.

[0030] In this embodiment, a threaded hole is provided on the bottom surface of the outer wall of the coupling water tank 4 for fasteners to pass through. The fasteners pass through the through hole of the shaft standard test block 6 or the bearing standard test block 5 and the threaded hole of the coupling water tank 4, thereby fixing the shaft standard test block 6 or the bearing standard test block 5 to the coupling water tank 4.

[0031] Furthermore, the displacement platform 8 is a piezoelectric displacement platform with a step size in the nm range, a resolution in the nm range, and a stroke in the mm range. The piezoelectric displacement platform 8 is connected to the room-temperature piezoelectric cascade controller 12 via a cable interface. After the controller is powered on, it drives the piezoelectric displacement platform 8 to move up and down by sending an electrical signal to the displacement stage. The displacement platform 8 has a stroke of 5 mm, a resolution of 2 nm, and a minimum step size of 10 nm.

[0032] To address the problems of large measurement errors, small adjustment range, and limitations imposed by machining precision in traditional film thickness calibration devices, this embodiment employs a piezoelectric displacement platform 8 with a large stroke (5 mm), small step (10 nm), and high resolution (2 nm), effectively overcoming the aforementioned defects and significantly improving the film thickness adjustment range and calibration accuracy.

[0033] The bottom of the displacement platform 8 is connected to the first angular displacement platform 9 by bolts, and the bottom of the first angular displacement platform 9 is connected to the top surface of the second angular displacement platform 10 by bolts. By adjusting the angle of the first angular displacement platform 9 and the second angular displacement platform 10, the parallelism of the shaft standard test block 6 relative to the bearing standard test block 5 is adjusted.

[0034] A mounting frame 11, made of stainless steel, is installed below the second angular displacement platform 10. The mounting frame 11 includes a base plate and a side plate fixed to one side of the base plate. The top of the side plate is used to mount the linear displacement stage 1. The top surface of the base plate of the mounting frame 11 is flat. The base plate is bolted to the bottom surface of the second angular displacement platform 10. The linear displacement stage 1 is fixed to the side plate with fasteners (such as flathead bolts) to support the sensor holding device 2. The coupling water tank 4 is connected to the mounting frame 11 with hexagonal socket head cap screws.

[0035] The specific operation of this liquid film thickness calibration device is as follows.

[0036] 1. First, according to Figure 1 When installing the liquid film thickness calibration device as shown, do not install the shaft standard test block 6 first; then, fill the coupling water tank 4 with water and turn on the ultrasonic pulse transceiver 15 and signal oscilloscope 16; as shown Figure 2a As shown, reflected echoes from the upper and lower interfaces of bearing standard test block 5 are collected, and the path difference between the two reflected echoes is determined to calculate the sound velocity of bearing standard test block 5. Next, bearing standard test block 5 is disassembled, and shaft standard test block 6 is installed. Shaft standard test block 6 is sealed and installed below coupling water tank 4. Both sides of shaft standard test block 6 are connected to coupling water tank 4 using bolts. The above steps are repeated to obtain the sound velocity of shaft standard test block 6. Figure 2b As shown; finally, the bearing standard test block 5 and the shaft standard test block 6 were respectively installed on the coupling water tank 4 and the force sensor 7. Using a small syringe, water was dripped between the bearing standard test block 5 and the shaft standard test block 6, and the displacement platform 8 was moved down by 0.5 mm. The reflected echoes before and after the movement were collected (e.g., Figure 2c As shown in the figure, the speed of sound in water is calculated by determining the sound path difference caused by the movement.

[0037] 2. Remove the water between the bearing standard test block 5 and the shaft standard test block 6 to ensure the test block interface is dry. Set the pressure indicator 13 to zero and control the displacement platform 8 to move upwards until the force sensor 7 registers a reading, thus determining the initial contact state. Subsequently, adjust the first angular displacement platform 9 and the second angular displacement platform 10 sequentially until the force sensor 7 reading drops to 0N. Control the displacement platform 8 to move upwards again and repeat the above adjustment steps until it is observed that when the first angular displacement platform 9 and the second angular displacement platform 10 deflect slightly in any direction, the force sensor 7 reading shows a basically monotonically increasing trend. At this point, it can be determined that the friction pair interface has reached a parallel state.

[0038] 3. Control the displacement platform 8 to move down 1mm, and use the signal oscilloscope 16 and the host computer 17 to collect the signal of the bearing standard test block 5-air interface as a reference signal. Figure 3a As shown. Subsequently, a zero-padded Fourier transform is performed on the signal to obtain the amplitude of the reference signal ( ). Figure 3b ) and phase information ( Figure 3c ).

[0039] 4. Water is dropped onto the surface of the standard test block 6, and the initial film thickness is calculated using the ultrasonic resonance method. Subsequently, the displacement platform 8 is controlled to rise in steps of a specific size (e.g., 1 μm) to set water films of different thicknesses. After each film thickness adjustment, the corresponding reflected echo signal is collected.

[0040] 5. The collected water film reflection echo signal is subjected to zero-padded Fourier transform on the host computer 17 to obtain the corresponding amplitude and phase information. Then, the amplitude and phase are divided and subtracted from the reference signal, respectively, to calculate the reflection coefficient. The film thickness is then calculated using a film thickness algorithm. The calculated film thickness is compared with the theoretical film thickness obtained from the displacement platform 8 to evaluate the accuracy of the thickness measurement method. Figure 4a and Figure 4b As shown.

[0041] The liquid film thickness calibration device proposed in this embodiment has the following beneficial effects: 1. By integrating the first angular displacement platform 9 and the second angular displacement platform 10, and with the force sensor 7 placed between the shaft standard test block 6 and the displacement platform 8, the parallelism of the friction pair interface formed by the shaft standard test block 6 and the bearing standard test block 5 can be controlled. 2. This liquid film thickness calibration device has high flexibility and can adapt to the precise fit of the friction interface under different test block tilt angle adjustment requirements; 3. By adjusting the sensor installation position and the linear displacement stage, the installation angle of the ultrasonic sensor and its position in the straight line can be determined, thereby accurately locating the ultrasonic focal point and focal length parameters. 4. This liquid film thickness calibration device adopts a modular design concept, which supports the rapid replacement of key functional components, including friction pair test blocks, sensors, drive units, etc. It is convenient to flexibly configure experimental adjustments according to different bearing testing requirements (such as material type, friction conditions, environmental parameters, etc.), which improves the versatility and adaptability of the device, while significantly reducing maintenance costs and simplifying the functional upgrade process.

[0042] The present invention also proposes a thickness calibration method for a liquid film thickness calibration device.

[0043] In this preferred embodiment, a thickness calibration method based on the above-described liquid film thickness calibration device includes the following steps: Step S10: Install bearing standard test block 5 and shaft standard test block 6 below coupling water tank 4 respectively (the boss 51 of bearing standard test block 5 is inserted into the groove of coupling water tank 4 to seal the groove, and shaft standard test block 6 is placed below bearing standard test block 5, such as...). Figure 1As shown in the figure, with water filling the coupling tank 4, the sound velocity of the bearing standard test block 5 and the shaft standard test block 6 is obtained by collecting the reflected echoes from the upper and lower interfaces of the bearing standard test block 5 and the shaft standard test block 6 respectively. Step S20: Install bearing standard test block 5 and shaft standard test block 6 below the coupling water tank 4 (the boss 51 of bearing standard test block 5 is inserted into the groove of coupling water tank 4 to seal the groove, and shaft standard test block 6 is placed below bearing standard test block 5, such as...). Figure 1 As shown in the figure, water is dripped between bearing standard test block 5 and shaft standard test block 6, and displacement platform 8 is controlled to move down. The sound velocity of water is determined by collecting the reflected echoes of the test blocks before and after the displacement platform 8 moves. Step S30: Remove the water between the bearing standard test block 5 and the shaft standard test block 6, adjust the liquid film thickness calibration device to the initial state, and adjust the first angular displacement platform 9 and the second angular displacement platform 10 until the shaft standard test block 6 is parallel to the bearing standard test block 5. Then, control the displacement platform 8 to move down (it can move 1 mm), collect the signal of the bearing standard test block 5-air interface as a reference signal, and perform zero-padding Fourier transform on the reference signal to obtain the amplitude and phase information of the reference signal. Step S40: Water is dripped between bearing standard test block 5 and shaft standard test block 6. The initial film thickness is calculated using the ultrasonic resonance method. The displacement platform 8 is raised in a specific step size (e.g., 1 μm) to set water films of different thicknesses. After each film thickness adjustment, the corresponding water film reflection echo signal is collected. Step S50: Evaluate the accuracy of the thickness measurement method based on the amplitude and phase information of the water film reflected echo signal and the reference signal.

[0044] In step S30, the liquid film thickness calibration device is adjusted to its initial state. The specific process is as follows: The pressure indicator 13 is reset to zero, and the displacement platform 8 is moved upward until the force sensor 7 shows a reading, which is considered the initial state. The first angular displacement platform 9 and the second angular displacement platform 10 are adjusted until the shaft standard test block 6 is parallel to the bearing standard test block 5. The principle is as follows: When the first angular displacement platform 9 and the second angular displacement platform 10 are adjusted sequentially until the force sensor reading drops to 0N; the displacement platform 8 is moved upward again, and the above adjustment steps are repeated until it is observed that when the first angular displacement platform 8 and the second angular displacement platform 10 deflect slightly in any direction, the force sensor 7 reading shows a basically monotonically increasing trend. At this time, it can be determined that the friction pair interface has reached a parallel state.

[0045] Specifically, in step S50, evaluating the accuracy of the thickness measurement method based on the amplitude and phase information of the water film reflection echo signal and the reference signal includes: performing zero-padding Fourier transform on the acquired water film reflection echo signal in the host computer 17 to obtain the corresponding amplitude and phase information; dividing and subtracting the amplitude and phase of the reference signal respectively to calculate the reflection coefficient; using the reflection coefficient and film thickness algorithm to obtain the calculated film thickness; comparing the calculated film thickness with the theoretical film thickness obtained based on the displacement platform 8 (the theoretical film thickness is calculated based on the difference between the initial film thickness calculated in step S40 and the displacement of the displacement platform; for example, if the initial film thickness is 500 μm and the displacement platform moves up 10 μm, the theoretical film thickness is 490 μm) to evaluate the accuracy of the thickness measurement method.

[0046] The thickness calibration method proposed in this invention has the following beneficial effects: 1) Achieve dynamic adjustment of micron-level liquid film thickness. By applying a high-precision piezoelectric displacement platform, the challenge of dynamic adjustment of micron-level film thickness was solved; 2) Bearing friction pair interface parallelism adjustment device. By real-time monitoring of the contact force reading and adjustment of the angular displacement stage, the problem of high-precision parallelism adjustment of the friction pair contact interface can be solved; 3) Achieve precise positioning of the ultrasonic sensor. By cooperating with the sensor holding device and the linear displacement stage, the installation angle and linear position of the ultrasonic sensor can be precisely adjusted, the ultrasonic focal point can be accurately located, and the focal length parameter can be determined, thereby improving the accuracy and reliability of ultrasonic measurement; 4) Integration and ease of operation: The various modules of the device work in coordination to achieve parallelism adjustment, film thickness control and ultrasonic measurement, which improves the efficiency and repeatability of the lubricating film thickness calibration process.

[0047] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A liquid film thickness calibration device, characterized by, It includes a linear displacement stage, a sensor holding device, a water-immersion ultrasonic sensor, a coupling water tank, a force sensor, a displacement platform, a first angular displacement platform, and a second angular displacement platform, wherein... The sensor holding device and the coupling water tank frame are both located on one side of the linear displacement stage. The sensor holding device is located above the coupling water tank and is used to support the water immersion ultrasonic sensor. The bottom of the coupling water tank has an opening to seal and connect with the boss of the bearing standard test block. The displacement platform is located below the coupling water tank. The top surface of the upper moving plate of the displacement platform is used to place the force sensor to abut against the groove of the shaft standard test block. Below the displacement platform, a first angular displacement platform and a second angular displacement platform are arranged in sequence to drive the overall movement of the displacement platform to adjust the inclination angle of the upper moving plate and thus adjust the parallelism of the shaft standard test block relative to the bearing standard test block.

2. The liquid film thickness calibration device as described in claim 1, characterized in that, The water immersion ultrasonic sensor is electrically connected in sequence to an ultrasonic pulse transceiver, a signal oscilloscope, and a host computer.

3. The liquid film thickness calibration device as described in claim 1, characterized in that, The force sensor is electrically connected to a pressure indicator and a power module in sequence, and the displacement platform is electrically connected to a piezoelectric cascade controller to control the displacement distance and direction of the upper moving plate.

4. The liquid film thickness calibration device as described in claim 1, characterized in that, The rotation axes of the first angular displacement platform and the second angular displacement platform are set perpendicularly.

5. The liquid film thickness calibration device as described in claim 1, characterized in that, The sensor holding device is adjustable in height relative to the coupling water tank.

6. The liquid film thickness calibration device as described in claim 1, characterized in that, The sensor holding device has a through hole, and a washer is embedded in the through hole. The water-immersed ultrasonic sensor is inserted into the washer in the through hole to be supported on the sensor holding device.

7. The liquid film thickness calibration device as described in claim 1, characterized in that, The bottom surface of the outer wall of the coupling water tank is provided with a threaded hole for fasteners to pass through. The fasteners pass through the through hole of the shaft standard test block or bearing standard test block and the threaded hole of the coupling water tank, thereby fixing the shaft standard test block or bearing standard test block to the coupling water tank.

8. The liquid film thickness calibration device according to any one of claims 1 to 7, characterized in that, The displacement platform is a piezoelectric displacement platform with a stepping accuracy at the nm level and a displacement stroke at the output end at the mm level.

9. A thickness calibration method based on the liquid film thickness calibration device according to any one of claims 1 to 8, characterized in that, Includes the following steps: Bearing standard test blocks and shaft standard test blocks are installed below the coupling water tank. With the coupling water tank filled with water, the sound velocity of the bearing standard test blocks and shaft standard test blocks is obtained by collecting the reflected echoes from the upper and lower interfaces of the bearing standard test blocks and shaft standard test blocks respectively. Standard bearing test blocks and standard shaft test blocks are installed below the coupling water tank, and water is dripped between the standard bearing test blocks and the standard shaft test blocks. The displacement platform is controlled to move downward, and the sound velocity of the water is determined by collecting the reflected echoes of the test blocks before and after the displacement platform moves. Remove the water between the bearing standard test block and the shaft standard test block, adjust the liquid film thickness calibration device to the initial state, and adjust the first angular displacement platform and the second angular displacement platform until the shaft standard test block is parallel to the bearing standard test block. Then, control the displacement platform to move down, collect the signal of the bearing standard test block-air interface as a reference signal, and perform zero-padding Fourier transform on the reference signal to obtain the amplitude and phase information of the reference signal. Water was dripped between the bearing standard test block and the shaft standard test block. The initial film thickness was calculated using the ultrasonic resonance method. The displacement platform was raised in a specific step size to set water films of different thicknesses. After each film thickness adjustment, the corresponding water film reflection echo signal was collected. The accuracy of the thickness measurement method is evaluated based on the amplitude and phase information of the water film reflected echo signal and the reference signal.

10. The thickness calibration method of the liquid film thickness calibration device as described in claim 9, characterized in that, The method of evaluating the accuracy of the thickness measurement method based on the amplitude and phase information of the water film reflection echo signal and the reference signal specifically includes: performing zero-padding Fourier transform on the acquired water film reflection echo signal in the host computer to obtain the corresponding amplitude and phase information; dividing and subtracting the amplitude and phase of the reference signal respectively to calculate the reflection coefficient; using the reflection coefficient and film thickness algorithm to obtain the calculated film thickness; comparing the calculated film thickness with the theoretical film thickness obtained based on the displacement platform to evaluate the accuracy of the thickness measurement method.

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