Ultrasonic oil film thickness calibration platform suitable for friction pairs with different structural shapes

Abstract

The invention belongs to the field of ultrasonic oil film thickness measurement, discloses an ultrasonic oil film thickness calibration platform suitable for friction pairs with different structural shapes, and can finish true ultrasonic oil film thickness calibration of different friction pairs according to different design of a corresponding calibration test piece of the structural shapes of the measured friction pairs. The ultrasonic oil film thickness calibration platform comprises an upper beam, a side plate, a base, a structure-adjustable upper test plate, an oil groove, a structure-adjustable lower test plate, an ultrasonic probe tool, a nanometer displacement platform, a manual displacement platform, a pressure sensor, a manual platform adapter plate, a pressure sensor adapter plate and a probe tool gland. According to the ultrasonic oil film thickness calibration platform, the replaceable structure-adjustable upper test plate and the structure-adjustable lower test plate are designed and used for simulating the lubricating contact state of different bearing rollers and outer rings or other friction pairs with special shapes, and therefore ultrasonic oil film thickness calibration under a special structure is achieved.

Description

Technical Field

[0001] The invention belongs to the field of ultrasonic oil film thickness measurement and relates to an ultrasonic oil film thickness calibration platform suitable for friction pairs with different structural shapes. Background Art

[0002] Lubrication is a key guarantee for the reliability of mechanical equipment and is also a typical weak link. The oil film thickness is the most intuitive representation of the lubrication status. Traditional oil film thickness testing methods are mainly divided into electrical testing methods, optical testing methods, and ultrasonic testing methods. Among them, the resistance method is one of the earliest methods used for lubricant film thickness measurement. Brix in the UK first used the resistance method to measure oil film thickness and fitted a curve showing the relationship between oil film thickness and resistance. This method is simple in principle, but the difference in resistance change for different film thicknesses is very small, and it is easily affected by changes in the external environment. Later, to compensate for the shortcomings of the resistance method, researchers developed the capacitance method to measure oil film thickness. Dyson et al. used a double-disk capacitance measurement device to test oil film thickness and proved the consistency between theoretical and measured values. This method has higher accuracy than the resistance method, but parasitic capacitance and fluctuations in the dielectric constant of the lubricant film during measurement can lead to reduced test accuracy. When the oil film is too thin, electrical breakdown will occur, making film thickness measurement impossible. Subsequently, researchers proposed the eddy current method. Gu Yongquan et al. used this method to test the oil film thickness of the mechanical seal end face and analyzed the influence of factors such as temperature and end face waviness on the test results. This method has higher test accuracy but requires structural modification on the surface of the measured object, which affects the structural strength of the measured object. Optical interferometry is the most commonly used optical test method for lubricating film thickness. Wen Shizhu and others used the optical interferometry method to test the oil film thickness and shape of point contact elastohydrodynamic lubrication. This method has very high accuracy but is limited by the light transmittance characteristics of the object being tested and cannot be applied in actual engineering. Existing ultrasonic testing research mainly focuses on water immersion ultrasound. Wang Jianyun and others used the water immersion ultrasound method to test the minimum oil film thickness. The advantage of this method is that the signal intensity is high and the test position is more focused, which can measure thinner oil films. However, since this method requires the probe to be immersed in a water tank during the test, it has high requirements on the test position and the test environment, and is extremely difficult to apply in actual engineering.

[0003] To address these issues, this paper proposes an ultrasonic oil film thickness calibration platform suitable for friction pairs with varying structural shapes. This calibration platform is compatible with standard bulk wave straight probes, which are unaffected by the test location and environment, are easy to assemble and disassemble, and have excellent prospects for engineering application. Compared to immersion ultrasonic probes, bulk wave straight probes are affected by the diameter of the wafer, and the echo received during the test is significantly affected by the structure of the object being tested. To determine the relationship between oil film thickness and ultrasonic reflection signals for a specific friction pair structure, an ultrasonic oil film thickness calibration platform suitable for friction pairs with varying structural shapes is urgently needed. Summary of the Invention

[0004] This invention is an ultrasonic oil film thickness calibration platform suitable for friction pairs with varying structural shapes. It aims to address the problem of bulk wave direct probes being affected by the diameter of the wafer, resulting in the echo received during testing being significantly influenced by the structure of the object being measured. This platform accurately measures the relationship between oil film thickness and ultrasonic signals for various friction pair configurations. By designing interchangeable upper and lower test plates, controlled jointly by a nano-displacement platform and a manual displacement platform, precise submicron control of oil film thickness for various friction pair configurations is achieved, thus enabling calibration of ultrasonic oil film testing methods.

[0005] The technical solution of the present invention:

[0006] An ultrasonic oil film thickness calibration platform suitable for friction pairs with different structural shapes includes an upper beam, side plates, a base, a structurally adjustable upper test plate, an oil tank, a structurally adjustable lower test plate, an ultrasonic probe tooling, a nano-displacement platform, a manual displacement platform, a pressure sensor, a manual platform adapter plate, a pressure sensor adapter plate, a probe tooling cover, a sealing rubber ring and a spring. The manual displacement platform is installed on the base, the pressure sensor is connected to the manual displacement platform through the manual platform adapter plate, the nano displacement platform is connected to the pressure sensor through the pressure sensor adapter plate, the upper end of the nano displacement platform is connected to the probe tooling cover, the probe tooling cover is connected to the ultrasonic probe tooling, the ultrasonic probe tooling is connected to the structurally adjustable lower test plate, the oil tank is installed in the groove of the structurally adjustable lower test plate, and sealing is achieved by a sealing rubber ring. The ultrasonic probe is installed in the ultrasonic probe tooling so that the ultrasonic probe rests on the structurally adjustable test lower plate, and a pre-tightening force is provided by a spring and the probe tooling cover. The side plate is installed on the base, the upper beam is installed on the side plate, and the structurally adjustable upper test plate is installed on the upper beam, so that the boss structure of the structurally adjustable upper test plate is opposite to the boss structure of the structurally adjustable lower test plate and can be smoothly inserted into the oil tank.

[0007] The manual platform adapter plate, pressure sensor adapter plate, probe tooling gland, and probe tooling require precision machining.

[0008] The matching parts of the base and the side panels need to be provided with bosses for fine processing.

[0009] The matching part between the base and the manual displacement platform needs to be provided with a boss for fine processing.

[0010] The mating parts of the side panels and the upper beams need to be provided with bosses for fine processing.

[0011] The structurally adjustable upper test plate and the structurally adjustable lower test plate need to be structurally designed according to the friction pair object to be tested, and the tested surface and bottom surface both need to be finely machined.

[0012] Beneficial effects of the present invention:

[0013] The present invention designs a structurally adjustable upper test plate and a structurally adjustable lower test plate, which can be adjusted according to different friction pair structural shapes, thereby realizing the calibration of the relationship between the ultrasonic signal and the oil film thickness under different friction pair structural shapes.

[0014] The present invention has a simple structure, a small volume, and is easy to process through modular design, and is applicable to the calibration of side-lead straight probes of various sizes and frequencies.

[0015] The present invention determines the zero position by using a high-precision pressure sensor, and can control the zero position error within 0.05 μm.

[0016] The present invention can quantitatively explore the relationship between the ultrasonic reflection coefficient and the minimum oil film thickness when the ultrasonic probe is located at various positions of the friction pair by adjusting the manual displacement platform, providing data support for error compensation and fault diagnosis in actual engineering applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the overall structure of the calibration platform.

[0018] Figure 2 This is a partial schematic diagram of the probe installation method.

[0019] Figure 3 Schematic diagram of the structurally adjustable test plate; (a) is the test plate on the spherical surface, and (b) is the test plate on the curved surface.

[0020] Figure 4 Schematic diagram of the structurally adjustable test plate; (a) is the test plate under the rolling track, and (b) is the test plate under the curved surface.

[0021] Figure 5 Schematic diagram of the bearing to be tested; (a) is a deep groove ball bearing and (b) is a cylindrical roller bearing.

[0022] In the figure: 1 side panel; 2 upper beam; 3 structurally adjustable upper test plate; 3a test plate on spherical surface; 3b test plate on arc surface; 4 oil tank; 5 structurally adjustable lower test plate; 5a test plate under rolling path; 5b test plate under curved surface; 6 ultrasonic probe fixture; 7 probe fixture pressure cover; 8 nanometer displacement platform; 9 pressure sensor adapter plate; 10 pressure sensor; 11 manual platform adapter plate; 12 manual displacement platform; 13 base; 14 sealing rubber ring; 15 ultrasonic probe; 16 spring; 17 deep groove ball bearing; 18 cylindrical roller bearing. DETAILED DESCRIPTION

[0023] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0024] An ultrasonic oil film thickness calibration platform suitable for friction pairs of different structural shapes, comprising a side plate 1, an upper beam 2, a structurally adjustable upper test plate 3, an oil tank 4, a structurally adjustable lower test plate 5, an ultrasonic probe tooling 6, a probe tooling gland 7, a nano-displacement platform 8, a pressure sensor adapter plate 9, a pressure sensor 10, a manual platform adapter plate 11, a manual displacement platform 12, a base 13, a sealing rubber ring 14, an ultrasonic probe 15, and a spring 16;

[0025] The manual displacement platform 12 is mounted on the base 13, and the control knob on the manual displacement platform 12 is controlled to enable the platform to move in three directions: front, back, left, right, and up and down. The pressure sensor 10 is connected to the manual displacement platform 12 through the manual platform adapter plate 11. The nano displacement platform 8 is connected to the pressure sensor 10 through the pressure sensor adapter plate 9. The upper end of the nano displacement platform 8 is connected to the probe tooling gland 7, the probe tooling gland 7 is connected to the ultrasonic probe tooling 6, and the ultrasonic probe tooling 6 is connected to the structurally adjustable lower test plate 5. The oil tank 4 is installed in the groove of the structurally adjustable lower test plate 5, and the sealing is achieved by the sealing rubber ring 14. The ultrasonic probe 15 is installed in the ultrasonic probe tooling 6 so that the ultrasonic probe 15 is against the structurally adjustable lower test plate 5. The ultrasonic probe 15 provides pre-tightening force through the spring 16 and the probe tooling pressure cover 7. The side plate 1 is installed on the base 13, the upper beam 2 is installed on the side plate 1, and the structurally adjustable upper test plate 3 is installed on the upper beam 2, so that the boss structure of the structurally adjustable upper test plate 3 can face the boss structure of the structurally adjustable lower test plate 5, and can be smoothly inserted into the oil tank 4.

[0026] In this embodiment, two sets of structurally adjustable upper test plates 3 and structurally adjustable lower test plates 5 are designed to address the friction pair characteristics of deep groove ball bearings 17 and cylindrical roller bearings 18. These plates are respectively: a spherical test plate 3a and a lower raceway test plate 5a, and an arcuate test plate 3b and a lower curved test plate 5b. The spherical test plate 3a and the lower raceway test plate 5a correspond to the friction pair structural characteristics of deep groove ball bearings 17, while the arcuate test plate 3b and the lower curved test plate 5b correspond to the friction pair structural characteristics of cylindrical roller bearings 18. The spherical curvature radius of the spherical test plate 3a is consistent with the roller radius of the deep groove ball bearing 17 to be tested, while the arcuate test plate 3b is consistent with the cylindrical roller radius of the cylindrical roller bearing 18 to be tested. The raceway curvature radius of the lower raceway test plate 5a is consistent with the raceway curvature radius of the deep groove ball bearing 17 to be tested, while the raceway curvature radius of the lower curved test plate 5b is consistent with the raceway curvature radius of the cylindrical roller bearing 18 to be tested.

[0027] The manual platform adapter plate 11, pressure sensor adapter plate 9, probe tooling cover 7, and probe tooling 6 described in this embodiment need to be finely processed to ensure that the surface roughness is Ra1.6, the parallelism error of the upper and lower surfaces is less than 0.02, and the flatness error of the upper and lower surfaces is less than 0.02.

[0028] In this embodiment, the mating portion of the base 13 and the side panel 1 needs to be provided with a boss for fine processing, the boss surface flatness error is less than 0.02, and the boss surface and the bottom surface of the base 13 parallelism error is less than 0.02, ensuring that the boss surface roughness Ra1.6.

[0029] In this embodiment, the mating part of the base 13 and the manual displacement platform 12 needs to be provided with a boss for fine processing. The flatness error of the boss surface is less than 0.02, and the parallelism error between the boss surface and the bottom surface of the base 13 is less than 0.02, ensuring that the boss surface roughness is Ra1.6.

[0030] In this embodiment, the mating part of the side panel 1 and the upper beam 2 needs to be provided with a boss for fine processing. The flatness error of the boss surface is less than 0.02, and the verticality error between the boss surface and the bottom surface of the side panel 1 is less than 0.02. The surface roughness of the boss is guaranteed to be Ra1.6. The mating position of the side panel 1 and the upper beam 2 needs to be provided with a positioning pin to ensure the positioning accuracy.

[0031] In this embodiment, the surface of the adjustable upper test plate 3 involved in the test needs to be provided with a boss with a length of 6 mm. The surface of the boss is the tested surface, the boss diameter is 8 mm, and the cross-sectional shape of the boss is determined by the friction shape of the calibration object.

[0032] In this embodiment, a boss with a length of 3 mm is set on the surface of the adjustable lower test plate 5. The surface of the boss is the measured surface, the diameter of the boss is 8 mm, and the cross-sectional shape of the boss is determined by the friction shape of the calibration object.

[0033] In the oil film calibration process of this embodiment, the manual displacement platform 12 is first controlled to gradually bring the adjustable lower test plate 5 close to the adjustable upper test plate 3 so that the pressure sensor 10 reads 2N. At this time, the adjustable lower test plate 5 is already in close contact with the adjustable upper test plate 3, the minimum oil film thickness of the friction pair is zero, but the load is 2N. Then, the nano-displacement platform 8 is fine-tuned in units of 0.01 μm to gradually reduce the reading of the pressure sensor 10 until it is just zero. At this time, the adjustable lower test plate 5 and the adjustable upper test plate 3 are about to separate, the minimum oil film thickness of the friction pair is still zero, but the load is zero, and this is the zero position of the minimum oil film thickness of the friction pair. On this basis, the nano-displacement platform 8 is controlled to increase the distance between the adjustable lower test plate 5 and the adjustable upper test plate 3 from 0 μm to 100 μm. By collecting the echo signal of the ultrasonic probe 15 and recording the current distance between the adjustable lower test plate 5 and the adjustable upper test plate 3, the ultrasonic signal calibration suitable for the current friction pair structure can be completed.

Claims

1. An ultrasonic oil film thickness calibration platform suitable for friction pairs of different structures and shapes, characterized by: The ultrasonic oil film thickness calibration platform comprises a side plate (1), an upper beam (2), a structurally adjustable upper test plate (3), an oil tank (4), a structurally adjustable lower test plate (5), an ultrasonic probe tool (6), a probe tool pressure cover (7), a nano-displacement platform (8), a pressure sensor adapter plate (9), a pressure sensor (10), a manual platform adapter plate (11), a manual displacement platform (12), a base (13), a sealing rubber ring (14), an ultrasonic probe (15) and a spring (16); The manual displacement platform (12) is mounted on a base (13), and the ultrasonic oil film thickness calibration platform is controlled to move in three directions, front-back, left-right, and up-down, by controlling the manual displacement platform (12); the pressure sensor (10) is connected to the manual displacement platform (12) via a manual platform adapter plate (11); the nano displacement platform (8) is connected to the pressure sensor (10) via a pressure sensor adapter plate (9); the upper end of the nano displacement platform (8) is connected to a probe tooling gland (7); the probe tooling gland (7) is connected to an ultrasonic probe tooling (6); the ultrasonic probe tooling (6) is connected to a structurally adjustable lower test plate (5); and the oil tank (4) is mounted on the structurally adjustable lower test plate (5). The groove of the test plate (5) is sealed by a sealing rubber ring (14); the ultrasonic probe (15) is installed in the ultrasonic probe fixture (6), so that the ultrasonic probe (15) extends from the slide groove on the ultrasonic probe fixture (6) and rests on the structurally adjustable lower test plate (5), and the ultrasonic probe (15) provides a pre-tightening force through the spring (16) and the probe fixture pressure cover (7); the side plate (1) is installed on the base (13), the upper beam (2) is installed on the side plate (1), and the structurally adjustable upper test plate (3) is installed on the upper beam (2), so that the boss structure of the structurally adjustable upper test plate (3) is opposite to the boss structure of the structurally adjustable lower test plate (5), and can be smoothly inserted into the oil tank (4).

2. The ultrasonic oil film thickness calibration platform according to claim 1, characterized in that: Two sets of structurally adjustable upper test plates (3) and structurally adjustable lower test plates (5) are designed for the friction pairs of deep groove ball bearings (17) and cylindrical roller bearings (18), which are respectively the upper test plate (3a) on the spherical surface and the lower test plate (5a) on the rolling track, and the upper test plate (3b) on the arc surface and the lower test plate (5b) on the curved surface; wherein the upper test plate (3a) on the spherical surface and the lower test plate (5a) on the rolling track correspond to the friction pair structure of the deep groove ball bearing (17), and the upper test plate (3b) on the arc surface and the lower test plate (5b) on the curved surface correspond to the friction pair structure of the cylindrical roller bearing (18). ) friction pair structure; wherein the spherical curvature radius of the test plate (3a) on the spherical surface is consistent with the roller radius of the deep groove ball bearing (17) to be tested, and the arc curvature radius of the test plate (3b) on the arc surface is consistent with the cylindrical roller radius of the cylindrical roller bearing (18) to be tested; the raceway curvature radius in the test plate (5a) under the raceway is consistent with the raceway curvature radius of the deep groove ball bearing (17) to be tested, and the raceway curvature radius in the test plate (5b) under the curved surface is consistent with the raceway curvature radius of the cylindrical roller bearing (18) to be tested.

3. The ultrasonic oil film thickness calibration platform according to claim 1, characterized in that: The surface of the structurally adjustable upper test plate (3) involved in the test is a boss with a length of 6 mm, the surface of the boss is the surface to be tested, the diameter of the boss is 8 mm, and the cross-sectional shape of the boss is determined by the friction shape of the calibration object.

4. The ultrasonic oil film thickness calibration platform according to claim 1, characterized in that: The surface of the structurally adjustable lower test plate (5) is provided with a boss with a length of 3 mm, the surface of the boss is the surface to be tested, the diameter of the boss is 8 mm, and the cross-sectional shape of the boss is determined by the friction shape of the calibration object.

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