Minimum oil film thickness calibration method considering different friction pair shape structures

Abstract

The invention belongs to the field of ultrasonic oil film thickness measurement, and discloses a minimum oil film thickness calibration method considering different friction pair shape structures, which utilizes an ultrasonic oil film thickness calibration platform capable of designing a corresponding calibration test piece according to different structure shapes of a measured friction pair, and aims at the shape structure characteristics of different friction pairs. The minimum oil film thicknesses of friction pairs with different shapes and structures are accurately controlled, ultrasonic reflection signals under the different minimum oil film thicknesses are collected and subjected to frequency domain analysis processing, and on the basis, polynomial fitting is conducted on the minimum oil film thicknesses and reflection coefficients in combination with a film thickness calculation model; and the ultrasonic minimum oil film thickness calibration under a special friction pair structure is realized.

Description

Technical Field

[0001] The invention belongs to the field of ultrasonic oil film thickness measurement and relates to a minimum oil film thickness calibration method considering different friction pair shape structures. Background Art

[0002] Lubrication is the lifeline of mechanical parts and a key link in the reliable operation of equipment. The most intuitive representation of lubrication status is the thickness of the lubricating film. The existing in-situ measurement method of lubricating film thickness is mainly based on ultrasonic testing method. The existing ultrasonic testing methods are mainly divided into water immersion ultrasonic testing method, patch testing method and straight probe testing method. The advantage of the water immersion ultrasonic testing method is that it is highly sensitive to oil film thickness below 1μm. Harbin Institute of Technology used the water immersion ultrasonic method to measure the minimum oil film thickness of rolling bearings. Although this method has high signal intensity at the focal spot position and can measure thinner oil films, the probe needs to be immersed in a water tank during the test. This has high requirements for the test position and the test environment, and is extremely difficult to apply in actual engineering. Compared with the water immersion ultrasonic method, the patch testing method does not require an additional water tank. Xi'an Jiaotong University used the patch method to attach a piezoelectric piece with a width of 0.6mm to the outer ring of the bearing to complete the oil film thickness measurement of the cylindrical roller bearing. Although this method avoids the need to set up an additional water tank, the method of patching the outer ring of the bearing puts higher requirements on the bearing disassembly and assembly process, and is limited by the shape of the piezoelectric patch. At present, this method can only be applied to cylindrical roller bearings and cannot be applied to ball bearings; the straight probe test method does not require changes to the process for bearing disassembly and assembly compared to the patch method. The University of Sheffield used a straight probe to test the oil film thickness using the acoustic reflection method. This method only requires a hole in the bearing seat to accommodate the straight probe to complete the test, but is limited by the diameter size of the straight probe chip. This method can only be used for oil film thickness testing between parallel structures.

[0003] Based on the above problems, the body wave probe test method has good engineering prospects but is greatly affected by the shape and structure of the friction pair. The existing methods and theories assume that the objects to be measured are the oil film thickness between parallel plates. In order to solve this problem and make the straight probe test method adapt to the minimum oil film thickness test requirements between different types of friction pairs, a minimum oil film thickness calibration method that takes into account the different shapes and structures of friction pairs is urgently needed. Summary of the Invention

[0004] This invention provides a minimum oil film thickness calibration method that considers different friction pair shapes and structures. Its purpose is to address the problem that the echo received during the test of a bulk wave direct probe is significantly affected by the structure of the object being measured due to the influence of the wafer diameter, resulting in a non-linear relationship between oil film thickness and ultrasonic reflection coefficient. By utilizing an ultrasonic oil film thickness calibration platform suitable for friction pairs with different structural shapes, a minimum oil film thickness calibration method that considers different friction pair shapes and structures is provided. The calibration platform precisely controls the minimum oil film thickness between friction pairs at the submicron level, collects ultrasonic reflection signals at different oil film thicknesses, and finally performs nonlinear fitting to determine the relationship between minimum oil film thickness and ultrasonic reflection coefficient.

[0005] The technical solution of the present invention:

[0006] A method for calibrating the minimum oil film thickness considering different friction pair shapes and structures, the steps are as follows:

[0007] S1. Constructing an ultrasonic oil film thickness calibration platform used in a small oil film thickness calibration method;

[0008] The ultrasonic oil film thickness calibration platform includes a test bench 1, a test upper plate 2, an oil tank 3, a test lower plate 4, an ultrasonic probe tooling 5, a nano-displacement platform 6, a pressure sensor 7, a manual displacement platform 8, an ultrasonic probe 9, a spring 10, a probe tooling cover 14, an oscilloscope, a platform controller and a host computer; wherein, the manual displacement platform 8 is installed on the base of the test bench 1, with the direction facing the test bench 1 as the reference, the front and back direction is the x-axis, the left and right direction is the y-axis, and the up and down direction is the z-axis. By controlling the knob of the manual displacement platform 8, the platform can be moved along the x-axis, y-axis and z-axis. The pressure sensor 7 is installed on the manual displacement platform 8, and the nano-displacement platform 6 is installed on the pressure sensor 7. The nano-displacement platform 6 is controlled by the operating platform controller to achieve sub-micron high repeatability and precise positioning, ultra-high precision positioning. The acoustic probe tooling 5 is installed on the nano-displacement platform 6 through the probe pressure cover tooling 14, the test lower plate 4 is installed on the ultrasonic probe tooling 5, the oil tank 3 is installed on the test lower plate 4, and the test upper plate 2 is installed on the upper beam of the test bench 1, and it is ensured that the boss structure of the test upper plate 2 is facing the boss structure of the test lower plate 4 and can smoothly enter the oil tank 3; the ultrasonic probe 9 is installed in the ultrasonic probe tooling 5, so that the ultrasonic probe 9 extends from the slide groove on the ultrasonic probe tooling 5 and rests on the test lower plate 4 so that the center of the ultrasonic probe 9 can face the boss structure of the test lower plate 4, and the ultrasonic probe 9 is provided with a pre-tightening force through the spring 10 and the probe tooling pressure cover 14; the ultrasonic probe 9 is connected to the oscilloscope, and the host computer is connected to the oscilloscope and the platform controller respectively. The reading of the oscilloscope data and the operation of the platform controller are realized by operating the host computer;

[0009] S2. Leave the oil tank 3 empty, ensuring that the test lower plate 4 is in direct contact with air. Record the echo signal P0 of the ultrasonic probe 9 at this time, perform Fourier transform on the echo signal P0, extract the Fourier transform result corresponding to the center frequency, calculate its absolute value, record it as I0, and save it to the host computer. Record the peak value vpp0 of the ultrasonic echo displayed on the oscilloscope at this time;

[0010] S3. Initially ensure that the upper test plate 2 and the lower test plate 4 are aligned by controlling the manual displacement platform 8 so that the center eccentricity of the bosses of the upper test plate 2 and the lower test plate 4 does not exceed -2 mm to +2 mm. Then, control the manual displacement platform 8 to gradually raise the lower test plate 4 closer to the upper test plate 2 until the peak value vpp1 of the ultrasonic probe 9 echo displayed on the oscilloscope decreases by 15% to 25% compared to the peak value vpp0 of the ultrasonic echo.

[0011] S4. Control the manual displacement platform 8 to make the test lower plate 4 reciprocate relative to the test upper plate 2 along the x-axis and y-axis in units of the minimum scale value of the manual displacement platform 8. The movement range of the x-axis and y-axis is -3 mm to +3 mm. Record the x-axis and y-axis coordinates of the manual displacement platform 8 and the echo signal of the ultrasonic probe 9 after each movement. Find the x-axis and y-axis coordinates at which the peak-to-peak value of the echo signal of the ultrasonic probe 9 is minimized. Adjust the manual displacement platform 8 to be at the above coordinates and lock the x-axis and y-axis of the manual displacement platform 8 to prevent subsequent operations from changing the relative position of the test upper plate 2 and the test lower plate 4 so that the ultrasonic probe 9 cannot face the minimum oil film thickness of the friction pair.

[0012] S5. Control the manual displacement platform 8 to move the lower test plate 4 closer to the upper test plate 2 until the pressure sensor 7 reads 2N. At this point, the lower test plate 4 is in close contact with the upper test plate 2, and the load is 2N.

[0013] S6. Control the nano-displacement platform 6 to gradually move the lower test plate 4 away from the upper test plate 2 in units of 1 μm until the pressure sensor 7 reads 0.2 N. Further control the nano-displacement platform 6 to gradually move the lower test plate 4 away from the upper test plate 2 in units of 0.05 μm until the pressure sensor 7 reads exactly 0 N. At this point, the position of the lower test plate 4 is considered to be the zero position of the oil film thickness.

[0014] S7, record the echo signal P1 of the ultrasonic probe 9 at zero position, then control the nano displacement platform 6 to gradually move the test lower plate 4 away from the test upper plate 2 in units of 0.5 μm, and record the echo signal P1 of the ultrasonic probe 9 after each test after the distance between the test lower plate 4 and the test upper plate 2 changes. n And the distance h between the test lower plate 4 and the test upper plate 2 n , for the echo signal P n Perform Fourier transform, extract the center frequency and calculate the absolute value of the result, which is recorded as I n , will be saved to the host computer;

[0015] S8, the result after Fourier transformation of each echo of the ultrasound probe 9 is converted into n Substitute into the reflection coefficient calculation formula R n =I n / I0, get the distance h between the upper test plate 2 and the lower test plate 4 n The corresponding ultrasonic reflection coefficient is substituted into the calibration formula as follows: Using nonlinear least squares method to estimate R'n and h n The nonlinear least squares calibration curve is recorded as Complete the calibration of oil film thickness.

[0016] Beneficial effects of the present invention:

[0017] The present invention takes into account the influence of the friction pair shape structure on the straight probe echo, abandons the traditional linear calibration method, and selects a nonlinear calibration method. It can adapt to the minimum oil film thickness calibration of different friction pair structures and significantly improves the test accuracy.

[0018] The calibration platform used in the present invention can not only calibrate the ultrasonic probe at the position of the minimum oil film thickness of the friction pair through the manual displacement platform, but also quantitatively explore the relationship between the ultrasonic reflection coefficient and the oil film thickness when the probe deviates from the position of the minimum oil film thickness of the friction pair by a specific distance, providing data support for error compensation and fault diagnosis in actual engineering applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the test system.

[0020] Figure 2 Schematic diagram of the probe installation method.

[0021] Figure 3 Schematic diagram of the bearing to be tested.

[0022] Figure 4 Schematic diagram of the test upper plate and the test lower plate, where (a) is the test upper plate and (b) is the test lower plate.

[0023] Figure 5 This is a schematic diagram of the measurement probe placement.

[0024] Figure 6 Schematic diagram of the nonlinear relationship between the calibration reflection coefficient and the minimum oil film thickness.

[0025] Figure 7 This is a comparison chart of the results of the nonlinear calibration method in this paper and the traditional spring model linear calibration method.

[0026] In the figure: 1 test bench; 2 test upper plate; 3 oil tank; 4 test lower plate; 5 ultrasonic probe fixture; 6 nanometer displacement platform; 7 pressure sensor; 8 manual displacement platform; 9 ultrasonic probe; 10 spring; 11 cylindrical roller bearing; 11a cylindrical roller; 11b cylindrical roller bearing outer ring; 12 probe hole; 13 bearing seat; 14 probe fixture cover. DETAILED DESCRIPTION

[0027] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0028] A method for calibrating the minimum oil film thickness considering different friction pair shapes and structures, the steps are as follows:

[0029] S1. Constructing an ultrasonic oil film thickness calibration platform used in a small oil film thickness calibration method;

[0030] The ultrasonic oil film thickness calibration platform includes a test bench 1, a test upper plate 2, an oil tank 3, a test lower plate 4, an ultrasonic probe tooling 5, a nano-displacement platform 6, a pressure sensor 7, a manual displacement platform 8, an ultrasonic probe 9, a spring 10, a probe tooling cover 14, an oscilloscope, a platform controller and a host computer; wherein, the manual displacement platform 8 is installed on the base of the test bench 1, with the direction facing the test bench 1 as the reference, the front and back direction is the x-axis, the left and right direction is the y-axis, and the up and down direction is the z-axis. By controlling the knob of the manual displacement platform 8, the platform can be moved along the x-axis, y-axis and z-axis. The pressure sensor 7 is installed on the manual displacement platform 8, and the nano-displacement platform 6 is installed on the pressure sensor 7. The nano-displacement platform 6 is controlled by the operating platform controller to achieve sub-micron high repeatability and precise positioning, ultra-high precision positioning. The acoustic probe tooling 5 is installed on the nano-displacement platform 6 through the probe pressure cover tooling 14, the test lower plate 4 is installed on the ultrasonic probe tooling 5, the oil tank 3 is installed on the test lower plate 4, and the test upper plate 2 is installed on the upper beam of the test bench 1, and it is ensured that the boss structure of the test upper plate 2 is facing the boss structure of the test lower plate 4 and can smoothly enter the oil tank 3; the ultrasonic probe 9 is installed in the ultrasonic probe tooling 5, so that the ultrasonic probe 9 extends from the slide groove on the ultrasonic probe tooling 5 and rests on the test lower plate 4 so that the center of the ultrasonic probe 9 can face the boss structure of the test lower plate 4, and the ultrasonic probe 9 is provided with a pre-tightening force through the spring 10 and the probe tooling pressure cover 14; the ultrasonic probe 9 is connected to the oscilloscope, and the host computer is connected to the oscilloscope and the platform controller respectively. The reading of the oscilloscope data and the operation of the platform controller are realized by operating the host computer;

[0031] S2. Leave the oil tank 3 empty, ensuring that the test lower plate 4 is in direct contact with air. Record the echo signal P0 of the ultrasonic probe 9 at this time, perform Fourier transform on the echo signal P0, extract the Fourier transform result corresponding to the center frequency, calculate its absolute value, record it as I0, and save it to the host computer. Record the peak value vpp0 of the ultrasonic echo displayed on the oscilloscope at this time;

[0032] S3. Initially ensure that the upper test plate 2 and the lower test plate 4 are aligned by controlling the manual displacement platform 8 so that the center eccentricity of the bosses of the upper test plate 2 and the lower test plate 4 does not exceed -2 mm to +2 mm. Then, control the manual displacement platform 8 to gradually raise the lower test plate 4 closer to the upper test plate 2 until the peak value vpp1 of the ultrasonic probe 9 echo displayed on the oscilloscope decreases by 15% to 25% compared to the peak value vpp0 of the ultrasonic echo.

[0033] S4. Control the manual displacement platform 8 to make the test lower plate 4 reciprocate relative to the test upper plate 2 along the x-axis and y-axis in units of the minimum scale value of the manual displacement platform 8. The movement range of the x-axis and y-axis is -3 mm to +3 mm. Record the x-axis and y-axis coordinates of the manual displacement platform 8 and the echo signal of the ultrasonic probe 9 after each movement. Find the x-axis and y-axis coordinates at which the peak-to-peak value of the echo signal of the ultrasonic probe 9 is minimized. Adjust the manual displacement platform 8 to be at the above coordinates and lock the x-axis and y-axis of the manual displacement platform 8 to prevent subsequent operations from changing the relative position of the test upper plate 2 and the test lower plate 4 so that the ultrasonic probe 9 cannot face the minimum oil film thickness of the friction pair.

[0034] S5. Control the manual displacement platform 8 to move the lower test plate 4 closer to the upper test plate 2 until the pressure sensor 7 reads 2N. At this point, the lower test plate 4 is in close contact with the upper test plate 2, and the load is 2N.

[0035] S6. Control the nano-displacement platform 6 to gradually move the lower test plate 4 away from the upper test plate 2 in units of 1 μm until the pressure sensor 7 reads 0.2 N. Further control the nano-displacement platform 6 to gradually move the lower test plate 4 away from the upper test plate 2 in units of 0.05 μm until the pressure sensor 7 reads exactly 0 N. At this point, the position of the lower test plate 4 is considered to be the zero position of the oil film thickness.

[0036] S7, record the echo signal P1 of the ultrasonic probe 9 at zero position, then control the nano displacement platform 6 to gradually move the test lower plate 4 away from the test upper plate 2 in units of 0.5 μm, and record the echo signal P1 of the ultrasonic probe 9 after each test after the distance between the test lower plate 4 and the test upper plate 2 changes. n And the distance h between the test lower plate 4 and the test upper plate 2 n , for the echo signal P n Perform Fourier transform, extract the center frequency and calculate the absolute value of the result, which is recorded as I n , will be saved to the host computer;

[0037] S8, the result after Fourier transformation of each echo of the ultrasound probe 9 is converted into n Substitute into the reflection coefficient calculation formula R n =I n / I0, get the distance h between the upper test plate 2 and the lower test plate 4n The corresponding ultrasonic reflection coefficient is substituted into the calibration formula as follows: Using nonlinear least squares method to estimate R'n and h n The nonlinear least squares calibration curve is recorded as Complete the calibration of oil film thickness.

[0038] During the actual test after calibration, a probe hole 12 is first set on the bearing seat 13. Then, the ultrasonic probe 9 is installed above the cylindrical roller bearing 11 to be tested in a non-lubricated state, and the echo of the ultrasonic probe 9 is recorded as A0.

[0039] Then, the test is carried out under the lubrication condition to be tested, and the echo of the ultrasonic probe 9 is recorded as A n ;

[0040] A0 and A n Substitute the reflection coefficient calculation formula to obtain the reflection coefficient R An =A n / A0, the reflection coefficient R An Substitute the calibration formula to obtain the ultrasonic calibration reflection coefficient under the lubrication state to be measured: Then the ultrasonic calibration reflection coefficient R′ An Substitute it into the nonlinear least squares calibration curve to obtain the minimum oil film thickness under the current lubrication state to be measured

[0041] The bearing is a cylindrical roller bearing 11. The test upper plate 2 and the test lower plate 4 are structurally designed according to the friction pair structure of the cylindrical roller bearing 11. The test upper plate 2 is simplified by the cylindrical roller 11a structure, and its boss width is 8mm. The test lower plate 4 is simplified by the cylindrical roller bearing outer ring 11b structure, and its boss diameter is 8mm.

[0042] The beneficial effects of the present invention are as follows: the present invention takes into account the influence of the friction pair shape structure on the straight probe echo, abandons the traditional linear calibration method, selects the nonlinear calibration method, can adapt to the minimum oil film thickness calibration of different friction pair structures, and significantly improves the test accuracy.

Claims

1. A method for calibrating the minimum oil film thickness considering different friction pair shapes and structures, characterized in that: Here are the steps: S1. Constructing an ultrasonic oil film thickness calibration platform used in a small oil film thickness calibration method; The ultrasonic oil film thickness calibration platform comprises a test bench (1), a test upper plate (2), an oil tank (3), a test lower plate (4), an ultrasonic probe tooling (5), a nano-displacement platform (6), a pressure sensor (7), a manual displacement platform (8), an ultrasonic probe (9), a spring (10), a probe tooling pressure cover (14), an oscilloscope, a platform controller and a host computer; wherein, the manual displacement platform (8) is installed on the base of the test bench (1), with the direction facing the test bench (1) as a reference, the front-back direction is the x-axis, the left-right direction is the y-axis, and the up-down direction is the z-axis; by controlling the knob of the manual displacement platform (8), the platform can be moved along the x-axis, the y-axis and the z-axis; the pressure sensor (7) is installed on the manual displacement platform (8); the nano-displacement platform (6) is installed on the pressure sensor (7); the nano-displacement platform (6) is controlled by the operating platform controller to achieve submicron-level high repeatability and precise positioning; the ultrasonic probe The head tooling (5) is installed on the nano displacement platform (6) through the probe pressure cover tooling 14, the test lower plate (4) is installed on the ultrasonic probe tooling (5), the oil tank (3) is installed on the test lower plate (4), and the test upper plate (2) is installed on the upper beam of the test bench (1), and it is ensured that the boss structure of the test upper plate (2) is directly opposite to the boss structure of the test lower plate (4) and can smoothly enter the oil tank (3); the ultrasonic probe (9) is installed in the ultrasonic probe tooling (5), so that the ultrasonic probe (9) extends from the slide groove on the ultrasonic probe tooling (5) and rests on the test lower plate (4) so that the center of the ultrasonic probe (9) can directly face the boss structure of the test lower plate (4), and the ultrasonic probe (9) provides pre-tightening force through the spring (10) and the probe tooling pressure cover (14); the ultrasonic probe (9) is connected to the oscilloscope, and the host computer is respectively connected to the oscilloscope and the platform controller, and the reading of the oscilloscope data and the operation of the platform controller are realized by operating the host computer; S2, empty the oil tank (3), ensure that the test lower plate (4) is in direct contact with the air, record the echo signal P0 of the ultrasonic probe (9) at this time, perform Fourier transform on the echo signal P0, extract the Fourier transform result corresponding to the center frequency and calculate its absolute value as I0, and save it to the host computer, and record the ultrasonic echo peak value vpp0 displayed on the oscilloscope at this time; S3. Preliminarily ensure that the upper test plate (2) and the lower test plate (4) are aligned by controlling the manual displacement platform (8), so that the eccentricity of the boss center of the upper test plate (2) and the lower test plate (4) does not exceed -2mm to +2mm, and then control the manual displacement platform (8) to gradually raise the lower test plate (4) closer to the upper test plate (2) until the peak value vpp1 of the ultrasonic probe (9) echo displayed on the oscilloscope decreases by 15% to 25% compared with the peak value vpp0 of the ultrasonic echo; S4, by controlling the manual displacement platform (8), the test lower plate (4) is made to reciprocate relative to the test upper plate (2) on the x-axis and y-axis in units of the minimum division value of the manual displacement platform (8), and the movement range of the x-axis and y-axis is -3mm to +3mm, and the x-axis and y-axis coordinates of the manual displacement platform (8) and the echo signal of the ultrasonic probe (9) are recorded after each movement; the x-axis and y-axis coordinates at which the peak-to-peak value of the echo signal of the ultrasonic probe (9) is minimized are found; the manual displacement platform (8) is adjusted to be at the above coordinates and the x-axis and y-axis of the manual displacement platform (8) are locked to prevent subsequent operations from changing the relative position of the test upper plate (2) and the test lower plate (4) so that the ultrasonic probe (9) cannot face the minimum oil film thickness of the friction pair; S5. By controlling the manual displacement platform (8), the test lower plate (4) is continuously moved closer to the test upper plate (2) until the pressure sensor (7) reads 2N. At this time, the test lower plate (4) is in close contact with the test upper plate (2) and the load is 2N. S6, by controlling the nano displacement platform (6) to gradually move the test lower plate (4) away from the test upper plate (2) in units of 1 μm until the pressure sensor (7) reads 0.2N; further controlling the nano displacement platform (6) to gradually move the test lower plate (4) away from the test upper plate (2) in units of 0.05 μm until the pressure sensor (7) reads just 0N, at which point the position of the test lower plate (4) is considered to be the zero position of the oil film thickness; S7, recording the echo signal P1 of the ultrasonic probe (9) at zero position, then controlling the nano displacement platform (6) to gradually move the test lower plate (4) away from the test upper plate (2) in units of 0.5 μm, and recording the echo signal P1 of the ultrasonic probe (9) after each change in the distance between the test lower plate (4) and the test upper plate (2). n and the distance h between the test lower plate (4) and the test upper plate (2) n , for the echo signal P n Perform Fourier transform, extract the center frequency and calculate the absolute value of the result, which is recorded as I n , will be saved to the host computer; S8, the result after Fourier transformation of each echo of the ultrasonic probe (9) I n Substitute into the reflection coefficient calculation formula R n =I n / I0, get the distance h between the upper test plate (2) and the lower test plate (4) n The corresponding ultrasonic reflection coefficient is substituted into the calibration formula as follows: Using nonlinear least squares method to estimate R'n and h n The nonlinear least squares calibration curve is recorded as Complete the calibration of oil film thickness.

2. The minimum oil film thickness calibration method according to claim 1, characterized in that: During the actual test after the calibration is completed, a probe hole (12) is first provided on the bearing seat (13), and then the ultrasonic probe (9) is installed above the cylindrical roller bearing (11) to be tested in a non-lubricated state, and the echo of the ultrasonic probe (9) is recorded as A0; Then, the test is carried out under the lubrication condition to be tested, and the echo of the ultrasonic probe (9) is recorded as A n ; A0 and A n Substitute the reflection coefficient calculation formula to obtain the reflection coefficient R An =A n / A0, the reflection coefficient R An Substitute the calibration formula to obtain the ultrasonic calibration reflection coefficient under the lubrication state to be measured: Then the ultrasonic calibration reflection coefficient R′ An Substitute it into the nonlinear least squares calibration curve to obtain the minimum oil film thickness under the current lubrication state to be measured 3. The minimum oil film thickness calibration method according to claim 1, characterized in that: The bearing is a cylindrical roller bearing 11. The test upper plate (2) and the test lower plate (4) are structurally designed according to the friction pair structure of the cylindrical roller bearing 11. The test upper plate (2) is simplified from the cylindrical roller (11a) structure, and its boss width is 8 mm. The test lower plate (4) is simplified from the cylindrical roller bearing outer ring (11b) structure, and its boss diameter is 8 mm.

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