High-temperature high-speed heavy-load thrust bearing testing device and testing method

Abstract

The application discloses a high-temperature high-speed heavy-load thrust bearing testing device and testing method. On the basis of the process of "vacuum degassing-negative pressure oil injection-high temperature pressure maintaining-working condition testing", a monitoring parameter threshold value judgment and feedback adjustment mechanism is introduced. The cabin pressure, bubble signal, dynamic torque, vibration value and wear rate are used as the key monitoring parameters reflecting the cavitation risk. The trigger threshold value and target stable interval of each monitoring parameter are established. When any monitoring parameter reaches the preset threshold value, at least one of the vacuum pumping time, oil injection flow rate, heating rate, pressure maintaining time, cooling flow rate, rotating speed loading gradient and load loading gradient is adjusted to make the monitoring parameter fall back and stabilize in the target interval, thereby inhibiting the formation and expansion of cavitation. The application has the advantages of high testing precision, remarkable cavitation prevention and control effect and outstanding creativity.

Description

Technical Field

[0001] This invention relates to the field of testing technology for core components of submersible electric pump protectors, and in particular to a testing device and method for high-temperature, high-speed, heavy-load thrust bearings. Background Technology

[0002] Thrust bearings used in submersible electric pump protectors operate under high temperature, high load, and high speed conditions for extended periods, and their performance reliability directly impacts the downhole service life of the submersible electric pump. Common cavitation phenomena during thrust bearing testing can cause repeated impacts on the material surface, fatigue spalling, and accelerated wear, leading to distorted test data.

[0003] Existing anti-cavitation testing methods mostly adopt the approach of "room temperature oil injection - temperature rise test" or "short-time vacuuming + direct loading". Although these methods are common in the field of mechanical testing, they still have problems such as difficulty in completely removing residual air in the chamber, easy air entrainment during the oil injection process, and lack of targeted adjustment during the temperature rise and loading process when facing extreme conditions such as 400℃, 30T, and 12000r / min. As a result, under the combined effect of decreased oil viscosity, release of dissolved gases, and the formation of local low-pressure areas at high temperatures, the bearing surface is still prone to significant cavitation damage.

[0004] Furthermore, traditional methods typically execute vacuuming, oil injection, heating, and loading as fixed steps in sequence, reflecting more of a simple superposition of conventional methods and lacking parameter judgment and processing logic for experimental effects. When monitoring chamber pressure fluctuations, increased bubbles, sudden torque changes, excessive vibration, or abnormal wear rates, existing methods often only issue alarms and cannot form a closed-loop control to restore key monitoring parameters to a reasonable range, thus lacking creative expression.

[0005] Therefore, there is an urgent need to provide a process that not only features a coordinated workflow of "vacuuming—high-temperature oil—high-temperature testing," but also enables threshold determination, feedback adjustment, and range stability control of key parameters based on experimental results. This would reduce cavitation damage, improve test consistency, and highlight the technological innovation of the solution. Summary of the Invention

[0006] This invention aims to provide a testing device and method for high-temperature, high-speed, heavy-load thrust bearings. Based on the basic process of "vacuum degassing - negative pressure oil injection - high-temperature pressure holding - working condition testing", it introduces a monitoring parameter threshold judgment and feedback adjustment mechanism, so that the process is no longer limited to a fixed process combination, but can take corresponding treatment measures according to the actual effect in the experimental process.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] This invention discloses a high-temperature, high-speed, heavy-load thrust bearing testing device, including a testing chamber, a clamping device, and a sealing device;

[0009] The test chamber includes a housing cavity and a monitoring system. The outer surface of the housing cavity is equipped with a cooling component and a heating component. The housing cavity is located inside the outer shell. A multi-layer heat insulation device is provided between the outer shell and the housing cavity. The housing cavity is equipped with a pressurization component, which includes a hydraulic cylinder and a clamping base coaxially arranged at both ends of the housing cavity.

[0010] The clamping device includes a base and a clamp. The outer end of the base is provided with a hydraulic locking device, which is adapted to a hydraulic cylinder. The outer end of the clamp is provided with a connecting rod, which is adapted to the clamping base.

[0011] The sealing device includes a sealing collar, a CF sealing flange is installed on the end face of the sealing collar, a sliding sealing cavity is formed between the sealing collar and the CF sealing flange, a lubrication channel is provided on the inner wall of the sealing flange, and the sealing device is located between the receiving cavity and the hydraulic cylinder.

[0012] Preferably, the lubrication channel is connected to a one-way valve.

[0013] Preferably, the sealing ring is formed by fitting and fixing an Al2O+TiC self-lubricating ceramic matrix composite ring and an Inconel 718 elastic compensation ring together.

[0014] Preferably, the material for the multi-layer insulation device is thermal insulation cotton.

[0015] Preferably, the cooling component is a water-cooled heat exchange tube or heat exchanger, and the heating component is an electric heater.

[0016] Preferably, the base is provided with a positioning pin hole for quick connection with the test chamber.

[0017] Preferably, the monitoring system includes a temperature sensor, a pressure sensor, a speed sensor, and a vibration sensor.

[0018] Preferably, the linkage control system is based on a Siemens S7-200 PLC, connected to a monitoring system, namely temperature sensors, pressure sensors, speed sensors, vibration sensors, and various actuators, to achieve multi-parameter linkage control.

[0019] The present invention also discloses a testing method using the above-described apparatus, comprising the following steps:

[0020] S1. Preparation before testing: Fix the thrust bearing with an adjustable clamp of φ80~φ130mm, complete the vacuum system leakage test, and preheat the high temperature oil to 150℃.

[0021] S2, Vacuum degassing: First, reduce the pressure in the test chamber to 50 Pa and maintain it for 10 min, then reduce it to less than 10 Pa and maintain it for 30 min;

[0022] S3. Negative pressure oil injection: Under negative pressure conditions in the test chamber, inject 15~25L of high-temperature oil into the test chamber at a flow rate of no more than 5L / min, and then stir to remove gas and let it stand to remove foam.

[0023] S4. High temperature pressure holding and working condition test: The high temperature oil is heated to 400℃ at 5℃ / min. Gas is introduced into the test chamber to raise the pressure to 0.1MPa and hold the pressure for 10min. Then, the thrust bearing is subjected to a speed of 12000r / min and an axial load of 30T. Dynamic torque, vibration and wear are collected simultaneously.

[0024] S5. Feedback Adjustment: Using chamber pressure, bubble signal, dynamic torque, vibration value, and wear rate as monitoring parameters, when any monitoring parameter reaches its corresponding threshold, at least one of the following is dynamically adjusted: vacuuming time, oil injection flow rate, heating rate, pressure holding time, cooling flow rate, rotational speed loading gradient, and load loading gradient, so that the corresponding monitoring parameter recovers and stabilizes within a preset range. A cavitation risk index R is constructed as a comprehensive judgment quantity, and its expression is:

[0025]

[0026] in This represents the absolute value of the cabin pressure deviating from the set value. The number of times the light signal is reflected by the bubble. This refers to the dynamic torque mutation. The vibration value, This represents the abrupt change in wear rate. , , , , Weighting coefficients that are greater than 0

[0027] When R < 1, it is determined to be in the stable zone; when 1 ≤ R < 1.5, it is determined to be in the adjustable zone and a first-level adjustment is performed; when R ≥ 1.5, it is determined to be in the high-risk zone and a second-level adjustment is performed or the test is suspended.

[0028] S6. Post-processing: unloading, cooling, oil recovery, and testing of bearing cavitation damage rate.

[0029] Preferably, the adjustable fixture is made of GH4169 material. The adjustable fixture is connected to the H7 tolerance hole of the test chamber through a conical locating pin. The inner side of the conical locating pin is coated with MoS2 base coating. The coefficient of friction is not greater than 0.08 at 400℃. The coaxiality between the fixture and the test chamber is not greater than 0.03mm.

[0030] Preferably, the vacuum system includes a ZJ~40 type main vacuum pump and a Roots vacuum pump, with an ultimate vacuum degree of no more than 0.1 Pa. A 50 mm thick ceramic fiber heat insulation layer is installed on the outside of the test chamber to ensure that the temperature uniformity inside the test chamber is no more than 2 °C.

[0031] Preferably, the kinematic viscosity of the high-temperature oil at 40°C is 28 mm. 2 / s, flash point not lower than 280℃; when filling with oil, the oil level should be 8~12mm higher than the upper surface of the bearing.

[0032] Preferably, in step S3, if the pressure inside the tank is greater than 15Pa during oil injection, oil injection is paused and vacuuming is continued for 5-10 minutes until the pressure inside the tank returns to below 10Pa before oil injection continues.

[0033] Preferably, in step S3, when the bubble reflection light signal during the oil degassing stage is greater than 5 times / s, the vacuuming time is extended by 10 to 20 minutes, and the stirring speed is reduced by 10% to 30% until the bubble reflection light signal recovers to below 5 times / s.

[0034] Preferably, in step S5, when the dynamic torque fluctuation exceeds 5 N·m, the speed loading gradient and / or load loading gradient are reduced, and the pressure holding time is extended by 5 to 10 minutes until the dynamic torque fluctuation amplitude recovers to within ±10% of the reference torque value.

[0035] Preferably, in step S5, when the vibration value is greater than 1g and lasts for more than 2s, the flow rate of the oil cooling system is increased by 10% to 20%, and the heating rate is reduced from 5℃ / min to 2 to 3℃ / min until the vibration value drops below 1g.

[0036] Preferably, in step S5, when the sudden change in wear rate is greater than 5 μm / h, the speed or load should be stopped from being increased further, and the current working condition should be maintained for 5 to 10 minutes until the wear rate recovers and stabilizes before continuing the test.

[0037] Preferably, the preset range in step S5 includes the following parameters: chamber pressure less than 10 Pa, bubble reflection light signal less than 5 times / s, vibration value less than 1 g, wear rate mutation less than 5 μm / h, and dynamic torque fluctuation amplitude not exceeding ±10% of the reference torque value.

[0038] The beneficial effects of this invention are:

[0039] This invention elevates the originally static testing process to a dynamic closed-loop control method based on experimental results, making it particularly suitable for cavitation testing of thrust bearings under high temperature, heavy load, and high-speed coupling conditions. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the present invention;

[0041] Figure 2 This is a top view of the present invention;

[0042] Figure 3 for Figure 2 A cross-sectional view along BB;

[0043] Figure 4 This is a schematic diagram of the clamping device.

[0044] Figure 5 This is a top view of the sealing device;

[0045] Figure 6 for Figure 5 A sectional view along AA;

[0046] Figure 7 This is a flowchart of the present invention.

[0047] In the diagram: 11-accommodating cavity, 12-cooling component, 13-heating component, 14-outer shell, 15-multi-layer heat insulation device, 16-hydraulic cylinder, 17-clamping base, 21-base, 22-clamp, 23-hydraulic locking device, 24-connecting rod, 25-positioning pin hole, 31-sealing collar, 32-CF sealing flange, 33-sliding sealing cavity, 34-lubrication channel, 4-thrust bearing. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings.

[0049] The steps of this invention include six stages: pre-test preparation, vacuum degassing, high-temperature oil negative pressure filling, high-temperature pressure holding and working condition testing, feedback adjustment, and post-processing. Compared with existing solutions, its key difference is that during high-temperature testing and loading, not only is monitoring carried out, but corresponding processing measures are also triggered based on the monitoring results to achieve parameter stabilization.

[0050] like Figures 1-6 As shown, this invention discloses a high-temperature, high-speed, heavy-load thrust bearing testing device, including a testing chamber, a clamping device, and a sealing device.

[0051] The test chamber includes a housing cavity 11 and a monitoring system. The outer surface of the housing cavity 11 is provided with a cooling component 12 and a heating component 13. The housing cavity 11 is located inside the outer shell 14. A multi-layer heat insulation device 15 is provided between the outer shell 14 and the housing cavity 11. The material of the multi-layer heat insulation device 15 is heat insulation cotton. The housing cavity 11 is provided with a pressurization component, which includes a hydraulic cylinder 16 and a clamping base 17 coaxially arranged at both ends of the housing cavity 11.

[0052] The clamping device includes a base 21 and a clamp 22. The outer end of the base 21 is provided with a hydraulic locking device 23, which is adapted to a hydraulic cylinder 16. The outer end of the clamp 22 is provided with a connecting rod 24, which is adapted to a clamping base 17. The base 21 is provided with a positioning pin hole 25, which is used for quick connection with the test chamber. The coaxiality of the docking is ≤0.03mm, and the clamping time is ≤5 minutes.

[0053] The sealing device includes a sealing ring 31, which is formed by fitting and fixing an Al2O+TiC self-lubricating ceramic matrix composite ring and an Inconel 718 elastic compensation ring. A CF sealing flange 32 is installed on the end face of the sealing ring 31, and a sliding sealing cavity 33 is formed between the sealing ring 31 and the CF sealing flange 32. A lubrication channel 34 is provided on the inner wall of the sealing flange, and the lubrication channel 34 is connected to a one-way valve. The sealing device is located between the receiving cavity 11 and the hydraulic cylinder 16.

[0054] Cooling component 12 is a water-cooled heat exchange tube and heat exchanger;

[0055] Heating component 13 is an electric heater, i.e. a heating plate, with a rated power of 10KW, a heating range of room temperature to 400℃, a maximum heating temperature of 500℃, and a heating rate of ≥5℃ / min.

[0056] The outer casing 14 is made of 304 stainless steel;

[0057] The dimensions of cavity 11 are φ300mm × 800mm;

[0058] The base 21 is made of 304 stainless steel and has a load-bearing capacity of >30T;

[0059] There are 2 to 3 sets of fixture 22 in actual working conditions, which are compatible with thrust bearings of series 338, 387, 456, 540, 562 and 675.

[0060] The monitoring system includes temperature sensors, pressure sensors, speed sensors, and vibration sensors. The linkage control system is based on a Siemens S7-200 PLC, which connects the monitoring system and various actuators to achieve multi-parameter linkage control.

[0061] like Figure 7 As shown, the present invention also discloses a testing method using the above-described device, specifically including the following steps:

[0062] I. Pre-test preparation stage

[0063] (1) Bearing clamping and fixture adjustment: The thrust bearing 4 to be tested is installed in the clamping device. The fixture 22 is made of GH4169 high temperature alloy. The spacing of the positioning blocks is adjusted by three sets of radial fine adjustment screws to achieve the adaptation of bearings of different specifications within the range of φ80~φ130mm. The bottom of the clamping device is engaged with the positioning hole of the test chamber base through a conical positioning pin. The hydraulic locking device is pressurized to 36T to ensure that the coaxiality between the fixture 22 and the test chamber is not greater than 0.03mm;

[0064] (2) Vacuum system and sealing inspection: Start the vacuum system and close the test chamber valve, and conduct a 30-minute leakage test; if the vacuum level increases from less than 10 Pa to more than 12 Pa, the seal is deemed to be in failure and the sliding seal is replaced. The sliding seal is preferably a combination structure of Al2O3+TiC ceramic matrix composite sealing layer and Inconel 718 elastic compensation ring.

[0065] (3) Preparation of high temperature oil and oil injection system: Select SY-400 type high temperature oil, inject it into the preheating tank with electric heating device, heat it to 150℃ and control the temperature difference within ±1℃ to reduce gas evolution and temperature difference entrapment caused by low temperature oil injection.

[0066] II. Vacuum Degassing Stage

[0067] (1) Primary vacuuming: Turn on the main vacuum pump and reduce the pressure inside the chamber from atmospheric pressure to 50 Pa at a rate of 5 Pa / min, maintain for 10 min, and at the same time heat the chamber wall to 80°C to reduce the adsorption of gas on the chamber wall surface.

[0068] (2) Deep vacuuming: Switch the Roots vacuum pump to work in series with the main vacuum pump to further reduce the vacuum level in the chamber to less than 10 Pa and maintain it for 30 min. Cover the outside of the test chamber with a ceramic fiber insulation layer with a thickness of 50 mm, control the temperature of the outer wall of the chamber to not exceed 50℃, and use three sets of distributed temperature sensors to ensure that the temperature uniformity inside the chamber is not greater than 2℃.

[0069] III. High-Temperature Oil Negative Pressure Filling Stage

[0070] (1) Negative pressure oil injection: Open the oil injection valve and use the negative pressure of less than 10Pa in the chamber to draw the preheated high temperature oil into the test chamber. The oil injection flow rate is controlled to be no more than 5L / min, and the oil injection volume is adjusted to 15~25L according to the bearing specifications. The oil level is 8~12mm higher than the upper surface of the bearing.

[0071] (2) Secondary degassing of oil: After the oil injection is completed, maintain the vacuum degree in the chamber less than 10Pa, start the micro stirrer to stir at 500r / min for 10min, and then let it stand for 5min; if the reflected light signal of the bubble is still higher than the threshold, continue to perform supplementary vacuuming and reduce stirring intensity.

[0072] IV. High Temperature Pressure Holding and Operating Condition Testing Phase

[0073] (1) Heating and temperature control: Start the heating system to raise the oil temperature from 150°C to 400°C at 5°C / min; simultaneously start the oil cooling system to control the temperature of the bulkhead and hydraulic cylinder end not to exceed 60°C;

[0074] (2) High temperature pressure holding: After the oil reaches 400℃, nitrogen is introduced to raise the pressure inside the tank to 0.1MPa and hold the pressure for 10 minutes to allow the residual tiny bubbles in the oil to escape further.

[0075] (3) Loading and monitoring: The rotational speed was increased from 1500 r / min to 12000 r / min in increments of 1000 r / min, with each increment stabilizing for 5 minutes; subsequently, the load was increased from 0 T to 30 T in increments of 2 T / min.

[0076] During the test, dynamic torque, vibration, wear, chamber pressure, and bubble signals are collected simultaneously to provide a basis for subsequent feedback and adjustment.

[0077] V. Feedback Adjustment Rules

[0078] To highlight the closed-loop control feature of this invention, the processing rule of "monitoring parameters - trigger threshold - processing measures - target range" shown in Table 1 is preferred.

[0079]

[0080] Table 1 Closed-loop control processing rules

[0081] VI. Post-processing stage

[0082] After the test, the following steps were performed: first unload the load, then reduce the speed, and then cool down the engine. The load was reduced from 30T to 0T at a rate of 5T / min, the speed was reduced from 12000r / min to 1500r / min and stabilized for 5 minutes before being reduced to 0r / min. Then, the oil temperature was reduced to below 150℃ through the oil cooling system.

[0083] Open the drain valve to discharge the high-temperature oil into the recovery system. After passing through a three-stage filtration process of 50μm→20μm→10μm, the oil is reused, with an oil regeneration rate of no less than 80%. After the temperature inside the chamber drops below 80℃, remove the bearing sample and test the cavitation damage rate on the bearing surface using a wear testing system. A damage area of ​​no more than 0.5% is considered acceptable.

[0084] Example 1: Test 4 of 338 series thrust bearing

[0085] Clamp the 338 series bearing and adjust the coaxiality of the clamping device to 0.02mm. After a 30-minute vacuum system leak test, the vacuum level stabilizes at 8Pa. Preheat the SY-400 high-temperature oil to 150℃, perform a primary vacuum to 50Pa and maintain it for 10 minutes, followed by a deep vacuum to 8Pa and maintain it for 30 minutes.

[0086] 15L of high-temperature oil was injected at a flow rate of 4L / min. After stirring and degassing for 10 minutes, no abnormal bubble signals were detected. The temperature was then increased to 400℃ at a rate of 5℃ / min, and the bulkhead temperature was controlled at 55℃. When loaded to 12000r / min and 30T, the dynamic torque stabilized at 45N·m, the vibration value was 0.6g, and the wear rate was 2μm / h, all within the target range, and no secondary regulation was required.

[0087] After the test, the temperature was lowered to 140℃, and 14.8L of oil was recovered, with a recovery rate of 98.7%. The bearing cavitation damage area accounted for 0.3%, and the test results were qualified.

[0088] Example 2: Test 4 of 675 series thrust bearing

[0089] Clamp the 675 series bearing and control the coaxiality of the clamping device to 0.03mm. After the vacuum system leakage test, the vacuum degree stabilizes at 9Pa. Preheat the high temperature oil to 150℃, then evacuate to 9Pa and maintain it for 30min.

[0090] 25L of high-temperature oil was injected at a flow rate of 5L / min, and the mixture was stirred and degassed for 10 minutes. After heating to 400℃ and loading to 12000r / min and 30T, the dynamic torque was monitored to be 52N·m, the vibration value was 0.7g, and the wear rate was 3μm / h. All of these values ​​did not exceed the preset thresholds, and the system maintained stable operation.

[0091] After the test, 24.5L of oil was recovered, with a recovery rate of 98%, and the bearing cavitation damage area accounted for 0.4%, verifying the applicability of the present invention on large-size thrust bearing 4.

[0092] Beneficial effects

[0093] 1. Significant effect in cavitation control. Through the synergistic process of "30min deep vacuuming (<10Pa) + negative pressure oil injection + high temperature pressure holding + closed-loop parameter adjustment", the residual air in the test system can be controlled to below 0.1%, reducing the cavitation damage rate from 20% of the traditional process to below 0.5%.

[0094] 2. High accuracy of test data. Through real-time monitoring and threshold trigger adjustment of chamber pressure, bubbles, torque, vibration and wear, the abnormal operating condition identification rate can reach over 95%, and the test data deviation can be controlled within 3%.

[0095] 3. More complete creative expression. This invention does not simply superimpose common mechanical methods such as vacuuming, oil injection, heating, and loading, but establishes parameter judgment, processing rules, and stable range control logic based on experimental results. It can proactively take corresponding measures to restore stability to the test process when parameters are abnormal, thus forming a closed-loop control scheme with clear technical logic.

[0096] 4. Excellent multi-series compatibility and cost-effectiveness. Utilizing an adjustable clamping device (φ80~φ130mm) and dynamic oil injection control, it is compatible with the entire 338~675 series of thrust bearings. Process changeover time is less than 30 minutes, and single-batch testing costs are reduced by 35%.

[0097] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims.

Claims

1. A testing device for high-temperature, high-speed, heavy-load thrust bearings, characterized in that: Includes test chamber, clamping device, and sealing device; The test chamber includes a housing cavity (11) and a monitoring system. The outer surface of the housing cavity (11) is provided with a cooling component (12) and a heating component (13). The housing cavity (11) is located inside the outer shell (14). A multi-layer heat insulation device (15) is provided between the outer shell (14) and the housing cavity (11). The housing cavity (11) is provided with a pressurization component, which includes a hydraulic cylinder (16) and a clamping base (17) coaxially arranged at both ends of the housing cavity (11). The clamping device includes a base (21) and a clamp (22). The outer end of the base (21) is provided with a hydraulic locking device (23), which is adapted to a hydraulic cylinder (16). The outer end of the clamp (22) is provided with a connecting rod (24), which is adapted to a clamping base (17). The sealing device includes a sealing collar (31), a CF sealing flange (32) is installed on the end face of the sealing collar (31), a sliding sealing cavity (33) is formed between the sealing collar (31) and the CF sealing flange (32), a lubrication channel (34) is provided on the inner wall of the sealing flange, and the sealing device is located between the receiving cavity (11) and the hydraulic cylinder (16).

2. A testing method using the testing apparatus of claim 1, characterized in that... Includes the following steps: S1. Preparation before testing: Fix the thrust bearing with an adjustable clamp, complete the vacuum system leakage test, and preheat the high-temperature oil to 150°C. S2, Vacuum degassing: First, reduce the pressure in the test chamber to 50 Pa and maintain it for 10 min, then reduce it to less than 10 Pa and maintain it for 30 min; S3. Negative pressure oil injection: Under negative pressure conditions in the test chamber, inject 15~25L of high-temperature oil into the test chamber at a flow rate of no more than 5L / min, and then stir to remove gas and let it stand to remove foam. S4. High temperature pressure holding and working condition test: The high temperature oil is heated to 400℃ at 5℃ / min. Gas is introduced into the test chamber to raise the pressure to 0.1MPa and hold the pressure for 10min. Then, the thrust bearing is subjected to a speed of 12000r / min and an axial load of 30T. Dynamic torque, vibration and wear are collected simultaneously. S5. Feedback Adjustment: Using chamber pressure, bubble signal, dynamic torque, vibration value, and wear rate as monitoring parameters, when any monitoring parameter reaches its corresponding threshold, at least one of the following is dynamically adjusted: vacuuming time, oil injection flow rate, heating rate, pressure holding time, cooling flow rate, rotational speed loading gradient, and load loading gradient, so that the corresponding monitoring parameter recovers and stabilizes within a preset range. A cavitation risk index R is constructed as a comprehensive judgment quantity, and its expression is: ； in This represents the absolute value of the cabin pressure deviating from the set value. The number of times the light signal is reflected by the bubble. This refers to the dynamic torque mutation. The vibration value, This represents the abrupt change in wear rate. , , , , Weighting coefficients that are greater than 0 When R < 1, it is determined to be in the stable zone; when 1 ≤ R < 1.5, it is determined to be in the adjustable zone and a first-level adjustment is performed; when R ≥ 1.5, it is determined to be in the high-risk zone and a second-level adjustment is performed or the test is suspended. S6. Post-processing: unloading, cooling, oil recovery, and testing of bearing cavitation damage rate.

3. The test method according to claim 2, characterized in that: The adjustable fixture is made of GH4169 material. The adjustable fixture is connected to the H7 tolerance hole of the test chamber through a conical locating pin. The inner side of the conical locating pin is coated with MoS2 base coating. The coefficient of friction is not greater than 0.08 at 400℃. The coaxiality between the fixture and the test chamber is not greater than 0.03mm.

4. The test method according to claim 2, characterized in that: The vacuum system includes a ZJ~40 main vacuum pump and a Roots vacuum pump, with an ultimate vacuum of no more than 0.1 Pa. A 50 mm thick ceramic fiber insulation layer is installed on the outside of the test chamber to ensure that the temperature uniformity inside the test chamber is no more than 2 °C.

5. The test method according to claim 2, characterized in that: The kinematic viscosity of the high-temperature oil at 40℃ is 28 mm. 2 / s, flash point not lower than 280℃; when filling with oil, the oil level should be 8~12mm higher than the upper surface of the bearing.

6. The test method according to claim 2, characterized in that: In step S3, if the pressure inside the tank is greater than 15Pa during oil injection, stop oil injection and continue to evacuate for 5 to 10 minutes until the pressure inside the tank returns to below 10Pa before continuing oil injection.

7. The test method according to claim 2, characterized in that: In step S3, when the bubble reflection light signal during the oil degassing stage is greater than 5 times / s, extend the vacuuming time by 10 to 20 minutes and reduce the stirring speed by 10% to 30% until the bubble reflection light signal recovers to below 5 times / s.

8. The test method according to claim 2, characterized in that: In step S5, when the dynamic torque fluctuation exceeds 5 N·m, reduce the speed loading gradient and / or load loading gradient, and extend the pressure holding time by 5 to 10 minutes until the dynamic torque fluctuation amplitude recovers to within ±10% of the reference torque value.

9. The test method according to claim 2, characterized in that: In step S5, when the vibration value is greater than 1g and lasts for more than 2s, increase the flow rate of the oil cooling system by 10% to 20% and reduce the heating rate from 5℃ / min to 2 to 3℃ / min until the vibration value drops below 1g. In step S5, when the sudden change in wear rate is greater than 5 μm / h, stop increasing the speed or load and maintain the current working condition for 5 to 10 minutes. Continue testing after the wear rate stabilizes.

10. The test method according to claim 2, characterized in that: The preset range in step S5 includes the following parameters: chamber pressure less than 10 Pa, bubble reflection light signal less than 5 times / s, vibration value less than 1 g, wear rate mutation less than 5 μm / h, and dynamic torque fluctuation amplitude not exceeding ±10% of the reference torque value.

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