Rapid test method for frictional wear performance of shaft-bearing bush part

Abstract

The invention relates to a shaft-bearing bush part friction wear performance rapid test method, which utilizes a shaft-bearing bush friction wear testing machine to carry out experiments, adopts a finished product bearing bush in practical application, and uses a straight shaft to simulate a crankshaft journal, and the material and the surface treatment process of the straight shaft are consistent with those of the crankshaft journal. The test is carried out under the conditions of low speed (1-500rpm) and heavy load (5-120MPa), so that the shaft-bearing bush can relatively slide in a boundary lubrication or mixed lubrication state, rapid and stable wear is realized, and the method can rapidly evaluate the friction wear performance of the shaft-bearing bush at the part test level. The device has high flexibility, and shafts and bearing bushes of different materials, different sizes and different surface treatment processes can be replaced according to different requirements. The test result can be quickly obtained, the stability and repeatability are good, and a reliable method is provided for testing the friction and wear performance of the shaft-bearing bush. The application of the method can enhance the performance analysis and optimization of the shaft-bearing bush system.

Description

Technical Field

[0001] The invention relates to a friction and wear performance test method, in particular to a rapid test method for the friction and wear performance of shaft-bearing bush parts, and belongs to the technical field of shaft-bearing bush friction and wear test. Background Art

[0002] The crankshaft-bearing is one of the key matching parts in the internal combustion engine. Under ideal working conditions, a complete lubricating oil film will be formed between the crankshaft and the bearing, which is in a state of fluid dynamic lubrication, thus avoiding direct contact and wear between the shaft and the bearing. Usually, the wear of the bearing mainly occurs under low-speed and heavy-load conditions. When the internal combustion engine starts and stops frequently, the load is too large, the speed is low, or the lubricating oil fails to form a complete oil film, the shaft-bearing is in a state of boundary lubrication or mixed lubrication, which will cause wear between the crankshaft and the bearing, thereby affecting the life of the bearing.

[0003] At present, experts and scholars at home and abroad have carried out research on crankshaft-bearing friction and wear, but there are also some problems: most scholars use bearing materials to make samples or cut blocks from bearings. The friction and wear test of this material level is widely used due to its simple operation and low cost, but its results have certain deviations from the actual working conditions, and it is difficult to fully reflect the performance under real working conditions. Component-level tests usually use "sapphire" bearing friction and wear testers for high-speed wear, but the "sapphire" tester has a complex structure and puts forward high requirements on the performance and accuracy of the test equipment. At the same time, it uses standard bearing samples for testing, which has certain deviations from the actual bearings. Although bench-level tests can provide more detailed and comprehensive experimental data, the test cycle is long and the cost is high, and it is not conducive to discovering friction and wear problems.

[0004] The present invention proposes a rapid test method for the friction and wear performance of bearing parts, and adopts a shaft-bearing friction and wear testing machine to conduct the test. In the test, a finished bearing used in actual application is used, and a simulated straight shaft is used to replace the crankshaft journal, and the size, material and surface process of the straight shaft are consistent with the crankshaft journal. The testing machine can adjust the working conditions such as load, speed, temperature and lubricating oil pressure, and realize the rapid wear of the bearing under the state of boundary lubrication or mixed lubrication. The method has the advantages of short test cycle, reliable results and is conducive to verifying the matching of shaft and bearing, and can provide a basis and reference for the design of bearing and optimization of process parameters. Summary of the invention

[0005] The present invention aims to provide a test method that can quickly and accurately evaluate the friction and wear performance of shaft-bearing shells. During the frequent start-stop of the crankshaft and bearing shells of an internal combustion engine, bearing shell wear often occurs. However, the friction and wear performance of different shaft-bearing shell combinations is difficult to effectively measure by traditional methods. Therefore, the test method of the present invention can quickly and accurately evaluate the friction and wear performance of shaft-bearing shells in mixed lubrication or boundary lubrication conditions. This method has the advantages of easy operation, low cost, and the ability to quickly and accurately evaluate the friction and wear performance of shaft-bearing shells.

[0006] The technical solution of the present invention is achieved in this way:

[0007] A rapid test method for the friction and wear performance of shaft-bearing parts, using the attached Figure 2 The test is conducted on a shaft-bearing friction and wear testing machine, which includes a heating oil tank, an oil inlet pipe, a test bearing oil inlet valve, a support bearing oil inlet valve, a support bearing seat, a bearing fixture, a pressure head, a hydraulic load, a test bearing, a support bearing, a straight shaft, a coupling, a servo motor, an oil tank, a lubricating oil, an oil return gear pump, an oil return pipe, and an oil inlet gear pump. The method is characterized in that the shaft-bearing slides relative to each other under boundary lubrication or mixed lubrication conditions under low-speed and heavy-load test conditions to achieve rapid and stable wear, and includes the following steps:

[0008] Step 1: After cleaning the test bearing, weigh the initial mass of the bearing (m1), measure the initial thickness of the bearing before the test (h1) with a high-precision micrometer, and measure the arithmetic mean deviation of the straight shaft surface profile (Ra1) with a roughness meter;

[0009] Step 2: Install the test bearing in the connecting rod fixture;

[0010] Step 3: Apply a layer of lubricating oil evenly on the surface of the straight shaft and the test bearing, pass the straight shaft through the connecting rod fixture, and place it on the supporting bearing seat;

[0011] Step 4: Start the heating oil tank and the oil inlet gear pump, open the oil inlet valve, and the lubricating oil lubricates the shaft and bearing through the oil inlet pipe. The lubricating oil flows out of the bearing and enters the oil tank. Start the oil return pump, and the lubricating oil returns to the heating oil tank through the oil return pipe, completing the circulation of the lubricating oil.

[0012] Step 5: Start the servo motor to drive the shaft to rotate, and use the hydraulic loading device to load the shaft and the bearing through the pressure head, so that the shaft and the bearing enter the running-in state;

[0013] Step 6. After sufficient running-in, adjust the speed and load so that the shaft-bearing shell is in a boundary lubrication state or a mixed lubrication state for wear test; the basis for judging the boundary lubrication and mixed lubrication state is to perform the Stribeck curve test, in which the speed is gradually reduced under the condition of fixed load; the lowest point of the friction torque is regarded as a sign of entering the mixed lubrication state, and then select a working condition in the mixed lubrication or boundary lubrication state as the test condition for the wear test;

[0014] Step 7. During the test, collect the friction torque in real time; after the test, remove the bearing, clean it and weigh the mass (m2), thickness (h2) and arithmetic mean deviation (Ra2) of the bearing again, calculate the mass difference (Δm), thickness difference (Δh) and arithmetic mean deviation (ΔRa) of the bearing before and after the test, and analyze the friction coefficient of the shaft-bearing in combination with the friction torque. Δm = m2-m1, Δh = h2-h1, ΔRa = Ra2-Ra1, the mass difference of the bearing before and after the test, the height difference of the coating and the friction coefficient are used to characterize the friction and wear performance of the bearing, and the wear mass, wear thickness, height difference and friction coefficient of the shaft are used to characterize the friction and wear performance of the shaft.

[0015] The invention is characterized in that the whole test process is carried out under low speed (1-500rpm) and heavy load (5-120MPa) conditions, and the shaft-bearing shell is in a state of boundary lubrication or mixed lubrication during the test.

[0016] The invention is characterized in that, during the whole test process, the oil temperature range is set between room temperature and 280°C, and the oil pressure range is set between 0.01 and 1 MPa.

[0017] The invention is characterized in that the wear test time is set between 0.1 and 500 hours.

[0018] The characteristic is that the shaft and bearing shells with different materials, surface treatment processes and diameters can be replaced; the shaft materials include ductile iron, forged steel, alloy steel, the surface treatment processes include quenching, nitriding, electroplating, and the shaft diameter ranges from 10 to 1500mm; the bearing shell materials include lead-based, tin-based, copper-based, aluminum-based, composite materials and polymers, and the bearing shell surface treatment processes include electroplating, physical vapor deposition, chemical vapor deposition and spraying. The bearing shell diameter ranges from 10 to 1500mm, covering different types of bearing shells, including thin-walled shells and thick-walled shells.

[0019] The characteristic is that when evaluating the friction and wear performance of the bearing shell, the friction coefficient, wear mass and wear thickness are used together to characterize the friction and wear performance of the bearing shell.

[0020] The characteristic is that when evaluating the friction and wear performance of the shaft, the friction coefficient, the wear mass and wear thickness of the bearing shell and the profile height difference of the shaft are used together to characterize the friction and wear performance of the shaft.

[0021] The method is characterized in that it is also applicable to friction and wear tests of piston pin-bushing and other shaft-sleeve parts.

[0022] Compared with the prior art, the advantages of the present invention are obvious, mainly manifested in:

[0023] 1. Realistic simulation: The friction and wear test method proposed in the present invention uses finished bearings and straight shafts as research objects. The bearings used are bearings currently in service in actual internal combustion engines, and the straight shafts use the same material and size as the crankshaft journals of internal combustion engines. In terms of simulation criteria, based on the same wear mechanism, the wear form of the bearings of internal combustion engines under boundary lubrication or mixed lubrication conditions can be simulated at the component level, so that the friction and wear performance of the shaft-bearing can be quickly and accurately evaluated.

[0024] 2. Wide applicability and practicality: This method can also be used to evaluate bearings and shafts of different materials, and has strong practicality. This method can obtain fast, stable and repeatable friction and wear test results. This provides an effective means for evaluating the friction and wear performance of different materials under actual working conditions, and provides guidance and reference for the design and optimization of bearing process parameters.

[0025] 3. Short time and easy operation: The test method of the present invention can complete the test in a relatively short time (3.5 hours at the fastest), thereby saving time costs, and the operation is also very simple.

[0026] In summary, the present invention has significant advantages in terms of realistic simulation, wide applicability, short time and simple operation, and provides an efficient and reliable method for evaluating the friction and wear performance of shaft-bearing shells. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention has attached Figure 3 width.

[0028] Figure 1 It is a flow chart of the rapid test method for friction and wear performance of shaft-bearing bush parts of the present invention;

[0029] Figure 2 It is a structural schematic diagram of the shaft-bearing friction and wear testing machine of the present invention;

[0030] Figure 3 A shaft-bearing friction torque diagram is shown in an embodiment of the present invention.

[0031] In the structure diagram of the shaft-bearing friction and wear testing machine, 1. heating oil tank, 2. oil inlet pipe, 3. test bearing oil inlet valve, 4. support bearing oil inlet valve, 5. support bearing seat, 6. bearing fixture, 7. pressure head, 8. hydraulic loading, 9. test bearing, 10. support bearing, 11. straight shaft, 12. coupling, 13. servo motor, 14. oil tank, 15. lubricating oil, 16. return oil gear pump, 17. return oil pipe, 18. oil inlet gear pump. DETAILED DESCRIPTION

[0032] like Figure 1 , 2 3. A rapid test method for the friction and wear performance of shaft-bearing parts. Figure 2 The shaft-bearing friction and wear testing machine is used for testing, and the shaft-bearing friction and wear testing machine includes a heating oil tank 1, an oil inlet pipe 2, a test bearing oil inlet valve 3, a support bearing oil inlet valve 4, a support bearing seat 5, a bearing fixture 6, a pressure head 7, a hydraulic load 8, a test bearing 9, a support bearing 10, a straight shaft 11, a coupling 12, a servo motor 13, an oil tank 14, lubricating oil 15, an oil return gear pump 16, an oil return pipe 17, and an oil inlet gear pump 18. The method is characterized in that the shaft-bearing is made to slide relative to each other under boundary lubrication or mixed lubrication conditions through low-speed and heavy-load test conditions to achieve rapid and stable wear, and includes the following steps:

[0033] Step 1: After cleaning the test bearing 9, weigh the initial mass of the bearing (m1), measure the initial thickness of the bearing before the test (h1) with a high-precision micrometer, and measure the arithmetic mean deviation (Ra1) of the straight shaft surface profile with a roughness meter;

[0034] Step 2: Install the test bearing 9 in the connecting rod fixture 6;

[0035] Step 3: Apply a layer of lubricating oil evenly on the surface of the straight shaft 11 and the test bearing 9, pass the straight shaft 11 through the connecting rod fixture 6, and place it on the supporting bearing seat 5;

[0036] Step 4: Start the heating oil tank 1 and the oil inlet gear pump 18, open the oil inlet valve 3, and the lubricating oil lubricates the shaft and the bearing through the oil inlet pipe 2. After the lubricating oil comes out of the bearing, it enters the oil tank 14, starts the oil return pump 16, and the lubricating oil returns to the heating oil tank 1 through the oil return pipe 17, completing the circulation of the lubricating oil;

[0037] Step 5: Start the servo motor 13 to drive the shaft to rotate, and use the hydraulic loading device 8 to load the shaft and the bearing through the pressure head 7, so that the shaft and the bearing enter the running-in state;

[0038] Step 6. After sufficient running-in, adjust the speed and load so that the shaft-bearing shell is in a boundary lubrication state or a mixed lubrication state for wear test; the basis for judging the boundary lubrication and mixed lubrication state is to perform the Stribeck curve test, in which the speed is gradually reduced under the condition of fixed load; the lowest point of the friction torque is regarded as a sign of entering the mixed lubrication state, and then select a working condition in the mixed lubrication or boundary lubrication state as the test condition for the wear test;

[0039] Step 7. During the test, collect the friction torque in real time; after the test, remove the bearing, clean it and weigh the mass (m2), thickness (h2) and arithmetic mean deviation (Ra2) of the bearing again, calculate the mass difference (Δm), thickness difference (Δh) and arithmetic mean deviation (ΔRa) of the bearing before and after the test, and analyze the friction coefficient of the shaft-bearing in combination with the friction torque. Δm = m2-m1, Δh = h2-h1, ΔRa = Ra2-Ra1, the mass difference of the bearing before and after the test, the height difference of the coating and the friction coefficient are used to characterize the friction and wear performance of the bearing, and the wear mass, wear thickness, height difference and friction coefficient of the shaft are used to characterize the friction and wear performance of the shaft.

[0040] The invention is characterized in that the whole test process is carried out under low speed (1-500rpm) and heavy load (5-120MPa) conditions, and the shaft-bearing shell is in a state of boundary lubrication or mixed lubrication during the test.

[0041] The invention is characterized in that, during the whole test process, the oil temperature range is set between room temperature and 280°C, and the oil pressure range is set between 0.01 and 1 MPa.

[0042] The invention is characterized in that the wear test time is set between 0.1 and 500 hours.

[0043] The characteristic is that the shaft and bearing shells with different materials, surface treatment processes and diameters can be replaced; the shaft materials include ductile iron, forged steel, alloy steel, the surface treatment processes include quenching, nitriding, electroplating, and the shaft diameter ranges from 10 to 1500mm; the bearing shell materials include lead-based, tin-based, copper-based, aluminum-based, composite materials and polymers, and the bearing shell surface treatment processes include electroplating, physical vapor deposition, chemical vapor deposition and spraying. The bearing shell diameter ranges from 10 to 1500mm, covering different types of bearing shells, including thin-walled shells and thick-walled shells.

[0044] The characteristic is that when evaluating the friction and wear performance of the bearing shell, the friction coefficient, the wear mass and the wear thickness of the bearing shell are used together to characterize the friction and wear performance of the bearing shell.

[0045] The characteristic is that when evaluating the friction and wear performance of the shaft, the friction coefficient, the wear mass and wear thickness of the bearing shell and the profile height difference of the shaft are used together to characterize the friction and wear performance of the shaft.

[0046] The method is characterized in that it is also applicable to friction and wear tests of piston pin-bushing and other shaft-sleeve parts. Specific embodiment:

[0048] In order to promote the localization of bearings, a bearing with an inner diameter of 100 mm produced by a domestic bearing factory was selected for wear testing.

[0049] Step 1: After cleaning the test bearing 9, weigh the initial mass (m1) of the bearing and measure the initial thickness (h1) of the bearing before the test with a high-precision micrometer;

[0050] Step 2: Install the test bearing 9 in the connecting rod fixture (6);

[0051] Step 3: Apply a layer of lubricating oil evenly on the surface of the straight shaft 11 and the test bearing 9, pass the straight shaft 11 through the connecting rod fixture 6, and place it on the supporting bearing seat 5;

[0052] Step 4: Oil pressure is 0.5MPa;

[0053] Step 5: Start the servo motor, test at a lower speed (100 rpm), hydraulically load to the target load (5 MPa) of the running-in stage, and run-in for 0.5 hours;

[0054] Step 6: After the running-in time is reached, increase the load to the target load (30MPa) and allow it to wear for 3 hours under mixed lubrication or boundary lubrication conditions. The test time can be adjusted as needed.

[0055] Step 7: Record and collect the friction torque data during the entire test process, turn off the heating oil tank and motor, remove the load, remove the bearing after the test, clean it, weigh it, measure the wear thickness, and calculate the wear quality difference and thickness difference.

[0056] Attachment Figure 3 From the bearing friction torque diagram shown, it can be seen that the friction torque remains very stable during the running-in period and the stable wear period. When loaded, the shaft-bearing pair enters the boundary lubrication state, and the surface micro-convexities of the shaft and the bearing begin to contact, causing the friction torque to rise rapidly. After a period of testing, the system enters the stable wear stage. In the end, the wear mass difference of the bearing was 4.2 mg and the thickness difference was 2.2 μm.

Claims

1. A method for quickly testing the friction and wear performance of shaft-bearing parts, using the shaft-bearing friction and wear testing machine of Figure 2 for testing, the shaft-bearing friction and wear testing machine comprising a heating oil tank (1), an oil inlet pipe (2), a test bearing oil inlet valve (3), a support bearing oil inlet valve (4), a support bearing seat (5), a bearing fixture (6), a pressure head (7), a hydraulic load (8), a test bearing (9), a support bearing (10), a straight shaft (11), a coupling (12), a servo motor (13), an oil tank (14), lubricating oil (15), an oil return gear pump (16), an oil return pipe (17), and an oil inlet gear pump (18), wherein the method is characterized in that Through the test conditions of low speed and heavy load, the shaft and the bearing are made to slide relative to each other under boundary lubrication or mixed lubrication to achieve fast and stable wear, including the following steps: Step 1: After cleaning the test bearing (9), weigh the initial mass (m1) of the bearing and use a high-precision micrometer to measure the initial thickness (h1) of the bearing before the test, and use a roughness meter to measure the arithmetic mean deviation (Ra1) of the straight shaft surface profile; Step 2: Install the test bearing (9) in the connecting rod fixture (6); Step 3: Apply a layer of lubricating oil evenly on the surface of the straight shaft (11) and the test bearing (9), pass the straight shaft (11) through the connecting rod fixture (6), and place it on the supporting bearing seat (5); Step 4: Start the heating oil tank (1) and the oil inlet gear pump (18), open the oil inlet valve (3), and the lubricating oil lubricates the shaft and the bearing through the oil inlet pipe (2). The lubricating oil flows out of the bearing and enters the oil tank (14), and the oil return pump (16) is started. The lubricating oil returns to the heating oil tank (1) through the oil return pipe (17), completing the circulation of the lubricating oil; Step 5: Start the servo motor (13) to drive the shaft to rotate, and use the hydraulic loading device (8) to load the shaft and the bearing bush through the pressure head (7) so that the shaft and the bearing bush enter a running-in state; Step 6. After sufficient running-in, adjust the speed and load so that the shaft-bearing shell is in a boundary lubrication state or a mixed lubrication state for wear test; the basis for judging the boundary lubrication and mixed lubrication state is to perform the Stribeck curve test, in which the speed is gradually reduced under the condition of fixed load; the lowest point of the friction torque is regarded as a sign of entering the mixed lubrication state, and then select a working condition in the mixed lubrication or boundary lubrication state as the test condition for the wear test; Step 7. During the test, collect the friction torque in real time; after the test, remove the bearing, clean it and weigh the bearing mass (m2), thickness (h2) and the arithmetic mean deviation of the shaft profile (Ra2) again. Calculate the mass difference (Δm), thickness difference (Δh) and arithmetic mean deviation of the shaft profile (ΔRa) of the bearing before and after the test, and analyze the friction coefficient of the shaft-bearing in combination with the friction torque. Δm = m2-m1, Δh = h2-h1, ΔRa = Ra2-Ra1, the mass difference of the bearing before and after the test, the height difference of the coating and the friction coefficient are used to characterize the friction and wear performance of the bearing, and the wear mass, wear thickness, height difference of the shaft profile and the friction coefficient are used to characterize the friction and wear performance of the shaft.

2. The rapid test method for friction and wear performance of shaft-bearing parts according to claim 1 is characterized in that: The entire test process is carried out under low speed (1-500rpm) and heavy load (5-120MPa) conditions. During the test, the shaft-bearing shell is in a state of boundary lubrication or mixed lubrication.

3. The rapid test method for friction and wear performance of shaft-bearing parts according to claim 1 is characterized in that: During the entire test process, the oil temperature range was set between room temperature and 280°C, and the oil pressure range was set between 0.01 and 1 MPa.

4. The rapid test method for friction and wear performance of shaft-bearing parts according to claim 1 is characterized in that: The wear test time is set between 0.1-500 hours.

5. The rapid test method for friction and wear performance of shaft-bearing parts according to claim 1 is characterized in that: It is also possible to replace shafts and bearings with different materials, surface treatment processes and diameters; shaft materials include ductile iron, forged steel, alloy steel, surface treatment processes include quenching, nitriding, electroplating, and shaft diameters range from 10 to 1500mm; bearing materials include lead-based, tin-based, copper-based, aluminum-based, composite materials and polymers, and bearing surface treatment processes include electroplating, physical vapor deposition, chemical vapor deposition and spraying. The bearing diameter ranges from 10 to 1500mm, covering different types of bearings, including thin-walled bearings and thick-walled bearings.

6. The rapid test method for friction and wear performance of shaft-bearing parts according to claim 1 is characterized in that: When evaluating the friction and wear performance of the bearing, the friction coefficient, the wear mass and the wear thickness of the bearing are used together to characterize the friction and wear performance of the bearing.

7. The rapid test method for friction and wear performance of shaft-bearing parts according to claim 1 is characterized in that: When evaluating the friction and wear performance of the shaft, the friction coefficient, the wear mass and wear thickness of the bearing shell and the profile height difference of the shaft are used together to characterize the friction and wear performance of the shaft.

8. The rapid test method for friction and wear performance of shaft-bearing parts according to claim 1 is characterized in that: This method is also applicable to friction and wear tests of piston pin-bushing and other shaft-sleeve parts.

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