Method for evaluating service life of lubricating grease for sliding friction pair in high and low temperature environment

Abstract

The invention discloses a method for evaluating the service life of lubricating grease for a sliding friction pair in a high and low temperature environment, which comprises the following steps: a first-stage test: adjusting the lubricating grease at a set temperature, operating the lubricating grease under a rated load to obtain first-stage test data, and judging whether the lubricating grease passes the first-stage test according to the first-stage test data; and if the lubricating grease passes the first-stage test, further performing a second-stage test on the lubricating grease on the basis of the first-stage test: operating under a load higher than a rated load to obtain second-stage test data, and judging the service life grade of the lubricating grease according to the second-stage test data. According to the method for evaluating the service life of the lubricating grease for the sliding friction pair in the high-low temperature environment, the service life of the lubricating grease for the sliding friction pair is tested, the service life testing speed of the lubricating grease for the sliding friction pair is high, evaluation is accurate, and the method can be used in the high-temperature environment and the low-temperature environment; the application range of the lubricating grease life evaluation method is expanded.

Description

Technical Field

[0001] The invention belongs to the technical field of grease life testing, and in particular relates to a method for evaluating the life of grease for sliding friction pairs under high and low temperature environments. Background Art

[0002] Lubricants play an extremely important role in industrial production. They can reduce friction, thereby reducing unnecessary wear and energy loss, and protect mechanical equipment and extend its service life.

[0003] In the related art, the life evaluation of grease is generally carried out at room temperature, and the test is mainly carried out on grease for rolling bearings. There is a lack of rapid and accurate evaluation methods for grease for sliding friction pairs. Summary of the invention

[0004] The purpose of the present invention is to provide a method for evaluating the life of lubricating grease for sliding friction pairs under high and low temperature environments, so as to solve the problem of lack of a rapid and accurate evaluation method for lubricating grease for sliding friction pairs in the prior art.

[0005] To this end, the present invention provides a method for evaluating the life of a lubricating grease for a sliding friction pair under a high and low temperature environment, comprising the following steps: performing a first-stage test on the lubricating grease on a sliding friction pair test bench: adjusting the lubricating grease at a set temperature, operating it under a rated load, obtaining first-stage test data, and judging whether the first-stage test is passed according to the first-stage test data;

[0006] If the first stage test is passed, the grease will be further subjected to a second stage test based on the first stage test: operating at a load higher than the rated load to obtain second stage test data, and the life grade of the grease will be determined based on the second stage test data.

[0007] Preferably, the first stage test data includes the number of friction pair operation times and abnormal noise operation times, the maximum temperature, the friction coefficient and the noise value during operation. Further preferably, it also includes the wear state of the friction pair.

[0008] Preferably, in the first stage test, the number of operations under rated load does not exceed the maximum set number, wherein the last several operation times within the maximum set number range are used as auxiliary determination times.

[0009] Preferably, in the first stage test, if no abnormal sound occurs, or no abnormal sound occurs again after an abnormal sound occurs, or the continuous abnormal sound exceeds a specified number of times, the first stage test is terminated.

[0010] Preferably, the step of judging whether the first stage test is passed according to the first stage test data comprises:

[0011] If the maximum temperature and friction coefficient do not exceed the critical value, the vehicle is judged to have passed the first stage test, and the fewer times of abnormal noise operation, the higher the evaluation level;

[0012] If the high temperature or friction coefficient exceeds the critical value, or the number of operations exceeds the maximum set number of times and there is still abnormal noise, it is judged that the first stage test has not passed.

[0013] Preferably, the second stage test data includes the wear state of the friction pair, the number of times the friction pair operates, the maximum temperature, the friction coefficient, and the value of abnormal noise occurring during operation.

[0014] Preferably, the operation at a load higher than the rated load is operation at 1.05-2 times the rated load.

[0015] Preferably, in the second stage test, if the abnormal noise value, the maximum temperature or the friction coefficient exceeds a critical value, the second stage test is terminated.

[0016] Preferably, in determining the life grade of the grease based on the second-stage test data, when the abnormal noise value, the maximum temperature and the friction coefficient do not exceed the critical value, the more times the operation is performed, the higher the evaluation grade is.

[0017] Preferably, the sliding friction pair test bench is placed in an environmental chamber, and the environmental chamber is used to adjust the ambient temperature of the friction pair test bench when testing the grease.

[0018] Beneficial effects:

[0019] 1. The present invention provides a method for evaluating the life of lubricating grease for sliding friction pairs under high and low temperature environments. The life of lubricating grease for sliding friction pairs is tested. The grease is made to pass through a stable wear stage through a first stage test, and then the service life of the grease is tested and evaluated through a second stage test. The life evaluation of the lubricating grease for sliding friction pairs is fast and accurate, and the grease can be used in both high and low temperature environments, thereby improving the scope of application of the grease life evaluation method.

[0020] 2. The second stage test of the present invention is operated at 1.05-2 times the rated load, and the accelerated wear test is performed without changing the failure mode of the friction pair, thereby reducing the bench operation time, improving the bench operation efficiency, and improving the accuracy of the second stage test of the grease.

[0021] 3. The sliding friction pair test bench in the present invention is placed in an environmental chamber, which can provide an environmental temperature of -60°C to 100°C. The life test and evaluation of the grease can be carried out at low or high temperatures, and the accuracy of the evaluation can be guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 The present invention is a flow chart of a method for evaluating the life of grease for sliding friction pairs under high and low temperature environments.

[0024] Figure 2 The friction life curve diagram is a method for evaluating the life of grease for sliding friction pairs under high and low temperature environments in the present invention.

[0025] Figure 3 The present invention is a schematic structural diagram of a sliding friction pair test bench for a method for evaluating the life of lubricating grease for sliding friction pairs under high and low temperature environments.

[0026] Figure 4 This is the wear condition of the friction pair of prototype 1 of a method for evaluating the life of grease for sliding friction pairs under high and low temperature environments in the present invention.

[0027] Figure 5 This is the wear condition of the friction pair of Prototype 2 of a method for evaluating the life of grease for sliding friction pairs under high and low temperature environments in the present invention.

[0028] Figure 6 This is the wear condition of the friction pair in Example 2 of a method for evaluating the life of grease for sliding friction pairs under high and low temperature environments in the present invention.

[0029] In the figure, 1-fixed seat, 2-pin shaft, 21-injection channel, 3-sleeve, 4-sealing ring, 5-thermocouple. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0031] The terms "first", "second", "third", "fourth", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances. For example, without departing from the scope of this document, the first information can also be referred to as the second information, and similarly, the second information can also be referred to as the first information.

[0032] The word "if" as used herein may be interpreted as "when" or "when" or "in response to determining," depending on the context.

[0033] Furthermore, as used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context indicates otherwise.

[0034] It should be further understood that the terms “comprises” and “includes” indicate the existence of features, steps, operations, elements, components, items, types, and / or groups, but do not exclude the existence, occurrence, or addition of one or more other features, steps, operations, elements, components, items, types, and / or groups.

[0035] The terms "or" and "and / or" used herein are interpreted as inclusive, or mean any one or any combination. Thus, "A, B or C" or "A, B and / or C" means "any of the following: A; B; C; A and B; A and C; B and C; A, B and C". An exception to this definition will only occur when a combination of elements, functions, steps or operations are inherently mutually exclusive in some manner.

[0036] Embodiment 1:

[0037] A method for evaluating the life of grease for sliding friction pairs under high and low temperature environments, relying on Figure 3 The sliding friction pair test bench shown below is used for testing:

[0038] A fixed seat 1, a pin 2 and a sleeve 3, both ends of the pin 2 are fixedly connected to the fixed seat 1, the sleeve 3 is sleeved on the pin 2, and the sleeve 3 is connected to an external drive device to complete the relative rotation of the pin 2, forming a set of sliding friction pairs, the rotation angle is not less than 50°, and a positive pressure is provided to apply a load to the sliding friction pair, and the maximum positive pressure is not less than 100MPa, which can be adjusted arbitrarily within the range of 0 to the maximum positive pressure. An injection channel 21 is provided at one end of the pin 2, and the outlet of the injection channel 21 is on the side wall of the pin 2, which is used to add grease between the pin 2 and the sleeve 3. A sealing ring 4 is provided on the outside of the injection channel 21 for sealing the grease. A thermocouple 5 is provided at the other end of the pin 2 for detecting the operating temperature.

[0039] The materials and specifications of the pin 2 and the sleeve 3 can be selected according to the use conditions and actual needs of different hinge points of the construction machinery. When selecting a friction pair, its rated load needs to match the radial load that the sliding friction pair test bench can provide. For example, when the rated load of the friction pair is N, the sliding friction pair test bench should be able to provide a radial load of more than 2N.

[0040] The sliding friction pair test bench is set in an environmental chamber, which can provide a closed space and adjust the temperature to simulate working conditions in different environments.

[0041] like Figure 2 As shown, based on the tribological principles and wear curves, the friction pair will go through three stages: running-in stage, stable wear stage and severe wear stage as the running time increases, and the noise, friction coefficient and temperature change trends will also appear in different wear stages.

[0042] During the running-in stage, since the friction pair surface itself is not completely smooth, the friction coefficient will be large in the early stage of friction, the wear will increase rapidly, and even be accompanied by abnormal noise. Under the premise of a specific friction pair and sufficient lubrication, the role of the grease to be tested is reflected in the formation of a stable and effective oil film and / or adsorption film on the friction surface, isolating the friction surface, thereby achieving the purpose of lubrication, reducing friction and wear, and eliminating the early abnormal noise of the friction pair. According to the wear curve, the wear of the friction pair in the running-in stage usually increases rapidly with the extension of operating time, accompanied by abnormal noise. After the introduction of grease, the friction and wear of the friction pair will usually decrease and the abnormal noise time will be shortened. The disappearance of the abnormal noise indicates that the running-in stage of the friction pair has ended or the stable wear stage has begun. The shorter the running-in stage, the better the first stage test of the grease, that is, the performance of effectively reducing running-in wear.

[0043] After the friction pair enters the stable wear stage, in addition to evaluating the lubricating performance of the grease under the rated load of the friction pair, you can also choose to accelerate the test method under a moderately exceeded rated load to quickly evaluate the anti-wear performance and service life of the grease. With the continuous operation of the friction pair, when the grease cannot form a complete oil film and / or adsorption film on the surface of the friction pair, dry friction and wear will occur in the friction pair, which may be accompanied by abnormal noise. At the same time, its friction coefficient increases rapidly, and the temperature of the friction surface also rises rapidly, which means that the grease has failed. The more times the friction pair operates stably, the longer the service life of the grease.

[0044] like Figure 1 As shown, a method for evaluating the life of a lubricating grease for a sliding friction pair under a high and low temperature environment in this embodiment includes the following steps:

[0045] S1. Preparation before testing: Perform preparation work before testing the life of the grease used in sliding friction pairs.

[0046] S11. Grease injection: Inject grease from the injection channel, rotate to the maximum angle, and inject grease again until grease is seen at the seal. After no-load operation for 0.01h-1h, inject grease again until grease is seen at the seal, so as to achieve sufficient grease filling and sufficient lubrication of the friction pair.

[0047] S12. Set temperature: Set the temperature of the environmental chamber according to the working conditions, so that the temperature of the sliding friction pair test bench is constant at the actual working temperature. After injecting grease, adjust it at the actual working temperature for at least 3 hours to make the sliding friction pair test bench and grease adapt to the current ambient temperature.

[0048] S2. First stage test: The first stage test is performed on the grease on the sliding friction pair test bench: the grease is adjusted at a set temperature and operated under a rated load to obtain the first stage test data, and whether the first stage test is passed is determined based on the first stage test data;

[0049] The first stage test data includes the number of friction pair operation times and abnormal noise operation times, the highest temperature, the friction coefficient and the noise value during operation. The first stage test data also includes the wear state of the friction pair, and the wear state of the friction pair can be tested according to actual needs. During the rotation of the sleeve 3, the number of friction pair operations is recorded by the counting sensor, and the noise value during operation is measured by the decibel meter. When the noise value reaches the abnormal noise decibel, the counting sensor records the number of abnormal noise operations. The highest temperature during operation is detected by the thermocouple 5. The detection temperature can be detected by center punching or quadratic interpolation.

[0050] In the first stage test, the number of operations under rated load does not exceed the maximum set number. The last several operation times within the maximum set number are used as auxiliary judgment times. In this embodiment, the maximum set number is 5000 times, the minimum number of operations is 2000 times, the maximum number is 5000 times, and the 4000th to 5000th times are auxiliary judgment times. If no abnormal sound occurs, no abnormal sound occurs after the abnormal sound occurs, or the continuous abnormal sound exceeds the specified number of times, the first stage test is terminated. No new grease is injected during the test.

[0051] The steps for judging whether the first phase test has been passed based on the first phase test data include:

[0052] If the maximum temperature and friction coefficient do not exceed the critical value, the vehicle is judged to have passed the first stage test, and the fewer times of abnormal noise operation, the higher the evaluation level;

[0053] If the high temperature or friction coefficient exceeds the critical value, or the number of operations exceeds the maximum set number of times and there is still abnormal noise, it is judged that the first stage test has not passed.

[0054] The evaluation results of the first stage test of the grease in this embodiment are shown in the following table:

[0055]

[0056] S3. Second stage test: If the first stage test is passed, the grease is further subjected to a second stage test based on the first stage test: the grease is operated at a load higher than the rated load to obtain the second stage test data, and the life grade of the grease is determined based on the second stage test data.

[0057] The test data of the second stage include the wear state of the friction pair, the number of times the friction pair operates, the maximum temperature, the friction coefficient and the value of abnormal noise during operation. During the rotation of the sleeve 3, the number of times the friction pair operates is recorded by a counter, and the noise value during operation is measured by a decibel meter. When the noise value reaches the abnormal noise decibel, the counter records the number of abnormal noise operations. The highest temperature during operation is detected by a thermocouple 5. The detection temperature can be detected by center punching or quadratic interpolation. No new grease is injected during the test.

[0058] In this embodiment, operating at a load higher than the rated load means operating at 1.1 times the rated load. If the abnormal noise value, the maximum temperature or the friction coefficient exceeds the critical value, the second stage test is terminated.

[0059] In judging the life grade of grease based on the test data of the second phase, when the abnormal noise value, maximum temperature and friction coefficient do not exceed the critical value, the more times the operation is performed, the higher the evaluation grade.

[0060] The evaluation results of the second stage test of the grease in this embodiment are shown in the following table:

[0061]

[0062] Embodiment 2:

[0063] The sliding friction pair in this embodiment uses a 40Cr pin shaft 2 and a powder metallurgy sleeve 3, and the grease to be tested is molybdenum disulfide grease.

[0064] The actual service life of the grease in this embodiment is tested under real conditions. The grease is used in machinery in a sand field and a quarry in Guangxi to verify the service life of the grease.

[0065] Under normal greasing conditions, prototype 1 has no abnormal sound feedback after working continuously for 1500 hours in the sand field, and the average wear of pin 2 is 0.06mm, and the average wear of bushing is 0.08mm. Figure 4 shown.

[0066] Under normal greasing conditions, prototype 2 worked continuously for 1500 hours in the quarry without abnormal noise feedback, and the average wear of pin 2 was 0.02mm, and the average wear of bushing was 0.07mm. Figure 5 shown.

[0067] Prototype 1 and Prototype 2 operate 100 times per hour, and the total operation is more than 120,000 times within 1500 hours of continuous operation.

[0068] Using the life evaluation method of the grease disclosed in the present invention,

[0069] The first stage of testing of the grease on the sliding friction pair test bench: the grease is adjusted at the set temperature and operated under the rated load. The friction pair composed of the pin 2 and the sleeve 3 has no abnormal sound after more than 3,000 times. The maximum operating temperature is 60°C and the maximum friction coefficient is 0.12. The first stage test is evaluated as excellent, and further second stage testing can be carried out.

[0070] For the second stage test, the test was conducted at 1.1 times the rated load based on the first stage test. No grease was added during the operation. The second stage test data was obtained. After the operation times exceeded 120,000 times, no abnormal noise occurred. The maximum temperature was 65°C and the maximum friction coefficient was 0.12. The test was completed. According to the evaluation method of this embodiment, the life of the grease was C-grade. At this time, the average wear of the pin 2 was 0.057mm and the average wear of the bushing was 0.235mm. The wear of the friction pair is shown in the figure below. Figure 6 shown.

[0071] In summary, the preferred grease with a life evaluation grade of C in this patent can achieve no abnormal noise after working for 1500 hours under the actual working conditions of the whole machine, and the maximum wear of the friction pair will not exceed the wear after running 120,000 times under the evaluation method of the grease life disclosed in this disclosure. It can be verified that the evaluation method of the grease life disclosed in this disclosure evaluates the grease in the same way as the service life under the actual working environment, and the evaluation is accurate.

[0072] The test items are shown in the following table:

[0073]

[0074] The test results are shown in the following table:

[0075]

[0076]

[0077] Embodiment 3:

[0078] The friction pair in this embodiment is a pin 2 and a sleeve 3, which are made of 40Cr pins and 8-shaped steel sleeves. An axial blind hole is machined at the center of the other end face of the oiling hole of the pin 2. The end of the hole is about 50 mm away from the end of the oiling hole of the pin shaft 2, and the hole is used as the temperature measuring point.

[0079] The temperature of the environmental chamber was set to a constant temperature of 25°C, and the adjustment time of the bench was 3 hours before the test.

[0080] The test shall be terminated when the temperature exceeds 70°C, the friction coefficient is greater than 0.3, or the abnormal noise exceeds 81dB.

[0081] Six types of grease were tested, each type of grease corresponded to a new friction pair.

[0082] The test items are shown in the following table:

[0083]

[0084]

[0085] The test results are shown in the following table:

[0086]

[0087]

[0088]

[0089] Embodiment 4:

[0090] The friction pair in this embodiment is a pin 2 and a sleeve 3, which are made of 40Cr pins and 8-shaped steel sleeves. An axial blind hole is machined at the center of the other end face of the oiling hole of the pin 2. The end of the hole is about 50 mm away from the end of the oiling hole of the pin shaft 2, and the hole is used as the temperature measuring point.

[0091] This embodiment is tested in a high temperature environment. The temperature of the environmental chamber is set to a constant temperature of 50°C. The adjustment time of the bench is 3 hours before the test.

[0092] The test shall be terminated when the temperature exceeds 70°C, the friction coefficient is greater than 0.3, or the abnormal noise exceeds 81dB.

[0093] One grease was tested.

[0094] The test items are shown in the following table:

[0095]

[0096] The test results are shown in the following table:

[0097]

[0098]

[0099] Embodiment 5:

[0100] The pin shaft 2 and the sleeve 3 in this embodiment are made of 40Cr pin shaft 2 and powder metallurgy sleeve 3. An axial blind hole is machined at the center of the other end face of the oil filling hole of the pin shaft 2. The end of the hole is about 50 mm away from the end of the oiling hole of the pin shaft 2, and the hole is used as the temperature measuring point.

[0101] This embodiment is tested in a low temperature environment. The temperature of the environmental chamber is set to a constant temperature of -20°C. The adjustment time of the bench is 3 hours before the test.

[0102] The test shall be terminated when the temperature exceeds 70°C, the friction coefficient is greater than 0.3, or the abnormal noise exceeds 81dB.

[0103] One grease was tested.

[0104] The test items are shown in the following table:

[0105]

[0106] The test results are shown in the following table:

[0107]

[0108] The grease life evaluation method for sliding friction pairs in this embodiment can be used to evaluate the life of different greases. Through the continuous first-stage test and second-stage test, the life of the grease can be accurately evaluated, and it can be used in both high-temperature and low-temperature environments, thereby improving the scope of application of the grease life evaluation method.

[0109] It should be understood that, although the various steps in the flowcharts in the above-described embodiments are sequentially displayed according to the indications of the arrows, these steps are not necessarily executed sequentially in the order indicated by the arrows. Unless there is a clear description in this article, the execution of these steps is not strictly limited in order, and they can be executed in other orders. Moreover, at least a portion of the steps in the figure may include a plurality of sub-steps or a plurality of stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and their execution order is not necessarily to be carried out sequentially, but can be executed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the above embodiments can still be modified, or some or all of the technical features can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for evaluating the life of grease for sliding friction pairs under high and low temperature environments, characterized in that: The following steps are involved: Carry out the first stage test on the grease on the sliding friction pair test bench: adjust the grease at the set temperature, operate it under the rated load, obtain the first stage test data, and judge whether it passes the first stage test according to the first stage test data; If the first stage test is passed, the grease will be further subjected to a second stage test based on the first stage test: operating at a load higher than the rated load to obtain second stage test data, and the life grade of the grease will be determined based on the second stage test data.

2. The method for evaluating the life of grease for sliding friction pairs under high and low temperature environments according to claim 1, characterized in that: The first phase test data includes the number of friction pair operation times and abnormal noise operation times, maximum temperature, friction coefficient and noise value occurring during operation.

3. The method for evaluating the life of grease for sliding friction pairs under high and low temperature environments according to claim 2, characterized in that: In the first stage test, the number of operations under rated load does not exceed the maximum set number.

4. The method for evaluating the life of grease for sliding friction pairs under high and low temperature environments according to claim 3, characterized in that: In the first stage test, if no abnormal noise occurs, or no abnormal noise occurs again after an abnormal noise occurs, or the number of consecutive abnormal noises exceeds a specified number, the first stage test is terminated.

5. The method for evaluating the life of grease for sliding friction pairs under high and low temperature environments according to claim 4, characterized in that: The step of judging whether the first stage test is passed according to the first stage test data comprises: If the maximum temperature and friction coefficient do not exceed the critical value, the vehicle is judged to have passed the first stage test, and the fewer times of abnormal noise operation, the higher the evaluation level; If the maximum temperature or friction coefficient exceeds the critical value, or the number of operations exceeds the maximum set number of times and there is still abnormal noise, it is judged that the first stage test has not passed.

6. The method for evaluating the life of grease for sliding friction pairs under high and low temperature environments according to claim 1, characterized in that: The second phase test data includes the wear status of the friction pair, the number of times the friction pair operates, the maximum temperature, the friction coefficient, and the value of abnormal noise occurring during operation.

7. The method for evaluating the life of grease for sliding friction pairs under high and low temperature environments according to claim 6, characterized in that: The operation at a load higher than the rated load refers to operation at 1.05-2 times the rated load.

8. The method for evaluating the life of grease for sliding friction pairs under high and low temperature environments according to claim 7, characterized in that: In the second stage test, if the abnormal noise value, the maximum temperature or the friction coefficient exceeds the critical value, the second stage test is terminated.

9. The method for evaluating the life of grease for sliding friction pairs under high and low temperature environments according to claim 8, characterized in that: In determining the life grade of the grease based on the second-stage test data, when the abnormal noise value, the maximum temperature and the friction coefficient do not exceed the critical value, the more times the operation is performed, the higher the evaluation grade.

10. The method for evaluating the life of grease for sliding friction pairs under high and low temperature environments according to claim 1, characterized in that: The sliding friction pair test bench is placed in an environmental chamber, and the environmental chamber is used to adjust the environmental temperature of the friction pair test bench when testing the grease.

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