Test method for fracture of axle box bearing cage of high-speed train

Abstract

The application discloses a kind of high-speed motor train unit axle box bearing cage fracture test methods, comprising: determining the basic parameters of bearing;According to the basic parameters, the test parameters of bearing are calculated, including bearing radial force, bearing axial force and bearing rotating speed;From bearing finished product, bearing sample piece is extracted;Artificial damage is carried out to bearing sample piece, and the bearing sample piece after damage is installed to test equipment;Test equipment is set according to test parameters, and pre-test is carried out;Test equipment after pre-test tests bearing sample piece under test condition, real-time monitoring test rotating speed, ambient temperature, test bearing temperature and test rig support bearing temperature, whether bearing sample piece meets test condition is judged, if it meets, bearing sample piece is qualified, if it does not meet, bearing sample piece is unqualified.The problem that existing test method cannot evaluate the durability of bearing cage after fracture is solved, the performance test system of axle box bearing is improved, and the quality problem of axle box bearing is better controlled before loading and using, to provide guarantee for train safety.

Description

Technical Field

[0001] This invention relates to the field of rail transit technology, and in particular to a test method for the fracture of the bearing cage of axle box in high-speed trains. Background Technology

[0002] Bearings are key components of high-speed trains, and their performance directly affects the operational safety of the trains. Testing and verification have always been a weak point in the development of high-end bearings. In the verification process of high-speed rail axle box bearings, existing testing methods cannot fully verify the bearing's durability after the cage breaks.

[0003] The bearing cage is a crucial component of a bearing system, its primary function being to maintain the bearing's correct position and withstand axial loads. Although a bearing consists of many parts, the cage is often the first component to fail. This is because it bears immense pressure and vibration and is susceptible to various factors, including excessive loads causing it to rupture, and prolonged use leading to material fatigue that renders it unable to withstand the load. Furthermore, welding problems, manufacturing defects, and improper installation or maintenance can also cause the bearing cage to break. Cage fracture can lead to shortened bearing life, damage, or even seizure. Because the cage is located inside the bearing and its early fracture stages are not significantly different from normal operation, it is difficult to detect through routine monitoring, posing a potential safety hazard.

[0004] There is an urgent need to study test and verification methods for axle box bearings in high-speed trains, so as to conduct more comprehensive testing and verification of various bearing performance characteristics. Summary of the Invention

[0005] This invention provides a test method for cage fracture of axle box bearings in high-speed trains, which solves the problem of the lack of test methods for research tests such as cage fracture tests that affect bearing performance.

[0006] To achieve the above objectives, the present invention provides a method for testing the fracture of the axle box bearing cage in a high-speed train, comprising:

[0007] The basic parameters of the bearing are determined based on the actual operating conditions of the installed bearing housing.

[0008] The test parameters of the bearing are calculated based on the basic parameters, including: bearing radial force, bearing axial force, and bearing speed.

[0009] Bearing samples are extracted from finished bearing products;

[0010] Artificial damage is created on the bearing sample, and the damaged bearing sample is then installed onto the testing equipment.

[0011] The test equipment is set up according to the test parameters, and the test equipment is used for preliminary testing;

[0012] The test equipment after the pre-test tests the bearing sample under the test conditions, and monitors the test speed, ambient temperature, test bearing temperature and test bench support bearing temperature in real time;

[0013] Determine whether the bearing sample meets the test conditions. If it does, the bearing sample is determined to be a qualified sample; if it does not, the bearing sample is determined to be a non-qualified sample.

[0014] Furthermore, the artificial damage inflicted on the bearing sample includes:

[0015] A 1mm fracture was created at the large end edge of the cage pocket of the bearing sample.

[0016] Furthermore, the test equipment undergoes preliminary testing, including:

[0017] The test speed of the test equipment is set to 25%, 50%, 75%, and 100% of the running speed, respectively, and one cycle is run. One cycle includes a forward one-way stroke and a reverse one-way stroke. Each one-way stroke consists of starting speed, constant speed, deceleration, and stopping.

[0018] The axial force of the test equipment is set to 25%, 50%, 75%, and 100% of the axial force of the bearing, respectively, and one cycle is run. One cycle includes a forward one-way stroke and a reverse one-way stroke. Each one-way stroke consists of starting speed, constant speed, deceleration, and stopping.

[0019] Furthermore, the pre-tested testing equipment tests the bearing sample under test conditions, including:

[0020] For either axle box, with an ambient temperature of 20℃, the highest temperature of the rolling bearing in the load zone during the first 20 cycles is ≤100℃, and the highest temperature in the axle box observation zone is ≤80℃. From the 21st cycle onwards, the highest temperature of the rolling bearing in the load zone is ≤90℃, and for up to 1% of the cycles, the highest temperature may be between 90℃ and 100℃; the highest temperature in the axle box observation zone is ≤70℃, and for up to 1% of the basic travel distance, the highest temperature may be between 70℃ and 80℃.

[0021] When the highest temperature of the hottest axle box in the two test axle boxes is ≥50℃, the maximum temperature difference between the load zones of the two axle boxes is ≤20℃ starting from the 21st cycle.

[0022] When the highest temperature of the hottest axle box is ≥50℃, starting from the first cycle, the temperature difference between the two axle boxes in the observation area of ​​the axle box is ≤20℃.

[0023] For either of the two axle boxes, starting from the 21st cycle, the maximum temperature difference within the load zone between cycles is ≤20℃.

[0024] Furthermore, the step of extracting bearing samples from finished bearing products includes:

[0025] The sampling rate for bearing samples was 1 / 16.

[0026] Furthermore, after creating artificial damage to the bearing sample, the process further includes:

[0027] The outer diameter, inner diameter, assembly height, and axial clearance of the bearing sample were remeasured.

[0028] This invention discloses a test method for cage fracture of axle box bearings in high-speed trains. Applying this method, the operating conditions after cage fracture can be simulated. Based on the measured temperature and mileage, the remaining mileage after cage fracture can be determined, thus assessing whether the bearing can safely operate until maintenance. This method solves the problem that existing test methods cannot evaluate the durability performance of bearing cages after fracture, improves the test system for axle box bearing performance, and better controls axle box bearing quality issues before installation and use, providing assurance for train safety. The test method of this invention is feasible and effective. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a flowchart of the test method for the fracture of the axle box bearing cage of the high-speed train according to the present invention;

[0031] Figure 2 This is a schematic diagram of the cage pocket of the present invention;

[0032] Figure 3 This is a schematic diagram of the location of artificial damage at the large end of the present invention;

[0033] Figure 4 This is a schematic diagram of the structure of the two shaft boxes of the test equipment of the present invention;

[0034] Figure 5 This is a schematic diagram showing the location of the observation area and load area of ​​the axle box of the present invention. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Figure 1 The flowchart of the high-speed train axle box bearing cage fracture test method of the present invention includes:

[0037] S1. Determine the basic parameters of the bearing based on the actual operating conditions of the installed axle box assembly;

[0038] S2. Calculate the test parameters of the bearing based on the basic parameters, including: bearing radial force, bearing axial force, and bearing speed;

[0039] S3. Extract bearing samples from finished bearing products;

[0040] S4. Inflate the bearing sample with artificial damage and install the damaged bearing sample onto the test equipment;

[0041] S5. Set up the test equipment according to the test parameters, and conduct a pre-test using the test equipment;

[0042] S6. The test equipment after the pre-test tests the bearing sample under the test conditions, and monitors the test speed, ambient temperature, test bearing temperature and test bench support bearing temperature in real time.

[0043] S7. Determine whether the bearing sample meets the test conditions. If it does, the bearing sample is determined to be a qualified sample; if it does not, the bearing sample is determined to be a non-qualified sample.

[0044] Specifically, in this embodiment, the basic parameters of the bearing are determined based on the actual operating conditions of the axle box assembly. These parameters include: axle weight (kg), unsprung weight (kg), total wear wheel diameter (m), maximum vehicle speed (km / h), test cycle (h), total simulated mileage (km), and initial grease weight (g).

[0045] The test parameters of the bearing are calculated based on the basic parameters, including the bearing radial force, bearing axial force, and bearing speed.

[0046] Specifically, in this embodiment, the bearing speed n is calculated using formula (1).

[0047] n=(100×Vn) / (6×π×D) (1)

[0048] Where n is the bearing speed, with an allowable error of ±3%; D is the total wear wheel diameter; and Vn is the maximum test speed corresponding to the maximum test speed.

[0049] In this embodiment, the bearing radial force is calculated using formula (2).

[0050] Fr=1.2 x 1 / 2 xgx(mm o (2)

[0051] Where Fr is the radial force of the bearing, g is the acceleration due to gravity, 1.2 is the safety factor, 1 / 2 is a coefficient specified considering the number of axle boxes, and m o is the unsprung weight, and m is the axle load.

[0052] In this embodiment, the axial force of the bearing is calculated using formula (3).

[0053] F an =1.2 x 1 / 2 x 0.5 x 0.85 x(10 4 +mg / 3) (3)

[0054] Among them, F an The maximum axial force during the test, 1.2 is a safety factor, 1 / 2 is a coefficient specified considering the number of axle boxes, 0.5 is the average lateral force input during operation, 0.85x(10 4 +mg / 3) represents the lateral force between the wheel and rail.

[0055] In this embodiment, two bearing samples were randomly selected from 32 finished axle box bearings of the same designation and production batch that passed inspection. The sampling rate for bearing samples was 1 / 16. This sampling rate can ensure the stability of bearings for a train.

[0056] This embodiment creates artificial damage to the bearing sample, such as... Figure 2 and Figure 3 As shown, the large end of one pocket of the cage is artificially sawn off, creating a 1mm fracture at the edge of the large end of the cage pocket on the bearing sample. The maximum stress concentration range at the cage edge is within 1mm, making the stress concentration test results more realistic. The appearance of the cage fracture location is photographed and recorded. When the cage manufacturing process is consistent, one type of bearing cage can be selected for testing. A certificate of conformity and inspection reports for bearing dimensions, axial clearance, etc., are attached. Before the test, the testing unit re-measures the external dimensions and axial clearance of the test product, and the measurement results are attached to the test report. After artificially damaging the bearing sample, the outer diameter, inner diameter, assembly height, and axial clearance of the bearing sample are re-measured.

[0057] The plan for setting up the test equipment according to the test parameters and conducting a preliminary test on the test equipment is as follows:

[0058] The preliminary test consists of four cycles. Each cycle includes a forward unidirectional stroke and a reverse unidirectional stroke. Each unidirectional stroke consists of starting speed, constant speed, deceleration, and stopping. Completing the four cycles of the preliminary test ensures more thorough lubrication of the test equipment, which is beneficial to improving the accuracy of subsequent tests.

[0059] The speeds for each test cycle are 25%, 50%, 75%, and 100% of the maximum test speed. The corresponding axial forces are 25%, 50%, 75%, and 100% of the maximum axial force, respectively. Radial force should be maintained throughout the test. The distance of each unidirectional stroke in the pre-test process is not set in advance. The stroke can be ended when the temperature change does not exceed 5°C for at least two hours.

[0060] The overall conditions for the cage fracture test are as follows:

[0061] a) The ventilation device provides cooling air. The wind speed measured near the test shaft box is 8m / s to 10m / s. Ventilation and cooling are maintained during the test and not when the test is stopped.

[0062] b) The ambient temperature requirement is 10℃~40℃.

[0063] The following information needs to be recorded in the cage fracture test of this embodiment:

[0064] During the test, the test speed, ambient temperature, test bearing temperature, and test bench support bearing temperature were monitored in real time. Test data were automatically and continuously recorded by the computer, with each parameter value recorded and saved at 1-minute intervals until the test ended. The maximum temperature difference between the two axle boxes under load was calculated using the ambient temperature, test bearing temperature, and test bench support bearing temperature. The temperature difference between the two axle boxes within their observation areas was also calculated. Figure 4 and Figure 5 As shown, this embodiment shows the locations of the observation area and load area of ​​the two axle boxes.

[0065] The scheme for determining whether the bearing sample meets the test conditions in this embodiment is as follows: If it does, the bearing sample is determined to be a qualified sample; if it does not, the bearing sample is determined to be a non-qualified sample.

[0066] The temperature during the test should meet the following requirements:

[0067] For either of the two axle boxes, when the ambient temperature is 20℃, the highest temperature of the rolling bearing in the load zone measured in the first 20 cycles is ≤100℃.

[0068] For either of the two axle boxes, when the ambient temperature is 20°C, the maximum temperature of the rolling bearing in the load zone measured at the start of the 21st cycle is ≤90°C. For at most 1% of the basic travel mileage, the maximum temperature can be between 90°C and 100°C.

[0069] For either of the two axle boxes, when the ambient temperature is 20℃, the highest temperature in the axle box observation area is ≤80℃ in the first 20 cycles;

[0070] For either axle box, when the ambient temperature is 20℃, starting from the 21st cycle, the highest temperature in the axle box observation area is ≤70℃. For at most 1% of the basic running mileage, the highest temperature can be between 70℃ and 80℃.

[0071] When the highest temperature of the hottest axle box among the two test axle boxes is ≥50℃, the 21st cycle begins. At the same time, the maximum temperature difference between the load areas of the two axle boxes is ≤20℃. For at most 2% of the basic mileage, the maximum temperature difference can be between 20℃ and 25℃.

[0072] When the highest temperature of the hottest axle box among the two test axle boxes is ≥50℃, the 21st cycle begins. The maximum temperature difference between the two axle boxes measured simultaneously within the observation area of ​​the axle box is ≤20℃. For at most 2% of the basic mileage, the maximum temperature difference can be between 20℃ and 25℃.

[0073] For either axle box, starting from the 21st cycle, the maximum temperature difference in the load zone between cycles is ≤20℃. For at most 2% of the basic mileage, the maximum temperature difference can be between 20℃ and 25℃.

[0074] If all the above test conditions are met, the bearing sample is a qualified sample.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A test method for the fracture of the axle box bearing cage in a high-speed train, characterized in that, include: The basic parameters of the bearing are determined based on the actual operating conditions of the installed bearing housing. The test parameters of the bearing are calculated based on the basic parameters, including: bearing radial force, bearing axial force, and bearing speed. Bearing samples are extracted from finished bearing products; The artificial damage to the bearing sample is created by setting a 1mm fracture at the large end edge of the cage pocket of the bearing sample; the damaged bearing sample is then installed on the test equipment. The test equipment is set up according to the test parameters, and the test equipment is used for preliminary testing; Following the preliminary test, the test equipment was used to test the bearing sample under the test conditions, specifically as follows: For either of the two axle boxes, with an ambient temperature of 20℃, the highest temperature of the rolling bearing in the load zone during the first 20 cycles is ≤100℃, and the highest temperature in the axle box observation zone is ≤80℃; starting from the 21st cycle, the highest temperature of the rolling bearing in the load zone is ≤90℃, and the highest temperature in the axle box observation zone is ≤70℃. When the highest temperature of the hottest axle box in the two test axle boxes is ≥50℃, the maximum temperature difference between the load zones of the two axle boxes is ≤20℃ starting from the 21st cycle. When the highest temperature of the hottest axle box is ≥50℃, the temperature difference between the two axle boxes within the observation area of ​​the axle box is ≤20℃. For either of the two axle boxes, starting from the 21st cycle, the maximum temperature difference within the load zone between cycles is measured to be ≤20℃; and the test speed, ambient temperature, test bearing temperature, and test bench support bearing temperature are monitored in real time. Determine whether the bearing sample meets the test conditions. If it does, the bearing sample is determined to be a qualified sample; if it does not, the bearing sample is determined to be a non-qualified sample.

2. The method according to claim 1, characterized in that, The test equipment is used for preliminary testing, including: The test speed of the test equipment is set to 25%, 50%, 75%, and 100% of the running speed, respectively, and one cycle is run. One cycle includes a forward one-way stroke and a reverse one-way stroke. Each one-way stroke consists of starting speed, constant speed, deceleration, and stopping. The axial force of the test equipment is set to 25%, 50%, 75%, and 100% of the axial force of the bearing, and the test is run for one cycle.

3. The method according to claim 1, characterized in that, The step of extracting bearing samples from finished bearing products includes: The sampling rate for bearing samples was 1 / 16.

4. The method according to claim 1, characterized in that, After creating artificial damage to the bearing sample, the process further includes: The outer diameter, inner diameter, assembly height, and axial clearance of the bearing sample were remeasured.

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