Ultra-low vibration deep groove ball bearing fatigue life testing machine and testing method

Abstract

The present invention discloses a testing machine and a testing method for fatigue life of ultra-low vibration deep groove ball bearings. The testing machine is composed of a testing frame, a testing platform, an asynchronous motor located below the testing platform, a transmission mechanism, a testing shaft connected to the transmission mechanism, a testing slot, a simulation body, a loading shell, an axial loading hydraulic cylinder and a radial loading hydraulic cylinder; the testing slot, the simulation body, the loading shell and the axial loading hydraulic cylinder are all fixed on the testing platform; the radial loading hydraulic cylinder is located under the testing platform. The testing method is to extend and retract the simulation body as required, then fix it, and then fix the testing slot; according to the actual working condition of the deep groove ball bearing to be tested, slide the loading shell on the testing shaft; and according to the position of the loading shell, slide the radial loading hydraulic cylinder and fix it, start the asynchronous motor, and apply cyclic loads through the radial loading hydraulic cylinder and the axial loading hydraulic cylinder. The present invention has a reasonable design, reduces the occupation of site space, and has high versatility and applicability.

Description

Technical Field

[0001] The present invention relates to the testing of structural components or equipment not included in other categories, and specifically to a testing machine and a testing method for the fatigue life of an ultra-low vibration deep groove ball bearing. Background Art

[0002] Bearings are important supporting parts of mechanical transmission mechanisms, directly affecting the technical level and quality performance of equipment, and are known as the "joints of industry". Deep groove ball bearings are suitable for high-speed or even ultra-high-speed operation. Deep groove ball bearings are vulnerable parts. The performance of deep groove ball bearings directly affects the stability of the mechanical system and is also one of the main failures of mechanical equipment. Therefore, in order to ensure the safe use of deep groove ball bearings, it is necessary to conduct reliability tests on the bearings using deep groove ball bearing testing machines. Ultra-low vibration deep groove ball bearings have higher requirements for bearing detection technology and testing.

[0003] Ma Wei mentioned in the paper "Bearing Testing Technology and Testing Machine" published in "Engineering and Testing" Volume 62, Issue 2, June 2022: The temperature rise of the test bearing is a comprehensive reflection of the bearing quality, and the temperature rise of the bearing needs to be tested when developing new products. For tests that require lubricating oil during use, the oil supply temperature and oil return temperature of the test bearing also need to be measured. For more demanding tests, the temperature of the lubricating oil supply must also be strictly controlled. The current method is to either set up a cooling mechanism (and the cooling mechanism is relatively complicated, increasing the cost of the entire testing machine) or set up a temperature measuring mechanism. Once the temperature requirement is exceeded, the test needs to be stopped, affecting the test efficiency.

[0004] In addition, the current deep groove ball bearing fatigue life test machine occupies a lot of space in the test site, such as the patent with publication number CN204718808U: a test machine for testing the fatigue life of micro-high-speed deep groove ball bearings, including a test machine housing, a test motor, a fixed base, a test bearing seat, an axial loading device and a test spindle, wherein the test spindle is fixed on the test bearing seat, the test bearing seat and the test spindle are both located in the test machine housing, the test machine housing and the test motor are both fixed on the fixed base, and it is also provided with a flexible fixing member, which connects the shaft of the test motor and the test spindle. Its radial loading device, axial loading device and test motor occupy a lot of space in the horizontal, longitudinal and height directions of the test bench, and occupy a large space in the test site, which is unreasonable in design.

[0005] In addition, current bearings often require customized testing machines based on their actual working conditions, resulting in one testing machine for each bearing, high cost, poor versatility and adaptability. For example, the patent with publication number CN104236912A: A special fatigue life testing machine for outer spherical bearings with seats, including a frame, a test head component, a transmission system, a loading system, a signal amplifier, a temperature sensor, a vibration sensor and a computer monitoring system; it is specially used for fatigue life testing of outer spherical bearings with seats with an inner diameter of φ20-60mm. Summary of the invention

[0006] The purpose of the present invention is to overcome the defects existing in the prior art and provide a testing machine and a testing method for the fatigue life of ultra-low vibration deep groove ball bearings. The testing machine is reasonably designed to reduce the space in the lateral, longitudinal and height directions of the test bench and reduce the space occupied by the test site; a testing machine can be used for testing deep groove ball bearings under a variety of different working conditions, thereby reducing the testing cost and improving the versatility and adaptability of the testing machine.

[0007] To achieve the above purpose, the technical solution of the present invention is to design a test machine for fatigue life of ultra-low vibration deep groove ball bearings, which is composed of a test frame, a test platform fixedly connected above the test frame, an asynchronous motor fixed on the test frame and located below the test platform, a transmission mechanism connected to the asynchronous motor, a test shaft connected to the transmission mechanism, a test slot, a simulation body, a loading shell, an axial loading hydraulic cylinder and a radial loading hydraulic cylinder; the test slot, the simulation body, the loading shell through which the test shaft passes, the test slot, the simulation body, and the axial loading hydraulic cylinder are all fixed on the test platform; the radial loading hydraulic cylinder is located under the test platform. A pair of test slots are provided and are located on both sides of the simulation body; the asynchronous motor is arranged at a position close to one end of the test frame, such as close to one end of the length direction of the test frame. Two test shafts are provided and are arranged outside a pair of test bearings (or test slots); the transmission mechanism is a belt transmission mechanism, and the driven pulley of the belt transmission mechanism is fixedly connected to the test shaft close to it (through a key); the two sides of the retractable shaft of the simulation body are respectively connected to a test shaft through a coupling. The asynchronous motor and the radial loading hydraulic cylinder are arranged below the test platform, making full use of the space of the test rack below the test platform, reducing the space in the height direction of the test bench; and reducing the space occupied by the test site.

[0008] A further technical solution is that the radial loading hydraulic cylinder is fixedly connected to the lower surface of the test platform; the test tank and the simulated body are fixedly connected to the upper surface of the test platform. This solution is used for testing one test machine and one bearing (working condition).

[0009] Another technical solution is that the radial loading hydraulic cylinder and the test groove are both slidably connected to the test platform; there are two parallel blind-hole-shaped sliding grooves on the test platform, and both sides of the test groove are provided with downwardly protruding sliders adapted to the sliding grooves; an oblong hole smaller in size than the sliding groove is provided on the bottom wall of the sliding groove, and a fastening bolt is provided corresponding to the oblong hole, and threaded holes adapted to the fastening bolt are provided at both sides of the test groove and on the slider; the oblong hole penetrates through the test platform;

[0010] The simulated body includes a telescopic housing and a telescopic shaft rotatably arranged in the telescopic housing. The length of the simulated body located between the two test bearings is adjustable to better simulate different working conditions (since the length of the body located between a pair of deep groove ball bearings is different under different working conditions, setting the length of the simulated body to be adjustable can better simulate different working conditions), improving the versatility and adaptability of this test machine. Similar structures are also provided on both sides of the simulated body (that is, second sliders protruding downward and adapted to the sliding grooves are also provided on both sides of the simulated body; third fastening bolts are also provided corresponding to the oblong holes, and threaded holes adapted to the third fastening bolts are provided at both sides of the simulated body and on the second slider); the radial loading hydraulic cylinder is slidably connected to the test platform and can be adjusted according to the required loading torque, improving the adaptability of this test machine. The test groove is slidably connected to the test platform and can better cooperate with the telescopic movement of the simulated body to ensure that there is a placement position for the components on the test platform. After adjusting the position, the test groove, the simulated body, etc. can be fixed through the oblong hole and the fastening bolt on the bottom wall of the sliding groove.

[0011] A further technical solution is that the radial loading hydraulic cylinder is fixedly connected to two "U"-shaped connecting plates through a connecting plate. The two "U"-shaped connecting plates are located at the two side edges of the connecting plate. The two ends of the "U"-shaped connecting plate are integrally provided with sliding plates, and the sliding plates form the outward flanges of the "U"-shaped connecting plate. Two parallel second sliding grooves adapted to the sliding plates are provided on the lower bottom surface of the test platform. An oblong hole smaller in size than the sliding groove is provided on the bottom wall of the second sliding groove, and the oblong hole penetrates through the test platform. A second fastening bolt is provided corresponding to the oblong hole, and a threaded hole adapted to the second fastening bolt is provided on the sliding plate;

[0012] A rectangular through-hole is provided on the test platform. The width of the rectangular through-hole is smaller than the distance between the two second sliding grooves but larger than the size of the loading unit connected to the piston rod of the radial loading hydraulic cylinder. The radial loading hydraulic cylinder can be slidably adjusted to conveniently change the torque according to the working conditions of the bearing to be tested to better conform to its actual working conditions, reduce the number of test machines, and avoid the situation where one test machine is required for each type of bearing. It improves the versatility and adaptability of the deep groove ball bearing fatigue life test machine and improves the popularization of this type of test machine. The setting of the size of the rectangular through-hole on the test platform can ensure that the lower ends of the loading plate and the loading shell do not interfere with the movement of the test platform when the radial loading hydraulic cylinder adjusts its position.

[0013] The loading unit comprises a radial load force sensor fixedly connected to the piston rod of the radial loading hydraulic cylinder, a loading plate fixedly connected to the radial load force sensor, the loading plate abuts against the bottom of the loading shell, a bearing is rotatably arranged in the loading shell, and the test shaft is connected to the aforementioned bearing; the loading shell comprises a pair of semi-ring shells that are oppositely arranged and connected to each other and match the aforementioned bearing;

[0014] The piston rod of the axial loading hydraulic cylinder is fixedly connected with an axial load force sensor, and the end of the axial load force sensor away from the piston rod is fixedly connected with an axial loading plate, and the axial loading plate abuts against the side of the loading shell. A temperature sensor can also be set on the outer wall of the test slot; the temperature sensor can be a K-type or J-type thermocouple with a temperature range of -60℃ to 350℃ and an accuracy of ±1℃.

[0015] A further technical solution is that the test slot is connected to a grease supply device, which is composed of a pump, an opening and closing valve and a controller; an annular cavity protruding outward from the aforementioned bearing is fixedly connected to the side end face of the inner ring of the bearing in the loading shell, an annular cover with a width matching the annular cavity is provided on the side end face of the outer ring of the bearing in the loading shell, a cover is fixedly provided on the side of the annular cover, an opening is provided on the annular cover, an air outlet is provided on the cover, and the size of the opening is larger than the size of the air outlet; an air pipe is connected to the air outlet, and the other end of the air pipe is directly opposite to the oil supply pipe; the oil supply pipe is connected to the pump, and an opening and closing valve is provided on the oil supply pipe. Perforations (i.e., openings) are provided on the surface of the annular cover, and the Bernoulli principle is used to inhale external cold air, and then the airflow is appropriately accelerated through the air outlet, and the airflow is blown to the oil supply pipe of the lubricating oil to realize the cooling of the oil supply pipe by the rotation of the bearing in the loading shell during the test, so as to control the temperature of the lubricating oil supply to meet some tests with relatively demanding requirements.

[0016] It is known from the prior art that the centralized grease supply device is composed of a pump, a distribution valve, a pipe and a control device; the centralized grease supply device can also be used here to quickly and accurately supply the oil (referring to the lubricating oil) required for the test bearings in the two test slots. Or only the grease supply device composed of a pump, an opening and closing valve and a controller of this solution can be used to complete the basic oil supply of the deep groove ball bearing to be tested.

[0017] An ultrasonic lubricating oil detector (such as SDT LUBExpert) can be used to detect whether the deep groove ball bearing to be tested in the test machine has excessive or insufficient lubricating oil. According to the situation detected by the ultrasonic lubricating oil detector, the controller controls the on-off valve to open (or close) and the pump to start (or close), so as to realize automatic and accurate oil supply, which will neither cause insufficient lubricating grease nor excessive lubricating oil in the tested deep groove ball bearing.

[0018] The present invention also provides a technical solution, which is a method for testing the fatigue life of an ultra-low vibration deep groove ball bearing, comprising the following test steps performed in sequence:

[0019] S1, according to the simulated working conditions, the telescopic housing and the telescopic shaft are extended and retracted as required, and then the simulated body is fixedly connected to the test platform, and the two test shafts on both sides of the telescopic shaft are connected to the telescopic shaft through a coupling, and a deep groove ball bearing to be tested is installed on each of the two test shafts, and then the test groove is fixedly connected to the test platform; the test shaft near the end of the test platform is connected to the asynchronous motor through a transmission mechanism;

[0020] S2, according to the actual working condition of the deep groove ball bearing to be tested, slide the loading shell on the test shaft to a suitable position to meet the torque loading of the deep groove ball bearing to be tested; and slide the radial loading hydraulic cylinder according to the position of the loading shell so that the radial loading hydraulic cylinder is located directly below the loading shell, and then fix the radial loading hydraulic cylinder on the test platform;

[0021] S3, the asynchronous motor is started, and the waveform, frequency and amplitude of the load are set according to the test requirements to apply cyclic load through the radial loading hydraulic cylinder and the axial loading hydraulic cylinder to simulate the load changes on the bearing under actual working conditions.

[0022] Set the loading waveform (such as sine wave, square wave, etc.), frequency, amplitude and other parameters according to the test requirements. The loading amplitude should be gradually increased from small to large to simulate the load changes on the bearing under actual working conditions. During the test, the strain, displacement and temperature of the bearing should be monitored in real time. When the bearing is fatigued (such as fracture, crack, etc.) or the preset number of tests is reached, stop the test. Record all data during the test, including parameters such as load, displacement and temperature at the time of failure.

[0023] The advantages and beneficial effects of the present invention are: reasonable design, reducing the space in the horizontal, vertical and height directions of the test bench, and reducing the space occupied by the test site; one test machine can be used to test deep groove ball bearings under various working conditions, thereby reducing the test cost and improving the versatility and adaptability of the test machine;

[0024] The asynchronous motor and the radial loading hydraulic cylinder are arranged below the test platform, making full use of the space of the test rack below the test platform, reducing the space in the height direction of the test bench; and reducing the space occupied by the test site.

[0025] The length of the simulated body located between the two test bearings is adjustable to better simulate different working conditions (because the length of the body located between a pair of deep groove ball bearings is different under different working conditions, setting the length of the simulated body to be adjustable can better simulate different working conditions), improving the versatility and adaptability of this test machine.

[0026] The radially loaded hydraulic cylinder is slidably connected to the test platform and can be adjusted according to the required loading torque, improving the adaptability of this testing machine. The test groove is slidably connected to the test platform and can better cooperate with the simulation of the telescoping of the machine body to ensure a placement position for the components on the test platform. After adjusting the position, the test groove, the simulated machine body, etc. can be fixed through the long circular holes and fastening bolts on the bottom wall of the chute.

[0027] The slidable adjustment of the radially loaded hydraulic cylinder can conveniently change the torque according to the working conditions of the bearing to be tested to better conform to its actual working conditions, reducing the number of testing machines and avoiding the situation where one testing machine is required for each type of bearing. It improves the versatility and adaptability of the deep groove ball bearing fatigue life testing machine and enhances the popularization of this type of testing machine.

[0028] The setting of the size of the rectangular through-hole on the test platform can ensure that when the position of the radially loaded hydraulic cylinder is adjusted, the lower ends of the loading plate and the loading shell do not interfere with the movement of the test platform.

[0029] Perforations (i.e., openings) are provided on the outer surface of the annular cover. By using Bernoulli's principle, external cold air is inhaled, and then the air flow is appropriately accelerated through the air outlet. The air flow blows towards the oil supply pipe of the lubricating oil to cool the oil supply pipe by the rotation of the bearing inside the loading shell during testing, so as to control the temperature of the lubricating oil supply to meet some tests with more stringent requirements. Description of the Drawings

[0030] Figure 1 is a schematic diagram of Embodiment 1 of a testing machine for the fatigue life of an ultra-low vibration deep groove ball bearing according to the present invention;

[0031] Figure 2 is Figure 1 the front view of

[0032] Figure 3 is a schematic diagram of Embodiment 2 of the present invention;

[0033] Figure 4 is Figure 3 the top view of

[0034] Figure 5 is Figure 3 the bottom view of

[0035] Figure 6 is Figure 3 a three-dimensional schematic diagram of the radially loaded hydraulic cylinder, the "U"-shaped connecting plate, the connecting plate, and the sliding plate parts in

[0036] Figure 7 is Figure 3 a schematic diagram of another perspective after removing the test frame and the test platform;

[0037] Figure 8 is Figure 3Perspective view from another angle after removing the fat supply device;

[0038] Fig. 9 is Figure 8 Partial enlarged schematic view of the loading shell part in;

[0039] Fig.10 is Figure 3 Stereoscopic partial schematic view of the test slot in;

[0040] Fig.11 is Figure 3 Side view of the test slot in;

[0041] Fig.12 is Figure 3 Enlarged schematic view of part A in;

[0042] Fig.13 Schematic view of the simulated body in Embodiment 3 of the present invention;

[0043] Fig.14 is Fig.13 Schematic view after stretching;

[0044] Fig.15 is Fig.13 Schematic view showing the injection port and only one hose shown;

[0045] Fig.16 is Fig.13 Side view of the space between two adjacent partitions in;

[0046] Fig.17 is Fig.16 Exploded schematic view of all airbags in.

[0047] In the figure: 1. Test rack; 2. Test platform; 3. Asynchronous motor; 4. Transmission mechanism; 5. Test shaft; 6. Test slot; 7. Simulated body; 8. Loading shell; 9. Axial loading hydraulic cylinder; 10. Radial loading hydraulic cylinder; 11. Slide groove; 12. Slide block; 13. Long oval hole; 14. Fastening bolt; 15. "凵"-shaped connecting plate; 16. Connecting plate; 17. Slide plate; 18. Second slide groove; 19. Second long oval hole; 20. Second fastening bolt; 21. Rectangular through hole; 22. Radial load force sensor; 23. Loading plate; 24. Axial loading plate; 25. Annular cavity; 26. Annular cover shell; 27. Sealing cover; 28. Opening; 29. Air outlet; 30. Air pipe; 31. Oil supply pipe; 32. Pump; 33. Opening and closing valve; 34. Flanging; 35. Large sleeve; 36. Small sleeve; 37. Fastening screw; 38. Partition; 39. Airbag; 40. Injection port; 41. Hose. Detailed implementation manners

[0048] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0049] Embodiment 1: Figure 1 , Figure 2 As shown, the present invention is a testing machine for fatigue life of ultra-low vibration deep groove ball bearings, which is composed of a testing frame 1, a testing platform 2 fixedly connected above the testing frame 1, an asynchronous motor 3 fixed to the testing frame 1 and located below the testing platform 2, a transmission mechanism 4 connected to the asynchronous motor 3, a testing shaft 5 connected to the transmission mechanism 4, a testing slot 6, a simulation body 7, a loading shell 8, an axial loading hydraulic cylinder 9 and a radial loading hydraulic cylinder 10; the testing slot 6, the simulation body 7, the loading shell 8 through which the testing shaft 5 passes, the testing slot 6, the simulation body 7, the axial loading hydraulic cylinder 9 are all fixed on the testing platform 2; the radial loading hydraulic cylinder 10 is located below the testing platform 2. The radial loading hydraulic cylinder 10 is fixedly connected to the lower surface of the testing platform 2; the testing slot 6 and the simulation body 7 are both fixedly connected to the upper surface of the testing platform 2.

[0050] The asynchronous motor is started, and the loading waveform, frequency, and amplitude are set according to the test requirements to apply cyclic loads through radial loading hydraulic cylinders and axial loading hydraulic cylinders to simulate the load changes on the bearings under actual working conditions.

[0051] Embodiment 2: The difference from Embodiment 1 is that Figures 3 to 12 As shown (for ease of illustration, Figure 4 The second oblong hole is not shown; Figure 4 , Figure 5The grease supply device is not shown). The radial loading hydraulic cylinder 10 and the test groove 6 are both slidably connected to the test platform 2. There are two parallel blind hole-shaped sliding grooves 11 on the test platform 2. On both sides of the test groove 6, there are downwardly protruding sliders 12 adapted to the sliding grooves 11. On the bottom wall of the sliding groove, there is an oblong hole 13 smaller in size than the sliding groove. A fastening bolt 14 is provided corresponding to the oblong hole 13. Threaded holes adapted to the fastening bolt 14 are provided on both sides of the test groove 6 and on the slider. The oblong hole penetrates through the test platform 2. The simulated machine body 7 includes a telescopic housing (it can adopt the way that a large sleeve is slidably arranged outside a small sleeve. An outward flanging is provided at the edge of the small sleeve to prevent the large sleeve from detaching. An inward flanging matching the aforementioned outward flanging is provided at the edge of the large sleeve. An oblong hole is provided on the large sleeve for ensuring the relative position of the large sleeve and the small sleeve remains unchanged by a fastening screw after adjusting the sliding position of the large sleeve) and a telescopic shaft rotatably arranged in the telescopic housing (the telescopic shaft is a prior art and will not be elaborated; or it can also adopt the way that a large shaft is sleeved outside a small shaft. Of course, in this case, the large shaft is actually a cylinder with a blind hole at one end, and the small shaft is still a solid body. An oblong hole is provided on the large shaft to ensure the relative position of the large shaft and the small shaft remains unchanged by a fastening bolt after telescoping; an inward flanging is provided at the edge of the blind hole of the large shaft, and an outward flanging matching the inward flanging is provided at the edge of the small shaft). The settings of the telescopic housing and the telescopic shaft can ensure that the spacing between a pair of deep groove ball bearings to be tested conforms to the actual working conditions (or can be adjusted according to the actual working conditions to be consistent with the spacing between a pair of deep groove ball bearings under actual working conditions). The radial loading hydraulic cylinder 10 is fixedly connected to two "U"-shaped connecting plates 15 through a connecting plate 16. The two "U"-shaped connecting plates 15 are located at the two side edges of the connecting plate 16. At both ends of the "U"-shaped connecting plate, there is an integrally formed slide plate 17. The slide plate 17 forms the outward flanging of the "U"-shaped connecting plate 15. On the lower bottom surface of the test platform 2, there are two parallel second sliding grooves 18 adapted to the slide plate 17. On the bottom wall of the second sliding groove 18, there is a second oblong hole 19 smaller in size than the sliding groove. The second oblong hole 19 penetrates through the test platform 2. A second fastening bolt 20 is provided corresponding to the second oblong hole. A threaded hole adapted to the second fastening bolt 20 is provided on the slide plate 17. There is a rectangular through hole 21 on the test platform 2. The width of the rectangular through hole 21 is smaller than the spacing between the two second sliding grooves 18 but larger than the size of the loading unit connected to the piston rod of the radial loading hydraulic cylinder 10.The test slot 6 is connected to a grease supply device, which consists of a pump 32, an on-off valve 33 and a controller; an annular cavity 25 protruding outward from the aforementioned bearing is fixedly connected to the side end face of the inner ring of the bearing in the loading shell 8, an annular cover shell 26 with a width matching that of the annular cavity 25 is provided on the side end face of the outer ring of the bearing in the loading shell 8, a sealing cover 27 is fixedly provided on the side of the annular cover shell, an opening 28 is provided on the annular cover shell, an air outlet 29 is provided on the sealing cover 27, and the size of the opening is larger than that of the air outlet 29; a hole for the test shaft to pass through is provided on the sealing cover, and the test shaft and the hole on the sealing cover are rotatably sealed; an air pipe 30 is connected to the air outlet, and the other end of the air pipe 30 is directly opposite to the oil supply pipe 31; the oil supply pipe 31 is connected to the pump 32, and an on-off valve 33 is provided on the oil supply pipe. An ultrasonic lubricating oil detector (such as SDT LUBExpert) is used to detect whether the deep groove ball bearing to be tested in the test machine has excessive or insufficient lubricating oil. According to the situation detected by the ultrasonic lubricating oil detector, the controller controls the on-off valve to open (or close) and the pump to start (or close), so as to realize automatic and accurate oil supply.

[0052] A pair of test slots are provided and located on both sides of the simulation body; the asynchronous motor is arranged at a position close to one end of the test frame, such as close to one end of the length direction of the test frame. Two test shafts are provided and arranged outside a pair of test bearings (or test slots); the transmission mechanism is a belt transmission mechanism, and the driven pulley of the belt transmission mechanism is fixedly connected to the test shaft close to it (through a key); the two sides of the telescopic shaft of the simulation body are respectively connected to a test shaft through a coupling. The loading unit includes a radial load force sensor 22 fixedly connected to the piston rod of the radial loading hydraulic cylinder, a loading plate fixedly connected to the radial load force sensor, the loading plate 23 abuts against the bottom of the loading shell 8, a bearing is rotatably arranged in the loading shell, and the test shaft is connected to the aforementioned bearing; the loading shell includes a pair of semi-ring shells that are oppositely arranged and connected to each other and match the aforementioned bearing; an axial load force sensor is fixedly connected to the piston rod of the axial loading hydraulic cylinder, and an axial loading plate 24 is fixedly connected to the end of the axial load force sensor away from the aforementioned piston rod, and the axial loading plate abuts against the side of the loading shell.

[0053] The shape of the air outlet 29 on the cover is a cone shape with a size gradually decreasing from the center of the bearing to the cover, so that the airflow can be accelerated to a certain extent. The middle part of the oil supply pipe is a metal pipe; the oil supply pipe and the oil return pipe are set longer, so that the high-temperature oil supply or return oil can be properly cooled due to the long oil pipe. The long part is close to the air outlet, which can reduce the length of the air pipe, ensure a larger airflow, and enhance the cooling effect;

[0054] The test method for fatigue life of ultra-low vibration deep groove ball bearings consists of the following test steps in sequence:

[0055] S1, according to the simulated working conditions, the telescopic housing and the telescopic shaft are extended and retracted as required, and then the simulated body 7 is fixedly connected to the test platform 2, and the two test shafts 5 on both sides of the telescopic shaft are connected to the telescopic shaft through a coupling, and a deep groove ball bearing to be tested is installed on each of the two test shafts 5, and then the test groove 6 is fixedly connected to the test platform 2; the test shaft 5 near the end of the test platform 2 is connected to the asynchronous motor 3 through the transmission mechanism 4;

[0056] S2, according to the actual working condition of the deep groove ball bearing to be tested, slide the loading shell 8 on the test shaft 5 to a suitable position to meet the torque loading of the deep groove ball bearing to be tested; and slide the radial loading hydraulic cylinder 10 according to the position of the loading shell 8 so that the radial loading hydraulic cylinder 10 is located directly below the loading shell 8, and then fix the radial loading hydraulic cylinder 10 on the test platform 2;

[0057] S3, the asynchronous motor 3 is started, and the waveform, frequency and amplitude of the load are set according to the test requirements to apply cyclic loads through the radial loading hydraulic cylinder 10 and the axial loading hydraulic cylinder 9 to simulate the load changes on the bearings under actual working conditions. Perforations (i.e., openings) are set on the surface of the annular cover shell to inhale external cold air using the Bernoulli principle, and then the airflow is appropriately accelerated through the air outlet. The airflow is blown to the oil supply pipe of the lubricating oil to achieve cooling of the oil supply pipe by the rotation of the bearing in the loading shell during the test, so as to control the temperature of the lubricating oil supply to meet some tests with more stringent requirements.

[0058] Embodiment 3: The difference from Embodiment 2 is that Figures 13 to 17 As shown (for ease of illustration, Fig.13The retractable housing adopts a method in which a large sleeve 35 is slidably arranged outside a small sleeve 36. An outer flange 34 is arranged on the edge of the small sleeve to prevent the large sleeve from detaching. An inner flange matching the outer flange is arranged on the edge of the large sleeve. An oblong hole is arranged on the large sleeve to ensure that the relative position of the large sleeve and the small sleeve remains unchanged by tightening screws 37 after adjusting the sliding position of the large sleeve. A plurality of vertically arranged partitions 38 are arranged in the small sleeve 36, and the partitions 38 are arranged equidistantly; the partitions divide the small sleeve 36 into a plurality of spaces, and a plurality of airbags 39 are arranged in each space. A disc-shaped airbag located in the middle and a strip-shaped airbag sleeved (surrounding) outside the middle disc-shaped airbag are arranged in the space between two adjacent partitions. Another strip-shaped airbag of a larger size is sleeved and surrounded outside the strip-shaped airbag, and the arrangement is carried out in sequence until the space between the two adjacent partitions is filled; an injection port 40 is arranged on each airbag 39; in this way, the counterweight of the simulated body can be adjusted according to the actual working conditions, and different airbags can be injected into different spaces. The same liquid or gas as closest to or in line with the actual working conditions (as mentioned in Ma Wei's paper "Bearing Testing Technology and Testing Machine" published in "Engineering and Testing" Volume 62, Issue 2, June 2022: directly adopt the main structure of the axle box and the main shaft when the test bearing is used. This structure is complex, but the test method is closer to the actual working conditions, and is more instructive for the application of bearings. It is mainly used for working condition simulation test machines; this method makes the structure of the test machine very complex; this embodiment adopts this method to adjust the weight of each part of the simulated body according to the main conditions of the axle box and the main shaft when the test bearing is used, so as to conform to the actual working conditions as much as possible). A hose 41 is connected to each injection port 40, and the other end of the hose 41 is located in the middle of the small sleeve after passing through the gap between the large sleeve and the small sleeve (to avoid blocking the end of the hose when the large sleeve slides and unable to inject liquid or gas into the airbag). The side of each airbag is glued to the partition by adhesive so that the airbag can basically maintain its shape (such as a disc or a surrounding strip). This embodiment can be further improved according to actual working conditions, such as setting the disc-shaped airbag or strip-shaped airbag into two independent upper and lower airbags, and the upper and lower airbags are respectively connected to a hose through an injection port, so that different liquids or gases can be injected into the upper and lower independent airbags respectively to make the upper and lower weights in the same space different, which can better meet the actual working conditions. Similarly, the disc-shaped airbag or strip-shaped airbag can also be set into multiple independent small airbags.

[0059] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. Ultra-low vibration deep groove ball bearing fatigue life testing machine, characterized by: It consists of a test rack, a test platform fixedly connected above the test rack, an asynchronous motor fixed on the test rack and located below the test platform, a transmission mechanism connected to the asynchronous motor, a test shaft connected to the transmission mechanism, a test groove, a simulation body, a loading shell, an axial loading hydraulic cylinder and a radial loading hydraulic cylinder; the test shaft passes through the test groove, the simulation body and the loading shell, and the test groove, the simulation body and the axial loading hydraulic cylinder are all fixed on the test platform; the radial loading hydraulic cylinder is located below the test platform; The radial loading hydraulic cylinder, the loading shell and the test groove are all slidably connected to the test platform; the simulation body includes a telescopic shell and a telescopic shaft rotatably arranged in the telescopic shell; The test groove is connected with a grease supply device, and the grease supply device consists of a pump, a switching valve and a controller; on the side end face of the inner ring of the bearing in the loading shell, there is a fixed annular cavity protruding outward from the bearing, and on the side end face of the outer ring of the bearing in the loading shell, there is an annular cover shell with a width matching that of the annular cavity. A cover is fixedly arranged on the side of the annular cover shell, an opening is provided on the annular cover shell, and an air outlet is provided on the cover; a trachea is connected to the air outlet, and the other end of the trachea is directly opposite to the oil supply pipe; the oil supply pipe is connected to the pump, and a switching valve is arranged on the oil supply pipe; the middle part of the oil supply pipe is a metal pipe; The radial loading hydraulic cylinder and the test groove are both slidably connected to the test platform; there are two parallel blind hole-shaped chutes on the test platform, and on both sides of the test groove, there are downward protruding sliders adapted to the chutes; on the bottom wall of the chute, there is an oblong hole smaller in size than the chute, and a fastening bolt is provided corresponding to the oblong hole. Threaded holes adapted to the fastening bolt are provided on both sides of the test groove and on the slider; the oblong hole penetrates through the test platform; The radial loading hydraulic cylinder is fixedly connected to two "U"-shaped connecting plates through a connecting plate. The two "U"-shaped connecting plates are located at both side edges of the connecting plate. At both ends of the "U"-shaped connecting plate, there are integrally formed sliding plates, and the sliding plates form the outward flanges of the "U"-shaped connecting plate. There are two parallel second chutes adapted to the sliding plates on the lower bottom surface of the test platform. On the bottom wall of the second chute, there is a second oblong hole smaller in size than the chute, and the second oblong hole penetrates through the test platform. A second fastening bolt is provided corresponding to the second oblong hole, and threaded holes adapted to the second fastening bolt are provided on the sliding plates; There is a rectangular through hole on the test platform, and the width of the rectangular through hole is smaller than the distance between the two second chutes but larger than the size of the loading unit connected to the piston rod of the radial loading hydraulic cylinder.

2. A method for testing fatigue life of ultra-low vibration deep groove ball bearings, using the testing machine as claimed in claim 1, characterized in that: It consists of the following test steps carried out in sequence: S1, according to the situation of the simulated working condition, extend and contract the telescopic shell and the telescopic shaft as required, then fixedly connect the simulation body to the test platform, connect the two test shafts on both sides of the telescopic shaft to the telescopic shaft through a coupling, install a deep groove ball bearing to be tested on each of the two test shafts, and then fixedly connect the test groove to the test platform; the test shaft near the end of the test platform is connected to the asynchronous motor through a transmission mechanism; S2, according to the actual working condition of the deep groove ball bearing to be tested, slide the loading shell on the test shaft to a suitable position to meet the torque loading of the deep groove ball bearing to be tested; and slide the radial loading hydraulic cylinder according to the position of the loading shell so that the radial loading hydraulic cylinder is located directly below the loading shell, and then fix the radial loading hydraulic cylinder on the test platform; S3, the asynchronous motor is started, and the waveform, frequency and amplitude of the load are set according to the test requirements to apply cyclic load through the radial loading hydraulic cylinder and the axial loading hydraulic cylinder to simulate the load changes on the bearing under actual working conditions.

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