A hydraulically loaded single ball head rolling contact fatigue testing machine and method thereof

Abstract

The present invention discloses a hydraulically loaded single ball head rolling contact fatigue testing machine and method thereof, and belongs to the field of material rolling contact fatigue performance testing. The device mainly includes a motor, a spindle module, a loading module, a lubrication module and a hydraulic cylinder module; the bottom of the one-way thrust bearing of the spindle module is connected to the upper end surface of the sample in a fit, and is used to support the sample; the first angular contact bearing and the second angular contact bearing are used to prevent the spindle from shaking; the loading module includes a movable crossbeam and a ball head for rolling contact with the lower end surface of the sample, and the movable crossbeam is connected to a hydraulic cylinder module that can provide vertical lifting force. The present invention applies a loading force to the ball head through a hydraulic cylinder, and the constant load output by the hydraulic loading ensures that the ball head does not jump when the sample rotates at high speed. The single ball head loading ensures that the load is unique and that the sample ball and the sample are in a pure rolling state.

Description

Technical Field

[0001] The invention belongs to the field of material rolling contact fatigue performance testing, and in particular relates to a hydraulic loading single ball head type rolling contact fatigue testing machine and a method thereof. Background Art

[0002] Rolling contact fatigue (RCF) failures are common on the surfaces of mechanical parts, such as bearings, gears, axles, wheel rails, and cams. Rolling contact fatigue can cause huge economic losses and reduce the service life of working equipment. There are two types of failure modes of rolling contact fatigue, namely surface-induced and sub-surface-induced. Surface-induced rolling contact fatigue causes micropitting, while sub-surface-induced rolling contact fatigue manifests as material spalling. Once material damage occurs, subsequent damage will accelerate and accumulate, leading to complete failure of the material.

[0003] The rolling contact fatigue testing machine is a device used to test the rolling contact fatigue performance of materials. Generally, the vertical loading method is adopted to load the pressure on the sample, and then the main shaft drives the rolling body to roll back and forth on the sample. The traditional rolling contact fatigue testing machine cannot be well applied to the research and development process of new material technology. The traditional testing machine has the following disadvantages: the test ball and the sample are in a rolling and sliding state, which is not friendly to numerical simulation research; when multiple balls are loaded at the same time, the load of each test ball is inconsistent; the lever loading stability is poor, etc. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects in the prior art and provide a hydraulic loading single ball head rolling contact fatigue testing machine and method thereof. The present invention can ensure that the applied load is constant and the sample ball and the sample are in a pure rolling state.

[0005] The specific technical solutions adopted by the present invention are as follows:

[0006] In a first aspect, the present invention provides a hydraulically loaded single ball head rolling contact fatigue testing machine, which includes a motor, a spindle module, a loading module, a lubrication module and a hydraulic cylinder module;

[0007] The spindle module comprises a spindle, an angular contact bearing sleeve, a first angular contact bearing, a second angular contact bearing, a thrust bearing support, a limit plate and a one-way thrust bearing; the rotating shaft of the motor is connected to the upper end of the spindle through a coupling; the spindle is provided with an angular contact bearing sleeve, a thrust bearing support and a one-way thrust bearing in sequence from top to bottom along the axial direction, and the bottom end is used to fix the sample; the bottom of the one-way thrust bearing is connected to the upper end surface of the sample and is used to support the sample; the shaft plate of the one-way thrust bearing has an interference fit with the spindle, the seat plate has an interference fit with the limit plate, and the limit plate is fixed to the bottom of the thrust bearing support; a second angular contact bearing is provided between the thrust bearing support and the spindle; the inner ring of the second angular contact bearing has an interference fit with the spindle, and the outer ring has an interference fit with the thrust bearing support; A first angular contact bearing is arranged between the angular contact bearing sleeve and the main shaft; the inner ring of the first angular contact bearing is interference fit with the main shaft, and the outer ring is interference fit with the angular contact bearing sleeve; the first angular contact bearing and the second angular contact bearing are used to prevent the main shaft from shaking; the loading module includes a movable crossbeam and a ball head for rolling contact with the lower end surface of the sample, and the ball head is fixed to the movable crossbeam through a ball head retaining frame; the movable crossbeam is connected to a hydraulic cylinder module that can provide vertical lifting force, and the vertical pressure between the ball head and the sample can be changed through the hydraulic cylinder module; the lubrication module includes an oil injection pipe and a plurality of baffles; the oil inlet end of the oil injection pipe is externally connected to a thin oil lubrication pump station, and the oil outlet end rushes to the contact point between the ball head and the sample; the baffle surrounds the outside of the ball head and the sample to prevent lubricating oil from splashing.

[0008] Preferably, the motor is a DC electrode, fixedly mounted on the first support plate; the coupling is a diaphragm-type unit keyway coupling.

[0009] Preferably, the spindle module also includes a second support plate located between the angular contact bearing sleeve and the thrust bearing support, and the three are overlapped in sequence; the spindle passes through the second support plate, and the spindle located above the angular contact bearing sleeve is also provided with a dust ring.

[0010] Furthermore, a plurality of linear bearings are symmetrically arranged on the movable crossbeam; each linear bearing is connected to the second support plate via a guide column to limit the vertical movement of the movable crossbeam.

[0011] Preferably, a freely rolling sphere is embedded in the top of the ball head, and rolling contact with the sample is achieved through the sphere.

[0012] Preferably, the hydraulic cylinder module includes a piston rod, an end cover, a piston sleeve and a sealing ring; the piston rod includes a top section, a middle section and a bottom section which are continuous from top to bottom, and the cross-section of the middle section is larger than that of the bottom section; the top section is fixedly connected to the movable crossbeam; the top of the piston sleeve is fixed to the table top through a flange; the middle section is coaxially sleeved inside the piston sleeve, and a sealing ring is provided between the two, so that the piston rod can slide in a sealed manner in the vertical direction under the limitation of the piston sleeve; the bottom of the piston sleeve is slidingly and sealingly connected to the bottom section through the end cover, and a sealing ring is provided between the end cover and the piston rod; an annular closed action area is formed between the piston sleeve, the end cover, the middle section and the bottom section; a long straight hole is axially opened in the bottom section; one end of the long straight hole is connected to the outside world for refueling, and the other end is connected to the action area, and the oil pressure in the action area can provide a vertical force to the piston rod.

[0013] Furthermore, the top of the piston rod is connected to the movable cross beam through a connecting piece fixed to the bottom of the movable cross beam; the connecting piece is a rotating body structure, and has a threaded hole connected to the piston rod inside.

[0014] Preferably, it also includes a control module, which includes an acceleration sensor, an analog-to-digital converter, a single-chip microcomputer and a host computer; the acceleration sensor is installed on the movable crossbeam to detect its vibration signal, and can transmit the signal to the host computer through the analog-to-digital converter and the single-chip microcomputer in turn.

[0015] Preferably, the bottom of the main shaft has an internal threaded hole, and the sample is fixed to the bottom of the main shaft through the cooperation of a bolt and the internal threaded hole.

[0016] In a second aspect, the present invention provides a method for testing the rolling contact fatigue performance of a material using any of the hydraulically loaded single ball head rolling contact fatigue testing machines described in the first aspect, as follows:

[0017] S1: Before testing, fix the specimen to the bottom of the spindle and make the upper end surface of the specimen fit with the bottom seat of the one-way thrust bearing;

[0018] S2: During the test, the thin oil lubrication pump station is turned on to provide lubricating oil to the sample surface through the oil injection pipe; the hydraulic pump station provides constant pressure to the hydraulic cylinder module to output load to the movable crossbeam, so that the movable crossbeam moves upward, and then the load is transferred to the sample surface through the ball head; the motor drives the main shaft to rotate, so that the sample rotates synchronously; the acceleration sensor monitors the change of the vibration signal of the movable crossbeam during the test. When the amplitude of the vibration signal exceeds the set threshold, it means that the sample is damaged or peeled off, and the motor is turned off;

[0019] S3: Replace the sample and repeat steps S1 and S2 multiple times to complete the rolling contact fatigue performance test of the sample material.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The device of the present invention applies loading force to the ball head through the hydraulic cylinder under the action of an external hydraulic station. The constant load output by the hydraulic loading ensures that the ball head does not jump when the sample rotates at high speed. The single ball head loading ensures that the load is unique and that the sample ball and the sample are in a pure rolling state. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the structure of a hydraulically loaded single-ball rolling contact fatigue testing machine.

[0023] Figure 2 for Figure 1 main view.

[0024] Figure 3 for Figure 2 Side view of.

[0025] Figure 4 A schematic diagram of the loading module structure.

[0026] Figure 5 It is a structural schematic diagram of the hydraulic cylinder module.

[0027] Figure 6 This is a schematic diagram of the structure of the spindle module.

[0028] Figure 7 This is a structural diagram of the lubrication module.

[0029] Figure 8 for Figure 2 A partial view of the .

[0030] In the figure: 1-motor, 2-first support plate, 3-coupling, 4-column, 5-upper lubricating oil tank, 6-middle lubricating oil tank, 7-lower lubricating oil tank, 8-movable crossbeam, 9-table frame, 10-piston rod, 11-end cover, 12-flange, 13-table board, 14-limit sleeve, 15-connecting piece, 16-acceleration sensor, 17-linear bearing, 18-guide column, 19-ball head, 20-dust ring, 21-angular contact bearing sleeve cup, 22-first angular contact bearing, 23-spindle, 24-thrust bearing support, 25-limiting plate, 26-one-way thrust bearing, 27-sample, 28-ball head retainer, 29-piston sleeve, 30-sealing ring, 31-second support plate, 32-injection pipe, 33-thin oil lubrication pump station, 34-second angular contact bearing. DETAILED DESCRIPTION

[0031] The present invention is further described and illustrated below in conjunction with the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly without conflicting with each other.

[0032] like Figures 1 to 3 As shown, a hydraulically loaded single-ball rolling contact fatigue testing machine provided by the present invention is specifically a hydraulically loaded single-ball rolling contact fatigue testing machine for conducting pure rolling point (circle) contact rolling contact fatigue experiments under constant loading pressure. The device mainly includes a driving module, a spindle module, a loading module, a lubrication module and a hydraulic cylinder module, wherein the motor in the driving module provides kinetic energy for the sample, and the external hydraulic pump station provides loading force for the hydraulic cylinder module and the loading module, so that the ball head in the loading module applies a load to the sample, ensuring that the applied load is unique and constant, and the sample ball in the ball head and the sample are in a pure rolling state; the lubrication module provides oil spray lubrication for the spindle module and can prevent oil splashing. A control module can also be added as needed, and the acceleration sensor in the control module is used to monitor the rolling contact fatigue failure of the sample. When the amplitude of the monitored vibration signal exceeds the threshold, the experiment ends and the testing machine stops working.

[0033] The structure and connection method of each module will be described in detail below.

[0034] The driving module mainly includes a motor 1 and a coupling 3. The output shaft of the motor 1 is connected to the main shaft 23 of the main shaft module through the coupling 3, and can transmit power to the main shaft 23, thereby driving the sample 27 to rotate. In this embodiment, the driving module also includes a first support plate 2, and the motor 1 is fixedly mounted on the first support plate 2. The motor 1 can be a DC high-speed motor, and the coupling 3 can be a diaphragm-type unit keyway coupling.

[0035] like Figure 6As shown, the spindle module mainly includes a spindle 23, an angular contact bearing sleeve 21, a first angular contact bearing 22, a second angular contact bearing 34, a thrust bearing support 24, a stop plate 25 and a one-way thrust bearing 26. The rotating shaft of the motor 1 is connected to the upper end of the spindle 23 through a coupling 3. The spindle 23 is provided with an angular contact bearing sleeve 21, a thrust bearing support 24 and a one-way thrust bearing 26 in sequence from top to bottom along the axial direction, and the bottom end is used to fix the sample 27. The bottom of the one-way thrust bearing 26 is connected to the upper end surface of the sample 27 and is used to support the sample 27. The shaft piece of the one-way thrust bearing 26 is interference fit with the spindle 23, and the seat piece is interference fit with the stop plate 25, and the stop plate 25 is fixed to the bottom of the thrust bearing support 24. A second angular contact bearing 34 is provided between the thrust bearing support 24 and the spindle 23. The inner ring of the second angular contact bearing 34 is interference fit with the main shaft 23, and the outer ring is interference fit with the thrust bearing support 24. A first angular contact bearing 22 is provided between the angular contact bearing sleeve 21 and the main shaft 23. The inner ring of the first angular contact bearing 22 is interference fit with the main shaft 23, and the outer ring is interference fit with the angular contact bearing sleeve 21. The first angular contact bearing 22 and the second angular contact bearing 34 are used to prevent the main shaft 23 from shaking.

[0036] Specifically, in this embodiment, the main shaft 23 can be divided into 5 continuous shaft sections from bottom to top, and the bottom end of the first shaft section at the bottom has an internal threaded hole, and the sample 27 is installed on the lower end of the main shaft 23 by an M12 internal hexagonal cylindrical head bolt. The one-way thrust bearing 26 can be of model 51205, specifically to support the sample 27 and prevent the sample 27 from sliding upward along the main shaft 23, and its shaft piece is interference fit with the first shaft section of the main shaft 23, and the seat piece is interference fit with the limit piece 25. The limit piece 25 is installed on the thrust bearing support 24 by 4 M6 bolts. The second shaft section of the main shaft 23 is interference fit with the inner ring of the second angular contact bearing 34, and the second angular contact bearing 34 can be of model 207BEP, and the outer ring of the second angular contact bearing 34 is interference fit with the thrust bearing support 24. A second support plate 31 is sleeved on the third shaft section. The fourth shaft section of the main shaft 23 is interference fit with the inner ring of the first angular contact bearing 22. The first angular contact bearing 22 can be of model 207BEP. The outer ring of the first angular contact bearing 22 is interference fit with the angular contact bearing sleeve cup 21. The corners of the upper end surface of the thrust bearing support 24 are respectively provided with internal threaded holes. The second support plate 31 and the angular contact bearing sleeve cup 21 are respectively provided with through holes and countersunk through holes at the same positions. The thrust bearing support 24, the second support plate 31 and the angular contact bearing sleeve cup 21 are installed together by 4 M12 hexagon socket bolts. The thrust bearing support 24, the second support plate 31 and the angular contact bearing sleeve cup 21 are stacked from bottom to top to form a whole. The upper end of the fifth shaft section of the main shaft 23 is separated with a keyway. The dust ring 20 is sleeved in the keyway opened on the fifth shaft section and is used for dust prevention when the device is not working.

[0037] like Figure 4 As shown, the loading module mainly includes a movable crossbeam 8 and a ball head 19. The ball head 19 is fixed to the movable crossbeam 8 through a ball head holder 28, and is used for rolling contact with the lower end surface of the sample 27. In this embodiment, the ball head holder 28 is fixed to the upper end surface of the movable crossbeam 8 by three M10 bolts; the loading module also includes linear bearings 17 and connectors 15, and two linear bearings 17 are symmetrically arranged on both sides of the upper end surface of the movable crossbeam 8, and each linear bearing 17 is connected to the second support plate 31 through a guide column 18, so as to limit the vertical movement of the movable crossbeam 8, so that the movable crossbeam 8 can only move in the vertical direction. Figure 8 As shown, the limiting sleeve 14 is sleeved on the outside of the guide column 18 to limit the vertical movement distance of the movable crossbeam 8. The connecting member 15 is installed on the lower end surface of the movable crossbeam 8. The connecting member 15 is a rotating body structure with a threaded hole inside. The piston rod 10 is connected to the loading module through the connecting member 15. A ball bearing is installed in the ball head 19, and a small ball is embedded on the top. The small ball can roll freely on the ball head 19 under the action of the bearing, thereby achieving rolling contact with the sample 27.

[0038] The movable crossbeam 8 is connected to a hydraulic cylinder module that can provide vertical lifting force, and the vertical pressure between the ball head 19 and the sample 27 can be changed through the hydraulic cylinder module. Figure 5As shown, the hydraulic cylinder module mainly includes a piston rod 10, an end cover 11, a piston sleeve 29 and a sealing ring 30. The piston rod 10 is a stepped shaft structure, including a top section, a middle section and a bottom section that are continuous from top to bottom, and the cross section of the middle section is larger than the cross section of the bottom section. The top section is fixedly connected to the movable crossbeam 8. The top of the piston sleeve 29 is fixed to the table board 13 through a flange 12, and the table board 13 is fixed to the ground through a table frame 9. In actual application, the first support plate 2 and the table board 13 can also be installed at both ends of the four columns 4 through 8 hexagon socket bolts. The middle section is coaxially spaced and sleeved inside the piston sleeve 29, and a sealing ring 30 is provided between the two. The piston rod 10 can slide in a sealed manner in the vertical direction under the limit of the piston sleeve 29. The bottom of the piston sleeve 29 is connected to the bottom section in a sliding and sealing manner through the end cover 11, and the end cover 11 and the bottom section are gap-matched and a sealing ring is provided between the two. Since the cross section of the middle section is larger than that of the bottom section, an annular closed action zone is formed between the piston sleeve 29, the end cover 11, the middle section and the bottom section. The bottom section has a tapered threaded hole, and a long straight hole is provided inside along the axial direction. One end of the long straight hole is connected to the outside world for introducing hydraulic oil, and the other end is connected to the action zone, and the oil pressure in the action zone can provide a vertical force on the piston rod 10. In this embodiment, both ends of the piston sleeve 29 have external threads, the piston cylinder flange 12 is installed on the upper end of the piston sleeve 29 through a threaded connection, and the end cover 11 is installed on the lower end of the piston sleeve 29. The inner side of the upper end of the end cover 11 has an internal thread, and the inner side of the lower end is distributed with two sealing grooves for installing O-rings 30.

[0039] like Figure 7 As shown, the lubrication module includes an oil injection pipe 32 and a plurality of baffles. The oil inlet end of the oil injection pipe 32 is externally connected to a thin oil lubrication pump station 33, and the oil outlet end rushes to the contact point between the ball head 19 and the sample 27. The baffle surrounds the outside of the ball head 19 and the sample 27 to prevent the lubricating oil from splashing. In this embodiment, the plurality of baffles can be divided into three parts, namely, an upper lubricating oil tank 5, a middle lubricating oil tank 6 and a lower lubricating oil tank 7, wherein the upper lubricating oil tank 5 and the middle lubricating oil tank 6 can not only be used to prevent the oil from splashing to the outside, but also can act as a guide plate to slide the intercepted oil into the lower lubricating oil tank 7. The lower lubricating oil tank 7 plays the role of collecting the oil, and its bottom is connected to the thin oil lubrication pump station 33 through a pipeline, so as to save energy and achieve reuse. A small hole is opened on the middle lubricating oil tank 6 for fixing the oil injection pipe 32. In actual use, the oil injection pipe 32 is connected to the electric thin oil lubrication pump station 33 . Under the action of the electric thin oil lubrication pump station 33 , the lubricating oil is sprayed to the test piece 27 and the ball head 19 through the oil injection pipe 32 for lubrication.

[0040] The control module includes an acceleration sensor 16, an analog-to-digital converter, a single-chip microcomputer and a host computer. The acceleration sensor 16 is installed on the movable crossbeam 8 to detect its vibration signal. The detected signal can be transmitted to the host computer through the analog-to-digital converter and the single-chip microcomputer in turn, and processed in the host computer.

[0041] The material rolling contact fatigue performance testing method using the above-mentioned hydraulic loading single ball head rolling contact fatigue testing machine is as follows:

[0042] S1: Before the test, fix the sample 27 to the bottom of the main shaft 23, and make the upper end face of the sample 27 fit with the bottom seat of the one-way thrust bearing 26. Specifically, according to the test requirements, the sample 27 can be processed into a circular shape with a through hole of 13mm in the middle, and installed on the end face of the first shaft section of the main shaft 23 by an M12 hexagon socket bolt.

[0043] S2: During the test, the thin oil lubrication pump station 33 is turned on to provide lubricating oil to the surface of the sample 27 through the oil injection pipe 32. The hydraulic pump station provides constant pressure to the hydraulic cylinder module, outputs load to the movable crossbeam 8, causes the movable crossbeam 8 to move upward, and then transmits the load to the surface of the sample 27 through the ball head 19. The motor 1 drives the main shaft 23 to rotate, so that the sample 27 rotates synchronously.

[0044] At the beginning of the experiment, the control module is turned on, and the changes in the vibration signal of the movable crossbeam 8 during the test are monitored by the acceleration sensor 16, and sent to the computer for processing. When the amplitude of the vibration signal exceeds the set threshold, it means that the sample 27 is damaged or peeled off, and the host computer sends a command to the single-chip microcomputer to control the motor 1 to stop, and settle the experimental weeks and record the experimental results.

[0045] S3: Replace the sample 27 and repeat steps S1 and S2 multiple times to complete the rolling contact fatigue performance test of the sample 27 material.

[0046] The above-described embodiment is only a preferred solution of the present invention, but it is not intended to limit the present invention. A person skilled in the relevant technical field may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims

1. A hydraulically loaded single ball head rolling contact fatigue testing machine, characterized in that: It includes a motor (1), a spindle module, a loading module, a lubrication module and a hydraulic cylinder module; The spindle module comprises a spindle (23), an angular contact bearing sleeve (21), a first angular contact bearing (22), a second angular contact bearing (34), a thrust bearing support (24), a limit plate (25) and a one-way thrust bearing (26); the rotating shaft of the motor (1) is transmission-connected to the upper end of the spindle (23) via a coupling (3); the spindle (23) is sleeved with an angular contact bearing sleeve (21), a thrust bearing support (24) and a one-way thrust bearing (26) in sequence from top to bottom along the axial direction, and the bottom end is used to fix the sample ( 27); the bottom of the one-way thrust bearing (26) is closely connected to the upper end surface of the sample (27) for supporting the sample (27); the shaft of the one-way thrust bearing (26) is interference fit with the main shaft (23), the seat is interference fit with the limit plate (25), and the limit plate (25) is fixed to the bottom of the thrust bearing support (24); a second angular contact bearing (34) is provided between the thrust bearing support (24) and the main shaft (23); the inner ring of the second angular contact bearing (34) is interference fit with the main shaft (23), and the outer ring is interference fit with the thrust bearing support (2 4) interference fit; a first angular contact bearing (22) is provided between the angular contact bearing sleeve (21) and the main shaft (23); the inner ring of the first angular contact bearing (22) is interference fit with the main shaft (23), and the outer ring is interference fit with the angular contact bearing sleeve (21); the first angular contact bearing (22) and the second angular contact bearing (34) are used to prevent the main shaft (23) from shaking; the loading module includes a movable crossbeam (8) and a ball head (19) for rolling contact with the lower end surface of the sample (27), and the ball head (19) is held by a ball head retainer ( 28) is fixed on the movable crossbeam (8); the movable crossbeam (8) is connected to a hydraulic cylinder module that can provide a vertical lifting force, and the vertical pressure between the ball head (19) and the sample (27) can be changed through the hydraulic cylinder module; the lubrication module includes an oil injection pipe (32) and a plurality of baffles; the oil inlet end of the oil injection pipe (32) is externally connected to a thin oil lubrication pump station (33), and the oil outlet end rushes to the contact point between the ball head (19) and the sample (27); the baffle surrounds the outside of the ball head (19) and the sample (27) to prevent the lubricating oil from splashing; A plurality of linear bearings (17) are symmetrically arranged on the movable crossbeam (8); each linear bearing (17) is connected to the second support plate (31) via a guide column (18) to limit the vertical movement of the movable crossbeam (8); A freely rolling sphere is embedded on the top of the ball head (19), and rolling contact with the sample (27) is achieved through the sphere; It also includes a control module, which includes an acceleration sensor (16), an analog-to-digital converter, a single-chip microcomputer and a host computer; the acceleration sensor (16) is installed on the movable crossbeam (8) and is used to detect its vibration signal, and can transmit the signal to the host computer through the analog-to-digital converter and the single-chip microcomputer in sequence.

2. The hydraulic loading single ball head rolling contact fatigue testing machine according to claim 1, characterized in that: The motor (1) is a DC electrode, fixedly mounted on the first support plate (2); the coupling (3) is a diaphragm-type unit keyway coupling.

3. The hydraulic loading single ball head rolling contact fatigue testing machine according to claim 1, characterized in that: The spindle module further comprises a second support plate (31) located between the angular contact bearing sleeve (21) and the thrust bearing support (24), and the three are stacked in sequence; the spindle (23) passes through the second support plate (31), and the spindle (23) located above the angular contact bearing sleeve (21) is also sleeved with a dust ring (20).

4. The hydraulic loading single ball head rolling contact fatigue testing machine according to claim 1, characterized in that: The hydraulic cylinder module comprises a piston rod (10), an end cover (11), a piston sleeve (29) and a sealing ring (30); the piston rod (10) comprises a top section, a middle section and a bottom section which are continuous from top to bottom, and the cross section of the middle section is larger than the cross section of the bottom section; the top section is fixedly connected to the movable crossbeam (8); the top of the piston sleeve (29) is fixed to the table top (13) via a flange (12); the middle section is coaxially spaced and sleeved inside the piston sleeve (29), and a sealing ring (30) is provided between the two, so that the piston rod (10) can be moved in the movable crossbeam (8) at a fixed position. The piston sleeve (29) is limited and slides in a sealed manner in the vertical direction; the bottom of the piston sleeve (29) is slidably and sealedly connected to the bottom section through the end cover (11), and a sealing ring (30) is provided between the end cover (11) and the piston rod (10); an annular closed action area is formed between the piston sleeve (29), the end cover (11), the middle section and the bottom section; a long straight hole is axially provided in the bottom section; one end of the long straight hole is connected to the outside for oiling, and the other end is connected to the action area, and the oil pressure in the action area can provide a vertical force on the piston rod (10).

5. The hydraulic loading single ball head rolling contact fatigue testing machine according to claim 4, characterized in that: The top of the piston rod (10) is connected to the movable cross beam (8) via a connecting piece (15) fixed to the bottom of the movable cross beam (8); the connecting piece (15) is a rotating body structure and has a threaded hole inside that is connected to the piston rod (10).

6. The hydraulic loading single ball head rolling contact fatigue testing machine according to claim 1, characterized in that: The bottom of the main shaft (23) is provided with an internal threaded hole, and the sample (27) is fixed to the bottom of the main shaft (23) by the cooperation of a bolt and the internal threaded hole.

7. A method for testing the rolling contact fatigue performance of materials using the hydraulically loaded single ball head rolling contact fatigue testing machine according to any one of claims 1 to 6, characterized in that: The details are as follows: S1: Before testing, fix the sample (27) to the bottom of the main shaft (23), and make the upper end surface of the sample (27) fit with the bottom seat of the one-way thrust bearing (26); S2: During the test, the thin oil lubrication pump station (33) is turned on to provide lubricating oil to the surface of the sample (27) through the oil injection pipe (32); the hydraulic pump station provides constant pressure to the hydraulic cylinder module to output a load to the movable crossbeam (8), so that the movable crossbeam (8) moves upward, and then the load is transmitted to the surface of the sample (27) through the ball head (19); the motor (1) drives the main shaft (23) to rotate, so that the sample (27) rotates synchronously; the acceleration sensor (16) monitors the change of the vibration signal of the movable crossbeam (8) during the test. When the amplitude of the vibration signal exceeds the set threshold, it indicates that the sample (27) is damaged or peeled off, and the motor (1) is turned off; S3: Replace the sample (27) and repeat steps S1 and S2 multiple times to complete the rolling contact fatigue performance test of the sample (27) material.

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