CN112345242A

CN112345242A - Ultra-low temperature rolling bearing service life testing device and testing method

Info

Publication number: CN112345242A
Application number: CN202011153469.0A
Authority: CN
Inventors: 杨朝晖; 李崇赫; 杨宏章; 南凯刚
Original assignee: Xi'an Guze Electromechanical Equipment Co ltd; Northwestern Polytechnical University; Shenzhen Institute of Northwestern Polytechnical University
Current assignee: Xi'an Guze Electromechanical Equipment Co ltd; Northwestern Polytechnical University; Shenzhen Institute of Northwestern Polytechnical University
Priority date: 2020-10-26
Filing date: 2020-10-26
Publication date: 2021-02-09
Anticipated expiration: 2040-10-26
Also published as: CN112345242B

Abstract

The ultra-low temperature rolling bearing life test device and the test method adopt a high-speed heavy-duty mechanical main shaft lubricated by oil gas to drag a test bearing to rotate, the test bearing is positioned in a low-temperature cavity under an ultra-low temperature environment, and a supporting bearing is positioned in a normal-temperature oil gas lubrication cavity. Meanwhile, the support bearing has long service life, does not need to be frequently disassembled and replaced, greatly reduces the test cost and improves the test efficiency.

Description

Ultra-low temperature rolling bearing service life testing device and testing method

Technical Field

The invention belongs to the field of life test of rolling bearings, and particularly relates to a life test method of an ultralow-temperature rolling bearing.

Background

Along with the rapid increase of the requirements of human beings on heavy carrier rockets, the requirements of the rotating speed and the bearing of ultra-low temperature rolling bearings applied to rocket engines are higher and higher, and the service life and the reliability index are more rigorous. Furthermore, reusable rockets place higher demands on the life of this type of bearing. In view of the importance of the service life of the ultralow-temperature bearing on the performance of the rocket engine and the new requirements of the repeatable rocket engine on the service life of the bearing, research on a service life testing device and a testing method of the ultralow-temperature rolling bearing capable of operating for a long time is urgently needed.

The invention with the publication number of CN201910232099.0 discloses a testing device and a testing method for fatigue life of an ultralow-temperature high DN value bearing. The device comprises a device shell, the device shell is connected with an axial flexible loading device and a radial flexible loading device, the axial flexible loading device and the radial flexible loading device are respectively connected with a test rotor, the test rotor comprises a main shaft, a tested bearing, a supporting bearing, a loading bearing and a shaft sleeve are mounted on the main shaft, the main shaft is connected with an end cover through a leather cup sealing element, three medium inlet pipelines are arranged below the shell, and an opening is formed above the shell. After the test device is assembled, a radial flexible loading device and an axial flexible loading device are used for applying load to simulate the load borne by a bearing in a turbopump of the liquid rocket engine; cooling medium enters from a medium inlet pipeline and is discharged from an opening above the shell, so that an ultralow temperature environment is simulated; and starting the test device to operate to a test rotating speed, and simulating the working rotating speed of the bearing. In summary, the device can simulate conditions such as temperature, load and rotating speed, but has the following defects: firstly, the tested bearing, the loading process bearing and the supporting process bearing of the device are all in a low-temperature medium (liquid nitrogen), and the service lives of the loading process bearing and the supporting process bearing are low, so that the testing device cannot perform long-time testing and only can perform service life verification tests due to the fact that the device is limited by the loading bearing and the supporting bearing. Secondly, the cooling efficiency of the device is low due to the low-temperature medium entering mode of the device, the consumption of the cooling medium is high, the outer ring of the tested bearing of the device is located in the outer ring of the tested bearing, the low-temperature medium cannot flow through the outer ring of the tested bearing, the cooling effect of the outer ring of the tested bearing is poor, and the actual working temperature of the turbopump bearing of the rocket engine cannot be completely achieved.

Disclosure of Invention

The invention provides a life test device and a life test method for an ultralow-temperature rolling bearing, aiming at overcoming the defects that a test device in the prior art can not carry out long-time test and can only carry out life verification test and has the defects of low cooling efficiency, high consumption of cooling medium and poor cooling effect of an outer ring of a tested bearing.

The invention provides an ultralow-temperature bearing service life testing device which comprises a driving motor, a loading mechanism, a monitoring system and a testing section. The test section comprises a test cavity and a test shafting, wherein the test cavity is divided into a low-temperature cavity and an oil-gas lubrication cavity; the low-temperature cavity is positioned at the upper end of the oil-gas lubrication cavity and is sealed and isolated from the oil-gas lubrication cavity through a combined sealing structure. The test shaft system is positioned in the test cavity, a mechanical main shaft in the test shaft system penetrates through the oil-gas lubrication cavity, the upper end of the mechanical main shaft is positioned in the low-temperature cavity, and the lower end of the mechanical main shaft penetrates through the main shaft rear end cover and is positioned outside the oil-gas lubrication cavity; the driving motor is connected with the mechanical main shaft. And each input port of the monitoring system is respectively communicated with each sensor distributed in the loading mechanism, the test cavity, the test bearing and the support bearing through data lines. The loading mechanism is positioned at the upper end of the low-temperature cavity, and a loading cylinder in the loading mechanism is fixedly connected with a loading rod. The lower end of the loading rod is positioned in the low-temperature cavity and is connected with a third load applying part in the load applying assembly through a loading bearing; the load bearing is located within the third load applying member.

The cavity of the low-temperature cavity consists of a low-temperature cavity shell, a combined sealing structure and a low-temperature cavity sealing end cover, the load applying assembly and the test bearing are both positioned in the cavity of the low-temperature cavity, and the cavity of the low-temperature cavity is divided into an inner cavity and an outer cavity by the load applying assembly and the test bearing, so that a double-layer structure is formed. The test bearing is sleeved at the upper end of the mechanical main shaft and is positioned in the first load applying part of the load applying assembly. The flow guide head is positioned in the load applying assembly and fixed on the upper end surface of the mechanical main shaft, and the lower end surface of the flow guide head is attached to the upper end surface of the mechanical main shaft and the upper end surface of the gland. And a low-temperature cavity sealing end cover is arranged on the upper end surface of the low-temperature cavity shell. The test bearing is positioned in the low-temperature cavity and sleeved on the mechanical main shaft. The low-temperature cavity shell is provided with a low-temperature medium outlet;

the combined sealing structure comprises a separating disc, a sealing disc and a leaf sealing wheel, and the separating disc, the sealing disc and the leaf sealing wheel are all sleeved on the mechanical main shaft, wherein: the separation disc is fixed on the upper end face of the main shaft shell; the inner surface of the separating disc is in clearance fit with the outer surface of the machine spindle, and two annular sealing grooves which are axially arranged are formed between the inner surface of the separating disc and the outer surface of the machine spindle. The sealing disc is fixed on the upper end surface of the separating disc; the inner surface of the sealing disc is in clearance fit with the outer surface of the machine spindle, and an annular sealing groove is formed between the inner surface of the sealing disc and the outer surface of the machine spindle. A sealing ring mounting groove is formed between the surfaces of the sealing disc and the separating disc, which are attached to each other; and a sealing ring mounting groove is also formed between the separating disc and the upper end surface of the main shaft shell. The blade sealing wheel is connected with the mechanical main shaft through a key, so that the blade sealing wheel can rotate along with the mechanical main shaft; the lower end of the leaf seal wheel is positioned in the groove on the upper surface of the seal disc, and the outer circumferential surface of the leaf seal wheel is in clearance fit with the inner circumferential surface of the seal disc; and the annular sealing groove which are axially arranged on the inner surface of the sealing disc groove form a labyrinth seal between the sealing disc and the leaf seal wheel. A spacer is installed between the upper surface of the impeller and the test bearing in the first load applying member, and an inner circumferential surface of the spacer is in interference fit with an outer circumferential surface of the machine spindle.

The load applying assembly includes a first load applying member, a second load applying member, a third load applying member, and a load bearing. Wherein: the third load applying member is positioned at the upper end of the second load applying member and fixedly connected with the second load applying member through a bolt. The first load applying member is located at the lower end of the second load applying member and is fixedly connected with the second load applying member through a bolt. Two load bearings are located within the third load applying member. The lower end of the loading rod is arranged in the loading bearing and extends into a shaft hole at the upper end of the second load applying piece. A loading bush is installed between the surface of the shaft hole of the upper end of the second load applying member and the outer circumferential surface of the loading rod. The outer circumferential surface of the loading bush is in interference fit with the inner surface of the shaft hole at the upper end of the second load applying member, and the inner circumferential surface of the loading bush is in clearance fit with the outer circumferential surface of the loading rod. The test bearing is seated within the first load applying member. During testing, the loading mechanism applies tension to the loading rod; the loading rod transmits force to the third load applying part through the loading bearing, and then transmits the force to the test bearing through the second load applying part and the first load applying part to finish loading.

The oil-gas lubrication cavity comprises a main shaft shell, a temperature regulation water jacket, a main shaft rear end cover, an inner spacer ring, an outer spacer ring and a bearing spacer ring. The mechanical main shaft penetrates through the oil-gas lubrication cavity, and the fixedly connected section of the mechanical main shaft and the driving motor is positioned outside the lower end surface of the oil-gas lubrication cavity. The inner spacer is positioned in the oil-gas lubrication cavity and sleeved on the outer circumferential surface of the mechanical main shaft; the outer spacer is sleeved on the outer circumferential surface of the inner spacer, and a gap of 4mm is formed between the outer circumferential surface of the inner spacer and the inner circumferential surface of the outer spacer, so that an upper section of a lubricating medium flow passage is formed. The temperature adjusting water jacket is positioned in the main shaft shell and sleeved on the outer circumferential surface of the outer space ring, and the outer surface of the temperature adjusting water jacket is in interference fit with the inner surface of the main shaft shell; the temperature adjusting medium passage located on the outer surface of the temperature adjusting water jacket forms a flow passage for the temperature adjusting medium. The inner surface of the temperature adjusting water jacket is in interference fit with the outer surface of the outer space ring, the outer surface of a support bearing sleeved on the mechanical main shaft and the outer surface of the bearing space ring.

The inner circumferential surface of the lower end of the first load applying member has a radially protruding positioning spigot for positioning and load application of the test bearing. The first load applying member has an outer diameter equal to the maximum outer diameter of the second load applying member, and the first load applying member has an inner diameter equal to the outer diameter of the test bearing outer ring.

The lower end of the second load applying member forms a positioning spigot which cooperates with the first load applying member. The second load applying member has an inner diameter larger than the maximum outer diameter of the flow guide head, and a flow passage for the low-temperature medium is formed between the flow guide head and the inner surface of the second load applying member.

And the outer circumferential surface of the lower end of the third load applying member is provided with a flange connected with the second load applying member. The third load applying member has an inner diameter equal to an outer diameter of the loading bearing outer ring.

The sensor comprises a force sensor, a mass flow meter, a displacement sensor, an acceleration sensor, a temperature sensor and a cavity pressure sensor. Wherein: and a force sensor is arranged at the joint of the loading mechanism and the loading rod. And a low-temperature medium mass flowmeter is arranged at the low-temperature medium inlet. The displacement sensor, the acceleration sensor, the temperature sensor and the cavity pressure sensor respectively penetrate through sensor through holes in the low-temperature cavity shell, the first load applying part and the second load applying part and are arranged on the upper end face of the test bearing retainer. Temperature sensors are respectively arranged in the upper supporting bearing and the lower supporting bearing, and the temperature sensors are arranged in the upper supporting bearing and the lower supporting bearing through sensor through holes on the main shaft shell and the temperature adjusting water jacket.

The test shafting comprises a mechanical main shaft, a gland, a test bearing and a support bearing. The gland is sleeved and fixed at the upper end of the mechanical main shaft, and the test bearing is positioned through the gland. The end face of the upper end of the mechanical main shaft is connected with a flow guide head, and a low-temperature medium is guided into the test bearing through the flow guide head. The lower end of the mechanical main shaft in the oil-gas lubricating cavity is supported by two upper supporting bearings and two lower supporting bearings. The mechanical main shaft is connected with a driving motor through a coupler. The test bearing is positioned within the load applying assembly with the outer circumferential surface of the outer race of the test bearing in clearance fit with the inner circumferential surface of the first load applying member of the load applying assembly.

The upper bearing is positioned at the upper end in the oil-gas lubrication cavity, and the lower bearing is positioned at the lower end in the oil-gas lubrication cavity. The upper supporting bearing and the lower supporting bearing are sleeved on the mechanical main shaft, the upper supporting bearing is positioned above the inner spacing ring and the outer spacing ring, and the lower supporting bearing is positioned below the inner spacing ring and the outer spacing ring. A bearing spacing ring is arranged between the two upper supporting bearings, and a bearing spacing ring is also arranged between the two lower supporting bearings. Each bearing spacer ring is divided into an inner ring and an outer ring, the inner diameter of the outer ring is 1.5mm larger than the outer diameter of the inner ring, and a flow channel of a lubricating medium is formed by an annular cavity between the inner surface of the outer ring and the outer surface of the inner ring. Bosses which are attached to the end faces of the matched supporting bearings are respectively arranged at the outer edges of the upper end faces of the outer rings of the bearing spacing rings and the outer edges of the lower end faces of the outer rings of the bearing spacing rings, and concave faces are respectively formed on the upper end faces and the lower end faces of the outer rings of the bearing spacing rings; the concave surfaces form a flow channel for the lubricating medium.

The spindle rear end cover is fixed on the lower end face of the spindle shell, and the spindle shell is fixed with the temperature adjusting water jacket through the spindle rear end cover. A lower section of a lubricating medium flow channel is formed between the inner surface of the rear end cover of the main shaft and the outer surface of the locking nut; the outer diameter of the end, connected with the main shaft shell, of the main shaft rear end cover is the same as the inner diameter of the temperature adjusting water jacket. The inner surface of the central hole of the flange end of the rear end cover of the main shaft is provided with a radial sealing groove. Four lubricating medium outlets are uniformly distributed on the periphery of the central hole of the flange end, and each lubricating medium outlet is communicated with a lubricating medium flow channel in the oil-gas lubricating cavity; the central line of each lubricating medium outlet is parallel to the central line of the rear end cover of the main shaft.

The upper end of the spindle shell is provided with a temperature adjusting medium outlet which is communicated with a flow channel of a temperature adjusting medium formed by the temperature adjusting medium channel; the central line of the temperature adjusting medium outlet is vertical to the outer surface of the temperature adjusting water jacket. A temperature adjusting medium inlet is arranged on the shell at the lower end of the main shaft shell, and the temperature adjusting medium inlet is communicated with a flow channel of a temperature adjusting medium formed by the temperature adjusting medium channel; the central line of the temperature adjusting medium inlet is perpendicular to the outer surface of the temperature adjusting water jacket. Eight lubricating medium inlets with the inner diameter of 8mm are uniformly distributed on the circumference of the shell at the upper end of the main shaft shell, and each lubricating medium inlet is communicated with the inner cavity of the upper supporting bearing positioned at the upper end of the mechanical main shaft, so that the lubricating medium enters the inner cavity of the upper supporting bearing, and further enters the inner cavity of the lower supporting bearing positioned at the lower end of the mechanical main shaft from the upper section of a lubricating medium flow channel positioned in the oil-gas lubricating cavity. And the inner cavity of the lower supporting bearing is communicated with the lower section of the lubricating medium flow passage.

The lubricating medium flow passage consists of an inner cavity of the upper supporting bearing, an inner cavity of the lower supporting bearing, an inner cavity of the bearing spacer ring, an upper section of the lubricating medium flow passage and a lower section of the lubricating medium flow passage. The upper section of the lubricating medium flow channel is positioned between the supporting bearings at the upper end and the lower end of the outer space ring and consists of a circular cavity between the inner surface of the outer space ring and the outer surface of the inner space ring; the distance between the inner surface of the outer spacing ring and the outer surface of the inner spacing ring is 4 mm. The lower section of the lubricating medium flow channel is positioned below the supporting bearing at the lower end of the outer space ring and is formed by an annular cavity between the outer surface of a locking nut below the lower supporting bearing and the inner surface of a sleeve of the rear end cover of the main shaft; the minimum distance between the outer surface of the locking nut and the inner surface of the sleeve is 12 mm. The locking nut is sleeved on the mechanical main shaft.

The outer space ring is a hollow revolving body, the inner diameter of the outer space ring is 4mm larger than the outer diameter of the inner space ring, the outer diameter of the outer space ring is the same as the inner diameter of the temperature adjusting water jacket, and the outer space ring and the temperature adjusting water jacket are in interference fit. The upper end surface of the outer space ring is attached to the lower end surface of the upper supporting bearing; the lower end face of the outer space ring is attached to the upper end face of the lower supporting bearing. The wall thickness of the outer spacer ring is 20 mm.

The inner spacer is also a hollow revolving body, the inner diameter of the inner spacer is the same as the outer diameter of the mechanical main shaft, and the inner spacer and the mechanical main shaft are in interference fit. The upper end surface of the inner spacer is attached to the lower end surface of the upper supporting bearing; the lower end face of the inner spacer is attached to the upper end face of the lower support bearing. The wall thickness of the inner spacer ring is 6 mm.

The circle center of the separating disc is in clearance fit with the mechanical main shaft. The inner circumferential surface of the separating disc is provided with a radial groove, a sealing ring is arranged in the groove and is fastened by a sealing ring gland; the sealing ring gland is fixed on the upper surface of the separating disc; there is also a seal groove on the lower surface of the separation disc. Eight grooves are uniformly distributed on the lower surface of the sealing disc, and the grooves are communicated with the lubricating medium inlet and the inner cavity of the upper bearing, so that the lubricating medium can pass through the grooves conveniently.

The sealing disc is also hollow disc-shaped. The upper surface of the sealing disc is a stepped surface and is provided with a groove for placing the leaf sealing wheel. The outer edge of the lower surface of the sealing disc is provided with a positioning boss which axially protrudes, and the inner diameter of the positioning boss is the same as the outer diameter of the separation disc; the lower surface of the sealing disc is provided with a sealing groove for mounting a sealing ring. The inner surface of the sealing disc is in clearance fit with the outer surface of the machine spindle. The inner circumferential surface of the sealing disc is provided with a radial groove for installing a sealing ring; the upper surface of the sealing disc is fixed with a sealing ring gland.

The loading rod is a hollow rod with one closed end. The inner hole of the loading rod is a flow channel of a low-temperature medium, and a low-temperature medium inlet is arranged on the loading rod. The center of the lower end opening of the loading rod corresponds to the center of a flow guide head fixed on the upper end face of the mechanical main shaft. A loading force transmission boss which is radially protruded is arranged on the outer circumferential surface close to the lower end of the loading rod; the upper surface of the loading force transmission boss is attached to the lower surface of the loading bearing; the outer diameter of the loading force transmission boss is the same as that of the loading bearing inner ring. The loading rod is provided with a low-temperature medium inlet.

The outer circumferential surface of the upper end of the flow guide head is a conical section; the taper of the conical section is 102 degrees. The center of the lower surface of the conical section is provided with an axial equal-diameter section, and the diameter of the equal-diameter section is the same as the outer diameter of the gland. The center of the lower end surface of the flow guide head is provided with a connecting rod connected with the mechanical main shaft.

The inner diameter of the temperature adjusting water jacket is the same as the outer diameter of the outer space ring, and the temperature adjusting water jacket and the outer space ring are in interference fit; the outer diameter of the temperature adjusting water jacket is the same as that of the main shaft shell, and the temperature adjusting water jacket and the main shaft shell are in interference fit. The outer circumferential surface of the temperature adjusting water jacket is provided with a spiral temperature adjusting medium channel. The temperature-adjusting medium passage was rectangular in cross section, 18mm in width, 5mm in depth, and 5 ° in helix angle.

The specific process of carrying out the loading test by utilizing the ultralow-temperature bearing service life test device provided by the invention is as follows:

step one, determining low-temperature medium flow and lubricating medium flow parameters of the test bearing according to the requirements of the rotating speed and the load provided by the test outline; the set rotation speed of the test bearing was 18000rpm, and the load was 2000 kgf; the flow rate of the low-temperature medium is set to be 10kg/s, and the flow rate of the lubricating medium is set to be 0.03 ml/min.

And step two, assembling the test bearing. And mounting the test bearing on the mechanical main shaft and fixing the test bearing through a gland. And installing the flow guide head on the upper end surface of the mechanical main shaft.

And step three, starting a low-temperature medium source, and introducing a low-temperature medium with the flow rate of 1kg/s into the low-temperature cavity through the hollow loading rod so as to pre-cool the low-temperature cavity. And when the temperature of the low-temperature cavity reaches-196 ℃, closing the low-temperature medium source and ending precooling. The low-temperature medium is liquid nitrogen.

Adjusting parameters of a loading mechanism according to the rotating speed and the load provided by the test outline, and applying the load to the test bearing through the loading mechanism; the applied load simulates the load to which the test bearing is subjected under actual conditions.

And step five, starting a low-temperature medium source, adjusting the flow of the low-temperature medium to 10kg/s, and simulating a low-temperature environment at the temperature of-196 ℃. Meanwhile, introducing a lubricating medium into the oil-gas lubricating cavity and keeping the oil-gas lubricating cavity until the test is finished, so as to provide lubrication for the mechanical main shaft and the support bearing; the lubricating medium is VG68 lubricating oil.

In order to ensure the oil-gas lubrication effect, when the temperature in the oil-gas lubrication cavity is higher than the optimal working temperature of a lubrication medium, liquid nitrogen is introduced into the mechanical water jacket through the temperature regulation medium inlet to reduce the temperature, so that the temperature in the oil-gas lubrication cavity is kept at 40 ℃; when the temperature of the oil-gas lubrication cavity is lower than the optimal working temperature of the lubrication medium, water is introduced into the mechanical water jacket through the temperature regulation medium inlet to raise the temperature, and the temperature of the oil-gas lubrication cavity is kept constant at 40 ℃.

And step six, starting a driving motor, enabling the rotating speed of the test bearing to reach 18000rpm, driving the mechanical spindle to rotate by the driving motor, further driving the test bearing to rotate, and simulating the working rotating speed of the test bearing until data acquisition is completed.

Monitoring the running state of the test device through a monitoring system and recording test data; the test data comprises test bearing temperature, test bearing displacement, test bearing acceleration, cavity pressure at the test bearing, upper support bearing temperature and lower support bearing temperature.

Step seven, after the required test data is obtained, the driving motor is closed, and the mechanical spindle stops rotating; stopping introducing the low-temperature medium, the lubricating medium and the temperature adjusting medium; closing the loading mechanism; and (5) disassembling the test bearing and finishing the test.

In order to realize long-time test of the ultralow-temperature bearing, the oil-gas lubricated high-speed heavy-load mechanical main shaft is adopted to drag the test bearing to rotate, the test bearing is positioned in the low-temperature cavity in the ultralow-temperature environment, and the supporting bearing is positioned in the oil-gas lubricated cavity at normal temperature. Meanwhile, the support bearing has long service life, does not need to be frequently disassembled and replaced, greatly reduces the test cost and improves the test efficiency.

According to the invention, the low-temperature environment cavity and the spindle oil-gas lubrication cavity are isolated by adopting a combined sealing structure, and the combined sealing structure is combined by three forms of leaf seal wheel sealing, labyrinth sealing and sealing ring sealing, so that the leakage and exchange of a low-temperature medium and a lubricating medium can be effectively prevented, and the interface sealing of an ultralow-temperature high-pressure cavity and a normal-temperature low-pressure cavity is realized; meanwhile, the combined sealing structure has the advantages of compact structure and space saving.

The temperature regulating water jacket structure is arranged in the oil-gas lubricating cavity, so that the temperature of the oil-gas lubricating cavity is kept at the optimal working temperature of a lubricating medium, the oil-gas lubricating effect is ensured, and the service life of a supporting bearing is ensured.

In the invention, the low-temperature cavity is of a double-layer structure, as shown in fig. 28, a low-temperature medium enters the cavity in the low-temperature cavity through the hollow loading rod, then is directly guided to the test bearing through the flow guide head structure, then flows into the cavity outside the low-temperature cavity and completely immerses the test bearing, and finally is discharged from the low-temperature medium outlet. As shown in fig. 29, the test bearing can be completely immersed in the low-temperature medium due to the low-temperature medium entering mode and the low-temperature cavity double-layer structure, so that the cooling effect of the test bearing is improved, the consumption of the low-temperature medium is reduced, and the test cost is saved.

Drawings

FIG. 1 is a cross-sectional view of a test device;

FIG. 2 is a cross-sectional view of a test section;

FIG. 3 is a front view of the cryochamber enclosure;

FIG. 4 is a top view of the cryochamber housing;

FIG. 5 is a partial cross-sectional view of a cryogenic chamber housing;

FIG. 6 is a schematic structural view of a load applying assembly;

FIG. 7 is a cross-sectional view of the load applying assembly;

FIG. 8 is a cross-sectional view of the load lever;

FIG. 9 is a schematic view of the structure of the loading bushing;

FIG. 10 is an enlarged view of the portion of the oil and gas lubrication cavity at A in FIG. 2;

FIG. 11 is a schematic structural view of the rear end cap of the spindle;

FIG. 12 is a cross-sectional view of the rear end cap of the spindle;

FIG. 13 is a schematic view of a bearing spacer ring;

FIG. 14 is a cross-sectional view of a bearing spacer ring;

FIG. 15 is a schematic structural view of a temperature adjusting water jacket;

FIG. 16 is a schematic structural view of a composite seal structure;

FIG. 17 is a cross-sectional view of a composite seal structure;

FIG. 18 is a view of the combined seal configuration at B in FIG. 10;

FIG. 19 is a schematic view of the leaf seal wheel;

FIG. 20 is a cross-sectional view of a leaf seal wheel;

FIG. 21 is a schematic view of the seal disk configuration;

FIG. 22 is a cross-sectional view of the seal disk;

FIG. 23 is a schematic view of the structure of a separation disc;

FIG. 24 is a front view of the lower surface of the separation disc;

FIG. 25 is a cross-sectional view of a separation disc;

FIG. 26 is a flow path diagram of the cryogenic medium, the lubricating medium and the temperature regulating medium;

FIG. 27 is a cross-sectional view of section A-A of FIG. 26;

FIG. 28 is a simulation of cryogenic chamber flow traces;

FIG. 29 is a simulation of the temperature field of the cryochamber.

Wherein; 1. a drive motor; 2. a loading mechanism; 3. a monitoring system; 4. a combined sealing structure; 5. a separation disc; 6. sealing the disc; 7. a leaf seal wheel; 8. a low temperature chamber housing; 9. a low temperature medium outlet; 10. sealing the end cover by the low-temperature cavity; 11. a spindle housing; 12. a temperature regulating medium inlet; 13. a temperature regulating medium outlet; 14. a lubricating medium inlet; 15. a main shaft rear end cover; 16. a lubricating medium outlet; 17. a temperature adjusting water jacket; 18. a temperature regulating medium passage; 19. a mechanical spindle; 20. testing the bearing; 21. a gland; 22. a load applying assembly; 23. a first load applying member; 24. a second load applying member; 25. a third load applying member; 26. loading a bearing; 27. a loading rod; 28. loading a force transmission boss; 29. a low temperature medium inlet; 30. loading the bushing; 31. an upper support bearing; 32. a lower support bearing; 33. locking the nut; 34. an inner spacer ring; 35. an outer space ring; 36. a bearing spacer ring; 37. a flow guide head; 38. and (7) a gasket.

Detailed Description

The embodiment is a device for ultra-low temperature rolling bearing life test, and comprises a driving motor 1, a loading mechanism 2, a monitoring system 3 and a test section. The test section comprises a test cavity and a test shafting, wherein the test cavity is divided into a low-temperature cavity and an oil-gas lubrication cavity; the low-temperature cavity is positioned at the upper end of the oil-gas lubrication cavity and is sealed and isolated from the oil-gas lubrication cavity through a combined sealing structure 4. The test shaft system is positioned in the test cavity, and the upper end of a mechanical main shaft 19 in the test shaft system is arranged in the low-temperature cavity. The driving motor 1 is positioned at the lower end of the test shaft system and is connected with the mechanical main shaft 19 through a coupler. And each input port of the monitoring system 3 is respectively communicated with each sensor distributed in the loading mechanism, the test cavity, the test bearing 20 and the support bearing through data lines. The loading mechanism 2 is positioned at the upper end of the low-temperature cavity, and a loading cylinder in the loading mechanism is fixedly connected with a loading rod 27. The lower end of the loading rod 27 is positioned in the low-temperature cavity and is connected with a third load applying part 25 in the load applying assembly 22 through a loading bearing 26; the load bearing 26 is located within the third load applying member 25. The test bearing 20 is positioned in the low-temperature cavity, is sleeved at the upper end of the mechanical main shaft 19 and is positioned in a first load applying piece 23 of a load applying assembly 22; the test bearing 20 is fixed by a gland 21.

The low-temperature cavity is a cavity body surrounded by a low-temperature cavity shell 8, a combined sealing structure 4 and a low-temperature cavity sealing end cover 10. The load applying assembly 22 and the test bearing 20 are located in the low-temperature cavity, and the cavity of the low-temperature cavity is divided into an inner cavity and an outer cavity, so that the low-temperature cavity with a double-layer structure is formed.

The low temperature cavity housing 8 is composed of a cone section and a straight cylinder section. The cone section is fixed on the upper end surface of the straight cylinder section. A through hole for mounting the loading rod 27 is formed in the center of the upper end of the cone section; four low-temperature medium outlets 9 are uniformly distributed on the low-temperature cavity shell 8. The inner diameter of the straight cylinder section is larger than the diameter of the combined sealing structure 4.

The loading mechanism 2, the monitoring system 3 and the driving motor 1 are all in the prior art.

In this embodiment, a plurality of sensors are disposed in the loading mechanism and the test section, and each sensor is communicated with the monitoring system 3. The sensor comprises a force sensor, a mass flow meter, a displacement sensor, an acceleration sensor, a temperature sensor and a cavity pressure sensor. Wherein: and a force sensor is arranged at the joint of the loading mechanism 2 and the loading rod 27. A low-temperature medium mass flowmeter is arranged at the low-temperature medium inlet 29. The displacement sensor, the acceleration sensor, the temperature sensor and the cavity pressure sensor respectively pass through sensor through holes on the low-temperature cavity shell 8, the first load applying part 23 and the second load applying part 24 and are arranged on the upper end face of the test bearing 20 retainer. Temperature sensors are respectively installed in the upper support bearing 31 and the lower support bearing 32, and the temperature sensors are installed through sensor through holes on the main shaft shell 8 and the temperature adjusting water jacket 17.

In the test chamber, a load application assembly 22 is mounted in the cryogenic chamber. The deflector 37 is positioned in the load applying assembly 22, fixed to the upper end surface of the machine spindle 19, and the lower end surface of the deflector 37 is fitted to the upper end surface of the machine spindle 19 and the upper end surface of the pressing cover 21. And a low-temperature cavity sealing end cover 10 is arranged on the upper end surface of the low-temperature cavity shell 8.

The oil-gas lubrication cavity comprises a main shaft shell 11, a temperature adjusting water jacket 17, a main shaft rear end cover 15, an inner spacer ring 34, an outer spacer ring 35 and a bearing spacer ring 36. The mechanical main shaft 19 penetrates through the oil-gas lubrication cavity, and the connecting section of the mechanical main shaft 19 and the driving motor 1 is located outside the lower end surface of the oil-gas lubrication cavity. The inner spacer 34 is positioned in the oil-gas lubrication cavity and is sleeved on the outer circumferential surface of the mechanical main shaft 19; the outer spacer 35 is fitted over the outer circumferential surface of the inner spacer 34 with a gap of 4mm between the outer circumferential surface of the inner spacer 34 and the inner circumferential surface of the outer spacer 35, forming the upper section of the lubricant flow passage. The temperature adjusting water jacket 17 is positioned in the main shaft shell 11 and is sleeved on the outer circumferential surface of the outer space ring 35, and the outer surface of the temperature adjusting water jacket 17 is in interference fit with the inner surface of the main shaft shell 11; a flow passage for the temperature adjusting medium is formed by a temperature adjusting medium passage 18 located on the outer surface of the temperature adjusting water jacket 17. The inner surface of the temperature adjusting water jacket 17 is in interference fit with the outer surface of the outer spacer ring 35, the outer surface of a support bearing sleeved on the machine main shaft 19 and the outer surface of the bearing spacer ring 36.

The support bearings include two upper support bearings 31 and two lower support bearings 32; the upper bearing 31 is located at the upper end in the oil-gas lubrication cavity, and the lower bearing 32 is located at the lower end in the oil-gas lubrication cavity. The upper support bearing 31 and the lower support bearing 32 are both sleeved on the machine main shaft 19, the upper support bearing 31 is positioned above the inner spacer 34 and the outer spacer 35, and the lower support bearing 32 is positioned below the inner spacer 34 and the outer spacer 35. A bearing spacer ring 36 is installed between the two upper support bearings 31, and a bearing spacer ring 36 is also installed between the two lower support bearings 32.

The combined sealing structure 4 is sleeved on the upper end of the machine spindle 19, is positioned below the first load applying part 23 in the load applying assembly 22, and is fixed on the upper end face of the spindle housing 11. The leaf seal wheel 7 in the combined seal structure 4 is in key connection with the mechanical main shaft 19. A spacer 38 is installed between the upper surface of the packing wheel 7 and the test bearing 20 in the first load applying member 23, the upper surface of the spacer 38 is in interference fit with the lower surface of the inner race of the test bearing 20, the lower surface of the spacer 38 is in interference fit with the upper surface of the packing wheel 7, and the inner circumferential surface of the spacer 38 is in interference fit with the outer circumferential surface of the machine spindle 19; the mutual friction between the leaf seal wheel 7 and the test bearing 20 is prevented by said spacer 38.

The main shaft rear end cover 15 is fixed to the lower end surface of the main shaft housing 11, and the main shaft housing 11 and the temperature adjusting water jacket 17 are fixed by the main shaft rear end cover 15. The rear end cover 15 of the main shaft is annular. The inner diameter of the end of the main shaft rear end cover 15 connected with the main shaft shell 11 is larger than the outer diameter of the locking nut 33, and a lower section of a lubricating medium flow passage is formed between the inner surface of the main shaft rear end cover 15 and the outer surface of the locking nut 33; the outer diameter of the end of the main shaft rear end cover 15 connected with the main shaft shell 11 is the same as the inner diameter of the temperature adjusting water jacket 17. The other end of the main shaft rear end cover 15 has a flange connected to the main shaft housing 11. The inner surface of the central hole of the flange end of the main shaft rear end cover 15 is provided with a radial sealing groove. Four lubricating medium outlets 16 are uniformly distributed on the periphery of the central hole of the flange end, and each lubricating medium outlet 16 is communicated with a lubricating medium flow channel in the oil-gas lubricating cavity body; the center line of each lubricating medium outlet 16 is parallel to the center line of the main shaft rear end cover 15.

The inner circumferential surface of the upper end of the spindle housing 11 is provided with a positioning spigot matched with the lower surface of the step on the outer end surface of the temperature adjusting water jacket 17. The outer circumferential surface of the spindle housing 11 has a shape matching that of a support bracket to be fitted thereto. A temperature adjusting medium outlet 13 is arranged on the shell at the upper end of the spindle shell 11, and the temperature adjusting medium outlet 13 is communicated with a temperature adjusting medium flow channel formed by the temperature adjusting medium channel 18; the center line of the temperature adjusting medium outlet 13 is perpendicular to the outer surface of the temperature adjusting water jacket 17. A temperature adjusting medium inlet 12 is formed in the housing at the lower end of the main shaft housing 22, and the temperature adjusting medium inlet 12 is communicated with a flow passage of a temperature adjusting medium formed by the temperature adjusting medium passage 18; the center line of the temperature adjusting medium inlet 12 is perpendicular to the outer surface of the temperature adjusting water jacket 17. Eight lubricating medium inlets 14 with the inner diameter of 8mm are uniformly distributed on the circumference of the shell at the upper end of the main shaft shell 11, and each lubricating medium inlet 14 is communicated with the inner cavity of the upper supporting bearing 31 positioned at the upper end of the mechanical main shaft 19, so that the lubricating medium enters the inner cavity of the upper supporting bearing 31 and further enters the inner cavity of the lower supporting bearing 32 positioned at the lower end of the mechanical main shaft 19 from the upper section of a lubricating medium flow channel positioned in the oil-gas lubricating cavity. The inner cavity of the lower support bearing 32 communicates with the lower section of the flow passage for the lubricating medium.

The lubricating medium flow passage is composed of an inner cavity of the upper supporting bearing 31, an inner cavity of the lower supporting bearing 32, an inner cavity of the bearing spacer ring 36, an upper section of the lubricating medium flow passage and a lower section of the lubricating medium flow passage. The upper section of the lubricating medium flow channel is positioned between the supporting bearings at the upper end and the lower end of the outer spacer ring 35 and is formed by an annular cavity between the inner surface of the outer spacer ring 35 and the outer surface of the inner spacer ring 34; the distance between the inner surface of the outer spacer 35 and the outer surface of the inner spacer 34 is 4 mm. The lower section of the lubricating medium flow channel is positioned below the lower support bearing 32 at the lower end of the outer spacer 35 and is formed by an annular cavity between the outer surface of the locking nut 33 below the lower support bearing 32 and the inner surface of the sleeve of the main shaft rear end cover 15; the minimum distance between the outer surface of the locking nut 33 and the inner surface of the sleeve is 12 mm. The locking nut 33 is sleeved on the mechanical main shaft 19.

The outer space ring 35 is a hollow rotary body, the inner diameter of the outer space ring is 4mm larger than the outer diameter of the inner space ring 34, the outer diameter of the outer space ring 35 is the same as the inner diameter of the temperature adjusting water jacket 17, and the outer space ring and the temperature adjusting water jacket are in interference fit. The upper end surface of the outer space ring 35 is attached to the lower end surface of the upper bearing 31; the lower end surface of the outer spacer 35 is attached to the upper end surface of the lower support bearing 32. The wall thickness of the outer cage 35 is 20 mm.

The inner spacer 34 is also a hollow rotator, and its inner diameter is the same as the outer diameter of the machine spindle 19, so that the two are in interference fit. The upper end surface of the inner spacer 34 is attached to the lower end surface of the upper support bearing 31; the lower end face of the inner spacer 34 is attached to the upper end face of the lower support bearing 32. The wall thickness of the inner spacer 34 is 6 mm.

The upper support bearing 31 is composed of two ball bearings; the two bearings are axially aligned. Between which a bearing spacer ring 36 is mounted. The lower support bearing 32 is also composed of two ball bearings; the two bearings are axially aligned. A bearing spacer ring 36 is also mounted between the two bearings. Each of the bearing spacer rings 36 is divided into an inner ring and an outer ring, and the inner diameter of the outer ring is 1.5mm larger than the outer diameter of the inner ring, and a flow passage of a lubricating medium is formed by an annular cavity between the inner surface of the outer ring and the outer surface of the inner ring. Bosses which are attached to the end faces of the matched supporting bearings are respectively arranged at the outer edges of the upper end faces of the outer rings of the bearing spacing rings 36 and the outer edges of the lower end faces of the outer rings of the bearing spacing rings 36, and concave faces are respectively formed on the upper end faces and the lower end faces of the outer rings of the bearing spacing rings 36; the concave surfaces form a flow channel for the lubricating medium.

The combined sealing structure 4 comprises a separating disc 5, a sealing disc 6 and a leaf sealing wheel 7, and the separating disc 5, the sealing disc 6 and the leaf sealing wheel 7 are all sleeved on the mechanical main shaft 19, wherein: the separating disc 5 is fixed on the upper end surface of the main shaft shell 11 through bolts; the inner surface of the separation disc 5 is in clearance fit with the outer surface of the machine spindle 19, and two axially arranged annular seal grooves are formed between the inner surface of the separation disc 5 and the outer surface of the machine spindle 19. The sealing disc 6 is fixed on the upper end surface of the separating disc 5 through bolts; the inner surface of the gland plate 6 is in clearance fit with the outer surface of the machine spindle 19 and forms an annular seal between the inner surface of the gland plate 6 and the outer surface of the machine spindle 19. A sealing ring mounting groove is formed between the surfaces of the sealing disc 6 and the separating disc 5 which are attached to each other; a seal ring mounting groove is also formed between the separation disc 6 and the upper end surface of the main shaft housing 11. The blade sealing wheel 7 is in key connection with the mechanical main shaft 19, so that the blade sealing wheel 7 can rotate along with the mechanical main shaft 19; the lower end of the impeller 7 is positioned in a groove on the upper surface of the seal disk 6, and the outer circumferential surface of the impeller 7 is in clearance fit with the inner circumferential surface of the seal disk 6; the labyrinth seal between the seal disc 6 and the leaf seal wheel 7 is formed by annular seal grooves axially arranged on the inner surface of the groove of the seal disc 6. In the embodiment, the combined sealing structure 4 realizes combined sealing in three forms of blade seal wheel sealing, labyrinth sealing and sealing ring sealing, can effectively prevent leakage and exchange of low-temperature media and lubricating media, and realizes interface sealing between ultralow-temperature high pressure and normal-temperature low pressure; meanwhile, the combined sealing structure 4 is compact in design and saves space.

The separating disk 5 is in the shape of a disk, and the center of the separating disk 5 is provided with a through hole of the mechanical main shaft 19, and a clearance fit is formed between the two. The inner circumferential surface of the separating disc 5 is provided with a radial groove, a sealing ring is arranged in the groove and is fastened by a sealing ring gland; the sealing ring gland is fixed on the upper surface of the separating disc 5; there is also a sealing ring groove on the lower surface of the separation disc 5. Eight grooves are uniformly distributed on the lower surface of the sealing disc 5, and the grooves are communicated with the lubricating medium inlet 14 and the inner cavity of the upper supporting bearing 31, so that the lubricating medium can pass through the grooves conveniently.

The sealing disk 6 is also hollow disk-shaped. The upper surface of the sealing disc 6 is a stepped surface and is provided with a groove for placing the leaf sealing wheel 7. The outer edge of the lower surface of the sealing disc 6 is provided with a positioning boss which axially protrudes, and the inner diameter of the positioning boss is the same as the outer diameter of the separation disc 5; a seal groove for mounting a seal ring is provided on the lower surface of the seal disk 6. The inner surface of the sealing disc 6 is in clearance fit with the outer surface of the machine spindle 19. A radial groove for installing a sealing ring is arranged on the inner circumferential surface of the sealing disc 6; the sealing ring gland is fixed on the upper surface of the sealing disc 6, and the sealing ring is fastened through the sealing ring gland.

The leaf seal wheel 7 adopts the prior art. The inner circumferential surface of the leaf seal wheel 7 is provided with a groove for key connection with the mechanical main shaft 19.

The load applying assembly 22 includes a first load applying member 23, a second load applying member 24, a third load applying member 25, and a load bearing 26. Wherein: the third load applying member 25 is positioned at the upper end of the second load applying member 24 and fixedly coupled thereto by a bolt. The first load applying member 23 is located at a lower end of the second load applying member 24 and is fixedly coupled thereto by a bolt. Two load bearings 26 are located within the third load applying member 25. The lower end of the loading rod 27 is fitted into the loading bearing 26 and extends into the shaft hole at the upper end of the second load applying member 24. A loading bush 30 is installed between the shaft hole surface of the upper end of the second load applying member 24 and the outer circumferential surface of the loading rod 27. The outer circumferential surface of the loading bush 30 is interference-fitted with the inner surface of the shaft hole of the upper end of the second load applying member 24, and the inner circumferential surface of the loading bush 30 is clearance-fitted with the outer circumferential surface of the loading lever 27. The test bearing 20 is seated in the first load applying member 23. During the test, the loading mechanism 2 applies a pulling force to the loading rod 27; the load bar 27 transmits the force to the third load applying member 25 through the load bearing 26, and then to the test bearing 20 through the second load applying member 24 and the first load applying member 23, thereby completing the loading.

The first load applying member 23 is annular. The inner circumferential surface of the lower end of the first load applying member 23 has a radially protruding positioning spigot for positioning and load application of the test bearing 20. The first load applying member 23 has the same outer diameter as the maximum outer diameter of the second load applying member 24, and the first load applying member 23 has the same inner diameter as the outer diameter of the outer ring of the test bearing 20.

The second load applying member 24 is cylindrical. The second load applying member 24 has an open lower end and an end cap at an upper end, and the end cap has a mounting hole of the loading rod 27 at the center thereof, the mounting hole having an inner diameter identical to the outer diameter of the loading bush 30; the inner diameter of the loading bush 30 is the same as the outer diameter of the loading rod 27; the load bar 27 is in clearance fit with the load bushing 30, and the load bushing 30 is in interference fit with the central load bar mounting hole of the end cap. The outer circumferential surface of the lower end of the second load applying member 24 is stepped, and a positioning spigot that fits with the first load applying member 23 is formed at the lower end of the second load applying member 24. The second load applying member 24 has an inner diameter larger than the maximum outer diameter of the flow guide head 37, and a flow passage for the low temperature medium is formed between the flow guide head 37 and the inner surface of the second load applying member 24.

The third load applying member 25 is also cylindrical. The third load applying member 25 has an open lower end, and a flange connected to the second load applying member 24 is formed on an outer circumferential surface of the lower end; the third load applying member 25 has a mounting hole for the load lever 27 at the center of the upper end cap. The third load applying member 25 has the same inner diameter as the outer diameter of the outer race of the load bearing 26.

The loading rod 27 is a hollow rod with one end closed. The inner hole of the loading rod 27 is a flow passage of the low-temperature medium, and a low-temperature medium inlet 29 is arranged on the loading rod 27. The center of the lower opening of the loading rod 27 corresponds to the center of the flow guide head 37 fixed on the upper end surface of the machine spindle 19. A loading force transmission boss 28 protruding in the radial direction is provided on the outer circumferential surface of the loading rod 27 near the lower end thereof; the upper surface of the loading force-transmission boss 28 is attached to the lower surface of the loading bearing 26; the loading force transfer boss 28 has the same outer diameter as the inner race of the loading bearing 26.

The test shafting comprises a mechanical main shaft 19, a gland 21, a test bearing 20 and a support bearing. The mechanical main shaft 19 penetrates through the oil-gas lubrication cavity, the front end of the mechanical main shaft 19 is located in the low-temperature cavity, and the lower end of the mechanical main shaft 19 penetrates through the main shaft rear end cover 15 and is located outside the oil-gas lubrication cavity; the part of the mechanical main shaft 19, which is positioned in the low-temperature cavity, is provided with a test bearing 20; the gland 21 is sleeved and fixed on the upper end of the machine main shaft 19, and the test bearing 20 is positioned through the gland 21. A flow guide head 37 is connected to an upper end surface of the machine spindle 19, and the low-temperature medium is introduced into the test bearing 20 through the flow guide head 37. The lower end of the mechanical main shaft 19 in the oil-gas lubrication cavity is supported by two groups of supporting bearings. The machine spindle 19 is connected to the drive motor 1 via a coupling. The test bearing 20 is positioned in the load applying assembly 22 such that the outer circumferential surface of the outer race of the test bearing 20 is in clearance fit with the inner circumferential surface of the first load applying member 23 of the load applying assembly 22. The support bearings include two upper support bearings 31 and two lower support bearings 32; the upper bearing 31 is located at the upper end in the oil-gas lubrication cavity, and the lower bearing 32 is located at the lower end in the oil-gas lubrication cavity. The upper support bearing 31 and the lower support bearing 32 are both sleeved on the machine main shaft 19, the upper support bearing 31 is positioned above the inner spacer 34 and the outer spacer 35, and the lower support bearing 32 is positioned below the inner spacer 34 and the outer spacer 35. A bearing spacer ring 36 is installed between the two upper support bearings 31, and a bearing spacer ring 36 is also installed between the two lower support bearings 32.

The appearance of the flow guide head 37 is designed according to the analysis of the low-temperature cavity flow field, so that the low-temperature medium can be better guided to the test bearing 20, and the cooling effect is improved. In this embodiment, the flow guide head 37 is a rotary body. The outer circumferential surface of the upper end of the flow guide head 37 is a conical section; the taper of the conical section is 102 degrees. The center of the lower surface of the conical section is provided with an axial equal diameter section, and the diameter of the equal diameter section is the same as the outer diameter of the gland 21. The center of the lower end surface of the flow guide head 37 is provided with a connecting rod which axially protrudes. The connecting rod is installed in a threaded hole in the upper end face of the mechanical main shaft 19 through threads.

The temperature adjusting water jacket 17 is sleeve-shaped. The inner diameter of the temperature adjusting water jacket 17 is the same as the outer diameter of the outer space ring 35, and the two are in interference fit; the temperature adjusting water jacket 17 has the same outer diameter as the spindle housing 11 and is in interference fit therewith. A spiral temperature adjusting medium passage 18 is provided on the outer circumferential surface of the temperature adjusting water jacket 17. The temperature-adjusting medium passage 18 has a rectangular cross section with a width of 18mm, a depth of 5mm, and a helix angle of 5 °.

In the embodiment, the main shaft 19 of the oil-gas lubricated high-speed heavy-load machine drags the test bearing 20 to rotate, the test bearing 20 is in the low-temperature cavity in the ultralow-temperature environment, and the support bearing is in the oil-gas lubricated cavity at the normal temperature, so that the service life of the support bearing is prolonged compared with the arrangement mode that the tested bearing and the support process bearing in retrieval documents are both in the low-temperature medium, and the long-time test of the test device on the ultralow-temperature test bearing 20 can be realized.

The cryogenic medium enters the loading rod 27 from the cryogenic medium inlet 29 and flows into the cryogenic chamber inner chamber, then flows directly to the test bearing 20 through the flow guide head 37, then flows into the cryogenic chamber outer chamber and completely submerges the test bearing 20, and finally exits through the cryogenic medium outlet 9, thereby simulating an ultra-low temperature environment.

The lubricating medium enters from the lubricating medium inlet 14, flows through the two upper supporting bearings 31 and the bearing spacer ring 36 between the two upper supporting bearings, the upper section of the lubricating medium flow passage, the lower supporting bearing 32 and the bearing spacer ring 36 between the two lower supporting bearings and the lower section of the lubricating medium flow passage in sequence, and is finally discharged from the lubricating medium outlet 16, so that the supporting bearings are lubricated, and the service life of the supporting bearings is guaranteed.

The temperature adjusting medium enters from the temperature adjusting medium inlet 12, flows through the spiral temperature adjusting medium channel 18 on the surface of the temperature adjusting water jacket 17, and is finally discharged from the temperature adjusting medium outlet 13, so that the temperature of the oil-gas lubricating cavity is kept at the optimal working temperature of the lubricating medium, and the oil-gas lubricating effect is ensured.

The specific process of utilizing the ultra-low temperature bearing life test device to test provided by the embodiment is as follows:

step one, determining low-temperature medium flow and lubricating medium flow parameters of the test bearing 20 according to the requirements of the rotating speed and the load provided by the test outline;

in this example, the rotation speed of the test bearing 20 was set to 18000rpm and the load was set to 2000 kgf; the flow rate of the low-temperature medium is set to be 10kg/s, and the flow rate of the lubricating medium is set to be 0.03 ml/min.

And step two, assembling the test bearing 20. The test bearing 20 is mounted on the machine spindle 19 and secured by a gland 21. The flow guide head 37 is attached to the upper end surface of the machine spindle 19.

And step three, starting a low-temperature medium source, and introducing a low-temperature medium with the flow rate of 1kg/s into the low-temperature cavity through the hollow loading rod 27 to pre-cool the low-temperature cavity. And when the temperature of the low-temperature cavity reaches-196 ℃, closing the low-temperature medium source and ending precooling. The low-temperature medium is liquid nitrogen.

Fourthly, adjusting parameters of a loading mechanism 2 according to the rotating speed and the load provided by the test outline, and applying the load to the test bearing 20 through the loading mechanism 2; the applied load simulates the load experienced by the test bearing 20 under actual operating conditions.

And step five, starting a low-temperature medium source, adjusting the flow of the low-temperature medium to 10kg/s, and simulating a low-temperature environment at the temperature of-196 ℃. Meanwhile, a lubricating medium is introduced into the oil-gas lubricating cavity and is kept until the test is finished, so that lubrication is provided for the mechanical main shaft 19 and the support bearing; the lubricating medium is VG68 lubricating oil.

In order to ensure the oil-gas lubrication effect, when the temperature in the oil-gas lubrication cavity is higher than the optimal working temperature of a lubrication medium, liquid nitrogen is introduced into the temperature adjusting water jacket 17 through the temperature adjusting medium inlet 12 for cooling, so that the temperature in the oil-gas lubrication cavity is kept at 40 ℃; when the temperature of the oil-gas lubrication cavity is lower than the optimal working temperature of the lubrication medium, water is introduced into the temperature adjusting water jacket 17 through the temperature adjusting medium inlet 12 to raise the temperature, and the temperature of the oil-gas lubrication cavity is kept constant at 40 ℃.

And step six, starting the driving motor 1, enabling the rotating speed of the test bearing 20 to reach 18000rpm, driving the mechanical main shaft 19 to rotate by the driving motor 1, further driving the test bearing 20 to rotate, and simulating the working rotating speed of the test bearing 20 until data acquisition is completed.

Seventhly, monitoring the running state of the test device through the monitoring system 3 and recording test data; the test data includes test bearing 20 temperature, test bearing 20 displacement, test bearing 20 acceleration, cavity pressure at the test bearing 20, upper support bearing 31 temperature and lower support bearing 32 temperature.

Step seven, after the required test data is obtained, the driving motor 1 is closed, and the mechanical main shaft 19 stops rotating; stopping introducing the low-temperature medium, the lubricating medium and the temperature adjusting medium; closing the loading mechanism 2; the test bearing 20 is removed and the test is completed.

Claims

1. An ultra-low temperature rolling bearing service life testing device is characterized by comprising a driving motor, a loading mechanism, a monitoring system and a testing section; the test section comprises a test cavity and a test shafting, wherein the test cavity is divided into a low-temperature cavity and an oil-gas lubrication cavity; the low-temperature cavity is positioned at the upper end of the oil-gas lubrication cavity and is sealed and isolated from the oil-gas lubrication cavity through a combined sealing structure; the test shaft system is positioned in the test cavity, a mechanical main shaft in the test shaft system penetrates through the oil-gas lubrication cavity, the upper end of the mechanical main shaft is positioned in the low-temperature cavity, and the lower end of the mechanical main shaft penetrates through the main shaft rear end cover and is positioned outside the oil-gas lubrication cavity; the driving motor is connected with the mechanical main shaft; each input port of the monitoring system is respectively communicated with each sensor distributed in the loading mechanism, the test cavity, the test bearing and the support bearing through data lines; the loading mechanism is positioned at the upper end of the low-temperature cavity, and a loading cylinder in the loading mechanism is fixedly connected with a loading rod; the lower end of the loading rod is positioned in the low-temperature cavity and is connected with a third load applying part in the load applying assembly through a loading bearing; the load bearing is located within the third load applying member;

the cavity of the low-temperature cavity consists of a low-temperature cavity shell, a combined sealing structure and a low-temperature cavity sealing end cover, the load applying assembly and the test bearing are both positioned in the cavity of the low-temperature cavity, and the cavity of the low-temperature cavity is divided into an inner cavity and an outer cavity by the load applying assembly and the test bearing, so that a double-layer structure is formed; the test bearing is sleeved at the upper end of the mechanical main shaft and is positioned in a first load applying part of the load applying assembly; the flow guide head is positioned in the load applying assembly and fixed on the upper end surface of the mechanical main shaft, and the lower end surface of the flow guide head is attached to the upper end surface of the mechanical main shaft and the upper end surface of the gland; a low-temperature cavity sealing end cover is arranged on the upper end surface of the low-temperature cavity shell; the test bearing is positioned in the low-temperature cavity and sleeved on the mechanical main shaft; the low-temperature cavity shell is provided with a low-temperature medium outlet;

the oil-gas lubrication cavity comprises a main shaft shell, a temperature regulation water jacket, a main shaft rear end cover, an inner spacer ring, an outer spacer ring and a bearing spacer ring; the inner spacer is positioned in the oil-gas lubrication cavity and sleeved on the outer circumferential surface of the mechanical main shaft; the outer space ring is sleeved on the outer circumferential surface of the inner space ring, and a gap of 4mm is formed between the outer circumferential surface of the inner space ring and the inner circumferential surface of the outer space ring, so that the upper section of a lubricating medium flow channel is formed; the temperature adjusting water jacket is positioned in the main shaft shell and sleeved on the outer circumferential surface of the outer space ring, and the outer surface of the temperature adjusting water jacket is in interference fit with the inner surface of the main shaft shell; a temperature adjusting medium passage located on the outer surface of the temperature adjusting water jacket forms a flow passage of a temperature adjusting medium; the inner surface of the temperature adjusting water jacket is in interference fit with the outer surface of the outer space ring, the outer surface of a support bearing sleeved on the mechanical main shaft and the outer surface of the bearing space ring.

2. An ultra-low temperature rolling bearing life test device as claimed in claim 1, wherein the combined sealing structure comprises a separating disc, a sealing disc and a leaf seal wheel, and the separating disc, the sealing disc and the leaf seal wheel are all sleeved on the mechanical main shaft, wherein: the separation disc is fixed on the upper end face of the main shaft shell; the inner surface of the separating disc is in clearance fit with the outer surface of the mechanical spindle, and two annular sealing grooves which are axially arranged are formed between the inner surface of the separating disc and the outer surface of the mechanical spindle; the sealing disc is fixed on the upper end surface of the separating disc; the inner surface of the sealing disc is in clearance fit with the outer surface of the mechanical main shaft, and an annular sealing groove is formed between the inner surface of the sealing disc and the outer surface of the mechanical main shaft; a sealing ring mounting groove is formed between the surfaces of the sealing disc and the separating disc, which are attached to each other; a sealing ring mounting groove is also formed between the separating disc and the upper end surface of the main shaft shell; the blade sealing wheel is connected with the mechanical main shaft through a key, so that the blade sealing wheel can rotate along with the mechanical main shaft; the lower end of the leaf seal wheel is positioned in the groove on the upper surface of the seal disc, and the outer circumferential surface of the leaf seal wheel is in clearance fit with the inner circumferential surface of the seal disc; and the annular sealing groove which is axially arranged on the inner surface of the sealing disc groove forms a labyrinth seal between the sealing disc and the blade seal wheel; a spacer is installed between the upper surface of the impeller and the test bearing in the first load applying member, and an inner circumferential surface of the spacer is in interference fit with an outer circumferential surface of the machine spindle.

3. The ultra-low temperature rolling bearing life test apparatus of claim 1, wherein the load applying assembly includes a first load applying member, a second load applying member, a third load applying member and a loading bearing; wherein: the third load applying piece is positioned at the upper end of the second load applying piece and fixedly connected with the second load applying piece through a bolt; the first load applying piece is positioned at the lower end of the second load applying piece and fixedly connected with the second load applying piece through a bolt; two load bearings are located within the third load applying member; the lower end of the loading rod is arranged in the loading bearing and extends into a shaft hole at the upper end of the second load applying piece; a loading bush is arranged between the surface of the shaft hole at the upper end of the second load applying part and the outer circumferential surface of the loading rod; the outer circumferential surface of the loading bush is in interference fit with the inner surface of the shaft hole at the upper end of the second load applying member, and the inner circumferential surface of the loading bush is in clearance fit with the outer circumferential surface of the loading rod; the test bearing is placed in the first load applying member; during testing, the loading mechanism applies tension to the loading rod; the loading rod transmits force to the third load applying part through the loading bearing, and then transmits the force to the test bearing through the second load applying part and the first load applying part to finish loading;

the inner circumferential surface of the lower end of the first load applying member is provided with a positioning spigot which protrudes radially and is used for positioning and applying load of a test bearing; the outer diameter of the first load applying member is the same as the maximum outer diameter of the second load applying member, and the inner diameter of the first load applying member is the same as the outer diameter of the test bearing outer ring;

the lower end of the second load applying member is formed with a positioning spigot which is matched with the first load applying member; the inner diameter of the second load applying member is larger than the maximum outer diameter of the flow guide head, and a flow passage of the low-temperature medium is formed between the flow guide head and the inner surface of the second load applying member;

the outer circumferential surface of the lower end of the third load applying part is provided with a flange connected with the second load applying part; the third load applying member has an inner diameter equal to an outer diameter of the loading bearing outer ring.

4. An ultra-low temperature rolling bearing life test device as claimed in claim 1, wherein said sensors include force sensors, mass flow meters, displacement sensors, acceleration sensors, temperature sensors and cavity pressure sensors; wherein: a force sensor is arranged at the joint of the loading mechanism and the loading rod; a low-temperature medium mass flowmeter is arranged at the low-temperature medium inlet; the displacement sensor, the acceleration sensor, the temperature sensor and the cavity pressure sensor respectively penetrate through sensor through holes in the low-temperature cavity shell, the first load applying part and the second load applying part and are arranged on the upper end face of the test bearing retainer; temperature sensors are respectively arranged in the upper supporting bearing and the lower supporting bearing, and the temperature sensors are arranged in the upper supporting bearing and the lower supporting bearing through sensor through holes on the main shaft shell and the temperature adjusting water jacket.

5. The ultra-low temperature rolling bearing life test device of claim 1, wherein the test shafting comprises a mechanical main shaft, a gland, a test bearing and a support bearing; the gland is sleeved and fixed at the upper end of the mechanical main shaft, and the test bearing is positioned through the gland; the end face of the upper end of the mechanical main shaft is connected with a flow guide head, and a low-temperature medium is guided into the test bearing through the flow guide head; the lower end of the mechanical main shaft in the oil-gas lubricating cavity is supported by two upper supporting bearings and two lower supporting bearings; the mechanical main shaft is connected with a driving motor through a coupler; the test bearing is positioned in the load applying assembly, and the outer circumferential surface of the outer ring of the test bearing is in clearance fit with the inner circumferential surface of the first load applying member in the load applying assembly;

the upper bearing is positioned at the upper end in the oil-gas lubricating cavity, and the lower bearing is positioned at the lower end in the oil-gas lubricating cavity; the upper supporting bearing and the lower supporting bearing are sleeved on the mechanical main shaft, the upper supporting bearing is positioned above the inner spacing ring and the outer spacing ring, and the lower supporting bearing is positioned below the inner spacing ring and the outer spacing ring; a bearing spacing ring is arranged between the two upper supporting bearings, and a bearing spacing ring is also arranged between the two lower supporting bearings; each bearing spacer ring is divided into an inner ring and an outer ring, the inner diameter of the outer ring is 1.5mm larger than the outer diameter of the inner ring, and a flow channel of a lubricating medium is formed by an annular cavity between the inner surface of the outer ring and the outer surface of the inner ring; bosses which are attached to the end faces of the matched supporting bearings are respectively arranged at the outer edges of the upper end faces of the outer rings of the bearing spacing rings and the outer edges of the lower end faces of the outer rings of the bearing spacing rings, and concave faces are respectively formed on the upper end faces and the lower end faces of the outer rings of the bearing spacing rings; the concave surfaces form a flow channel for the lubricating medium.

6. The ultra-low temperature rolling bearing life test device according to claim 1, wherein the main shaft rear end cap is fixed on the lower end surface of the main shaft housing, and the main shaft housing is fixed with the temperature adjusting water jacket through the main shaft rear end cap; a lower section of a lubricating medium flow channel is formed between the inner surface of the rear end cover of the main shaft and the outer surface of the locking nut; the outer diameter of one end of the main shaft rear end cover connected with the main shaft shell is the same as the inner diameter of the temperature adjusting water jacket; the inner surface of the central hole of the flange end of the main shaft rear end cover is provided with a radial sealing groove; four lubricating medium outlets are uniformly distributed on the periphery of the central hole of the flange end, and each lubricating medium outlet is communicated with a lubricating medium flow channel in the oil-gas lubricating cavity; the central line of each lubricating medium outlet is parallel to the central line of the rear end cover of the main shaft.

7. An ultra-low temperature rolling bearing life test device according to claim 1, wherein a temperature adjusting medium outlet is formed at an upper end of the main shaft housing and is communicated with a flow passage of a temperature adjusting medium formed by the temperature adjusting medium passage; the central line of the temperature adjusting medium outlet is vertical to the outer surface of the temperature adjusting water jacket; a temperature adjusting medium inlet is arranged on the shell at the lower end of the main shaft shell, and the temperature adjusting medium inlet is communicated with a flow channel of a temperature adjusting medium formed by the temperature adjusting medium channel; the central line of the temperature adjusting medium inlet is vertical to the outer surface of the temperature adjusting water jacket; eight lubricating medium inlets with the inner diameter of 8mm are uniformly distributed on the circumference of the shell at the upper end of the main shaft shell, and each lubricating medium inlet is communicated with the inner cavity of the upper supporting bearing at the upper end of the mechanical main shaft, so that a lubricating medium enters the inner cavity of the upper supporting bearing and further enters the inner cavity of the lower supporting bearing at the lower end of the mechanical main shaft from the upper section of a lubricating medium flow channel in the oil-gas lubricating cavity; and the inner cavity of the lower supporting bearing is communicated with the lower section of the lubricating medium flow passage.

8. The ultra-low temperature rolling bearing life test device according to claim 1, wherein the lubricating medium flow passage is composed of an inner cavity of the upper support bearing, an inner cavity of the lower support bearing, an inner cavity of the bearing spacer ring, an upper section of the lubricating medium flow passage and a lower section of the lubricating medium flow passage; the upper section of the lubricating medium flow channel is positioned between the supporting bearings at the upper end and the lower end of the outer space ring and consists of a circular cavity between the inner surface of the outer space ring and the outer surface of the inner space ring; the distance between the inner surface of the outer spacing ring and the outer surface of the inner spacing ring is 4 mm; the lower section of the lubricating medium flow channel is positioned below the supporting bearing at the lower end of the outer space ring and is formed by an annular cavity between the outer surface of a locking nut below the lower supporting bearing and the inner surface of a sleeve of the rear end cover of the main shaft; the minimum distance between the outer surface of the locking nut and the inner surface of the sleeve is 12 mm; the locking nut is sleeved on the mechanical main shaft;

the outer space ring is a hollow revolving body, the inner diameter of the outer space ring is 4mm larger than the outer diameter of the inner space ring, the outer diameter of the outer space ring is the same as the inner diameter of the temperature adjusting water jacket, and the outer space ring and the temperature adjusting water jacket are in interference fit; the upper end surface of the outer space ring is attached to the lower end surface of the upper supporting bearing; the lower end face of the outer space ring is attached to the upper end face of the lower supporting bearing; the wall thickness of the outer space ring is 20 mm;

the inner spacer is also a hollow revolving body, the inner diameter of the inner spacer is the same as the outer diameter of the mechanical main shaft, and the inner spacer and the mechanical main shaft are in interference fit; the upper end surface of the inner spacer is attached to the lower end surface of the upper supporting bearing; the lower end face of the inner spacer is attached to the upper end face of the lower support bearing; the wall thickness of the inner spacer ring is 6 mm.

9. The ultra-low temperature rolling bearing life test device according to claim 1, wherein the loading rod is a hollow rod with one end closed; the inner hole of the loading rod is a flow channel of a low-temperature medium, and a low-temperature medium inlet is formed in the loading rod; the center of the lower end opening of the loading rod corresponds to the center of a flow guide head fixed on the upper end surface of the mechanical main shaft; a loading force transmission boss which is radially protruded is arranged on the outer circumferential surface close to the lower end of the loading rod; the upper surface of the loading force transmission boss is attached to the lower surface of the loading bearing; the outer diameter of the loading force transmission boss is the same as that of the loading bearing inner ring; the loading rod is provided with a low-temperature medium inlet;

the outer circumferential surface of the upper end of the flow guide head is a conical section; the taper of the conical section is 102 degrees; the center of the lower surface of the conical section is provided with an axial equal-diameter section, and the diameter of the equal-diameter section is the same as the outer diameter of the gland; the center of the lower end surface of the flow guide head is provided with a connecting rod connected with the mechanical main shaft;

the inner diameter of the temperature adjusting water jacket is the same as the outer diameter of the outer space ring, and the temperature adjusting water jacket and the outer space ring are in interference fit; the outer diameter of the temperature adjusting water jacket is the same as that of the main shaft shell, and the temperature adjusting water jacket and the main shaft shell are in interference fit; a spiral temperature adjusting medium channel is arranged on the outer circumferential surface of the temperature adjusting water jacket; the temperature-adjusting medium passage was rectangular in cross section, 18mm in width, 5mm in depth, and 5 ° in helix angle.

10. A method for carrying out a loading test by using the ultra-low temperature rolling bearing service life test device of claim 1 is characterized by comprising the following specific processes:

step one, determining low-temperature medium flow and lubricating medium flow parameters of the test bearing according to the requirements of the rotating speed and the load provided by the test outline; the set rotation speed of the test bearing was 18000rpm, and the load was 2000 kgf;

the set low-temperature medium flow is 10kg/s, and the lubricating medium flow is 0.03 ml/min;

step two, assembling a test bearing; mounting a test bearing on a mechanical main shaft and fixing the test bearing through a gland; installing a flow guide head on the upper end surface of a mechanical main shaft;

starting a low-temperature medium source, and introducing a low-temperature medium with the flow rate of 1kg/s into the low-temperature cavity through a hollow loading rod to pre-cool the low-temperature cavity; when the temperature of the low-temperature cavity reaches-196 ℃, closing the low-temperature medium source, and ending precooling; the low-temperature medium is liquid nitrogen;

adjusting parameters of a loading mechanism according to the rotating speed and the load provided by the test outline, and applying the load to the test bearing through the loading mechanism; the applied load simulates the load borne by the test bearing under the actual working condition;

step five, starting a low-temperature medium source, adjusting the flow of the low-temperature medium to 10kg/s, and simulating a low-temperature environment at the temperature of-196 ℃; meanwhile, introducing a lubricating medium into the oil-gas lubricating cavity and keeping the oil-gas lubricating cavity until the test is finished, so as to provide lubrication for the mechanical main shaft and the support bearing; the lubricating medium is VG68 lubricating oil;

in order to ensure the oil-gas lubrication effect, when the temperature in the oil-gas lubrication cavity is higher than the optimal working temperature of a lubrication medium, liquid nitrogen is introduced into the mechanical water jacket through the temperature regulation medium inlet to reduce the temperature, so that the temperature in the oil-gas lubrication cavity is kept at 40 ℃; when the temperature of the oil-gas lubrication cavity is lower than the optimal working temperature of the lubrication medium, water is introduced into the mechanical water jacket through the temperature regulation medium inlet to raise the temperature, and the temperature of the oil-gas lubrication cavity is kept constant at 40 ℃;

step six, starting a driving motor, enabling the rotating speed of the test bearing to reach 18000rpm, driving the mechanical spindle to rotate by the driving motor, further driving the test bearing to rotate, and simulating the working rotating speed of the test bearing until data acquisition is completed;

monitoring the running state of the test device through a monitoring system and recording test data; the test data comprises test bearing temperature, test bearing displacement, test bearing acceleration, cavity pressure at the test bearing, upper support bearing temperature and lower support bearing temperature;