CN114646465B

CN114646465B - Multifunctional rolling point contact fatigue life testing machine with variable working conditions

Info

Publication number: CN114646465B
Application number: CN202210270502.0A
Authority: CN
Inventors: 王黎钦; 林飞虎; 张传伟; 王伟; 郑德志; 赵小力; 王小康
Original assignee: Harbin Institute of Technology
Current assignee: Harbin Institute of Technology
Priority date: 2022-03-18
Filing date: 2022-03-18
Publication date: 2023-05-30
Anticipated expiration: 2042-03-18
Also published as: CN114646465A

Abstract

A multifunctional rolling point contact fatigue life testing machine with variable working conditions relates to the field of bearing fatigue life tests. The invention solves the problems that the existing ball bat fatigue testing machine cannot meet the requirements of running test bars under the conditions of high temperature, high speed and different lubrication, and the fatigue life of bearing parts cannot be tested by the replaceable fixture. The test bar and the special fixture are detachably arranged on the driving device, the driving device drives the test bar and the special fixture to realize rotary motion, the driving device drives the test bar and the special fixture to realize longitudinal and/or transverse reciprocating motion under the driving of the lifting centering device, the test core device is positioned below the driving device, the center of the upper end surface of the supporting seat is provided with a circular accommodating groove for accommodating the rolling contact assembly, and the loading device is arranged on the table top of the machine seat and is connected with the gland of the test core device. The invention is used for meeting the requirements of the test bar and the bearing parts running under the conditions of high temperature, high speed and different lubrication.

Description

Multifunctional rolling point contact fatigue life testing machine with variable working conditions

Technical Field

The invention relates to the field of bearing fatigue life tests, in particular to a multifunctional rolling point contact fatigue life testing machine with variable working conditions.

Background

With the continuous progress of aviation industry technology, a main shaft bearing of an aeroengine is used as one of core basic components of the aerospace industry, and key performance indexes such as equipment precision, service life, speed, bearing capacity, service stability and reliability are directly affected. On the premise of realizing a large thrust-weight ratio, the required dn value of the main shaft bearing is increased to 3.0x10 ⁶ The bearing component is more than mm r/min and is always in extremely harsh, complex and changeable service environments, and the requirements on stability and reliability of the bearing component are particularly severe. Compared with the main shaft bearing series of the overseas corresponding bearing steel materials, the conventional aeronautical main shaft bearing in China exists at presentThe service life and reliability of the main shaft bearing are low. Fatigue failure is one of the main failure modes of the bearing, and severely restricts the further improvement of the service life of the bearing.

The rolling contact fatigue life test of the bearing is one of important methods for evaluating the performance of bearing materials, and is a method for applying high cycle contact load to the tested materials until the materials are subjected to fatigue damage. As the rolling contact material is subjected to the repeated action of high contact stress, initial cracks can be initiated at the maximum stress position of the secondary surface, the cracks are expanded to the surface, and finally fatigue stripping is generated, so that the bearing is invalid. The existing testing machine for bearing fatigue life test mainly comprises a ball disc type, a roller type and a bat type, and the rolling contact of the bearing can be divided into two contact modes of line contact and point contact. The bat type rolling contact fatigue testing machine is widely applied due to the simple structure, high rotating speed and closest to the real working form of the bearing.

By simulating the actual working condition of the bearing and eliminating a plurality of influencing factors, a reliable test method is provided for researching the fatigue failure behavior of the bearing material in the actual working condition, the fatigue failure mechanism of the bearing is more fully researched, and the bearing life is improved.

In summary, the existing ball bat fatigue testing machine has the problems that the requirements of the test stick running under the conditions of high temperature, high speed and different lubrication cannot be met, and the fatigue life of the bearing part cannot be tested through the replaceable fixture.

Disclosure of Invention

The invention aims to solve the problems that the existing ball bat fatigue testing machine cannot meet the requirements of running a test bar under high temperature, high speed and different lubrication conditions and the fatigue life of a bearing part cannot be tested through a replaceable clamp, and further provides a multifunctional rolling point contact fatigue life testing machine with variable working conditions.

The technical scheme of the invention is as follows:

the multifunctional rolling point contact fatigue life testing machine with the variable working conditions comprises a machine base 1 and a lifting centering device 2, wherein the lifting centering device 2 is arranged on a table top of the machine base 1; the fatigue life testing machine further comprises a testing core device 3, a loading device 4 and a driving device 5, wherein the driving device 5 is arranged on the lifting centering device 2, the test bar 6 is detachably arranged on the driving device 5, the test bar 6 is driven by the driving device 5 to realize rotary motion, the driving device 5 is driven by the lifting centering device 2 to realize longitudinal reciprocating motion and/or transverse reciprocating motion, and further the test bar 6 is driven to realize lifting motion and/or centering motion, the testing core device 3 is arranged on a table top of the machine base 1, and the testing core device 3 is positioned below the driving device 5; the test core device 3 comprises a supporting seat 31, a gland 32 and a rolling contact assembly, wherein the supporting seat 31 is of a round columnar structure, the supporting seat 31 is vertically arranged on a table top of the machine base 1, and a round accommodating groove 314 for accommodating the rolling contact assembly is formed in the center of the upper end face of the supporting seat 31; the rolling contact assembly comprises an upper loading ring 33, a lower loading ring 34, a gasket 35, a retainer 36 and test accompanying balls 37, wherein the upper loading ring 33, the lower loading ring 34 and the gasket 35 are sequentially and horizontally arranged in a circular accommodating groove 314 of a supporting seat 31 from top to bottom, the supporting seat 31 is in contact with the outer curved surfaces of the upper loading ring 33 and the lower loading ring 34, the gasket 35 is in contact with the inner end surface of the circular accommodating groove 314 of the supporting seat 31, the test accompanying balls 37 are symmetrically distributed around a test bar 6 in the center, the test bar 6 is in point contact with the test accompanying balls 37, the retainer 36 is horizontally arranged between the test bar 6 and the upper loading ring 33 and the lower loading ring 34, three pockets are uniformly formed in the retainer 36 along the circumferential direction, the test accompanying balls 37 are respectively arranged in the three pockets of the retainer 36, the inner side surfaces of the upper loading ring 33 and the lower loading ring 34, which are close to the test accompanying balls 37, the sloping surfaces of the upper loading ring 33 and the lower loading ring 34 are in point contact with the test accompanying balls 37, and gaps exist between the lower end surfaces of the upper loading ring 33 and the upper end surface of the lower loading ring 34; the gland 32 is horizontally arranged right above the supporting seat 31, the gland 32 is connected with the loading device 4, the lower end surface of the gland 32 is contacted with the upper end surface of the upper loading ring 33, and a moving gap exists between the lower end surface of the gland 32 and the upper end surface of the supporting seat 31; the loading device 4 is arranged on the table top of the machine base 1 and is connected with the gland 32 of the test core device 3, the loading device 4 applies load to the test core device 3, the load is applied to the upper loading ring 33 through the gland 32 and then is transferred to the accompanying test ball 37, and finally is transferred to the test rod 6, and the test rod 6 is coaxially and directly driven to rotate through the driving device 5, so that the three-point rolling contact test on the test rod 6 is realized.

Further, the test core device 3 further comprises an oil receiving disc 7, the oil receiving disc 7 is of a disc-shaped structure, the oil receiving disc 7 is horizontally arranged above the gland 32, the oil receiving disc 7 is connected with the gland 32 through bolts, an oil storage groove 71 is machined in the center of the upper end face of the oil receiving disc 7, a test rod assembly through hole 72 is machined in the center of the inner end face of the oil storage groove 71, the aperture of the test rod assembly through hole 72 is 1-2 cm larger than the outer diameter of the test rod 6, and an oil homogenizing groove is machined in the inner end face of the oil storage groove 71 along the radial direction.

Further, the test core device 3 further comprises a magnetic gasket 8, a circular oil-dropping through hole 315 is machined in the center of the inner end face of the circular accommodating groove 314 of the supporting seat 31, an annular step is machined in the inner wall of the upper portion of the circular oil-dropping through hole 315 along the circumferential direction, the magnetic gasket 8 is of an annular plate-shaped structure, the magnetic gasket 8 is horizontally arranged in the circular oil-dropping through hole 315, the magnetic gasket 8 is lapped on the annular step, and the magnetic gasket 8 is in contact with the inner end face of the supporting seat 31.

Further, the test core device 3 further comprises a heating ferrule 9 for heating the contact area, the heating ferrule 9 is sleeved outside the supporting seat 31 and fixedly connected with the supporting seat 31, a first round gland groove for being in clearance fit with the outer side face of the heating ferrule 9 is processed on the lower end face of the gland 32, and a second round gland groove for being in clearance fit with the outer side face of the upper loading ring 33 is processed on the inner end face of the first round gland groove.

Further, the loading device 4 comprises a loader body 41, a pressure arm assembly I42, a pressure arm assembly II 43, a center support assembly 44 and a center support assembly 45;

the pressure arm assembly I42 comprises a first-stage pressure arm 421, a first-stage pressure arm pin roll 423, a pressure lug 424, a shaft pin 425 and two first-stage pressure arm supports 422, wherein the first-stage pressure arm 421 comprises a bending section, a circular ring section and a straight rod section, the bending section, the circular ring section and the straight rod section are sequentially connected from front to back, the end parts of the straight rod sections of the first-stage pressure arm 421 are respectively and rotatably connected with the first-stage pressure arm supports 422 on two sides through the first-stage pressure arm pin roll 423, the bottom ends of the first-stage pressure arm supports 422 are fixedly arranged on the table top of the machine base 1, the top ends of the pressure lug 424 are rotatably connected with the middle parts of the straight rod sections of the first-stage pressure arm 421 through the shaft pin 425, and step holes are formed in the end parts of the bending sections of the first-stage pressure arm 421;

the pressure arm assembly II 43 comprises a second-stage pressure arm 431, two second-stage pressure arm supports 432, two second-stage pressure arm pin shafts 433 and two connecting rods 434, wherein the second-stage pressure arm 431 comprises a U-shaped section and a straight-line section, the middle part of the U-shaped section is connected with the end parts of the straight-line section, the two ends of the U-shaped section of the second-stage pressure arm 431 are respectively and rotatably connected with the second-stage pressure arm supports 432 on the two sides through the second-stage pressure arm pin shafts 433, the bottom ends of the second-stage pressure arm supports 432 are fixed on the table top of the machine base 1, the top ends of the straight-line section of the second-stage pressure arm 431 are contacted with the bottom ends of the pressure lugs 424, the two connecting rods 434 are vertically and oppositely arranged on the front side and the rear side of the supporting seat 31 respectively, the bottom ends of the two connecting rods 434 are fixedly connected with the top ends of the U-shaped section of the second-stage pressure arm 431, and the top ends of the two connecting rods 434 are detachably connected with the gland 32;

The loader body 41 comprises a spiral loader 411, a loader bracket 412, a spring barrel 413 and a belleville spring 414, wherein the loader bracket 412 is a portal frame, the loader bracket 412 is vertically arranged above a bending section of the primary pressure arm 421, the bottom end of the loader bracket 412 is fixed on a table top of the machine base 1, a loader assembly through hole is machined on the loader bracket 412 and is coaxially arranged with a step hole of the primary pressure arm 421, the spiral loader 411 is arranged on the loader bracket 412, a loading head of the spiral loader 411 penetrates through the loader assembly through hole of the loader bracket 412, the spring barrel 413 is coaxially arranged in the step hole of the primary pressure arm 421, the belleville spring 414 is arranged in the spring barrel 413, and the bottom end of the belleville spring 414 is in contact with the inner end surface of the step hole of the primary pressure arm 421;

the top supporting component 44 is arranged below the straight rod section of the primary pressure arm 421, the bottom end of the top supporting component 44 is fixed on the table top of the machine base 1, the top end of the top supporting component 44 is contacted with the bottom end of the primary pressure arm 421, the top supporting component 45 is arranged below the straight line section of the secondary pressure arm 431, the bottom end of the top supporting component 45 is fixed on the table top of the machine base 1, and the top end of the top supporting component 45 is contacted with the bottom end of the secondary pressure arm 431.

Further, the tip support assembly 44 includes a support tip 441 and a tip support seat 442, wherein a conical surface is formed on the top end of the support tip 441, an external thread is formed on the bottom end of the support tip 441, a threaded hole matched with the bottom end of the support tip 441 is formed on the tip support seat 442, and the support tip 441 is in screw connection with the tip support seat 442;

the thimble supporting assembly 45 comprises a supporting thimble 451 and a thimble supporting seat 452, wherein a conical surface is processed at the top end of the supporting thimble 451, an external thread is processed at the bottom end of the supporting thimble 451, a threaded hole matched with the low end of the supporting thimble 451 is processed on the thimble supporting seat 452, and the supporting thimble 451 is in spiral connection with the thimble supporting seat 452.

Further, the fatigue life testing machine also comprises an oil conveying system, wherein the oil conveying system comprises an oil tank 100, an oil conveying assembly and an oil return assembly, and the oil tank 100 is arranged on a bottom cross beam of the machine base 1;

an oil drain pipeline is processed on the supporting seat 31, the oil drain pipeline is formed by sequentially connecting an upper horizontal oil way 311, a middle vertical oil way 312 and a lower horizontal oil way 313, the end part of the upper horizontal oil way 311 is communicated with a circular accommodating groove 314 of the supporting seat 31, the axis of the upper horizontal oil way 311 is positioned at the middle point of an upper loading ring 33 and a lower loading ring 34, the end part of the lower horizontal oil way 313 is communicated with a circular oil dropping through hole 315 of the supporting seat 31, and the axis of the lower horizontal oil way 313 is positioned below the magnetic gasket 8;

The oil delivery assembly comprises an oil delivery pipeline, a heater, a booster pump and an oil delivery fine filter, one end of the oil delivery pipeline is connected with an oil outlet of the oil tank 100, the other end of the oil delivery pipeline is positioned above the oil receiving disc 7 and fixed on the supporting seat 31 through a bracket, the end part of the oil delivery pipeline points to an oil storage tank 71 of the oil receiving disc 7, the heater, the booster pump and the oil delivery fine filter are sequentially arranged on the oil delivery pipeline from front to back, the oil outlet of the oil tank 100 is connected with an oil inlet of the heater through the oil delivery pipeline, the oil outlet of the heater is connected with an oil inlet of the booster pump through the oil delivery pipeline, the oil outlet of the booster pump is connected with an oil inlet of the oil delivery fine filter through the oil delivery pipeline, and the oil outlet of the oil delivery fine filter is connected to the oil storage tank 71 of the oil receiving disc 7 through the oil delivery pipeline;

the oil return assembly comprises an oil return pipeline, a magnetic filter, an oil return coarse filter, an oil return pump and an oil return fine filter, wherein an oil return pipe through hole is formed in the table top of the machine base 1, one end of the oil return pipeline penetrates through the oil return pipe through hole and is in sealing connection with an oil outlet at the bottom end of a circular oil falling through hole 315 of the supporting seat 31 through a quick connector, the other end of the oil return pipeline is connected with an oil return port of the oil tank 100, the magnetic filter, the oil return coarse filter, the oil return pump and the oil return fine filter are sequentially arranged on the oil return pipeline in front, at the middle and back, an oil outlet at the bottom end of the circular oil falling through hole 315 of the supporting seat 31 is connected with an oil inlet of the magnetic filter through the oil return pipeline, an oil outlet of the magnetic filter is connected with an oil inlet of the oil return coarse filter through the oil return pipeline, an oil outlet of the oil return coarse filter is connected with an oil inlet of the oil return pump through the oil return pipeline, and an oil inlet of the oil return fine filter is connected with an oil return port of the oil tank 100 through the oil return pipeline.

Further, the data acquisition system comprises a pressure sensor 200, a rotation speed sensor 201, an acceleration sensor 202 and three groups of temperature sensors,

the pressure sensor 200 is positioned between the belleville spring 414 and the spiral loader 411, the bottom end of the pressure sensor 200 is contacted with the top end of the belleville spring 414, the top end of the pressure sensor 200 is contacted with the loading head of the spiral loader 411, and the pressure sensor 200 is used for measuring the load of the spiral loader 411;

the rotating speed sensor 201 is positioned at the side of the electric spindle 51, a contact of the rotating speed sensor 201 points to a lock nut of the electric spindle 51, the rotating speed sensor 201 is arranged on a sensor support, the sensor support is arranged on a table top of the machine base 1, and the rotating speed sensor 201 is used for measuring the rotating speed of the test stick 6 in real time;

the acceleration sensor 202 is installed at the side edge of the gland 32, the acceleration sensor 202 is connected with the gland 32 in a magnetic attraction manner, and the acceleration sensor 202 is used for measuring test vibration frequency;

three sets of temperature sensors are respectively positioned on the inner wall of the oil tank 100, the inner wall of the free end of the oil delivery pipeline and the inner wall of the oil storage tank 71 of the oil receiving disc 7, and the three sets of temperature sensors are respectively used for measuring the temperature of the oil supply oil temperature and the test contact area of the lubricating oil.

Further, the fatigue life testing machine further comprises a ball contact tool, the ball contact tool comprises a ball socket shaft 300, a bearing ball 301 and a first screw 302, the top end of the ball socket shaft 300 is coaxially fixed on the electric spindle 51 through a collet chuck and a nut, a first threaded hole is formed in the center of the bottom end of the ball socket shaft 300, a spherical groove matched with the bearing ball 301 is formed in the lower end face of the ball socket shaft 300, a first screw assembly through hole is formed in the center of the bearing ball 301, and the bearing ball 301 is fastened on the ball socket shaft 300 through the first screw 302.

Further, the fatigue life testing machine further comprises a bearing inner ring contact tool, the bearing inner ring contact tool comprises a stepped shaft 400, a bearing inner ring 401, a shaft end retainer ring 402 and a second screw 403, the top end of the stepped shaft 400 is coaxially fixed on the electric main shaft 51 through a spring chuck and a nut, a second threaded hole is machined in the center of the bottom end of the stepped shaft 400, the bearing inner ring 401 is horizontally sleeved on the lower portion of the stepped shaft 400, and the bearing inner ring 401 is fastened on the stepped shaft 400 through the shaft end retainer ring 402 and the second screw 403.

Compared with the prior art, the invention has the following effects:

1. according to the invention, fatigue life test and process test are carried out on a single test bar 6, the matching and test of the test bar 6 and the accompanying test ball 37 with different sizes are realized by adopting the replaceable oil receiving disc 7, the rolling contact fatigue performance test requirements of different materials are met, the test bar 6 can carry out multi-station test, and the material cost is saved; adopting a replaceable tool to meet the rolling contact fatigue test and sliding friction wear test of the bearing inner ring, the roller, the ball and the like;

2. According to the invention, a lubrication mode of combining a semi-immersion oil type with an oil dripping type is adopted to obtain lubrication states such as elastohydrodynamic lubrication, mixed lubrication and boundary lubrication so as to simulate different lubrication working conditions, and an oil homogenizing groove is milled on the surface of the oil receiving disc 7, so that uniform oil supply in all directions is ensured;

3. the invention adopts a two-stage lever spring loading mode to realize stable elastic loading at high rotating speed, reduces loading force fluctuation caused by the influence of vibration and the like at high rotating speed, and saves space compared with the traditional lever loading;

4. the invention adopts the heating and control system of the lubricating oil heating and testing core device 3 to ensure that the temperature of the contact area can reach the required temperature environment and reduce the temperature fluctuation caused by normal-temperature lubricating oil.

5. The multifunctional rolling point contact fatigue life tester with variable working conditions can simulate the running state of the ball bearing under various working conditions, the maximum rotating speed of a driving motor can reach 18000r/min, and different lubrication states such as spring flow lubrication, mixed lubrication and boundary lubrication can be regulated and obtained by combining two modes of oil dripping and semi-oil immersion. The heating temperature of the test core device 3 can reach 300 ℃ at most, the oil supply temperature can reach 140 ℃, and the actual operation condition temperature can be simulated. The oil receiving disc 7 and the accompanying test ball 37 are designed to be replaceable, the size range of the accompanying test ball 37 is 6.35-12.7 mm, the size range of the test rod 6 is 9.525-30 mm, and the requirements of different material fatigue performance tests are met. Through changing the 3 frock of experimental core device, can satisfy the rolling contact fatigue test and the sliding friction wearing and tearing of multiple parts such as bearing roller, ball and inner circle.

Drawings

FIG. 1 is a schematic diagram of a variable operating mode multifunctional rolling point contact fatigue life tester of the present invention;

FIG. 2 is an enlarged view of a portion of FIG. 1 at Q;

FIG. 3 is a half cross-sectional view of the trial core assembly 3 of the present invention;

fig. 4 is a schematic structural view of the loading device 4 of the present invention;

FIG. 5 is a top view of the test stick 6 of the present invention assembled with the rolling contact assembly with the cage 36 removed;

FIG. 6 is a cross-sectional view at A-A of FIG. 5;

FIG. 7 is a cross-sectional view of the ball contact tooling of the present invention assembled with a rolling contact assembly;

FIG. 8 is a cross-sectional view of the bearing inner race contact tooling of the present invention assembled with a rolling contact assembly;

fig. 9 is a block diagram of the data acquisition system of the present invention.

Detailed Description

The first embodiment is as follows: referring to fig. 1 to 6, a multifunctional rolling point contact fatigue life tester with variable working conditions according to the present embodiment is described, wherein the fatigue life tester includes a base 1 and a lifting centering device 2, and the lifting centering device 2 is mounted on a table surface of the base 1; the fatigue life testing machine further comprises a testing core device 3, a loading device 4 and a driving device 5, wherein the driving device 5 is arranged on the lifting centering device 2, the test bar 6 is detachably arranged on the driving device 5, the test bar 6 is driven by the driving device 5 to realize rotary motion, the driving device 5 is driven by the lifting centering device 2 to realize longitudinal reciprocating motion and/or transverse reciprocating motion, and further the test bar 6 is driven to realize lifting motion and/or centering motion, the testing core device 3 is arranged on a table top of the machine base 1, and the testing core device 3 is positioned below the driving device 5; the test core device 3 comprises a supporting seat 31, a gland 32 and a rolling contact assembly, wherein the supporting seat 31 is of a round columnar structure, the supporting seat 31 is vertically arranged on a table top of the machine base 1, and a round accommodating groove 314 for accommodating the rolling contact assembly is formed in the center of the upper end face of the supporting seat 31; the rolling contact assembly comprises an upper loading ring 33, a lower loading ring 34, a gasket 35, a retainer 36 and test accompanying balls 37, wherein the upper loading ring 33, the lower loading ring 34 and the gasket 35 are sequentially and horizontally arranged in a circular accommodating groove 314 of a supporting seat 31 from top to bottom, the supporting seat 31 is in contact with the outer curved surfaces of the upper loading ring 33 and the lower loading ring 34, the gasket 35 is in contact with the inner end surface of the circular accommodating groove 314 of the supporting seat 31, the test accompanying balls 37 are symmetrically distributed around a test bar 6 in the center, the test bar 6 is in point contact with the test accompanying balls 37, the retainer 36 is horizontally arranged between the test bar 6 and the upper loading ring 33 and the lower loading ring 34, three pockets are uniformly formed in the retainer 36 along the circumferential direction, the test accompanying balls 37 are respectively arranged in the three pockets of the retainer 36, the inner side surfaces of the upper loading ring 33 and the lower loading ring 34, which are close to the test accompanying balls 37, the sloping surfaces of the upper loading ring 33 and the lower loading ring 34 are in point contact with the test accompanying balls 37, and gaps exist between the lower end surfaces of the upper loading ring 33 and the upper end surface of the lower loading ring 34; the gland 32 is horizontally arranged right above the supporting seat 31, the gland 32 is connected with the loading device 4, the lower end surface of the gland 32 is contacted with the upper end surface of the upper loading ring 33, and a moving gap exists between the lower end surface of the gland 32 and the upper end surface of the supporting seat 31; the loading device 4 is arranged on the table top of the machine base 1 and is connected with the gland 32 of the test core device 3, the loading device 4 applies load to the test core device 3, the load is applied to the upper loading ring 33 through the gland 32 and then is transferred to the accompanying test ball 37, and finally is transferred to the test rod 6, and the test rod 6 is coaxially and directly driven to rotate through the driving device 5, so that the three-point rolling contact test on the test rod 6 is realized.

The lifting centering device 2 of the embodiment comprises a sliding table body 21, a lifting screw mechanism 22 and a centering screw mechanism 23, wherein the sliding table body 21 is arranged on a table top of the machine base 1, the lifting screw mechanism 22 is vertically arranged on the front side of the sliding table body 21, the centering screw mechanism 23 is arranged on the front side of the lifting screw mechanism 22, the driving device 5 is arranged on the front side of the centering screw mechanism 23, the driving device 5 and the centering screw mechanism 23 are integrally driven by the lifting screw mechanism 22 to realize lifting movement, and the driving device 5 is driven by the centering screw mechanism 23 to realize centering movement;

the sliding table body 21 of the embodiment comprises a sliding table frame 211, a sliding table frame bottom plate 212, a sliding table frame cover plate 213 and a sliding table frame connecting plate 214, wherein the sliding table frame 211 is vertically arranged, the sliding table frame bottom plate 212 is fixedly arranged at the bottom end of the sliding table frame 211, the sliding table frame bottom plate 212 is fixedly connected with the machine base 1, the sliding table frame cover plate 213 is fixedly arranged at the top end of the sliding table frame 211, and the sliding table frame connecting plate 214 is fixedly arranged at the front end of the sliding table frame 211;

the driving device 5 of this embodiment includes an electric spindle 51, a split type mounting frame 52 and a plurality of connecting screws, the electric spindle 51 is vertically arranged above the test core device 3, an electric spindle assembly hole matched with the electric spindle 51 is processed on the split type mounting frame 52, the electric spindle 51 is inserted in the electric spindle assembly hole of the split type mounting frame 52, and the electric spindle 51 is locked on the split type mounting frame 52 through the plurality of connecting screws. The test bar 6 is coaxially and directly driven to rotate by the electric spindle 51.

The second embodiment is as follows: referring to fig. 1 and 3, the test core device 3 according to this embodiment further includes a disc-shaped oil receiving disc 7, the disc-shaped oil receiving disc 7 is horizontally disposed above the gland 32, the oil receiving disc 7 is connected with the gland 32 by a bolt, an oil storage tank 71 is machined in the center of the upper end surface of the oil receiving disc 7, a test rod assembly through hole 72 is machined in the center of the inner end surface of the oil storage tank 71, the aperture of the test rod assembly through hole 72 is 1-2 cm greater than the outer diameter of the test rod 6, an oil homogenizing groove is machined in the radial direction in the inner end surface of the oil storage tank 71, and an oil homogenizing groove is machined in the radial direction in the inner end surface of the oil storage tank 71. So set up, mill even oil groove at receiving oil pan 7 surface, guarantee the even oil feed of each direction. Other compositions and connection relationships are the same as those of the first embodiment.

And a third specific embodiment: referring to fig. 1 and 3, the test core device 3 of this embodiment further includes a magnetic gasket 8, a circular oil-dropping through hole 315 is machined in the center of an inner end surface of a circular receiving groove 314 of the supporting seat 31, an annular step is machined in the circumferential direction on an inner wall of an upper portion of the circular oil-dropping through hole 315, the magnetic gasket 8 is in an annular plate-shaped structure, the magnetic gasket 8 is horizontally disposed in the circular oil-dropping through hole 315, the magnetic gasket 8 is lapped on the annular step, and the magnetic gasket 8 is in contact with the inner end surface of the supporting seat 31. So set up, through the circular oil through hole 315 inside sealed installation magnetic gasket 8 at supporting seat 31 for form an oil storage space between magnetic gasket 8 and the supporting seat 31, in order to realize half immersion oil formula operating mode, magnetic gasket 8 can adsorb the iron fillings that experimental production in addition. Other compositions and connection relationships are the same as those of the first or second embodiment.

The specific embodiment IV is as follows: referring to fig. 1 and 3, the test core device 3 of the present embodiment further includes a heating collar 9 for heating the contact area, the heating collar 9 is sleeved outside the supporting seat 31 and is fixedly connected with the supporting seat 31, a first circular gland groove for clearance fit with the outer side surface of the heating collar 9 is machined on the lower end surface of the gland 32, and a second circular gland groove for clearance fit with the outer side surface of the upper loading ring 33 is machined on the inner end surface of the first circular gland groove. So set up, adopt heating lasso 9 to heat the test contact area, guarantee that the contact area temperature can reach required temperature environment, alleviate the temperature fluctuation that normal atmospheric temperature lubricating oil brought. Other compositions and connection relationships are the same as those of the first, second or third embodiments.

Fifth embodiment: the loading device 4 of the present embodiment includes a loader body 41, a pressure arm assembly i 42, a pressure arm assembly ii 43, a tip support assembly 44, and a tip support assembly 45, which are described with reference to fig. 1, 2, and 4;

So configured, the pressure sensor 200 is installed within the loader body 41 to ensure accuracy of pressure data required for the test and to monitor changes in the applied load during the test in real time. Other compositions and connection relationships are the same as those of the first, second, third or fourth embodiments.

The primary pressure arm 421 and the secondary pressure arm 431 of the present embodiment are respectively restrained by the primary pressure arm support 422 and the secondary pressure arm support 432, and constitute a secondary lever by the pressure lug 424.

The connecting rod 434 of the present embodiment is sleeved outside the supporting seat 31 in cooperation with the gland 32, and can move along the axial direction on the outer side surface of the supporting seat 31, so as to ensure that the loading force is vertically downward.

The screw loader 411 of the present embodiment measures pressure by the knob down pressure sensor 200 and compresses the belleville spring 414 by the pressure sensor 200 to apply a constant pressure vertically downward to the primary pressure arm 421, rotating the screw loader 411 knob to adjust the loading force.

Specific embodiment six: referring to fig. 1, 2 and 4, the tip support assembly 44 of the present embodiment includes a support tip 441 and a tip support seat 442, wherein a conical surface is formed on the top end of the support tip 441, an external thread is formed on the bottom end of the support tip 441, a threaded hole matching with the bottom end of the support tip 441 is formed on the tip support seat 442, and the support tip 441 is in screw connection with the tip support seat 442;

the thimble supporting assembly 45 comprises a supporting thimble 451 and a thimble supporting seat 452, wherein a conical surface is processed at the top end of the supporting thimble 451, an external thread is processed at the bottom end of the supporting thimble 451, a threaded hole matched with the low end of the supporting thimble 451 is processed on the thimble supporting seat 452, and the supporting thimble 451 is in spiral connection with the thimble supporting seat 452. The device is arranged in such a way to ensure that the primary pressure arm 421 and the secondary pressure arm 431 of the preloading link are horizontal, so that the gland 32 is ensured to apply a load vertically downwards, the screw loader 411 is ensured to apply accurate loading force on a test piece, and meanwhile, the center support assembly 44 is used for unloading the secondary pressure arm 431, so that the gland 32 is ensured to be conveniently disassembled. Other compositions and connection relationships are the same as those of the first, second, third, fourth or fifth embodiments.

Seventh embodiment: referring to fig. 1, the fatigue life testing machine of the present embodiment further includes an oil delivery system, where the oil delivery system includes an oil tank 100, an oil delivery assembly and an oil return assembly, and the oil tank 100 is mounted on a bottom beam of the stand 1;

The oil return assembly comprises an oil return pipeline, a magnetic filter, an oil return coarse filter, an oil return pump and an oil return fine filter, wherein an oil return pipe through hole is formed in the table top of the machine base 1, one end of the oil return pipeline penetrates through the oil return pipe through hole and is in sealing connection with an oil outlet at the bottom end of a circular oil falling through hole 315 of the supporting seat 31 through a quick connector, the other end of the oil return pipeline is connected with an oil return port of the oil tank 100, the magnetic filter, the oil return coarse filter, the oil return pump and the oil return fine filter are sequentially arranged on the oil return pipeline in front, at the middle and back, an oil outlet at the bottom end of the circular oil falling through hole 315 of the supporting seat 31 is connected with an oil inlet of the magnetic filter through the oil return pipeline, an oil outlet of the magnetic filter is connected with an oil inlet of the oil return coarse filter through the oil return pipeline, an oil outlet of the oil return coarse filter is connected with an oil inlet of the oil return pump through the oil return pipeline, and an oil inlet of the oil return fine filter is connected with an oil return port of the oil tank 100 through the oil return pipeline. So configured, the oil tank 100 is used for storing circulating oil, the booster pump and the scavenge pump are used for adjusting the lubricant delivery rate, and the heater is used for heating the lubricant. Other compositions and connection relationships are the same as those of the first, second, third, fourth, fifth or sixth embodiments.

The quick connector of the embodiment is a polyether-ether-ketone (PEEK) quick connector, on one hand, the polyether-ether-ketone (PEEK) quick connector can realize quick connection between an oil return pipeline and an oil outlet at the bottom end of the circular oil dropping through hole 315 of the supporting seat 31; on the other hand, the polyether-ether-ketone (PEEK) quick connector can also realize the effect of heat insulation, so that the heat loss of oil liquid is avoided.

Eighth embodiment: the data acquisition system of the present embodiment includes a pressure sensor 200, a rotation speed sensor 201, an acceleration sensor 202 and three sets of temperature sensors,

three sets of temperature sensors are respectively positioned on the inner wall of the oil tank 100, the inner wall of the free end of the oil delivery pipeline and the inner wall of the oil storage tank 71 of the oil receiving disc 7, and the three sets of temperature sensors are respectively used for measuring the temperature of the oil supply oil temperature and the test contact area of the lubricating oil. Other compositions and connection relationships are the same as those of the first, second, third, fourth, fifth, sixth or seventh embodiments.

The pressure sensor 200 of the present embodiment is installed between the screw loader 411 and the belleville spring 414 to ensure the accuracy of the loading force and monitor the load change in the test process in real time;

the rotation speed sensor 201 of the present embodiment is installed at the lock nut of the electric spindle 51 to measure the rotation speed of the test bar 6 in real time;

the temperature sensor of this embodiment is divided into two types, one temperature sensor measuring the temperature of the contact area and being installed between the gland 32 and the upper load ring 33 to indirectly measure the temperature of the contact area, and the other temperature sensor measuring the temperature of the oil supply and being installed at the oil supply port and the oil tank, respectively, to monitor the temperature of the oil supply in real time;

The acceleration sensor 202 of the present embodiment is installed on the side of the gland 32, and is used for measuring vibration signals in the test process, and the sensor is powered by a switching power supply, and transmits signals to a control computer through a collection card.

The system mainly determines failure through two signal indexes, namely a temperature signal, judges whether the fatigue testing machine works normally or not through monitoring the temperature of a contact area, and mainly reflects the lubrication condition of the pair of the rotating speed, the load and the friction of the test bar 6. Then, the vibration signal is acquired by the acceleration sensor 202 to determine whether a failure occurs in the contact area.

Detailed description nine: referring to fig. 7, the fatigue life testing machine according to the present embodiment further includes a ball contact fixture including a ball socket shaft 300, a bearing ball 301 and a first screw 302, wherein the top end of the ball socket shaft 300 is coaxially fixed to the electric spindle 51 through a collet chuck and a nut, a first screw hole is machined in the center of the bottom end of the ball socket shaft 300, a spherical groove for matching with the bearing ball 301 is machined in the lower end surface of the ball socket shaft 300, a first screw assembly through hole is machined in the center of the bearing ball 301, and the bearing ball 301 is fastened to the ball socket shaft 300 through the first screw 302. So arranged, the ball-and-socket shaft 300 drives the bearing ball 301 to coaxially rotate, and the bearing ball 301 is radially loaded by the three test balls 37, so that the rolling contact fatigue performance of the bearing ball 301 is tested. Other compositions and connection relationships are the same as those of the first, second, third, fourth, fifth, sixth, seventh or eighth embodiments. The test core device 3 of this embodiment adopts a replaceable test fixture to prove that the tester can meet specific test requirements of different parts by replacing the fixture.

Detailed description ten: referring to fig. 8, the fatigue life testing machine according to the present embodiment further includes a bearing inner ring contact fixture, where the bearing inner ring contact fixture includes a stepped shaft 400, a bearing inner ring 401, a shaft end retainer 402, and a second screw 403, the top end of the stepped shaft 400 is coaxially fixed on the electric spindle 51 through a collet chuck and a nut, a second threaded hole is machined in the center of the bottom end of the stepped shaft 400, the bearing inner ring 401 is horizontally sleeved on the lower portion of the stepped shaft 400, and the bearing inner ring 401 is fastened on the stepped shaft 400 through the shaft end retainer 402 and the second screw 403. So arranged, the stepped shaft 400 drives the bearing inner ring 401 to coaxially rotate, and the bearing inner ring 401 is radially loaded through the accompanying test balls 37, so that the rolling contact fatigue performance of the bearing inner ring is tested. Other compositions and connection relationships are the same as those of the one, two, three, four, five, six, seven, eight or nine embodiments.

Principle of operation

The working principle of the multifunctional rolling point contact fatigue life tester with variable working conditions is described with reference to fig. 1 to 8: firstly, the driving device 5 is moved to the uppermost position by the lifting centering device 2, the gasket 35 and the lower loading ring 34 are sequentially placed into the circular accommodating groove 314 of the supporting seat 31, the oil receiving disc 7 is mounted on the gland 32 by bolts, the collet chuck is mounted into the nut of the electric spindle 51, one end of the test bar 6 is inserted into the collet chuck, the retainer 36, the upper loading ring 33 and the gland 32 are sequentially mounted on the supporting seat 31, meanwhile, the test bar 6 is mounted on the driving device 5, centering is adjusted, radial runout is tested, and the nut is screwed. The driving device 5 is moved downwards to a proper position until the test ball 37 just contacts the test bar 6, the test ball 37 is put into the pocket hole of the retainer 36, and the gland 32 is connected with the two connecting rods 434 on the secondary pressure arm 431 through bolts and pre-tensioned. The acceleration sensor 202 is installed on the installation surface of the side face of the gland 32 by a double-end stud, a quick-plug connector of the temperature sensor is connected, and a lubricating oil outlet of an oil conveying pipeline is adjusted so that lubricating oil can drop onto the oil receiving disc 7. Checking the wiring of the control system, electrifying the control cabinet and the transformer, opening a switch of the control cabinet, and adjusting the rotating speed of the frequency converter to enable the rotating speed of the driving device 5 to reach a set value. The thimble supporting assembly 45 under the second-stage pressure arm 431 is removed, the screw loader 411 is adjusted to make the load reach a predetermined value, the liquid level and the pipeline of the oil conveying system are checked, the water cooling machine and the booster pump are turned on, lubricating oil is supplied to the contact area, and oil is continuously supplied for 10 minutes. And (3) opening a data acquisition system, checking whether a program works normally and stores data, closing an oil baffle to prevent oil splashing, and starting a test. After the test bar 6 is tired and stopped, the power supply of the control cabinet is required to be cut off, the acquisition procedure is stopped, and the water cooling machine is stopped after 5 minutes. When the next station test is performed on the test bar 6, the loading force is required to be unloaded, the accompanying test balls 37 are replaced, whether the upper loading ring 33 and the lower loading ring 34 are damaged or not is checked, the tool is recovered, and the driving device 5 is moved downwards to a required position by referring to the scale. The acceleration sensor 202 is disassembled, the quick-plugging port of the temperature sensor wire is disassembled, loading force is unloaded, the driving device 5 is moved to the uppermost position, the test bar 6 is convenient to disassemble, the tool is disassembled, the test bar 6 is packaged by a test piece box, the collet chuck and the nut are cleaned, the round accommodating groove 314 of the supporting seat 31, the gasket 35 and the gland 32 are cleaned, data are stored, and the power supply of the control cabinet is turned off.

The above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. The multifunctional rolling point contact fatigue life testing machine with the variable working conditions comprises a machine base (1) and a lifting centering device (2), wherein the lifting centering device (2) is arranged on a table top of the machine base (1); the fatigue life testing machine further comprises a testing core device (3), a loading device (4) and a driving device (5), wherein the driving device (5) is arranged on the lifting centering device (2), the test bar (6) is detachably arranged on the driving device (5), the test bar (6) is driven by the driving device (5) to realize rotary motion, the driving device (5) is driven by the lifting centering device (2) to realize longitudinal reciprocating motion and/or transverse reciprocating motion, the test bar (6) is driven to realize lifting motion and/or centering motion, the testing core device (3) is arranged on a table top of the machine base (1), and the testing core device (3) is positioned below the driving device (5); the test core device (3) comprises a supporting seat (31), a gland (32) and a rolling contact assembly, wherein the supporting seat (31) is of a round columnar structure, the supporting seat (31) is vertically arranged on a table top of the machine base (1), and a round accommodating groove (314) for accommodating the rolling contact assembly is formed in the center of the upper end face of the supporting seat (31); the rolling contact assembly comprises an upper loading ring (33), a lower loading ring (34), a gasket (35), a retainer (36) and test accompanying balls (37), wherein the upper loading ring (33), the lower loading ring (34) and the gasket (35) are sequentially and horizontally arranged in a circular accommodating groove (314) of a supporting seat (31) from top to bottom, the supporting seat (31) is contacted with the outer curved surfaces of the upper loading ring (33) and the lower loading ring (34), the gasket (35) is contacted with the inner end surfaces of the circular accommodating groove (314) of the supporting seat (31), the test accompanying balls (37) are symmetrically distributed around a test bar (6), the test bar (6) is in point contact with the test accompanying balls (37), the retainer (36) is horizontally arranged between the test bar (6) and the upper loading ring (33) and the lower loading ring (34), three pocket holes are uniformly processed on the retainer (36) along the circumferential direction, the test accompanying balls (37) are respectively arranged in the three holes of the retainer (36), the upper loading ring (33) and the lower loading ring (33) are close to the upper end surfaces of the test accompanying balls (34), and the upper end surfaces of the test accompanying balls (34) are in point contact with the test accompanying balls (37), and the upper end surfaces of the test balls (33) are in point contact with the test accompanying balls (37; the gland (32) is horizontally arranged right above the supporting seat (31), the gland (32) is connected with the loading device (4), the lower end face of the gland (32) is contacted with the upper end face of the upper loading ring (33), and a moving gap exists between the lower end face of the gland (32) and the upper end face of the supporting seat (31); the loading device (4) is arranged on the table top of the machine base (1) and is connected with a gland (32) of the test core device (3), the loading device (4) applies load to the test core device (3), the load is applied to an upper loading ring (33) through the gland (32) and then is transferred to a test ball (37) to be finally transferred to the test bar (6), and the test bar (6) is coaxially and directly driven to rotate through the driving device (5), so that a three-point rolling contact test on the test bar (6) is realized; the method is characterized in that: the fatigue life testing machine further comprises a ball contact tool, the ball contact tool comprises a ball socket shaft (300), a bearing ball (301) and a first screw (302), the top end of the ball socket shaft (300) is coaxially fixed on the electric spindle (51) through a spring chuck and a nut, a first threaded hole is formed in the center of the bottom end of the ball socket shaft (300), a spherical groove matched with the bearing ball (301) is formed in the lower end face of the ball socket shaft (300), a first screw assembly through hole is formed in the center of the bearing ball (301), and the bearing ball (301) is fastened on the ball socket shaft (300) through the first screw (302); the fatigue life testing machine further comprises a bearing inner ring contact tool, the bearing inner ring contact tool comprises a stepped shaft (400), a bearing inner ring (401), a shaft end check ring (402) and a second screw (403), the top end of the stepped shaft (400) is coaxially fixed on the electric spindle (51) through a collet chuck and a nut, a second threaded hole is machined in the center of the bottom end of the stepped shaft (400), the bearing inner ring (401) is horizontally sleeved on the lower portion of the stepped shaft (400), and the bearing inner ring (401) is fastened on the stepped shaft (400) through the shaft end check ring (402) and the second screw (403).

2. The variable duty multifunctional rolling point contact fatigue life tester according to claim 1, wherein: the test core device (3) further comprises an oil receiving disc (7), the oil receiving disc (7) is of a disc-shaped structure, the oil receiving disc (7) is horizontally arranged above the gland (32), the oil receiving disc (7) is connected with the gland (32) through bolts, an oil storage groove (71) is formed in the center of the upper end face of the oil receiving disc (7), a test rod assembly through hole (72) is formed in the center of the inner end face of the oil storage groove (71), the aperture of the test rod assembly through hole (72) is larger than the outer diameter of the test rod (6) by 1-2 cm, and an oil homogenizing groove is formed in the inner end face of the oil storage groove (71) in a radial machining mode.

3. The variable duty multifunctional rolling point contact fatigue life tester according to claim 1 or 2, wherein: the test core device (3) further comprises a magnetic gasket (8), a circular oil dropping through hole (315) is formed in the center of the inner end face of the circular accommodating groove (314) of the supporting seat (31), an annular step is formed in the inner wall of the upper portion of the circular oil dropping through hole (315) in a machining mode along the circumferential direction, the magnetic gasket (8) is of an annular plate-shaped structure, the magnetic gasket (8) is horizontally arranged in the circular oil dropping through hole (315), the magnetic gasket (8) is lapped on the annular step, and the magnetic gasket (8) is in contact with the inner end face of the supporting seat (31).

4. A variable duty multifunctional rolling point contact fatigue life tester according to claim 3, wherein: the test core device (3) further comprises a heating ferrule (9) used for heating the contact area, the heating ferrule (9) is sleeved outside the supporting seat (31) and fixedly connected with the supporting seat (31), a first round gland groove used for being in clearance fit with the outer side face of the heating ferrule (9) is processed on the lower end face of the gland (32), and a second round gland groove used for being in clearance fit with the outer side face of the upper loading ring (33) is processed on the inner end face of the first round gland groove.

5. The variable duty multifunctional rolling point contact fatigue life tester according to claim 1, 2 or 4, wherein: the loading device (4) comprises a loader body (41), a pressure arm assembly I (42), a pressure arm assembly II (43), a center support assembly (44) and a center support assembly (45);

the pressure arm assembly I (42) comprises a first-stage pressure arm (421), a first-stage pressure arm pin roll (423), a pressure lug (424), a shaft pin (425) and two first-stage pressure arm supports (422), wherein the first-stage pressure arm (421) comprises a bending section, a circular ring section and a straight rod section, the bending section, the circular ring section and the straight rod section are sequentially connected from front to back, the end parts of the straight rod sections of the first-stage pressure arm (421) are respectively and rotatably connected with the first-stage pressure arm supports (422) on two sides through the first-stage pressure arm pin roll (423), the bottom ends of the first-stage pressure arm supports (422) are fixedly arranged on the table top of the machine base (1), the top ends of the pressure lug (424) are rotatably connected with the middle parts of the straight rod sections of the first-stage pressure arm (421) through the shaft pin (425), and step holes are formed in the end parts of the bending sections of the first-stage pressure arm (421);

The pressure arm assembly II (43) comprises a second-stage pressure arm (431), two second-stage pressure arm supports (432), two second-stage pressure arm pins (433) and two connecting rods (434), the second-stage pressure arm (431) comprises a U-shaped section and a straight-line section, the middle of the U-shaped section is connected with the end of the straight-line section, two ends of the U-shaped section of the second-stage pressure arm (431) are respectively and rotatably connected with the second-stage pressure arm supports (432) on two sides through the second-stage pressure arm pins (433), the bottom ends of the second-stage pressure arm supports (432) are fixed on the table top of the machine base (1), the top ends of the straight-line section of the second-stage pressure arm (431) are contacted with the bottom ends of the pressure lugs (424), the two connecting rods (434) are respectively and vertically arranged on the front side and the rear side of the supporting base (31), the bottom ends of the two connecting rods (434) are fixedly connected with the top ends of the U-shaped section of the second-stage pressure arm (431), and the top ends of the two connecting rods (434) are detachably connected with the gland (32);

the loader body (41) comprises a spiral loader (411), a loader support (412), a spring barrel (413) and a belleville spring (414), wherein the loader support (412) is a portal frame, the loader support (412) is vertically arranged above a bending section of the primary pressure arm (421), the bottom end of the loader support (412) is fixed on a table top of the machine base (1), a loader assembly through hole is machined in the loader support (412), the loader assembly through hole is coaxially arranged with a step hole of the primary pressure arm (421), the spiral loader (411) is arranged on the loader support (412), a loading head of the spiral loader (411) penetrates through the loader assembly through hole of the loader support (412), the spring barrel (413) is coaxially arranged in a step hole of the primary pressure arm (421), the belleville spring (414) is arranged inside the spring barrel (413), and the bottom end of the belleville spring (414) is in surface contact with the step hole inner end of the primary pressure arm (421);

The top supporting component (44) is arranged below the straight rod section of the primary pressure arm (421), the bottom end of the top supporting component (44) is fixed on the table top of the machine base (1), the top end of the top supporting component (44) is in contact with the bottom end of the primary pressure arm (421), the top supporting component (45) is arranged below the straight line section of the secondary pressure arm (431), the bottom end of the top supporting component (45) is fixed on the table top of the machine base (1), and the top end of the top supporting component (45) is in contact with the bottom end of the secondary pressure arm (431).

6. The variable-operating-condition multifunctional rolling-point contact fatigue life testing machine according to claim 5, wherein: the center support assembly (44) comprises a support center (441) and a center support seat (442), wherein a conical surface is machined at the top end of the support center (441), an external thread is machined at the bottom end of the support center (441), a threaded hole matched with the bottom end of the support center (441) is machined in the center support seat (442), and the support center (441) is in spiral connection with the center support seat (442);

thimble supporting component (45) are including supporting thimble (451) and thimble supporting seat (452), and support thimble (451) top processing has the conical surface, and support thimble (451) bottom processing has the external screw thread, and processing has the screw hole with support thimble (451) low end assorted on thimble supporting seat (452), support thimble (451) and thimble supporting seat (452) screwed connection.

7. The variable duty multifunctional rolling point contact fatigue life tester according to claim 6, wherein: the fatigue life testing machine also comprises an oil conveying system, wherein the oil conveying system comprises an oil tank (100), an oil conveying assembly and an oil return assembly, and the oil tank (100) is arranged on a bottom cross beam of the machine base (1);

an oil drain pipeline is machined on the supporting seat (31), the oil drain pipeline is formed by sequentially connecting an upper horizontal oil way (311), a middle vertical oil way (312) and a lower horizontal oil way (313), the end part of the upper horizontal oil way (311) is communicated with a circular accommodating groove (314) of the supporting seat (31), the axis of the upper horizontal oil way (311) is positioned at the middle point of an upper loading ring (33) and a lower loading ring (34), the end part of the lower horizontal oil way (313) is communicated with a circular oil dropping through hole (315) of the supporting seat (31), and the axis of the lower horizontal oil way (313) is positioned below the magnetic gasket (8);

the oil delivery assembly comprises an oil delivery pipeline, a heater, a booster pump and an oil delivery fine filter, one end of the oil delivery pipeline is connected with an oil outlet of an oil tank (100), the other end of the oil delivery pipeline is positioned above an oil receiving disc (7) and fixed on a supporting seat (31) through a bracket, the end part of the oil delivery pipeline points to an oil storage tank (71) of the oil receiving disc (7), the heater, the booster pump and the oil delivery fine filter are sequentially arranged on the oil delivery pipeline from front to back, the oil outlet of the oil tank (100) is connected with an oil inlet of the heater through the oil delivery pipeline, the oil outlet of the heater is connected with an oil inlet of the booster pump through the oil delivery pipeline, the oil outlet of the booster pump is connected with an oil inlet of the oil delivery fine filter through the oil delivery pipeline, and the oil outlet of the oil delivery fine filter is connected to the oil storage tank (71) of the oil receiving disc (7);

The oil return assembly comprises an oil return pipeline, a magnetic filter, an oil return coarse filter, an oil return pump and an oil return fine filter, wherein an oil return pipe through hole is formed in the table top of the base (1), one end of the oil return pipeline penetrates through the oil return pipe through hole and is in sealing connection with an oil outlet at the bottom end of a circular oil falling through hole (315) of the supporting seat (31) through a quick connector, the other end of the oil return pipeline is connected with an oil return port of the oil tank (100), the magnetic filter, the oil return coarse filter, the oil return pump and the oil return fine filter are sequentially arranged on the oil return pipeline in front, at the middle and back, an oil outlet at the bottom end of the circular oil falling through hole (315) of the supporting seat (31) is connected with an oil inlet of the magnetic filter through the oil return pipeline, an oil outlet of the magnetic filter is connected with an oil inlet of the oil return coarse filter through the oil return pipeline, an oil outlet of the oil return coarse filter is connected with an oil inlet of the oil return pump through the oil return pipeline, and an oil outlet of the oil return fine filter is connected with an oil inlet of the oil return fine filter through the oil return pipeline, and an oil inlet and an oil outlet of the oil return fine filter is connected with an oil return port of the oil tank (100).

8. The variable duty multifunctional rolling point contact fatigue life tester according to claim 7, wherein: the data acquisition system comprises a pressure sensor (200), a rotating speed sensor (201), an acceleration sensor (202) and three groups of temperature sensors,

The pressure sensor (200) is positioned between the belleville spring (414) and the spiral loader (411), the bottom end of the pressure sensor (200) is contacted with the top end of the belleville spring (414), the top end of the pressure sensor (200) is contacted with the loading head of the spiral loader (411), and the pressure sensor (200) is used for measuring the load of the spiral loader (411);

the rotating speed sensor (201) is positioned at the side of the electric spindle (51), a contact of the rotating speed sensor (201) points to a lock nut of the electric spindle (51), the rotating speed sensor (201) is arranged on a sensor support, the sensor support is arranged on a table top of the machine base (1), and the rotating speed sensor (201) is used for measuring the rotating speed of the test bar (6) in real time;

the acceleration sensor (202) is arranged on the side edge of the gland (32), the acceleration sensor (202) is connected with the gland (32) in a magnetic attraction mode, and the acceleration sensor (202) is used for measuring test vibration frequency;

the three groups of temperature sensors are respectively positioned on the inner wall of the oil tank (100), the inner wall of the free end of the oil delivery pipeline and the inner wall of the oil storage tank (71) of the oil receiving disc (7), and are respectively used for measuring the temperature of the oil supply and oil temperature test contact area of lubricating oil.