Rolling bearing contact area lubrication state monitoring device and method

Abstract

The invention belongs to the technical field of monitoring equipment, and particularly relates to a device and method for monitoring the lubrication state of a rolling bearing contact area. The insulation assembly comprises a shaft sleeve and a base, the shaft sleeve and the base are both made of insulation materials, the bearing installation shaft is sleeved with the shaft sleeve, a shaft ring of the thrust ball bearing is fixed to the shaft sleeve through a metal bearing gasket in a sleeving mode, and the upper side of the base is fixed to a seat ring of the thrust ball bearing; the conductive assembly comprises a conductive contact and a conductive ball plug and is used for being electrically connected with the thrust ball bearing, the metal bearing washer and an external voltage source to form an electrified loop, and the voltage source is used for providing constant voltage for the thrust ball bearing; the driving unit is used for driving the thrust ball bearing to rotate; the loading unit is used for providing axial loading force for the thrust ball bearing; and the processing unit is used for acquiring the current of the electrified loop in real time and determining the minimum oil film thickness in the thrust ball bearing through the constant voltage provided by the voltage source so as to judge the lubrication state of the thrust ball bearing.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of monitoring equipment, and particularly relates to a rolling bearing contact area lubrication state monitoring device and method. BACKGROUND

[0002] The lubrication state of a rolling bearing is in a state of change at any time during operation. At present, the development of industry takes improving bearing life as an important development means, and the bearing life is also a key point of research at the present stage. Real-time observation of the lubrication state of the bearing contact area is an important means and method for improving the bearing life.

[0003] The rolling bearing is mainly a thrust ball bearing. The thrust ball bearing comprises a shaft ring, a seat ring and a steel ball and a retainer arranged between the shaft ring and the seat ring, and the steel ball and the retainer are integrally arranged. The thrust ball bearing plays a vital role in various mechanical equipment, especially in harsh working conditions such as high load and high speed. The lubrication state is a key factor affecting the performance and service life of the thrust ball bearing. If the lubrication state of the thrust ball bearing can be obtained in time, the wear condition of the bearing contact area can be improved by changing the operating conditions of the thrust ball bearing such as speed and stress, so as to greatly reduce the equipment failure rate and avoid major equipment accidents.

[0004] In the process of analyzing the correlation mechanism between the change of the lubrication state caused by the contact of the thrust ball bearing contact area components and the change of the overall electric field of the bearing, and the process of making corresponding changes to the operating conditions of the thrust ball bearing to improve the wear condition of the thrust ball bearing and improve the service life and reliability of the bearing, it is found that the change of the lubrication state of the thrust ball bearing contact area is a difficult state to capture. Although the traditional lubrication monitoring methods such as optical method and acoustic method can provide relevant lubrication information to a certain extent, there are problems such as slow response speed and low monitoring accuracy, and it is difficult to obtain high-precision data, thereby affecting the accurate judgment of whether serious friction damage occurs to the thrust ball bearing in engineering practice. Therefore, a rolling bearing contact area lubrication state monitoring device and method are urgently needed. SUMMARY

[0005] In order to solve the problems existing in the prior art, the purpose of the present application is to provide a rolling bearing contact area lubrication state monitoring device and method, which can accurately obtain the real-time lubrication state of the thrust ball bearing contact area, and provide accurate and reliable judgment basis for the friction damage of the thrust ball bearing in engineering practice.

[0006] The technical scheme of the present application is: A rolling bearing contact area lubrication state monitoring device and method for monitoring the lubrication state of a thrust ball bearing, the monitoring device comprising: a bearing mounting shaft; An insulating assembly, comprising a shaft sleeve and a base, both of which are made of insulating material, the shaft sleeve is sleeved on the bearing mounting shaft, the shaft ring of the thrust ball bearing is sleeved and fixed on the shaft sleeve through a metal bearing washer, the upper side of the base is fixed with the seat ring of the thrust ball bearing, and the shaft sleeve and the base are used to insulate the thrust ball bearing; A conductive assembly, comprising a conductive contact and a conductive ball plug, which are used to form a current loop in electrical connection with the thrust ball bearing, the metal bearing washer and an external voltage source, and the voltage source is used to provide a constant voltage for the thrust ball bearing; A driving unit, the output end of which is connected with the bearing mounting shaft, and is used to drive the thrust ball bearing to rotate; A loading unit, the output end of which is connected with the base, and is used to provide an axial loading force for the thrust ball bearing; A processing unit, comprising a collection module and a processing module, the collection module is used to acquire the current of the current loop in real time, and the processing module is used to determine the minimum oil film thickness in the thrust ball bearing through the constant voltage provided by the voltage source and the acquired current in real time, so as to judge the lubrication state of the thrust ball bearing.

[0007] Preferably, the thrust ball bearing is further provided with an oil injection unit on one side, which is used to provide different lubrication states for the thrust ball bearing, the oil injection unit comprises an oil tank, an oil pump, an oil conveying pipe and oil injection nozzles, the oil inlet of the oil pump is communicated with the oil tank, the oil outlet is communicated with one end of the oil conveying pipe, the oil injection nozzles are arranged in a circumferential array on the side of the thrust ball bearing, and the other end of the oil conveying pipe is connected with the oil injection nozzles through a flow divider.

[0008] Preferably, the driving unit comprises: A driving spindle, which is coaxial with the bearing mounting shaft, and is connected with the bearing mounting shaft through a stabilizing assembly; A driving motor, the output shaft of which is coaxially fixed with the driving spindle; A bearing mounting shaft, the upper end of which is connected with the driving spindle through the stabilizing assembly, and the lower end of which is sleeved and fixed in the shaft sleeve; The stabilizing assembly comprises a shell, a mandrel and single-row angular contact ball bearings, the shell is used to be fixed on a rack, the mandrel is coaxially arranged on the shell and is inserted through the shell, the upper end of the mandrel is fixedly connected with the driving spindle, and the lower end of the mandrel is fixedly connected with the bearing mounting shaft, one single-row angular contact ball bearing is arranged between the upper end of the mandrel and the inner side wall of the shell, and two single-row angular contact ball bearings are arranged between the lower end of the mandrel and the inner wall of the shell.

[0009] Preferably, a torque sensor is connected to the driving spindle, and a detection end of the torque sensor is connected to the driving spindle, for monitoring the torque generated by the thrust ball bearing during operation.

[0010] Preferably, the loading unit comprises: a support shaft parallel to the bearing mounting shaft, and an upper end of the support shaft is fixed to the base; a loading spring, and an upper end of the loading spring is fixed to the support shaft; a lifting plate fixed to a lower end of the loading spring; a lifting assembly, and an output end of the lifting assembly is connected to the lifting plate, for driving the lifting plate to move up and down in a vertical direction to compress the loading spring, so as to load the thrust ball bearing with an axial force.

[0011] Preferably, a load cell is mounted between the loading spring and the support shaft, for monitoring the axial force loaded on the thrust ball bearing by the loading spring.

[0012] Preferably, the lifting assembly comprises: a rotary driver; a lead screw vertically arranged, and an upper end of the lead screw is inserted through the lifting plate, and a lead screw nut is sleeved on the lead screw, the lead screw nut is fixed to the lifting plate, the loading spring is sleeved on the upper end of the lead screw, and a lower end of the loading spring is fixed to an output shaft of the rotary driver; two light rods parallel to and symmetrically arranged on both sides of the lead screw, and support plates are fixed to upper and lower ends of the light rods respectively, and the support plate on the lower side is fixed to a housing of the rotary driver, the lifting plate is sleeved on the two light rods respectively, and the lifting plate is in sliding connection with the light rods.

[0013] Preferably, a monitoring method of a rolling bearing contact area lubrication state monitoring device comprises the following steps: an axial force is applied to the thrust ball bearing to drive the thrust ball bearing to rotate; when the thrust ball bearing moves to a stable state, a constant voltage is applied to a power supply circuit composed of the thrust ball bearing, the conductive ball plug and the metal bearing washer by a voltage source, and real-time current in the power supply circuit is collected by a collection module and transmitted to a processing module, the processing module acquires a current change peak value in the received current, and when the current change peak value reaches a set proportion, the minimum oil film thickness in the thrust ball bearing is determined according to the acquired current peak value and the constant voltage provided by the voltage source, so as to determine the lubrication state of the thrust ball bearing.

[0014] Preferably, the minimum oil film thickness in the thrust ball bearing is determined according to the following formula: , Wherein, , In the formula, h is the oil film thickness, μm; U is the measured voltage drop of the contact area, V; U IR , R is the measured contact resistance of the contact area of the thrust ball bearing, I is the measured current of the contact area of the thrust ball bearing, A; R 0 is the reference resistance, h 0 is the characteristic thickness parameter of the contact area of the thrust ball bearing, μm; k 1 is the correction coefficient of the surface roughness of the contact area of the thrust ball bearing; k 2 is the correction coefficient of the temperature influence on the contact area of the thrust ball bearing; k 3 is the correction coefficient of the load effect on the contact area of the thrust ball bearing; k 4 is the correction coefficient of the rotational speed shear on the contact area of the thrust ball bearing; is the surface roughness of the contact area of the thrust ball bearing, is the empirical coefficient, and is between 0.5 and 1.0; T is the measured temperature of the contact area of the thrust ball bearing, T 0 is the reference temperature of the contact area of the thrust ball bearing, is the temperature coefficient, and is between 0.02 and 0.05; is the axial load of the contact area of the thrust ball bearing, is the reference load of the contact area of the thrust ball bearing; is the load coefficient, and is between 0.1 and 0.3; n is the rotational speed of the thrust ball bearing; n 0 is the reference rotational speed of the thrust ball bearing; is the rotational speed coefficient, and is between 0.05 and 0.1.

[0015] Compared with the prior art, the rolling bearing contact area lubrication state monitoring device and method has the following beneficial effects: ​The application adopts a driving unit and a loading unit, so that the race, steel ball and shaft ring of the thrust ball bearing are contacted and loaded with a certain axial force through the rotation of the driving spindle, thereby simulating the working state of the thrust ball bearing, and then when the thrust ball bearing moves to a stable state, a constant voltage is applied to the power supply loop composed of the conductive ball plug, metal bearing washer and conductive contact, and at the same time, the real-time current in the power supply loop is collected by the collection module and transmitted to the processing module, the processing module obtains the change peak value of the current, and when the change peak value of the current reaches a set proportion, the minimum oil film thickness in the thrust ball bearing is calculated according to the obtained current peak value, so as to judge the lubrication state of the thrust ball bearing, so that the lubrication state change of the overall contact area of the bearing under the actual working condition can be monitored in real time, and efficient monitoring of the microscopic contact area can be realized, which is beneficial to timely discovering and processing the bearing lubrication failure and collision wear, and provides accurate and reliable judgment basis for the friction damage of the thrust ball bearing in engineering practice. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall structure in the embodiment of the application; Figure 2 It is a schematic diagram of the structure of the bearing connecting unit in the embodiment of the application; Figure 3 It is a schematic diagram of the local structure of the bearing connecting unit in the embodiment of the application; Figure 4 It is a schematic diagram of the structure of the loading unit in the embodiment of the application.

[0017] BRIEF DESCRIPTION OF DRAWINGS: 1, driving motor; 2, driving spindle; 3, torque sensor; 4, shell; 5, bearing mounting shaft; 6, support shaft; 7, loading spring; 8, lifting plate; 9, light lever; 10, support plate; 11, rotary driver; 12, single-row angular contact ball bearing; 13, shaft sleeve; 14, thrust ball bearing; 15, base; 16, conductive contact; 17, metal bearing washer; 18, conductive ball plug; 19, mounting seat; 20, weighing sensor; 21, lead screw; 22, bearing seat; 23, oil nozzle; 24, bearing cavity. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical scheme and advantages of the application more clear and understandable, the application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the application and not to limit the application.

[0019] Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0020] In addition, the technical solutions among various embodiments of the present application can be combined with each other, but the combination of the technical solutions should be considered not to exist and not within the protection scope of the present application on the basis that the combination of the technical solutions can be realized by the ordinary skilled in the art, and the combination of the technical solutions cannot be realized.

[0021] Referring to Figures 1 to 4 As shown, in order to accurately obtain the real-time lubrication state of the contact area of the thrust ball bearing 14, and to provide accurate and reliable judgment basis for the friction damage of the thrust ball bearing 14 in engineering practice, the embodiment provides a rolling bearing contact area lubrication state monitoring device and method for monitoring the lubrication state of the thrust ball bearing 14. The monitoring device comprises a rack, a bearing mounting shaft 5, an insulating assembly, a conductive assembly, a driving unit, a loading unit and a processing unit.

[0022] The thrust ball bearing 14 comprises a shaft ring, a seat ring, a steel ball and a retaining ring for positioning the steel ball assembly. The steel ball assembly and the retaining ring are integrally arranged, and the shaft ring and the seat ring are located on the upper and lower sides of the steel ball assembly and are designed separately.

[0023] The insulating assembly comprises a shaft sleeve 13 and a base 15, both of which are made of insulating materials. The shaft sleeve 13 is sleeved on the bearing mounting shaft 5, and the shaft ring of the thrust ball bearing 14 is sleeved and fixed on the bearing mounting shaft 5 through a metal bearing washer 17. During installation, the metal bearing washer 17 is insulated and isolated from the bearing mounting shaft 5. The upper side of the base 15 is fixed with the seat ring of the thrust ball bearing 14, and the lower side is fixed on the bearing seat 22. The bearing seat 22 is installed on the bearing cavity 24, and the bearing seat 22 is provided with a mounting seat 19 inside, which is fixed with the bearing cavity 24. Thus, the installation of the thrust ball bearing 14 through the shaft sleeve 13 and the base 15 realizes insulation and isolation to reduce the influence of external metal conductive components on the monitoring data during the monitoring process.

[0024] The conductive assembly comprises a conductive contact 16 and a conductive ball plug 18. The conductive contact 16 is arranged outside the thrust ball bearing 14, and the conductive ball plug 18 is connected to the lower side of the base 15. The conductive contact 16, the conductive ball plug 18, the thrust ball bearing 14, the metal bearing washer 17 and the external voltage source are electrically connected to form a power supply loop, and the voltage source can provide a constant voltage for the thrust ball bearing 14 during the monitoring process. The driving unit is mounted on the rack and mainly comprises a driving motor 1, a driving main shaft 2 and a stabilizing assembly. The driving motor 1 is fixed to the rack and located at the top of the rack. The output shaft of the driving motor 1 is coaxially fixed to the vertically arranged driving main shaft 2. The lower end of the driving main shaft 2 is fixed to the bearing mounting shaft 5 through the stabilizing assembly. The bearing mounting shaft 5 is coaxially arranged with the driving main shaft 2. The lower end of the bearing mounting shaft 5 is fixedly sleeved in the shaft sleeve 13. The stabilizing assembly is composed of a shell 4, a mandrel and single-row angular contact ball bearings 12. Specifically, the shell 4 is fixed to the rack. The mandrel is coaxially arranged with the driving main shaft 2 and penetrates through the shell 4. The upper end of the mandrel is fixedly connected to the driving main shaft 2. The lower end of the mandrel is fixedly connected to the bearing mounting shaft 5. The upper end of the mandrel is connected to the inner side wall of the shell 4 through a single-row angular contact ball bearing 12. The lower end of the mandrel is connected to the inner wall of the shell 4 through two single-row angular contact ball bearings 12. Thus, the stabilizing assembly can effectively prevent the driving main shaft 2 and the bearing mounting shaft 5 from shaking during transmission. In use, the driving main shaft 2 and the bearing mounting shaft 5 are integrally designed through the connection of the stabilizing assembly. The driving motor 1 provides power for the driving main shaft 2 and the bearing mounting shaft 5 to realize the integrated rotary motion of the driving main shaft 2 and the bearing mounting shaft 5.

[0025] The loading unit is arranged at the bottom of the rack. The output end of the loading unit is fixedly connected to the bearing cavity 24 and used to drive the bearing cavity 24 to move up and down in the vertical direction, so as to realize the contact and separation between the raceway, the shaft ring and the steel balls of the thrust ball bearing 14.

[0026] Referring to Figure 1 As shown in the figure, the torque sensor 3 is arranged between the driving main shaft 2 and the rack. The detection end of the torque sensor 3 is connected to the driving main shaft 2 and used to monitor the torque generated during the operation of the thrust ball bearing 14.

[0027] Referring to Figure 1 As shown in the figure, the oil injection unit comprises an oil tank, an oil pump, an oil conveying pipe and a plurality of oil injection nozzles 23. The oil inlet of the oil pump is in communication with the oil tank. The oil outlet of the oil pump is in communication with one end of the oil conveying pipe. The plurality of oil injection nozzles 23 are circumferentially arranged at the side of the thrust ball bearing 14. The other end of the oil conveying pipe is connected to the plurality of oil injection nozzles 23 through a flow divider. The end of the oil conveying pipe close to the oil injection nozzles 23 is fixed to the rack to keep the position of the oil injection nozzles 23 stable. In order to ensure the uniformity of oil injection, it is appropriate to arrange three oil injection nozzles 23 circumferentially arranged at the side of the thrust ball bearing 14 to facilitate the improvement of the lubrication state and provide guidance for subsequent production and application.

[0028] Referring to Figure 1As shown, in order to better simulate the actual working condition of the thrust ball bearing 14, the monitoring data of the lubrication state of the contact area provides a reliable reference value. The loading unit includes a support shaft 6, a loading spring 7, a lifting plate 8 and a lifting assembly. The lifting assembly is composed of a rotary driver 11, a lead screw 21 and two light rods 9. The support shaft 6 is parallel to the bearing mounting shaft 5, and the upper end is fixed to the bearing cavity 24. The upper end of the loading spring 7 is fixed to the support shaft 6, and the lower end is fixed to the lifting plate 8. The lead screw 21 is vertically arranged, the upper end is inserted into the lifting plate 8, and the lower end is fixed to the output shaft of the rotary driver 11. The rotary driver 11 adopts a servo motor. The lead screw 21 is sleeved with a lead screw nut, the lead screw nut is fixed to the lifting plate 8, and the loading spring 7 is sleeved on the upper end of the lead screw 21. The two light rods 9 are parallel and symmetrically arranged on both sides of the lead screw 21, and the upper and lower ends of the light rod 9 are respectively fixed with a support plate 10, and the lower support plate 10 is fixed with the shell of the rotary driver 11 and the rack. The lifting plate 8 is sleeved on the two light rods 9, and the lifting plate 8 is slidably connected with the light rods 9. Thus, in use, the lifting plate 8 is driven by the lifting assembly to move up and down in the vertical direction to compress the loading spring 7, so as to realize the contact of the raceway, the steel ball and the shaft ring of the thrust ball bearing 14.

[0029] Referring to Figure 1 As shown, a weighing sensor 20 is installed between the loading spring 7 and the support shaft 6, which is a spoke type weighing sensor 20. It is used to monitor the size of the axial force of the loading spring 7 on the thrust ball bearing 14.

[0030] According to the rolling bearing contact area lubrication state monitoring device and the monitoring method thereof, the rolling bearing contact area lubrication state monitoring device comprises the following steps: Firstly, the oil injection unit is used to provide lubricating oil to the lubrication area of the thrust ball bearing 14 according to the experimental requirements, so as to simulate the initial lubrication state of the thrust ball bearing 14. In practice, the thrust ball bearing 14 can be simulated in multiple lubrication states according to different experimental requirements.

[0031] Further, the loading unit drives the bearing cavity 24 to move the base 15 upward along the vertical direction, so that the raceway, the steel ball and the shaft ring of the thrust ball bearing 14 are sequentially contacted, and the driving spindle 2 drives the thrust ball bearing 14 to provide axial force loading.

[0032] The driving unit is started to rotate the driving spindle 2, and the driving spindle 2 drives the thrust ball bearing 14 to rotate at a certain speed; When the thrust ball bearing 14 moves to a steady state, a constant voltage is applied to the power supply circuit composed of the conductive ball plug 18, the metal bearing washer 17 and the conductive contact 16, and at the same time, the real-time current in the power supply circuit is collected by the acquisition module and transmitted to the processing module. The processing module obtains the change peak value of the current from the received current, and when the change peak value of the current reaches a set proportion, the minimum oil film thickness in the thrust ball bearing 14 is calculated by the obtained current peak value, so as to judge the lubrication state of the thrust ball bearing 14.

[0033] Specifically, the minimum oil film thickness in the thrust ball bearing 14 is determined according to the following formula: , Among them R is the measured contact resistance (Ω), R 0 is the reference resistance (Ω) (related to the contact material and surface treatment), h is the oil film thickness (μm). h 0 is the characteristic thickness parameter (μm) (related to the viscosity of the lubricating oil and the surface roughness)

[0034] The above formula is moved and replaced by Ohm's law U = IR , after replacing the resistance, the following formula can be obtained Among them U is the measured voltage drop in the contact area (V), I is the measured current in the contact area (A) Since some experimental conditions during the experiment will have some influence on the results, the following correction coefficient is added on the basis of the above formula: Since the surface micro convex peak will pierce the oil film, resulting in an increase in the actual contact area and a decrease in the resistance, the surface roughness correction coefficient is added k 1; Since the increase of oil temperature will cause the viscosity of lubricating oil to decrease, the oil film to thin, and the resistance to decrease, the temperature influence correction coefficient is added k 2; Since the axial load will change the pressure distribution in the contact area, thereby affecting the oil film extrusion thickness, the load effect correction coefficient is added k 3; Since the increase of the rotating speed will enhance the dynamic pressure effect of the lubricating oil, so as to increase the oil film thickness and increase the resistance, the rotating speed shear correction coefficient is added k 4.

[0035] After introducing the correction coefficient, the calculation formula of the oil film thickness is corrected as follows: In the formula, h is the oil film thickness, μm;U V is the measured voltage drop for the contact zone; U IR , R R is the measured contact resistance for the contact zone of the thrust ball bearing; I I is the measured current for the contact zone of the thrust ball bearing, A; R 0 R is the reference resistance; h 0 H is the characteristic thickness parameter for the contact zone of the thrust ball bearing, pm; k 1 is the correction coefficient for the surface roughness of the contact zone of the thrust ball bearing; k 2 is the correction coefficient for the temperature effect on the contact zone of the thrust ball bearing; k 3 is the correction coefficient for the load effect on the contact zone of the thrust ball bearing; k 4 is the correction coefficient for the rotational speed shear on the contact zone of the thrust ball bearing; R is the surface roughness of the contact zone of the thrust ball bearing, K is the empirical coefficient, which is between 0.5 and 1.0; T T is the measured temperature for the contact zone of the thrust ball bearing, T T0 is the reference temperature for the contact zone of the thrust ball bearing, K is the temperature coefficient, which is between 0.02 and 0.05; F is the axial load for the contact zone of the thrust ball bearing, F0 is the reference load for the contact zone of the thrust ball bearing; K is the load coefficient, which is between 0.1 and 0.3; n N is the rotational speed of the thrust ball bearing; n N0 is the reference rotational speed of the thrust ball bearing; K is the rotational speed coefficient, which is between 0.05 and 0.1.

[0036] Therefore, by the above method, the lubrication state change of the overall contact zone of the bearing under actual working conditions can be monitored in real time, and efficient monitoring of the microscopic contact zone can be achieved, which is conducive to timely discovery and handling of bearing lubrication failure and collision wear, and provides accurate and reliable judgment basis for friction damage of the thrust ball bearing 14 in engineering practice.

[0037] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application also intends to include these modifications and variations.​

Claims

1. A rolling bearing contact zone lubrication state monitoring device for monitoring the lubrication state of a thrust ball bearing (14), characterized in that The monitoring device comprises: a bearing mounting shaft (5); an insulation assembly comprising a shaft sleeve (13) and a base (15), both made of insulating material, the shaft sleeve (13) being sleeved on the bearing mounting shaft (5), the shaft ring of the thrust ball bearing (14) being sleeved and fixed on the shaft sleeve (13) through a metal bearing washer (17), the base (15) being fixed with the seat ring of the thrust ball bearing (14) on the upper side, the shaft sleeve (13) and the base (15) being used to insulate the thrust ball bearing (14); a conductive assembly comprising a conductive contact (16) and a conductive ball plug (18) for electrically connecting the thrust ball bearing (14), the metal bearing washer (17) and an external voltage source to form an electric circuit, the voltage source being used to provide a constant voltage for the thrust ball bearing (14); a driving unit, the output end of which is connected with the bearing mounting shaft (5) for driving the thrust ball bearing (14) to rotate; a loading unit, the output end of which is connected with the base (15) for providing an axial loading force for the thrust ball bearing (14); a processing unit comprising a collection module and a processing module, the collection module being used to acquire the current of the electric circuit in real time, and the processing module being used to determine the minimum oil film thickness in the thrust ball bearing (14) through the constant voltage provided by the voltage source and the acquired current in real time, so as to judge the lubrication state of the thrust ball bearing (14).

2. A rolling bearing contact zone lubrication state monitoring device according to claim 1, characterized in that, The thrust ball bearing (14) is further provided with an oil injection unit on one side for providing different lubrication states for the thrust ball bearing (14), the oil injection unit comprising an oil storage tank, an oil pump, an oil delivery pipe and a plurality of oil injection nozzles (23), the oil inlet of the oil pump being communicated with the oil storage tank, the oil outlet being communicated with one end of the oil delivery pipe, the oil injection nozzles (23) being arranged in a circumferential array on the side of the thrust ball bearing (14), and the other end of the oil delivery pipe being connected with the oil injection nozzles (23) through a flow divider.

3. A device for monitoring the lubrication condition of a rolling bearing contact zone according to claim 1, characterized in that, The driving unit comprises: a driving spindle (2) coaxial with the bearing mounting shaft (5), the driving spindle (2) being connected with the bearing mounting shaft (5) through a stabilizing assembly; a driving motor (1), the output shaft of which is coaxially fixed with the driving spindle (2); the stabilizing assembly comprising a housing (4), a mandrel and single-row angular contact ball bearings (12), the housing (4) being used to be fixed on a rack, the mandrel being coaxially arranged with the driving spindle (2) and being inserted through the housing (4), the upper end of the mandrel being fixed with the driving spindle (2), and the lower end being fixed with the bearing mounting shaft (5), the upper end of the mandrel being connected with the inner wall of the housing (4) through one single-row angular contact ball bearing (12), and the lower end being connected with the inner wall of the housing (4) through two single-row angular contact ball bearings (12).

4. A rolling bearing contact zone lubrication state monitoring device according to claim 3, characterized in that, The driving main shaft (2) is connected with a torque sensor (3), the detection end of the torque sensor (3) is connected with the driving main shaft (2), and the torque sensor (3) is used for monitoring the torque generated by the thrust ball bearing (14) during operation.

5. A rolling bearing contact zone lubrication state monitoring device according to claim 3, characterized in that, The loading unit comprises: A support shaft (6) is parallel to the bearing mounting shaft (5), and the upper end of the support shaft (6) is fixed to the base (15); A loading spring (7) is fixed to the upper end of the support shaft (6); A lifting plate (8) is fixed to the lower end of the loading spring (7); A lifting assembly is connected to the lifting plate (8), and is used for driving the lifting plate (8) to move up and down along the vertical direction to compress the loading spring (7), so as to load the axial force on the thrust ball bearing (14).

6. A rolling bearing contact zone lubrication state monitoring device according to claim 5, characterized in that, A load cell (20) is arranged between the loading spring (7) and the support shaft (6), and is used for monitoring the size of the axial force loaded on the thrust ball bearing (14) by the loading spring (7).

7. A rolling bearing contact zone lubrication state monitoring device according to claim 5, characterized in that, The lifting assembly comprises: A rotary driver (11); A lead screw (21) is vertically arranged, the upper end of the lead screw (21) is inserted into the lifting plate (8), a lead screw (21) nut is sleeved on the lead screw (21), the lead screw (21) nut is fixed to the lifting plate (8), the loading spring (7) is sleeved on the upper end of the lead screw (21), and the lower end of the loading spring (7) is fixed to the output shaft of the rotary driver (11); Two light rods (9) are arranged on both sides of the lead screw (21) in parallel and symmetry, the upper and lower ends of the light rod (9) are fixedly connected with support plates (10), respectively, and the lower support plate (10) is fixedly connected with the shell of the rotary driver (11), the lifting plate (8) is sleeved on the two light rods (9), respectively, and the lifting plate (8) is in sliding connection with the light rods (9).

8. A monitoring method of a rolling bearing contact zone lubrication state monitoring device according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: An axial force is applied to the thrust ball bearing (14) to drive the thrust ball bearing (14) to rotate; When the thrust ball bearing (14) moves to a stable state, a constant voltage is applied to the power supply circuit composed of the thrust ball bearing (14), the conductive contact (16), the metal bearing washer (17) and the conductive ball plug (18) through the voltage source, and the real-time current in the power supply circuit is collected through the acquisition module and transmitted to the processing module, the processing module obtains the change peak value of the current in the received current, and when the change peak value of the current reaches a set proportion, the minimum oil film thickness in the thrust ball bearing (14) is determined according to the obtained current peak value and the constant voltage provided by the voltage source, so as to judge the lubrication state of the thrust ball bearing (14).

9. A monitoring method of a rolling bearing contact area lubrication state monitoring device according to claim 8, characterized in that, The minimum oil film thickness in the thrust ball bearing (14) is determined according to the following formula: ， wherein , wherein, h is the oil film thickness, μm; U is the measured voltage drop of the contact zone, V; U IR R is the measured contact resistance of the thrust ball bearing contact zone, ; I is the measured current of the thrust ball bearing contact zone, A; R 0 is the reference resistance, ; h 0 is the characteristic thickness parameter of the thrust ball bearing contact zone, μm; k 1 is the correction coefficient of the surface roughness of the thrust ball bearing contact zone; k 2 is the correction coefficient of the temperature effect on the thrust ball bearing contact zone; k 3 is the correction coefficient of the load effect on the thrust ball bearing contact zone; k 4 is the correction coefficient of the rotational speed shear on the thrust ball bearing contact zone; is the surface roughness of the thrust ball bearing contact zone, is the empirical coefficient, which is between 0.5 and 1.0; T is the measured temperature of the thrust ball bearing contact zone, T 0 is the reference temperature of the thrust ball bearing contact zone, is the temperature coefficient, which is between 0.02 and 0.05; is the axial load of the thrust ball bearing contact zone, is the reference load of the thrust ball bearing contact zone; is the load coefficient, which is between 0.1 and 0.3; n is the rotational speed of the thrust ball bearing; n 0 is the reference rotational speed of the thrust ball bearing; is the rotational speed coefficient, which is between 0.05 and 0.1.​​

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