Bearing oil lubrication test structure for low-temperature variable-load working condition

Abstract

The invention belongs to the field of oil fluid elastohydrodynamic lubrication test, and discloses a bearing oil lubrication test structure for a low-temperature variable-load working condition, which comprises an optical film thickness measurement module, an optical friction disc assembly, a loading mechanism, a replaceable roller module and a low-temperature control module. The thermoelectric semiconductor refrigeration assembly is adopted, low-temperature and ultralow-temperature lubrication conditions can be accurately and rapidly provided, control is stable, and temperature uniformity is good; by adopting electric-pneumatic combined loading, a dynamic load spectrum can be generated, the response is fast, and the precision is high; the friction disc and the roller are independently controlled by two servo motors, and the entrainment speed u and the sliding-rolling ratio SRR can be freely set according to experiment requirements. The structure integrates the in-situ measurement capability of multiple parameters such as friction torque, oil film thickness and vibration, the lubrication state of a contact area is monitored in real time, and hardware assistance is provided for deep research on low-temperature variable-load elastohydrodynamic lubrication.

Description

Technical Field

[0001] The present invention belongs to the field of oil elastohydrodynamic lubrication testing and relates to a bearing oil lubrication test structure for low-temperature variable load conditions, which is used to test the oil film distribution characteristics, wear degree and traction characteristics between ball bearing rollers and raceways under extreme working conditions. Background Art

[0002] Rolling bearings are widely used in various engineering fields, including automobiles, aircraft, and machine tools. The reliability and stability of bearings depend largely on their lubrication status. A good lubricating oil film can effectively reduce wear, ensure load-bearing capacity, and improve the kinematic performance and service life of components. In recent years, the demand for rolling bearings in extreme service environments has increased, such as in aircraft engines, offshore wind turbines, and polar icebreakers. For example, polar icebreakers require bearings to operate under ultra-low temperatures, high loads, and shock loads. The rheological behavior of lubricants deviates from classical lubrication theory, exhibiting significant non-Newtonian characteristics and complex thermal-fluid-solid coupling effects. They can also experience oil-starved lubrication and boundary film effects, which can easily lead to oil film failure, increased wear, and even bearing seizure. Therefore, it is necessary to simulate and test the above-mentioned operating conditions in the laboratory in advance to ensure the reliability of the bearings during actual service.

[0003] Existing bearing lubrication testing machines are divided into two categories. One is for bearing models, which have a complete structure, including inner and outer rings, rollers and cages; the other is for roller-raceway models, that is, ball-disc friction structures, which use a single roller to rotate against a plane. Under most working conditions, the lubricating oil film thickness of rolling bearings is less than 1μm and the contact area is less than 1mm. 2 , so the curvature of the raceway itself can be ignored for research, and the roller-raceway model is quite reasonable and reliable. Most of the existing testing machines are designed for normal and high temperature working conditions, and the temperature control system cannot provide a lubrication environment below room temperature. In addition, for the loading mechanism, most of the existing test benches provide a constant load and cannot simulate the more common cyclic and impact loads in engineering. In recent years, some equipment manufacturers and university laboratories have gradually begun to study the lubrication characteristics of bearings under low-temperature and variable load conditions, and have developed corresponding test structures.

[0004] Chinese patent CN201610536269.0 discloses "A high- and low-temperature lubrication test device and control method for high-speed bearings of aircraft engines", which includes an oil supply system, a heating system, a test system, an oil return cooling system and a circulating heat dissipation system in series. The lubricating oil can be heated by electric heating alone or by using an electric heating rod and an electric heater at the same time through an electromagnetic reversing valve according to the target working conditions. The main oil tank and the auxiliary oil tank are independently set, and the first circulating pump is used for local heat dissipation, and the second circulating pump is used for circulating heat dissipation. The device is controlled by a host computer, a PLC and multiple sensors. It has a high degree of automation and a simple structure, is easy to operate, and is conducive to promotion. However, the device is not designed for loading methods. It is mainly used for simulation tests in high and low temperature environments, and cannot obtain the lubrication characteristics of the roller contact area.

[0005] In order to test the elastohydrodynamic lubrication performance between bearing rollers and raceways, especially under low temperature and variable load conditions, it is urgent to develop a dedicated test structure that can effectively simulate the above conditions and accurately measure key lubrication properties. Summary of the Invention

[0006] In view of the above problems existing in the prior art, the present invention designs a test device that can test the oil film characteristics between the roller and the raceway of a ball bearing under low temperature and variable load conditions.

[0007] The technical solution of the present invention:

[0008] A bearing oil lubrication test structure for low-temperature and variable-load conditions, comprising an optical film thickness measurement module, an optical friction disc assembly, a loading mechanism, a replaceable roller module, and a low-temperature control module;

[0009] The optical film thickness measurement module is used to measure the oil film thickness distribution in the contact area between the roller and the friction disc. It uses optical interferometry as the basic measurement principle and includes a CCD high-speed camera 1, an optical module 2, and a spectrometer 3. The optical module 2 includes a lens, a lens holder, and a light source. The light source is mounted on the lens holder, and the spectrometer 3 is built into the lens. The CCD high-speed camera 1 is mounted above the lens holder and connected to a PC-based 3D oil film imaging and analysis system. The optical film thickness measurement module uses interferometry to capture the contact area between the roller and the friction disc, and analyzes the oil film thickness distribution in the contact area between the roller and the friction disc based on the interference fringes.

[0010] The optical friction disc assembly is used to install and lock the nano-scale optical friction disc 5 and is driven to rotate by a motor. The optical friction disc assembly includes the nano-scale optical friction disc 5, a friction disc locking nut 4, a friction disc support ball joint 15, a friction disc drive shaft 14, and a torque sensor 16. The torque sensor 16 is installed between the friction disc drive shaft 14 and an external servo motor. The servo motor provides power to the friction disc drive shaft 14 and the torque sensor 16. The friction coefficient is obtained by measuring the output torque of the torque sensor 16. The nano-scale optical friction disc 5 is made of organic glass, and its lower surface is coated with silicon dioxide for generating an interference pattern. The nano-scale optical friction disc 5 is assembled to the friction disc drive shaft 14 via a key connection and is fixed by the friction disc locking nut 4. The lower contact surface of the nano-scale optical friction disc 5 contacts the friction disc support ball joint 15 and the replaceable roller member 8. The optical friction disc assembly rotates at a set speed under the drive of the servo motor.

[0011] The loading mechanism is used to apply an external load to the replaceable roller module and includes a piezoelectric force-measuring element 10 and a loading mechanism connecting rod 13. The piezoelectric force-measuring element 10 is mounted on the upper end of the loading mechanism connecting rod 13 and is connected to the replaceable roller module to detect changes in the load at the contact area between the roller and the friction disc. The external dynamic load is transmitted to the contact area between the roller and the friction disc via the loading mechanism connecting rod 13 using electric-pneumatic combined loading.

[0012] The replaceable roller module is used to simulate the roller structure of a rolling bearing and is mainly composed of a roller shaft support bearing 6, a roller shaft 7, a replaceable roller part 8, a roller floating bearing seat 9 and an oil pool 11; wherein, the roller floating bearing seat 9 is assembled with the oil pool 11, and the roller floating bearing seat 9 is connected to the loading mechanism connecting rod 13 of the loading mechanism below through a piezoelectric force measuring element 10, and a negative pressure oil suction hole is provided on the wall of the oil pool to facilitate the discharge of lubricating oil; there are three roller shaft support bearings 6, two of which are matched with the roller shaft 7 in a simply supported manner, and the other is used to connect the roller shaft 7 and the experimental table to constrain the freedom of the roller shaft 7; the replaceable roller part 8 is installed on the roller shaft 7, and the replaceable roller part 8 is replaced according to the requirements of the experimental point contact or line contact. According to the Hertz pressure requirements of the contact area between the roller and the friction disk in the experiment, the material of the replaceable roller part 8 can be selected from bearing steel, silicon carbide, etc.; the roller shaft 7 is driven by an external servo motor and rotates at a set speed;

[0013] The low-temperature control module is a thermoelectric semiconductor refrigeration component 12. The cooling surface is attached to the bottom of the oil pool 11 to ensure that the contact surface is clean and prevent oil and dust from affecting the cooling effect. The thermoelectric semiconductor refrigeration component 12 is connected to the control system. The temperature can be manually set before the experiment, and the lowest temperature can reach minus 55°C.

[0014] Beneficial effects of the present invention:

[0015] 1. Low temperature lubrication environment simulation: The use of thermoelectric semiconductor refrigeration components can accurately and quickly provide low temperature and ultra-low temperature lubrication conditions in the contact area between the roller and the raceway, with stable control and good temperature uniformity.

[0016] 2. Variable load conditions: Electric-pneumatic composite loading is used to generate dynamic load spectra (sine, impact, etc.) in low temperature environments, with a wide loading range, fast response and high accuracy.

[0017] 3. Adjustable entrainment speed and slip-roll ratio: The rotation of the friction disc and roller is controlled by two servo motors, so the entrainment speed u and slip-roll ratio SRR can be freely set according to experimental needs. The relevant calculation formula is given here. Assuming the rotation speeds of the friction disc and roller are u1 and u2 respectively, we have:

[0018]

[0019] 4. In-situ measurement of lubrication test: The structure described in the present invention integrates the in-situ measurement capabilities of multiple parameters such as friction torque, oil film thickness, and vibration, and monitors the lubrication status of the contact area in real time, providing hardware assistance for the study of low-temperature variable-load elastohydrodynamic lubrication. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the present invention.

[0021] In the figure: 1. CCD high-speed camera, 2. Optical module, 3. Spectrometer, 4. Friction disc locking nut, 5. Nano-optical friction disc, 6. Roller shaft support bearing, 7. Roller shaft, 8. Replaceable roller component, 9. Roller floating bearing seat, 10. Piezoelectric force measuring element, 11. Oil pool, 12. Thermoelectric semiconductor cooling component, 13. Loading mechanism connecting rod, 14. Friction disc drive shaft, 15. Friction disc support ball joint, 16. Torque sensor. DETAILED DESCRIPTION

[0022] The specific implementation of the present invention is described in detail below in conjunction with the technical solutions and drawings.

[0023] like Figure 1 As shown, a bearing oil lubrication test structure for low-temperature and variable-load conditions includes an optical film thickness measurement module, an optical friction disk assembly, a loading mechanism, a replaceable roller module, and a low-temperature control module.

[0024] The optical film thickness measurement module is used to measure the oil film distribution in the contact area between the roller and the friction disk. An external light source enters the lens through the light hole on the lens holder. The light is split into two beams by the spectrometer 3. One beam is directed to the contact area and reflected multiple times by the glass coating. The other beam directly returns to the CCD high-speed camera 1. The oil film thickness distribution is then calculated by the 3D oil film imaging analysis system (not shown in the figure).

[0025] The optical friction disc assembly is used to install and lock the friction disc. The servo motor drives the friction disc drive shaft 14-1. The optical friction disc 5 is keyed to the shaft 14 and fixed by the lock nut 4. The torque sensor 16 is installed on the drive shaft. The output torque measured by the torque sensor 16 is used to obtain the friction coefficient.

[0026] The loading mechanism is used to apply an external load to the roller module, using electric-pneumatic composite loading. The load is transmitted to the contact area between the roller and the friction disk through the loading mechanism connecting rod 13. The piezoelectric force measuring element 10 located at the upper end of the loading mechanism connecting rod 13 outputs the pressure of the contact area to the control end, thereby obtaining a dynamic load spectrum of the roller and the friction disk.

[0027] The replaceable roller module is used to simulate the roller structure of a rolling bearing. The roller shaft 7 is driven by a servo motor. The roller shaft 7 is connected to the experimental platform base and the roller floating bearing seat 9 by three roller shaft support bearings 6. The replaceable roller member 8 is installed on the roller shaft 7 by bolts. The roller is replaced according to the experimental requirements of point contact or line contact. Lubricating oil is added to the oil pool 11 and discharged through the negative pressure oil suction hole on the wall of the oil pool after the experiment.

[0028] The low temperature control module is used to provide low temperature working conditions and adopts thermoelectric semiconductor refrigeration component 12 for cooling. Its cooling surface is attached to the bottom of the oil pool and connected to the control system. The temperature can be manually set before the experiment, and the lowest temperature can reach -55°C.

[0029] The method of use of the present invention is:

[0030] The first step is to add an appropriate amount of lubricating oil to the oil pool 11;

[0031] The second step is to install the required rollers according to the test requirements of point contact or line contact;

[0032] The third step is to install the friction disc locking nut 4 and the nano-optical friction disc 5;

[0033] Step 4: Set the speed and start the motor to make the replaceable roller 8 and the nano-optical friction disk 5 start to idle;

[0034] Step 5: Start the loading mechanism and the piezoelectric force measuring element 10, and slowly load until the replaceable roller 8 and the nano-optical friction disk 5 just come into contact;

[0035] Step 6: Start the thermoelectric semiconductor refrigeration component 12, set the required test temperature, and wait for the oil pool 11 to stabilize to the target temperature;

[0036] Step 7: Set the variable load parameters and apply external load to the roller floating bearing seat 9;

[0037] Step 8: Lower the lens, turn on the external light source, and focus on the contact area until a clear interference pattern can be observed;

[0038] Step 9: Collect and record friction torque, oil film state, load parameters, etc. in real time;

[0039] Step 10: Analyze the data and evaluate the lubrication characteristics.

[0040] In the eleventh step, the external load is removed, the negative pressure oil suction is started, the lubricating oil in the oil pool 11 is drained, the optical film thickness measurement module is raised, the servo motor is stopped, the replaceable roller part 8 and the nano-optical friction disk 5 are disassembled, and the experiment is ended.

Claims

1. A bearing oil lubrication test structure for low temperature and variable load conditions, characterized in that: The bearing oil lubrication test structure for low-temperature variable load conditions includes an optical film thickness measurement module, an optical friction disc assembly, a loading mechanism, a replaceable roller module, and a low-temperature control module; The optical film thickness measurement module is used to measure the oil film thickness distribution in the contact area between the roller and the friction disk, and uses optical interferometry as the basic measurement principle, and includes a CCD high-speed camera (1), an optical module (2) and a spectrometer (3); wherein the optical module (2) includes a lens, a lens bracket and a light source, the light source is mounted on the lens bracket, and the spectrometer (3) is built into the lens; a CCD high-speed camera (1) is mounted above the lens bracket and connected to a PC-side 3D oil film imaging analysis system; the optical film thickness measurement module uses interferometry to photograph the contact area between the roller and the friction disk, and analyzes the oil film thickness distribution in the contact area between the roller and the friction disk based on interference fringes; The optical friction disc assembly is used to install and lock the nano-scale optical friction disc (5) and is driven to rotate by a motor; the optical friction disc assembly comprises a nano-scale optical friction disc (5), a friction disc locking nut (4), a friction disc supporting ball joint (15), a friction disc driving shaft (14) and a torque sensor (16); wherein the torque sensor (16) is installed between the friction disc driving shaft (14) and an external servo motor, the servo motor provides power to the friction disc driving shaft (14) and the torque sensor (16), and the friction coefficient is obtained by the output torque measured by the torque sensor (16); the nano-scale optical friction disc (5) is assembled to the friction disc driving shaft (14) through a key connection and is fixed by the friction disc locking nut (4); the lower contact surface of the nano-scale optical friction disc (5) contacts the friction disc supporting ball joint (15) and the replaceable roller member (8); the optical friction disc assembly rotates at a set speed under the drive of the servo motor; The loading mechanism is used to apply an external load to the replaceable roller module, and includes a piezoelectric force measuring element (10) and a loading mechanism connecting rod (13); wherein the piezoelectric force measuring element (10) is installed at the upper end of the loading mechanism connecting rod (13) and is connected to the replaceable roller module, and is used to detect the load change in the contact area between the roller and the friction disk; an electric-pneumatic composite loading method is used to transmit the external dynamic load to the contact area between the roller and the friction disk through the loading mechanism connecting rod (13); The replaceable roller module is used to simulate the roller structure of a rolling bearing, and is mainly composed of a roller shaft support bearing (6), a roller rotating shaft (7), a replaceable roller component (8), a roller floating bearing seat (9) and an oil pool (11); wherein the roller floating bearing seat (9) and the oil pool (11) are assembled together, and the roller floating bearing seat (9) is connected to the loading mechanism connecting rod (13) of the loading mechanism below through a piezoelectric force measuring element (10), and a negative pressure oil suction hole is provided on the wall of the oil pool to facilitate the discharge of lubricating oil; there are three roller shaft support bearings (6), two of which are matched with the roller rotating shaft (7) in a simply supported manner, and the other is used to connect the roller rotating shaft (7) and the experimental table to constrain the degree of freedom of the roller rotating shaft (7); the replaceable roller component (8) is installed on the roller rotating shaft (7); the roller rotating shaft (7) is driven by an external servo motor and rotates according to a set speed; The low-temperature control module is a thermoelectric semiconductor refrigeration component (12), and the refrigeration surface is attached to the bottom of the oil pool (11) to ensure that the contact surface is clean and avoid oil and dust affecting the refrigeration effect. The thermoelectric semiconductor refrigeration component (12) is connected to the control system.

2. The bearing oil lubrication test structure for low temperature and variable load conditions according to claim 1 is characterized in that: The nanometer-scale optical friction disk (5) is made of organic glass, and its lower surface is coated with silicon dioxide, which is used to generate interference patterns.

3. The bearing oil lubrication test structure for low temperature and variable load conditions according to claim 1 is characterized in that: The replaceable roller member (8) is replaced according to the requirements of the experimental point contact or line contact, and according to the Hertz pressure requirements of the contact area between the roller and the friction disk in the experiment.

4. The bearing oil lubrication test structure for low temperature and variable load conditions according to claim 1, characterized in that: The material of the replaceable roller element (8) is bearing steel or silicon carbide.

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