A controlled clearance cage and method of measuring the frictional resistance thereof

Abstract

The application discloses a retaining cage with controllable gap and a friction resistance measuring method thereof, and belongs to the technical field of mechanical equipment manufacturing. The retaining cage with controllable gap can dynamically adjust the gap between the retaining cage and rolling bodies, and can cooperate with different types of ball-disc testers (rotary type and linear contact type) to measure the friction resistance. The gap between the rolling bodies and the retaining cage can be flexibly adjusted through the adjusting motor and the eccentric wheel, so that the retaining cage body can adapt to the retaining and limiting requirements of different working conditions and different types of bearings, and the performance, service life and reliability of the bearing are significantly improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of mechanical equipment manufacturing, and particularly relates to a cage with controllable clearance and a friction resistance measurement method thereof. BACKGROUND

[0002] Rolling bearing cages are an important component of bearings, used to separate and guide rolling elements, preventing them from colliding with each other, and ensuring uniform distribution of rolling elements between the inner and outer rings of the bearing. The geometry of the cage, material properties, and pocket clearance factors affect the state of the rolling bearing. Understanding the influence of cage pocket clearance factors is of great significance to the operation efficiency and development of the entire mechanical equipment and rolling bearings.

[0003] At present, in most cage model test studies, the pocket clearance is fixed, which cannot adapt to the dynamic needs of different working conditions (such as high speed, heavy load, or temperature changes). Fixed clearance design can easily lead to increased collisions and friction between rolling elements and the cage under high-speed conditions, causing vibration, noise, and temperature rise. In addition, under heavy load or extreme temperature, fixed clearance can cause stress concentration or thermal expansion problems, reducing the reliability and life of the bearing.

[0004] Under high-speed operating conditions, the rolling elements shift towards the outer ring due to centrifugal force, increasing the contact force between the rolling elements and the cage. Fixed clearance cannot effectively respond to this dynamic change, easily causing collisions between the rolling elements and the cage, resulting in additional friction and energy loss. Simultaneously, because fixed clearance cannot effectively absorb the dynamic impacts during high-speed operation, collisions between the rolling elements and the cage induce vibration and generate significant noise. This vibration and noise not only affect the operational stability of the equipment but may also interfere with the surrounding environment. Under heavy-load conditions, the load on the rolling elements increases significantly. Fixed clearance design may lead to uneven distribution of contact stress between the rolling elements and the cage, exacerbating local stress concentration and reducing the strength and durability of the cage. The cage may undergo elastic or plastic deformation due to the limitations of the fixed clearance, causing changes in the pocket shape and further intensifying friction and wear between the rolling elements and the cage. Over long-term operation, this wear will significantly shorten the bearing's service life. Furthermore, the fixed clearance cannot be dynamically adjusted according to load changes, leading to uneven load distribution among the rolling elements. Some rolling elements may bear excessive loads, while others fail to fully utilize their load-bearing capacity, reducing the overall load-bearing efficiency of the bearing. Simultaneously, under temperature variations, the dimensions of bearing components (including the cage and rolling elements) change due to thermal expansion and contraction. The fixed clearance design cannot accommodate this thermal expansion effect, resulting in clearances that are too small at high temperatures or too large at low temperatures, thus affecting the normal operation of the bearing. If the clearance is too small at high temperatures, it can lead to jamming, increased friction, and a sustained rise in temperature, potentially causing bearing failure. If the clearance is too large at low temperatures, it can cause the rolling elements to wobble within the pockets, increasing vibration and noise, while also reducing the bearing's positioning accuracy.

[0005] While existing experimental setups and research methods for bearing cages can simulate bearing operating conditions to some extent, they still have limitations. Some methods, used to test the friction coefficient and wear performance between the cage and rolling elements, typically employ reciprocating or rotary motion to simulate bearing movement. However, these methods cannot fully simulate dynamic friction behavior under high speed, heavy load, or extreme temperatures, and it is difficult to monitor the impact of clearance changes on friction in real time. Other methods, used to test the dynamic performance of cages at high speeds, can only test cages with fixed clearances and cannot dynamically adjust the clearance to adapt to different speeds or loads. Some methods simulate the thermal expansion effect of bearings under extreme temperatures using heating or cooling devices, but it is difficult to precisely control the clearance changes between the cage and rolling elements, and it is impossible to adjust the clearance in real time to compensate for thermal expansion. In summary, most existing devices can only test cages with fixed clearances and cannot simulate the impact of dynamic clearance changes on bearing performance. To overcome the limitations of existing research devices and meet the higher requirements of modern industry for bearing performance, we propose a cage with controllable clearance and a method for measuring its frictional resistance. By dynamically adjusting the clearance between the cage and the rolling elements, the bearing can adapt to different operating conditions (such as high speed, heavy load, and high temperature), thereby significantly improving the bearing's performance, life, and reliability. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a cage with controllable clearance and a method for measuring its frictional resistance. This solves the problem that existing devices can only test cages with fixed clearances and cannot simulate the impact of dynamic clearance changes on bearing performance.

[0007] The present invention is achieved by providing a retainer with controllable clearance, the retainer comprising:

[0008] Adjustable cage body with adjustable clearance to rolling elements;

[0009] A cage moving assembly is disposed on a displacement platform and connected to the cage body for supporting and moving the cage body;

[0010] A gap adjustment section is provided on one side of the displacement platform, and the gap adjustment section is used to drive the cage body and the cage moving assembly;

[0011] The gap adjustment unit includes an adjustment motor, an eccentric wheel, and a motor mounting bracket. The adjustment motor is mounted on the motor mounting bracket, and the eccentric wheel is fixedly sleeved on the outside of the drive shaft of the adjustment motor. The eccentric wheel is arranged corresponding to the cage moving assembly.

[0012] Preferably, the cage body comprises:

[0013] A cage holder, which is mounted on a cage moving assembly;

[0014] A cage pocket is formed within the cage housing, creating an adjustable clearance between the cage pocket and the rolling element.

[0015] Preferably, an L-shaped plate is provided on one side of the displacement platform, and the displacement platform and the L-shaped plate are connected by plate fixing bolts. A seat fixing bolt is provided at the end of the displacement platform to prevent the displacement platform from shaking during testing. A multi-axis drive stage is provided inside the displacement platform to adjust the horizontal and vertical positions of the displacement platform.

[0016] Preferably, the cage moving assembly includes:

[0017] The measuring sensor is connected to the cage seat. The measuring sensor is used to collect the bidirectional pressure between the cage pocket and the rolling element in real time, and convert the pressure signal into an electrical signal to record the change of friction force in real time.

[0018] A dovetail groove is fixedly connected to the measuring sensor, and the dovetail groove is set corresponding to the eccentric wheel;

[0019] The groove guide rail is fixedly installed on the upper surface of the displacement platform and is slidably connected to the dovetail groove. The groove guide rail is used to guide and limit the dovetail groove.

[0020] At least one set of return springs, which are used to control the dovetail groove to return to its original position and assist the eccentric wheel in controlling and adjusting the gap between the bracket hole and the rolling element;

[0021] At least one set of spring fixing bolts are fixedly assembled on the displacement platform, and one end of the spring fixing bolt is fixedly connected to the return spring. The end of the return spring away from the spring fixing bolt is fixedly connected to the dovetail groove.

[0022] Preferably, the measuring sensor is a tension / compression sensor with a measuring range of 5N.

[0023] Preferably, the rolling element is a test steel ball with a diameter of 5.4 mm. The diameter ratio of the rolling element to the cage pocket is 1:1.08. The cage base is made of resin 8000. The rolling element is detachably mounted on the servo motor. A ball-disc testing machine is provided on one side of the rolling element. The contact test bench of the ball-disc testing machine contacts the rolling element, and the surface of the contact test bench is coated with grease. The contact test bench is a rotating contact test bench or a line contact test bench.

[0024] Preferably, the return spring has a hook length of 15mm, an outer diameter of 2mm, and a wire diameter of 0.2mm.

[0025] On the other hand, the present invention also provides a method for measuring cage frictional resistance, the method comprising:

[0026] S10, Test preparation stage: The surfaces of the rolling elements and cage pockets are cleaned sequentially with petroleum ether and anhydrous ethanol. The height of the cage seat is adjusted to align with the center height of the rolling elements using a multi-axis drive table. Lithium-based grease is injected into the cage pockets. The gap between the rolling elements and the cage pockets is adjusted by coordinating the multi-axis drive table and the adjusting motor.

[0027] S20. Before the test begins, use petroleum ether and anhydrous ethanol to clean the surfaces of the contact test bench, rolling elements, and cage pockets. At a rotation speed of 2.0 mm / s, use a syringe and a grease scraper to evenly apply grease to the track of the contact test bench. Then, install the cage with controllable clearance and adjust the height of the cage seat to align with the center height of the rolling elements using a multi-axis drive table. Adjust the clearance between the rolling elements and the cage pockets by adjusting the motor.

[0028] S30: Turn on the servo motor. The servo motor drives the rolling element to rotate. After the rolling element rotates 10 times, its surface is completely covered with grease. Then, the speed of the ball-disc tester is increased to the test set speed. Test data during rolling friction, sliding friction and oil film formation are collected by measuring sensors and high-speed cameras. Among them, the measuring sensors collect the bidirectional pressure between the cage pocket and the rolling element in real time and convert the pressure signal into an electrical signal to record the change of friction force in real time.

[0029] Preferably, when adjusting the gap between the rolling element and the cage pocket by adjusting the motor, the adjusting motor is turned on, the starting of the adjusting motor drives the eccentric wheel to rotate, the eccentric wheel drives the dovetail groove to slide along the groove guide rail, thereby causing the dovetail groove to move the cage seat and the cage pocket, realizing the adjustment of the gap between the rolling element and the cage pocket; during the test phase, the moving distance, speed and time of the dovetail groove are captured by a high-speed camera to obtain the actual experimental distance between the cage pocket and the rolling element.

[0030] Compared with the prior art, the embodiments of this application have the following main advantages:

[0031] The controllable clearance cage provided by this invention can dynamically adjust the clearance between itself and the rolling elements, and can be used with different types of ball-disc testing machines (rotary type, line contact type) to measure frictional resistance. Furthermore, by adjusting the motor and eccentric wheel, the clearance between the rolling elements and the cage pocket can be flexibly adjusted, thereby enabling the cage body to adapt to the holding and limiting requirements of different working conditions and different types of bearings, significantly improving the performance, life and reliability of the bearings.

[0032] In this embodiment of the invention, the clearance adjustment part enables flexible adjustment of the clearance between the rolling element and the cage pocket. On the other hand, by adjusting the motor and the eccentric wheel in linkage, the clearance between the rolling element and the cage pocket can be cyclically adjusted. This allows the cage with controllable clearance to play a better supporting, guiding, protecting and reducing friction multiple roles during movement, and also ensures the performance, life and reliability of the bearing.

[0033] In this embodiment of the invention, the clearance between the rolling element and the cage pocket can be dynamically adjusted according to working conditions through the coordinated cooperation of the clearance adjustment part and the cage moving assembly, thereby improving the performance and life of the bearing. Furthermore, during automatic clearance adjustment, the automatic adjustment of the clearance can be achieved through the cooperation of the measuring sensor and the control system, thereby reducing manual intervention and improving the intelligence level of the bearing. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of a cage with controllable gap provided by the present invention.

[0035] Figure 2 The curve showing the change of friction force over time when the eccentricity of the eccentric wheel is 1 mm is shown.

[0036] Figure 3 The curve showing the change of friction force over time when the eccentricity of the eccentric wheel is 1.5 mm is shown.

[0037] Figure 4 The curve showing the change of friction force over time when the eccentricity of the eccentric wheel is 2 mm is shown.

[0038] Figure 5 The test results are shown with a rolling element speed of 256.0 mm / s and a pocket height of 15.0 mm.

[0039] Figure 6 The test graph shows the range of different eccentric wheel distances over time.

[0040] Figure 7 A schematic diagram of the main structure of the cage is shown during the test of the cylindrical roller-disc line contact test bench.

[0041] In the figure: 1-Cage body, 11-Cage seat, 12-Cage pocket, 2-Cage moving assembly, 21-Measuring sensor, 22-Dovetail groove, 23-Groove guide rail, 24-Reset spring, 25-Spring fixing bolt, 3-Clearance adjustment part, 31-Adjusting motor, 32-Motor fixing bracket, 33-Eccentric wheel, 4-Displacement platform, 41-L-shaped plate, 42-Plate fixing bolt, 43-Seat fixing bolt, 44-Multi-axis drive table, 5-Rolling element. Detailed Implementation

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0043] Most existing devices can only test cages with fixed clearances and cannot simulate the impact of dynamic clearance changes on bearing performance. To overcome the limitations of existing research devices and meet the higher requirements of modern industry for bearing performance, we propose a cage with controllable clearance and a method for measuring its frictional resistance. By dynamically adjusting the clearance between the cage and the rolling element 5, it adapts to the needs of different operating conditions (such as high speed, heavy load, and high temperature), thereby significantly improving the bearing's performance, life, and reliability. In short, the cage with controllable clearance consists of a cage body 1 with an adjustable clearance to the rolling element 5, a cage moving assembly 2, and a clearance adjustment part 3. The clearance adjustment part 3 includes an adjusting motor 31, an eccentric wheel 33, and a motor mounting bracket 32. The controllable clearance cage provided by this invention can dynamically adjust the clearance between itself and the rolling element 5, and can be used with different types of ball-disc testing machines (rotary type, line contact type) to measure frictional resistance. Furthermore, by adjusting the motor 31 and the eccentric wheel 33, the clearance between the rolling element 5 and the cage pocket 12 can be flexibly adjusted, thereby enabling the cage body 1 to adapt to the holding and limiting requirements of different working conditions and different types of bearings, significantly improving the performance, life and reliability of the bearing.

[0044] Example 1

[0045] This invention provides a cage with controllable clearance, such as... Figure 1 As shown, the retainer with controllable clearance specifically includes:

[0046] The cage body 1 is adjustable in terms of clearance with the rolling element 5;

[0047] The cage moving assembly 2 is disposed on the displacement platform 4 and is connected to the cage body 1, and is used to support and move the cage body 1;

[0048] The gap adjustment part 3 is disposed on one side of the displacement platform 4. The gap adjustment part 3 is used to drive the cage body 1 and the cage moving assembly 2.

[0049] The gap adjustment unit 3 includes an adjustment motor 31, an eccentric wheel 33, and a motor mounting bracket 32. The adjustment motor 31 is mounted on the motor mounting bracket 32. The eccentric wheel 33 is fixedly sleeved on the drive shaft of the adjustment motor 31. The eccentric wheel 33 is positioned corresponding to the cage moving assembly 2. The adjustment motor 31 is connected to the motor mounting bracket 32 ​​via a screw. The motor mounting bracket 32 ​​is fixedly assembled below the contact test bench of the ball-disc testing machine by means of snap-fit ​​or bolt connection. The height of the adjustment motor 31 and the eccentric wheel 33 can be adjusted by the screw, so that the eccentric wheel 33 adapts to the cage moving assembly. 2. Height Adjustment: In this embodiment of the invention, the clearance adjustment part 3 enables flexible adjustment of the clearance between the rolling element 5 and the cage pocket 12. Furthermore, by linking the adjusting motor 31 and the eccentric wheel 33, the clearance between the rolling element 5 and the cage pocket 12 can be cyclically adjusted. This allows the cage with controllable clearance to provide better support, guidance, protection, and friction reduction during movement, thus ensuring the performance, lifespan, and reliability of the bearing. The adjusting motor 31 operates at 12V, rotates at 60 rpm, has a power of 15W, and a shaft diameter of 8mm.

[0050] In this embodiment, the eccentric wheel 33 is hollow inside, and the eccentric wheel 33 is fixedly connected to the drive shaft of the adjusting motor 31 by interference fit or snap-fit. The large circle radius of the eccentric wheel 33 is 6mm, the small circle radius is 4mm, and the eccentricity is 2mm.

[0051] The controllable clearance cage provided by this invention can dynamically adjust the clearance between itself and the rolling element 5, and can be used with different types of ball-disc testing machines (rotary type, line contact type) to measure frictional resistance. Furthermore, by adjusting the motor 31 and the eccentric wheel 33, the clearance between the rolling element 5 and the cage pocket 12 can be flexibly adjusted, thereby enabling the cage body 1 to adapt to the holding and limiting requirements of different working conditions and different types of bearings, significantly improving the performance, life and reliability of the bearing.

[0052] In a further preferred embodiment of the present invention, such as Figure 1 As shown, the cage body 1 includes:

[0053] Cage seat 11, which is mounted on cage moving assembly 2;

[0054] A cage pocket 12 is formed in the cage seat 11, and an adjustable gap is formed between the cage pocket 12 and the rolling element 5.

[0055] In this embodiment, the cage seat 11 is a rectangular seat or a round seat, and the cage pocket 12 is a circular groove structure. The rolling element 5 can be a ball bearing, cylindrical roller, needle roller, tapered roller or spherical roller.

[0056] In this embodiment of the invention, an L-shaped plate 41 is provided on one side of the displacement platform 4, and the displacement platform 4 and the L-shaped plate 41 are connected by plate fixing bolts 42. A seat fixing bolt 43 is provided at the end of the displacement platform 4 to prevent the displacement platform 4 from shaking during testing. A multi-axis drive stage 44 is provided inside the displacement platform 4. The multi-axis drive stage 44 is used to adjust the horizontal and vertical positions of the displacement platform 4. The displacement platform 4 can be set in front, rear, left, and right of the rolling element 5 and works in conjunction with the contact test bench of the ball-disc testing machine, so that the cage seat 11 can adapt to the simulation test requirements under different working conditions. The multi-axis drive stage 44 can be a set of X, Y, and Z axis displacement drive stages that cooperate with each other, so that the cage with controllable clearance in this embodiment can be flexibly adjusted in position. The X, Y, and Z axis displacement drive stages can be cylinders or hydraulic cylinders with an accuracy of 0.03 mm. The displacement platform 4 is made of steel.

[0057] In a further preferred embodiment of the present invention, such as Figure 1 As shown, the cage moving assembly 2 includes:

[0058] Measurement sensor 21 is connected to cage seat 11. Measurement sensor 21 is used to collect the bidirectional pressure between cage pocket 12 and rolling element 5 in real time, and convert the pressure signal into an electrical signal to record the change state of friction force in real time. The measurement sensor 21 is a tension-compression sensor with a range of 5N.

[0059] The dovetail groove 22 is fixedly connected to the measuring sensor 21, and the dovetail groove 22 is provided corresponding to the eccentric wheel 33;

[0060] The groove guide rail 23 is fixedly installed on the upper surface of the displacement platform 4 and is slidably connected to the dovetail groove 22. The groove guide rail 23 is used to guide and limit the dovetail groove 22. The dovetail groove 22 can reduce the foot of the cage body 1. At the same time, the eccentric wheel 33 moves the dovetail groove 22 under the drive of the adjusting motor 31. After the dovetail groove 22 moves forward a certain distance, it is pulled back by the reset spring 24. The cycle repeats, thereby realizing a cage structure with controllable gap.

[0061] At least one set of return springs 24 are provided. The return springs 24 are used to control the return of the dovetail groove 22 and assist the eccentric wheel 33 in controlling and adjusting the gap between the bracket hole and the rolling element 5. The return spring 24 has a hook length of 15 mm, an outer diameter of 2 mm, and a wire diameter of 0.2 mm.

[0062] At least one set of spring fixing bolts 25 are fixedly assembled on the displacement platform 4, and one end of the spring fixing bolts 25 is fixedly connected to the return spring 24. The end of the return spring 24 away from the spring fixing bolts 25 is fixedly connected to the dovetail groove 22.

[0063] In this embodiment, the rolling element 5 is a test steel ball with a diameter of 5.4 mm. The test steel ball meets the G5 precision standard. The diameter ratio of the rolling element 5 to the cage pocket 12 is 1:1.08. The cage seat 11 is made of resin 8000. The rolling element 5 is detachably mounted on the servo motor. A ball-disc testing machine is provided on one side of the rolling element 5. The contact test table of the ball-disc testing machine contacts the rolling element 5, and the surface of the contact test table is coated with grease. The contact test table is a rotating contact test table or a line contact test table.

[0064] In this embodiment of the invention, the clearance adjustment part 3 and the cage moving assembly 2 work together to dynamically adjust the clearance between the rolling element 5 and the cage pocket 12 according to working conditions, thereby improving the bearing's performance and lifespan. Furthermore, during automatic clearance adjustment, the cooperation of the measuring sensor 21 and the control system enables automatic clearance adjustment, reducing manual intervention and improving the bearing's intelligence level. To verify the feasibility of this method, this embodiment uses a ball-disc point contact / line contact testing machine for method verification and testing. This invention is also applicable to a cylindrical roller-disc line contact test bench. When testing on the cylindrical roller-disc line contact test bench, the shape of the corresponding cage body 1 changes accordingly. Figure 7 This diagram shows the main structure of the cage during the cylindrical roller-disc line contact test bench. Figure 7 The rolling element 5 is a cylindrical roller.

[0065] Example 2

[0066] This invention also provides a method for measuring cage frictional resistance. The method can be verified and tested using an existing ball-disc point contact / line contact testing machine. Specifically, the cage frictional resistance measurement method includes:

[0067] S10, Test preparation stage: The surfaces of the rolling element 5 and the cage pocket 12 are cleaned sequentially with petroleum ether and anhydrous ethanol, and then dried with nitrogen to ensure the contact surfaces are clean. The height of the cage seat 11 is adjusted to be aligned with the center height of the rolling element 5 by the multi-axis drive stage 44. Lithium-based grease is injected into the cage pocket 12. The gap between the rolling element 5 and the cage pocket 12 is adjusted by the multi-axis drive stage 44 and the adjusting motor 31 in a coordinated manner.

[0068] Specifically, when injecting lithium-based grease into the cage pocket 12, 2.0g of lithium-based grease is injected using a syringe. At the same time, the eccentric wheel 33 is connected to the adjusting motor 31, and the speed of the adjusting motor 31 is controlled, thereby controlling the speed of the eccentric wheel 33. The motor fixing bracket 32 ​​can adjust the height of the adjusting motor 31. During adjustment, the eccentric wheel 33 is required to reach the upper end of the dovetail groove 22. At the same time, the actual experimental distance of the cage can be obtained by using a high-speed camera to capture the forward and backward movement distance, speed and time of the dovetail groove 22.

[0069] To investigate the effect of the clearance between the rolling element 5 and the cage pocket 12, the frictional force of the eccentric wheel 33 was measured in this embodiment for different eccentricities of 1mm, 1.5mm, and 2mm. Figure 2 The curve showing the change of friction force over time when the eccentricity of eccentric wheel 33 is 1 mm is shown. Figure 3 The curve showing the change of friction force over time when the eccentricity of eccentric wheel 33 is 1.5 mm is displayed. Figure 4 The curve showing the change of frictional force over time when the eccentricity of the eccentric wheel 33 is 2 mm is illustrated. Furthermore, this embodiment also measured the frictional force under different clearance conditions. Figure 5 Test results are given for rolling element 5 with a speed of 256.0 mm / s and a pocket height of 15.0 mm. Figure 5 In this configuration, the fixed clearance between the cage and the rolling element 5 is 0.2 mm, wherein the clearance is determined by... Figures 2-4 The curves showing the change in friction force over time for different clearances can be observed. When the eccentricity of the eccentric wheel 33 is 1 mm, the clearance between the cage and the rolling element 5 varies from 0.2 to 1.2 mm. It is clear that when the cage is closest to the rolling element 5, the coefficient of friction is high, and the shear friction is correspondingly maximum. As the clearance gradually increases, the coefficient of friction decreases, and the shear friction decreases accordingly. When the clearance exceeds 1 mm, the friction force becomes zero because the clearance is large enough. Under the same conditions, when the eccentricity of the eccentric wheel 33 is 1.5 mm and 2 mm, the clearance range also increases, and the time for the friction force to decrease from maximum to zero also increases. However, the time for the friction force to remain at zero decreases accordingly. Figure 5 It can be seen that the frictional force changes significantly with different gaps. When the gap is small, the oil film thickness is low, the coefficient of friction is high, and the shear friction is correspondingly large. As the gap gradually increases, the lubricating oil film thickness increases, the coefficient of friction decreases, and the shear friction decreases accordingly.

[0070] S20, before the test begins, the surfaces of the contact test bench, rolling element 5, and cage pocket 12 are cleaned with petroleum ether and anhydrous ethanol. At a rotation speed of 2.0 mm / s, grease is evenly applied to the track of the contact test bench using a syringe and a grease scraper. Then, the controllable clearance cage is installed, and the height of the cage seat 11 is adjusted to align with the center height of the rolling element 5 using the multi-axis drive stage 44. The clearance between the rolling element 5 and the cage pocket 12 is adjusted using the motor 31, and the height is adjusted using the multi-axis drive stage 44 to ensure that the geometric center of the cage is aligned with the center of the rolling element 5. Simultaneously, the position of the dovetail groove 22 is adjusted to change the position of the cage, maintaining an appropriate clearance between the pocket surface and the surface of the rolling element 5.

[0071] In this embodiment of the invention, the mass of the grease is 2.0g, the base oil of the grease used in the experiment is polyalphaolefin (PAO), and the thickener is a lithium-based material.

[0072] S30: The servo motor is turned on, driving the rolling element 5 to rotate. After the rolling element 5 rotates 10 times, its surface is completely covered with grease. Then, the speed of the ball-disc tester is increased to the test set speed. Test data during rolling friction, sliding friction, and oil film formation are collected by the measuring sensor 21 and the high-speed camera. Among them, the measuring sensor 21 collects the bidirectional pressure between the cage pocket 12 and the rolling element 5 in real time, converts the pressure signal into an electrical signal, and records the change in friction force in real time. Figure 6 The test graph shows the range of distance traveled by different eccentric wheels 33 over time.

[0073] In this embodiment, when adjusting the gap between the rolling element 5 and the cage pocket 12 by adjusting the motor 31, the motor 31 is turned on. The motor 31 drives the eccentric wheel 33 to rotate, and the eccentric wheel 33 drives the dovetail groove 22 to slide along the groove guide rail 23, thereby causing the dovetail groove 22 to move the cage seat 11 and the cage pocket 12, thus adjusting the gap between the rolling element 5 and the cage pocket 12. During the test phase, the moving distance, speed and time of the dovetail groove 22 are captured by a high-speed camera to obtain the actual experimental distance between the cage pocket 12 and the rolling element 5.

[0074] In summary, the present invention provides a cage with controllable clearance and a method for measuring frictional resistance. The cage with controllable clearance provided by the present invention can dynamically adjust the clearance between itself and the rolling element 5, and can be used with different types of ball-disc testing machines (rotary type, line contact type) to measure frictional resistance. Furthermore, by adjusting the motor 31 and the eccentric wheel 33, the clearance between the rolling element 5 and the cage pocket 12 can be flexibly adjusted, thereby enabling the cage body 1 to adapt to the holding and limiting requirements of different working conditions and different types of bearings, significantly improving the performance, life and reliability of the bearing.

[0075] It should be noted that, for the sake of simplicity, the foregoing embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0076] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on these embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still combine, add, delete, or otherwise adjust the features of the various embodiments of the present invention according to the circumstances without conflict or creative effort, thereby obtaining different technical solutions that do not fundamentally depart from the concept of the present invention. These technical solutions also fall within the scope of protection of the present invention.

Claims

1. A retainer with controllable clearance, characterized in that, The controllable gap retainer includes: Adjustable cage body with adjustable clearance to rolling elements; A cage moving assembly is disposed on a displacement platform and connected to the cage body for supporting and moving the cage body; A gap adjustment section is provided on one side of the displacement platform, and the gap adjustment section is used to drive the cage body and the cage moving assembly; The gap adjustment part includes an adjustment motor, an eccentric wheel and a motor mounting bracket. The adjustment motor is mounted on the motor mounting bracket. An eccentric wheel is fixedly sleeved on the outside of the drive shaft of the adjustment motor. The eccentric wheel is arranged corresponding to the cage moving assembly. The cage moving assembly includes: The measuring sensor is connected to the cage seat. The measuring sensor is used to collect the bidirectional pressure between the cage pocket and the rolling element in real time, and convert the pressure signal into an electrical signal to record the change of friction force in real time. A dovetail groove is fixedly connected to the measuring sensor, and the dovetail groove is set corresponding to the eccentric wheel; The groove guide rail is fixedly installed on the upper surface of the displacement platform and is slidably connected to the dovetail groove. The groove guide rail is used to guide and limit the dovetail groove. At least one set of return springs, which are used to control the return of the dovetail groove and assist the eccentric wheel in controlling and adjusting the gap between the cage pocket and the rolling element; At least one set of spring fixing bolts are fixedly assembled on the displacement platform, and one end of the spring fixing bolt is fixedly connected to the return spring, and the end of the return spring away from the spring fixing bolt is fixedly connected to the dovetail groove. The cage body includes a cage base, which is mounted on a cage moving assembly; The gap between the rolling element and the cage pocket is adjusted by means of a multi-axis drive table and an adjusting motor working together; An L-shaped plate is provided on one side of the displacement platform, and the displacement platform and the L-shaped plate are connected by plate fixing bolts. A seat fixing bolt is provided at the end of the displacement platform to prevent the displacement platform from shaking during testing. A multi-axis drive stage is provided inside the displacement platform to adjust the horizontal and vertical positions of the displacement platform. When adjusting the clearance between the rolling element and the cage pocket by adjusting the motor, the adjusting motor is turned on. The starting of the adjusting motor drives the eccentric wheel to rotate, and the eccentric wheel drives the dovetail groove to slide along the groove guide rail, thereby causing the dovetail groove to move the cage seat and the cage pocket, thus realizing the adjustment of the clearance between the rolling element and the cage pocket. During the test phase, the moving distance, speed and time of the dovetail groove are captured by a high-speed camera to obtain the actual experimental distance between the cage pocket and the rolling element.

2. The retainer with controllable clearance as described in claim 1, characterized in that: The cage body also includes: A cage pocket is formed within the cage housing, creating an adjustable clearance between the cage pocket and the rolling element.

3. The retainer with controllable clearance as described in claim 2, characterized in that: The measuring sensor is a tension / compression sensor with a measuring range of 5N.

4. The retainer with controllable clearance as described in claim 2, characterized in that: The rolling element is a test steel ball with a diameter of 5.4 mm. The diameter ratio of the rolling element to the cage pocket is 1:1.

08. The cage base is made of resin 8000. The rolling element is detachably mounted on the servo motor. A ball-disc tester is provided on one side of the rolling element. The contact test bench of the ball-disc tester contacts the rolling element, and the surface of the contact test bench is coated with grease. The contact test bench is a rotational contact test bench or a line contact test bench.

5. The retainer with controllable clearance as described in claim 4, characterized in that: The return spring has a hook length of 15mm, an outer diameter of 2mm, and a wire diameter of 0.2mm.

6. A method for measuring cage frictional resistance based on the controllable clearance cage of claim 5, characterized in that: include: S10, Test preparation stage: Use petroleum ether and anhydrous ethanol to clean the surfaces of the rolling elements and cage pockets in sequence. Adjust the height of the cage seat to align with the center height of the rolling elements using a multi-axis drive table. Inject lithium-based grease into the cage pockets. S20. Before the test begins, use petroleum ether and anhydrous ethanol to clean the surfaces of the contact test bench, rolling elements, and cage pockets. At a rotation speed of 2.0 mm / s, use a syringe and a grease scraper to evenly apply grease to the track of the contact test bench. Then, install the cage with controllable clearance and adjust the height of the cage seat to align with the center height of the rolling elements using a multi-axis drive table. Adjust the clearance between the rolling elements and the cage pockets by adjusting the motor. S30: Turn on the servo motor. The servo motor drives the rolling element to rotate. After the rolling element rotates 10 times, its surface is completely covered with grease. Then, the speed of the ball-disc tester is increased to the test set speed. Test data during rolling friction, sliding friction and oil film formation are collected by measuring sensors and high-speed cameras. Among them, the measuring sensors collect the bidirectional pressure between the cage pocket and the rolling element in real time and convert the pressure signal into an electrical signal to record the change of friction force in real time.

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