Bearing micro-friction torque test platform based on fiber bragg grating

Abstract

The invention relates to a fiber bragg grating-based bearing micro-friction torque test platform, which comprises a test bench, a driving shaft and a friction torque test device, the driving shaft and the friction torque test device are arranged on the test bench, the friction torque test device comprises a connecting beam, a fiber bragg grating sensor and a lever, and the friction torque is tested through the cooperation of the lever, a sucker and the connecting beam. A high-precision and real-time measurement and evaluation scheme can be provided for friction torque measurement of the bearing, the limitation of a traditional electric measurement torque sensor in tiny torque measurement is overcome by utilizing the characteristics of high sensitivity, wide range and electromagnetic interference resistance of the optical fiber sensor, the friction torque can be accurately measured by using the test platform, and the measurement accuracy is improved. The device is especially suitable for measuring micro friction torque, and has the advantages of high precision, interference resistance, strong real-time performance, convenient use and the like.

Description

Technical Field

[0001] The invention relates to the technical field of bearing friction torque testing, and in particular to a bearing micro-friction torque testing platform based on optical fiber grating. Background Art

[0002] The friction torque of a bearing is an important parameter that reflects the working state of the bearing, and directly affects the operating efficiency and service life of mechanical equipment. Traditional friction torque measurement methods mostly rely on mechanical sensors. Although they can provide a certain test accuracy, their measurement process is easily affected by changes in the external environment, contact interference, and wear and tear from long-term use, resulting in reduced data accuracy. In addition, traditional methods have limited ability to measure tiny friction torques, especially in situations where high precision is required, and there are large errors.

[0003] With the rapid development of fiber Bragg grating technology, the friction torque measurement method based on fiber optic sensing has gradually become an ideal solution. Fiber Bragg grating sensors have the advantages of high sensitivity, high precision, and anti-electromagnetic interference, and can accurately measure mechanical parameters in complex environments. By utilizing the relationship between the tiny deformation of fiber Bragg grating and the reflection wavelength, real-time and accurate detection of tiny friction torque can be achieved.

[0004] However, the existing fiber Bragg grating-based friction torque test platform is mostly targeted at specific application scenarios, and it is difficult to meet the high-precision measurement requirements of bearings. In particular, there are still certain limitations in the test accuracy, response speed, and environmental adaptability of small friction torques, and the real-time and anti-interference capabilities are insufficient. Therefore, the development of a high-precision micro-friction torque test platform based on fiber Bragg grating technology has important research and application value, which can improve the accuracy and reliability of bearing tests and provide strong support for the design and optimization of high-performance mechanical equipment. Summary of the invention

[0005] In view of the defects of the prior art, the present invention proposes a bearing micro-friction torque test platform based on fiber grating, aiming to solve the common problems of low accuracy, insufficient real-time performance and anti-interference ability in micro-friction torque testing.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A bearing micro-friction torque test platform based on fiber grating includes a test bench, a drive shaft installed on the test bench and a friction torque test device, the inner ring of the bearing to be tested is installed on the drive shaft, the friction torque test device is closely fitted with the outer ring of the bearing to be tested for measurement, the friction torque test device includes a shell, a connecting beam, a fiber grating sensor and a lever, the two ends of the connecting beam are respectively fixed on the shell, the lever is vertically fixedly connected to the midpoint of the connecting beam to form a "T"-shaped structure, the "T"-shaped structure is located on a plane perpendicular to the drive shaft and aligned with the bearing to be tested, the fiber grating sensors are symmetrically arranged on the connecting beams on both sides of the lever, a support rod is hinged on one side of the lever close to the connecting beam, the other end of the support rod is fixed on the shell, and a suction cup is installed on the other end of the lever, and the suction cup is adsorbed on the outer ring of the bearing during testing.

[0008] Furthermore, the hinge point between the support rod and the lever divides the lever into two parts, a long end and a short end, the short end is located at one end close to the connecting beam, and the ratio of the short end to the long end is preferably 1:5.

[0009] Furthermore, the material used for the connecting beam is nylon plastic.

[0010] Furthermore, the driving shaft is connected to a motor to drive the inner ring of the bearing to be tested to rotate.

[0011] Furthermore, the test bench is also provided with a rib, which is arranged on the opposite side of the suction cup. The rib is in slight clearance contact with the outer ring of the bearing to be tested to prevent the rolling element of the bearing from shifting during rotation.

[0012] Furthermore, the contact gap between the rib and the outer ring of the bearing to be tested is 0.01 mm-0.1 mm.

[0013] Furthermore, the position of the rib is adjustable to accommodate bearings of different models.

[0014] Furthermore, the bearing friction torque measured by the friction torque testing device is: M = ε·A·E·L1; wherein A is the cross-sectional area of ​​the connecting beam, E is the elastic modulus of the connecting beam, and L1 represents the length of the short end of the lever; the strain k is the strain sensitivity coefficient of the fiber Bragg grating central wavelength drift, λ0 is the original wavelength of the fiber Bragg grating sensor, and △λ1 is the wavelength change caused by the deformation of the fiber Bragg grating sensor due to force, which is obtained in real time by the signal acquisition instrument.

[0015] Beneficial effects: The bearing micro-friction torque test platform of the present invention is built based on fiber optic Bragg grating sensing technology. Through the cooperation of levers, suction cups and connecting beams, it can provide a high-precision, real-time measurement and evaluation solution for bearing friction torque measurement. The high sensitivity, wide range and anti-electromagnetic interference characteristics of optical fiber sensors are utilized to overcome the limitations of traditional electrical torque sensors in tiny torque measurements. The test platform can accurately measure friction torque, which is particularly suitable for measuring tiny friction torques. It has the advantages of high precision, anti-interference, strong real-time performance and easy use. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the bearing micro-friction torque test platform of the present invention;

[0017] Figure 2 Schematic diagram of the internal structure of the friction torque testing device of the present invention (top view);

[0018] Figure 3 Schematic diagram of the friction torque testing device of the present invention (top view).

[0019] Reference numerals:

[0020] 1 test bench, 2 friction torque test device, 3 driving shaft, 4 bearing to be tested, 5 motor, 6 connecting beam, 7 lever, 8 support rod, 9 suction cup, 10 fiber grating sensor, 11 housing, 12 rib. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] like Figure 1 As shown, a bearing micro-friction torque test platform based on fiber grating includes a test bench 1, a drive shaft 3 installed on the test bench 1, and a friction torque test device 2, wherein the inner ring of the bearing 4 to be tested is installed on the drive shaft 3 and driven to rotate by a motor 5, and the friction torque test device 2 is tightly fitted with the outer ring of the bearing 4 to be tested for measurement.

[0023] like Figure 1-3 As shown, the friction torque test device 2 includes a housing 11 and a connecting beam 6, a fiber grating sensor 10 and a lever 7 encapsulated in the housing 11. The two ends of the connecting beam 6 are respectively fixed on the housing 11. The lever 7 is vertically fixedly connected to the midpoint of the connecting beam 6 to form a "T"-shaped structure. The "T"-shaped structure is located on a plane perpendicular to the drive shaft 3 and aligned with the bearing 4 to be tested. Figure 1In the illustrated embodiment, the drive shaft 3 is vertically arranged, and the "T"-shaped structure is located on a horizontal plane and is consistent with the height of the bearing 4 to be tested. A suction cup 9 is installed at the other end of the lever 7, and the suction cup 9 is adsorbed on the outer ring of the bearing during testing; fiber grating sensors 10 are symmetrically arranged on the connecting beams 6 on both sides of the lever 7, and a support rod 8 is hinged on the lever 7, and the other end of the support rod 8 is fixed on the housing 11 and parallel to the connecting beam 6. The hinge point between the support rod 8 and the lever 7 divides the lever 7 into a long end and a short end. The side close to the connecting beam 6 is the short end, and the side close to the bearing 4 to be tested is the long end.

[0024] Since the friction torque of the bearing is usually small, the accuracy of direct measurement is difficult to control. Therefore, the present invention designs a lever 7 in the test device to increase the measuring force through the amplifying effect of the lever 7. Since the friction torque M=F*L, the torques on the left and right sides of the lever 7 are equal. Therefore, if L2 is larger than L1, the force at the right end will be amplified when transmitted to the left end. The long end (L2) of the lever 7 is usually designed to be much longer than the short end (L1). Such a design helps to amplify the smaller force at the long end (close to the bearing end) to the short end (one end of the connecting beam) through the principle of the lever 7, so that the tiny friction torque produces a larger force, which is convenient for more accurate measurement at the short end through the connecting beam 6 and the fiber grating.

[0025] In some specific embodiments, considering the force difference, space limitation and precision requirement, a 5:1 ratio between the long end and the short end of the lever is a reasonable choice, which can ensure the torque balance without excessively increasing the length of the lever 7, resulting in space waste or complication of the mechanical device.

[0026] like Figure 2-3 As shown, fiber grating sensors FBG1 and FBG2 are symmetrically arranged on both sides of the midpoint of the connecting beam 6, the left end of the lever 7 is fixedly connected to the midpoint of the connecting beam 6, and the right end of the lever 7 is a suction cup 9. Using the suction cup 9 as the probe end of the bearing friction torque detection device has many advantages, especially in improving measurement stability, simplifying operation, reducing damage to bearings, and adapting to bearings of different specifications. The suction cup design makes the detection device more flexible and efficient, and can provide accurate friction torque data under various working conditions, thereby improving the health monitoring capability and fault prediction accuracy of the equipment. The connecting beam 6 is generally made of nylon plastic, which has a certain deformation ability.

[0027] Furthermore, a rib 12 is provided on the test bench 1, and the rib 12 is in micro-contact with the bearing 4 to be tested. When measuring the bearing friction torque, the rib 12 can limit the axial displacement of the bearing under high load or high speed or prevent the bearing rolling element from shifting due to force, thereby ensuring that the rolling element remains on a suitable running track; it can also reduce the friction torque fluctuation caused by the offset or uneven distribution of the bearing rolling element, thereby making the measurement result more accurate and stable.

[0028] In bearing design, the optimal degree of contact between the rib 12 and the outer ring of the bearing is usually referred to as "micro-gap contact". This micro-gap contact means that the contact pressure and gap between the rib 12 and the outer ring of the bearing are very small, usually at the micron level. In an embodiment of the present invention, the gap between the contact surfaces is controlled within a very small range, usually between 0.01 mm and 0.1 mm. This tiny gap can effectively prevent the rib 12 from causing excessive friction to the outer ring, while maintaining the restraining effect of the rib 12 on the rolling element to prevent axial displacement.

[0029] When the test platform is in use, the suction cup 9 of the friction torque test device 2 fits tightly against the outer ring of the bearing 4 to be tested, and the drive shaft 3 fits tightly against the inner ring of the bearing 4 to be tested. When measuring the bearing friction torque, maintaining the balance of the bearing outer ring and appropriate preload is the key to ensuring measurement accuracy. The rib 12 is in slight contact with the bearing to provide support, and the rib 12 can be flexibly adjusted to suit bearings of different models. When the motor 5 is running, the drive shaft 3 drives the inner ring of the bearing to rotate. At this time, the friction torque is usually due to the rotation of the inner ring acting on the rolling element, and the rolling element then generates friction with the contact surface of the outer ring, driving the outer ring to rotate. The outer ring of the bearing is tightly fitted with the right end of the lever 7 through the suction cup 9, which drives the lever 7 to rotate along with the outer ring of the bearing.

[0030] During the test, the fiber grating sensor 10 is connected to the PC end. When the bearing is in operation, the lever 7 rotates with the outer ring of the bearing. Under the action of force, one end of the connecting beam 6 at the left end of the lever 7 is compressed and the other end is pulled, resulting in deformation. The working principle of the fiber grating is essentially based on the reflection phenomenon of light caused by periodic changes in the refractive index, and external factors such as deformation and temperature will affect the structure of the fiber grating, thereby changing its reflection wavelength. The wavelength change of the fiber grating can be collected and processed by the corresponding software. After the wavelength change is obtained, the stress of the connecting beam 6 can be obtained according to the relationship between wavelength and strain and Hooke's law, and then the friction torque can be obtained, that is, the measurement of the bearing friction torque can be realized.

[0031] Assume that the rotation direction of lever 7 is Figure 2As shown, when the lever 7 rotates, it will pull the connecting beam 6 to produce deformation. One of the two fiber grating sensors 10 on the connecting beam 6 is subjected to tension and the other is subjected to compression. The wavelength signal of the fiber grating sensor 10 is obtained in real time by a signal acquisition instrument, and the wavelength change of the fiber grating is set to be positive when it is pulled and negative when it is compressed. Figure 2-3 middle:

[0032] The wavelength change of FBG1 above due to compression deformation is △λ A =-△λ1+△λ2;

[0033] The wavelength change of FBG2 below due to tension is △λ B =△λ1+△λ2;

[0034] Wherein, Δλ1 is the wavelength variation of the fiber Bragg grating sensor 10 caused by deformation due to force, and Δλ2 is the wavelength variation of the fiber Bragg grating sensor 10 caused by changes in ambient temperature.

[0035] Since the two fiber Bragg gratings are arranged symmetrically, the total wavelength change of the measured fiber Bragg grating is △λ B -△λ A =2△λ1, it can be seen that this device can increase the sensitivity of the fiber Bragg grating sensor and compensate for the influence of temperature on the fiber Bragg grating sensor.

[0036] According to the relationship between strain and wavelength, the total strain of the connecting beam 6 can be obtained: k is the strain sensitivity coefficient of the fiber Bragg grating center wavelength drift, and λ0 is the original wavelength of the fiber Bragg grating working wavelength.

[0037] According to the strain and Hooke's law, the stress on the cross section of the connecting beam 6 can be calculated: F = ε × A × E, and then the stress multiplied by the lever arm is the friction torque M transmitted by the lever 7. 左 =M 右 =ε·A·E·L1, where A is the cross-sectional area of ​​the connecting beam 6, and E is the elastic modulus of the connecting beam 6. In the lever device, L1 and L2 represent the lengths of the left and right ends of the lever 7, respectively. Due to the friction torque M=F*L, the torque M on the left and right sides of the lever 7 is 左 and M 右 Therefore, if L2 is larger than L1, the force at the right end will be amplified when transmitted to the left end, thereby improving the measurement accuracy.

[0038] In summary, the present invention provides a high-precision, real-time measurement and evaluation solution for the friction torque measurement of bearings. It utilizes the high sensitivity, wide range and anti-electromagnetic interference characteristics of optical fiber sensors to overcome the limitations of traditional electrical torque sensors in measuring tiny torques. The test platform can accurately measure friction torque, which is particularly suitable for measuring tiny friction torques.

[0039] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A bearing micro-friction torque test platform based on fiber Bragg grating, comprising a test bench, a drive shaft mounted on the test bench and a friction torque test device, wherein the inner ring of the bearing to be tested is mounted on the drive shaft, and the friction torque test device is closely fitted with the outer ring of the bearing to be tested for measurement, characterized in that: The friction torque testing device includes a shell, a connecting beam, a fiber grating sensor and a lever, wherein the two ends of the connecting beam are respectively fixed on the shell, and the lever is vertically fixedly connected to the midpoint of the connecting beam to form a "T"-shaped structure, and the "T"-shaped structure is located on a plane perpendicular to the drive shaft and aligned with the bearing to be tested, and the fiber grating sensors are symmetrically arranged on the connecting beams on both sides of the lever, and a support rod is hinged on one side of the lever close to the connecting beam, and the other end of the support rod is fixed on the shell, and a suction cup is installed on the other end of the lever, and the suction cup is adsorbed on the outer ring of the bearing during testing.

2. A bearing micro-friction torque test platform based on fiber grating according to claim 1, characterized in that: The hinge point between the support rod and the lever divides the lever into two parts, a long end and a short end. The short end is located at one end close to the connecting beam, and the ratio of the short end to the long end is preferably 1:

5.

3. The fiber grating-based bearing micro-friction torque test platform according to claim 1, characterized in that: The material used for the connecting beam is nylon plastic.

4. The fiber grating-based bearing micro-friction torque test platform according to claim 1, characterized in that: The driving shaft is connected to the motor to drive the inner ring of the bearing to be tested to rotate.

5. The fiber grating-based bearing micro-friction torque test platform according to claim 1, characterized in that: The test bench is also provided with a rib, which is arranged on the opposite side of the suction cup. The rib is in micro-gap contact with the outer ring of the bearing to be tested to prevent the rolling element of the bearing from shifting during rotation.

6. A bearing micro-friction torque test platform based on fiber grating according to claim 5, characterized in that: The contact gap between the rib and the outer ring of the bearing to be tested is 0.01 mm-0.1 mm.

7. The fiber grating-based bearing micro-friction torque test platform according to claim 5, characterized in that: The position of the rib is adjustable to accommodate bearings of different models.

8. The fiber grating-based bearing micro-friction torque test platform according to claim 1, characterized in that: The bearing friction torque measured by the friction torque testing device is: M = ε·A·E·L1; wherein A is the cross-sectional area of ​​the connecting beam, E is the elastic modulus of the connecting beam, and L1 represents the length of the short end of the lever; strain k is the strain sensitivity coefficient of the fiber Bragg grating central wavelength drift, λ0 is the original wavelength of the fiber Bragg grating sensor, and △λ1 is the wavelength change caused by the deformation of the fiber Bragg grating sensor due to force, which is obtained in real time by the signal acquisition instrument.

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