Device and method for monitoring dynamic load of rolling bearing in real time based on optical fiber sensing

Abstract

The invention relates to a rolling bearing dynamic load real-time monitoring device and method based on optical fiber sensing, the monitoring device comprises an inner lantern ring, an outer lantern ring, a connecting beam and an optical fiber Bragg grating sensor, the inner lantern ring is installed on an outer ring of a rolling bearing, the connecting beam is arranged between the inner lantern ring and the outer lantern ring, and the optical fiber Bragg grating sensor is arranged on the connecting beam; the device can measure the axial load and the radial load of the rolling bearing in real time, and has the advantages of high sensitivity, electromagnetic interference resistance, long service life, high monitoring efficiency, strong distributed sensing capability and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of bearing measurement, and in particular to a device and method for real-time monitoring of dynamic load of a rolling bearing based on optical fiber sensing. Background Art

[0002] With the rapid development of industrial technology, mechanical equipment has increasingly higher performance requirements for key components - bearings. As a key component in mechanical equipment that bears loads and transmits motion, the dynamic load bearing capacity of bearings is directly related to the operating stability and service life of the equipment. Therefore, dynamic load testing of bearings to evaluate their performance under different working conditions is of great significance to ensure the safe operation of equipment and improve equipment efficiency.

[0003] By measuring the dynamic load of rolling bearings in real time and taking compensation measures in time, the rotation accuracy and stiffness of the bearings can be effectively improved, the vibration and noise caused by excessive clearance can be reduced, the service life of the bearings can be extended, and the wear generated during operation can be compensated. It can be seen that real-time monitoring of the dynamic load of bearings is of great significance for ensuring the stable operation of equipment, extending the service life of bearings, and improving production efficiency and safety.

[0004] Although the bearing dynamic load monitoring device based on electrical sensors is relatively mature and has a certain degree of sensitivity, it is susceptible to electromagnetic interference and environmental influences such as temperature, which can easily lead to measurement errors. It also requires regular calibration and has installation restrictions. Summary of the invention

[0005] In view of the problems that electrical sensors are easily affected by environmental interference and need regular calibration when monitoring the dynamic load of rolling bearings, the present invention proposes a real-time monitoring device and method for the dynamic load of rolling bearings based on optical fiber sensing, which can complete the real-time measurement of the axial load and radial load on the rolling bearing, and has the advantages of high sensitivity, resistance to electromagnetic interference, long service life, high monitoring efficiency, and strong distributed sensing capability.

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

[0007] A real-time monitoring device for dynamic load of rolling bearing based on optical fiber sensing comprises a rolling bearing, an inner sleeve ring, an outer sleeve ring, a connecting beam, and an optical fiber Bragg grating sensor. The rolling bearing is mounted on a rotating shaft, the inner sleeve ring is mounted on the outer ring of the bearing in an interference fit manner, the outer sleeve ring is concentrically arranged with the inner sleeve ring, a plurality of connecting beams uniformly distributed in the circumferential direction and extending in the radial direction are connected between the outer sleeve ring and the inner sleeve ring, the connecting beams are uniform cross-section beams with a square cross-section, and optical fiber Bragg grating sensors are fixed on four side surfaces at the middle section of each connecting beam.

[0008] Furthermore, the side surface of the connecting beam is parallel or perpendicular to the end surface of the bearing.

[0009] Furthermore, radial distances between the fiber Bragg grating sensors on different connecting beams and the central axis of the bearing are the same or different.

[0010] Furthermore, the connecting beam and the inner ring are an integral structure, and the connecting beam is rigidly connected to the outer side surface of the inner ring.

[0011] Furthermore, a slot is formed on the outer collar, and the connecting beam is fixed to the outer collar through the slot.

[0012] Furthermore, the inner ring and the outer ring are both made of aluminum alloy.

[0013] Furthermore, the number of the connecting beams is six.

[0014] Furthermore, the widths of the inner ring and the outer ring are both greater than the width of the connecting beam and smaller than the width of the bearing outer ring.

[0015] A real-time monitoring method for dynamic load of rolling bearing based on optical fiber sensing, using the above monitoring device to monitor the rolling bearing, comprises the following steps:

[0016] (1) First install the rolling bearing on the rotating shaft, then install the inner ring of the monitoring device on the outer ring of the rolling bearing, and then insert the end of the connecting beam into the slot on the outer ring to fix it;

[0017] (2) Determine the Young's modulus of elasticity of the connecting beam material, the initial center wavelength of the fiber Bragg grating sensor, and the cross-sectional area size parameters of the connecting beam;

[0018] (3) When an axial load and a radial load are applied to the rolling bearing, the inner ring installed on the outer ring of the rolling bearing undergoes micro-motion under the action of the axial load and the radial load. During this process, the connecting beam undergoes elastic deformation under the influence of the external load, causing the central wavelength of the fiber Bragg grating sensor on the connecting beam to change;

[0019] (4) Based on the measured wavelength change of the fiber Bragg grating sensor on the connecting beam, the fiber Bragg grating sensing principle and Hooke's law, the axial load and radial load on a single connecting beam are first calculated, and then the axial load and radial load on the rolling bearing are calculated based on the number of connecting beams between the outer ring and the inner ring.

[0020] When the number of connecting beams between the inner ring and the outer ring is n, and the distribution position of the fiber Bragg grating sensors on each connecting beam is the same, the axial load on the rolling bearing is: F A =n·F a， Among them, F ais the axial load on a single connecting beam; the radial load on the rolling bearing is: where F i For the radial load on each connecting beam, is the position angle corresponding to each connecting beam.

[0021] Beneficial effects:

[0022] The real-time monitoring device for dynamic load of rolling bearings based on optical fiber sensing of the present invention has a simple structure and is easy to use. It can monitor the load of rolling bearings in real time and has the advantages of high sensitivity, resistance to electromagnetic interference, long service life, high monitoring efficiency, strong distributed sensing capability, etc. It can well make up for the shortcomings of electrical sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 : A schematic diagram of the structure of a monitoring device in an embodiment of the present invention, Figure 1 (A) and Figure 1 (B) Schematic diagrams at different angles;

[0024] Figure 2 : A schematic structural diagram of an outer sleeve ring in an embodiment of the present invention;

[0025] Figure 3 : A schematic diagram of the structure of the inner and outer rings and the connecting beam in an embodiment of the present invention;

[0026] Figure 4 : Schematic diagram of the distribution of FBG on the connecting beam in an embodiment of the present invention.

[0027] Reference numerals: 1 inner ring, 2 connecting beam, 3 slot, 4 outer ring, 5 fiber Bragg grating (FBG) sensor. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the illustrations provided in the present embodiment are only schematic illustrations of the basic concept of the present invention, and the drawings only show components related to the present invention rather than the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed at will, and the component layout may also be more complicated.

[0029] like Figure 1-4As shown, a real-time monitoring device for dynamic load of rolling bearing based on optical fiber sensing includes a rolling bearing, an inner ring 1, an outer ring 4, a fiber Bragg grating (FBG) sensor 5, and a connecting beam 2, wherein the rolling bearing is installed on the rotating shaft through the inner ring of the bearing, the inner ring 1 is installed on the outer ring of the bearing, and the inner ring 1 forms an interference fit with the outer ring of the bearing, the outer ring 4 is concentrically arranged with the inner ring 1, and a plurality of connecting beams 2 uniformly distributed in the circumferential direction and extending in the radial direction are connected between the outer ring 4 and the inner ring 1, the connecting beam 2 is usually an integral structure with the inner ring 1, formed by processing, and the two are rigidly connected, the outer ring 4 is provided with a slot 3, and the connecting beam 2 is fixed to the outer ring 4 through the slot 3.

[0030] The connecting beam 2 is a square cross-section beam with a uniform cross-section. Fiber Bragg grating (FBG) sensors 5 are distributed on the four sides of each connecting beam 2. Each fiber Bragg grating (FBG) sensor 5 is distributed in the middle of the connecting beam 2. The distances between each fiber Bragg grating (FBG) sensor 5 and the central axis of the rolling bearing are equal or unequal, and one of the side surfaces of the connecting beam 2 is parallel to the end surface of the bearing. Usually, the connecting beam 2 uses a square cross-section beam with a uniform cross-section, and each fiber Bragg grating (FBG) sensor 5 is distributed at the same radial position, which can make the load calculation more convenient.

[0031] The widths of the inner ring 1 and the outer ring 4 are both greater than the width of the connecting beam 2 and smaller than the width of the bearing outer ring.

[0032] The density and elastic modulus of the materials used for the inner ring 1, the outer ring 4 and the connecting beam 2 should be as small as possible, and materials such as aluminum alloy can be used to reduce their own weight as much as possible.

[0033] When the above monitoring device is used to measure the dynamic load of the rolling bearing, the inner ring 1 and the outer ring 4 are first installed on the rolling bearing, and then the relevant parameters required for the measurement are determined, including the elastic modulus of the material of the connecting beam 2, the cross-sectional area, size, and length of the connecting beam 2, etc., and then the axial load and radial load are applied to the end face of the outer ring of the rolling bearing and the surface of the inner ring of the bearing respectively. The inner ring 1 undergoes micro-motion under the action of the axial load and the radial load, and the connecting beam 2 undergoes elastic deformation under the influence of the external load during this process, resulting in a change in the central wavelength of the fiber Bragg grating (FBG) sensor 5 on the connecting beam 2; according to the measured wavelength change of the fiber Bragg grating (FBG) sensor 5 on the connecting beam 2, the fiber grating sensing principle, and Hooke's law, the magnitudes Fa and Fr of the axial load and radial load on the single connecting beam 2 are first calculated, and then the axial load and radial load on the rolling bearing are calculated according to the number of connecting beams between the outer ring 4 and the inner ring 1.

[0034] Example 1

[0035] In this embodiment, the connecting beam uses a square cross-section beam with a uniform cross-section. The number of connecting beams is 6. FBG sensors are respectively attached to the four sides of each connecting beam, wherein a pair of FBG sensors on two mutually parallel sides are used to measure radial loads, and another pair of FBG sensors on two mutually parallel sides are used to measure axial loads, and each FBG sensor is arranged at the same radial position. The real-time monitoring method for dynamic load of rolling bearings using the monitoring device includes the following steps:

[0036] (1) First install the rolling bearing on the rotating shaft, then install the inner ring of the monitoring device on the outer ring of the rolling bearing, and then insert the end of the connecting beam into the slot on the outer ring to fix it.

[0037] (2) Determine the Young's elastic modulus E of the connecting beam material, the initial central wavelength λ0 of the fiber Bragg grating (FBG) sensor, the cross-sectional area A of the connecting beam, the length L of the connecting beam, and the cross-sectional width b.

[0038] (3) An axial load and a radial load are applied to the end face of the outer ring and the surface of the inner ring of the rolling bearing respectively through an axial loading device and a radial loading device. The ring of the outer ring of the rolling bearing undergoes micro-motion under the action of the axial load and the radial load. During this process, the connecting beam undergoes elastic deformation under the influence of the external load, causing the central wavelength of the fiber Bragg grating (FBG) sensor on the connecting beam to change.

[0039] (4) According to the measured wavelength change of the fiber Bragg grating (FBG) sensor on the connecting beam, the fiber Bragg grating sensing principle and Hooke's law, the magnitudes of the axial load and radial load Fa and Fr on a single connecting beam are calculated. According to the number of connecting beams between the outer ring and the inner ring, the axial load and radial load on the rolling bearing are calculated. The specific process is as follows:

[0040] During the measurement, a signal acquisition instrument is used to obtain the average value λ of the wavelength signal of the fiber Bragg grating (FBG) sensor evenly distributed on the side of the connecting beam in real time. B1 ; According to the fiber Bragg grating sensing principle, the bending strain of the connecting beam caused by the axial load is:

[0041] ε a =(λ B1 -λ0) / (λ B1 ·K ε ); (1)

[0042] Where λ0 is the initial center wavelength of the fiber Bragg grating (FBG) sensor, K ε is the strain sensitivity coefficient of fiber Bragg grating center wavelength drift;

[0043] The bending stress of the cross section at the centroid of the connecting beam is calculated based on the strain and Hooke's law:

[0044] σ=E·ε a (2)

[0045] E is Young's elastic modulus of the connecting beam material, ε a is the bending strain of the connecting beam caused by the axial load.

[0046] According to the bending strain formula of material mechanics, we can get:

[0047] σ=M·y / I (3)

[0048] Where M is the bending moment, y is the distance from a micro area on the cross section to the neutral axis of the beam. The micro area refers to a very small area dA taken on the cross section of the connecting beam for stress and strain analysis. I is the moment of inertia of the cross section to the neutral axis of the beam, I = b 4 / 12, b is the cross-sectional width of the connecting beam, and the bending moment M can be calculated by formula (3).

[0049] Since the bending of the beam is caused by the external load, the moment equilibrium equation can be obtained:

[0050] M=Fa·L / 2 (4)

[0051] L is the length of the connecting beam, Fa is the axial load on a single connecting beam, and the axial load on a single connecting beam can be calculated according to formula (4).

[0052] Therefore, the axial load on the rolling bearing is:

[0053] F A =n·Fa (5)

[0054] Wherein n is the number of connecting beams used, and in this embodiment n=6.

[0055] The strain of the connecting beam caused by the radial load is:

[0056] ε bi =(λ Bi -λ0) / (λ Bi ·K ε ) (6)

[0057] where ε bi is the strain of each connecting beam under radial load, λ Bi is the average value of the wavelength change signal of the fiber Bragg grating (FBG) sensor on the two parallel sides of the connecting beam acquired in real time by the signal acquisition instrument, i = 1, 2, 3, 4, 5, 6, K ε is the strain sensitivity coefficient of fiber Bragg grating center wavelength drift.

[0058] According to Hooke's law, the stress on each connecting beam can be obtained as

[0059] σ i =E·ε bi (7)

[0060] The external force on each beam can be obtained from the cross-sectional area A2 of the connecting beam:

[0061] F i =σ i ·A2 (8)

[0062] In the above, i = 1, 2, 3, 4, 5, 6. From formula (8), it can be obtained that the radial forces at different positions of the rolling bearing are F1, F2, F3, F4, F5, F6 respectively; therefore, the total radial force of the rolling bearing, i.e. the radial load, is:

[0063]

[0064] in is the position angle corresponding to each connecting beam, In the illustrated embodiment, a total of 6 connecting beams are provided, and the position angles corresponding to each connecting beam are 0°, 60°, 120°, 180°, 240°, and 300°, respectively.

[0065] It can be seen that the use of the monitoring device described in the present invention can conveniently perform real-time monitoring and calculation of the dynamic load of the rolling bearing. This monitoring device and method have obvious advantages in sensitivity, anti-interference, service life, distributed sensing capability, monitoring efficiency, etc., and provide strong support for the dynamic load monitoring and performance evaluation of rolling bearings.

[0066] 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 real-time monitoring device for dynamic load of rolling bearing based on optical fiber sensing, characterized in that: The invention comprises a rolling bearing, an inner ring, an outer ring, a connecting beam, and a fiber Bragg grating sensor. The rolling bearing is mounted on a rotating shaft. The inner ring is mounted on the outer ring of the bearing in an interference fit manner. The outer ring is concentrically arranged with the inner ring. A plurality of connecting beams uniformly distributed in the circumferential direction and extending in the radial direction are connected between the outer ring and the inner ring. The connecting beams are square beams with uniform cross-sections. Fiber Bragg grating sensors are fixed on four side surfaces at the middle section of each connecting beam.

2. The real-time monitoring device for dynamic load of rolling bearing based on optical fiber sensing according to claim 1 is characterized in that: The side surface of the connecting beam is parallel or perpendicular to the bearing end surface.

3. The real-time monitoring device for dynamic load of rolling bearing based on optical fiber sensing according to claim 1 is characterized in that: The radial distances between the fiber Bragg grating sensors on different connecting beams and the central axis of the bearing are the same or different.

4. The real-time monitoring device for dynamic load of rolling bearing based on optical fiber sensing according to claim 1 is characterized in that: The connecting beam and the inner sleeve ring are an integrated structure, and the connecting beam is rigidly connected to the outer side surface of the inner sleeve ring.

5. The real-time monitoring device for dynamic load of rolling bearing based on optical fiber sensing according to claim 1 is characterized in that: The outer sleeve is provided with a slotted hole, and the connecting beam is fixed to the outer sleeve through the slotted hole.

6. The real-time monitoring device for dynamic load of rolling bearing based on optical fiber sensing according to claim 1, characterized in that: The inner ring and the outer ring are both made of aluminum alloy.

7. The real-time monitoring device for dynamic load of rolling bearing based on optical fiber sensing according to claim 1 is characterized in that: The number of the connecting beams is six.

8. The real-time monitoring device for dynamic load of rolling bearing based on optical fiber sensing according to claim 1, characterized in that: The widths of the inner ring and the outer ring are both greater than the width of the connecting beam and smaller than the width of the bearing outer ring.

9. A real-time monitoring method for dynamic load of rolling bearing based on optical fiber sensing, characterized in that: The monitoring method uses the monitoring device according to any one of claims 1 to 8 to monitor the rolling bearing, comprising the following steps: (1) First install the rolling bearing on the rotating shaft, then install the inner ring of the monitoring device on the outer ring of the rolling bearing, and then insert the end of the connecting beam into the slot on the outer ring to fix it; (2) Determine the Young's modulus of elasticity of the connecting beam material, the initial center wavelength of the fiber Bragg grating sensor, and the cross-sectional area size parameters of the connecting beam; (3) When an axial load and a radial load are applied to the rolling bearing, the inner ring installed on the outer ring of the rolling bearing undergoes micro-motion under the action of the axial load and the radial load. During this process, the connecting beam undergoes elastic deformation under the influence of the external load, causing the central wavelength of the fiber Bragg grating sensor on the connecting beam to change; (4) Based on the measured wavelength change of the fiber Bragg grating sensor on the connecting beam, the fiber Bragg grating sensing principle and Hooke's law, the axial load and radial load on a single connecting beam are first calculated, and then the axial load and radial load on the rolling bearing are calculated based on the number of connecting beams between the outer ring and the inner ring.

10. A method for real-time monitoring of dynamic load of rolling bearing based on optical fiber sensing according to claim 9, characterized in that: When the number of connecting beams between the inner ring and the outer ring is n, and the distribution position of the fiber Bragg grating sensors on each connecting beam is the same, the axial load on the rolling bearing is: F A =n·F a， Among them, F a is the axial load borne by a single connecting beam; The radial load on the rolling bearing is: Among them, F i For the radial load on each connecting beam, is the position angle corresponding to each connecting beam.

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