Bearing radial load intelligent test system

Abstract

The invention relates to a bearing radial load intelligent test system, which is characterized in that a bearing to be tested, a sliding block, circular ring force sensors and an annular base form an intelligent bearing system, the radial load of the bearing is decomposed into each circular ring force sensor through the sliding block, and the circular ring force sensors utilize the characteristics of fiber grating sensors to measure the radial load of the bearing. The system has temperature compensation and sensitization effects, can perform real-time, accurate and high-sensitivity distributed monitoring on the radial load of the bearing, has the advantages of electromagnetic interference resistance, small size, good temperature compensation effect, multi-point distributed measurement, real-time online monitoring and the like, and provides powerful support for dynamic radial load monitoring and performance evaluation of the rolling bearing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bearing performance testing, and particularly relates to a bearing radial load intelligent testing system. BACKGROUND

[0002] With the rapid development of industrial technology, the performance requirements of bearings, which are key components of mechanical equipment, are increasing. Bearings are widely used in high-precision mechanical equipment, aerospace, high-speed numerical control machine tools, industrial robots and other application scenarios. In these fields, bearings, as key components that bear loads and transmit motion in mechanical equipment, directly affect the running stability, machining accuracy and service life of the equipment. Therefore, high-precision dynamic load monitoring of bearings to evaluate their performance under different working conditions not only helps to diagnose abnormal load distribution and identify potential fault risks, but also provides effective support for equipment operation optimization, structure design improvement and residual life assessment.

[0003] Traditional bearing radial load testing systems mostly use resistance strain gauges as sensing cores, and their typical structures include rigid bearing seats (for fixing the measured bearings), resistance strain gauges, metal wires connected to the strain gauges (for signal transmission) and external signal conditioning modules. The strain gauges need to be pasted near the bearing outer ring or loading points, and the stress changes are reflected through voltage output during the test. However, this system has the following problems: First, resistance strain gauges are susceptible to electromagnetic interference, and complex cables and signal shielding layers need to be arranged, which affects the accuracy of measurement results. Second, the sensor arrangement is complex, especially when implementing multi-point distributed measurement, the wiring is tedious, which limits the flexibility and expandability of the system. At the same time, the temperature compensation effect of traditional sensors is poor, and temperature changes will affect the measurement accuracy. In addition, the traditional testing system cannot realize real-time online monitoring, it is difficult to respond to load abnormalities in time, and the sensor volume is large, which is not suitable for space-limited application scenarios. SUMMARY

[0004] In view of the defects of the prior art, the present application provides a bearing radial load intelligent testing system, which is built based on fiber Bragg grating sensors, has a simple and compact structure, and has the advantages of good anti-electromagnetic interference and temperature compensation effect, and can realize multi-point distributed measurement and real-time online monitoring.

[0005] To achieve the above purpose, the technical scheme adopted by the present application is:

[0006] The application relates to a bearing radial load intelligent testing system which comprises a bearing to be tested, a plurality of force-sensitive units uniformly distributed along the circumference of the outer ring of the bearing to be tested, and a ring-shaped base for mounting the force-sensitive units, each force-sensitive unit comprising a slider and a circular ring force sensor, the plurality of circular ring force sensors are uniformly distributed in the ring-shaped base, the ring-shaped base is arranged concentrically with the bearing to be tested, each circular ring force sensor is inscribed in the ring-shaped base and connected at the tangent point, four FBG sensors are uniformly arranged on the inner wall of the circular ring force sensor, and the connecting lines of two FBG sensors arranged in the radial direction pass through the center of the ring-shaped base; a slider is arranged between each circular ring force sensor and the outer ring of the bearing to be tested; a circular hole is arranged at the center of the bottom of the circular ring force sensor; a boss is arranged on the top surface of the slider and is in butt joint with the circular hole; the two ends of the slider are respectively attached to the outer ring of the bearing to be tested and the circular ring force sensor for transmitting the radial load; all the FBG sensors are connected in series and connected to a fiber grating demodulator; the system can calculate the size and direction of the total radial load borne by the bearing to be tested by real-time demodulation of the data of each circular ring force sensor, so that the working condition of the bearing can be comprehensively monitored.

[0007] Further, 10 circular ring force sensors are uniformly arranged in the ring-shaped base, 40 FBG sensors in the 10 circular ring force sensors are connected in series through optical fibers and are uniformly connected to one fiber grating demodulator for real-time acquisition of the central wavelength data of all the FBG sensors.

[0008] Further, the bottom of the slider is a smooth arc surface matched with the curved surface of the outer ring of the bearing to be tested, so that lateral slippage in load transmission can be avoided.

[0009] Further, the circular ring force sensor is made of alloy steel.

[0010] Further, the FBG sensors are fixed on the inner wall of the circular ring force sensor in a pasting mode.

[0011] Further, the boss is a cylindrical boss with a diameter of 2 mm and a hard alloy material, and the boss has the same size as the circular hole at the bottom of the circular ring force sensor.

[0012] Further, the ring-shaped base and the circular ring force sensor are provided with corresponding threaded holes at the tangent point and are connected through screws.

[0013] Further, the system receives the wavelength data of the FBG sensors connected in series through the fiber grating demodulator, and performs stress calculation, specifically as follows: The total wavelength variation of the four measuring points in a single circular ring force sensor is 4Delta Lambda 2, and Delta Lambda 2 is the wavelength variation measured at the topmost measuring point; the wavelength variation is converted into strain, and the strain of the circular ring is obtained: K is the strain sensitivity coefficient of the central wavelength drift of the fiber grating, and lambda 0 is the original wavelength of the fiber grating. According to Hooke's law, the circumferential stress of the inner edge of the circular ring is: sigma = epsilon * A * E; wherein A is the cross-sectional area of the FBG sensor, and E is the elastic modulus of the circular ring; Combined with the circumferential stress function of the inner side of the circular ring, the loading force F applied to the circular ring force sensor is: Wherein a is the inner diameter of the circular ring, t is the thickness of the circular ring, and theta is the polar angle; According to the calculation formula of the loading force F, the load F of each circular ring force sensor is independently calculated i ; Then through the superposition formula The radial load of the whole bearing to be measured is obtained, theta i is the position angle corresponding to each circular ring sensor, and n is the number of circular ring force sensors.

[0014] Beneficial effects:

[0015] The intelligent bearing radial load test system is built based on the fiber grating force sensor, the bearing to be measured, the slider, the fiber grating force sensor and the annular base are combined into an intelligent bearing system through ingenious structure design, and a set of intelligent test system capable of real-time, accurate and high-sensitivity distributed monitoring of bearing radial load is successfully constructed, which provides strong support for dynamic radial load monitoring and performance evaluation of rolling bearings, the fiber grating force sensor can realize temperature self-compensation and sensitivity enhancement effect, the radial load of the bearing to be measured can be obtained through stress calculation, and there is no electromagnetic interference problem, so that the test system has the advantages of anti-electromagnetic interference, small volume, good temperature compensation effect, multi-point distributed measurement and real-time online monitoring, and can meet the needs of modern bearing load detection. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is the overall structure schematic diagram of the intelligent bearing radial load test system of the application;

[0017] Figure 2 It is the structure schematic diagram of the circular ring force sensor;

[0018] Figure 3 It is the three-dimensional structure schematic diagram of the circular ring;

[0019] Figure 4 It is the three-dimensional structure schematic diagram of the slider;

[0020] Figure 5 It is the three-dimensional structure schematic diagram of the annular base.

[0021] The drawing label: 1 bearing to be measured, 2 circular ring force sensor, 3 slider, 4 annular base, 5 circular ring, 6 circular hole, 7 boss. DETAILED DESCRIPTION

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] In order to describe the present invention more clearly, the directional terms involved in the present invention are defined as follows: in this system, for the same component, the part close to the center of the system is called the bottom, and the part away from the center of the system is called the top. For example, for the annular force sensor 2, the part in contact with the annular base 4 is the top, and the part opposite to it is the bottom. For the slider 3, the side in contact with the annular force sensor 2 is the top, and the side in contact with the outer ring of the bearing 1 to be tested is the bottom.

[0024] like Figures 1-5 As shown, an intelligent bearing radial load testing system has an overall structure comprising: a bearing to be tested 1, a plurality of force-sensitive units uniformly distributed along the circumference of the outer ring of the bearing to be tested 1, and an annular base 4 for mounting the force-sensitive units, wherein each force-sensitive unit comprises a slider 3 and an annular force sensor 2, the bearing to be tested 1 is located at the center of the system, the annular base 4 is concentrically arranged with the bearing to be tested 1, each annular force sensor 2 comprises a ring 5 and four fiber Bragg grating (FBG) sensors uniformly distributed on the inner wall of the ring, all FBG sensors are connected in series and connected to the same fiber Bragg grating demodulator, the system demodulates the data of each annular force sensor 2 in real time according to the wavelength change measured by the fiber Bragg grating demodulator, and can accurately calculate the magnitude and direction of the total radial load on the bearing to be tested 1, thereby realizing comprehensive monitoring of the bearing working condition.

[0025] Multiple annular force sensors 2 are evenly distributed along the circumference of the annular base 4. The annular force sensors 2 are tangent to the inner wall of the annular base 4. Multiple threaded holes are opened in the circumference of the annular base 4. The top of the annular force sensor 2 is also provided with a threaded hole corresponding to the annular base 4. Each annular force sensor 2 is connected to the annular base 4 by screwing in a screw. At the same time, the threaded hole on the top of the annular force sensor 2 should be set directly opposite one of the FBG sensors to ensure that after the annular force sensor 2 is installed, the connection line of the two diametrically arranged FBG sensors on its inner wall passes through the center of the test system.

[0026] Each annular force sensor 2 is connected to the outer ring of the bearing 1 to be tested through a slider 3. The bottom of the slider 3, that is, the area in contact with the bearing 1 to be tested, is designed as a precise arc-shaped concave surface to fit the surface of the outer ring of the bearing 1 to be tested, thereby ensuring stable contact and uniform force; the top surface of the slider 3 is designed as an arc surface that fits the bottom of the annular force sensor 2. At the same time, a circular hole 6 is provided at the bottom center of each annular force sensor 2 (that is, the position opposite to the threaded hole), and a boss 7 matching the circular hole 6 is provided on the top of the slider 3. The boss 7 and the circular hole 6 cooperate to achieve docking between the slider 3 and the annular force sensor 2.

[0027] In a specific embodiment, the boss 7 is 2 mm in diameter and made of cemented carbide, and the boss 7 and the circular hole 6 are substantially the same size and are in clearance fit with a fit tolerance of H7 / g6. The boss 7 and the circular hole 6 are in abutment, so that the radial force of the bearing 1 to be measured can be concentrated and transmitted to the measuring point of the circular ring force sensor 2. The design of the sliding block 3 ensures low friction during load transmission, so that the radial force of the bearing 1 to be measured can be accurately transmitted to the corresponding circular ring force sensor 2 when the bearing 1 to be measured is running, and the tangential frictional force interference is effectively isolated.

[0028] The structure of a single circular ring force sensor 2 is shown in Figure 2 The circular ring 5 and the four built-in fiber Bragg grating (FBG) sensors and signal extraction optical fibers are composed of four FBG sensors, which are accurately pasted at the positions of 0° (point A, FBG1), 90° (point B, FBG2), 180° (point C, FBG3) and 270° (point D, FBG4) on the inner wall of the circular ring, respectively. The four FBG sensors are connected in series through optical fibers, and the radial pressure is along the AC direction. When the circular ring force sensor 2 is subjected to external temperature and radial pressure of the same size, it is assumed that the temperature rise of each part inside the circular ring 5 is equal. According to the edge stress function of the inside of the circular ring 5, the relationship between the wavelength change amount caused by temperature and the total wavelength change amount of the measuring point can be obtained by calculation, without the need for a temperature compensation module to achieve temperature self-compensation. By converting the wavelength change amount of the four measuring points into a multiple of the wavelength change amount of a single measuring point, the purpose of sensitivity enhancement is achieved. The specific temperature compensation and sensitivity enhancement calculation process is as follows.

[0029] Temperature compensation: it is assumed that the wavelength change amount caused by uniform temperature rise is Δλ1, the wavelength change amount at A and C caused by force is Δλ2, and the wavelength change amount at B and D caused by force is Δλ3; the total change amount x measured at A and C is Δλ1+Δλ2; the total change amount y measured at B and D is Δλ1+Δλ3; according to theoretical analysis, the force at A and C is equal in size and opposite in direction to that at B and D, so the relationship between Δλ3 and Δλ2 is Δλ3=-Δλ2; thus we have:

[0030]

[0031] By calculating by the formula (1), the wavelength drift Δλ1 caused by temperature change can be accurately separated, so as to eliminate the interference of temperature on load measurement and achieve temperature self-compensation.

[0032] Sensitivity calculation: in order to improve the signal-to-noise ratio and measurement sensitivity, the system uses differential operation to amplify the effective load signal. The system uses Δλ A +Δλ C -(Δλ B +Δλ D) and the wavelength variation measured at the measuring point, the following equation can be obtained:

[0033] This result not only completely eliminates the temperature term Δλ1, but also converts the wavelength variations of the four measuring points into four times the wavelength variation measured at point A by a single FBG sensor, achieving the effect of sensitization.

[0034] On the basis of the above temperature compensation and sensitization calculation, the wavelength variation is converted into strain, combined with the circumferential stress function of the inner side of the ring, and the loading force F is back calculated to realize quantitative calculation of the radial load. The specific process is as follows.

[0035] Stress calculation: strain of the ring force sensor 2:

[0036] In the present test system, the strain is the strain caused by the radial load borne by the bearing 1 to be tested, wherein k is the strain sensitivity coefficient of the central wavelength drift of the fiber grating, and λ0 is the original wavelength of the fiber grating.

[0037] According to the strain and Hooke's law, the circumferential stress of the inner edge of the ring is calculated: σ=ε·A·E (4)

[0038] Wherein A is the cross-sectional area of the fiber grating sensor, and E is the elastic modulus of the ring structure.

[0039] Assuming that the inner and outer diameters of the ring 5 are a and b respectively, the thickness is t, the loading force applied on the ring force sensor 2 is F, r is the polar radius, and θ is the polar angle, then the circumferential stress function of the inner edge of the ring 5 is:

[0040] From the above stress function and the calculated circumferential stress σ of the inner side of the ring 5, the loading force F applied on the ring force sensor 2 can be back calculated:

[0041] The loading force F borne by a single ring force sensor 2 can be calculated by the above formula (5). In the test system of the present embodiment, 10 ring force sensors 2 are provided, and 40 FBG sensors in the 10 sensors are connected in series by an optical fiber and connected to a fiber grating demodulator for real-time acquisition of the central wavelength data of all FBG sensors.

[0042] The radial forces borne by the bearing 1 to be tested at different positions can be respectively obtained by the above formula (5), which are F1, F2, F3, F4, F5, F6, F7, F8, F9, F 10The total radial force is:

[0043] Wherein θ i is the position angle corresponding to each toroidal force sensor 2.

[0044] If the number of toroidal force sensors is n, then

[0045] When testing using the intelligent bearing radial load test system of the present application, a plurality of toroidal force sensors 2 are prepared, then the plurality of toroidal force sensors 2 are installed on the annular base 4 through screws, and the positions of the FBG sensors are ensured to be correct, the boss 7 on the slider 3 is connected with the circular hole 6 at the bottom of the toroidal force sensor 2, the slider 3 is installed in place, then the bearing to be tested 1 is installed, the outer ring of the bearing to be tested 1 is attached to the circular arc-shaped concave surface at the bottom of the slider 3; the FBG sensors of all the toroidal force sensors 2 are connected in series through optical fibers and then connected to a fiber Bragg grating demodulator, then the entire intelligent test system is installed on a bearing seat, when the bearing to be tested 1 is running, the radial load on its outer ring is decomposed and transmitted to the corresponding toroidal force sensor 2 through the slider 3 in each force-sensitive unit, the wavelength data of the FBG sensors connected in series are received by the fiber Bragg grating demodulator, then the data of each toroidal force sensor 2 is demodulated in real time, combined with temperature compensation and sensitization algorithms, and using vector synthesis algorithm, the total radial load on the bearing to be tested 1 can be accurately calculated in size and direction, so as to realize comprehensive monitoring of the working condition of the bearing.

[0046] In summary, through ingenious structural design, the toroidal force sensor 2 is integrated with the bearing to be tested 1 through the slider 3 and the annular base 4, four FBG sensors are arranged inside the toroidal force sensor 2, which has temperature compensation and sensitization characteristics, combined with specific temperature compensation, sensitization calculation and stress settlement process, a set of intelligent test system capable of real-time, accurate and high-sensitivity distributed monitoring of bearing radial load is successfully constructed, which provides strong support for dynamic radial load monitoring and performance evaluation of rolling bearings, and has advantages of anti-electromagnetic interference, small size, good temperature compensation effect, multi-point distributed measurement and real-time online monitoring, etc., which can meet the needs of modern bearing load detection.

[0047] The above merely describes preferred embodiments of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed with the preferred embodiments as above, it is not intended to limit the present application. Any person skilled in the art, without departing from the technical solution of the present application, can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, without departing from the technical solution of the present application, still belongs to the scope of the technical solution of the present application.

Claims

1. An intelligent bearing radial load testing system, comprising a bearing to be tested, a plurality of force-sensitive units uniformly distributed along the circumference of the outer ring of the bearing to be tested, and an annular base for mounting the force-sensitive units, characterized in that: Each force-sensitive unit includes a slider and a circular force sensor. Multiple circular force sensors are evenly distributed in the circular base. The circular base is arranged concentrically with the bearing to be tested. Each circular force sensor is inscribed in the circular base and connected at the tangent point. Four FBG sensors are evenly distributed on the inner wall of the circular force sensor, and the connection line of two of the diametrically arranged FBG sensors passes through the center of the circular base. A slider is set between each circular force sensor and the outer ring of the bearing to be tested. A circular hole is provided at the bottom center of the circular force sensor, and a boss is provided on the top surface of the slider to dock with the circular hole. The two ends of the slider are respectively fitted with the outer ring of the bearing to be tested and the circular force sensor to transmit radial load. All FBG sensors are connected in series and connected to the fiber optic Bragg grating demodulator. The system can calculate the magnitude and direction of the total radial load on the bearing to be tested by real-time demodulation of the data of each circular force sensor, thereby realizing comprehensive monitoring of the bearing working condition.

2. The intelligent bearing radial load testing system according to claim 1, characterized in that: Ten circular force sensors are evenly arranged in a ring base. A total of 40 FBG sensors in the 10 circular force sensors are connected in series via optical fibers and uniformly connected to a fiber Bragg grating demodulator for real-time acquisition of central wavelength data of all FBG sensors.

3. The intelligent bearing radial load testing system according to claim 1, characterized in that: The bottom of the slider is a smooth arc surface that fits the curved surface of the outer ring of the bearing to be tested, which can avoid lateral slippage during load transmission.

4. The intelligent bearing radial load testing system according to claim 1, characterized in that: The annular force sensor is made of alloy steel.

5. The intelligent bearing radial load testing system according to claim 1, characterized in that: The FBG sensor is fixed to the inner wall of the annular force sensor by gluing.

6. The intelligent bearing radial load testing system according to claim 1, characterized in that: The boss is a cylindrical boss with a diameter of 2 mm and a material of cemented carbide. The boss has the same size as the circular hole at the bottom of the annular force sensor.

7. The intelligent bearing radial load testing system according to claim 1, characterized in that: The annular base and the annular force sensor are provided with corresponding threaded holes at the tangent points, and the two are connected by screws.

8. The intelligent bearing radial load testing system according to claim 1, characterized in that: The system receives the wavelength data of the serially connected FBG sensors through the fiber Bragg grating interrogator and performs stress calculation, specifically: The total wavelength change of the four measuring points in a single ring force sensor is 4Δλ2, where Δλ2 is the wavelength change measured at the topmost measuring point; Converting the wavelength change into strain, we can get the strain of the ring: k is the strain sensitivity coefficient of the fiber Bragg grating center wavelength drift, λ0 is the original wavelength of the fiber Bragg grating; According to Hooke's law, the circumferential stress at the inner edge of the ring is: σ = ε·A·E; where A is the cross-sectional area of ​​the FBG sensor and E is the elastic modulus of the ring; Combined with the circumferential stress function on the inner side of the ring, the loading force F applied to the ring force sensor can be obtained as: Where a is the inner diameter of the ring, t is the thickness of the ring, and θ is the polar angle; According to the calculation formula of loading force F, the load F of each ring force sensor is calculated independently i ; Then by superposition formula Get the radial load of the bearing to be tested, θ i is the position angle corresponding to each circular sensor, and n is the number of circular force sensors.

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