Anchor cable sensor based on optical fiber MEMS technology

Abstract

The utility model relates to an anchor cable sensor based on the optical fiber MEMS technology, which comprises an annular shell internally provided with a stress ring, the stress ring comprises two large-diameter cylindrical connecting bodies and a small-diameter cylindrical main body, the cylindrical main body is provided with an arc-shaped groove, a sealing ring is clamped between the cylindrical connecting bodies and the annular shell, and the annular shell is provided with an annular groove. The cylindrical body is provided with a plurality of MEMS strain gauges in a circumferential array. After initial calibration, the anchor cable sensor can analyze the magnitude of light waves returned by a plurality of strain gauges through a demodulator, so that stress data in all directions are calculated, actual stress and unbalance loading conditions on the anchor cable are calculated through software, reliable data basis is provided for a monitoring system, and the monitoring accuracy is improved. Based on the advantages of high resolution and high precision of the optical fiber MEMS, tiny displacement can be monitored, reliable data support can be provided, in addition, sealing rings are installed between the two ends of the stress ring and the annular shell, and normal work of the sensor in severe environments such as the field and the underground is guaranteed.

Description

TECHNICAL FIELD

[0001] The utility model relates to optical sensing technical field especially is a kind of anchor cable sensor based on optical fiber MEMS technology. BACKGROUND

[0002] Anchor cable sensor is a kind of device for measuring anchor cable stress variation between anchor cable tray and fastening nut, current anchor cable sensor mainly has strain anchor cable sensor, vibrating-wire anchor cable sensor, fiber grating anchor cable sensor, wherein, strain anchor cable sensor is based on strain effect principle, when anchor cable is deformed by external force, strain gauge pasted on the surface of anchor cable will also be deformed, thereby leading to the resistance value of strain gauge changes, by measuring the resistance value of strain gauge changes, the strain of anchor cable can be calculated, and then the force condition of anchor cable is obtained;Vibrating-wire anchor cable sensor utilizes the corresponding relationship between vibrating-wire vibration frequency and tension, when anchor cable force changes, the tension of sensor inner vibrating-wire will change, thereby making the vibration frequency of vibrating-wire change, by measuring the vibration frequency of vibrating-wire, the force of anchor cable can be determined;Fiber grating anchor cable sensor is based on the linear relationship between fiber grating reflection wavelength and strain or temperature, when anchor cable strain or temperature changes, the reflection wavelength of fiber grating will change accordingly, by detecting the reflection wavelength change of fiber grating, the strain and temperature of anchor cable are simultaneously measured.

[0003] However, strain anchor cable sensor is easily influenced by external factors, such as collision, corrosion, etc., since the strain and force of anchor cable are calculated by resistance value change, it needs to be powered to measure, and the precision is low, and the electromagnetic interference resistance is poor. Vibrating-wire anchor cable sensor is installed inside anchor cable, although it can avoid external environmental interference to some extent, it needs to be designed and processed in advance when anchor cable is manufactured, and the flexibility is poor, the electromagnetic interference resistance is weak, and the precision is relatively low. Fiber grating anchor cable sensor signal changes greatly with temperature, and zero drift is serious under long-time monitoring, and rebound process lag is serious, so it is not suitable for long-term observation. Moreover, anchor cable sensor used in slope, dam and coal mine is easily influenced by dust, moisture and temperature, and the sealing property of current various sensors is poor due to structure limitation, and internal sensor device is easily polluted and corroded, and precision decline or even scrap situation occurs. UTILITY MODEL CONTENTS

[0004] Therefore, the technical problem to be solved by the utility model is to overcome the problems of poor sealing property and low measurement precision of existing anchor cable sensor due to its structure.

[0005] To solve the above technical problems, the utility model provides a kind of anchor cable sensor based on optical fiber MEMS technology, which comprises:

[0006] A ring-shaped cover plate is arranged at one end of the ring-shaped shell;

[0007] A stress ring is clamped in the ring-shaped shell, the stress ring comprises a cylindrical main body and two cylindrical connectors, the two cylindrical connectors are arranged at two ends of the cylindrical main body respectively, the diameter of the cylindrical connector is larger than that of the cylindrical main body, a sealing ring is arranged on the outer side of the cylindrical connector, the sealing ring is tightly attached to the inner wall of the ring-shaped shell, one end of the cylindrical connector away from the cylindrical main body is provided with a boss, the boss penetrates the ring-shaped cover plate, an arc-shaped groove is arranged in the middle of the cylindrical main body, and an anchor cable through hole is arranged along the axis of the stress ring.

[0008] The MEMS strain gauge comprises a strain gauge main body, a MEMS chip and a collimator, the strain gauge main body is in a U shape as a whole, horizontal connecting plates are arranged at the outer sides of two ends of the strain gauge main body, the two horizontal connecting plates are connected to two ends of the cylindrical main body of the stress ring respectively, the MEMS chip is attached to the inner side of one end of the strain gauge main body, and an included angle is arranged between the MEMS chip and the horizontal connecting plate, the collimator is arranged on one of the horizontal connecting plates, and the light-emitting side of the collimator penetrates one end of the strain gauge main body and is aligned with the MEMS chip, and a plurality of MEMS strain gauges are arranged along the outer side of the cylindrical main body.

[0009] In an embodiment of the utility model, the MEMS strain gauge further comprises an optical fiber, the collimator is provided with a through hole, one end of the optical fiber is arranged in the through hole, and the other end of the through hole is aligned with the MEMS chip.

[0010] In an embodiment of the utility model, the utility model further comprises a fiber outlet interface, and the fiber outlet interface is connected to the ring-shaped shell.

[0011] In an embodiment of the utility model, a plurality of bolt holes are arranged on the cylindrical connector away from the ring-shaped cover plate, a plurality of through holes are arranged on the ring-shaped shell, and the plurality of through holes correspond to the bolt holes one by one.

[0012] In an embodiment of the utility model, a plurality of L-shaped mounting grooves are arranged at two ends of the cylindrical connector, a pressing block is arranged on the L-shaped mounting groove, and the horizontal connecting plates at two ends of the strain gauge main body are fixed in the L-shaped mounting groove through the pressing block.

[0013] In an embodiment of the utility model, the horizontal connecting plates at two ends of the strain gauge main body are in abutment with one side groove wall of the L-shaped mounting groove.

[0014] In an embodiment of the utility model, the inner side of strain gauge body is further provided with a plurality of arc-shaped notches, and the plurality of arc-shaped notches divide the one end of strain gauge body, on which the MEMS chip is arranged, into a plurality of straight line segments and circular arc segments.

[0015] In an embodiment of the utility model, the strain gauge body is made of 40CrNiMo material.

[0016] In an embodiment of the utility model, the cylindrical connecting body is provided with an annular groove, and the sealing ring is clamped in the annular groove.

[0017] The above technical solution of the utility model has the following advantages compared with the prior art.

[0018] The anchor cable sensor based on the optical fiber MEMS technology evenly installs a plurality of MEMS strain gauges in the circumferential direction of the stress ring, and after initial calibration, the size of the light wave transmitted back by the three strain gauges can be analyzed by a demodulator, the stress data in each direction is calculated, and the actual stress and eccentric load on the anchor cable are calculated by software, so as to provide reliable data basis for the monitoring system, and based on the advantages of high resolution and high precision of the optical fiber MEMS, the micro displacement can be monitored, and reliable data support is provided, and in addition, the sealing ring is installed between the two ends of the stress ring and the annular shell, so that the sensor can work normally in harsh environments such as field and underground. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to make the content of the utility model more easily understood, the utility model will be further described in detail in combination with the drawings according to the specific embodiments of the utility model, wherein

[0020] Figure 1 It is the overall structure schematic view of the anchor cable sensor based on the optical fiber MEMS technology of the utility model;

[0021] Figure 2 It is the overall structure schematic view of the anchor cable sensor based on the optical fiber MEMS technology of the utility model; Figure 1

[0022] It is the overall structure schematic view of the anchor cable sensor based on the optical fiber MEMS technology of the utility model; Figure 3 Figure 1 It is the overall structure schematic view of the anchor cable sensor based on the optical fiber MEMS technology of the utility model;

[0023] Figure 4 Figure 1 It is the installation schematic view of the anchor cable sensor based on the optical fiber MEMS technology of the utility model.

[0024] ​​The description of the drawings is as follows: 1, annular shell; 110, annular cover plate; 120, fiber exit interface; 2, stress ring; 210, cylindrical body; 211, L-shaped mounting groove; 220, cylindrical connecting body; 230, annular groove; 240, boss; 250, arc-shaped groove; 260, anchor cable through hole; 3, MEMS strain gauge; 310, strain gauge body; 311, arc-shaped notch; 320, MEMS chip; 330, collimator; 340, horizontal connecting plate; 4, bolt hole; 5, through hole; 6, pressing block; 7, anchor cable tray; 8, fastening nut; 9, anchor cable; 10, rock mass. DETAILED DESCRIPTION

[0025] The utility model will be further described below in combination with the drawings and specific embodiments, so that the person skilled in the art can better understand the utility model and can be implemented, but the embodiment is not as the limitation of the utility model.

[0026] Embodiment 1, refer to Figures 1 to 4 As shown in the figure, the utility model provides a kind of anchor cable sensor based on optical fiber MEMS technology, comprising:

[0027] Annular shell 1, one end is provided with annular cover plate 110;

[0028] Stress ring 2 is clamped in annular shell 1, and stress ring 2 includes cylindrical body 210 and two cylindrical connecting bodies 220, two cylindrical connecting bodies 220 are respectively arranged at the two ends of cylindrical body 210, and the diameter of cylindrical connecting body 220 is greater than the diameter of cylindrical body 210, the outer side of cylindrical connecting body 220 is provided with sealing ring, sealing ring is in close contact with the inner wall of annular shell 1, one of the cylindrical connecting bodies 220 is provided with boss 240 away from the one end of cylindrical body 210, boss 240 passes through annular cover plate 110, the middle part of cylindrical body 210 is provided with arc-shaped groove 250, and stress ring 2 is provided with anchor cable through hole 260 along its axis;

[0029] MEMS strain gauge 3 includes strain gauge body 310, MEMS chip 320 and collimator 330, strain gauge body 310 is U-shaped as a whole, and the outer side of the two ends of strain gauge body 310 is provided with horizontal connecting plate 340, two horizontal connecting plates 340 are connected to the two ends of cylindrical body 210 of stress ring 2 respectively, MEMS chip 320 is attached to the inner side of one end of strain gauge body 310, and an included angle is formed between MEMS chip 320 and horizontal connecting plate 340, collimator 330 is arranged on one of horizontal connecting plates 340, and the light exit side of collimator 330 passes through one end of strain gauge body 310 and is aligned with MEMS chip 320, and multiple MEMS strain gauges are arrayed along the outer side of cylindrical body 210.

[0030] The anchor cable sensor based on the optical fiber MEMS technology uniformly installs multiple MEMS strain gauges in the circumferential direction of the stress ring 2, and after initial calibration, the size of the light wave returned by the multiple MEMS strain gauges can be analyzed by a demodulator to calculate the stress data in each direction, and the actual stress and eccentric load on the anchor cable are calculated by software to provide reliable data basis for the monitoring system. Based on the advantages of high resolution and high precision of the optical fiber MEMS, the micro displacement can be monitored to provide reliable data support. In addition, sealing rings are installed between the two ends of the stress ring 2 and the annular shell 1 to ensure the normal operation of the sensor in harsh environments such as outdoors and underground.

[0031] Specifically, the annular shell 1 is integrally welded with the annular cover plate 110, the boss 240 on the stress ring 2 is located on the annular cover plate 110, the bottom of the annular cover plate 110 is in contact with the anchor cable tray 7, and the boss 240 on the stress ring 2 is in contact with the fastening nut 8 on the anchor cable. When the rock mass 10 deforms, the stress ring 2 will be compressed under the action of force, and the force will be indirectly converted into the deformation of the MEMS strain gauge, and the light wave will be transmitted to the demodulation device; the arc-shaped groove 250 of the cylindrical main body 210 of the stress ring 2 is used to provide a deformation basis, and the two ends of the MEMS are in contact with the two ends of the cylindrical main body 210, so that the deformation of the stress ring 2 can be converted into the linear change of the relative angle of the MEMS chip 320 and the collimator 330, thereby providing a light change basis; the MEMS strain gauge adopts the optical fiber MEMS technology and is not affected by electromagnetic radiation and temperature changes. It can work stably for a long time in environments with dust, heat, strong electromagnetic radiation and large temperature difference, solving the problems of signal reception and transmission of existing anchor rod cable sensors in harsh working environments; in this embodiment, the MEMS chip 320 is provided as three, and more can also be provided according to actual conditions.

[0032] Further, the MEMS strain gauge 3 further comprises an optical fiber, and the collimator 330 is provided with a through hole, and the optical fiber is arranged at one end of the through hole, and the other end of the through hole is aligned with the MEMS chip 320.

[0033] Specifically, the connection of the optical fiber and the collimator 330 is a conventional means in the industry, and the rear end of the optical fiber is connected to the demodulation device.

[0034] Further, it further comprises an optical fiber leading interface 120, and the optical fiber leading interface 120 is connected to the annular shell 1.

[0035] Specifically, the optical fiber leading interface 120 is used for leading out the optical fibers of all MEMS strain gauges 3 on the stress ring 2.

[0036] Further, a plurality of bolt holes 4 are arranged on the cylindrical connecting body 220 away from the annular cover plate 110, a plurality of through holes 5 are arranged on the annular shell 1, and the plurality of through holes 5 correspond one by one to the bolt holes 4.

[0037] Specifically, the annular shell 1 is connected with the stress ring 2 through screws, and the bolt holes 4 and the through holes 5 can be uniformly arranged in multiple groups in the circumferential direction.

[0038] Further, the two ends of the cylindrical connecting body 220 are provided with multiple L-shaped mounting grooves 211, and the L-shaped mounting grooves 211 are provided with the pressing blocks 6, and the horizontal connecting plates 340 at the two ends of the strain gauge body 310 are fixed in the L-shaped mounting grooves 211 through the pressing blocks 6.

[0039] Specifically, the L-shaped mounting grooves 211 are excavated from the arc-shaped grooves 250 on the cylindrical body 210 of the stress ring 2 to the two ends in multiple groups, and in this embodiment, the L-shaped mounting grooves 211 are provided in six groups, and each two opposite L-shaped mounting grooves 211 form a group for fixing the MEMS strain gauge.

[0040] Further, the horizontal connecting plates 340 at the two ends of the strain gauge body 310 abut against one side groove wall of the L-shaped mounting groove 211.

[0041] Specifically, as described above, the pressing blocks 6 are fastened with one side of the L-shaped mounting groove 211 through screws, and at the same time, the fixing of the MEMS on the stress ring 2 is realized, and since the deformation of the stress ring 2 mainly occurs in the axial direction, the two ends of the strain gauge body 310 abut against the other side of the L-shaped mounting groove 211, which can ensure the synchronous deformation of the strain gauge and the stress ring 2 and reduce the error.

[0042] Further, the inner side of the strain gauge body 310 is also provided with multiple arc-shaped notches 311, and the arc-shaped notches 311 divide the end of the strain gauge body 310 provided with the MEMS chip 320 into multiple linear segments and circular arc segments.

[0043] Specifically, the design of the arc-shaped notches 311 provides a sensitive structure for the strain gauge body 310, which can expand the deformation and increase the sensitivity of the sensor.

[0044] Further, the strain gauge body 310 is made of 40CrNiMo material.

[0045] Specifically, the strain gauge body 310 is made of 40CrNiMo material, which has very small stress deformation hysteresis that can be almost ignored, and the internal stress is eliminated through heat treatment, avoiding the influence of microstructure differences on sensor measurement.

[0046] Further, the cylindrical connecting body 220 is provided with an annular groove 230, and the sealing ring is clamped in the annular groove 230.

[0047] The sealing ring is selected from appropriate materials, and the highest protection level can reach IP67.

[0048] Specifically, the annular groove 230 on the cylindrical body 210 is used for clamping a sealing ring, and the sealing ring is selected from appropriate materials, and the highest protection level can reach IP67.

[0049] Embodiment 2 also provides a test calibration process of the anchor cable sensor based on the optical fiber MEMS technology as follows:

[0050] a. Place the anchor cable sensor based on the optical fiber MEMS technology on the ball pad of the universal pressure testing machine, measure and adjust the distance of the outer diameter of the anchor cable sensor relative to the outer diameter of the ball pad by using the vernier caliper, and ensure that the axis deviation of the anchor cable sensor and the pressure testing machine is not greater than 1mm;

[0051] b. Before formal calibration, the anchor cable sensor is pre-pressed once, and the pre-pressing load is 1000KN. When pre-pressing, the pressure is slowly added and removed, the adding and removing speed is 1500N / s, and the pressure is stabilized for 1min at the maximum load. After pre-pressing, the initial wavelength is stabilized, and then formal calibration is started;

[0052] c. During calibration, start from 0, and stabilize the pressure for 90s at the speed of 1500N / s every 200KN until the full range point is loaded and stabilized for 90s. The actual loading pressure corresponding to the stabilized pressure set at 200KN, 400KN, 600KN, 800KN and 1000KN and the values of the wavelengths of the three channels are recorded by using the calibration software, and then the unloading is performed at the speed of 2000N / s until the complete unloading is performed;

[0053] d. The calibration software is used to calculate and analyze the calibration data, and the sensor calibration coefficient is obtained;

[0054] e. The calibration coefficient is loaded in the calibration software, the loading mode of step four is repeated, and the consistency of the loading pressure of the universal pressure testing machine and the average value measured by the three channels of the calibration software is verified.

[0055] The test calibration process verifies that the sensor precision is 0.1%F.S, and further verifies that the anchor cable sensor based on the optical fiber MEMS technology has the advantages of high precision and is suitable for high-precision application occasions.

[0056] Obviously, the above embodiments are only examples for clearly illustrating, and are not limited to the embodiments. For ordinary skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, all the embodiments are not required to be exhausted. The obvious changes or variations derived therefrom are still within the protection scope of the utility model.

Claims

1. An anchor cable sensor based on fiber-optic MEMS technology, characterized in that, The utility model relates to a kind of MEMS strain gauge, including: Annular shell, one end is provided with annular cover plate; Stress ring is set in the annular shell, the stress ring includes cylindrical main body and two cylindrical connectors, two cylindrical connectors are respectively arranged at both ends of the cylindrical main body, and the diameter of the cylindrical connector is greater than the diameter of the cylindrical main body, the outer side of the cylindrical connector is provided with sealing ring, the sealing ring is close to the inner wall of the annular shell, one end of the cylindrical connector away from the cylindrical main body is provided with boss, the boss passes through the annular cover plate, the middle part of the cylindrical main body is provided with arc slot, the stress ring is provided with anchor cable perforation along its axis; MEMS strain gauge includes strain gauge main body, MEMS chip and collimator, the strain gauge main body is U-shaped as a whole, and the outer side of both ends of the strain gauge main body is provided with horizontal connecting plate, two horizontal connecting plates are connected to both ends of the cylindrical main body of the stress ring respectively, the MEMS chip is attached to the inner side of one end of the strain gauge main body, and the MEMS chip is provided with included angle between horizontal connecting plate, the collimator is arranged on one of the horizontal connecting plates, and the light side of the collimator passes through one end of the strain gauge main body and is aligned with the MEMS chip, and the MEMS strain gauge is arrayed with multiple along the outer side of the cylindrical main body.

2. The fiber-optic MEMS-based cable sensor of claim 1, wherein: The MEMS strain gauge further includes an optical fiber, and the collimator is provided with a through hole, one end of the optical fiber is inserted into the through hole, and the other end of the through hole is aligned with the MEMS chip.

3. The fiber-optic MEMS-based cable sensor of claim 2, wherein: It also includes a fiber outlet interface, and the fiber outlet interface is connected to the annular shell.

4. The fiber-optic MEMS-based cable sensor of claim 1, wherein: A plurality of bolt holes are provided on the cylindrical connector away from the annular cover plate, and a plurality of through holes are provided on the annular shell, and the through holes correspond one by one to the bolt holes.

5. The fiber-optic MEMS-based cable sensor of claim 1, wherein: Both ends of the cylindrical connector are provided with a plurality of L-shaped mounting grooves, and a pressing block is arranged on the L-shaped mounting groove, and the horizontal connecting plate at both ends of the strain gauge main body is fixed in the L-shaped mounting groove through the pressing block.

6. The fiber-optic MEMS-based cable sensor of claim 5, wherein: The horizontal connecting plate at both ends of the strain gauge main body abuts against one side groove wall of the L-shaped mounting groove.

7. The fiber-optic MEMS-based cable sensor of claim 1, wherein: The inner side of the strain gauge main body is also provided with a plurality of arc notches, and the arc notches divide the end of the strain gauge main body provided with the MEMS chip into a plurality of straight line segments and circular arc segments.

8. The fiber-optic MEMS-based cable sensor of claim 1, wherein: The strain gauge main body is made of 40CrNiMo material.

9. The fiber-optic MEMS-based cable sensor of claim 1, wherein: The cylindrical connector is provided with an annular groove, and the sealing ring is clamped in the annular groove.

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