Scraper conveyor chain tension monitoring system and method based on fiber bragg grating

Abstract

The invention relates to the technical field of scraper conveyors, in particular to a scraper conveyor chain tension monitoring system and method based on a fiber bragg grating, and the system comprises wavelength demodulation equipment, data processing equipment, a supporting seat, laser emission equipment and the fiber bragg grating; an accommodating part is formed in an area, opposite to a scraper of the scraper conveyor, of the supporting seat, a first end part of the fiber bragg grating is fixed at one end, opposite to the scraper, of the accommodating part, and the other end of the accommodating part extends out of the supporting seat; bragg gratings with equal pitches are engraved on the first end part, the second end part of the fiber grating extends out of the supporting seat through the accommodating part, the laser emission equipment emits laser to the second end part of the fiber grating, and the laser is transmitted to an area where the Bragg gratings are located along the fiber grating; the wavelength demodulation equipment is connected with the second end part of the fiber grating; and the data processing equipment is connected with the wavelength demodulation equipment. Therefore, the detection efficiency and the detection precision of chain tension detection are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of scraper conveyors, in particular to a scraper conveyor chain tension monitoring system and method based on fiber gratings. BACKGROUND

[0002] The scraper conveyor is the core equipment of fully mechanized coal mining in the working face, and its operation logic is as follows: the motor drives the hydraulic coupler, the reducer and the chain wheel in turn, and drives the scraper to complete the circular motion by the meshing action of the chain wheel and the chain, and finally realizes the conveying of the material on the middle plate from the tail to the head. As the core traction component, the chain not only directly transmits the traction force and scrapes the material, but also bears the dual action of static load and dynamic load under the condition of sliding friction, and is also affected by the erosion of mine water, resulting in high failure rate. With the increase of running time, the reliability of the scraper conveyor decreases exponentially, and once a fault occurs, it is difficult and time-consuming to maintain, and it will also seriously affect the production efficiency of the coal mine, so the fault monitoring of the chain is particularly important.

[0003] Chain tension is a core indicator reflecting its running state: insufficient tension is easy to cause the chain to relax and accumulate at the driving chain wheel separation, and then induce chain breakage, chain jamming or chain wheel tooth breakage, etc. Excessive tension will cause the overall power consumption of the scraper conveyor to abnormally increase. The hydraulic cylinder configured at the tail of the scraper conveyor can adjust the distance between the head and the tail chain wheel by extension and retraction, thereby realizing the adjustment of the chain tension, which makes the oil cylinder pressure and the chain tension have a certain correlation. The traditional monitoring technology is based on this correlation, and a pressure sensor is installed in the hydraulic circuit of the tail extension cylinder to indirectly reflect the chain tension by monitoring the oil cylinder pressure, but this method has obvious limitations, and repeated calibration work needs to be carried out for different models of scraper conveyors, which ultimately leads to high time cost and low efficiency of chain tension detection. And the way of monitoring the oil cylinder pressure, the oil cylinder pressure will be disturbed by the characteristics of the hydraulic system itself, environmental factors and mechanical coupling in the transmission process, resulting in low tension detection accuracy of the scraper conveyor. SUMMARY

[0004] In order to solve the technical problems of high time cost, low detection efficiency and low detection accuracy of chain tension detection, the purpose of the present application is to provide a scraper conveyor chain tension monitoring system and method based on fiber gratings, and the technical solution adopted is as follows:

[0005] In a first aspect, the embodiment of the present application discloses a chain tension monitoring system of a scraper conveyor based on a fiber grating, which comprises a wavelength demodulation device, a data processing device, a support seat, a laser emitting device and a fiber grating. The support seat is arranged at a position of a side of a transition groove of the scraper conveyor. A containing portion is arranged in a region opposite to the scraper of the scraper conveyor. A first end portion of the fiber grating is fixed to one end of the containing portion opposite to the scraper. The other end of the containing portion extends to the outside of the support seat. A Bragg grating with equal grating pitches is engraved on the first end portion. A second end portion of the fiber grating extends out of the support seat through the containing portion. The laser emitting device emits laser to the second end portion of the fiber grating. The laser is transmitted along the fiber grating to the region where the Bragg grating is located. In the case that the chain passes and presses the support seat, the deformation of the support seat is transmitted to the first end portion of the fiber grating, so that the grating pitch of the Bragg grating on the first end portion changes. In the case that the grating pitch of the Bragg grating changes, the reflection wavelength of the Bragg grating is offset, and the wavelength variation is generated. The wavelength demodulation device is connected to the second end portion of the fiber grating, and is used for collecting the wavelength variation of the Bragg grating in real time. The data processing device is connected to the wavelength demodulation device, and is used for calculating the pressure received by the support seat according to the wavelength variation, the parameters of the fiber grating, the elastic modulus of the support seat and the contact area between the support seat and the scraper. The pressure received by the support seat is the pressure applied by the chain on the transition groove. The tension of the chain of the scraper conveyor is calculated according to the linear relationship between the pressure received by the support seat and the tension of the chain of the scraper conveyor.

[0006] In a second aspect, the embodiment of the present application discloses a chain tension monitoring method of a scraper conveyor based on a fiber grating, which comprises the following steps. The wavelength variation of the fiber grating is obtained. The pressure received by the support seat is calculated according to the wavelength variation, the parameters of the fiber grating, the elastic modulus of the support seat and the contact area between the support seat and the scraper. The pressure received by the support seat is the pressure applied by the chain on the transition groove. The tension of the chain of the scraper conveyor is calculated according to the linear relationship between the pressure received by the support seat and the tension of the chain of the scraper conveyor.

[0007] Through the technical scheme disclosed by the embodiment of the present application, the chain pressure is directly borne by the support seat, the Bragg grating of the fiber grating is used to convert the deformation into a wavelength change amount, and the tension is derived by combining the fixed structure parameters such as the elastic modulus and the contact area of the support seat and the parameters of the fiber itself, which greatly shortens the early debugging time, reduces the time cost and labor cost of detection, and improves the detection efficiency. The load is directly transmitted through the direct contact between the support seat and the chain, the deformation directly acts on the fiber grating, the wavelength change amount can directly reflect the change of the load, the error interference of the intermediate transmission link is reduced, and the Bragg grating has the characteristics of anti-electromagnetic interference and anti-mine water erosion, which further guarantees the signal stability and improves the chain tension detection precision of the scraper conveyor. The wavelength demodulation device can collect the wavelength change amount of the Bragg grating in real time, the data processing device can quickly complete the calculation of the pressure and the tension, and the real-time dynamic monitoring of the chain tension is realized. When the chain tension is abnormally large or small, the signal can be captured and fed back in time to avoid accidents such as chain breakage and chain jam caused by abnormal tension, avoid the problem of response lag, and ensure the reliable operation of the scraper conveyor. The support seat is fixed to the transition groove side, without the need to modify the original structure of the scraper conveyor, convenient to install, and the sensing unit structure formed by the fiber grating and the Bragg grating is small, wear-resistant and corrosion-resistant, can adapt to the harsh working environment of the coal mine, has a longer service life and stronger environmental tolerance, and can realize long-term stable monitoring of the chain tension. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 A structure schematic diagram of a scraper conveyor chain tension monitoring system based on a fiber grating is provided for the embodiment of the present application.

[0009] Figure 2 A structure schematic diagram of a scraper conveyor is provided for the embodiment of the present application.

[0010] Figure 3 A flowchart of a scraper conveyor chain tension monitoring method based on a fiber grating is provided for the embodiment of the present application.

[0011] The drawings show: wavelength demodulation device 101, data processing device 102, support seat 103, fiber grating 104, containing part 105, protection plate 106, bolt 107, vertical ring 201, flat ring 202, scraper 203. DETAILED DESCRIPTION

[0012] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a fiber Bragg grating-based scraper conveyor chain tension monitoring system and method proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0013] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The specific implementation of a fiber Bragg grating-based scraper conveyor chain tension monitoring system provided by this invention is described below in conjunction with the accompanying drawings.

[0014] Figure 1 This is a schematic diagram of a fiber Bragg grating-based scraper conveyor chain tension monitoring system provided in an embodiment of the present invention. Figure 2 This is a structural schematic diagram of a scraper conveyor provided in an embodiment of the present invention. Figure 3 This is a flowchart illustrating a method for monitoring chain tension in a scraper conveyor based on a fiber Bragg grating, as provided in an embodiment of the present invention.

[0015] like Figure 1 As shown in the figure, an embodiment of the present invention provides a scraper conveyor chain tension monitoring system based on fiber Bragg grating, comprising: wavelength demodulation device 101, data processing device 102, support base 103, laser emitting device (not shown in the figure) and fiber Bragg grating 104.

[0016] A support seat is provided at the side of the transition trough of the scraper conveyor. A receiving part 105 is opened in the area opposite to the scraper of the scraper conveyor. The first end of the fiber optic grating 104 is fixed at one end of the receiving part 105 opposite to the scraper, and the other end of the receiving part 105 extends to the outside of the support seat 103.

[0017] A Bragg grating with equal pitch is etched on the first end. The second end of the fiber grating 104 extends out of the support 103 through the receiving part 105. The laser emitting device emits a laser to the second end of the fiber grating 104. The laser is transmitted along the fiber grating 104 to the area where the Bragg grating is located. When the chain passes by and squeezes the support 103, the support 103 deforms and the deformation is transmitted to the first end of the fiber grating 104, so that the grating pitch of the Bragg grating at the first end changes. When the grating pitch of the Bragg grating changes, the reflected wavelength of the Bragg grating shifts, resulting in a wavelength change.

[0018] The wavelength demodulation device 101 is connected to the second end of the fiber optic grating 104 and is used to acquire the wavelength change of the Bragg grating in real time.

[0019] The data processing device 102 is connected to the wavelength demodulation device 101 and is used to calculate the pressure on the support 103 based on the wavelength change, the parameters of the fiber grating 104, the elastic modulus of the support 103, and the contact area between the support 103 and the scraper. The pressure on the support 103 is the pressure applied to the transition groove by the chain. The device also calculates the tension on the chain of the scraper conveyor based on the linear relationship between the pressure on the support 103 and the tension of the chain of the scraper conveyor.

[0020] Specifically, such as Figure 1 As shown, the fiber optic grating-based scraper conveyor chain tension monitoring system in this embodiment of the invention is positioned above the chain, which includes a vertical ring 201, a flat ring 202, and a scraper 203. The chain rotates cyclically under the drive of the sprocket. When the tail tensioning cylinder of the scraper conveyor tensions the chain, the components such as the vertical ring 201, flat ring 202, and scraper 203 come into close contact with and press against the support seat 103. As the chain tension increases, the chain exerts increasing pressure on the upper edge of the transition groove. The chain tension and the pressure exerted by the chain on the upper edge of the transition groove are positively correlated. Therefore, this embodiment of the invention uses the measurement of the pressure exerted by the chain on the upper edge of the transition groove to determine the tension on the chain.

[0021] Further, the chain will generate pressure on the upper edge of the transition groove, a support seat 103 is arranged on the upper edge of the transition groove, the support seat 103 will generate different strain under different pressure, therefore, the embodiment of the present application sets a fiber grating 104 on the support seat 103 based on the grating strain principle. The fiber grating 104 is a kind of parallel slits with regular changes in spacing written on the fiber core by using the photosensitivity of the fiber material. Among them, the fiber grating 104 with uniform and consistent grating pitch is called Bragg grating. Once the Bragg grating of the optical fiber is affected by stress or temperature change, the grating pitch of the Bragg grating will change, the wavelength of the reflected wave will also change, and different wavelengths will be reflected, so the wavelength change amount of the Bragg grating can be measured. The wavelength demodulation device 101 in the embodiment of the present application can test the reflected wavelength λ B of the fiber grating 104, since the reflected wavelength λ B and the grating pitch Λ of the fiber grating 104 have a corresponding relationship, the formula is: λ B = 2 nef f Λ, wherein nef f is the refractive index of the optical fiber, therefore, when the grating pitch Λ changes, the wavelength demodulation device 101 can obtain the reflected wavelength λ B in real time, and calculate the wavelength change amount of the Bragg grating based on the reflected wavelength before the grating pitch Λ changes. Therefore, the change amount of the reflected wavelength of the fiber grating 104 is understood to understand the pressure suffered by the fiber grating 104. That is, the embodiment of the present application relates the change amount of the reflected wavelength of the fiber grating 104 to the stress suffered by the support seat 103, the change amount of the reflected wavelength of the fiber grating 104 will directly reflect the stress suffered by the support seat 103, and the pressure applied by the upper edge of the transition groove to the support seat 103 is related to the stress suffered by the support seat 103. Therefore, the pressure of the chain on the upper edge of the transition groove can be judged by the change amount of the reflected wavelength of the fiber grating 104.

[0022] Further, the accommodating portion 105 in the embodiment of the present application can be composed of a cylindrical hole and a rectangular groove, the cylindrical hole and the rectangular groove are in communication with each other, the cylindrical hole is opposite to the scraper, one end of the rectangular groove communicates with the cylindrical hole, and the other end extends to the outside of the support seat 103. The first end of the fiber grating 104 can be fixed in the cylindrical hole by an adhesive, and the cylindrical hole is tightly attached to the adhesive. The other end of the fiber grating 104 extends from the rectangular groove to the outside of the support seat 103.

[0023] Further, as shown in FIG. 4, the embodiment of the present application sets a plurality of fiber gratings 104 on the support seat 103, and the wavelength demodulation device 101 can test the reflected wavelength of each fiber grating 104, and the pressure of the chain on the upper edge of the transition groove can be judged by the change amount of the reflected wavelength of each fiber grating 104. Figure 1As shown, as an optional embodiment of the present application, the embodiment of the present application can be provided with a receiving portion 105 in the top surface of the area opposite to the support seat 103 and the scraper. The scraper conveyor chain tension monitoring device further comprises a protective plate 106 covering the receiving portion 105. In this way, the cover plate covers the receiving portion 105, which can provide physical protection for the fiber Bragg grating 104 in the receiving portion 105, reduce the intrusion of dust, debris and other impurities during the operation of the chain, reduce the risk of damage to the fiber Bragg grating 104, and ensure the stability of the monitoring.

[0024] It is worth noting that the receiving portion 105 can also be provided in the middle position of the area opposite to the support seat 103 and the chain, so that the cover plate is not needed, thereby making the structure of the detection device more simple and reducing the cost.

[0025] Further, the end surface of the support seat 103 opposite to the scraper is provided with a wear-resistant coating, and in addition, the support seat 103 can be made of wear-resistant material, thereby preventing damage to the chain and prolonging the service life of the equipment.

[0026] Further, as an optional embodiment of the present application, the support seat 103 is of a T-shaped structure, the vertical rod of the T-shaped structure is embedded into the transition groove, the horizontal rod of the T-shaped structure is provided with two mounting holes, the mounting holes are symmetrically distributed on both sides of the receiving portion 105, and the horizontal rod of the T-shaped structure is detachably connected with the groove side of the transition groove through the bolts 107 passing through the mounting holes. Figure 1 As shown, the vertical rod of the T-shaped structure in the embodiment of the present application is embedded into the transition groove, thereby ensuring the stability of the monitoring system and improving the stability and reliability of the detection result. The T-shaped vertical rod is embedded into the transition groove, which can stably receive the chain pressure and avoid deviation. The vertical rod of the T-shaped structure is opposite to the scraper, and therefore, the receiving portion 105 is provided in the vertical rod of the T-shaped structure, which can make the force applied by the chain to the mounting groove more conform to the pressure applied by the chain to the transition groove, the overall design makes the stress more balanced, and further improves the stability and precision of the tension monitoring. In addition, the embodiment of the present application adopts the bolts 107 to realize the detachable connection between the horizontal rod of the T-shaped structure and the groove side of the transition groove, which is simple and convenient to assemble and operate, does not need complex tools, and effectively improves the equipment assembly efficiency. The detachable design facilitates the maintenance, replacement or maintenance of the horizontal rod and the groove side of the transition groove, reduces the difficulty and cost of maintenance, and reduces the equipment downtime.

[0027] Further, the first end of the fiber grating 104 is cast in the accommodating portion 105 by epoxy. In the embodiment of the present application, the first end of the grating fiber (the effective sensing section with the Bragg grating inscribed) is first placed flat in the preset mounting position of the accommodating portion, ensuring that the Bragg grating is completely located in the middle region of the accommodating portion without bending and deviation; then low-viscosity and high-bonding-strength epoxy resin glue is injected into the accommodating portion, so that the glue solution fully fills the internal gap of the accommodating portion and completely wraps the first end of the grating fiber and the region where the Bragg grating is located; after the epoxy resin glue is cured at room temperature or cured by low-temperature baking, a dense cured layer is formed. This casting and fixing method can not only firmly lock the first end of the grating fiber in the accommodating portion, avoiding the relative displacement of the fiber when the squeezer chain extrudes the support seat 103, but also ensure that the deformation of the support seat 103 can be completely and synchronously transmitted to the Bragg grating, ensuring the linear correlation between the wavelength change and the load; at the same time, the cured epoxy resin layer can also form a sealed protection for the grating fiber and the Bragg grating, isolating the corrosive media such as mine water and dust in the coal mine, reducing the erosion of the external environment on the sensing unit, prolonging its service life, and the elastic modulus of the epoxy resin is adapted to the coating layer of the grating fiber, which can avoid the influence of stress residual after curing on the detection accuracy.

[0028] Further, as an optional embodiment of the present application, the fiber grating 104 is a single-mode fiber grating 104, the core diameter of the fiber grating 104 is 7-9 μm, the coating layer diameter is 110-220 μm, and the Bragg grating is inscribed at the central axis of the core. Specifically, the single-mode fiber grating 104 has the characteristics of low transmission loss and strong signal stability, and can accurately respond to the slight deformation of the support seat 103, adapting to the high-precision monitoring demand of the chain tension. Among them, the core diameter of the fiber grating 104 is limited to 7-9 μm (preferably 8 μm in the embodiment of the present application), which can ensure stable transmission of laser signals along the core and reduce the interference of mode dispersion on the sensing signal; the coating layer diameter is set to 110-220 μm (preferably 125 μm), and the coating layer is made of abrasion-resistant and corrosion-resistant polyimide material, which can not only enhance the mechanical strength of the fiber grating 104 and avoid damage caused by friction and collision during installation and use, but also can preliminarily isolate the erosion of external media such as mine water and dust. The Bragg grating is accurately inscribed at the central axis of the core, ensuring that the periodic refractive index modulation region of the grating completely coincides with the core center, so that the incident laser can form efficient coupling with the grating, ensuring the stability and consistency of the reflected wavelength, avoiding the distortion of the linear relationship between the wavelength change and the strain caused by the inscribed deviation of the grating, and further improving the accuracy and reliability of the chain tension detection.

[0029] Further, as an optional embodiment of the present application, the grating pitch of the Bragg grating is 0.5 to 2 pm, and the effective sensing section of the Bragg grating is located entirely in the middle region of the accommodating portion 105. Specifically, the grating pitch of the Bragg grating is controlled in the range of 0.5 to 2 pm (preferably 1 pm), which is matched with the effective refractive index of the single-mode fiber core, so that the Bragg grating has high reflectivity and narrow bandwidth characteristics for the reflection wavelength corresponding to the target monitoring waveband, ensuring high sensitivity response to the slight deformation of the support seat 103 and meeting the detection requirements of the slight change of the chain tension. At the same time, when the grating fiber is installed and fixed, the effective sensing section of the Bragg grating needs to be accurately positioned so as to be entirely in the middle region of the accommodating portion 105, specifically, the two ends of the effective sensing section and the edge of the slot of the accommodating portion 105 and the boundary of the solidified layer all maintain a predetermined safe distance, avoiding the effective sensing section from being close to the edge of the accommodating portion 105 or the stress concentration area of the solidified layer. This layout design can ensure that the effective sensing section can uniformly bear the deformation load when the support seat 103 is elastically deformed due to the extrusion of the scraper chain, avoid local stress concentration leading to non-uniform change of the grating pitch, and protect the linear correspondence between the wavelength change and the deformation of the support seat 103 and the chain tension, further improving the accuracy and data repeatability of the tension detection, reducing the interference of the edge effect on the sensing performance, and prolonging the service life of the grating.

[0030] Further, the laser emission device is aligned with the second end of the fiber grating 104 in the laser emission direction. The embodiment of the present application selects a broadband laser source, and the emitted laser waveband covers the preset reflection wavelength range of the Bragg grating. This ensures that the laser signal is stably transmitted along the grating fiber to the area where the Bragg grating is located, providing a continuous and reliable incident light signal for sensing and detection. The laser emission device is accurately connected with the second end of the grating fiber through the fiber adapter, and an FC / APC standard joint is used at the connection position to reduce the coupling loss in the laser transmission process, so as to ensure that the incident light energy can efficiently act on the Bragg grating and ensure the intensity and signal-to-noise ratio of the grating reflection signal, laying a foundation for the accurate acquisition of the wavelength change by the subsequent wavelength demodulation device 101.

[0031] Further, the wavelength demodulation device 101 converts the wavelength change into a digital signal and transmits it to the data processing device 102. The data processing device 102 calculates the tension according to the wavelength change. The data processing device 102 can be a computer or other electronic device.

[0032] Specifically, when the fiber grating 104 is subjected to pressure, the fiber will produce a slight deformation, causing the center wavelength of the Bragg grating to drift linearly when calculating the tension of the chain of the scraper conveyor. The relationship between the wavelength change of the fiber grating 104, the parameters of the fiber grating 104, and the strain of the fiber is specifically represented as follows: ;

[0033] In the above formula, This indicates the wavelength change of the fiber grating 104. Indicates the reflection wavelength of fiber optic grating 104, The coefficient of thermal expansion of fiber Bragg grating 104, The thermo-optic coefficient of fiber grating 104, The photoelastic coefficient of the fiber grating 104 material, This refers to the change in temperature. This refers to the strain of the optical fiber. It is worth noting that the strain generated in the optical fiber should be consistent with the strain of the support 103.

[0034] Furthermore, according to the generalized Hooke's law, in the elastic stage, the stress and strain of the material (support 103) exhibit a linear relationship, specifically expressed as follows:

[0035] ;

[0036] In the above formula, For the stress on the support 103, For the elastic modulus of the material of support 103, For the strain of support 103.

[0037] Furthermore, the pressure and strain acting on the support 103 satisfy the following relationship:

[0038] In the above formula, This indicates the pressure exerted on support 103. This indicates the stress experienced by the support 103. This indicates the contact area between the support base 103 and the scraper.

[0039] Therefore, by applying the above equations, the pressure exerted on the support 103 can be determined, as shown in the following equation: ;

[0040] It is worth noting that the Chinese meanings of the parameters in this formula are the same as the Chinese meanings of the parameters in the above equations, and they can be referred to each other. The embodiments of this invention will not be repeated here.

[0041] Furthermore, such as Figure 2 As shown, Figure 2 This is a schematic diagram of a scraper conveyor according to an embodiment of the present invention. The scraper conveyor includes the fiber optic grating-based scraper conveyor chain tension monitoring system and the scraper conveyor body described in the above embodiment. Wherein, as... Figure 2As shown, there is a linear relationship between the tension on the chain and the pressure exerted by the chain on the transition groove. By decomposing the pressure exerted by the chain on the transition groove, the horizontal component is the force with the same magnitude but opposite direction to the tension. Therefore, an equation can be established between the tension on the chain and the pressure exerted by the chain on the transition groove: F1 = k1F, k1 = COSA, where F1 represents the tension, F represents the pressure at the transition groove, and COSA is between 0 and 1. Thus, the tension on the chain can be obtained.

[0042] It is worth noting that the embodiments of the present invention can also be installed at the head transition trough or tail transition trough of the scraper conveyor.

[0043] The technical solution provided by this invention directly bears the chain pressure through a support base. It utilizes the Bragg grating of a fiber optic grating to convert deformation into wavelength change. By combining the support base's elastic modulus, contact area, and other fixed structural parameters with the fiber's own parameters to derive tension, the initial debugging time is significantly shortened, reducing testing time and labor costs and improving testing efficiency. Through direct contact between the support base and the chain, the load is transferred, and the deformation directly acts on the fiber optic grating. The wavelength change directly reflects the load change, reducing errors and interference from intermediate transmission links. Furthermore, the Bragg grating has anti-electromagnetic interference and anti-mine water erosion characteristics, further ensuring signal stability and improving the chain tension detection accuracy of the scraper conveyor. The wavelength demodulation equipment can collect the wavelength change of the Bragg grating in real time, and the data processing equipment quickly completes the calculation of pressure and tension, realizing real-time dynamic monitoring of chain tension. When abnormal chain tension occurs (too high or too low), the signal can be captured and fed back in a timely manner, avoiding accidents such as chain breakage or jamming caused by abnormal tension, avoiding response lag problems, and ensuring the reliable operation of the scraper conveyor. The support base is fixed to the side of the transition trough, eliminating the need to modify the original structure of the scraper conveyor. It is easy to install, and the sensing unit structure composed of fiber optic gratings and Bragg gratings is compact, wear-resistant, and corrosion-resistant. It can adapt to the harsh working environment in coal mines, with a longer service life and stronger environmental tolerance, enabling long-term stable monitoring of chain tension.

[0044] Furthermore, such as Figure 3 As shown, Figure 3 This is a flowchart illustrating a method for monitoring chain tension in a scraper conveyor based on a fiber Bragg grating, provided in an embodiment of the present invention. This method is based on the fiber Bragg grating-based scraper conveyor chain tension monitoring system mentioned in the above embodiment. The method includes:

[0045] Step S301: Obtain the wavelength change of the fiber grating.

[0046] Step S302, according to the wavelength variation, the parameters of the fiber grating, the elastic modulus of the support seat, the contact area of the support seat and the scraper, the pressure received by the support seat is calculated, and the pressure received by the support seat is the pressure applied by the chain on the transition groove.

[0047] Wherein, as an optional embodiment of the present application, according to the wavelength variation, the parameters of the fiber grating, the elastic modulus of the support seat, the contact area of the support seat and the scraper, the pressure received by the support seat includes: according to the wavelength variation of the Bragg grating, the parameters of the fiber grating, the linear relationship between the elastic modulus of the support seat and the stress received by the support seat, the stress received by the support seat is calculated; According to the linear relationship between the stress received by the support seat, the contact area of the support seat and the scraper and the pressure received by the support seat, the pressure received by the support seat is calculated, and the pressure received by the support seat is the pressure applied by the chain on the transition groove; According to the linear relationship between the pressure received by the support seat and the tension of the chain of the scraper conveyor, the tension of the chain of the scraper conveyor is calculated.

[0048] Specifically, specifically, when the fiber grating is subjected to pressure, the fiber will produce a small deformation, resulting in the linear change of the center wavelength of the Bragg grating. The relationship between the wavelength variation of the fiber grating, the parameters of the fiber grating and the strain of the fiber is specifically expressed as follows: ;

[0049] In the above formula, represents the wavelength variation of the fiber grating, represents the reflection wavelength of the fiber grating, is the thermal expansion coefficient of the fiber grating, is the thermo-optic coefficient of the fiber grating, is the photoelastic coefficient of the material of the fiber grating, is the temperature variation; is the strain of the fiber. It is worth noting that the strain of the fiber and the strain of the support seat should be consistent.

[0050] Further, according to the generalized Hooke's law, the stress and strain of the material (support seat) in the elastic stage present a linear relationship, which is specifically expressed as follows: ;

[0051] In the above formula, is the stress received by the support seat, is the elastic modulus of the material of the support seat, is the strain of the support seat.

[0052] Further, the pressure received by the support seat and the strain satisfy the following relationship:

[0053] In the above formula, represents the pressure on the support seat, represents the stress on the support seat, represents the contact area of the support seat and the scraper.

[0054] Therefore, the pressure on the support seat can be solved by the above equation relationship. Namely, as follows: ;

[0055] It is worth noting that the Chinese meaning of each parameter in this formula is the same as that of each parameter in the above equation, which can be referred to each other, and the embodiments of the present application will not be repeated here.

[0056] Step S303, according to the linear relationship between the pressure on the support seat and the tension of the chain of the scraper conveyor, the tension of the chain of the scraper conveyor is calculated.

[0057] Specifically, as shown above Figure 2 , the tension of the chain and the pressure of the chain on the transition groove present a linear relationship, by decomposing the pressure of the chain on the transition groove, the horizontal component is the same size as the tension, and the direction is opposite, therefore, the equation relationship between the tension of the chain and the pressure of the chain on the transition groove is established: F1=k1F, k1=COSA, wherein, F1 represents the tension, F represents the pressure on the transition groove, COSA is between 0 and 1. In this way, the tension of the chain can be obtained.

[0058] The technical scheme provided by the embodiment of the present application directly receives the chain pressure through the support seat, converts the deformation into the wavelength change amount by using the Bragg grating of the fiber grating, and deduces the tension by combining the fixed structure parameters such as the elastic modulus and the contact area of the support seat and the fiber itself parameters, which greatly shortens the early debugging time, reduces the time cost and the labor cost of detection, and improves the detection efficiency. The load is directly transmitted through the direct contact between the support seat and the chain, the deformation directly acts on the fiber grating, the wavelength change amount can directly reflect the load change, the error interference of the intermediate transmission link is reduced, and the Bragg grating has the characteristics of anti-electromagnetic interference and anti-mine water erosion, which further guarantees the signal stability and improves the chain tension detection precision of the scraper conveyor. The wavelength demodulation equipment can collect the wavelength change amount of the Bragg grating in real time, the data processing equipment quickly completes the calculation of the pressure and the tension, and realizes the real-time dynamic monitoring of the chain tension. When the chain tension appears abnormal conditions such as too large or too small, the signal can be captured and fed back in time, accidents such as chain breakage and chain jamming caused by abnormal tension are avoided, the problem of response lag is avoided, and the reliable operation of the scraper conveyor is ensured. The support seat is fixed to the transition groove side, the original structure of the scraper conveyor does not need to be modified, the installation is convenient, the sensing unit structure formed by the fiber grating and the Bragg grating is small, wear-resistant and corrosion-resistant, can adapt to the harsh working environment of the coal mine, has a longer service life and stronger environmental tolerance, and can realize long-term stable monitoring of the chain tension.

[0059] It should be noted that the chain tension monitoring method of the scraper conveyor based on the fiber grating in the embodiment of the present application has the same or similar implementation manner and beneficial effects as the chain tension monitoring system of the scraper conveyor based on the fiber grating described above, and can be mutually referred to, and the embodiment of the present application will not be described here.

[0060] It should be noted that: the above-mentioned sequence of the embodiments is only for description, and does not represent the advantages and disadvantages of the embodiments. The processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are possible or can be advantageous.

[0061] Each embodiment in the specification is described in a progressive manner, and the same or similar parts between each embodiment can be mutually referred to, and each embodiment mainly describes the differences from other embodiments.

Claims

1. A fiber grating based flight chain tension monitoring system, characterized by, The fiber grating-based scraper conveyor chain tension monitoring system comprises a wavelength demodulation device, a data processing device, a support seat, a laser emission device and a fiber grating. The support seat is provided at a position of a side wall of a transition groove of the scraper conveyor, and a receiving portion is formed in an area opposite to a scraper of the scraper conveyor. A Bragg grating with equal grating pitches is engraved on the first end portion of the fiber grating, and a second end portion of the fiber grating extends out of the support seat through the receiving portion. The laser emission device emits laser to the second end portion of the fiber grating, and the laser is transmitted along the fiber grating to a region where the Bragg grating is located. The wavelength demodulation device is connected to the second end portion of the fiber grating to collect the wavelength variation of the Bragg grating in real time.

2. The fiber grating based flighted conveyor chain tension monitoring system of claim 1, wherein, The data processing device is connected to the wavelength demodulation device to calculate the pressure on the support seat according to the wavelength variation, parameters of the fiber grating, an elastic modulus of the support seat, and a contact area between the support seat and the scraper.

3. The fiber grating based flighted conveyor chain tension monitoring system of claim 1, wherein, The fiber grating is a single-mode fiber grating, the fiber grating has a core diameter of 7-9 μm and a coating layer diameter of 110-220 μm, and the Bragg grating is engraved at a central axis of the core. The receiving portion is formed in a top surface of the area opposite to the scraper, and a protection plate is arranged above the receiving portion.

5. The fiber grating based flighted conveyor chain tension monitoring system of claim 1, wherein, 4. The fiber grating-based scraper conveyor chain tension monitoring system according to claim 1, wherein an end surface opposite to the scraper of the support seat is provided with a wear-resistant coating.

6. The fiber grating based flighted conveyor chain tension monitoring system of claim 1, wherein, The support seat has a T-shaped structure, a vertical rod of the T-shaped structure is embedded into the transition groove, two mounting holes are formed in a horizontal rod of the T-shaped structure, the mounting holes are symmetrically arranged on two sides of the receiving portion, and the horizontal rod of the T-shaped structure is detachably connected to a side wall of the transition groove through bolts passing through the mounting holes.

7. The fiber grating based flighted conveyor chain tension monitoring system of claim 1, wherein, The grating pitch of the Bragg grating is 0.5-2 μm, and an effective sensing segment of the Bragg grating is completely located in a middle region of the receiving portion.

8. A fiber grating based flight chain tension monitoring method, characterized in that, The first end portion of the fiber grating is cast into the receiving portion by epoxy resin. The fiber grating-based scraper conveyor chain tension monitoring system according to any one of claims 1-7 comprises: acquiring the wavelength variation of the fiber grating; According to the wavelength variation, the parameter of the fiber grating, the elastic modulus of the support seat, and the contact area between the support seat and the scraper, the pressure on the support seat is calculated, and the pressure on the support seat is the pressure of the chain on the transition groove; According to the linear relationship between the pressure on the support seat and the tension of the chain of the scraper conveyor, the tension of the chain of the scraper conveyor is calculated.

9. The fiber grating based flighted conveyor chain tension monitoring method of claim 8, wherein, The calculation of the pressure on the support seat according to the wavelength variation, the parameter of the fiber grating, the elastic modulus of the support seat, and the contact area between the support seat and the scraper includes: According to the wavelength variation of the Bragg grating, the parameter of the fiber grating, the linear relationship between the elastic modulus of the support seat and the stress on the support seat, and the stress on the support seat is calculated; According to the linear relationship between the stress on the support seat, the contact area between the support seat and the scraper, and the pressure on the support seat, the pressure on the support seat is calculated, and the pressure on the support seat is the pressure of the chain on the transition groove; According to the linear relationship between the pressure on the support seat and the tension of the chain of the scraper conveyor, the tension of the chain of the scraper conveyor is calculated.

10. The fiber grating based flighted conveyor chain tension monitoring method of claim 8, wherein, The calculation of the tension of the chain of the scraper conveyor according to the linear relationship between the pressure on the support seat and the tension of the chain of the scraper conveyor includes: Based on the linear relationship between the pressure and the tension of the chain of the scraper conveyor, a linear equation relationship between the pressure and the tension is established; Based on the linear equation relationship, the tension of the chain is solved.

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