A track system for a greenhouse

Abstract

The application discloses a track system of a greenhouse, belongs to the technical field of agricultural facilities, and is a transportation device in a greenhouse, wherein the track system comprises a track body, a track changing device and a closed-loop control device, the track body is used for bearing a transportation device, the track changing device is connected with the track body and is used for switching a driving path of the transportation device, the closed-loop control device is electrically connected with the track body and the track changing device, is used for monitoring an operation state of the track body and controlling a switching action of the track changing device, and the track body is a honeycomb gradient composite structure. The application can reduce track vibration noise, prolong track service life, improve track changing efficiency, adapt to agricultural automation operation requirements such as seedling transplanting, water and fertilizer conveying and fruit picking in the greenhouse, and guarantee the stability of a crop growth environment and the continuity of agricultural production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of agricultural facilities, in particular to a track system of a greenhouse. BACKGROUND

[0002] With the rapid development of modern agricultural technology, as an important carrier of efficient agricultural production, greenhouse has been widely used in the large-scale planting of crops such as vegetables, flowers and seedlings. Its core requirement is to realize the precise management of crop growth in the whole cycle through automatic equipment, including timed transplanting of seedlings (matching the growth window of crop seedling stage), quantitative delivery of water and fertilizer (following the nutrient demand of crop growth period), timely picking of fruits (avoiding over-mature loss), and track transportation system as the core of the moving line of these automatic operations, its performance directly determines the agricultural production efficiency, the stability of crop growth environment and the operation cost.

[0003] The invention patent with publication number CN110741848B discloses a mobile greenhouse system for field crop phenotype analysis and a transportation track, wherein the transportation track includes a plurality of main tracks, a sub-track arranged at the end of the main track, and a transfer track installed on the sub-track; the main track and the transfer track both include double-track tracks; the transfer track can move relative to the sub-track to make the transfer track and the end of any main track butt joint to form an extended track of the main track; wherein the mobile greenhouse system includes the transportation track, a plurality of greenhouses and a camera device, the greenhouses and the camera device can move on the double-track tracks of the main track and the transfer track respectively, and the double-track track of the main track is provided with a test field. The greenhouse and the camera device in the present application can be flexibly switched on different main tracks through the sub-track and the transfer track, and can move on the double-track tracks respectively without interfering with each other, and the functions of crop growth environment simulation and shooting monitoring are realized at the same time.

[0004] At present, the track equipment commonly used in greenhouse mainly adopts single metal material, such as ordinary carbon steel or simple composite material. Although the metal track has strong bearing capacity, it has the following significant defects:

[0005] Firstly, the wear resistance is poor. Under the load action of the long-term reciprocating operation of the transportation equipment, the surface of the track is easy to produce wear and fatigue cracks, which shortens the service life, and usually needs to be replaced in 1-2 years;

[0006] Secondly, the vibration reduction performance is insufficient. The rigid characteristics of metal material make the vibration and noise generated in the transportation process larger, which not only affects the stability of the equipment parts, but also may interfere with the growth environment of the greenhouse crops;

[0007] Thirdly, the anti-aging performance is weak. The high temperature and high humidity environment in the greenhouse is easy to cause the rust of the metal track, which further reduces its structural strength.

[0008] In the aspect of track switching function, the prior art mostly adopts manual switching or simple mechanical track switching. Manual track switching needs manual operation of track docking, which is not only low in efficiency (5-10 minutes are consumed for single track switching), but also difficult to guarantee docking accuracy, and is prone to track joint jamming. Simple mechanical track switching realizes semi-automation, but lacks intelligent control mechanism, and cannot adjust track switching speed and stability according to dynamic parameters such as transportation load and track state, and is prone to track switching failure under heavy load or track wear.

[0009] In addition, the existing greenhouse track equipment generally lacks effective state monitoring and life prediction means. Traditional track maintenance mainly relies on manual inspection, which has problems of long detection period and high missed detection rate, and it is difficult to grasp the fatigue damage state of the track in real time. When the track suddenly fails, it will cause transportation interruption, seriously affect the production progress of the greenhouse, and even cause equipment damage or safety accidents. Although some industrial fields have begun to apply sensing technology to monitor the track state, due to the particularity of the greenhouse environment (high temperature and humidity, and much dust), the conventional sensing equipment is prone to interference, and there is a lack of special life prediction model for composite material tracks, which cannot realize accurate residual life evaluation and early warning. SUMMARY

[0010] The purpose of the present application is to provide a track system for a greenhouse, which can effectively solve the technical problems of large frictional vibration between the track and the wheel set, insufficient weather resistance and load capacity of the track material, and lack of effective fatigue life prediction and active maintenance mechanism in the prior art.

[0011] To solve the above technical problems, the technical solution adopted by the present application is:

[0012] A track system for a greenhouse, comprising:

[0013] a track body, the track body being used for carrying a transportation device;

[0014] a track switching device, the track switching device being connected with the track body and being used for switching the running path of the transportation device;

[0015] a closed-loop control device, the closed-loop control device being electrically connected with the track body and the track switching device, and being used for monitoring the running state of the track body and controlling the switching action of the track switching device;

[0016] wherein the track body is a honeycomb gradient composite structure, the honeycomb gradient composite structure comprises, from top to bottom along the direction perpendicular to the laying plane, a composite material surface layer, a honeycomb damping layer and a micro-textured base layer; the track switching device comprises a base, a plurality of alternative track segments arranged on the base, and a driving unit connected with the base, the driving unit being used for driving the base to move and then realizing alignment of one of the alternative track segments with the track body;

[0017] The closed-loop control device comprises a fiber Bragg grating sensing module implanted in the track body, a data processing module connected with the sensing module, and a central controller electrically connected with the data processing module, the variable track device, and an adjustment actuator connected with the variable track device driving unit respectively, and the data processing module is built-in with a track residual life prediction model.

[0018] Further, the composite surface layer is prepared from the following raw materials by weight:

[0019] Nylon mesh skeleton 30-40 parts, glass fiber 20-30 parts, toughness modifier 10-15 parts, and anti-aging agent 5-10 parts.

[0020] Further, in some preferred embodiments, 1-5 parts of microencapsulated self-repairing agent is added to the raw materials of the composite surface layer; the microencapsulated self-repairing agent is a microcapsule with urea-formaldehyde resin as the wall material and dicyclopentadiene (DCPD) as the core material, with a particle size of 50-150 μm.

[0021] Further, the preparation method of the microencapsulated self-repairing agent comprises the following steps: synthesizing a prepolymer by reacting urea with formaldehyde solution at pH=8-9 and 70℃ for 1h; adding the emulsified DCPD oil phase, forming an O / W emulsion under a shear rate of 500 r / min for 10 min; adding 20% ammonium chloride solution to adjust the pH to 3-4, and then reacting at 85℃ for 2h for in-situ polymerization, and then filtering and drying to obtain microcapsule powder.

[0022] Further, the composite surface layer is prepared by a molding process and has a hardness gradient distribution characteristic formed by layering different hardness composite material billets in the mold, specifically:

[0023] Along the cross-sectional direction of the track body, the hardness shows a linear gradient distribution from the track joint center line to the two side edges; the Shore D hardness at the center line is 75D-80D, and the Shore D hardness at the two side edges is 90D-95D, and the hardness gradient change rate is 1.5-2.5D / cm.

[0024] Further, the honeycomb damping layer is a regular hexagonal aluminum honeycomb structure, and the interior of the honeycomb unit of the aluminum honeycomb structure is filled with a shear thickening fluid; the shear thickening fluid is composed of the following components:

[0025] Monodisperse silica nanoparticles as the dispersed phase, with a particle size of 100-300 nanometers;

[0026] And polyethylene glycol as the continuous phase;

[0027] The mass fraction of the silica nanoparticles in the polyethylene glycol carrier liquid is 40%-55%;

[0028] The preparation method of the shear thickening fluid comprises the following steps: directly adding the silica nanoparticles into the polyethylene glycol carrier liquid, mixing at 50-60°C under mechanical stirring for 2-3 hours, and then performing vacuum defoaming treatment to obtain the shear thickening fluid.

[0029] Further, the micro-textured base layer is a #45 steel structure layer, and a micro-textured array is processed on the upper surface of the steel structure layer; the micro-textured array is a periodic array of pits, the geometric shape of the pits is a truncated cone, and when the pit array is combined with the lower layer material of the honeycomb damping layer, a mechanically interlocked interface is formed to enhance the interlayer bonding strength.

[0030] Further, the fiber Bragg grating sensing module comprises a plurality of optical fibers embedded in the track body composite material surface layer through pre-slotted embedding, each optical fiber is engraved with a plurality of fiber Bragg gratings with different center wavelengths, and is used for monitoring multi-point strain distribution data of the track body under the load of the transportation equipment in real time.

[0031] Further, the track residual life prediction model in the data processing module is a hybrid prediction model based on the Miner linear cumulative damage theory and the Paris-Erdogan crack propagation law, and the S-N curve data and crack propagation material constants of the composite material surface layer material are pre-stored; the data processing module performs the following steps for life prediction:

[0032] Step S1: receiving real-time strain / time data collected by the fiber Bragg grating sensing module;

[0033] Step S2: processing the strain / time data by rainflow counting method to extract stress amplitude spectrum and cycle number;

[0034] Step S3: based on the pre-stored S-N curve, the fatigue damage increment in the current time step is calculated by using the Miner linear cumulative damage theory;

[0035] Step S4: accumulating historical fatigue damage, combining the Paris-Erdogan crack propagation law and the material constant to predict the propagation rate of micro-cracks, and outputting the predicted residual service life of the track;

[0036] Step S5: comparing the predicted residual service life of the track with a preset threshold, generating a thrust adjustment instruction signal for the adjustment actuator to control the switching speed and smoothness of the track switching device.

[0037] Further, the track body preparation method is as follows:

[0038] S101: providing a 45 steel plate, and preparing the pit array on the upper surface of the steel plate by using laser surface texturing technology or micro electroforming technology to form the micro-textured base layer;

[0039] S102: placing the regular hexagonal aluminum honeycomb structure on the micro-textured base layer, and filling the shear thickening fluid prepared according to the method of claim 4 into the honeycomb cells of the aluminum honeycomb structure by using a vacuum-assisted infusion process to form the honeycomb damping layer;

[0040] S103: the composite melt of nylon, glass fiber, toughness improver and anti-aging additive is mixed and melted according to a predetermined ratio, and the composite surface layer is integrally formed on the upper surface of the honeycomb damping layer by mold pressing process under the conditions of pressure of 10-15 MPa and temperature of 180-200°C, and the optical fiber with FBG is prepositioned at a predetermined position of the mold cavity before molding, and the bottom of the composite surface layer is effectively infiltrated and mechanically interlocked with the honeycomb damping layer and the pit array of the micro-textured base layer during the molding process, and the track body is obtained after cooling and solidification.

[0041] Compared with the prior art, the present application has the following beneficial effects:

[0042] The track body of the present application adopts a three-layer gradient structure of a composite surface layer, a honeycomb damping layer and a micro-textured base layer to synergistically improve the strength, shock absorption and durability of the track. The composite surface layer provides a surface wear-resistant and load-bearing basis, the honeycomb damping layer absorbs vibration energy, and the micro-textured base layer ensures the overall structural stiffness, solving the problem of insufficient performance of the traditional single structure of the track; the composite surface layer provides a surface wear-resistant and load-bearing basis, the honeycomb damping layer absorbs vibration energy through the honeycomb structure and damping material, and the micro-textured base layer enhances the overall structural strength; the variable track device drives the base to move through the driving unit to realize rapid alignment of the track segments, replacing the traditional manual variable track and greatly improving the variable track efficiency; the closed-loop control equipment monitors the track strain in real time through optical fiber sensing, combines the life prediction model of the data processing module and the adjustment function of the central controller to realize dynamic perception of the track state and intelligent regulation of the variable track parameters.

[0043] The present application forms a hardness gradient from the track joint center line to the two side edges by mold pressing process, so that the joint has a certain flexibility to buffer impact, the edge maintains high hardness to improve the carrying capacity, reduces the stress concentration in the joint area, and prolongs the fatigue life of the track. At the same time, the composite of nylon grid skeleton and glass fiber enhances the tensile and bending resistance of the surface layer, and the anti-aging additive improves the weather resistance in the greenhouse environment. Attached Figure Description

[0044] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0045] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0046] Figure 2 For the present invention Figure 1 The main view.

[0047] Figure 3 This is a schematic diagram of the overall structure of the honeycomb gradient composite structure of the present invention.

[0048] Figure 4 This is a block diagram illustrating the overall principle of the data processing module of the present invention.

[0049] Figure label:

[0050] 101 Track body, 102 Track changing device, 103 Base, 104 Alternate track section, 105 Drive unit, 106 Honeycomb gradient composite structure, 107 Composite material surface layer, 108 Honeycomb damping layer, 109 Microtextured base layer. Detailed Implementation

[0051] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the embodiments of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive. The following description is in conjunction with the accompanying drawings. Figures 1-4 The embodiments of the present invention will be described in detail below.

[0052] Example 1:

[0053] See Figures 1-4 This embodiment discloses a track system for a greenhouse, including a track body 101, a track-changing device 102, and a closed-loop control device. The track body 101 is used to carry transport equipment; the track-changing device 102 is connected to the track body 101 and is used to switch the travel path of the transport equipment; the closed-loop control device is electrically connected to the track body 101 and the track-changing device 102 and is used to monitor the operating status of the track body 101 and control the switching action of the track-changing device 102.

[0054] The track body 101 is a honeycomb gradient composite structure 106, which includes, from top to bottom along the direction perpendicular to the laying plane, a composite material surface layer 107, a honeycomb damping layer 108, and a micro-textured base layer 109; the track changing device 102 includes a base 103, a plurality of alternative track segments 104 arranged on the base 103, and a driving unit 105 connected with the base 103, which is used to drive the base 103 to move so as to align one of the alternative track segments 104 with the track body 101; the closed-loop control device includes a fiber Bragg grating sensing module implanted in the track body 101, a data processing module connected with the sensing module, and a central controller electrically connected with the data processing module, the track changing device 102, and an adjustment actuator connected with the driving unit 105 of the track changing device 102, respectively, and the data processing module is built-in with a track residual life prediction model.

[0055] Further, when the transportation equipment needs to switch the driving path, the driving unit 105 rigidly connected with the base 103 drives the base 103 to move smoothly along the transverse direction perpendicular to the track body 101, thereby driving the plurality of alternative track segments 104 on the base 103 to move synchronously until the target alternative track segment 104 (such as a left / right turning track segment) is completely aligned with the axis of the track body 101, so that the gap between the two can be controlled within ±0.1mm, effectively avoiding the risk of jamming when the wheel set of the transportation equipment passes through the joint; at the same time, an electromagnetic locking assembly can be arranged on the side of the base 103, and after the target alternative track segment 104 is aligned, the locking pin of the electromagnetic locking assembly is inserted into the pre-positioned hole in the ground to rigidly lock the base 103 with the ground, ensuring the structural stability when the transportation equipment passes through.

[0056] In this embodiment, the raw material composition of the composite material surface layer 107 is as follows: 30 parts by weight of nylon grid skeleton, 20 parts by weight of glass fiber, 10 parts by weight of toughness modifier, and 5 parts by weight of anti-radiation and anti-aging additive.

[0057] The toughness modifier is ethylene-vinyl acetate copolymer, such as Elvax® series products (such as Elvax360) of DuPont or Hanol™ A50F of Hanwha. In this embodiment, Elvax360 is preferred, and the content of vinyl acetate is preferably 25%-33%, and the melt index (MI, 190°C / 2.16kg) is preferably 5-15g / 10min, to adapt to the compression molding process.

[0058] Further, the anti-aging additive is a composite system of a hindered amine light stabilizer (HALS) and an ultraviolet absorber (UVA) in a mass ratio of 1:1; wherein the hindered amine light stabilizer can be Tinuvin® 770 (chemical name: bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate) of BASF or Songlight® 7700 of Songwon, and the embodiment preferably Tinuvin® 770; and the ultraviolet absorber can be Tinuvin® 327 (chemical name: 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole) of BASF or Eversorb® 109 of Everlight of Taiwan, and the embodiment preferably Eversorb® 109.

[0059] The above raw materials were put into a double-screw extruder, and after melt mixing at 180°C, the composite material particles were obtained by extrusion and granulation. A molding process was used, and different hardness composite material billets were laid in 5 layers along the cross-sectional direction of the mold cavity. The mold was pressed at a pressure of 10 MPa and a temperature of 180°C for 30 minutes. After molding, a linear hardness gradient distribution was presented along the track joint centerline to the two side edges, wherein the Shore D hardness at the centerline was 75D, and the Shore D hardness at the two side edges (30cm away from the centerline) was 90D.

[0060] wherein the gradient characteristics were calculated by using the hardness gradient change rate formula:

[0061] ;

[0062] wherein, is the hardness gradient change rate (unit: D / cm), is the Shore D hardness of the two side edges of the track (unit: D), is the Shore D hardness at the centerline of the track (unit: D), is the distance from the centerline of the track to the single side edge (unit: cm).

[0063] The specific calculation is as follows:

[0064] Substituting the formula gives:

[0065] that is, the Shore D hardness at the centerline is 75D, and the Shore D hardness at the two side edges (30cm away from the centerline) is 90D, and the hardness gradient change rate is 1.5D / cm.

[0066] The honeycomb damping layer 108 is made of 3003 aluminum alloy foil with a thickness of 0.1 mm, the honeycomb unit is a regular hexagon with a side length of 5 mm and a height of 20 mm, and the shear thickening fluid is composed of monodisperse silica nanoparticles with a particle size of 100 nm (40 parts by mass) and a polyethylene glycol carrier liquid (60 parts by mass). The specific preparation method is as follows: the silica nanoparticles are added to the polyethylene glycol, mixed at a mechanical stirring speed of 300 r / min at 50°C for 2 hours, and then subjected to a degassing treatment in a vacuum drying box at a vacuum degree of -0.1 MPa for 30 minutes to obtain a shear thickening fluid with a viscosity of 500 mPa·s at a shear rate of 1 s -1 1000 s -1 -1, a viscosity of 5000 mPa·s at a shear rate of 1000 s

[0067] Further, the micro-textured substrate layer 109 is made of a #45 steel plate with a thickness of 10 mm and a hardness of 220 HBW after quenching and tempering treatment. A periodic array of dimples is processed on the upper surface of the steel plate by laser surface texturing technology. The dimples have a truncated cone shape with an upper diameter of 500 μm, a lower diameter of 300 μm, a depth of 200 μm, and a center distance of 1000 μm arranged in a square shape. When combined with the honeycomb damping layer 108, the dimple array forms a mechanical interlocking interface with the lower material of the honeycomb damping layer 108.

[0068] In this embodiment, the track changing device 102 includes a base 103, three alternative track segments 104, and a driving unit 105. The three alternative track segments 104 are respectively a first alternative track segment 104, a second alternative track segment 104, and a third alternative track segment 104.

[0069] The base 103 is a Q235 steel welded structure with dimensions of 1500 mm x 800 mm x 300 mm, and is equipped with universal wheels with brakes at the bottom. The three alternative track segments 104 correspond to straight, left turn, and right turn driving paths, respectively, each with a length of 1000 mm and consistent with the cross-sectional dimensions of the track body 101 (200 mm wide and 100 mm high). The driving unit 105 uses a servo motor with a power of 1.5 kW and a rotating speed of 1500 r / min in combination with a ball screw transmission, with a positioning accuracy of ±0.1 mm, to drive the base 103 to move in the transverse direction (perpendicular to the track direction), thereby aligning the alternative track segments 104 with the track body 101.

[0070] Further, in some preferred embodiments, the driving can also be achieved by using a driving motor and a connecting rod, with one end of the connecting rod hinged to the base 103 and the other end hinged to a crank rod fixed on the output shaft of the driving motor.

[0071] In the embodiment, the fiber Bragg grating sensing module includes 6 optical fibers, which are embedded in the composite surface layer 107 by pre-slotted embedding. Each optical fiber is engraved with 5 fiber Bragg gratings with different center wavelengths, the center wavelengths are 1520 nm, 1530 nm, 1540 nm, 1550 nm and 1560 nm respectively, the grating length is 10 mm, and the interval is 500 mm. The FBG demodulator with resolution of 1 pm and sampling frequency of 100 Hz is used to collect wavelength change data in real time, and the wavelength change is converted to strain data through strain conversion formula subsequently.

[0072] The data processing module is built-in with a hybrid prediction model based on Miner linear cumulative damage theory and Paris-Erdogan crack propagation law, and the S-N curve data of the composite surface layer 107 material are pre-stored, the stress ratio , the fatigue limit , the coefficient , the index m=5 and the crack propagation material constant . The specific data processing steps are as follows:

[0073] The wavelength data collected by the FBG sensing module is received, and the strain calculation formula is used:

[0074] ;

[0075] Among them, is the track material strain (unit: με, microstrain), is the current monitoring wavelength of FBG (unit: nm), is the initial wavelength of FBG (unit: nm), is the FBG strain sensitivity coefficient (unit: 1 / με); in the embodiment, wherein .

[0076] In actual application, if the monitoring wavelength is substituted into the formula, we get:

[0077] Through this method, 1.8x10 5 points of 30-minute strain / time data can be obtained.

[0078] Further, the data processing module is built-in with a hybrid prediction model based on Miner theory and Paris-Erdogan law, and stores the S-N curve of the composite material and the crack propagation constant. The specific calculation steps are as follows:

[0079] S-N curve: Among them, is the stress amplitude (unit: MPa), Fatigue life (unit: cycle) , Material constant.

[0080] Crack propagation constant: Wherein Crack propagation rate (unit: mm / cycle) Stress intensity factor range (unit: MPa·m 1 / 2 ) Crack length (unit: mm) Cycles.

[0081] In practical application:

[0082] Step S1: convert wavelength change to strain, obtain 30 minutes strain / time data (1.8×10 5 points);

[0083] Step S2: stress amplitude spectrum extraction, rain flow counting method to process data, get stress amplitude spectrum: 20 MPa corresponds to 1000 cycles, 30 MPa corresponds to 500 times, 40 MPa corresponds to 200 times;

[0084] Step S3: Miner theory cumulative damage calculation:

[0085] ;

[0086] Wherein, Cumulative damage value, When the material fails, The actual number of cycles under the Stress amplitude, Fatigue life corresponding to the Stress amplitude, derived from . .

[0087] In practical application: calculate the fatigue life under each stress, (Simplified value), (Simplified value);

[0088] Substitute the formula:

[0089] .

[0090] Step S4: Paris law residual life prediction:

[0091] Residual life (cycle):

[0092] ;

[0093] Wherein, is the current crack length (unit: mm), is the critical crack length (unit: mm), is the remaining cycle number.

[0094] The specific calculation is as follows:

[0095] The initial crack is known , the current , the critical , the remaining cycle number is obtained by substituting the formula 1.2x10 6 times;

[0096] Run 1000 times per day .

[0097] Step S5: actuator thrust adjustment: adjust the actuator thrust according to the remaining life: >365 days thrust 500N (speed 50mm / s); 30-365 days thrust 300N (speed 30mm / s); ≤30 days thrust 200N (speed 20mm / s) and pre-warning.

[0098] Further, a Siemens S7-1200 PLC is used to communicate with the data processing module through Ethernet, and outputs a 4-20mA signal to control the electric push rod actuator (adjusting actuator).

[0099] Further, in order to further verify the track performance, in the Taber wear test, the wear amount of the traditional steel track is 80mg / 1000 turns, and the wear amount of the track of the embodiment is 15mg / 1000 turns, which is improved by 7 times; When the transportation equipment (500kg, 1m / s) is running, the vibration acceleration of the traditional track is 15m / s², and the vibration acceleration of the track of the embodiment is 3m / s², which is reduced by 80% compared with the traditional track; After the accelerated fatigue test (equivalent to 2000 days), there is no crack, and the traditional track appears a 2mm deep crack. The rail changing time is 15 seconds (the efficiency is improved by 20 times); In 180 days of monitoring, the life prediction deviation is <5%, the track life is more than 5 years, the rail changing efficiency is improved by 20 times, the vibration noise is reduced by 80%, more than 10 potential failures are avoided, and the maintenance cost is reduced by 60%.

[0100] Example 2:

[0101] The embodiment is basically the same as example 1, and the difference is that in the embodiment, the composite surface layer 107: the raw materials are nylon grid skeleton 35 parts, glass fiber 25 parts, toughness modifier 12 parts, and anti-radiation anti-aging additive 7 parts by weight. The mold pressing pressure is 12MPa, and the temperature is 190℃.

[0102] The hardness gradient is calculated, and it is known that: , and the following is obtained:

[0103] i.e. the center line 77D, the edge 92D, and the gradient change rate 2D / cm.

[0104] Further, in the present embodiment, the shear thickening fluid contains 47.5 parts by mass of silica with a particle size of 200 nm and 52.5 parts by mass of polyethylene glycol, is stirred at 55°C for 2.5 hours, and has a viscosity of 800 mPa·s at 1 s -1 viscosity 800 mPa·s, 1000 s -1 viscosity 8000 mPa·s.

[0105] Further,

[0106] S-N curve parameters: , a certain stress , the fatigue life:

[0107] ;

[0108] Crack propagation constant: , the current crack , the critical , by formula integration, the remaining cycle number is about 1.3 x 10 6 times, running at 1000 times per day, the remaining life is 1300 days.

[0109] The wear resistance test is carried out, the wear amount is 12 mg / 1000 turns, which is better than example 1, the vibration acceleration is 2.5 m / s², the model prediction deviation is <4%, the precision is higher than example 1, the variable orbit time is 14 seconds, and the remaining life prediction is more accurate.

[0110] Example 3:

[0111] The present embodiment is basically the same as example 1, and the difference lies in that, in the present embodiment, the composite material surface layer 107: the raw materials are 40 parts by weight of nylon grid skeleton, 30 parts by weight of glass fiber, 15 parts by weight of toughness modifier, and 10 parts by weight of anti-radiation and anti-aging additives. The mold pressing pressure is 15 MPa, and the temperature is 200°C.

[0112] Hardness gradient calculation, known: , by substitution: i.e. the center line 80D, the edge 95D, and the gradient change rate 2.5D / cm.

[0113] Honeycomb damping layer 108: shear thickening fluid contains 55 parts by mass of silica with a particle size of 300 nm and 45 parts by mass of polyethylene glycol, is stirred at 60°C for 3 hours, and has a viscosity of 1000 mPa·s at 1 s -1 viscosity 1000 mPa·s, 1000 s -1 viscosity 10000 mPa·s.

[0114] Further,

[0115] S-N curve parameters: , certain stress , fatigue life:

[0116] ;

[0117] Crack propagation constant: , current crack , critical , by formula integral remaining cycle number is about 1.6*10 6 , according to 1000 times per day operation, the remaining life is 1500 days.

[0118] Test, wear 10mg / 1000 turns for optimal; vibration acceleration 2m / s², compared with embodiment 1, reduced by 87%; model prediction deviation <3% (highest accuracy), variable orbit time 13 seconds, remaining life more than 1500 days.

[0119] In the actual use of the application, the structure of the traditional single metal or simple composite track is broken through, a three-layer cooperative structure of a composite surface layer from top to bottom, a honeycomb damping layer and a micro-textured base layer is designed, and a function integrated structure of wear-resistant bearing, vibration and noise reduction structure stability is realized. Gradient performance matching is realized, the composite surface layer provides surface wear resistance and aging resistance, the honeycomb damping layer absorbs vibration energy, and the micro-textured base layer ensures the rigidity of the overall structure, solves the contradiction between the traditional track rigidity and poor damping, wear resistance and easy corrosion; More importantly, the application realizes the purpose of interlayer mechanical interlocking, the upper surface of the micro-textured base layer (#45 steel) is processed with a periodic truncated cone pit array, and a mechanical interlocking interface is formed with the lower material of the honeycomb damping layer, the interlayer bonding strength is increased by more than 30% than the traditional bonding method, and the delamination failure is effectively avoided.

[0120] In the application, different hardness blanks are layered and laid through a molding process, linear hardness gradient distribution of the track joint center line to both sides of the edge is realized, the center line Shore D hardness is 75D-80D, the edge is 90D-95D, the gradient change rate is 1.5-2.5D / cm, the flexible buffer impact at the joint, the high hardness bearing at the edge, the stress concentration at the joint is reduced, and the fatigue life is prolonged by more than 3 times than that of the traditional track; at the same time, nylon grid skeleton and glass fiber are used as reinforced base materials, toughness improver is added to improve impact resistance, and hindered amine light stabilizer and ultraviolet absorber 1:1 are compounded to improve the anti-aging performance by 2 times than that of ordinary composite materials in a greenhouse high temperature and high humidity environment, the service life is more than 5 years, and the service life of the traditional metal track is only 1-2 years.

[0121] Further, in the application, the aluminum honeycomb unit is filled with STF, monodisperse silica nanoparticles 100-300 nm, and polyethylene glycol carrier liquid in a specific ratio, and the particle mass fraction is 40%-55%. STF is in a low viscosity state under low shear rate, and the viscosity rises sharply under high shear rate, such as vibration of transportation equipment. The vibration energy absorption efficiency is improved by 80% compared with traditional rubber damping layer, and the vibration acceleration of transportation equipment is reduced from 15 m / s² to 2-3 m / s² during operation. At the same time, by pre-slotted embedding method, multiple optical fibers engraved with FBG of different center wavelengths are implanted in the surface layer of the composite material, real-time multi-point strain data of the track are collected, the monitoring accuracy is improved by one order of magnitude compared with traditional electric sensors, and the sensors are not disturbed by high temperature and humidity and much dust in the greenhouse. The fatigue damage increment is calculated by Miner linear cumulative damage theory combined with S-N curve based on the stress amplitude spectrum and cycle number extracted by rain flow counting method. The micro-crack propagation rate is predicted by combining Paris-Erdogan crack propagation law, and the residual service life is accurately output with a prediction deviation of less than 5%. The residual life is compared with the preset threshold value, and the generated adjustment actuator thrust command controls the switching speed of the variable orbit device, such as speed of 50 mm / s when the life is greater than 365 days, speed of 20 mm / s when the life is less than or equal to 30 days, and warning, to avoid sudden failure.

[0122] The application adopts an integrated forming process, the track body is formed by three steps of laser processing of a micro-textured base, vacuum pouring of a honeycomb damping layer, and fiber embedding of a composite material surface layer, effective infiltration and mechanical interlocking of the surface layer, the damping layer and the base are realized in the forming process, the joint jamming problem of a traditional assembled track is avoided, and the structural stability is improved.

[0123] Embodiment 4

[0124] This embodiment is further optimized on the basis of embodiment 1. In this embodiment, 1-5 parts of microencapsulated self-repairing agent are further added to the raw material of the composite material surface layer 107; the microencapsulated self-repairing agent is a microcapsule with urea-formaldehyde resin as a wall material and dicyclopentadiene (DCPD) as a core material, and the particle size is 50-150 μm.

[0125] Further, the preparation method of the microencapsulated self-repairing agent comprises the following steps:

[0126] The urea and formaldehyde solution are reacted at pH=8-9 and 70℃ for 1h to synthesize a prepolymer;

[0127] The emulsified DCPD oil phase is added, and an O / W emulsion is formed by emulsifying for 10 min under a shear rate of 500 r / min;

[0128] The pH is adjusted to 3-4 by adding 20% ammonium chloride solution, and in-situ polymerization is carried out by heating to 85℃ for 2h. After filtration and drying, a microcapsule powder is obtained.

[0129] In actual use, 3 parts by weight of microencapsulated self-repairing agent is added to the composite surface layer material of Example 1, and the molding process parameters remain unchanged.

[0130] The above microencapsulated self-repairing agent is added to the composite surface layer, and the following performance tests are conducted:

[0131] 1) Pre-cracking: A three-point bending test is used to pre-crack the track specimen, and the crack depth reaches 0.5 mm.

[0132] 2) Self-repairing process: The pre-cracked specimen is placed in a 60°C environment for 24 hours for self-repairing. This temperature simulates the high temperature period in the greenhouse environment, which is conducive to the polymerization reaction of the dicyclopentadiene (DCPD) core material.

[0133] 3) Performance evaluation:

[0134] Crack healing: Through microscopic observation, the repaired crack is basically healed, and the crack trace is difficult to distinguish with the naked eye.

[0135] Mechanical property recovery rate: The mechanical properties of the repaired specimen are tested, and compared with the undamaged specimen, the mechanical property recovery rate is more than 85%. The specific test items include bending strength, tensile strength, etc., all of which use industry standard test methods.

[0136] The track of this embodiment is compared with the traditional track (without self-repairing function). The traditional track, after appearing the same 0.5 mm deep crack, runs under the same load condition of 500 kg transportation equipment and 1 m / s running speed, and the crack rapidly expands to the critical length (5 mm) within 50 days, resulting in track failure. However, the track of this embodiment can rely on the microencapsulated self-repairing agent to repair itself after appearing micro-cracks. According to theoretical calculation and simulation test, it is expected that the service life of the track can be extended by 40% based on the original basis. This not only significantly reduces the risk of production interruption caused by sudden failure of the track, but also greatly reduces the maintenance frequency and the operating cost of the greenhouse.

[0137] Slow-release microspheres are added to the DCPD core material, with a particle size of 10-20 μm and a wall material of polylactic acid. When the crack is small, only the outer DCPD rapidly polymerizes, and the repair is completed within 6 hours. If the crack continues to expand, the polylactic acid microspheres break under stress, releasing the inner DCPD, achieving phased repair and avoiding incomplete repair caused by insufficient single release amount.

[0138] The embodiment breaks through the limitations of traditional passive maintenance and realizes active and autonomous repair of track micro-cracks. Embodiments 1-3 rely on artificial inspection, passive mode of replacement / repair in later stage: after the traditional metal track appears micro-cracks, if not found in time, it will quickly expand under the action of transportation load cycle, and within 50 days, a 0.5 mm deep crack can develop to a critical failure state, and a 5 mm deep crack can lead to transportation interruption. Although embodiments 1-3 can monitor cracks and give early warnings through FBG sensing modules, artificial intervention for maintenance is still needed, and production stoppage during maintenance cannot be avoided. The embodiment adds microencapsulated self-repairing agents with urea-formaldehyde resin wall material and dicyclopentadiene (DCPD) core material in the composite surface layer to build an active mechanism for crack triggering and autonomous repair.

[0139] When the track produces micro-cracks due to fatigue, such as 0.5 mm deep cracks caused by repeated action of transportation load, the microcapsules on the damage path will be squeezed and broken during crack propagation, with a particle size of 50-150 μm, which is suitable for the base material of the composite surface layer. After the microcapsules are broken, the DCPD core material is released and autonomously polymerizes at a greenhouse environment temperature of about 60°C to fill the crack gap. Within 24 hours, the crack can be healed to the extent that it is not visible to the naked eye, eliminating the need for artificial maintenance and solving the industry pain point of production stoppage for maintenance after crack warning.

[0140] The embodiment selects urea-formaldehyde resin as the microcapsule wall material, which has a temperature resistance (long-term resistance to 60-80°C, matching the high-temperature environment of the greenhouse), a mechanical strength close to that of the nylon grid skeleton / glass fiber base material, and is suitable for the composite surface layer, avoiding a decrease in the strength of the track surface layer due to differences in the properties of the wall material. The microcapsule particle size is controlled to be 50-150 μm, which is smaller than the molding precision of the composite surface layer and is compatible with particles below 200 μm in the molding process, and can ensure that the microcapsules are effectively squeezed and broken during crack propagation, avoiding the contradiction between too small particle size that does not break and too large particle size that affects molding.

[0141] The microcapsules are prepared by in-situ polymerization, and the powder product can be directly mixed with nylon, glass fiber and other raw materials without changing the original double-screw extrusion and molding process, avoiding additional process costs. The microcapsules are uniformly dispersed in the composite surface layer, and the shear emulsification at 500 r / min ensures uniform particle size, does not affect the embedding stability of the FBG optical fiber, and does not interfere with the strain monitoring signal, realizing the synergistic coexistence of the self-repairing function and the state monitoring function.

[0142] The composite track without self-repairing function in the prior art will fail within 50 days if it has a 0.5 mm deep crack and is not repaired; while the track of Example 4 can be repaired by self-repairing under the same crack condition, the service life is prolonged by 40% on the basis of the original 5 years, i.e. the service life is additionally increased by 2 years, and the total service life is more than 7 years; the maintenance cost is reduced compared with Example 1, as frequent manual inspection and repair are not needed; the failure of the track in the prior art due to cracks will cause interruption of transportation, and the loss of each interruption is about ten thousand yuan; the self-repairing function of Example 4 can avoid such sudden failure, and ensure the continuous operation of greenhouse seedling transplanting, water and fertilizer transportation and the like.

[0143] The present embodiment is not a simple improvement of the prior Examples 1-3, but aims at the unsolved technical blank of passive maintenance of track micro-cracks, and cooperatively designs the micro-encapsulated self-repairing agent and the composite track system, so that the damage self-repairing is first realized in the field of greenhouse track, the track system is upgraded from the monitoring and early warning level to the active protection level, and a more complete and reliable technical solution is formed.

[0144] The self-repairing agent of the present embodiment is only added to the surface layer of the composite material, but the track is a three-layer structure of the surface layer of the composite material, the honeycomb damping layer and the micro-textured base layer, and in actual use, damages such as shear failure of the honeycomb damping layer and interfacial peeling of the micro-textured base layer and the damping layer may occur, leading to the overall failure of the track, therefore, in some preferred embodiments, the elastic microcapsules are mixed in the shear thickening fluid (STF) filled in the aluminum honeycomb unit, the wall material of the elastic microcapsules is polyurethane, and the core material is a silane-modified polyether; when the honeycomb unit is broken due to vibration shear, the polyurethane wall material is broken under the action of shear force, the core material is released and reacts with the silicon dioxide nanoparticles in the STF, forming an elastic gel to block the leakage channel and restore the damping performance of the STF, and the damping coefficient recovery rate is more than 90% through testing.

[0145] Further, in the array of pits in the micro-textured base layer, the micro-encapsulated adhesive is pre-coated, the wall material is polycaprolactone, and the core material is an epoxy resin and a latent curing agent, and the ratio is 1:1; when interlayer peeling occurs due to vibration, the polycaprolactone wall material is broken under the action of peeling stress, the epoxy resin contacts and reacts with the curing agent to re-bond the interface, and the interlayer bonding strength recovery rate is more than 80%.

[0146] Further, in some preferred embodiments, 0.1%-0.3% of a temperature-sensitive fluorescent dye such as a rhodamine B derivative is mixed in the core material of the microcapsules, which emits red fluorescence above 60℃ and has no fluorescence at room temperature; after the repair is completed, the central controller triggers the micro fluorescent detector above the track; in actual use, the micro fluorescent detector is installed on the transportation equipment and moves with the equipment to scan, the repair range is determined by the fluorescence intensity, and the fluorescent coverage area is equal to the repair area; if there is no fluorescence in a certain area, it indicates that the repair is not complete, and the repair condition is quickly detected.

[0147] Further, in some preferred embodiments, the wall material adopts a compostable polyhydroxyalkanoate (PHA), the compostable polyhydroxyalkanoate (PHA) has a tensile strength of 30-40 MPa, which is close to that of urea-formaldehyde resin, and can be naturally degraded in soil, with a degradation rate of 90% in 180 days; after the track is scrapped, the microcapsules will not cause soil pollution

[0148] Although the preferred embodiments of the present application have been described, those skilled in the art who understand the basic inventive concept can make further changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0149] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. It should be pointed out that any modification, equivalent replacement and improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A track system for a greenhouse, characterized in that The utility model relates to a track system for transporting equipment, comprising: a track body for carrying the transporting equipment; a track switching device connected to the track body for switching the running path of the transporting equipment; a closed-loop control device electrically connected to the track body and the track switching device for monitoring the running state of the track body and controlling the switching action of the track switching device; wherein the track body is a honeycomb gradient composite structure, which comprises, from top to bottom along the direction perpendicular to the laying plane, a composite material surface layer, a honeycomb damping layer and a micro-textured base layer; the track switching device comprises a base, a plurality of alternative track segments arranged on the base and a driving unit connected to the base, the driving unit being used to drive the base to move so as to align one of the alternative track segments with the track body; the closed-loop control device comprises a fiber Bragg grating (FBG) sensing module embedded in the track body, a data processing module connected to the sensing module and a central controller electrically connected to the data processing module, the track switching device and an adjusting actuator connected to the driving unit of the track switching device, the data processing module being internally provided with a track residual life prediction model; the honeycomb damping layer is a regular hexagonal aluminum honeycomb structure, the interior of the honeycomb cells of the aluminum honeycomb structure being filled with a shear thickening fluid; the shear thickening fluid is composed of: monodisperse silica nanoparticles with a particle size of 100-300 nm as the dispersed phase; and polyethylene glycol as the continuous phase; the mass fraction of the silica nanoparticles in the polyethylene glycol is 40%-55%; the preparation method of the shear thickening fluid comprises the following steps: directly adding the silica nanoparticles to the polyethylene glycol, mixing at 50-60°C under mechanical stirring for 2-3 hours, and then performing vacuum degassing treatment to obtain the shear thickening fluid; the preparation method of the track body is as follows: S101: providing a #45 steel plate, preparing a pit array on the upper surface of the steel plate by using a laser surface texturing technology or a micro electroforming technology to form the micro-textured base layer; S102: placing a regular hexagonal aluminum honeycomb structure on the micro-textured base layer, filling the shear thickening fluid prepared by the preparation method of the shear thickening fluid into the interior of the honeycomb cells of the aluminum honeycomb structure by using a vacuum-assisted infusion process to form the honeycomb damping layer; S103: integrally forming the composite material surface layer on the upper surface of the honeycomb damping layer by using a molding process under the conditions of a pressure of 10-15 MPa and a temperature of 180-200°C, and prepositioning an FBG-written optical fiber at a predetermined position in the mold cavity before molding, and realizing effective infiltration and mechanical interlocking between the bottom of the composite material surface layer and the honeycomb damping layer, between the bottom of the honeycomb damping layer and the pit array of the micro-textured base layer during the molding process, and obtaining the track body after cooling and solidification.

2. A track system for a greenhouse according to claim 1, characterized in that: The composite surface layer is prepared from the following raw materials by weight: nylon mesh skeleton 30-40 parts, glass fiber 20-30 parts, toughness modifier 10-15 parts, and anti-aging additive 5-10 parts.

3. A track system for a greenhouse according to claim 2, characterized in that: The composite surface layer is prepared by a molding process and has a hardness gradient distribution characteristic formed by layering different hardness composite billets in the mold. Along the cross-sectional direction of the track body, the hardness linearly increases from the center line of the track joint to the two side edges; the Shore D hardness at the center line is 75D-80D, and the Shore D hardness at the two side edges is 90D-95D, and the hardness gradient change rate is 1.5-2.5D / cm.

4. A track system for a greenhouse according to claim 1, characterized in that: The micro-textured base layer is a #45 steel structure layer.

5. A track system for a greenhouse according to claim 1, characterized in that: The fiber Bragg grating sensing module includes a plurality of optical fibers embedded in the composite surface layer of the track body by pre-slot embedding, each optical fiber is engraved with a plurality of fiber Bragg gratings with different center wavelengths, and is used for real-time monitoring of multi-point strain distribution data of the track body under the load of the transportation equipment.

6. A track system for a greenhouse according to claim 1, characterized in that: The track residual life prediction model in the data processing module is a hybrid prediction model based on the Miner linear cumulative damage theory and the Paris-Erdogan crack propagation law, and the S-N curve data and crack propagation material constants of the composite surface layer material are pre-stored; the data processing module performs the following steps for life prediction: Step S1: receiving real-time strain / time data collected by the fiber Bragg grating sensing module; Step S2: processing the strain / time data by rainflow counting method to extract stress amplitude spectrum and cycle number; Step S3: based on the pre-stored S-N curve, the fatigue damage increment in the current time step is calculated by using the Miner linear cumulative damage theory; Step S4: accumulate historical fatigue damage, and combine Paris-Erdogan crack propagation law and material constant to predict the expansion rate of micro-cracks, and output the predicted residual service life of the track; Step S5: compare the predicted residual service life of the track with the preset threshold, generate thrust adjustment instruction signal for the adjustment actuator, and control the switching speed and smoothness of the track switching device.

7. A track system for a greenhouse according to claim 2 or 3, characterized in that: The raw materials of the composite surface layer also add microencapsulated self-repairing agent 1-5 parts.

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