High-water-absorption moisturizing type flexible light grounding module and preparation method thereof

Abstract

The invention relates to a high-water-absorption moisturizing type flexible light grounding module and a preparation method thereof, the high-water-absorption moisturizing type flexible light grounding module comprises a plurality of connecting conductors and a plurality of grounding units distributed along a straight line, the connecting conductors are used for connecting adjacent grounding units or connecting horizontal grounding bodies and grounding units buried in a grounding trench, and each grounding unit comprises a graphite wire woven mesh sleeve. The graphite wire woven mesh sleeve wraps a moisture absorption block, and the connecting conductor and the graphite wire woven mesh sleeve as well as the connecting conductor and the horizontal grounding body are connected through clamps. According to the invention, the water absorption and moisture retention performance of the grounding module is improved.

Description

Technical Field

[0001] The invention relates to the technical field of power system grounding, in particular to a highly water-absorbent and moisture-keeping flexible lightweight grounding module and a preparation method thereof. Background Art

[0002] The grounding module is a grounding resistance reduction material used to improve the grounding system. Its main function is to reduce the contact resistance by increasing the contact area with the soil, thereby improving the performance of the grounding system.

[0003] Existing grounding modules are usually made of conductive concrete wrapped around a galvanized steel core. Conductive concrete will form a certain number of pore structures during the solidification process, thereby producing a certain water absorption and moisture retention effect, but the number of pore structures directly affects the mechanical properties of the conductive concrete. The more pore structures a grounding module has, the worse its mechanical properties are and the easier it is to break. In order to ensure the mechanical properties of the grounding module and extend its service life, the amount of its pore structure is usually controlled, but this will result in poor water absorption and moisture retention performance of the grounding module, making it difficult to maintain a stable resistance value in arid environments. Summary of the invention

[0004] In order to solve the problem in the prior art that the grounding module has poor water absorption and moisture retention performance while ensuring the mechanical properties of the grounding module, the present invention provides a highly water absorption and moisture retention flexible lightweight grounding module and a preparation method thereof, which improves the water absorption and moisture retention performance of the grounding module.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a highly water-absorbent and moisture-retaining flexible lightweight grounding module, comprising a plurality of connecting conductors and a plurality of grounding units distributed along a straight line, the connecting conductors being used to connect adjacent grounding units or to connect a horizontal grounding body buried in a grounding trench and a grounding unit, the grounding unit comprising a graphite wire mesh sleeve, the graphite wire mesh sleeve being wrapped with a moisture-absorbing block, the connecting conductor and the graphite wire mesh sleeve as well as the connecting conductor and the horizontal grounding body being connected by a clamp.

[0006] As a further optimization of the invention of a highly water-absorbent and moisture-retaining flexible lightweight grounding module: the graphite wire mesh sleeve has a wrapping portion and a reduced diameter portion, the wrapping portion is used to wrap the moisture-absorbing block, the reduced diameter portion is used to connect with the connecting conductor, and the mesh holes of the wrapping portion are larger than the mesh holes of the reduced diameter portion.

[0007] The technical solution adopted by the present invention to solve the above technical problems is: a preparation method, which comprises the following steps:

[0008] S1, making a hygroscopic mixture;

[0009] S2, pressing the hygroscopic mixture into a hygroscopic block;

[0010] S3, weaving a graphite wire mesh sleeve outside the moisture absorbing block to obtain a grounding unit;

[0011] S4. Connect multiple grounding units in series through connecting conductors to obtain a grounding module.

[0012] As a further optimization of the preparation method of the invention: the hygroscopic mixture is composed of the following raw materials in weight percentage: 15-20% of super absorbent resin, 25-30% of modified bentonite, 30-35% of expandable graphite, 10-15% of polylight balls and 5-10% of chopped glass fibers.

[0013] As a further optimization of the preparation method of the invention: the specific steps of preparing the hygroscopic mixture are:

[0014] S1-1, treating the resin to obtain a highly absorbent resin;

[0015] S1-2, modifying bentonite to obtain modified bentonite;

[0016] S1-3, mixing highly water-absorbent resin, modified bentonite, expandable graphite, polylight balls and chopped glass fibers to obtain the hygroscopic mixture.

[0017] As a further optimization of the preparation method of the invention: the specific steps of treating the resin to obtain the highly absorbent resin are:

[0018] S1-1-1, dissolving polyvinyl pyrrolidone in deionized water to obtain a polyvinyl pyrrolidone mixed solution;

[0019] S1-1-2, dispersing nano silver powder in a polyvinyl pyrrolidone mixed solution to obtain a nano silver powder dispersion;

[0020] S1-1-3, dissolving sodium acrylate monomer in deionized water to obtain a sodium acrylate solution, mixing the sodium acrylate solution and the nano silver powder dispersion and transferring the mixture to a reaction kettle;

[0021] S1-1-4, adding an initiator and a cross-linking agent to a reaction kettle in sequence to obtain a reaction solution, adjusting the pH value of the reaction solution, and then performing a polymerization reaction to obtain a reaction product;

[0022] S1-1-5. The reaction product is washed, filtered, dried and crushed in sequence to obtain a highly absorbent resin.

[0023] As a further optimization of the preparation method of the invention: the specific steps of modifying the bentonite to obtain the modified bentonite are:

[0024] S1-2-1, pre-treating bentonite;

[0025] S1-2-2, dissolving hexadecyltrimethylammonium bromide in deionized water to obtain a hexadecyltrimethylammonium bromide solution, and adding the pretreated bentonite to the hexadecyltrimethylammonium bromide solution to react to obtain a mixed solution;

[0026] S1-2-3, centrifuging the mixed solution to obtain a precipitate;

[0027] S1-2-4. Wash, dry and grind the precipitate in sequence to obtain modified bentonite.

[0028] As a further optimization of the preparation method of the invention: in the process of pressing the hygroscopic mixture to obtain the hygroscopic block, the temperature is 20-35°C, the pressing pressure is 8-12MPa, the pressing time is 10-15min, and the holding time is 3-5min.

[0029] As a further optimization of the preparation method of the invention: in the process of weaving the graphite wire mesh sleeve outside the hygroscopic block, the weaving speed is 20-40r / min, the weaving angle is 45-60°, the weaving tension is 5-10N, the weaving thickness is 2-5mm, and the wire diameter of the graphite wire mesh sleeve is 0.5-1.5mm.

[0030] As a further optimization of the invention preparation method: the surface of the graphite wire mesh sleeve is sprayed with a graphite-based binder, and the spraying amount is 50-100 g / m 2 .

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention provides a plurality of connecting conductors and a plurality of grounding units distributed along a straight line. The connecting conductors are used to connect adjacent grounding units or to connect a horizontal grounding body buried in a grounding trench and a grounding unit. The grounding unit includes a graphite wire mesh sleeve, which is wrapped with a hygroscopic block. The graphite wire mesh sleeve reduces the grounding resistance while reducing the risk of the hygroscopic block being broken, so as to facilitate transportation in complex terrain or remote areas. The surface of the graphite wire mesh sleeve has mesh holes, so as to facilitate the contact between the hygroscopic block and the soil, thereby improving the moisturizing effect and further reducing the grounding resistance. The hygroscopic block can absorb water and retain moisture, and can maintain a stable grounding resistance even under drought conditions. Moreover, the shape and size of the hygroscopic block can be more flexibly selected during processing, so as to further ensure the water absorption and moisturizing effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the structure of the present invention;

[0034] Figure 2 It is a schematic diagram of coordination between the first U-shaped frame, the second U-shaped frame, the horizontal grounding body and the connecting conductor;

[0035] Figure 3It is a schematic diagram of the coordination between the second U-shaped frame and the connecting conductor;

[0036] Markings in the figure: 1. grounding trench, 2. horizontal grounding body, 3. connecting conductor, 4. clamp, 5. graphite wire mesh, 6. moisture absorbing block, 7. first U-shaped frame, 8. second U-shaped frame, 9. first fastening bolt, 10. second fastening bolt, 11. first connecting hole. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is further elaborated in detail below in conjunction with specific embodiments. The parts that are not described and disclosed in detail in the following embodiments of the present invention should be understood as the prior art known or should be known to those skilled in the art, such as how the graphite wire mesh 5 is woven, what is the grounding trench 1, what are the horizontal grounding body 2 and the connecting conductor 3, the specific material of the anti-corrosion layer, etc.

[0038] A highly water-absorbent and moisture-retaining flexible and lightweight grounding module, such as Figure 1 As shown, it includes several connecting conductors 3 and multiple grounding units distributed along a straight line. The connecting conductors 3 are used to connect adjacent grounding units or connect the horizontal grounding body 2 buried in the grounding trench 1 and the grounding unit. The grounding unit includes a graphite wire mesh 5, and the graphite wire mesh 5 is wrapped with a hygroscopic block 6. The surface of the graphite wire mesh 5 is soft and has a resilient property. The effective contact area with the soil is large, which reduces the grounding resistance while reducing the risk of the hygroscopic block 6 breaking, and is convenient for transportation in complex terrain or remote areas; the surface of the graphite wire mesh 5 has mesh holes, which is convenient for the hygroscopic block 6 to contact with the soil, improve the moisturizing effect and further reduce the grounding resistance. The hygroscopic block 6 can absorb water and keep moisture, and can maintain a stable grounding resistance even under drought conditions. The hygroscopic block 6 is pressed and formed by super absorbent resin, modified bentonite, expanded graphite with high conductivity rich in microporous structure, polylight balls and chopped fibers. The material of the hygroscopic block 6 is the existing technology in the field, and no more details are given here.

[0039] The connecting conductor 3 and the graphite wire mesh 5 and the connecting conductor 3 and the horizontal grounding body 2 are connected by a clamp 4. Since a plurality of grounding units are arranged between the horizontal grounding bodies 2, and each grounding unit is connected by a connecting conductor 3, compared with the traditional method of wrapping conductive concrete outside the galvanized steel core body, the shape and size of the hygroscopic block 6 in the grounding unit of the present invention can be more flexibly selected during processing, and no longer be restricted by the galvanized steel core body. No matter what shape of the hygroscopic block 6 is processed, the hygroscopic block 6 can be wrapped with a graphite wire mesh 5, and can be changed to a more suitable size according to actual needs; and the grounding units in the present invention are connected by connecting conductors 3. Compared with the traditional method of wrapping conductive concrete outside the galvanized steel core body, the hygroscopic block 6 in the grounding unit has a larger surface area under the same volume, and the effect of water absorption and moisture retention is enhanced. In this embodiment, the depth of the grounding unit buried in the grounding trench 1 is 0.8-1.0m, and the grounding unit can be buried vertically or horizontally. The cross section of the hygroscopic block 6 is set to be circular, and the cross section of the connecting conductor 3 is set to be rectangular. In order to ensure the water absorption and moisturizing effect, the cross-sectional radius of the moisture absorption block 6 is greater than the cross-sectional length of the connecting conductor 3 .

[0040] The graphite wire mesh sleeve 5 has a wrapping part and a reduced diameter part. The wrapping part is used to wrap the hygroscopic block 6. The wrapping part ensures that the hygroscopic block 6 can contact with the soil, reducing the risk of the hygroscopic block 6 breaking; the reduced diameter part is used to connect with the connecting conductor 3. Since the mesh holes of the reduced neck part are not supported by the hygroscopic block 6, the mesh holes of the wrapping part are larger than the mesh holes of the reduced diameter part. In this way, the reduced diameter part not supported by the hygroscopic block 6 can further store moisture and reduce the volatilization of moisture.

[0041] The traditional grounding module has poor corrosion resistance and short service life. In an environment with strong soil corrosion, there is a potential difference between the galvanized steel core and the external covering material, namely the conductive concrete, which will form galvanic corrosion at the interface. This potential difference can form a primary battery reaction in the soil solution to generate corrosion current, thereby accelerating the corrosion of the galvanized steel core. Therefore, the surface of the graphite wire mesh sleeve 5 is coated with an anti-corrosion layer.

[0042] like Figure 2 and Figure 3As shown, the clamp 4 includes a first U-shaped frame 7 that can be buckled on the horizontal grounding body 2 and a second U-shaped frame 8 that can be buckled on the connecting conductor 3. When the first U-shaped frame 7 of the clamp 4 is in use, the bottom of the first U-shaped frame 7 contacts the blocking surface of the horizontal grounding body 2, the second U-shaped frame 8 is located between the two side portions of the first U-shaped frame 7, and the two side portions of the second U-shaped frame 8 are against the horizontal grounding body 2, and the two side portions of the second U-shaped frame 8 are in contact with the connecting conductor 3. At this time, there is a gap between the bottom of the second U-shaped frame 8 and the connecting conductor 3. A first connecting hole 11 and a second connecting hole are provided on the side of the second U-shaped frame 8. The first U-shaped frame 7 is connected to the second U-shaped frame 8 by a first fastening bolt 9. The first fastening bolt 9 passes through the side of the first U-shaped frame 7 and the first connecting hole 11 and is fastened by a first fastening nut. The first fastening bolt 9 presses the connecting conductor 3 and the horizontal grounding body 2 to the bottom of the first U-shaped frame 7. The connecting conductor 3 and the graphite wire mesh sleeve 5 are connected through the second U-shaped frame 8. At this time, the first U-shaped frame 7 may not be applicable, and the connection between the connecting conductor 3 and the graphite wire mesh sleeve 5 can be achieved only through the second U-shaped frame 8. The second fastening bolt 10 passes through the second connection hole on the second U-shaped frame 8 and is fastened by the second fastening nut. The second U-shaped frame 8 presses the connecting conductor 3 to the bottom of the second U-shaped frame 8 through the second fastening bolt 10.

[0043] The present invention also provides a preparation method, which comprises the following steps:

[0044] S1. Prepare a hygroscopic mixture; the hygroscopic mixture is composed of the following raw materials in percentage by weight: 15-20% super absorbent resin, 25-30% modified bentonite, 30-35% expandable graphite, 10-15% polylight balls and 5-10% chopped glass fibers. Sodium polyacrylate super absorbent resin is selected, which has high water absorption rate and good water retention performance. The ratio of 15-20% can ensure that the grounding module has good water absorption and moisture retention ability, and will not affect other properties due to excessive content. For example, if the content is lower than 15%, the water absorption and moisture retention effect of the grounding module may not be obvious in arid environments; if it is higher than 20%, the viscosity of the mixture may be too large, affecting the subsequent mixing and molding process.

[0045] The use of highly absorbent resin, modified bentonite and highly conductive expanded graphite with microporous structure increases the water absorption and moisture retention performance of the grounding module, and significantly improves the grounding resistance stability of the grounding module in arid environments. The use of polylight balls greatly reduces the density and overall weight of the grounding module, solving the problem of heavy weight and inconvenient installation of traditional grounding modules. The exterior is wrapped with a lightweight conductive flexible graphite wire braid layer, which not only reduces the contact resistance between the grounding module and the soil, but also reduces the risk of module breakage. With this structural design, even if the module is broken, it will not have much impact on its handling and construction and grounding resistance reduction effect.

[0046] The specific steps of making the hygroscopic mixture are:

[0047] S1-1, treating the resin to obtain a highly absorbent resin;

[0048] S1-2, modifying bentonite to obtain modified bentonite;

[0049] S1-3, mixing highly water-absorbent resin, modified bentonite, expandable graphite, polylight balls and chopped glass fibers to obtain the hygroscopic mixture.

[0050] The specific steps of treating the resin to obtain the highly water-absorbent resin are:

[0051] S1-1-1. Dissolve polyvinyl pyrrolidone in deionized water to obtain a polyvinyl pyrrolidone mixed solution. Add an appropriate amount of deionized water to a clean beaker, add polyvinyl pyrrolidone in a mass ratio of 1:10, and stir until completely dissolved to obtain a polyvinyl pyrrolidone mixed solution.

[0052] S1-1-2, take nano silver powder and disperse it in a polyvinyl pyrrolidone mixed solution to obtain a nano silver powder dispersion; slowly add the weighed nano silver powder to the polyvinyl pyrrolidone mixed solution, and the amount of nano silver powder added is 5% to 10% of the mass of the super absorbent resin matrix material. Use an ultrasonic disperser to ultrasonically disperse for 30 to 60 minutes at a power of 200 to 300 W. During the ultrasonic dispersion process, the nano silver powder is uniformly dispersed in the solution under the action of the polyvinyl pyrrolidone mixed solution to form a stable nano silver powder dispersion. Ultrasonic dispersers are conventional existing technologies in the field and will not be described in detail here.

[0053] S1-1-3, dissolve sodium acrylate monomer in deionized water to obtain sodium acrylate solution, mix the sodium acrylate solution and nano silver powder dispersion and transfer to a reactor; add an appropriate amount of deionized water to the reactor, dissolve the sodium acrylate monomer in water, and prepare a sodium acrylate solution with a mass fraction of 20% to 30%. Then add the prepared nano silver powder dispersion, stir evenly, and make the nano silver powder evenly distributed in the sodium acrylate solution. The reactor is a conventional prior art in this field, and will not be described in detail here.

[0054] S1-1-4, add initiator and crosslinker to the reactor in sequence to obtain a reaction solution, wherein potassium persulfate is selected as the initiator and N,N'-methylenebisacrylamide is selected as the crosslinker. The amount of potassium persulfate is 0.5% to 1.0% of the mass of sodium acrylate monomer, and the amount of N,N'-methylenebisacrylamide is 0.1% to 0.3% of the mass of sodium acrylate monomer. Stir to completely dissolve the initiator and crosslinker and evenly disperse them in the reaction system; adjust the pH value of the reaction solution and then perform polymerization reaction to obtain a reaction product; use sodium hydroxide solution to adjust the pH value of the reaction system to 7 to 8. Seal the reactor, introduce nitrogen to remove oxygen in the system, then heat to 60 to 70°C, and react at this temperature for 3 to 5 hours. Under the action of the initiator, the sodium acrylate monomer undergoes polymerization reaction, and the crosslinker crosslinks the polymer molecular chains to form a highly absorbent resin with a three-dimensional network structure, and the nano silver powder is evenly wrapped in the resin network to give the resin conductive properties.

[0055] S1-1-5, the reaction product is washed, filtered, dried and crushed in sequence to obtain a highly absorbent resin. After the reaction is completed, the reaction product is taken out of the reactor and repeatedly washed with a large amount of deionized water to remove unreacted monomers, initiators, crosslinking agents and other impurities. During the washing process, a Buchner funnel is used for suction filtration to accelerate the filtration of the washing liquid. Repeat the washing-suction filtration operation 3 to 5 times until no impurities are detected in the washing liquid. The washed product is placed in a vacuum drying oven and dried for 12 to 24 hours at a temperature of 50 to 60°C and a vacuum degree of 0.08 to 0.09 MPa to completely remove the moisture in the product. The dried product is crushed using a pulverizer to obtain a highly absorbent resin powder with a certain particle size distribution and conductive properties. The particle size can be adjusted according to actual application requirements, generally controlled between 100 and 200 meshes. The Buchner funnel, vacuum drying oven and pulverizer are all conventional prior art in the field, and will not be described in detail here.

[0056] The specific steps of modifying the bentonite to obtain the modified bentonite are:

[0057] S1-2-1. Pre-treat bentonite; use organic modified bentonite to modify bentonite with organic cations to improve its dispersibility and adsorption, accounting for 25-30%. This ratio range can enhance the ion exchange capacity of the grounding module and help reduce the grounding resistance. When the content of modified bentonite is less than 25%, the ion exchange effect is weakened and the resistance reduction effect is not ideal; when it is higher than 30%, the strength of the grounding module may decrease.

[0058] The calcium-based bentonite raw soil is crushed and passed through a 100-mesh sieve to remove larger particle impurities. Take a certain amount of sieved bentonite, add an appropriate amount of deionized water, and prepare a bentonite suspension with a mass fraction of 10% to 15%. Under stirring conditions, adjust the pH value of the suspension to 7 to 8 with 0.1 mol / L hydrochloric acid or sodium hydroxide solution, stir for 30 to 40 minutes, and fully disperse the bentonite particles. Subsequently, the suspension is heated in a constant temperature water bath at 80 to 90 ° C for 1 to 2 hours for activation treatment to improve the reaction activity of the bentonite. After the reaction is completed, the suspension is cooled to room temperature, centrifuged at a speed of 3000 to 4000 r / min for 15 to 20 minutes with a centrifuge, the supernatant is discarded, the bottom precipitate is collected, and the precipitate is repeatedly washed with deionized water until neutral, and finally the precipitate is dried in an oven at 105 to 110 ° C to constant weight to obtain pretreated bentonite. The centrifuge is a conventional prior art in this field, and no more details are given here.

[0059] S1-2-2, dissolve hexadecyl trimethyl ammonium bromide in deionized water to obtain a hexadecyl trimethyl ammonium bromide solution, add the pretreated bentonite to the hexadecyl trimethyl ammonium bromide solution to react and obtain a mixed solution; calculate and accurately weigh a certain amount of hexadecyl trimethyl ammonium bromide according to the cation exchange capacity of the bentonite. Generally, the amount of hexadecyl trimethyl ammonium bromide is 1.0 to 1.5 times the cation exchange capacity of the bentonite. Dissolve the weighed hexadecyl trimethyl ammonium bromide in an appropriate amount of deionized water to prepare a hexadecyl trimethyl ammonium bromide solution with a concentration of 0.05 to 0.1 mol / L. Take the pretreated bentonite and add it to the hexadecyl trimethyl ammonium bromide solution, and control the solid-liquid ratio to 1:10 to 1:15 (g / mL). Heat the mixed solution to 60 to 80°C under stirring with an electric stirrer, and stir and react for 3 to 5 hours. During the stirring process, the organic cations in the hexadecyltrimethylammonium bromide molecules will undergo ion exchange reactions with the exchangeable cations between the bentonite crystal layers, insert into the interlayers of the bentonite, and achieve organic modification of the bentonite.

[0060] S1-2-3, centrifuge the mixed solution to obtain a precipitate; after the reaction is completed, cool the mixed solution to room temperature, and then centrifuge it at a speed of 4000-5000 r / min for 20-30 minutes in a centrifuge to collect the precipitate.

[0061] S1-2-4, wash, dry and grind the precipitate in sequence to obtain modified bentonite. Wash the precipitate repeatedly with anhydrous ethanol for 3 to 5 times to remove unreacted hexadecyltrimethylammonium bromide and other impurities adsorbed on the surface. The washed precipitate is dried in an oven at 60 to 70°C to constant weight to obtain a preliminary modified product. After grinding the preliminary modified product, pass it through a 200-mesh sieve to further improve the uniformity of the product. In order to enhance the stability of the modified bentonite, the sieved product can be calcined in a muffle furnace at 300 to 400°C for 1 to 2 hours to make the chemical bond between the organic cation and the bentonite more firmly bonded. The muffle furnace is a conventional prior art in the art and will not be described in detail here.

[0062] Select expandable graphite with a particle size between 100 and 200 meshes, which has rich microporous structure and high conductivity. The proportion is 30-35%, which can ensure that the grounding module has good conductivity and improve the grounding effect. If the content is less than 30%, the conductivity may be insufficient; if it is higher than 35%, the cost will increase and may affect the performance of other raw materials.

[0063] Polymer light balls with a particle size of 1 to 3 mm can effectively reduce the density and weight of the grounding module. The proportion is 10 to 15%. If the content of polymer light balls is less than 10%, the effect of reducing weight is not significant; if it is higher than 15%, it will affect the overall strength of the grounding module.

[0064] Chopped glass fibers with a length of 3 to 5 mm are used to enhance the overall strength and toughness of the hygroscopic mixture. The proportion is 5 to 10%. When the content of chopped glass fibers is less than 5%, the reinforcing effect is limited; when the content of chopped glass fibers is higher than 10%, it may affect the fluidity of the hygroscopic mixture and cause uneven mixing.

[0065] S2, pressing the hygroscopic mixture into a shape to obtain a hygroscopic block; adding the stirred hygroscopic mixture into a special mold, and pressing it into a shape using a hydraulic press.

[0066] Mixer selection: Use a double-shaft paddle mixer, which has high mixing efficiency and good mixing uniformity, and can ensure that all raw materials are fully mixed. First, stir at a low speed (100-150 rpm) for 5-8 minutes to make the various raw materials preliminarily mixed and uniform; then stir at a high speed (300-400 rpm) for 10-15 minutes to ensure that the hygroscopic mixture reaches a higher uniformity. If the stirring time is too short, the raw materials are not fully mixed, which affects the performance of the grounding module; if the stirring time is too long, the structure of some raw materials may be destroyed, which also affects the product quality.

[0067] The temperature during the mixing process is controlled at 20-35°C. Too high a temperature may cause the super absorbent resin to absorb water and swell prematurely, affecting the mixing effect; too low a temperature may deteriorate the fluidity of some raw materials and increase the difficulty of mixing.

[0068] A high-strength alloy steel mold is selected, which has good wear resistance and pressure resistance, can ensure that the mold does not deform during multiple pressing processes, and ensure the dimensional accuracy and appearance quality of the moisture-absorbing block. The hydraulic press, mixer and high-strength alloy steel mold are conventional existing technologies in this field, and will not be described in detail here.

[0069] According to the design specifications of the grounding module, the internal dimensions of the mold should be precisely controlled. For example, the common dimensions of the grounding module moisture absorbent block are 200-300mm long, 100-150mm wide, and 50-80mm high, and the mold size tolerance is controlled within ±0.5mm.

[0070] According to the characteristics of the hygroscopic mixture and the size of the hygroscopic block, the pressing pressure is set to 8-12MPa. If the pressure is too low, the hygroscopic block is difficult to compact and the strength is insufficient; if the pressure is too high, it may cause cracks in the hygroscopic block or damage the mold.

[0071] The pressing time is 10 to 15 minutes. During this period of time, the hygroscopic mixture can be fully formed under pressure to form a stable structure. If the pressing time is too short, the hygroscopic block will not be fully formed; if it is too long, the production efficiency will be reduced.

[0072] Holding time: After the pressing is completed, the holding time is set to 3 to 5 minutes. Holding the pressure can further consolidate the structure of the moisture-absorbing block under pressure and improve its stability and strength.

[0073] S3, weaving a graphite wire mesh sleeve outside the moisture absorbing block to obtain a grounding unit; using a rotary braiding machine to weave lightweight conductive flexible graphite wire outside the pressed moisture absorbing block. The rotary braiding machine is a conventional prior art in the field and will not be described in detail here.

[0074] Choose specially treated high-purity flexible graphite wire with a carbon content of more than 99% to ensure good conductivity. In terms of wire diameter, choose a wire diameter of 0.5 to 1.5 mm according to the specifications of the grounding module and actual application requirements. A thinner wire diameter, such as 0.5 mm, has a more delicate braided structure, which is suitable for scenes with high requirements on the appearance of the grounding module and relatively less stringent requirements on resistance reduction; a thicker wire diameter, such as 1.5 mm, can provide better conductivity and mechanical strength, and is suitable for situations with strict requirements on grounding resistance and harsh use environments.

[0075] The pressed moisture-absorbing block needs to be cleaned before weaving. Use a compressed air spray gun at a pressure of 0.4-0.6MPa to blow away the dust and debris on the surface to avoid affecting the weaving effect and the bonding force between the graphite wire and the moisture-absorbing block. At the same time, check whether there are cracks, bulges and other defects on the surface of the moisture-absorbing block. If there are any, repair or remove them to ensure the smooth weaving process and the close fit between the braided layer and the moisture-absorbing block.

[0076] The weaving speed is controlled at 20 to 40 rpm. A lower speed (about 20 rpm) is suitable for initial debugging and situations where weaving precision is extremely high, and can ensure that the graphite wires are arranged closely and evenly; a higher speed (about 40 rpm) can improve production efficiency, but it is necessary to ensure that the weaving process is stable, without skipping or breaking. In actual operation, the size of the hygroscopic block is adjusted. A larger hygroscopic block can appropriately increase the weaving speed to ensure the coverage rate of weaving per unit time.

[0077] Set the braiding angle to 45°~60°. This angle range enables the graphite wire to form a relatively stable cross structure on the surface of the hygroscopic block, enhancing the overall strength and stability of the braided layer. If the braiding angle is less than 45°, the graphite wire will not cover the axial direction of the hygroscopic block well, affecting the grounding performance; if it is greater than 60°, the tightness of the braided layer in the circumferential direction will decrease, which may cause the gaps between the graphite wires to be too large, reducing the protection effect on the hygroscopic block.

[0078] Tension control: The tension of the lightweight conductive flexible graphite wire is controlled at 5-10N by rotating the tension adjustment device of the braiding machine. Appropriate tension can ensure that the graphite wire is always kept tight during the braiding process, so that the braided layer fits tightly to the surface of the hygroscopic block, while avoiding the graphite wire breakage due to excessive tension or relaxation and wire jump due to insufficient tension. During the braiding process, the tension changes of the graphite wire are monitored in real time, and fine-tuning is performed in time if there is any fluctuation.

[0079] Every 5 to 10 minutes, check the appearance of the hygroscopic block being woven to see if the graphite wire is evenly distributed and whether there is any local sparseness or density. If unevenness is found, stop the machine immediately to adjust the parameters of the weaving machine or check the graphite wire supply system to ensure the quality of the woven layer.

[0080] During the weaving process, when the graphite wire needs to be connected, special graphite wire welding equipment is used for welding. The welding temperature is controlled at 800-1000℃ and the welding time is 3-5 seconds to ensure that the conductivity and mechanical strength of the connection point are similar to those of the original graphite wire. After welding, the connection point is polished to make its surface smooth to avoid affecting the appearance of the braided layer and the contact effect with the soil.

[0081] By installing a thickness monitoring sensor on the rotary braiding machine, the thickness of the braided layer is monitored in real time. The thickness of the braided layer is controlled between 2 and 5 mm and adjusted according to the use environment and performance requirements of the grounding module. In a highly corrosive soil environment, the braided layer thickness can be appropriately increased to 4 to 5 mm to improve the corrosion resistance of the grounding module; in a general environment, a braided layer thickness of 2 to 3 mm can meet the requirements.

[0082] After weaving is completed, an environmentally friendly adhesive is used to fix the braided layer. The adhesive is a graphite-based adhesive with good conductivity and weather resistance, which is evenly sprayed on the surface of the braided layer at a spraying amount of 50-100g / m 2 After spraying, cure at room temperature for 2 to 4 hours to allow the adhesive to fully penetrate between the graphite wires and enhance the integrity and stability of the braided layer.

[0083] Perform a comprehensive appearance inspection on the braided grounding module to check whether the braided layer has any defects such as damage or broken wires. If defects are found, use graphite wire of the same specification to manually repair them to ensure the integrity of the braided layer and avoid affecting the performance and service life of the grounding module.

[0084] S4. Connect multiple grounding units in series through connecting conductors to obtain a grounding module. When the rotary braiding machine is braiding, the flexible lightweight conductive flexible graphite wire is in a tightened state, and the part without the support of the hygroscopic block shrinks to a strip-like structure with a smaller cross-section. The junction is tied and fixed with a lightweight conductive flexible graphite wire (or corrosion-resistant metal wire or the above-mentioned clamp). According to the resistance reduction requirements, each group of grounding modules can have one or more hygroscopic blocks.

[0085] If lightweight conductive flexible graphite wire is used for binding, it should be consistent with the specifications of the braided graphite wire to ensure overall conductivity and corrosion resistance. Before use, cut the graphite wire into 30-50cm lengths for standby use. This length can meet the binding operation requirements and will not cause entanglement due to excessive length. If corrosion-resistant metal wire is used, stainless steel wire is preferred, and the wire diameter is controlled at 0.8-1.2mm. A thinner wire diameter is easy to operate and can be flexibly wrapped around the junction; a thicker wire diameter provides stronger binding strength. Before use, clean and rust-proof the stainless steel wire, polish the surface with sandpaper until it is bright, and then apply a thin layer of conductive grease on its surface to enhance conductivity and prevent rust.

[0086] The graphite wire mesh is tied at the junction of the hygroscopic block and the band-like structure formed by the shrinkage due to the lack of hygroscopic block support. Taking the binding of graphite wire or metal wire as an example, fix one end of the material near the marking point, and then tightly wrap the junction for 3 to 5 turns. Keep a certain tension during the winding process to make the binding firm. Finally, cut off the excess part.

[0087] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A highly water-absorbent and moisture-retaining flexible lightweight grounding module, characterized in that: The invention comprises a plurality of connecting conductors (3) and a plurality of grounding units distributed along a straight line. The connecting conductors (3) are used to connect adjacent grounding units or to connect a horizontal grounding body (2) buried in a grounding trench (1) and the grounding unit. The grounding unit comprises a graphite wire mesh sleeve (5). The graphite wire mesh sleeve (5) is wrapped with a moisture absorbing block (6). The connecting conductors (3) and the graphite wire mesh sleeve (5) as well as the connecting conductors (3) and the horizontal grounding body (2) are connected via a clamp (4).

2. The highly water-absorbent and moisture-retaining flexible lightweight grounding module according to claim 1, characterized in that: The graphite wire mesh sleeve (5) comprises a wrapping portion and a reduced diameter portion, wherein the wrapping portion is used to wrap the moisture absorbing block (6), and the reduced diameter portion is used to connect to the connecting conductor (3), and the mesh openings of the wrapping portion are larger than the mesh openings of the reduced diameter portion.

3. The method for preparing the grounding module according to claim 1 or 2, characterized in that: The preparation method comprises the following steps: S1, making a hygroscopic mixture; S2, pressing the hygroscopic mixture into a hygroscopic block; S3, weaving a graphite wire mesh sleeve outside the moisture absorbing block to obtain a grounding unit; S4. Connect multiple grounding units in series through connecting conductors to obtain a grounding module.

4. The preparation method according to claim 3, characterized in that: The moisture-absorbing mixture is composed of the following raw materials in percentage by weight: 15-20% of highly water-absorbent resin, 25-30% of modified bentonite, 30-35% of expandable graphite, 10-15% of polylight balls and 5-10% of short-cut glass fibers.

5. The preparation method according to claim 4, characterized in that: The specific steps of making the hygroscopic mixture are: S1-1, treating the resin to obtain a highly absorbent resin; S1-2, modifying bentonite to obtain modified bentonite; S1-3, mixing highly water-absorbent resin, modified bentonite, expandable graphite, polylight balls and chopped glass fibers to obtain the hygroscopic mixture.

6. The preparation method according to claim 5, characterized in that: The specific steps of treating the resin to obtain the highly water-absorbent resin are: S1-1-1, dissolving polyvinyl pyrrolidone in deionized water to obtain a polyvinyl pyrrolidone mixed solution; S1-1-2, dispersing nano silver powder in a polyvinyl pyrrolidone mixed solution to obtain a nano silver powder dispersion; S1-1-3, dissolving sodium acrylate monomer in deionized water to obtain a sodium acrylate solution, mixing the sodium acrylate solution and the nano silver powder dispersion and transferring the mixture to a reaction kettle; S1-1-4, adding an initiator and a cross-linking agent to a reaction kettle in sequence to obtain a reaction solution, adjusting the pH value of the reaction solution, and then performing a polymerization reaction to obtain a reaction product; S1-1-5. The reaction product is washed, filtered, dried and crushed in sequence to obtain a highly absorbent resin.

7. The preparation method according to claim 5, characterized in that: The specific steps of modifying the bentonite to obtain the modified bentonite are: S1-2-1, pre-treating bentonite; S1-2-2, dissolving hexadecyltrimethylammonium bromide in deionized water to obtain a hexadecyltrimethylammonium bromide solution, and adding the pretreated bentonite to the hexadecyltrimethylammonium bromide solution to react to obtain a mixed solution; S1-2-3, centrifuging the mixed solution to obtain a precipitate; S1-2-4. Wash, dry and grind the precipitate in sequence to obtain modified bentonite.

8. The preparation method according to claim 3, characterized in that: During the process of pressing the hygroscopic mixed material to obtain the hygroscopic block, the temperature is 20-35° C., the pressing pressure is 8-12 MPa, the pressing time is 10-15 min, and the holding time is 3-5 min.

9. The preparation method according to claim 3, characterized in that: In the process of weaving the graphite wire mesh sleeve outside the moisture absorbing block, the weaving speed is 20-40r / min, the weaving angle is 45-60°, the weaving tension is 5-10N, the weaving thickness is 2-5mm, and the wire diameter of the graphite wire mesh sleeve is 0.5-1.5mm.

10. The preparation method according to claim 3, characterized in that: The surface of the graphite wire mesh sleeve is sprayed with a graphite-based adhesive in an amount of 50 to 100 g / m 2 .

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