A wash-free composite material oil tank and a preparation method thereof

Abstract

The application discloses a wash-free composite material oil tank and a preparation method thereof, and belongs to the technical field of engine oil tanks. The preparation method comprises the following steps: applying liquid dust-removing adhesive on the inner walls of the upper cover and the lower cover of the oil tank to obtain a to-be-cured adhesive layer; applying sealing adhesive on the sealing surfaces of the upper cover and the lower cover of the oil tank, and splicing the upper cover and the lower cover of the oil tank; and curing the oil tank with the spliced upper cover and lower cover, so that the to-be-cured adhesive layer and the sealing adhesive are cured to obtain the composite material oil tank. The adhesive layer on the inner wall of the oil tank has the following effects: the particles such as polishing dust attached to the inner wall are directly captured and fixed by the adhesive; after the upper cover and the lower cover of the oil tank are closed, the floating particles in the sealed inner cavity of the oil tank are also captured and fixed by the adhesive during the sedimentation process. After the adhesive is completely cured, all potential contaminants are firmly bound to the surface of the inner wall of the oil tank to form a stable solid package, so that the movable free particles in the oil tank are fundamentally eliminated.

Description

Technical Field

[0001] This invention relates to the field of engine oil tank technology, and in particular to a self-cleaning composite material oil tank and its preparation method. Background Technology

[0002] Composite material fuel tanks are widely used due to their lightweight and corrosion resistance. However, during the molding process, due to material cutting, layup, curing, grinding, and trimming, movable dust, fiber debris, and particulate matter inevitably remain on the inner wall of the fuel tank. These free contaminants flow with the fuel during use, seriously threatening the safety and reliability of the fuel system (fuel pump, filter, pipeline, precision valves). Therefore, industry standards typically require that the inside of the fuel tank achieve an extremely high level of fuel cleanliness.

[0003] Traditional processes require a complex fuel cleaning process to clean the inside of the fuel tank after the tank is sealed. These processes are costly, inefficient, leave cleaning agent residues, and are difficult to completely remove contaminants from hard-to-reach areas. Summary of the Invention

[0004] This invention provides a cleaning-free composite material fuel tank and its preparation method, which can provide a cleaning-free composite material fuel tank.

[0005] In a first aspect, embodiments of the present invention provide a method for preparing a self-cleaning composite material fuel tank, comprising: S1, a liquid dust-removing adhesive is applied to the inner walls of both the upper and lower covers of the fuel tank to obtain a curing adhesive layer; wherein, the curing adhesive layer is used to capture dust on the inner wall during application and to capture dust in the internal space of the fuel tank after sealing and before curing. S2, apply sealant to the sealing surfaces of the upper and lower covers of the fuel tank, and then join the upper and lower covers of the fuel tank together; S3. The oil tank with the upper and lower covers assembled is cured, so that the adhesive layer to be cured and the sealant are cured, and a composite material oil tank is obtained.

[0006] Optionally, in S1, the dust removal structural adhesive includes epoxy resin, polyurethane, silicone, or acrylate adhesives.

[0007] Optionally, the viscosity of the dust removal adhesive in its uncured state at room temperature is 20,000 to 50,000 cP.

[0008] Optionally, the surface roughness Ra of the cured dust-removing adhesive is ≤3.2.

[0009] Optionally, in S1, the thickness of the cured adhesive layer is 10~300μm; or, In S1, the thickness of the cured adhesive layer is 30~100μm.

[0010] Optionally, in S1, a conductive filler is added to the adhesive layer to be cured to prevent static electricity buildup in the fuel tank during shaking. The conductive filler includes carbon nanotubes.

[0011] Optionally, in S1, the dust removal adhesive includes an adhesive with thixotropic properties.

[0012] Optionally, before S1, the following also includes: Grind and repair the sealing surfaces of the upper and lower covers of the fuel tank; Polish the uneven areas and burrs on the inner walls of the upper and lower covers of the fuel tank to smooth them out. Wipe the sealing surfaces of the upper and lower covers of the fuel tank with a clean, dry cotton cloth dampened with acetone to remove contaminants, including release agent and grease. After wiping the sealing surfaces clean, let them stand for 5 to 10 minutes. The sealing surfaces of the upper and lower covers of the fuel tank are initially sanded with 80-120 grit coarse sandpaper to increase roughness, and then finely sanded with 180-240 grit sandpaper to make the roughness uniform; the sanding depth is less than 0.1 mm. Use compressed air to blow away the wood chips and dust, then wipe again with a clean, dry cotton cloth soaked in acetone, and leave for 10 to 15 minutes.

[0013] Optionally, in S3, the curing process includes natural curing or accelerated curing methods: All external pipe joints of the fuel tank are sealed to prevent external dust particles from entering the fuel tank; Natural curing: The oil tank is laid flat in an environment of 5~10℃ and left to stand for 24 hours to extend the curing time of the adhesive and ensure that the adhesive completely adsorbs and fixes the particles floating in the oil tank cavity before curing. Then the oil tank is placed at room temperature for 48 hours to cure, so that the adhesive is completely cured. or, All external pipe joints of the fuel tank are sealed to prevent external dust particles from entering the fuel tank; Accelerated curing: Place the oil tank in a heating device with independent heat sources at the top and bottom, so that the bottom of the oil tank is close to the heat source at a temperature of 50~60℃ and the top of the oil tank is close to the heat source at a temperature of 20~30℃. After heating the bottom heat source for 2~3 hours, turn off the heat source. After heating the top heat source for 2~3 hours, turn off the heat source. Then place the oil tank at room temperature for 48 hours to cure, allowing the adhesive to fully cure.

[0014] Secondly, embodiments of the present invention also provide a cleaning-free composite material fuel tank, which is prepared according to any of the preparation methods in the above embodiments.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: (a) Fundamental change: from "post-cleaning" to "process control", from passively removing pollutants to actively fixing pollutants, subverting the traditional fuel tank cleaning process.

[0016] (ii) 100% elimination of cleaning process: saves fuel tank cleaning equipment and labor costs, and greatly improves fuel tank production efficiency.

[0017] (iii) Reliable cleanliness: The possibility of particle movement is physically eliminated, and the cleanliness level is high and stable.

[0018] (iv) No secondary pollution: avoids the risk of residual cleaning media.

[0019] (v) Applicable to complex structures: For composite material oil tanks with irregular cavities, it can solve the problem of cleaning dead corners of oil tank equipment.

[0020] (vi) Simple process: Only one glue application step is needed, which is easy to integrate into the production line. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic cross-sectional view of a composite material fuel tank provided by the present invention.

[0023] In the picture: 1-Top cover; 2-Sealing surface; 3-Dust removal adhesive; 4-Lower cover. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0025] Please refer to Figure 1 This invention provides a method for preparing a self-cleaning composite material fuel tank, comprising: S1, liquid dust-removing adhesive 3 is applied to the inner wall of the upper cover 1 and the inner wall of the lower cover 4 of the fuel tank to obtain a curing adhesive layer; wherein, the curing adhesive layer is used to capture dust on the inner wall during application and to capture dust in the internal space of the fuel tank after sealing and before curing. S2, apply sealant to the sealing surfaces 2 of the upper cover 1 and lower cover 4 of the fuel tank, and then join the upper cover 1 and lower cover 4 of the fuel tank together; S3, the oil tank with the upper cover 1 and lower cover 4 spliced ​​together is cured, so that the adhesive layer to be cured and the sealant are cured, and a composite material oil tank is obtained.

[0026] In this embodiment, before the upper cover 1 and lower cover 4 of the fuel tank are closed and sealed, a layer of dust-removing adhesive 3 is applied to the inner wall of the fuel tank to obtain a curing adhesive layer. This process has two key functions: first, before the covers are closed, grinding dust and other particulate matter attached to the inner wall are directly captured and fixed by the adhesive; second, after the fuel tank is closed, floating particulate matter in the sealed inner cavity of the fuel tank will also be captured and fixed by the adhesive during the settling process. After the adhesive is fully cured, all potential contaminants are firmly bound to the surface of the inner wall of the fuel tank, forming a stable solid envelope, thereby fundamentally eliminating free-moving particulate matter inside the fuel tank. Based on this, the cleanliness of the fuel tank can directly meet the NAS cleanliness requirements of fuel systems in aerospace, automotive and other fields, achieving true "clean-free" operation.

[0027] In some embodiments of the present invention, in S1, the dust removal structural adhesive includes epoxy resin, polyurethane, silicone, or acrylate adhesives.

[0028] In this embodiment, the dust-removing adhesive 3 needs to have the following characteristics: 1) The adhesive may be selected from epoxy resin, polyurethane, silicone or acrylate adhesives, or equivalent alternatives thereof.

[0029] 2) The adhesive is initially liquid and has sufficient surface tackiness to effectively capture and wet particles.

[0030] 3) The coating method can be spraying, brushing, roller coating or flow coating.

[0031] 4) The adhesive properties of the uncured adhesive are used to fix the pollutants, so that the particulate pollutants attached to the inner wall of the composite material tank are adhered to in situ and embedded in the adhesive layer. After the upper cover 1 and the lower cover 4 of the tank are closed, the floating particulate matter in the inner cavity of the tank settles and solidifies on the adhesive on the inner wall of the tank, thus being fixed.

[0032] 5) The adhesive layer has a smooth surface after curing, with a roughness Ra≤3.2.

[0033] 6) The preferred viscosity of the adhesive at room temperature is 20,000~50,000 cP.

[0034] 7) After the adhesive layer is cured, it has the properties of being resistant to aviation kerosene, corrosion, and high and low temperature cycles.

[0035] 8) The thickness of the adhesive layer after curing is 10~200μm, preferably 30~100μm, which is sufficient to capture polluting particles without excessively increasing the weight of the composite material tank.

[0036] 9) Conductive fillers (such as carbon nanotubes) can be added to adhesives to prevent static buildup.

[0037] 10) The adhesive is preferably a thixotropic adhesive. When the adhesive is stationary on the inner wall surface of the oil tank, the viscosity of the adhesive increases, which prevents the adhesive from dripping.

[0038] In this embodiment, the dust removal adhesive 3 can be J133 adhesive.

[0039] In some embodiments of the present invention, prior to S1, the method further includes: Grind and repair the sealing surfaces 2 of the upper cover 1 and lower cover 4 of the fuel tank; Polish the uneven areas and burrs on the inner walls of the upper cover 1 and lower cover 4 of the fuel tank to smooth out any imperfections. Wipe the sealing surfaces 2 of the upper cover 1 and lower cover 4 of the oil tank with a clean, dry cotton cloth soaked in acetone to remove contaminants including release agent and grease. After wiping the sealing surfaces 2 clean, let them stand for 5 to 10 minutes. The sealing surfaces 2 of the upper cover 1 and lower cover 4 of the oil tank are initially polished with 80-120 grit coarse sandpaper to increase roughness, and then finely polished with 180-240 grit sandpaper to make the roughness uniform; wherein the polishing depth is less than 0.1 mm. Use compressed air to blow away the wood chips and dust, then wipe again with a clean, dry cotton cloth soaked in acetone, and leave for 10 to 15 minutes.

[0040] Specifically, the entire construction process is as follows: 1) Manufacture the upper cover 1 and lower cover 4 of the composite material oil tank respectively, and complete the grinding and finishing process of the bonding area of ​​the upper cover 1 and lower cover 4 of the oil tank.

[0041] 2) Grind the inner walls of the upper cover 1 and lower cover 4 of the oil tank to smooth out any unevenness and burrs.

[0042] 3) Before sanding the sealing surface 2 of the composite material product, use a clean and dry cotton cloth soaked in acetone to carefully wipe the surface to be sanded to remove the release agent, grease and other contaminants. After wiping the sealing surface 2 clean, let it stand for 5 to 10 minutes.

[0043] 4) For the initial sanding of the sealing surface 2 of the bonding area between the upper cover 1 and the lower cover 4 of the oil tank, 80-120 grit coarse sandpaper can be used to initially increase the roughness. Subsequently, 180-240 grit sandpaper is used for fine sanding to make the roughness of the sealing surface 2 uniform, providing a good surface for sealing.

[0044] 5) Grinding requirements: The surface should be ground evenly, with no obvious omissions or unground areas. Grinding marks should be uniform and consistent, avoiding areas that are too deep or too shallow. The grinding depth should be less than 0.1mm. The pressure and speed should be controlled during grinding to avoid overheating and damaging the fibers of the composite material surface. After grinding, sealing surface 2 should have a diffuse reflective state. Touching sealing surface 2 should feel rough but without sharp protrusions or depressions.

[0045] 6) After grinding, use compressed air to blow away composite material debris and dust from the sealing surfaces 2 of the bonding area between the upper cover 1 and the lower cover 4 of the oil tank, as well as the ground areas of the inner walls of the upper cover 1 and the lower cover 4. Then, carefully wipe with a clean, dry cotton cloth soaked in acetone until there are no visible stains on the cloth, and let it sit for 10 to 15 minutes. During this time, ensure the surrounding environment is clean to avoid secondary contamination of the sealing surfaces 2.

[0046] 7) Use a clean brush to apply a thin layer of J133 adhesive to the inner walls of the upper cover 1 and lower cover 4 of the fuel tank. Ensure that the adhesive completely covers the inner walls of the upper cover 1 and lower cover 4 of the fuel tank. For areas with complex inner wall structures that are difficult to reach with a brush, J133 adhesive can be applied by spraying or flow coating. Finally, ensure that the entire surface of the complex inner wall structure of the fuel tank is covered with J133 adhesive.

[0047] 8) Apply sealant to the sealing surface 2 of the bonding area between the upper cover 1 and the lower cover 4 of the fuel tank. Apply an appropriate amount of sealant to avoid fuel tank leakage.

[0048] 9) Assemble and seal the upper cover 1 and lower cover 4 of the oil tank, which are coated with sealant, so that the sealant is evenly squeezed out in the joint between the upper cover 1 and the lower cover 4.

[0049] 10) Depending on the type of adhesive and sealant, it can be cured at room temperature or in an oven.

[0050] 11) Once the fuel tank adhesive has cured, a clean fuel tank with satisfactory internal wall cleanliness is obtained, eliminating the need for internal rinsing and cleaning.

[0051] In some embodiments of the present invention, in S3, the curing process includes natural curing or accelerated curing methods: All external pipe joints of the fuel tank are sealed to prevent external dust particles from entering the fuel tank; Natural curing: The oil tank is laid flat in an environment of 5~10℃ and left to stand for 24 hours to extend the curing time of the adhesive and ensure that the adhesive completely adsorbs and fixes the particles floating in the oil tank cavity before curing. Then the oil tank is placed at room temperature for 48 hours to cure, so that the adhesive is completely cured. or, All external pipe joints of the fuel tank are sealed to prevent external dust particles from entering the fuel tank; Accelerated curing: The oil tank is placed in a heating device with independent heat sources at the top and bottom. The bottom of the oil tank is placed near a heat source with a temperature of 50~60℃, and the top of the oil tank is placed near a heat source with a temperature of 20~30℃. The heat source at the bottom is turned off after heating for 2~3 hours, and the heat source at the top is turned off after heating for 2~3 hours. This process uses the temperature difference effect to accelerate the directional flow of floating particles in the oil tank cavity, so as to achieve the purpose of the adhesive quickly capturing and fixing the particles. Then place the oil tank at room temperature for 48 hours to cure, allowing the adhesive to fully cure.

[0052] In this embodiment, after the fuel tank is closed, all external pipe joints are sealed to prevent external dust particles from entering the fuel tank. To ensure that 100% of the dust particles floating in the fuel tank cavity are captured and fixed by the adhesive, the fuel tank should be placed flat in an environment of 5℃~10℃ for 24 hours to extend the curing time of the adhesive and ensure that the dust particles completely settle. Then, the fuel tank should be placed at room temperature for 48 hours to cure.

[0053] It should be noted that in order to prevent the sealed oil tank from deforming at high temperatures, the curing temperature should not be too high. The preferred curing temperature is room temperature (25±5)℃, and the curing time is 24h~48h. If rapid curing is required, the curing temperature can be appropriately increased. For example, it can be (65±5)℃×3h~4h or 80℃×1h~2h.

[0054] Furthermore, to balance the cleanliness of the oil tank interior with curing efficiency, a differential heating method can be used, placing the oil tank in a heating device with a high temperature at the bottom and a normal temperature at the top. The temperature difference between the top and bottom causes the gas at the bottom of the oil tank to expand and move upwards. After moving to the top, it cools and collapses, then moves to both sides of the oil tank and descends along the inner walls to the bottom. The gas at the bottom is heated and rises again from the middle, thus forming a continuously circulating airflow. Micro-dust flows along the inner wall with the air and adheres to the adhesive layer, ultimately achieving the effect of accelerating micro-dust capture and accelerating curing.

[0055] It should also be noted that because the temperature difference between the upper and lower sides is small, the airflow speed is not fast, which prevents the temperature inside the fuel tank from rising rapidly to a uniform level, thus losing the thermal dynamics of the temperature difference and making it difficult to continuously achieve air circulation. In addition, the small temperature difference and the overall low temperature can also prevent the sealed fuel tank from expanding and generating thermal stress.

[0056] This invention also provides a self-cleaning composite material fuel tank, prepared according to any of the preparation methods described in the above embodiments.

[0057] To more clearly illustrate the technical solution and advantages of the present invention, the following describes the solution of this application in detail through several embodiments.

[0058] Example 1 The two-component epoxy J133 adhesive is used as a dust removal adhesive for the inner wall of the fuel tank. The main properties of the adhesive are shown in the table below: The application process is as follows: (1) Construction environment: The construction temperature is 25±5℃ and the relative humidity is ≤65%.

[0059] (2) Preparation of adhesive solution: Weigh components A and B accurately according to the ratio of A:B = 100:20 (mass ratio), and stir thoroughly. The adhesive solution should be prepared immediately before use, and the shelf life of the prepared adhesive solution is ≤40 minutes.

[0060] (3) Applying adhesive: Apply the prepared adhesive solution evenly to the inner wall surface of the tank, with a thickness of 30~100μm. (4) Curing: Curing at room temperature (25±5)℃ for 24h~48h.

[0061] The obtained oil tank was tested using the particle counting method, and the cleanliness level was determined to be NAS8.

[0062] Finally, it should be noted that the above embodiments and comparative examples are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments and comparative examples, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments and comparative examples, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments and comparative examples of the present invention.

Claims

1. A method for preparing a self-cleaning composite material fuel tank, characterized in that, include: S1, apply liquid dust-removing adhesive (3) to both the inner wall of the upper cover (1) and the inner wall of the lower cover (4) of the fuel tank to obtain a curing adhesive layer; wherein, the curing adhesive layer is used to capture dust on the inner wall during application and to capture dust in the internal space of the fuel tank after sealing and before curing. S2, apply sealant to the sealing surfaces (2) of the upper cover (1) and lower cover (4) of the fuel tank, and splice the upper cover (1) and lower cover (4) of the fuel tank; S3, the oil tank with the upper cover (1) and lower cover (4) spliced ​​together is cured, so that the adhesive layer to be cured and the sealant are cured, and a composite material oil tank is obtained.

2. The method for preparing a self-cleaning composite material fuel tank according to claim 1, characterized in that, In S1, the dust removal structural adhesive includes epoxy resin, polyurethane, silicone, or acrylate adhesives.

3. The method for preparing a self-cleaning composite material fuel tank according to claim 1, characterized in that, The viscosity of the dust removal adhesive (3) in the uncured state at room temperature is 20,000~50,000 cP.

4. The method for preparing a self-cleaning composite material fuel tank according to claim 1, characterized in that, The surface roughness Ra of the dust removal adhesive (3) after curing is ≤3.

2.

5. The method for preparing a self-cleaning composite material fuel tank according to claim 1, characterized in that, In S1, the thickness of the cured adhesive layer is 10~300μm; or, In S1, the thickness of the cured adhesive layer is 30~100μm.

6. The method for preparing a self-cleaning composite material fuel tank according to claim 1, characterized in that, In S1, conductive fillers are added to the adhesive layer to be cured to prevent static electricity buildup in the fuel tank during shaking. The conductive fillers include carbon nanotubes.

7. The method for preparing a self-cleaning composite material fuel tank according to claim 1, characterized in that, In S1, the dust removal adhesive (3) includes an adhesive with thixotropic properties.

8. The method for preparing a self-cleaning composite material fuel tank according to claim 1, characterized in that, Before S1, it also includes: Grind and repair the sealing surfaces (2) of the upper cover (1) and lower cover (4) of the fuel tank; Grind the uneven areas and burrs on the inner walls of the upper cover (1) and lower cover (4) of the oil tank to smooth them out. Wipe the sealing surfaces (2) of the upper cover (1) and lower cover (4) of the oil tank with a clean, dry cotton cloth soaked in acetone to remove contaminants including release agent and grease. After wiping the sealing surfaces (2) clean, let them stand for 5 to 10 minutes. The sealing surfaces (2) of the upper cover (1) and lower cover (4) of the oil tank are initially polished with 80-120 grit coarse sandpaper to increase roughness, and then finely polished with 180-240 grit sandpaper to make the roughness uniform; wherein the polishing depth is less than 0.1 mm; Use compressed air to blow away the wood chips and dust, then wipe again with a clean, dry cotton cloth soaked in acetone, and leave for 10 to 15 minutes.

9. The method for preparing a self-cleaning composite material fuel tank according to claim 1, characterized in that, In S3, the curing process includes natural curing or accelerated curing methods: All external pipe joints of the fuel tank are sealed to prevent external dust particles from entering the fuel tank; Natural curing: The oil tank is laid flat in an environment of 5~10℃ and left to stand for 24 hours to extend the curing time of the adhesive and ensure that the adhesive completely adsorbs and fixes the particles floating in the oil tank cavity before curing. Then the oil tank is placed at room temperature for 48 hours to cure, so that the adhesive is completely cured. or, All external pipe joints of the fuel tank are sealed to prevent external dust particles from entering the fuel tank; Accelerated curing: Place the oil tank in a heating device with independent heat sources at the top and bottom, so that the bottom of the oil tank is close to the heat source at a temperature of 50~60℃ and the top of the oil tank is close to the heat source at a temperature of 20~30℃. After heating the bottom heat source for 2~3 hours, turn off the heat source. After heating the top heat source for 2~3 hours, turn off the heat source. Then place the oil tank at room temperature for 48 hours to cure, allowing the adhesive to fully cure.

10. A self-cleaning composite material fuel tank, characterized in that, It is prepared by the preparation method according to any one of claims 1-9.

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