Composite material oil tank and manufacturing method thereof

Abstract

The invention belongs to the technical field of vehicle fuel tanks, and discloses a composite fuel tank and a manufacturing method thereof.The composite fuel tank comprises a tank body and an end cover, the tank body and the end cover are bonded to form a closed structure after being formed respectively, and the tank body and the end cover are formed through an autoclave forming technology. According to the manufacturing process, the end cover and the box body are combined, the box body and the end cover are formed respectively, and then the end cover and the box body are assembled in a bonding mode. And when the carbon fiber composite material is paved, a secondary paving process is adopted, so that the sealing performance of the product is improved, and the problem of insufficient sealing performance possibly caused by split paving is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of vehicle fuel tanks, and in particular relates to a composite fuel tank for special vehicles and a manufacturing method thereof. Background Art

[0002] Special vehicle fuel tanks are used to load and store fuel, providing sufficient fuel for the engine and the vehicle to meet normal driving needs. Fuel tanks are generally designed with thin-walled box structures, and the internal space is used to store fuel. The overall designer will reserve a certain amount of space for the fuel tank based on the layout of the vehicle. The fuel subsystem designer will design the fuel tank structure, material selection, and the location of the inlet and outlet ports based on the reserved space. Fuel tanks are generally made of steel (08AL) or aluminum alloy (5A06, 5083). A special vehicle fuel tank is designed with 5-10 tanks, which accounts for a large weight of the vehicle. The design structure is usually a special-shaped structure, which brings great difficulties to stamping-welding and other processes.

[0003] Since the special vehicle fuel tank is made of metal material and is overweight, it is not conducive to the lightweight design and manufacturing of the whole vehicle, and cannot meet the design weight requirements, and cannot achieve functions such as remote vehicle deployment. Secondly, the manufacturing process adopts sheet metal stamping, bending and then welding, which has problems such as long manufacturing cycle, stamping cracking, welding deformation, easy leakage and poor appearance quality. During use, oil leakage often occurs, affecting the normal use and training of equipment. Summary of the invention

[0004] The technical problem to be solved by the present invention is that the fuel tank of a special vehicle has a complex structure, a large weight, and poor sealing performance in the manufacturing process.

[0005] In order to solve the above technical problems, the specific technical solutions of the present invention are as follows:

[0006] A composite material oil tank comprises a tank body and an end cover, wherein the tank body and the end cover are respectively formed and then bonded to form a closed structure.

[0007] Preferably, the box body and the end cover are formed by a hot-press forming process.

[0008] Preferably, the box body and the end cover are formed by a compression molding process.

[0009] Preferably, the box body and the end cover are formed by hand lay-up process.

[0010] The present invention also provides a method for manufacturing a composite material fuel tank, comprising the following steps:

[0011] Step 1. Preparation

[0012] Step 1.1, use 95% industrial alcohol to wipe the mold surface to remove oil stains and other debris on the mold surface; use the sealant to wipe the mold surface 6-8 times, and then wipe the release agent on the mold surface 6-8 times. After wiping once, leave it for 10-15 minutes before starting the next wipe. After wiping, there is no watermark on the mold surface and it remains even;

[0013] Step 1.2, take out the composite material raw materials stored below -10°C, and use a CNC cutting machine to cut the composite material cloth for paving according to the two-dimensional graphics, wherein the rounded corners and right angles should be cut and laid, and placed and folded;

[0014] Step 2: One-time paving work

[0015] Step 2.1, prepare a single layer of carbon fiber cloth, and lay it alternately on the mold according to the requirements of the drawing and the direction of the composite material. The directions of the composite material are 0° and 90° respectively. It can be laid in combination with 45° and other directions according to the actual needs of the product. The number of laying layers = 1 / 3 of the total thickness of the part ÷ single layer thickness;

[0016] Step 2.2: During the paving process, the direction of the scraper to flatten the composite material should be consistent with the direction of the fiber. In the paving process at corners and other locations with sudden changes in shape, the carbon fiber cloth should be cut and laid separately to prevent folding. Reinforced fiber cloth should be added at the cut locations. Strengthening locations such as the ridges of structural parts should ensure that the carbon fibers overlap to increase the strength of the local locations.

[0017] Step 3: Autoclave forming

[0018] Step 3.1, cover the laid composite material layer by layer with nylon demoulding cloth, breathable felt and high temperature resistant plastic, and then seal the plastic along the edge with rubber strips, tie the plastic cloth with rubber strips at the wide part to ensure that the plastic above the composite material is flat, install a vacuum valve at the diagonal of the composite material flat plate, connect the air pipe for vacuuming to test vacuum the composite material laying layer;

[0019] Step 3.2, check the sealing of plastic bonding. If the sealing is OK, push the composite parts into the autoclave via a trailer and close the autoclave door;

[0020] Step 3.3, hot pressing: first heat the autoclave to 60°C, keep it warm for 30 minutes, then heat it to 95°C, keep it warm for 30 minutes, pressurize it to 0.6MPa after the heat preservation, heat it to 120°C simultaneously, keep it warm and pressurize it for 90 minutes, finally cool it down to 60°C and reduce the pressure to 0MPa, and the heating and cooling rates are both 5°C / min;

[0021] Step 3.4, taking out the structure formed in the autoclave and demoulding;

[0022] Step 4: Bonding of structural parts

[0023] Bond the box body and cover body structure parts obtained in step 3 with structural adhesive to form a closed box body;

[0024] Step 5: Secondary paving work

[0025] Step 5.1, prepare a single layer of carbon fiber cloth, and alternately lay it on the closed box obtained in step 4 according to the requirements of the drawing and the direction of the composite material. The directions of the composite material are 0° and 90° respectively. It can be laid in combination with 45° and other directions according to the actual needs of the product. The number of laying layers = 2 / 3 of the total thickness of the part ÷ the thickness of the single layer;

[0026] Step 5.2: During the paving process, the direction in which the scraper flattens the composite material should be consistent with the direction of the fibers. To prevent the carbon fiber cloth from folding at corners and other locations with sudden changes in shape, it is necessary to cut them apart and pave them separately. Reinforcing fiber cloth is required at the cut locations, and the edges of structural parts and other reinforced locations should ensure that the carbon fibers overlap to increase the strength of the local locations.

[0027] Among them, the total thickness of the box body is 3mm, and the total thickness of the cover body is 3mm.

[0028] Among them, the structural adhesive is a high temperature resistant epoxy structural adhesive.

[0029] The present invention has the following advantages: the fuel tank is manufactured using lightweight, high-strength carbon fiber and other composite materials, which have unique advantages such as light weight, high strength, and corrosion resistance, and can achieve lightweight fuel tanks. Secondly, the manufacturing process uses the end cover and the box body to form the box body and the end cover separately, and then the end cover and the box body are bonded and assembled. This technical solution reduces the weight of the product while eliminating problems such as leakage caused by the stamping-welding process. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the fuel tank structure;

[0031] Figure 2 It is a schematic diagram of the box;

[0032] Figure 3 Schematic diagram of the end cover. DETAILED DESCRIPTION

[0033] In order to better understand the purpose, structure and function of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings.

[0034] like Figure 1-Figure 3 As shown, according to the thin-wall sealing structure characteristics of the oil tank and the characteristics of the composite material manufacturing process, this embodiment divides the oil tank into two parts, the tank body and the end cover, and the two parts are formed separately and then bonded. The two parts are formed by the autoclave forming process. Finally, the oil inlet and outlet, the sensor attachment, the handle and other attachments are assembled.

[0035] The composite material forming process referred to in this embodiment includes but is not limited to autoclave forming, compression molding, hand lay-up forming, etc. Due to the complex structure of the fuel tank, the autoclave forming process has the advantages of uniform forming and all-round force. The present invention uses autoclave forming. If other composite material forming processes are used, they are also within the protection scope of the present invention. The fuel tank structure shown in the present invention is disassembled into two parts. In the actual development and production process, the fuel tank can be disassembled into two or more parts according to the complexity of the fuel tank and the difficulty of demolding the parts. The technical solution is the same and is also within the protection scope of the present invention. The specific manufacturing method is as follows:

[0036] Step 1. Preparation

[0037] (1) Use 95% industrial alcohol to wipe the mold surface to remove oil stains and other debris on the mold surface;

[0038] Use the sealant to wipe the mold surface 6-8 times, and then wipe the release agent on the mold surface 6-8 times. After wiping once, leave it for 10-15 minutes before starting the next wipe. After wiping, there is no watermark on the mold surface and it remains even.

[0039] (2) Take out the composite material raw materials stored below -10°C, and use a CNC cutting machine to cut the composite material cloth for paving according to the two-dimensional graphics. The rounded corners and right angles should be cut and paved, and then placed and folded.

[0040] Step 2: One-time paving work

[0041] (1) Prepare a single layer of carbon fiber cloth and alternately lay it on the mold according to the requirements of the drawing and the direction of the composite material. The directions of the composite material are 0° and 90° respectively. Combined laying with 45° and other directions can be carried out according to the actual needs of the product. The number of laying layers = 1 / 3 of the total thickness ÷ single layer thickness (generally the total thickness of the box body is 3 mm, and the total thickness of the cover body is 3 mm);

[0042] (2) During the paving process, the direction in which the scraper scrapes the composite material is consistent with the direction of the fiber. During the paving process at corners and other locations with sudden changes in shape, the carbon fiber cloth should be prevented from folding. It needs to be cut and laid separately. Reinforced fiber cloth should be added at the cut locations. The carbon fiber overlap should be ensured as much as possible at the reinforcement locations such as the ridges of the structural parts to increase the strength of the local locations.

[0043] Step 3: Autoclave forming

[0044] (1) Vacuuming: Cover the laid composite material layer by layer with nylon release cloth, breathable felt, and high-temperature resistant plastic, and then seal the plastic along the edge with rubber strips. Tie the plastic cloth with rubber strips at the wide part to ensure that the plastic above the composite material is flattened. Install a vacuum valve at the diagonal part of the composite material flat plate, connect the air pipe for vacuuming, and test vacuuming the composite material laying layer;

[0045] (2) Check the sealing of plastic bonding. If the sealing is OK, push the composite parts into the autoclave via a trailer and close the autoclave door.

[0046] (3) Hot pressing: first heat the autoclave to 60°C, keep it warm for 30 min, then heat it to 95°C, keep it warm for 30 min, pressurize it to 0.6 MPa after the heat preservation, then heat it to 120°C, keep it warm and pressurize it for 90 min, and finally cool it down to 60°C and reduce the pressure to 0 MPa, with the heating and cooling rates both being 5°C / min;

[0047] (4) Take out the structural parts formed by the autoclave and demould them.

[0048] Step 4: Bonding of structural parts

[0049] The box body and the cover body obtained in step 3 are bonded with structural adhesive (generally high temperature resistant epoxy structural adhesive) to form a closed box body.

[0050] Step 5: Secondary paving work

[0051] (1) Prepare a single layer of carbon fiber cloth, and alternately lay it on the closed box obtained in step 4 according to the requirements of the drawing and the direction of the composite material. The directions of the composite material are 0° and 90° respectively. Combined laying with directions of 45° and other directions can be performed according to the actual needs of the product. The number of laying layers = 2 / 3 of the total thickness ÷ single layer thickness (generally the total thickness of the box is 3 mm, and the total thickness of the cover is 3 mm);

[0052] (2) During the paving process, the scraper is required to scrape the composite material in the same direction as the fiber direction. To prevent the carbon fiber cloth from folding during the paving process at corners and other locations with sudden changes in shape, it is necessary to cut it apart and lay it separately. Reinforcing fiber cloth is required at the cut locations. The carbon fiber overlap is ensured as much as possible at the reinforcement locations such as the ribs of the structural parts to increase the strength of the local location.

[0053] The design of the present invention adopts lightweight, high-strength carbon fiber and other composite materials to manufacture the fuel tank, which has the unique advantages of light weight, high strength, corrosion resistance, etc., and can achieve lightweight fuel tank. Secondly, the manufacturing process adopts the combination of end cover and box body, and the box body and end cover are formed separately, and then the end cover and box body are bonded and assembled. When laying the carbon fiber composite material, a secondary laying process is adopted to improve the sealing of the product and avoid the problem of insufficient sealing that may be caused by split laying. This technical solution reduces the weight of the product while eliminating problems such as leakage caused by the stamping-welding process.

[0054] Although the embodiments of the present invention are described in conjunction with the accompanying drawings, it is apparent to those skilled in the art that several modifications and improvements may be made without departing from the principles of the present invention, and these modifications and improvements should also be considered to fall within the scope of protection of the present invention.

Claims

1. A composite fuel tank, characterized in that: The utility model comprises a box body and an end cover, wherein the box body and the end cover are respectively formed and then bonded to form a closed structure.

2. The composite fuel tank according to claim 1, characterized in that: The box body and end cover are formed by hot-pressing process.

3. The composite fuel tank according to claim 1, characterized in that: The box body and the end cover are formed by a compression molding process.

4. The composite fuel tank according to claim 1, characterized in that: The box body and end cover are formed by hand lay-up process.

5. A method for manufacturing a composite fuel tank, characterized in that: The steps include: Step 1. Preparation Step 1.1, use 95% industrial alcohol to wipe the mold surface to remove oil stains and other debris on the mold surface; use the sealant to wipe the mold surface 6-8 times, and then wipe the release agent on the mold surface 6-8 times. After wiping once, leave it for 10-15 minutes before starting the next wipe. After wiping, there is no watermark on the mold surface and it remains even; Step 1.2, take out the composite material raw materials stored below -10°C, and use a CNC cutting machine to cut the composite material cloth for paving according to the two-dimensional graphics, wherein the rounded corners and right angles should be cut and laid, and placed and folded; Step 2: One-time paving work Step 2.1, prepare a single layer of carbon fiber cloth, and lay it alternately on the mold according to the requirements of the drawing and the direction of the composite material. The directions of the composite material are 0° and 90° respectively. It can be laid in combination with 45° and other directions according to the actual needs of the product. The number of laying layers = 1 / 3 of the total thickness of the part ÷ single layer thickness; Step 2.2: During the paving process, the direction of the scraper to flatten the composite material should be consistent with the direction of the fiber. In the paving process at corners and other locations with sudden changes in shape, the carbon fiber cloth should be cut and laid separately to prevent folding. Reinforced fiber cloth should be added at the cut locations. Strengthening locations such as the ridges of structural parts should ensure that the carbon fibers overlap to increase the strength of the local locations. Step 3: Autoclave forming Step 3.1, cover the laid composite material layer by layer with nylon demoulding cloth, breathable felt and high temperature resistant plastic, and then seal the plastic along the edge with rubber strips, tie the plastic cloth with rubber strips at the wide part to ensure that the plastic above the composite material is flat, install a vacuum valve at the diagonal of the composite material flat plate, connect the air pipe for vacuuming to test vacuum the composite material laying layer; Step 3.2, check the sealing of plastic bonding. If the sealing is OK, push the composite parts into the autoclave via a trailer and close the autoclave door; Step 3.3, hot pressing: first heat the autoclave to 60°C, keep it warm for 30 minutes, then heat it to 95°C, keep it warm for 30 minutes, pressurize it to 0.6MPa after the heat preservation, heat it to 120°C simultaneously, keep it warm and pressurize it for 90 minutes, finally cool it down to 60°C and reduce the pressure to 0MPa, and the heating and cooling rates are both 5°C / min; Step 3.4, taking out the structure formed in the autoclave and demoulding; Step 4: Bonding of structural parts Bond the box body and cover body structure parts obtained in step 3 with structural adhesive to form a closed box body; Step 5: Secondary paving work Step 5.1, prepare a single layer of carbon fiber cloth, and alternately lay it on the closed box obtained in step 4 according to the requirements of the drawing and the direction of the composite material. The directions of the composite material are 0° and 90° respectively. It can be laid in combination with 45° and other directions according to the actual needs of the product. The number of laying layers = 2 / 3 of the total thickness of the part ÷ the thickness of the single layer; Step 5.2: During the paving process, the direction in which the scraper flattens the composite material should be consistent with the direction of the fibers. To prevent the carbon fiber cloth from folding at corners and other locations with sudden changes in shape, it is necessary to cut them apart and pave them separately. Reinforcing fiber cloth is required at the cut locations, and the edges of structural parts and other reinforced locations should ensure that the carbon fibers overlap to increase the strength of the local locations.

6. The method for manufacturing a composite fuel tank according to claim 5, characterized in that: The total thickness of the box body is 3mm, and the total thickness of the cover body is 3mm.

7. The method for manufacturing a composite fuel tank according to claim 5, characterized in that: The structural adhesive is a high temperature resistant epoxy structural adhesive.

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