Novel light-weight small-size fuel tank for unmanned aerial vehicle and manufacturing method thereof

Abstract

The invention relates to a novel light-weight small-size fuel tank for an unmanned aerial vehicle and a manufacturing method thereof. The invention provides a novel light-weight small-size fuel tank for an unmanned aerial vehicle. The novel light-weight small-size fuel tank comprises a fuel tank large-opening rotary body, a fuel tank lower cover plate and a fuel tank air inlet channel. The oil tank large-opening revolving body comprises an anti-shaking plate and a reinforcing rib structure; the oil tank lower cover plate is located below the oil tank large-opening rotary body, and one end of the oil tank air inlet channel extends into the oil tank large-opening rotary body. The oil tank large-opening revolving body, the oil tank lower cover plate and the oil tank air inlet channel are sealed in a rubber screw mode. The invention further provides a manufacturing method suitable for the novel light-weight small-size fuel tank for the unmanned aerial vehicle. The manufacturing method comprises the steps that the fuel tank large-opening rotary body is formed; forming an oil tank lower cover plate; an oil tank air inlet channel is formed; the oil tank large-opening rotary body, the oil tank lower cover plate and the oil tank air inlet channel are combined; and the anti-shaking plate, the wall plate and the reinforcing ribs are installed.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite material fuel tank forming processes, and more specifically relates to a fuel tank for a new type of lightweight small-sized unmanned aerial vehicle and a manufacturing method thereof. Background Art

[0002] Theoretically, small-sized unmanned aerial vehicles have advantages such as high speed, strong coordination, good concealment, and low cost, and have received great attention from the world's major military powers. Among them, the issue of lightweight has always been the focus of attention for unmanned aerial vehicles, and weight reduction has a particularly obvious impact on various aspects of performance. In recent years, carbon fiber composite materials, as an advanced aerospace material, have been widely used in the field of unmanned aerial vehicle manufacturing due to their lightweight and high-strength characteristics, achieving lightweight development.

[0003] The fuel tank is an important part of the aviation fuel system. Most traditional fuel tanks are metal fuel tanks, but they have problems such as easy corrosion, oil leakage at the welds, and relatively large overall weight. Composite material fuel tanks have advantages such as light weight, strong corrosion resistance, high safety, simple manufacturing, and low production costs, which can make up for the deficiencies brought by metal fuel tanks. At present, domestic composite material fuel tanks are in the initial stage, and in particular, the complex small-sized composite material integral fuel tank for unmanned aerial vehicles with functions of oil storage, sealing, engine air intake, and structural load-bearing integrated is still a blank field. Summary of the Invention

[0004] The purpose of the present invention is to manufacture a composite material fuel tank for a small-sized unmanned aerial vehicle with complex internal structures that combines sealing and load requirements. According to the shape characteristics, sealing requirements, internal structure, and force forms, each component is reasonably divided into types, and finally integrated with all functions. The method of the present invention can not only ensure the lightweight and sealing requirements of the fuel tank itself, but also share the structural loads of the unmanned aerial vehicle during boost, hanging, and high and low temperature cycles, improve production efficiency, and reduce production costs.

[0005] The first aspect of the present invention provides a fuel tank for a new type of lightweight small-sized unmanned aerial vehicle, comprising:

[0006] A large-open-mouth rotary body of the fuel tank, a lower cover plate of the fuel tank, and an air intake duct of the fuel tank; the large-open-mouth rotary body of the fuel tank includes an anti-slosh plate and a stiffening rib structure; the lower cover plate of the fuel tank is located below the large-open-mouth rotary body of the fuel tank, and one end of the air intake duct of the fuel tank extends into the interior of the large-open-mouth rotary body of the fuel tank; the large-open-mouth rotary body of the fuel tank, the lower cover plate of the fuel tank, and the air intake duct of the fuel tank are sealed in a form of glue and screws.

[0007] Furthermore, there are π-shaped, square, flanged, boss, and rib plate structures inside the large-open-mouth rotary body of the fuel tank.

[0008] Furthermore, the forming structure of the fuel tank is in the form of an inner skin, a variable-thickness area, a thickened area, and a skin from the inside to the outside.

[0009] Further, the thickness of the inner skin is 1.8 - 2.4 mm, and the thickness of the outer skin is 1.8 - 2.4 mm.

[0010] Further, the forming materials of the fuel tank include fiber - reinforced resin prepreg, film adhesive, and adhesive solution.

[0011] The second aspect of the present invention provides a manufacturing method for a fuel tank applicable to the above - mentioned new lightweight small - size unmanned aerial vehicle, including:

[0012] Forming a large - opening rotary body of the fuel tank;

[0013] Forming a lower cover plate of the fuel tank;

[0014] Forming an air inlet duct of the fuel tank;

[0015] Combining the large - opening rotary body of the fuel tank, the lower cover plate of the fuel tank, and the air inlet duct of the fuel tank;

[0016] Installing an anti - sloshing plate, wall panels, and reinforcing ribs.

[0017] Further, the large - opening rotary body of the fuel tank, the lower cover plate of the fuel tank, and the air inlet duct of the fuel tank are formed by a mold.

[0018] Further, the large - opening rotary body of the fuel tank, the lower cover plate of the fuel tank, and the air inlet duct of the fuel tank are formed by embedded blocks.

[0019] Further, the embedded blocks include embedded square blocks, embedded diamond - shaped blocks, and embedded cylindrical blocks.

[0020] Further, the total thickness of the embedded square blocks and the embedded diamond - shaped blocks is 10 - 15 mm, and the total thickness of the embedded cylindrical blocks is 8 - 12 mm.

[0021] The beneficial effects of the present invention are as follows:

[0022] (1) The present invention innovatively proposes a composite material integral for a complex small - size unmanned aerial vehicle with functions of oil storage, sealing, engine air intake, and structural load - bearing integrated. By forming parts in different cabin sections, thickening the stress area of the rotary body, adhesively bonding reinforcing ribs at the skin area, and then assembling and sealing step by step, optimizing the sealing gap, it solves the problem of great assembly difficulty of the composite material fuel tank with complex internal structures, greatly improves the production efficiency, and at the same time has a considerable degree of tolerance to load conditions such as tension, compression, bending, and torsion of the fuel tank, making it a reality that the composite material fuel tank of the unmanned aerial vehicle replaces the metal fuel tank, reducing the weight and increasing the flight range.

[0023] (2) The overall sealing design of the composite material integral fuel tank for small - size unmanned aerial vehicles provided by the present invention has strong reliability and a high oil leakage passing rate, providing reference and significance for the manufacture of the same type of composite material fuel tanks. Brief Description of the Drawings

[0024] Figure 1 Schematic diagram of the composite material fuel tank of the present invention.

[0025] Figure 2 Flow chart of the method of the present invention.

[0026] Figure 3 Top view of the large open-mouth rotary body mold of the composite material fuel tank of the present invention.

[0027] Figure 4 Cross-sectional view of the large open-mouth rotary body mold of the composite material fuel tank of the present invention.

[0028] Figure 5 Schematic diagram of the pre-embedded square block of the present invention.

[0029] Figure 6 Top view of the lower cover plate mold of the composite material fuel tank of the present invention.

[0030] Figure 7 Cross-sectional view of the lower cover plate mold of the composite material fuel tank of the present invention.

[0031] Figure 8 Schematic diagram of the pre-embedded cylindrical block of the present invention.

[0032] Figure 9 Top view of the air inlet duct mold of the composite material fuel tank of the present invention.

[0033] Figure 10 Cross-sectional view of the air inlet duct mold of the composite material fuel tank of the present invention.

[0034] Figure 11 Schematic diagram of the pre-embedded rhombic block of the present invention.

[0035] Figure 12 Schematic diagram of the anti-slosh baffle of the present invention.

[0036] Figure 13 Top view of the reinforcing rib of the present invention.

[0037] Figure 14 Side view of the reinforcing rib of the present invention.

[0038] Figure 15 Cross-sectional view of the large open-mouth rotary body structure of the composite material fuel tank of the present invention.

[0039] Description of the reference numerals

[0040] 0. Pre-embedded square block reserved position; 1. Composite fuel tank large open rotating body; 2. Composite fuel tank lower cover; 3. Composite fuel tank air intake; 4 Rotating body mold pressure screw; 5 Rotating body mold upper cover; 6 Rotating body mold lower cover; 7 Rotating body mold outer side strip; 8 Rotating body mold inner side strip; 9 Rotating body mold front forming core block; 10 Rotating body mold rear forming core block; 11 Rotating body mold rear side strip; 12 Rotating body mold front side strip strip; 13 lower cover plate mold upper cover plate; 14 lower cover plate mold lower cover plate; 15 lower cover plate mold front strip; 16 lower cover plate mold rear strip; 17 lower cover plate mold forming core block; 18 reserved position for embedded columnar block; 19 lower cover plate mold pressure screw; 20 upper cover plate of air inlet mold; 21 lower cover plate of air inlet mold; 22 front baffle of air inlet mold; 23 rear baffle of air inlet mold; 24 air inlet mold forming core block; 25 reserved position for embedded block diamond. 26 internal flange structure; 27 internal π-shaped structure; 28 internal square structure; 29 internal boss structure; 30 internal rib plate structure. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] The following describes a novel lightweight small-sized composite material integral fuel tank molding process technology for UAVs according to the present invention in conjunction with the accompanying drawings.

[0043] The first aspect of the embodiment of the present invention discloses the structure of the composite material integral fuel tank of the present invention, such as Figure 1 As shown, it includes a large open rotating body of the fuel tank, a lower cover plate of the fuel tank, and an air inlet duct of the fuel tank; the large open rotating body of the fuel tank includes an anti-sway plate and a reinforcing rib structure; the lower cover plate of the fuel tank is located below the large open rotating body of the fuel tank, and one end of the air inlet duct of the fuel tank extends into the interior of the large open rotating body of the fuel tank; the large open rotating body of the fuel tank, the lower cover plate of the fuel tank and the air inlet duct of the fuel tank are sealed by means of rubber screws.

[0044] In this embodiment, the large open rotating body of the composite fuel tank optimizes the topological space structure according to the sealing requirements. There are π-shaped, square, flanged, boss and rib plate structures inside. The anti-sway plate, wall plate and reinforcement ribs are post-bonded to reduce the difficulty of fuel tank molding. The overall rigid structure of the fuel tank and the post-bonded reinforcement ribs inside the fuel tank improve the pressure resistance of the fuel tank on the one hand, and save space and increase the fuel endurance on the other hand.

[0045] In this embodiment, the forming material system of the composite material fuel tank includes fiber reinforced resin prepreg (unidirectional, carbon cloth), adhesive film and adhesive liquid. The fiber is carbon fiber, and the type of fiber is selected according to the product structure characteristics and design load, such as one of T700 grade, T800 grade, and T1100 grade. The form of the reinforcing fabric can be one of T800-6k, T300-3k, T700-3k, CF8611 plain fabric and twill fabric. The type of resin can be one of 9368, 8522, 8210, 3234, 3221, 6808, 9A16. The adhesive film is one of J-47A, J-78B, J-95, 271B and HDG-01. The adhesive liquid is one of J-47B, J-22, J-139.

[0046] In this embodiment, the forming structure form of the composite material fuel tank is inner skin + variable thickness area + thickening area + outer skin. The thickness of the inner skin of the large open-mouth rotating body of the composite material fuel tank is 1.8 - 2.4 mm, and the thickness of the outer skin is 1.8 - 2.4 mm; the thickness of the inner skin of the lower cover plate of the composite material fuel tank is 1.8 - 2.4 mm; the thickness of the inner skin of the air inlet duct of the composite material fuel tank is 1.8 - 2.4 mm; the total thickness of the reinforcing ribs, anti-slosh plates and wall plates is 1 - 2.5 mm, the total thickness of the embedded square blocks and embedded diamond blocks is 10 - 15 mm, and the total thickness of the embedded cylindrical blocks is 8 - 12 mm.

[0047] The second aspect of the present invention discloses a manufacturing method of the composite material integral fuel tank of the present invention, and the specific process is as Figure 2 shown. The manufacturing method mainly includes the following steps:

[0048] (1) Precast square blocks, cylindrical blocks and diamond blocks. Before use, the surface of the precast blocks needs to be polished, and a layer of adhesive liquid J-147B is evenly brushed on their surfaces.

[0049] (2) Form the large open-mouth rotating body of the composite material fuel tank. The forming of the embedded square blocks is included in the large open-mouth rotating body of the composite material fuel tank, and a fuel pipe opening is reserved.

[0050] (3) Form the lower cover plate of the composite material fuel tank. The forming of the embedded cylindrical blocks is included in the lower cover plate of the composite material fuel tank.

[0051] (4) Form the air inlet duct of the composite material fuel tank. The forming of the embedded diamond blocks is included in the air inlet duct of the composite material fuel tank.

[0052] (5) Evolve the assembly using the glue-screw connection method. The screw is an M4 countersunk head screw, and the nut uses an airtight double-ear tray nut. Fix the lower cover plate and the air intake duct to the large open-ended composite material fuel tank rotating body in a screwed manner, and seal it in a fillet seal form. Install a fuel pipe from the air intake duct to the large open interior of the composite material fuel tank. The fuel pipe is made of 6061 aluminum, and the adhesive is J-133C and HM112 sealant adhesive.

[0053] (6) Grind the surfaces of the anti-slosh plate, the wall plate, and the precast block of the stiffener, and clean them with alcohol or acetone. Use J-133C to bond the anti-slosh plate, the wall plate, and the stiffener at the scribed line positions, and at the same time clean the interior of the fuel tank of foreign objects.

[0054] This embodiment discloses a detailed forming method for the large open-ended composite material fuel tank rotating body in the above step (1).

[0055] (Ⅰ) According to the internal structure, external shape characteristics, and stress form of the fuel tank product, taking into account the laying process and forming method, comprehensively calculating the strength and establishing a three-dimensional model, design a forming mold. The accuracy of the mold is 0 - 0.1 mm, the mold material uses P20 steel, and the surface roughness Ra of the mold forming surface is ≤ 0.8 μm. Please refer to Figure 3 、 Figure 4 , the forming mold includes the upper cover plate 5 of the rotating body mold, the upper cover plate 6 of the rotating body mold, the rear side strip 11 of the rotating body mold, the front side strip 12 of the rotating body mold, the outer side strip 7 of the rotating body mold, the inner side strip 8 of the rotating body mold, the front forming core block 9 of the rotating body mold, the rear forming core block 10 of the rotating body mold, and the pressure screw 4 of the rotating body mold; the forming core blocks are laid separately and then closed and laid as a whole. After all the laying is completed, the mold is closed by the upper cover plate 6 of the rotating body mold; the forming of the anti-slosh plate, the wall plate, the ribs, and the embedded square block ensures the strength of the fuel tank and is used for the complex internal structure of the fuel tank.

[0056] (Ⅱ) According to the product characteristics and load-bearing requirements of the forming material, select T300 grade plain weave carbon cloth / 9368 prepreg, T700 grade unidirectional carbon fiber / 9368 prepreg, J-47B adhesive solution, and J-47A medium-temperature adhesive film with good laying performance; the forming structure form of the large open-ended composite material fuel tank rotating body in this embodiment is inner skin + variable thickness area + thickened area + outer skin. The thickness of the inner skin of the large open-ended composite material fuel tank rotating body is 1.8 - 2.4 mm, preferably 2 mm; the thickness of the outer skin is 1.8 - 2.4 mm, preferably 2 mm; the thickness of the embedded square block is 10 - 15 mm, preferably 12 mm.

[0057] (Ⅲ) Unfold and lay out the prepreg of the product through three-dimensional digital modeling software, optimize the layout design of the cutting template using AutoCAD, then cut the material using a numerical control cloth cutting machine, mark the laid-up shaped prepreg and stack it.

[0058] (Ⅳ) Clean the die blocks of the manufactured mold, apply a medium-temperature mold release agent on the surface, and assemble each die block according to the number.

[0059] (Ⅴ) Lay the inner skin, J-47A medium-temperature film adhesive, reinforcing ribs, variable thickness area, thickening area, and outer skin on the front forming core block 9 of the rotary body mold and the rear forming core block 10 of the rotary body mold in sequence. Place the embedded square block at the reserved position 0 of the embedded square block. Before laying the inner skin in the mold, it is necessary to lay two layers of reinforcing fabric, and at the same time lay a film adhesive with a thickness of 0.1 - 0.2 mm outside the fabric. The inner skin is laid with a single-filament prepreg. After laying the outer skin, it is necessary to lay a layer of reinforcing fabric. After laying the inner and outer skins and the embedded block, perform vacuum pre-compaction once each, with a vacuum degree not less than 0.095 MPa and a temperature of 50 ± 5 °C to form a fully wrapped composite material layer; the embedded square block is as Figure 5 shown.

[0060] (Ⅵ) After laying is completed, perform a pre-pressing, and plug the material-deficient areas according to the pre-pressing results.

[0061] (Ⅶ) Close the mold: After laying is completed, buckle the upper cover plate 6 onto the mold, place the closed mold in an oven, set the oven temperature to 90 °C ± 5 °C, keep it warm for 30 min, check the mold closing gap, tighten the pressure screw 4 of the rotary body mold to ensure that the mold closing gap ≤ 0.2 mm until the mold closing gap is satisfied, and complete the mold closing.

[0062] (Ⅷ) Curing and forming: Set the oven temperature to 135 ± 5 °C and cure for 2 h.

[0063] (Ⅸ) Demold and trim: After curing is completed, open the upper cover plate 6 of the rotary body mold, remove the core block in the mold, take out the product and trim the flash to obtain the large open-mouth rotary body 1 of the composite material fuel tank.

[0064] This embodiment discloses a detailed forming method of the composite material fuel tank lower cover plate in the above step (3).

[0065] (Ⅰ) According to the internal structure, external shape characteristics, and stress form of the fuel tank product, taking into account the laying process and forming method, through comprehensive strength calculation and three-dimensional model establishment, design a forming mold with a mold accuracy of 0 - 0.1 mm. The mold material is P20 steel, and the surface roughness Ra of the mold forming surface ≤ 0.8 μm. Please refer to Figure 6 、 Figure 7 , the forming mold includes the upper cover plate 13 of the lower cover plate mold, the lower cover plate 14 of the lower cover plate mold, the front strip 15 of the lower cover plate mold, the rear strip 16 of the lower cover plate mold, the left and right side strips of the lower cover plate mold (not marked in the figure), and the forming core block 17 of the lower cover plate mold; after laying is completed on the forming core block 17 of the lower cover plate mold, the mold is closed by the upper cover plate 13 of the lower cover plate mold.

[0066] (Ⅱ) For the molding material, according to the product characteristics and load-bearing requirements, select T300 plain carbon cloth / 9368 prepreg with good laying performance, T700 unidirectional carbon fiber / 9368 prepreg, J-47B adhesive, and J-47A medium-temperature adhesive film; the molding structure of the composite fuel tank lower cover plate is inner skin + variable thickness area + thickened area + outer skin. The thickness of the inner skin of the composite fuel tank lower cover plate is 1.8 - 2.4 mm, preferably 2 mm, and the thickness of the embedded cylindrical block is 8 - 12 mm, preferably 8 mm.

[0067] (Ⅲ) Use 3D digital modeling software to perform unfolding and nesting of the prepreg for the product, optimize the layout design of the cutting template using AutoCAD, then cut the material using a numerical control cloth cutting machine, mark the laying layers on the cut conforming prepreg, and stack them.

[0068] (Ⅳ) Clean the modular blocks of the manufactured mold, apply a medium-temperature mold release agent on the surface, and assemble the modular blocks of each mold.

[0069] (Ⅴ) On the forming core block 17 of the lower cover plate mold, lay the inner skin, J-47A medium-temperature adhesive film, variable thickness area, and outer skin in sequence, and place the embedded cylindrical block at the reserved position 18 for the embedded cylindrical block. Before laying the inner skin in the mold, it is necessary to lay two layers of reinforcing fabric, and at the same time lay a layer of adhesive film with a thickness of 0.1 - 0.2 mm outside the fabric. The inner skin is laid with single-filament prepreg. After laying the outer skin, it is necessary to lay a layer of reinforcing fabric. After laying the inner and outer skins and the cylindrical block, perform vacuum pre-compaction once each, with the vacuum degree not less than 0.095 MPa and the temperature at 50 ± 5 °C, to form a fully wrapped composite material layer; the embedded cylindrical block enters Figure 8 as shown.

[0070] (Ⅵ) After laying is completed, perform a pre-pressing, and plug the areas with insufficient material according to the pre-pressing results.

[0071] (Ⅶ) Curing and molding: Fasten the upper cover plate 13 of the lower cover plate mold to the mold, place the closed mold on the press, set the temperature to 90 °C ± 5 °C, keep warm for 30 min, apply a pressure of 10 MPa, check the mold closing gap, ensure that the mold closing gap ≤ 0.2 mm, until the mold closing gap is satisfied, set the press temperature to 135 ± 5 °C, and cure for 2 h.

[0072] (Ⅷ) Demolding and trimming: After curing, open the upper cover plate, remove the inner core block in the mold, take out the product for flash trimming to obtain the composite fuel tank lower cover plate.

[0073] This embodiment discloses a detailed molding method for the composite fuel tank air inlet duct in the above step (4).

[0074] (Ⅰ) According to the internal structure, external shape characteristics, and force-bearing form of the fuel tank product, taking into account the laying process and forming method, and integrating strength calculation and three-dimensional model establishment, design the forming mold. Please refer to Figure 9 、 Figure 10 . The forming mold includes an upper cover plate 20 of the air inlet duct mold, a lower cover plate 21 of the air inlet duct mold, a front baffle 22 of the air inlet duct mold, a rear baffle 23 of the air inlet duct mold, left and right side strips of the air inlet duct mold (not marked in the figure), left and right limit blocks of the air inlet duct mold (not marked in the figure), a forming core block 24 of the air inlet duct mold, and a pressure screw 19 of the air inlet duct mold. After the laying is completed on the forming core block 24 of the air inlet duct mold, the mold is closed by the upper cover plate 20 of the air inlet duct mold.

[0075] (Ⅱ) According to the product characteristics and load-bearing requirements, select T300 grade plain weave carbon cloth / 9368 prepreg, T700 grade unidirectional carbon fiber / 9368 prepreg, J-47B adhesive solution, and J-47A medium-temperature adhesive film with good laying performance as the forming materials; the forming structure form of the lower cover plate of the composite material fuel tank is inner skin + variable thickness area + thickened area + outer skin. The thickness of the inner skin of the air inlet duct of the composite material fuel tank is 1.8 - 2.4 mm, preferably 2 mm, and the thickness of the embedded diamond block is 10 - 15 mm, preferably 15 mm.

[0076] (Ⅲ) Use three-dimensional digital modeling software to unfold and layout the prepreg of the product, optimize the layout design of the cutting template using AutoCAD, then cut the material using a numerical control cloth cutting machine, mark the laid-up shaped prepreg and stack them.

[0077] (Ⅳ) Clean the component blocks of the manufactured mold, apply medium-temperature mold release agent on the surface, and assemble the component blocks of each mold.

[0078] (Ⅴ) Lay the inner skin, J-47A medium-temperature adhesive film, variable thickness area, and outer skin on the forming core block 24 of the air inlet duct mold in sequence, and place the embedded diamond block at the reserved position 25 for the embedded diamond block. Before laying the inner skin in the mold, two layers of reinforcing fabric need to be laid, and at the same time, a layer of adhesive film with a thickness of 0.1 - 0.2 mm is laid outside the fabric. The inner skin is laid with single-filament prepreg. After laying the outer skin, a layer of reinforcing fabric needs to be laid. After laying the inner and outer skins and the columnar block, vacuum pre-compaction is carried out once each, with the vacuum degree not less than 0.095 MPa and the temperature at 50 ± 5 °C to form a fully wrapped composite material lay-up; the embedded columnar block enters Figure 11 as shown.

[0079] (Ⅵ) After laying is completed, conduct a pre-press, and plug the material-deficient areas according to the pre-press results.

[0080] (Ⅶ) Mold closing: After laying is completed, fasten the upper cover plate 20 of the intake duct mold onto the mold. Place the closed mold in an oven, set the oven temperature to 90°C ± 5°C, keep it warm for 30 minutes, check the mold closing gap, tighten the pressure screw 19 of the intake duct mold, ensure that the mold closing gap ≤ 0.2 mm, until the mold closing gap is met, and complete the mold closing.

[0081] (Ⅷ) Curing and forming: Set the oven temperature to 135 ± 5°C and cure for 2 hours.

[0082] (Ⅸ) Demolding and trimming: After curing, open the upper cover plate 20 of the intake duct mold, remove the core block inside the mold, take out the product and perform flash trimming to obtain the composite material fuel tank intake duct 3.

[0083] This embodiment discloses the detailed method of assembly in the above step (5). The operating environment is carried out in a sealed and clean space to prevent foreign matters from entering the fuel tank.

[0084] (Ⅰ) After obtaining the composite material fuel tank intake duct 3, grind all the bonding surfaces, clean them with acetone. Use M4 countersunk head screws and M4 airtight double-ear tray nuts for the nuts. Fix them on the large open-ended rotary body 1 of the composite material fuel tank by riveting, and seal them in the form of fillet sealing, so that the intake duct is connected to the corresponding positioning scale line position of the large open-ended rotary body 1 of the composite material fuel tank. At the same time, clean the excess glue nodules and debris, ensure that the plane has no burrs, and then install the oil pipe. The end of the oil pipe nozzle is located at the highest point of the fuel tank. The surface of the oil nozzle is provided with a pagoda head and a filter screen, and is fixedly connected to the inner side wall of the fuel tank through a fixing rod. Tighten the inner and outer nuts for fixing the oil pipe and further fix the oil pipe with a locking screw.

[0085] (Ⅱ) Grind all the bonding surfaces, clean them with acetone. Uniformly apply the bonding glue HM112 sealing adhesive and J-133C in the overlapping area between the large open-ended rotary body 1 of the composite material fuel tank and the lower cover plate. At the same time, clean the excess glue and ensure that the plane has no burrs.

[0086] (Ⅲ) Steadily fasten the lower cover plate 2 of the composite material fuel tank onto the composite material fuel tank, ensure that the overlapping area is completely butted and at the same time ensure that the bonding glue can be extruded from the overlapping seam. At the same time, clean the excess glue nodules and debris, ensure that the plane has no burrs.

[0087] (Ⅳ) Control the sealing gap, use a positioning tooling along the length direction of the fuel tank and the method of using straps to apply pressure for curing the bonding glue. The pressure application direction is kept perpendicular to the bonding surface to ensure that the thickness of the glue layer is consistent, and the extruded excess glue is removed in time.

[0088] (Ⅴ) Pressure relief and trimming: After curing, grind and trim the bonding area.

[0089] This embodiment discloses the post-bonding method of the anti-slosh plate, stiffening rib, and wall plate in the above step (6). The operation environment is carried out in a sealed and clean space to prevent foreign objects from entering the fuel tank.

[0090] (Ⅰ) Pre-fabricate the anti-slosh plate, stiffening rib, and wall plate. The total thickness of the stiffening rib, anti-slosh plate, and wall plate is 1 - 2.5 mm, preferably 1.5 mm. Before use, the surface of the prefabricated block needs to be polished and cleaned with acetone. Apply the bonding adhesive J-133C evenly in the scribed bonding area, and at the same time, clean the excess glue nodules and debris to ensure that the plane has no burrs. The structure of the anti-slosh plate is as Figure 12 shown, and the structure of the stiffening rib is as Figure 13 and Figure 14 shown. Please refer to Figure 15 , Figure 15 which shows the cross-sectional structure of the large open-ended composite fuel tank of the unmanned aerial vehicle after bonding the anti-slosh plate, stiffening rib, and wall plate, including the internal flanging structure 26, internal π-shaped structure 27, internal square structure 28, internal boss structure 29, and internal rib structure 30.

[0091] (Ⅱ) Trimming: After curing, polish and trim the scribed bonding area.

[0092] After oil penetration and airtightness performance testing, a new type of lightweight and small-sized composite fuel tank for unmanned aerial vehicles manufactured by the present invention fully meets the usage requirements. The relevant test results of the fuel tank are shown in Table 1.

[0093] Table 1

[0094]

[0095] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that not every embodiment only contains an independent technical solution. In the case of no conflict between the solutions, the technical features mentioned in each embodiment can be combined in any way to form other embodiments that can be understood by those skilled in the art.

[0096] In addition, without departing from the scope of the present invention, modifying the technical solutions recorded in the foregoing embodiments, or equivalently replacing some of the technical features, does not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of each embodiment of the present invention.

Claims

1. A fuel tank for a new type of lightweight and small-sized unmanned aerial vehicle, comprising: A large-open-mouth rotary body of the fuel tank, a lower cover plate of the fuel tank, and an air inlet duct of the fuel tank; the large-open-mouth rotary body of the fuel tank includes an anti-slosh plate and a stiffening rib structure; the lower cover plate of the fuel tank is located below the large-open-mouth rotary body of the fuel tank, and one end of the air inlet duct of the fuel tank extends into the interior of the large-open-mouth rotary body of the fuel tank; the large-open-mouth rotary body of the fuel tank, the lower cover plate of the fuel tank, and the air inlet duct of the fuel tank are sealed in a glue-screw form.

2. The fuel tank according to claim 1, wherein Inside the large-open-mouth rotary body of the fuel tank, there are π-shaped, square, flanging, boss, and rib plate structures.

3. The fuel tank according to claim 1, characterized in that, The forming structure of the fuel tank is, from the inside to the outside, an inner skin, a variable-thickness area, a thickening area, and a skin.

4. The fuel tank according to claim 3, characterized in that, The thickness of the inner skin is 1.8 - 2.4 mm, and the thickness of the outer skin is 1.8 - 2.4 mm.

5. The fuel tank according to claim 1, characterized in that, The forming materials of the fuel tank include fiber-reinforced resin prepreg, adhesive film, and adhesive liquid.

6. A manufacturing method for the fuel tank according to any one of claims 1 - 5, comprising: Forming the large-open-mouth rotary body of the fuel tank; Forming the lower cover plate of the fuel tank; Forming the air inlet duct of the fuel tank; Combining the large-open-mouth rotary body of the fuel tank, the lower cover plate of the fuel tank, and the air inlet duct of the fuel tank; Installing the anti-slosh plate, wall plate, and stiffening ribs.

7. The method according to claim 6, wherein The large-open-mouth rotary body of the fuel tank, the lower cover plate of the fuel tank, and the air inlet duct of the fuel tank are formed by a mold.

8. The method according to claim 7, characterized in that, The large-open-mouth rotary body of the fuel tank, the lower cover plate of the fuel tank, and the air inlet duct of the fuel tank are formed by embedded blocks.

9. The method according to claim 8, wherein The embedded blocks include embedded square blocks, embedded diamond blocks, and embedded cylindrical blocks.

10. The method according to claim 9, wherein The total thickness of the embedded square blocks and the embedded diamond blocks is 10 - 15 mm, and the total thickness of the embedded cylindrical blocks is 8 - 12 mm.

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