Missile composite fuel tank and method of forming same

Abstract

The application provides a missile composite fuel tank and a forming method thereof. The outer shell of the fuel tank is a part of a missile body, and comprises an upper front skin, an upper rear skin, a lower skin, a middle cover plate, front and rear end frames, an internal partition, a reinforcing rib, internal pipelines and a buried part. The upper front skin, the upper rear skin, the lower skin and the reinforcing rib are carbon fiber composite material structures, the internal partition is a carbon fiber foam sandwich structure, the middle cover plate and the front and rear end frames are alloy structures, the middle cover plate, the lower skin and the front end frame are connected through a double mode of gluing and screwing, the internal partition divides the fuel tank into multiple relatively independent cabins, different cabins maintain air tightness in structure, the reinforcing rib is used for improving the rigidity of the fuel tank and bearing internal pressure, and the front and rear end frames are used for being connected with front and rear equipment. The application realizes a structural and functional integrated composite fuel tank for a missile, which meets the sealing oil storage function of the fuel tank, and also meets the strength and rigidity requirements in the flight of the missile body.

Description

Technical Field

[0001] This invention relates to the field of molding technology for composite material components of missiles, specifically to a composite material fuel tank for missiles and its molding method, and more particularly to an integrated composite material structure of missile body and fuel tank and its molding method. Background Technology

[0002] Missile fuel tanks are specially designed compartments within the missile body to store fuel and power the missile. Traditional missile fuel tanks are made of aluminum alloy, which is relatively heavy. However, composite materials have advantages such as high specific modulus, high specific strength, impact resistance, creep resistance, seismic resistance, and strong design flexibility. They can achieve lightweight structures while meeting structural performance requirements. Therefore, in the fields of aviation, aerospace, and weaponry, component structures are gradually shifting from traditional metal materials to fiber-reinforced resin matrix composites.

[0003] In view of the problems existing in the traditional missile fuel tank with aluminum alloy structure, there is an urgent need to develop a missile fuel tank with composite material structure, so as to meet the functions of sealing and storing fuel tank while also meeting the strength and rigidity requirements of missile body during flight. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a missile composite fuel tank and its molding method.

[0005] The missile composite fuel tank provided by the present invention includes an upper front skin, an upper rear skin, a lower skin, a middle cover plate, a front end frame, and a rear end frame. The upper front skin, the middle cover plate, and the upper rear skin are connected sequentially from front to back and are all installed on the upper part of the lower skin to form a compartment structure. The front end frame and the rear end frame are respectively installed at the front and rear ends of the compartment structure.

[0006] The middle cover plate, front frame, and rear frame all serve as connection structures to external equipment and are integrally formed from metal. The upper front skin, upper rear skin, and lower skin are formed by laying composite materials.

[0007] Preferably, the compartment structure has multiple partitions inside, dividing the entire compartment into multiple sub-compartments. Among the multiple sub-compartments, the sub-compartment at the front end is provided with a refueling port, and the sub-compartment at the rear end is provided with an exhaust port.

[0008] Preferably, each of the sub-compartments is provided with a reinforcing rib and an inspection window, and the inspection window is movably provided with an inspection cover;

[0009] The fuel tank is equipped with a semi-open, semi-sealed embedded part that connects to the outside.

[0010] Preferably, the middle cover plate, the front frame, and the rear frame are all integrally formed from 7075-T651 aluminum alloy.

[0011] Preferably, the upper front skin, upper rear skin, lower skin, and inspection cover are all made of T300 grade carbon fiber composite material.

[0012] The reinforcing ribs are made of T800 grade carbon fiber composite material.

[0013] The partition frame adopts a carbon fiber PMI foam sandwich structure.

[0014] Preferably, the ratio of the quasi-isotropic layup angles in the upper front skin, upper rear skin, lower skin, and inspection cover is [(0° / 90°) / (±45°)]=1:2;

[0015] The thickness ratio of carbon fiber to foam in the partition frame is 4:11, and the layup angle ratio of carbon fiber is [(0° / 90°) / (±45°)]=1:1.

[0016] Preferably, each carbon fiber structure in the fuel tank adopts a quasi-isotropic layup, and the layup angle is a combination of 0°, ±30°, ±45°, ±60° and 90°.

[0017] Preferably, there are assembly gaps between the structural assembly surfaces of each component in the fuel tank, and the assembly surfaces of adjacent components are connected by both adhesive bonding and screw bonding. The adhesive bonding uses rich adhesive filling, and the screw bonding uses countersunk screws with adhesive bonding.

[0018] Preferably, the upper front skin, upper rear skin, lower skin, and the surface of the partition frame are all coated with body resin.

[0019] The molding method for a missile composite fuel tank according to the present invention, used for molding the missile composite fuel tank, includes the following steps:

[0020] S1: The upper front skin, upper rear skin, lower skin and reinforcing ribs are pre-formed by carbon fiber layup, and the partition frame is pre-formed by carbon fiber and foam sandwich layup, and then cured by pressurization and heating in a hot autoclave.

[0021] S2: Apply body resin to both sides of the partition frame, the inner surface of the upper front skin, the inner surface of the upper rear skin, and the inner surface of the lower skin.

[0022] S3: The upper front skin, upper rear skin, lower skin, reinforcing rib, partition, front end frame, rear end frame and middle cover plate are connected together by adhesive bonding and screwing. The adhesive bonding adopts rich glue extrusion bonding, and the bolts adopt countersunk screws and are screwed together with glue on the screws.

[0023] S4: After the assembly of each sub-compartment is completed, apply excess adhesive to the joints and press it to solidify. Apply sealant to the inside of each sub-compartment to ensure the overall sealing performance.

[0024] S5: Perform a pressure sealing check on each sub-compartment. If there is any leakage, use adhesive and sealant to reseal the leaking area and then re-inspect.

[0025] S6: Cover the inspection windows of each sub-compartment with inspection covers, which are sealed using a combination of adhesive and screw connections.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The composite fuel tank of the present invention adopts a fully enclosed design, which can maintain full sealing under high internal pressure and provide stable fuel supply in all flight attitudes of missiles, such as dive, pitch, and roll. It adopts a thin-shell, linerless design, which reduces its own weight, improves space utilization, and simplifies the liner molding and assembly process. The composite fuel tank adopts a double sealing layer design of body adhesive and sealant to ensure structural sealing.

[0028] 2. The composite fuel tank of this invention uses a bulkhead to divide the entire tank section into sub-tanks, which can reduce the sloshing of the liquid surface, effectively control the center of gravity of the aircraft, and facilitate the control of flight attitude. The use of reinforcing ribs can greatly improve the circumferential stiffness of the fuel tank and reduce deformation under internal pressure. The use of semi-open and semi-sealed embedded parts design ensures the sealing of the external connection of the tank body and reduces the risk of leakage. The use of inspection opening design ensures the quality measurability and maintainability of the product during the molding process and improves the product qualification rate.

[0029] 3. All composite fuel tank structures of the present invention are made of the same material, and multiple structures can be formed in one batch in a hot autoclave, which greatly reduces the molding time of structural components and is conducive to modular production of products. In terms of structural assembly, a double connection method of glue and screw is adopted, the glue surface is rich in glue to block the leakage path, and the screw connection adopts countersunk sealing glue connection, which improves the internal pressure resistance of the glue surface and ensures the overall connection strength and connection sealing. Attached Figure Description

[0030] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0031] Figure 1 This is a schematic diagram of the overall structure of the fuel tank in this invention;

[0032] Figure 2This is a schematic diagram of the lower skin structure in this invention;

[0033] Figure 3 This is a schematic diagram of the upper rear skin structure in this invention;

[0034] Figure 4 This is a schematic diagram of the upper front skin structure in this invention;

[0035] Figure 5 This is a schematic diagram of the structure of the inspection cap in this invention;

[0036] Figure 6 This is a schematic diagram of the partition frame in the present invention;

[0037] Figure 7 This is a schematic diagram of the reinforcing rib structure in this invention;

[0038] Figure 8 This is a schematic diagram of the semi-open, semi-sealed embedded part in this invention.

[0039] The diagram shows:

[0040] Rear end frame 1, semi-open / semi-sealed embedded part 6

[0041] Upper rear skin 2, check the cover 7

[0042] Middle cover plate 3, lower skin 8

[0043] Upper front skin 4, reinforcing ribs 9

[0044] Front frame 5, partition frame 10 Detailed Implementation

[0045] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0046] In response to the requirements of fuel tanks in terms of sealing, manufacturability, fuel storage capacity, rigidity, and strength, the purpose of this invention is to provide a missile composite material fuel tank and its molding method, thereby achieving the sealing and fuel storage capacity of the fuel tank, while meeting the rigidity and strength requirements of the missile body during takeoff and landing, realizing stable fuel supply and integrity of the missile body structure, and achieving modular, economical, and reliable manufacturing of the product.

[0047] According to the missile composite fuel tank provided by the present invention, such as Figure 1As shown, it includes an upper front skin 4, an upper rear skin 2, a lower skin 8, a middle cover plate 3, a front frame 5, and a rear frame 1; the fuel tank is equipped with a bulkhead 10, which divides the entire compartment into 5 sub-compartments, namely compartment 1, compartment 2, compartment 3, compartment 4, and compartment 5 from front to back. Each sub-compartment is equipped with a reinforcing rib 9 and an inspection window, and the inspection window is equipped with an inspection cover 7; the fuel tank is equipped with a semi-open and semi-sealed embedded part 6 for external connection; fuel tank compartment 1 is equipped with a refueling port, and compartment 5 is equipped with an exhaust port;

[0048] The middle cover plate 3, front frame 5, and rear frame 1 serve as the connection structure with the outside. They are made of 7075-T651 aluminum alloy. The upper front skin 4, upper rear skin 2, lower skin 8, and inspection cover 7 are made of T300 grade carbon fiber composite material. The reinforcing rib 9 is made of T800 grade carbon fiber. The partition frame 10 is made of carbon fiber PMI foam sandwich structure.

[0049] The quasi-isotropic layup angle ratio of the upper front skin 4, upper rear skin 2, lower skin 8, and inspection cover 7 is [(0° / 90°) / (±45°)] = 1:2. The layup thickness ratio of carbon fiber to foam in the bulkhead 10 is 4:11, wherein the layup angle ratio of carbon fiber is [(0° / 90°) / (±45°)] = 1:1. All carbon fiber structures in the fuel tank adopt quasi-isotropic layup, and the layup angle is a combination of 0°, ±30°, ±45°, ±60° and 90°.

[0050] Each structural assembly surface has a 0.6mm assembly gap to facilitate assembly and sealing. The assembly surfaces are connected by both adhesive and screw connections. The adhesive connection uses a rich glue filling method, and the screw connection uses countersunk screws with glue. The surfaces of the upper front skin 4, upper rear skin 2, lower skin 8, and partition 10 are all coated with body resin.

[0051] According to the molding method of the missile composite fuel tank provided by the present invention, the processing and assembly molding of the fuel tank includes the following steps:

[0052] S1: The upper front skin 4, upper rear skin 2, lower skin 8, and reinforcing rib 9 are prefabricated by carbon fiber layup. The partition is prefabricated by carbon fiber and foam interlayer layup and then cured by pressurization and heating in an autoclave. The middle cover plate 3, front frame 5, rear frame 1, and semi-open semi-sealed embedded part 6 are formed by machine processing of whole pieces of rough leather.

[0053] S2: The inner surfaces of the upper front skin 4, upper rear skin 2, and lower skin 8, as well as both sides of the partition frame 10, are coated with 1mm of body resin.

[0054] S3: The upper front skin 4, upper rear skin 2, lower skin 8, reinforcing rib 9, partition frame 10, front frame 5, rear frame 1, and middle cover plate 3 are connected together by adhesive bonding and screwing. The adhesive bonding adopts rich glue extrusion bonding, and the bolts adopt countersunk screws and are screwed together with glue on the screws.

[0055] S4: After each compartment is assembled, apply excess adhesive to the joints and press it to solidify; apply sealant to the interior to ensure overall sealing performance.

[0056] S5: Perform a pressure sealing check on each compartment one by one. If there is any leakage, use adhesive and sealant to reseal the leaking area and check again.

[0057] S6: After the inspection of one compartment is completed, the inspection port cover 7 of one compartment is affixed. The inspection port cover 7 is sealed by a dual connection method of adhesive bonding and screw bonding.

[0058] The above are basic embodiments of the present invention. The following is a preferred embodiment to further illustrate the solution of the present invention.

[0059] This embodiment provides a method for molding a fuel tank with a main body based on composite materials, including the following steps:

[0060] S1. Based on the actual working conditions, quality and dimensional requirements, perform finite element simulation calculations to determine the specifications of the selected composite material, calculate the optimal layup angle and number of layers, and the sandwich method of the foam sandwich structure.

[0061] S2. Lay up the carbon fiber composite material on the mold according to the calculated layup angle and number of layers to form the laminated plate structure components. The layup angle ratio is [(0° / 90°) / (±45°)] = 1:2. Lay up the carbon fiber structure and sandwich foam on the mold according to the designed layup angle and number of layers. The layup thickness ratio of carbon fiber to foam is 4:11, and the layup angle ratio of carbon fiber is [(0° / 90°) / (±45°)] = 1:1.

[0062] S3. Use an autoclave to pressurize and cure the laid-up upper front skin 4, upper rear skin 2, lower skin 8, partition 10, and reinforcing rib 9. The curing temperature of the carbon fiber composite structure is 120℃.

[0063] S4. Fix the lower skin 8 on the mounting platform, pre-assemble each partition, upper front skin 4, upper rear skin 2, reinforcing rib 9, middle cover plate 3, front frame 5, and rear frame 1, check the assembly gap, clarify the assembly sequence and position of each structure, mark the structure with a marker, take photos and make a text description.

[0064] Apply excess adhesive to the bonding surface of the S5 and 3 compartment bulkhead 10, ensure sufficient adhesive on the bonding surface by squeezing, tighten the screws with adhesive, and then fasten the metal cover plate onto compartment 3 for double connection with glue and screws.

[0065] S6. Conduct an airtightness check on compartment 3. If there is any leakage, apply sealant to the outside and conduct another airtightness check until the pressure is maintained at the design pressure for ≥20 minutes and the pressure change value is ≤0.1KPa.

[0066] S7. Starting from the middle and working towards both ends, assemble the piping and skin of compartments 1, 2, 4, and 5 one compartment at a time, and check the airtightness of each compartment through the inspection window to complete the sealing of the inspection window of each compartment.

[0067] S8. Spray paint on the surface of the fuel tank after the adhesive bonding inspection is completed.

[0068] The purpose of this invention is to provide a composite material fuel tank structure and molding method. The missile fuel tank, as part of the missile body and also as a fuel storage device, adopts a full carbon fiber composite material structure, which can not only meet the sealing and fuel storage function of the fuel tank, but also meet the strength and stiffness requirements of the missile body during flight. It achieves the unity of the structure and function of the fuel tank, and reduces the overall weight, leaving sufficient space and weight for the missile's control, reconnaissance, communication, navigation and other equipment. It successfully solves the problem of unifying the functionality of fuel storage and supply of composite material fuel tanks with the integrity of the missile body structure, and realizes modular, economical and reliable production and manufacturing of the product.

[0069] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0070] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for molding a composite fuel tank for missiles, characterized in that, The missile composite fuel tank includes an upper front skin (4), an upper rear skin (2), a lower skin (8), a middle cover plate (3), a front frame (5), and a rear frame (1). The upper front skin (4), the middle cover plate (3), and the upper rear skin (2) are connected sequentially from front to back and are all installed on the upper part of the lower skin (8) to form a compartment structure. The front frame (5) and the rear frame (1) are respectively installed at the front and rear ends of the compartment structure. The middle cover plate (3), the front frame (5) and the rear frame (1) are all used as connection structures with external equipment and are integrally formed by metal material. The upper front skin (4), the upper rear skin (2) and the lower skin (8) are formed by composite material paving. The compartment structure is equipped with multiple partition frames (10). The method includes the following steps: S1: The upper front skin (4), upper rear skin (2), lower skin (8) and reinforcing rib (9) are all prefabricated by carbon fiber layup, and the partition frame (10) is prefabricated by carbon fiber and foam interlayer layup, and then cured by pressurizing and heating in a hot autoclave. S2: Apply body resin to both sides of the partition (10), the inner surface of the upper front skin (4), the inner surface of the upper rear skin (2) and the inner surface of the lower skin (8); S3: The upper front skin (4), upper rear skin (2), lower skin (8), reinforcing rib (9), partition frame (10), front end frame (5), rear end frame (1) and middle cover plate (3) are connected together by adhesive bonding and screwing. The adhesive bonding adopts rich glue extrusion bonding, and the bolts adopt countersunk screws and screwing adopts the form of screw with glue. S4: After the assembly of each sub-compartment is completed, apply excess adhesive to the joints and press it to solidify. Apply sealant to the inside of each sub-compartment to ensure the overall sealing performance. S5: Perform a pressure sealing check on each sub-compartment. If there is any leakage, use adhesive and sealant to reseal the leaking area and then re-inspect. S6: Cover the inspection windows of each sub-compartment with inspection covers (7), and seal the inspection covers (7) by a combination of adhesive bonding and screwing.

2. The molding method for a missile composite fuel tank according to claim 1, characterized in that, The bulkhead (10) divides the entire section into multiple sub-compartments. Among the multiple sub-compartments, the sub-compartment at the front end is provided with a refueling port, and the sub-compartment at the rear end is provided with an exhaust port.

3. The molding method for a missile composite fuel tank according to claim 2, characterized in that, Each of the sub-compartments is provided with a reinforcing rib (9) and an inspection window, and an inspection cover (7) is movably provided on the inspection window. The fuel tank is equipped with a semi-open, semi-sealed embedded part (6) that connects to the outside.

4. The molding method for a missile composite fuel tank according to claim 1, characterized in that, The middle cover plate (3), the front frame (5) and the rear frame (1) are all integrally formed from 7075-T651 aluminum alloy.

5. The molding method for a missile composite fuel tank according to claim 3, characterized in that, The upper front skin (4), upper rear skin (2), lower skin (8) and inspection cover (7) are all made of T300 grade carbon fiber composite material. The reinforcing rib (9) is formed by laying T800 grade carbon fiber composite material; The partition (10) adopts a carbon fiber PMI foam sandwich structure.

6. The molding method for a missile composite fuel tank according to claim 5, characterized in that, The quasi-isotropic ply angle ratio of the upper front skin (4), upper rear skin (2), lower skin (8) and inspection cover (7) is [(0° / 90°) / (±45°)]=1:2; The thickness ratio of carbon fiber to foam in the partition frame (10) is 4:11, and the layup angle ratio of carbon fiber is [(0° / 90°) / (±45°)]=1:

1.

7. The molding method for a missile composite fuel tank according to claim 5, characterized in that, Each carbon fiber structure in the fuel tank adopts a quasi-isotropic layup, and the layup angle is a combination of 0°, ±30°, ±45°, ±60° and 90°.

8. The molding method for a missile composite fuel tank according to claim 3, characterized in that, There are assembly gaps between the structural assembly surfaces of each component in the fuel tank. The assembly surfaces of adjacent components are connected by both adhesive bonding and screw bonding. The adhesive bonding uses rich adhesive filling, and the screw bonding uses countersunk screws with adhesive bonding.

9. The molding method for a missile composite fuel tank according to claim 2, characterized in that, The surfaces of the upper front skin (4), upper rear skin (2), lower skin (8), and partition frame (10) are all coated with body resin.

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