Lightweight composite material underwater pressure-resistant cabin structure and forming method thereof

Abstract

The invention relates to the technical field of preparation of composite material pressure-resistant cabins, in particular to a forming method of a lightweight composite material underwater pressure-resistant cabin, which comprises the following steps: S1, manufacturing a pressure-resistant cabin forming mold; s2, carbon fiber materials are laid on the pressure-resistant cabin forming mold, two symmetrical pressure-resistant cabin shells are sequentially manufactured, and the pressure-resistant cabin shells are integrally formed by the carbon fiber materials; s3, the two sections of pressure-resistant cabin shell bodies obtained after layer laying are placed in an autoclave for hot press forming; s4, the two pressure-resistant cabin shells formed through the autoclave are oppositely bonded; and S5, after the glue joint is completed, spraying a water seal anti-corrosion coating. The invention further relates to a lightweight composite material underwater pressure-resistant cabin structure which comprises a pressure-resistant cabin upper shell and a pressure-resistant cabin lower shell which are symmetrically arranged, and the pressure-resistant cabin upper shell and the pressure-resistant cabin lower shell are glued at the flange edges to form the pressure-resistant cabin. By adopting the mode of combining the layering process and the hot press molding process, the manufacturing method is wide in application range, convenient to install and overhaul and suitable for manufacturing the special-shaped pressure-resistant cabin.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material pressure-resistant cabin preparation, and specifically provides a lightweight composite material underwater pressure-resistant cabin structure and a molding method thereof. Background Art

[0002] At present, as the development and utilization of land space and resources are approaching saturation, various countries have begun to turn their attention to the underwater world of oceans and lakes, such as exploring submarine oil resources, exploring submarine biological resources, etc., and the speed of human development towards the underwater world is getting faster and faster. At present, many unmanned detectors have been developed for underwater resource exploration, and these underwater unmanned equipment require a closed pressure-resistant cabin to install various equipment. The pressure-resistant cabin is a key component for performing underwater surveys, submarine exploration, submarine development and salvage, underwater rescue and other tasks. It can also be used as an underwater operation base for divers. Its design and material selection requirements are extremely strict, and these unmanned detectors not only need to operate underwater, but also need to return to the surface to carry out operations. Therefore, the designed pressure-resistant cabin is required to have the characteristics of light weight, good pressure resistance and water sealing performance.

[0003] As for the development of underwater lightweight pressure-resistant structures, my country's research and application in this area are still in the initial stage. The core issue of underwater pressure-resistant cabin development technology is how to solve a series of development technology problems caused by water pressure and working environment, high and low temperature, high pressure, harsh environment, corrosion, and complex working conditions. In the middle and late part of this century, mankind will enter a new stage of development and utilization of underwater resources. Underwater resources are becoming more and more important to the sustainable development of human economy and society. Under the premise of minimizing the impact on the environment, it is of great significance to vigorously develop new unmanned detection pressure-resistant structure development technology. Therefore, it is particularly important to develop a composite lightweight pressure-resistant cabin to meet normal underwater work.

[0004] Through investigation, it was found that the current water pressure resistant cabins are mainly made of forged steel, aluminum, titanium alloy and other metal materials combined with composite materials, generally prepared by winding process, and the technology is relatively mature. The weight of the pressure cabin made of lightweight materials such as carbon fiber and polymer resin and other lightweight composite materials can be reduced by 40% to 60% compared with the metal cabin of the same specification. This means that at the same weight, more equipment can be working underwater, with a superior performance-price ratio. Since the new lightweight polymer composite material has excellent performance of resistance to high pressure and high temperature, it has more and more wide applications in the fields of navigation, aviation and aerospace.

[0005] Carbon fiber composite materials are widely used in the aerospace field. In recent years, they have gradually begun to be used in underwater equipment, giving full play to their characteristics of light weight, high strength and corrosion resistance. Carbon fiber is a material composed of resin, ceramic, metal, etc. as a matrix and continuous carbon fiber as a reinforcement. It is referred to as carbon fiber composite materials. Parts made of carbon fiber usually adopt a winding or paving molding process. It has low density, high strength, small thermal expansion coefficient, and good corrosion resistance and heat ablation resistance. In the prior art, the following patents involve the design of carbon fiber pressure-resistant cabins: 1. The invention patent application with patent number "202211617582.9" and patent name "Titanium alloy / carbon fiber composite pressure cabin and its manufacturing process" includes a cabin and an end cover, the cabin and the end cover are fixedly connected and enclosed to form a closed receiving space inside, the cabin is formed of titanium alloy / carbon fiber composite material, and part of the end cover extends to the inside of the cabin liner and fits with its inner wall. This solution has high structural strength, small mass and volume.

[0006] 2. The invention patent application with the patent number "202110538494.9" and the patent name "A carbon fiber composite pressure-resistant cabin for underwater robots" includes a cylindrical pressure-resistant cabin, a seal and an end cover. The cylindrical pressure-resistant cabin includes a composite cylinder, an end ring and a waterproof coating. The two end faces of the composite cylinder are bonded with the end rings. The outer surfaces of the composite cylinder and the end rings are provided with a waterproof coating. The end cover is sealed and connected to the cylindrical pressure-resistant cabin through a sealing ring. This solution can achieve axial and radial double-structure sealing with the end covers on both sides, and effectively improve the stress concentration phenomenon at the joint between the end cover and the cabin.

[0007] The carbon fiber pressure-resistant cabin in the above-mentioned prior art is light in weight, and has good pressure resistance and water sealing performance, but they are all processed by metal end covers, which has the problem of heavy metal parts and insufficient lightweight. In addition, the processing technology of winding composite materials on the metal cylindrical shell is used. When it is necessary to manufacture a complex pressure-resistant structure with special-shaped curved surfaces, there is a problem that cannot meet the appearance requirements, and the processing process is cumbersome, and the pressure resistance and sealing performance are limited. Therefore, how to design a composite underwater pressure-resistant cabin structure and its forming method that is light in weight, not easy to leak, easy to install and maintain, easy to form, and suitable for the needs of special-shaped cabins is a problem that needs to be solved urgently. Summary of the invention

[0008] In order to solve the above problems, the present invention provides a lightweight composite underwater pressure-resistant cabin structure and a molding method thereof, which has a wide range of applications, a light structural weight, can improve the convenience of installation and maintenance, can improve production efficiency, and can be suitable for the molding of special-shaped structures.

[0009] The present invention provides a method for forming a lightweight composite underwater pressure-resistant cabin, which specifically comprises the following steps: S1: Making a pressure cabin molding mold; S2: Layering carbon fiber materials on a pressure cabin molding mold to sequentially manufacture two symmetrical pressure cabin shells, the pressure cabin shells being integrally formed of carbon fiber materials; S3: placing the two layers of the pressure cabin shell in an autoclave for hot pressing; S4: bonding the two halves of the pressure cabin shell formed by the autoclave relative to each other to form a finished pressure cabin; S5: After bonding is completed, spray water-tight anti-corrosion coating.

[0010] Furthermore, the layered carbon fiber material in S2 includes multiple carbon fiber groups, each of which needs to lay 3-8 layers of carbon fiber material, the layering angles of adjacent carbon fiber material layers in each carbon fiber group are different, and the carbon fiber material in each carbon fiber group includes fabric prepreg and unidirectional tape prepreg.

[0011] Furthermore, when laying the layers in S2, each group of carbon fiber groups includes 5 carbon fiber material layers, the first and fifth carbon fiber material layers are fabric prepregs, and the second, third and fourth carbon fiber material layers are unidirectional tape prepregs.

[0012] Furthermore, in the 5 carbon fiber material layers of each carbon fiber group during the ply laying in S2, the ply angle of the first layer of fabric prepreg is 0°, the ply angle of the second layer of unidirectional tape prepreg is +45°, the ply angle of the third layer of unidirectional tape prepreg is 0°, the ply angle of the fourth layer of unidirectional tape prepreg is -45°, and the ply angle of the fifth layer of fabric prepreg is 0°.

[0013] Furthermore, during the plying process in S2, after every 3-6 layers of carbon fiber material are laid, a vacuum compaction operation is required to expel the air in the ply; then the next 3-5 layers of carbon fiber material are laid, and then a vacuum compaction operation is performed; and so on, until the plying is completed.

[0014] Furthermore, the pressure cabin forming mold in S1 includes a central cylindrical section and side elliptical sections evenly distributed on both sides of the central cylindrical section; a mold edge is included at the bottom ends of the elliptical section and the cylindrical section toward the outside, and a flange groove connected to the elliptical section and the cylindrical section is opened on the mold edge, and the groove wall of the flange groove is the ply boundary line of the pressure cabin.

[0015] Furthermore, in S2, when laying the layers, a method of alternately combining segmented laying and overall laying is adopted; The segmented laying is to first lay a single cylindrical laying section on the cylindrical section of the pressure cabin forming mold, and then lay a single elliptical laying section on the elliptical section. The laying method of alternating segmented layup with overall layup, i.e., after laying the single-segment elliptical layup section and the single-segment cylindrical layup section on the pressure cabin forming mold, the single-segment cylindrical layup section and the single-segment elliptical layup section are laid as a whole to form an overall layup section; then the next single-segment elliptical layup section and the single-segment cylindrical layup section are laid in sequence on the overall layup section, and then the single-segment elliptical layup section and the single-segment cylindrical layup section are laid as a whole to form the next overall layup section; and so on, the laying is alternately performed until the laying is completed; at the same time, the sealing film needs to be alternately layered between the last 3-5 layers of carbon fiber material layers.

[0016] Furthermore, in S3, when the two-piece pressure-resistant cabin shell with the laminated layers is placed in an autoclave for molding, a pressure of 0.8-1.2 MPa is used in the autoclave, and the shell is heated to 120°C, kept under pressure and kept warm for 1 hour, and then demoulded after being cooled to room temperature.

[0017] Furthermore, when bonding the two halves of the pressure cabin shell relative to each other in S4, J-133 structural adhesive was used, and the thickness of the adhesive layer was 1 mm.

[0018] A lightweight composite underwater pressure-resistant cabin structure is prepared by the above-mentioned lightweight composite underwater pressure-resistant cabin molding method, comprising a symmetrically arranged pressure-resistant cabin upper shell and a pressure-resistant cabin lower shell; the pressure-resistant cabin upper shell and the pressure-resistant cabin lower shell both comprise a cylindrical shell matching the cylindrical section in the pressure-resistant cabin molding mold, an elliptical shell matching the elliptical section, and a flange edge matching the flange groove; the elliptical shell is located at both ends of the cylindrical shell, and the flange edge is circumferentially enclosed by the cylindrical shell and the lower end of the elliptical shell as a whole; the pressure-resistant cabin upper shell and the pressure-resistant cabin lower shell are glued at the flange edges to form a pressure-resistant cabin.

[0019] Compared with the prior art, the present invention can achieve the following beneficial effects: 1. The high modulus carbon fiber prepreg used in this scheme can improve the ability to resist water pressure deformation. Compared with the steel structure metal cabin, the structural weight is reduced by 4 / 5. Under the same weight, the pressure cabin in this scheme can carry more test instruments, which can significantly improve the performance indicators of the submersible.

[0020] 2. This scheme adopts the lamination and autoclave forming process to manufacture the pressure cabin. Compared with the pressure cabin with a winding-molded composite shell and a metal end cover and complicated connection design, this scheme can realize prepreg lamination manufacturing. The autoclave forming process can be applied to the manufacture of cabins of various shapes, not limited to cylindrical pressure cabins.

[0021] 3. This solution adopts a structure divided into upper and lower halves. After opening the upper cabin, various complex underwater equipment can be easily placed in the lower cabin, avoiding the problem that the traditional wrapped pressure cabin structure can only install equipment from the end. For the problem of complex equipment layout and limited installation space, the elliptical end and the cylindrical cabin can enhance the ability to resist water pressure. Under water pressure, the deformation is small, there will be no instability, no leakage, and no permanent deformation. The equipment is fixed in the lower cabin. When installing and repairing the equipment, you only need to open the upper cover, which improves the convenience of installation and maintenance.

[0022] 4. In this scheme, the cross-section design of the upper and lower cabins adopts an integrated cylindrical and elliptical design. The upper shell and the lower shell of the pressure cabin are made of the same material and are an integrated structure. There is no connection interface between two different materials, which improves the connection reliability. The cabin structure adopts a symmetrical two-petal structure design. The two petals are bonded by structural adhesive and can be used in a water depth range of 750 meters. It can not only protect the internal equipment from the external water environment, but also resist the external water pressure and prevent the external environment from corroding the pressure cabin.

[0023] 5. Compared with the traditional structure combining carbon fiber wrapped cabin body and metal end cover, this scheme only needs one mold to realize the manufacture of the whole cabin body, and has the advantages of simple structure, easy molding and high production efficiency. The pressure cabin in the present invention has no connection interface between different materials, avoiding the internal stress of the interface caused by different thermal expansion coefficients of different materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic diagram of the overall structure of a pressure-resistant cabin provided according to an embodiment of the present invention; Figure 2 is an axial cross-sectional schematic diagram provided according to an embodiment of the present invention (the M direction is the axial direction, and the N direction is the radial direction); Figure 3 is a schematic diagram of a ply sequence unit of a carbon fiber group including 5 carbon fiber material layers provided according to an embodiment of the present invention; Figure 4 is a schematic structural diagram of a pressure-resistant cabin forming mold provided according to an embodiment of the present invention; Figure 5 It is a schematic structural diagram of a single cylindrical ply section and a single elliptical ply section during segmented plying provided in an embodiment of the present invention; Figure 6 is a schematic structural diagram of an integral ply section during integral plying provided in an embodiment of the present invention; Figure 7 It is a schematic diagram of the structure in which the upper shell of the pressure cabin and the lower shell of the pressure cabin are glued together at the flange edge according to an embodiment of the present invention; Figure 8is a ply sequence table of a carbon fiber group including 5 carbon fiber material layers provided according to an embodiment of the present invention.

[0025] The reference numerals therein include: cylindrical segment 1, elliptical segment 2, flange edge 3, flange groove 4, ply boundary line 5, single-segment cylindrical ply segment 6, single-segment elliptical ply segment 7, integral ply segment 8, pressure cabin upper shell 9, pressure cabin lower shell 10, cylindrical shell 11, and elliptical shell 12. DETAILED DESCRIPTION

[0026] In the following, reference will be made to the Figure 1-8 Embodiments of the present invention are described. In the following description, the same modules are represented by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, the detailed description thereof will not be repeated.

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the following Figure 1-8 It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0028] A method for forming a lightweight composite underwater pressure-resistant cabin, wherein lightweight means within a water depth of 750 meters, comprises the following steps: S1: Make a pressure-resistant cabin molding mold. Figure 4 As shown, the pressure cabin forming mold includes a central cylindrical section 1 and a side elliptical section 2, the side elliptical sections 2 are evenly distributed on both sides of the central cylindrical section 1, and the bottom ends of the elliptical section 2 and the cylindrical section 1 include a mold edge toward the outside, and a flange groove 4 connected to the elliptical section 2 and the cylindrical section 1 is provided on the mold edge, and the groove wall of the flange groove 4 is the ply boundary line 5 of the pressure cabin. The pressure cabin forming mold is made of P20 steel, and the pressure cabin forming mold is used to manufacture half of the pressure cabin, and one half of the pressure cabin and the other half of the pressure cabin are both manufactured by the pressure cabin forming mold, so only one pressure cabin forming mold is needed to realize the manufacture of the entire pressure cabin.

[0029] S2: Carbon fiber material is laid on a pressure cabin molding mold to sequentially manufacture two symmetrical pressure cabin shells, which are integrally molded from the carbon fiber material.

[0030] The carbon fiber material layering includes multiple carbon fiber groups, each of which needs to lay 3-8 layers of carbon fiber material, and the layering angles of adjacent carbon fiber material layers in each carbon fiber group are different. The carbon fiber material in each carbon fiber group includes fabric prepreg and unidirectional tape prepreg. Figure 3 and Figure 8As shown, in this embodiment, each carbon fiber group includes 5 carbon fiber material layers during laying, the first and fifth carbon fiber material layers are T700 grade carbon fiber fabric prepreg, and the second, third and fourth carbon fiber material layers are M40 grade carbon fiber unidirectional tape prepreg. Figure 3 In the figure, A shows the first layer, B shows the second layer, C shows the third layer, D shows the fourth layer, and E shows the fifth layer. Figure 3 and Figure 8 Ply-1, Ply-2, Ply-3, Ply-4, and Ply-5 respectively represent the first carbon fiber material layer, the second carbon fiber material layer, the third carbon fiber material layer, the fourth carbon fiber material layer, and the fifth carbon fiber material layer in each group of carbon fibers.

[0031] The 0-degree direction of the carbon fiber material layer is defined as the axial direction of the cabin. In each group of 5 carbon fiber material layers, the laying angle of the first layer of fabric prepreg is 0°, the laying angle of the second layer of unidirectional tape prepreg is +45°, the laying angle of the third layer of unidirectional tape prepreg is 0°, the laying angle of the fourth layer of unidirectional tape prepreg is -45°, and the laying angle of the fifth layer of fabric prepreg is 0°.

[0032] During the plying process, after every 3-6 layers of carbon fiber material are laid, a vacuum compaction operation is required to expel the air in the ply to obtain a dense ply structure, and then the next 3-5 layers of carbon fiber material are laid, and then a vacuum compaction operation is performed, and so on, until the plying is completed. In this embodiment, it is preferred to perform a vacuum compaction operation after every 4 layers of carbon fiber material are laid. The above-mentioned plying sequence and plying method can ensure that the composite pressure cabin has various common mechanical properties and has better mechanical properties under water pressure environment.

[0033] At the same time, between the last 3-5 layers of carbon fiber material, a sealing film needs to be alternately laid to effectively fill the pinholes after the carbon fiber prepreg is formed, which can effectively prevent water seepage and leakage in the cabin and improve the sealing performance. In this embodiment, between the last 4 layers of layers, a sealing film is alternately laid.

[0034] In this embodiment, the paving is carried out by alternately combining segmented paving and overall paving. Figure 5 As shown, a single cylindrical ply section 6 is firstly laid on the cylindrical section 1 of the pressure cabin forming mold, and a single elliptical ply section 7 is laid on the elliptical section 2 in sequence.

[0035] The paving method of alternately combining segmented paving and integral paving is to lay the single-segment elliptical paving segment 7 and the single-segment cylindrical paving segment 6 on the pressure cabin forming mold, and then lay the integral paving on the single-segment cylindrical paving segment 6 and the single-segment elliptical paving segment 7 to form a pressure cabin. Figure 6The integral layup section 8 shown in the figure is then laid in sequence on the integral layup section 8 on which the next single-segment elliptical layup section 7 and the single-segment cylindrical layup section 6 are laid, and then the next integral layup section 8 is formed by integrally laying the single-segment elliptical layup section 7 and the single-segment cylindrical layup section 6, and so on, the layers are laid alternately until the layup is completed.

[0036] The purpose of segmented laying is to meet the needs of special-shaped pressure cabins. Separate segmented laying is carried out for different profiles to improve the efficiency of laying. The purpose of overall laying is to tighten and compact the segmented laying sections in the segmented laying. During overall laying, axial laying can be used to tighten the segmented laying sections axially, radial laying can be used to tighten the segmented laying sections longitudinally, and mixed direction laying can be carried out according to actual needs. The structure manufactured in this way has good integrity and good pressure resistance.

[0037] S3: The two halves of the pressure-resistant cabin shell after the layering is placed in the autoclave for hot pressing. When the autoclave is used for molding, the pressure in the autoclave is 0.8-1.2MPa, preferably 1MPa, and the pressure is heated to 120°C, kept at the pressure for 1 hour, and then demoulded after cooling to room temperature.

[0038] S4: The two halves of the pressure-resistant cabin shell formed by the autoclave are bonded together to form a finished pressure-resistant cabin. When the two halves of the pressure-resistant cabin shell are bonded together, J-133 structural adhesive is used, and the adhesive layer thickness is 1mm. J-133 has extremely strong bonding and sealing properties, and has the function of resisting corrosion in seawater environment. The pressure-resistant cabin made by this method has no connection interface between different materials, avoiding the interface internal stress caused by different thermal expansion coefficients of different materials, and has good connection reliability. Structural adhesives such as Figure 7 As shown in S in the middle.

[0039] S5: After the bonding is completed, spray the polyurethane seawater resistant anti-corrosion coating with a thickness of 0.2mm.

[0040] A lightweight composite underwater pressure-resistant cabin structure is prepared by the above-mentioned lightweight composite underwater pressure-resistant cabin molding method, such as Figure 1 , Figure 2 , Figure 7 As shown, it includes a symmetrically arranged pressure cabin upper shell 9 and a pressure cabin lower shell 10. The pressure cabin upper shell 9 and the pressure cabin lower shell 10 both include a cylindrical shell 11 matching the cylindrical segment 1 in the pressure cabin molding mold, an elliptical shell 12 matching the elliptical segment 2 and a flange edge 3 matching the flange groove 4. The elliptical shell 12 is located at both ends of the cylindrical shell 11, and the flange edge 3 is circumferentially enclosed by the lower ends of the cylindrical shell 11 and the elliptical shell 12. The pressure cabin upper shell 9 and the pressure cabin lower shell 10 are glued at the flange edge 3 to form a pressure cabin.

[0041] Regarding the design of the cylindrical shell 11 and the two elliptical shells 12, the cylindrical shell 11 has a good effect of resisting external pressure. The two ends adopt elliptical curved surfaces. When the elliptical shell 12 itself is subjected to external pressure, the structure will produce a large reaction force to balance the influence of water pressure without causing a large deformation. This is exactly the characteristic required by the underwater pressure-resistant cabin. At the same time, the upper shell 9 and the lower shell 10 of the pressure-resistant cabin are divided into upper and lower petals. After the upper shell 9 of the pressure-resistant cabin is opened, various complex underwater equipment can be conveniently placed in the lower shell 10 of the pressure-resistant cabin. The layer boundary line 5 in the pressure-resistant cabin molding mold can better locate the boundary of the flange edge 3 when laying the layers, reducing the post-processing process.

[0042] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. Those skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

[0043] The above specific implementations of the present invention do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for forming a lightweight composite underwater pressure-resistant cabin, characterized in that: The steps include: S1: Making a pressure cabin molding mold; S2: Layering carbon fiber materials on a pressure cabin molding mold to sequentially manufacture two symmetrical pressure cabin shells, the pressure cabin shells being integrally formed of carbon fiber materials; S3: placing the two layers of the pressure cabin shell in an autoclave for hot pressing; S4: bonding the two halves of the pressure cabin shell formed by the autoclave relative to each other; S5: After bonding is completed, spray water-tight anti-corrosion coating.

2. The method for forming a lightweight composite underwater pressure-resistant cabin according to claim 1, characterized in that: The ply carbon fiber material in S2 includes multiple carbon fiber groups, each of which needs to lay 3-8 layers of carbon fiber material, the ply angles of adjacent carbon fiber material layers in each carbon fiber group are different, and the carbon fiber material in each carbon fiber group includes fabric prepreg and unidirectional tape prepreg.

3. The method for forming a lightweight composite underwater pressure-resistant cabin according to claim 2, characterized in that: When laying the layers in S2, each carbon fiber group includes 5 carbon fiber material layers, the first and fifth carbon fiber material layers are fabric prepregs, and the second, third and fourth carbon fiber material layers are unidirectional tape prepregs.

4. The method for forming a lightweight composite underwater pressure-resistant cabin according to claim 3, characterized in that: When laying the layers in S2, among the 5 carbon fiber material layers of each carbon fiber group, the laying angle of the first layer of fabric prepreg is 0°, the laying angle of the second layer of unidirectional tape prepreg is +45°, the laying angle of the third layer of unidirectional tape prepreg is 0°, the laying angle of the fourth layer of unidirectional tape prepreg is -45°, and the laying angle of the fifth layer of fabric prepreg is 0°.

5. The method for forming a lightweight composite underwater pressure-resistant cabin according to claim 4, characterized in that: During the layering process in S2, after every 3-6 layers of carbon fiber material are laid, vacuum compaction operation is required to expel the air in the layer; then the next 3-5 layers of carbon fiber material are laid, and vacuum compaction operation is performed again; and so on, until the layering is completed; at the same time, between the last 3-5 layers of carbon fiber material, sealing film needs to be alternately laid.

6. The method for forming a lightweight composite underwater pressure-resistant cabin according to any one of claims 1 to 5, characterized in that: The pressure-resistant cabin forming mold in S1 comprises a central cylindrical section (1) and side elliptical sections (2) evenly distributed on both sides of the central cylindrical section (1); a mold edge is provided at the bottom ends of the elliptical section (2) and the cylindrical section (1) toward the outside, and a flange groove (4) connected to the elliptical section (2) and the cylindrical section (1) is provided on the mold edge, and the groove wall of the flange groove (4) is a ply boundary line (5) of the pressure-resistant cabin.

7. The method for forming a lightweight composite underwater pressure-resistant cabin according to claim 6, characterized in that: In S2, the laying process is carried out by alternating segmented laying and overall laying; The segmented plying is to first sequentially lay a single cylindrical plying section (6) on the cylindrical section (1) of the pressure cabin forming mold, and then lay a single elliptical plying section (7) on the elliptical section (2); The paving method of alternately combining segmented paving and integral paving is that after laying a single-segment elliptical paving section (7) and a single-segment cylindrical paving section (6) on the pressure cabin forming mold, integral paving is then performed on the single-segment cylindrical paving section (6) and the single-segment elliptical paving section (7) to form an integral paving section (8); then, the next single-segment elliptical paving section (7) and a single-segment cylindrical paving section (6) are sequentially laid on the integral paving section (8); then, the next single-segment elliptical paving section (7) and a single-segment cylindrical paving section (6) are integrally laid on the single-segment elliptical paving section (7) and the single-segment cylindrical paving section (6) to form the next integral paving section (8); and the paving is alternately performed in this way until the paving is completed.

8. The method for forming a lightweight composite underwater pressure-resistant cabin according to claim 7, characterized in that: In S3, the two-piece pressure cabin shell with completed layering is placed in an autoclave for molding. The autoclave is heated to 120°C with a pressure of 0.8-1.2MPa and maintained at the pressure for 1 hour. It can be demoulded after cooling to room temperature.

9. The method for forming a lightweight composite underwater pressure-resistant cabin according to claim 8, characterized in that: When bonding the two halves of the pressure cabin hull in S4, J-133 structural adhesive is used with a thickness of 1 mm.

10. A lightweight composite underwater pressure-resistant cabin structure, prepared by the lightweight composite underwater pressure-resistant cabin molding method described in claim 9, characterized in that: The invention comprises a symmetrically arranged pressure cabin upper shell (9) and a pressure cabin lower shell (10); the pressure cabin upper shell (9) and the pressure cabin lower shell (10) both comprise a cylindrical shell (11) matching the cylindrical section (1) in the pressure cabin forming mold, an elliptical shell (12) matching the elliptical section (2), and a flange edge (3) matching the flange groove (4); the elliptical shell (12) is located at both ends of the cylindrical shell (11), and the flange edge (3) is integrally enclosed around the lower ends of the cylindrical shell (11) and the elliptical shell (12) along the circumferential direction; the pressure cabin upper shell (9) and the pressure cabin lower shell (10) are glued together at the flange edge (3) to form the pressure cabin.

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