A lightweight composite underwater pressure-resistant cabin structure and its forming method

Abstract

The present invention relates to the technical field of composite pressure-resistant cabin preparation, and more specifically, to a method for forming a lightweight composite underwater pressure-resistant cabin, comprising the following steps: S1: preparing a pressure-resistant cabin forming mold; S2: laying carbon fiber material layers on the pressure-resistant cabin forming mold to sequentially form two symmetrical pressure-resistant cabin hulls, wherein the pressure-resistant cabin hulls are integrally formed from the carbon fiber material; S3: placing the two layered pressure-resistant cabin hulls in an autoclave for hot pressing; S4: bonding the two autoclave-formed pressure-resistant cabin hulls relative to each other; and S5: spraying a water-tight anti-corrosion coating after bonding. The present invention also relates to a lightweight composite underwater pressure-resistant cabin structure, comprising a symmetrically arranged pressure-resistant cabin upper hull and a pressure-resistant cabin lower hull, which are bonded together at flange edges to form the pressure-resistant cabin. The present invention utilizes a combination of layering and hot pressing processes, has a wide range of applications, is easy to install and maintain, and is suitable for the production of special-shaped pressure-resistant cabins.

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] As the development and utilization of land-based space and resources approaches saturation, countries are turning their attention to the underwater world of oceans and lakes, exploring for oil and biological resources. Humanity's exploration of the underwater world is accelerating. Numerous unmanned probes have been developed for underwater resource exploration. These underwater drones require a sealed, pressure-resistant hull to house various equipment. These hulls serve as critical components for underwater surveys, seabed exploration, development and salvage, and underwater rescue missions, and also serve as underwater bases for divers. These hulls impose stringent design and material selection requirements. Furthermore, these drones must operate both underwater and on the surface. Therefore, the pressure-resistant hulls must be lightweight, pressure-resistant, and watertight.

[0003] my country's research and application of lightweight underwater pressure-resistant structures is still in its infancy. The core challenge in developing underwater pressure-resistant cabins is addressing a series of technical challenges related to water pressure and the operating environment, including high and low temperatures, high pressure, harsh environments, corrosion, and complex operating conditions. In the mid-to-late 20th century, humanity will enter a new phase in the development and utilization of underwater resources, which are becoming increasingly important to the sustainable development of human economic and social development. While minimizing environmental impact, it is crucial to vigorously develop new unmanned exploration pressure-resistant structure technologies. Therefore, developing a lightweight composite pressure-resistant cabin capable of meeting normal underwater operating requirements is particularly important.

[0004] Through research, it was found that the current water pressure-resistant cabins are mainly made of forged steel and metal materials such as aluminum and titanium alloys combined with composite materials. They are generally prepared using a winding process, and the technology is relatively mature. The pressure-resistant cabins made of lightweight materials such as carbon fiber and light composite materials such as polymer resin can reduce the weight by 40% to 60% compared with metal cabins of the same specifications. 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 materials have excellent properties of resistance to high pressure and high temperature, they are increasingly widely used in fields such as navigation, aviation and aerospace.

[0005] Carbon fiber composites are widely used in the aerospace field and have gradually begun to be used in underwater equipment in recent years, giving full play to their lightweight, high-strength and corrosion-resistant characteristics. 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 are usually formed using a winding or laying process. They have low density, high strength, low thermal expansion coefficient, and good corrosion resistance and thermal ablation resistance. In the existing technology, the following patents involve the design of carbon fiber pressure-resistant cabins:

[0006] 1. Patent number "202211617582.9," entitled "Titanium Alloy / Carbon Fiber Composite Pressure Cabin and Manufacturing Process Thereof," discloses a pressure cabin comprising a cabin body and end covers, which are fixedly connected and enclosed within a sealed containment space. The cabin body is formed of a titanium alloy / carbon fiber composite material, and the end covers extend into the interior of the cabin liner and adhere to its inner wall. This solution offers high structural strength, reduced mass, and volume.

[0007] 2. Patent application number 202110538494.9, entitled "A Carbon Fiber Composite Pressure-Resistant Cabin for Underwater Robots," includes a cylindrical pressure-resistant cabin, seals, and end caps. The cylindrical pressure-resistant cabin comprises a composite cylinder, end rings, and a waterproof coating. The end rings are bonded to the two end faces of the composite cylinder. The outer surfaces of the composite cylinder and end rings are provided with a waterproof coating. The end caps are sealed to the cylindrical pressure-resistant cabin via sealing rings. This solution achieves axial and radial dual-structure sealing with the end caps on both sides and effectively improves stress concentration at the junction of the end caps and the cabin.

[0008] The carbon fiber pressure-resistant cabins mentioned in the prior art are lightweight and offer good pressure resistance and water-tightness. However, they are all manufactured using metal end caps, resulting in heavy metal parts and insufficient lightweighting. Furthermore, the composite material is wrapped around a metal cylindrical shell, making it difficult to meet the required appearance when manufacturing complex pressure-resistant structures with irregular curved surfaces. Furthermore, the manufacturing process is cumbersome, and the pressure resistance and sealing performance are limited. Therefore, designing a lightweight, leak-resistant, easy-to-install and maintain, easy-to-form composite underwater pressure-resistant cabin structure and its forming method, which are suitable for irregular-shaped cabins, are currently urgent issues that need to be addressed. Summary of the Invention

[0009] In order to solve the above problems, the present invention provides a lightweight composite underwater pressure-resistant cabin structure and a forming 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 applied to the forming of special-shaped structures.

[0010] The present invention provides a method for forming a lightweight composite underwater pressure-resistant cabin, which specifically includes the following steps:

[0011] S1: Making the pressure cabin forming mold;

[0012] S2: Layering carbon fiber material on a pressure cabin molding mold to sequentially produce two symmetrical pressure cabin shells. The pressure cabin shell is integrally molded from the carbon fiber material.

[0013] S3: placing the two halves of the pressure cabin shell after the lay-up in an autoclave for hot pressing;

[0014] S4: bonding the two halves of the pressure cabin shell formed in the autoclave relative to each other to form a finished pressure cabin;

[0015] S5: After bonding is completed, spray water-sealed anti-corrosion coating.

[0016] Furthermore, the ply carbon fiber material in S2 includes multiple carbon fiber groups, each carbon fiber group 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.

[0017] Furthermore, 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.

[0018] Furthermore, in the 5 carbon fiber material layers of each carbon fiber group during the laying process in S2, 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°.

[0019] Furthermore, during the laying process in S2, after laying every 3-6 layers of carbon fiber material, a 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 the vacuum compaction operation is performed again; and so on, until the laying is completed.

[0020] 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; the bottom ends of the elliptical section and the cylindrical section include a mold edge 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.

[0021] Furthermore, in S2, when laying the layers, a method of alternating segmented and overall laying is adopted;

[0022] The segmented layup is to first lay a single cylindrical layup section on the cylindrical section of the pressure cabin forming mold, and then lay a single elliptical layup section on the elliptical section.

[0023] The laying method combines segmented laying and integral laying alternately, that is, after laying the single-segment elliptical laying section and the single-segment cylindrical laying section on the pressure cabin forming mold, the single-segment cylindrical laying section and the single-segment elliptical laying section are laid as a whole to form an integral laying section; then the next single-segment elliptical laying section and the single-segment cylindrical laying section are laid in sequence on the integral laying section, and then the single-segment elliptical laying section and the single-segment cylindrical laying section are laid as a whole to form the next integral laying 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 laid between the last 3-5 layers of carbon fiber material.

[0024] 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 cooling to room temperature.

[0025] 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 adhesive layer thickness was 1 mm.

[0026] A lightweight composite underwater pressure-resistant cabin structure is prepared using the above-mentioned lightweight composite underwater pressure-resistant cabin forming method, and includes 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 include a cylindrical shell matching the cylindrical section in the pressure-resistant cabin forming 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; 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.

[0027] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0028] 1. The high-modulus carbon fiber prepreg used in this solution can improve the ability to resist water pressure deformation. Compared with the steel structure metal cabin, the structural weight is reduced by 4 / 5. At the same weight, the pressure-resistant cabin in this solution can carry more test instruments, which can significantly improve the performance indicators of the submersible.

[0029] 2. This solution uses layup and autoclave molding processes to manufacture pressure-resistant cabins. Compared with pressure cabins that are made of composite shells made of wound material and have metal end covers and complicated connection designs, this solution can realize prepreg layup manufacturing. The autoclave molding process can be applied to the manufacture of cabins of various shapes, not limited to cylindrical pressure cabins.

[0030] 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 body 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.

[0031] 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 have 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 influence of the external water environment, but also resist the external water pressure and prevent the external environment from corroding the pressure cabin.

[0032] 5. Compared with the traditional structure combining carbon fiber wrapped cabin body and metal end cover, this solution 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 the different thermal expansion coefficients of different materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a schematic diagram of the overall structure of a pressure cabin provided according to an embodiment of the present invention;

[0034] Figure 2 is an axial cross-sectional view according to an embodiment of the present invention (the M direction is the axial direction, and the N direction is the radial direction);

[0035] Figure 3 2 is a schematic diagram of a ply sequence unit of a carbon fiber group including five carbon fiber material layers provided in an embodiment of the present invention;

[0036] Figure 4 2 is a schematic structural diagram of a pressure-resistant cabin forming mold according to an embodiment of the present invention;

[0037] Figure 5 2. It is a schematic structural diagram of a single cylindrical ply section and a single elliptical ply section during segmented plying according to an embodiment of the present invention;

[0038] Figure 6 is a schematic structural diagram of an integral ply section during integral ply placement according to an embodiment of the present invention;

[0039] Figure 72 is a schematic diagram of a structure in which the upper shell and the lower shell of a pressure cabin are glued together at the flange edge according to an embodiment of the present invention;

[0040] Figure 8 1 is a ply sequence table of a carbon fiber group including 5 carbon fiber material layers provided according to an embodiment of the present invention.

[0041] The reference numerals include: cylindrical section 1, elliptical section 2, flange edge 3, flange groove 4, ply boundary line 5, single-segment cylindrical ply section 6, single-segment elliptical ply section 7, integral ply section 8, pressure cabin upper shell 9, pressure cabin lower shell 10, cylindrical shell 11, and elliptical shell 12. DETAILED DESCRIPTION

[0042] In the following, reference will be made to the Figure 1-8 Describe the embodiment of the present invention. 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, their detailed description will not be repeated.

[0043] In order to make the purpose, technical solutions and advantages of the present invention more clear, the following Figure 1-8 It should be understood that the specific embodiments described herein are only used to illustrate the present invention and do not constitute a limitation of the present invention.

[0044] A method for forming a lightweight composite underwater pressure-resistant cabin, wherein lightweight refers to a cabin capable of being used in water depths of up to 750 meters, comprises the following steps:

[0045] S1: Make the pressure cabin forming mold. Figure 4 As shown, the pressure cabin forming mold includes a central cylindrical section 1 and lateral elliptical sections 2, each located on either side of the central cylindrical section 1. A mold edge extends outward from the bottom ends of the elliptical and cylindrical sections 2 and 1. A flange groove 4 is defined on the mold edge, connecting the elliptical and cylindrical sections 2 and 1. The groove wall of the flange groove 4 forms the pressure cabin's ply boundary line 5. The pressure cabin forming mold is made of P20 steel and is used to manufacture half of the pressure cabin. Both half and the other half of the pressure cabin are manufactured using this mold, so a single mold is required to manufacture the entire pressure cabin.

[0046] S2: Carbon fiber material is laid on the pressure cabin molding mold to sequentially produce two symmetrical pressure cabin shells. The pressure cabin shell is formed in one piece from the carbon fiber material.

[0047] The carbon fiber material layering includes multiple carbon fiber groups, each of which needs to be laid with 3-8 layers of carbon fiber material. The laying 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 8 As shown, in this embodiment, each carbon fiber group includes 5 layers of 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 carbon fiber group.

[0048] 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°.

[0049] During the layup process, after every 3-6 layers of carbon fiber material, vacuum and compaction are performed to expel air from the layers, achieving a dense layer structure. The next 3-5 layers of carbon fiber material are then laid, followed by vacuum and compaction, and so on, until the layup is complete. In this embodiment, vacuum and compaction are preferably performed after every 4 layers of carbon fiber material. This layup sequence and method ensures that the composite pressure cabin possesses all the necessary mechanical properties, with even better mechanical properties in a water pressure environment.

[0050] At the same time, between the last 3-5 carbon fiber material layers, layers of sealant film are alternately applied to effectively fill pinholes in the carbon fiber prepreg after molding, effectively preventing water seepage and leakage in the cabin and improving sealing performance. In this embodiment, layers of sealant film are alternately applied between the last four layers.

[0051] In this embodiment, the laying process is carried out by alternately combining segmented and integral laying. Figure 5 As shown, a single cylindrical ply section 6 is first 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.

[0052] The paving method of alternating segmented and integral paving is to lay the single-segment elliptical paving section 7 and the single-segment cylindrical paving section 6 on the pressure cabin forming mold, and then lay the integral paving on the single-segment cylindrical paving section 6 and the single-segment elliptical paving section 7 to form a Figure 6 The integral layup section 8 is shown in the figure, and then the next single-segment elliptical layup section 7 and the single-segment cylindrical layup section 6 are laid in sequence on the integral layup section 8, and then the next integral layup section 8 is formed by integrally laying on the single-segment elliptical layup section 7 and the single-segment cylindrical layup section 6, and so on, alternating the laying until the laying is completed.

[0053] 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 sections in the segmented laying. During overall laying, the sections can be laid axially to tighten the sections axially, or radially to tighten the sections longitudinally. Mixed direction laying can also be carried out according to actual needs. The structure manufactured in this way has good integrity and good pressure resistance.

[0054] S3: The two layers of the pressure-resistant cabin shell are placed in an autoclave for hot pressing. During the molding process, the autoclave is heated to 120°C, maintained at this pressure for 1 hour, and then cooled to room temperature before demolding.

[0055] S4: Bond the two halves of the pressure-resistant cabin shell after being formed by the autoclave to form a finished pressure-resistant cabin. When bonding the two halves of the pressure-resistant cabin shell, J-133 structural adhesive is used with a thickness of 1mm. J-133 has extremely strong bonding and sealing properties and is resistant to corrosion in seawater environments. The pressure-resistant cabin manufactured by this method has no connection interface between different materials, avoiding the internal stress of the interface caused by the different thermal expansion coefficients of different materials, and has good connection reliability. Structural adhesives such as Figure 7 As shown in the S in the middle.

[0056] S5: After the bonding is completed, spray the polyurethane seawater resistant anti-corrosion coating with a thickness of 0.2mm.

[0057] 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 7As 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 that matches the cylindrical section 1 in the pressure cabin forming mold, an elliptical shell 12 that matches the elliptical section 2, and a flange edge 3 that matches 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.

[0058] The design of the cylindrical shell 11 and the two elliptical shells 12 demonstrates excellent resistance to external pressure. With elliptical curved surfaces at both ends, the elliptical shells 12 themselves, when subjected to external pressure, generate a significant reaction force, balancing the effects of the water pressure without significant deformation. This is precisely the characteristic required for an underwater pressure-resistant cabin. Furthermore, the upper and lower petal-shaped pressure-resistant cabin hull 9 and lower hull 10 allow for the convenient placement of various complex underwater equipment within the lower hull 10 after the upper hull 9 is opened. The layer boundary line 5 within the pressure-resistant cabin mold effectively locates the edge of the flange 3 during layering, reducing post-processing steps.

[0059] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art may make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0060] The above specific embodiments of the present invention do not constitute a limitation on the scope of protection 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 scope of protection 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: manufacturing a pressure-resistant cabin forming mold; the pressure-resistant cabin forming mold in S1 includes 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) serves as a ply boundary line (5) of the pressure-resistant cabin; S2: Layering carbon fiber material on a pressure cabin molding mold to sequentially produce two symmetrical pressure cabin shells. The pressure cabin shell is integrally molded from the carbon fiber material. In S2, the laying process is carried out by alternating segmented and integral 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 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, the 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 the single-segment cylindrical paving section (6) are laid on the integral paving section (8) in sequence, and then the next single-segment elliptical paving section (7) and the single-segment cylindrical paving section (6) are laid on the integral paving section (8); and the alternating paving is repeated until the paving is completed; S3: placing the two halves of the pressure cabin shell after the lay-up 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-sealed 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 out in S2, each carbon fiber group includes 5 layers of 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 in 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 laying process in S2, after laying every 3-6 layers of carbon fiber material, 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 laying is completed; at the same time, sealing film needs to be laid alternately between the last 3-5 layers of carbon fiber material.

6. The method for forming a lightweight composite underwater pressure-resistant cabin according to claim 5, characterized in that: In S3, the two-piece pressure-resistant cabin shell with the laminated layers is placed in an autoclave for molding. The autoclave is heated to 120°C with a pressure of 0.8-1.2 MPa and kept at this temperature for 1 hour. It can be demoulded after cooling to room temperature.

7. The method for forming a lightweight composite underwater pressure-resistant cabin according to claim 6, characterized in that: When bonding the two halves of the pressure cabin shell in S4, J-133 structural adhesive is used with a thickness of 1mm.

8. A lightweight composite underwater pressure-resistant cabin structure, manufactured by the lightweight composite underwater pressure-resistant cabin molding method of claim 7, characterized in that: The invention comprises a symmetrically arranged pressure-resistant cabin upper shell (9) and a pressure-resistant cabin lower shell (10); the pressure-resistant cabin upper shell (9) and the pressure-resistant cabin lower shell (10) both comprise a cylindrical shell (11) matching the cylindrical section (1) in the pressure-resistant 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 entirely surrounded by the lower ends of the cylindrical shell (11) and the elliptical shell (12) along the circumferential direction; the pressure-resistant cabin upper shell (9) and the pressure-resistant cabin lower shell (10) are glued at the flange edge (3) to form the pressure-resistant cabin.

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