A metal-fiber resin sandwich-metal three-layer composite load-bearing shell and a method for manufacturing the same

Abstract

This invention provides a metal-fiber resin sandwich-metal three-layer composite load-bearing shell and its preparation method. The preparation method is as follows: a metal column shell is taken, and its surface is pretreated; prepreg is wound layer by layer on the surface of the metal column shell, with each layer of prepreg laid along the same trajectory and the winding positions completely overlapping, and this winding is repeated n times until the designed thickness is reached; the completed metal column shell is subjected to vacuum heat treatment; after vacuum heat treatment, an outer metal layer is installed on the outermost part of the metal column shell, and adhesive is injected into the cavity between the outer metal layer and the metal column shell, followed by cooling and solidification to obtain the metal-fiber resin sandwich-metal three-layer composite load-bearing shell. The three-layer structure of this invention can synergistically bear loads, significantly improving overall performance, with high structural reliability, long service life, and adaptability to long-term high-load and complex working conditions. It also boasts high production efficiency, low raw material costs, and strong practicality.

Description

Technical Field

[0001] This invention belongs to the field of pressure-bearing structure and shell structure manufacturing technology, specifically relating to a metal-fiber resin sandwich-metal three-layer composite load-bearing shell and its preparation method. Background Technology

[0002] In high-end equipment fields such as deep-sea pressure tanks, aerospace pressure vessels, and underwater vehicle hulls, load-bearing shell structures typically need to simultaneously meet the requirements of lightweight, high load-bearing capacity, and long-term reliability under extreme high-pressure environments. Currently, three main technical solutions are used in engineering: traditional single-layer metal pressure shells, pure fiber composite material shells, and ordinary sandwich structures.

[0003] Traditional single-layer metal pressure shells, such as those made of high-strength steel or titanium alloys, offer good sealing and machinability, but their specific stiffness is relatively low, making them prone to elastic buckling or plastic instability in deep water or high-pressure environments. Furthermore, the high density of metal materials results in an excessively high proportion of structural weight, failing to meet the urgent need for lightweighting in modern equipment. Pure fiber composite shells, such as those made by winding / laying carbon or glass fiber throughout the shell, possess high specific strength and specific stiffness, but their impact resistance is poor. Interlayer or fiber / matrix interfaces are prone to cracking under long-term alternating loads, and their sealing reliability is insufficient, making them unsuitable for long-term use under complex conditions. In addition, traditional fiber composite shells often involve winding fibers throughout the entire shell, which is complex and costly due to the large amount of material used. Ordinary sandwich structures, such as foam cores or honeycomb core composite panel structures, achieve weight reduction to some extent, but under high hydrostatic pressure, the core layer is prone to shear instability or crushing. The limited bonding strength between the panel and the core layer can easily lead to debonding, resulting in localized crushing or even overall failure. In addition, existing technologies are mostly simple adhesive composites, with weak mechanical synergy between materials, and the molding process is not matched with the structural stress characteristics, making it difficult to simultaneously take into account load-bearing capacity and structural stability.

[0004] Therefore, how to provide a composite load-bearing shell structure and supporting processing technology that can simultaneously meet the requirements of high load-bearing capacity, lightweight, and high stability has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] This invention addresses the problems existing in the prior art by providing a metal-fiber resin sandwich-metal three-layer composite load-bearing shell and its preparation method.

[0006] The present invention adopts the following technical solution: (I) This invention provides a method for preparing a metal-fiber resin sandwich-metal three-layer composite load-bearing shell, comprising the following steps: S1. Take the metal cylinder shell and pre-treat the surface of the metal cylinder shell; S2. Wrap prepreg layer by layer around the surface of the metal column shell. Each layer of prepreg is laid along the same trajectory and the winding positions completely overlap. Repeat the winding process n times until the designed thickness is achieved. S3. Vacuum heat treatment is performed on the completed metal column shell; S4. After vacuum heat treatment, an outer metal layer is installed on the outermost part of the metal column shell. Adhesive is injected into the cavity between the outer metal layer and the metal column shell, and the mixture is cooled and solidified to obtain a metal-fiber resin sandwich-metal three-layer composite load-bearing shell.

[0007] Furthermore, in step S1, the pretreatment method is as follows: the surface of the metal column shell is sandblasted to roughen the surface, and then the roughened surface of the metal column shell is cleaned.

[0008] Furthermore, in step S2, before wrapping the prepreg, protective tape is first pasted 25mm from both ends of the metal column shell.

[0009] Furthermore, in step S2, each layer of prepreg is laid using the same spiral trajectory, and the pitch of the spiral trajectory is 40~60 mm.

[0010] Furthermore, in step S3, the vacuum heat treatment specifically involves: placing the completed metal column shell into a vacuum bag, with an air extraction port on the surface of the vacuum bag, drawing a vacuum through the air extraction port, and then placing it into a heating device for heating.

[0011] Furthermore, the heating temperature is 200~300℃, and the heating time is 20~40min.

[0012] Furthermore, in step S4, the glue injection operation is as follows: take two flange plates and fix them to both ends of the metal column shell assembly respectively. Each of the two flange plates has a glue injection hole. Glue is injected through the glue injection hole of one flange plate. The glue flows along the cavity between the outer metal layer and the metal column shell. When the glue flows out from the glue injection hole of the other flange plate, the glue injection is completed. The glue injection holes of the two flange plates are then sealed. After the glue cools and solidifies, the flange plates are removed.

[0013] Furthermore, the two flange plates are fixed by a number of screws; each of the two flange plates has a number of through holes that match the number of screws, and the positions of the through holes on the two flange plates correspond; both ends of the screws pass through the through holes of the two flange plates and are fixedly connected to nuts.

[0014] Furthermore, the screw and flange plate have four through holes, which are evenly distributed along the circumference of the flange plate.

[0015] (ii) The present invention also provides a metal-fiber resin sandwich-metal three-layer composite load-bearing shell, including a metal column shell, a prepreg layer and an outer metal layer; the prepreg layer is laid on the surface of the metal column shell, and the prepreg layer does not cover the entire surface of the metal column shell; the outer metal layer is sleeved on the metal column shell on which the prepreg is laid, and the inner surface of the outer metal layer is in contact with the outer surface of the prepreg layer; there is a cavity between the outer metal layer and the surface of the metal column shell where the prepreg is not laid, and the cavity is filled with adhesive.

[0016] Furthermore, the prepreg layer is spirally distributed on the surface of the metal column shell with a pitch of 40-60 mm; the thickness of the prepreg layer is 10-20 mm.

[0017] The beneficial effects of this invention are: (1) The composite bearing shell of the present invention has a three-layer structure of metal-fiber resin sandwich-metal, which can work together to bear the load. The metal layer provides strong interface protection and sealing support, and the prepreg layer provides high specific stiffness and buckling resistance. It effectively solves the problems of large weight and easy instability of single-layer metal shells, as well as poor impact resistance and insufficient sealing of simple composite material shells, and the overall performance is greatly improved.

[0018] (2) The present invention adopts a dual interface strengthening method of chemical bonding and mechanical fixation, combined with the edge metal encapsulation structure, which significantly reduces the risk of delamination between the core layer and the metal shell. The structure has high reliability, long service life, and can be adapted to long-term high load and complex working conditions.

[0019] (3) The process of this invention is stable, simple to operate, and can be mass-produced. It is suitable for manufacturing large-size, complex curved surface bearing shells, with high production efficiency and low raw material cost, and has strong practicality.

[0020] (4) The metal-fiber resin sandwich-metal three-layer composite bearing shell of the present invention has multiple advantages such as lightweight, high pressure resistance, impact resistance, reliable sealing and environmental corrosion resistance. It has a wide range of applications and can be widely used in high-end scenarios such as deep sea, high pressure, aviation and heavy-duty equipment, with high application value. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the metal cylindrical shell structure of the present invention; Figure 2 This is a schematic diagram of the metal column shell of the present invention after prepreg has been laid; Figure 3 This is a distribution diagram of the flange plates used for adhesive injection in this invention; Figure 4 This is a schematic diagram of the connection between the flange plate and the screw rod of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1 This invention provides a method for preparing a metal-fiber resin sandwich-metal three-layer composite load-bearing shell, comprising the following steps: Step S1, Preprocessing: Take a metal cylindrical shell with a length of 1350mm ( Figure 1 The process involves removing oil, scale, and other impurities from the metal surface, followed by sandblasting to roughen the surface and improve interfacial bonding strength, thereby enhancing the interfacial bond between the composite material and the metal. Subsequently, compressed air or a lint-free cloth is used to thoroughly remove sand particles and dust from the roughened metal shell surface to prevent impurities from affecting the bonding. Finally, a rotation axis baseline is marked on the metal shell surface to provide a reference for subsequent control of layup angles and lengths.

[0024] Step S2, Laying the prepreg: First, apply protective tape 25mm from both ends of the metal column shell to define the area where the prepreg is laid, preventing resin from overflowing and contaminating the ends.

[0025] Subsequently, prepreg (FRP) is wound layer by layer onto the surface of the metal column shell, with each layer of prepreg laid using the same helical trajectory (pitch of 50 mm). Figure 2 The prepreg layers are laid in a 50mm wide, overlapping pattern, with each layer repeated n times until the designed thickness of 20mm is achieved. Each layer is rolled with a roller to remove air bubbles and wrinkles, ensuring a tight bond between the prepreg and the metal, as well as between adjacent prepreg layers. Care should be taken to stagger the overlaps between adjacent prepreg layers to avoid concentrated overlaps that could affect structural strength.

[0026] Step S3, Vacuum heat treatment: The completed metal column shell is placed into a vacuum bag and then into an autoclave. The vacuum bag has an extraction port on its surface, which is connected to a vacuum pump via a pipe. The vacuum pump is turned on to create a vacuum. Once a vacuum level of -0.095 to -0.1 MPa is reached, the valve is closed, and the material is heat-treated at 200°C for 30 minutes.

[0027] Step S4, Injecting Adhesive: After vacuum heat treatment, an outer metal layer (titanium film) is installed on the outermost surface of the metal column shell. Then, aviation adhesive is injected into the cavity between the outer metal layer and the metal column shell. The adhesive injection process is as follows: like Figures 3-4 Two flange plates are placed at both ends of the metal column shell assembly (prepreg-metal column shell-titanium membrane). Each flange plate has four circumferentially evenly distributed through holes, and the through holes on the two flange plates are positioned correspondingly. Four screws are taken, and their ends are passed through the through holes of the two flange plates and fixed with nuts, thereby fixing the two flange plates to both sides of the metal column shell assembly. Adhesive is injected through the injection hole of one flange plate. The adhesive flows along the spiral cavity between the titanium membrane and the metal column shell. When the adhesive flows out from the injection hole of the other flange plate, the adhesive injection is complete. Then, the injection holes of the two flange plates are sealed with caps. After the adhesive cools and solidifies, the flange plates and screws are removed, resulting in a metal-fiber resin sandwich-metal three-layer composite load-bearing shell.

[0028] Example 2 This embodiment provides a metal-fiber resin sandwich-metal three-layer composite load-bearing shell, which is prepared by the method described in Example 1 and includes a metal column shell, a prepreg layer and an outer metal layer (titanium film).

[0029] like Figure 2 As shown, the prepreg layer is laid on the surface of the metal column shell, but the prepreg layer does not cover the entire surface of the metal column shell. Specifically, the prepreg layer is distributed in a spiral pattern on the surface of the metal column shell, with a pitch of 50 mm and a thickness of 20 mm.

[0030] The outer metal layer is fitted over the prepreg-covered metal column shell, and the inner surface of the outer metal layer is in contact with the outer surface of the prepreg layer. There are cavities on the surfaces of the outer metal layer and the metal column shell where the prepreg is not laid, and these cavities are filled with aviation adhesive.

[0031] Comparative Example 1 Comparative Example 1 provides a three-layer composite load-bearing shell, the preparation method of which includes the following steps: Step S1, Preprocessing: A 1350mm long metal column shell was taken, and impurities such as oil and oxide scale on the metal surface were removed. The surface of the metal column shell was sandblasted to roughen it and improve the interfacial bonding strength, thereby improving the interfacial bonding force between the composite material and the metal. Then, the sand particles and dust on the roughened surface of the metal column shell were thoroughly removed with compressed air or a lint-free cloth to avoid impurities affecting the bonding. Finally, the rotation axis baseline was marked on the surface of the metal column shell to provide a reference for subsequent control of the layup angle and length.

[0032] Step S2, Laying the prepreg: First, apply protective tape 25mm from both ends of the metal column shell to define the area where the prepreg is laid, preventing resin overflow and contamination of the ends. Then, wrap the prepreg (FRP) layer by layer around the surface of the metal column shell, covering the entire surface with a thickness of 20mm. Roll each layer with a roller to remove air bubbles and wrinkles, ensuring a tight bond between the prepreg and the metal, as well as between adjacent prepreg layers.

[0033] Step S3, Vacuum heat treatment: The completed metal column shell is placed into a vacuum bag and then into an autoclave. The vacuum bag has an extraction port on its surface, which is connected to a vacuum pump via a pipe. The vacuum pump is turned on to create a vacuum. Once a vacuum level of -0.095 to -0.1 MPa is reached, the valve is closed, and the material is heat-treated at 200°C for 30 minutes.

[0034] Step S4: Install the outer metal layer: After vacuum heat treatment, an outer metal layer (titanium film) is installed on the outermost part of the metal column shell, and the inner surface of the outer metal layer is bonded to the outer surface of the prepreg layer.

[0035] The composite load-bearing shells prepared in Comparative Example 1 and Example 1 were compared in performance, with measurements taken on pressure resistance, buckling load, weight, interfacial bond strength, and long-term fatigue stability. Test results show that, compared to Comparative Example 1, the composite load-bearing shell prepared by the method in Example 1 of this invention exhibits 25%–35% improved pressure resistance and buckling resistance under the same weight conditions, is less prone to interfacial delamination, and demonstrates superior long-term service stability; simultaneously, it requires less prepreg, resulting in lower preparation costs.

[0036] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a metal-fiber resin sandwich-metal three-layer composite load-bearing shell, characterized in that, Includes the following steps: S1. Take the metal cylinder shell and pre-treat the surface of the metal cylinder shell; S2. Wrap prepreg layer by layer around the surface of the metal column shell. Each layer of prepreg is laid along the same trajectory and the winding positions completely overlap. Repeat the winding process n times until the designed thickness is achieved. S3. Vacuum heat treatment is performed on the completed metal column shell; S4. After vacuum heat treatment, an outer metal layer is installed on the outermost part of the metal column shell. Adhesive is injected into the cavity between the outer metal layer and the metal column shell, and the mixture is cooled and solidified to obtain a metal-fiber resin sandwich-metal three-layer composite load-bearing shell.

2. The method for preparing the metal-fiber resin sandwich-metal three-layer composite load-bearing shell according to claim 1, characterized in that, In step S1, the pretreatment method is as follows: the surface of the metal column shell is sandblasted to roughen the surface, and then the roughened surface of the metal column shell is cleaned.

3. The method for preparing the metal-fiber resin sandwich-metal three-layer composite load-bearing shell according to claim 1, characterized in that, In step S2, before wrapping the prepreg, protective tape is first pasted on both ends of the metal column shell.

4. The method for preparing the metal-fiber resin sandwich-metal three-layer composite load-bearing shell according to claim 1, characterized in that, In step S2, each layer of prepreg is laid using the same spiral trajectory, and the pitch of the spiral trajectory is 40~60 mm.

5. The method for preparing the metal-fiber resin sandwich-metal three-layer composite load-bearing shell according to claim 1, characterized in that, In step S3, the vacuum heat treatment specifically includes: The completed metal column shell is placed into a vacuum bag. The vacuum bag has an air extraction port on its surface. A vacuum is drawn through the air extraction port, and then the shell is heated by a heating device.

6. The method for preparing the metal-fiber resin sandwich-metal three-layer composite load-bearing shell according to claim 5, characterized in that, The heating temperature is 200~300℃, and the heating time is 20~40min.

7. The method for preparing the metal-fiber resin sandwich-metal three-layer composite load-bearing shell according to claim 1, characterized in that, In step S4, the glue injection operation is as follows: Take two flange plates and fix them to both ends of the metal column shell assembly. Each flange plate has an injection hole. Inject the adhesive through the injection hole of one flange plate. The adhesive flows along the cavity between the outer metal layer and the metal column shell. When the adhesive flows out from the injection hole of the other flange plate, the injection is complete. Seal the injection holes of both flange plates. After the adhesive cools and solidifies, remove the flange plates.

8. The method for preparing the metal-fiber resin sandwich-metal three-layer composite load-bearing shell according to claim 7, characterized in that, The two flange plates are fixed by a number of screws; The two flange plates are each provided with the same number of through holes as the screws, and the positions of the through holes on the two flange plates are corresponding; the two ends of the screws pass through the through holes of the two flange plates respectively and are fixedly connected with nuts.

9. A metal-fiber resin sandwich-metal three-layer composite load-bearing shell, characterized in that, Includes a metal shell, a prepreg layer, and an outer metal layer; The prepreg layer is laid on the surface of the metal column shell, but the prepreg layer does not cover the entire surface of the metal column shell; the outer metal layer is fitted over the metal column shell on which the prepreg is laid, and the inner surface of the outer metal layer is in contact with the outer surface of the prepreg layer. There is a cavity between the outer metal layer and the surface of the metal column shell where the prepreg is not laid, and the cavity is filled with adhesive.

10. The metal-fiber resin sandwich-metal three-layer composite load-bearing shell according to claim 9, characterized in that, The prepreg layer is spirally distributed on the surface of the metal column shell, with a pitch of 40~60 mm; The thickness of the prepreg layer is 10~20 mm.

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