Pre-embedded metal composite pressure vessel and its preparation method and forming die

Abstract

The present application relates to the technical field of composite material forming process, and particularly relates to a composite pressure vessel with embedded metal parts and a preparation method and a forming die thereof. The preparation method comprises the following steps: making a forming die, preparing a prepreg, laying the prepreg to form a sealing reinforcing layer, vacuum bag heating and pressurizing curing, polishing the sealing reinforcing layer, preparing a rubber-embedded metal part-rubber composite layer, installing the rubber-embedded metal part-rubber composite layer, laying a skin and an end frame, demolding after pressurizing and curing to obtain the composite pressure vessel with embedded metal parts. The preparation method provided by the present application can realize the assembly of metal parts without machining openings on the composite pressure vessel, and can avoid the problems of poor process reliability and defects of interfacial debonding between the large-size embedded metal parts and the composite material due to the mismatch of thermal expansion coefficients after the curing of the composite material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite material forming process, in particular to a composite pressure vessel with embedded metal parts and a preparation method and forming die thereof. BACKGROUND

[0002] In recent years, with the rapid development of aerospace technology and national defense industry, the demand for higher performance aerospace equipment has given birth to a large number of new materials and advanced manufacturing processes. Among them, carbon fiber reinforced high performance resin matrix composite material has the advantages of high specific strength, high specific modulus and strong designability, and is widely used in high-tech fields such as weapon equipment and spacecraft, and gradually replaces metal materials.

[0003] The composite pressure vessel is a common composite structure, which usually needs to meet the requirements of sealing and bearing internal pressure. Such use requirements seriously limit the interface design and assembly process of the composite pressure vessel.

[0004] In the prior art, in order to set the interface and assemble the connection work on the side wall of the container, there are usually two process methods. The first method needs to open the side wall of the container and install metal parts on the inside of the container. However, this process method needs to damage the shell structure, affects the integrity of the composite material, and thus reduces the bearing performance. In addition, sealing measures need to be taken at the opening installation position, which increases the sealing risk. The second method is to pre-embed metal parts in the composite pressure vessel during the forming process, which can reduce the assembly work. This scheme effectively avoids the shortcomings of the first method, but introduces new problems. The mismatch of thermal expansion coefficients between the metal parts and the composite parts usually causes a large stress between them after solidification and cooling, and there is a risk of debonding at the interface between the metal parts and the composite parts.

[0005] Based on the above technical background, it is urgent to solve the problem of debonding between the composite pressure vessel and the embedded metal parts. In engineering, the structure of the metal part is usually optimized, and grooves are set on the surface of the metal part to make the composite material and the metal part engage together to coordinate the deformation difference caused by the different thermal expansion coefficients. However, this method increases the difficulty of process implementation and design. Secondly, the method of increasing the adhesive film at the interface between the composite material and the metal part is usually used to coordinate the thermal expansion deformation mismatch. This method also has limitations. The adhesive film has limited coordination ability and cannot solve the problem of deformation mismatch between large-size embedded metal parts and composite materials. In addition, the adhesive film needs to consider the adhesion strength with the composite material and the metal part and its own toughness, which increases the difficulty of material selection and the reliability of the process. SUMMARY

[0006] The present application aims to overcome the defects of the prior art, and provides a pre-embedded metal piece composite pressure vessel, a preparation method thereof and a forming die, which can realize the assembly of metal pieces without machining openings on the composite pressure vessel, and avoid the defects of debonding of the interface between the two materials due to the mismatch of thermal expansion coefficients of the large-size pre-embedded metal piece and the composite material after the curing of the composite material, and the problem of poor process reliability.

[0007] To achieve the above-mentioned object, the present application adopts the following specific technical solutions:

[0008] The present application provides a forming die for a pre-embedded metal piece composite pressure vessel, which is a hollow cylindrical split structure, and comprises a first recessed surface, a second recessed surface, a skin laying surface and an end surface. The end surface is two bottom surfaces of the hollow cylinder, which are used to form an end frame. The skin laying surface is the outer surface of the hollow cylinder, which is used to form a skin. The middle part of the skin laying surface forms the second recessed surface around the hollow cylindrical axis, which is used to form a sealing and reinforcing layer. The first recessed surface is arranged at the middle position of the second recessed surface, which is used to install the pre-embedded metal piece.

[0009] Preferably, the forming die is divided into four parts along the circumference, and a demolding angle greater than 0 degrees is arranged between each part. The forming die is divided into two parts along the axis, so as to facilitate the demolding of the product.

[0010] The present application provides a preparation method for a pre-embedded metal piece composite pressure vessel, which comprises the following steps:

[0011] S1, preparing the above-mentioned forming device;

[0012] S2, preparing a prepreg containing a matrix material and a reinforcing material;

[0013] S3, laying the prepreg on the first recessed surface and the second recessed surface to form a sealing and reinforcing layer;

[0014] S4, using a vacuum bag to vacuum package the forming die after laying the sealing and reinforcing layer, and placing it into a hot press tank for heating, pressurizing and curing;

[0015] S5, removing the vacuum bag and polishing the sealing and reinforcing layer to make the surface rough, and making the sealing and reinforcing layer laid on the second recessed surface flush with the skin laying surface;

[0016] S6, preparing a rubber-pre-embedded metal piece-rubber composite layer;

[0017] S7, determining the installation position of the rubber-pre-embedded metal piece-rubber composite layer relative to the sealing and reinforcing layer, brushing the matrix material on the two side surfaces of the rubber-pre-embedded metal piece-rubber composite layer, and installing the rubber-pre-embedded metal piece-rubber composite layer on the surface of the sealing and reinforcing layer on the first recessed surface.

[0018] S8, using the prepreg to lay up on the surface of the skin laying plane, the sealing reinforcement layer and the rubber-pre-embedded metal part-rubber composite layer to form the skin, and using the prepreg to lay up on the end surface to form the end frame;

[0019] S9, placing the forming mold after the prepreg laying in step S8 into a hot press tank for pressure curing, and demolding after the curing to obtain the pre-embedded metal part composite material pressure vessel.

[0020] Preferably, in step S2, the base material is selected as bismaleimide resin, the reinforcing material is selected as T700 continuous carbon fiber, and the prepreg is prepared by hot melt prepreg method, and the fiber volume content of the prepreg is 54% to 60%.

[0021] Preferably, in step S6, the preparation of the rubber-pre-embedded metal part-rubber composite layer comprises the following steps:

[0022] S61, performing sand blasting treatment on the surface of the pre-embedded metal part;

[0023] S62, performing polishing on the surface of the rubber;

[0024] S63, cleaning the pre-embedded metal part after the sand blasting treatment and the rubber after the polishing;

[0025] S64, brushing structural adhesive resistant to resin curing temperature on both side surfaces of the pre-embedded metal part, bonding the rubber on the surface of the pre-embedded metal part and laying up flat;

[0026] S65, performing heating and curing treatment on the structural adhesive to obtain the rubber-pre-embedded metal part-rubber composite layer.

[0027] Preferably, the rubber is selected as high-temperature-resistant silicone rubber, and the pre-embedded metal part is made of 30CrMnSi material.

[0028] The application provides a pre-embedded metal part composite material pressure vessel prepared by the preparation method.

[0029] The application can achieve the following technical effects:

[0030] 1. The preparation method of the pre-embedded metal part composite material pressure vessel can realize the assembly of the metal part without machining opening of the composite material pressure vessel, and can avoid the problems of poor process reliability and defects of interface debonding of the two materials due to the mismatch of thermal expansion coefficients of the large-size pre-embedded metal part and the composite material after the curing of the composite material.

[0031] 2. By selecting a high-temperature-resistant structural adhesive, rubber that matches the curing temperature of the resin matrix of the composite material, a "rubber-embedded metal part-rubber" composite layer is prepared separately, and the composite layer is embedded into the composite material as a complete embedded part, thereby improving the process stability of the composite layer;

[0032] 3. The structural adhesive layer between the rubber and the metal part can ensure the connection strength of the metal part and the rubber; the high-performance resin co-curing layer between the rubber and the composite material, which is the same as the matrix of the composite material, can ensure the connection strength of the composite material and the rubber; the introduction of the composite layer process not only ensures the connection strength of the embedded part, but also solves the problem of interface debonding between the large-size embedded metal part and the composite material due to the mismatch of the thermal expansion coefficients. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a structural schematic diagram of a forming mold of a pre-embedded metal part composite material pressure vessel according to an embodiment of the present application.

[0034] Figure 2 is a flowchart of a preparation method of a pre-embedded metal part composite material pressure vessel according to an embodiment of the present application.

[0035] Figure 3 is a structural schematic diagram of a rubber-embedded metal part-rubber composite layer according to an embodiment of the present application.

[0036] Figure 4 is a sectional view of a rubber-embedded metal part-rubber composite layer according to an embodiment of the present application.

[0037] Figure 5 is a structural schematic diagram of a sealing and reinforcing layer surface of a rubber-embedded metal part-rubber composite layer installed on a first recessed surface according to an embodiment of the present application.

[0038] Figure 6 is a structural schematic diagram of a pre-embedded metal part composite material pressure vessel according to an embodiment of the present application.

[0039] Figure 7 is a sectional view of a pre-embedded metal part composite material pressure vessel according to an embodiment of the present application.

[0040] Figure 8 is a sectional view of a pre-embedded metal part composite material pressure vessel according to an embodiment of the present application.

[0041] The reference signs in the drawings include:

[0042] The first recessed surface 1, the second recessed surface 2, the skin laying surface 3, the end surface 4, the embedded metal part 5, the rubber layer 6, the embedded metal part interface 7, the skin 8, and the end frame 9. DETAILED DESCRIPTION

[0043] Hereinafter, embodiments of the present application will be described with reference to the accompanying drawings. In the following description, the same modules are denoted by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated.

[0044] In order to make the objectives, technical solutions, and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not constitute a limitation on the present application.

[0045] The embodiment of the present application provides a forming die of a pre-embedded metal piece composite material pressure vessel, Figure 1 The structure of the forming die is shown as follows, Figure 1 As shown in the figure, the forming die is a hollow cylindrical split structure, and the forming die comprises a first recessed surface 1, a second recessed surface 2, a skin laying surface 3, and an end surface 4. The end surface 4 is two bottom surfaces of the hollow cylinder, which is used to form the end frame of the pressure vessel. The skin laying surface 3 is the outer side surface of the hollow cylinder, which is used to form the skin of the pressure vessel. The second recessed surface 2 is formed in the middle of the skin laying surface 3 around the hollow cylindrical axis, which is used to form the sealing reinforcing layer of the pressure vessel. The first recessed surface 1 is arranged at the middle position of the second recessed surface 2, which is used to install the pre-embedded metal piece.

[0046] The embodiment of the present application provides a preparation method of a pre-embedded metal piece composite material pressure vessel, Figure 2 The flow of the preparation method is shown as follows, Figure 2 As shown in the figure, the preparation method comprises the following steps:

[0047] S1, manufacturing the forming die described above.

[0048] S2, preparing a prepreg containing a matrix material and a reinforcing material.

[0049] The reinforcing material is T700 continuous carbon fiber, the resin matrix selects high-temperature-resistant bismaleimide resin, and the prepreg with a fiber volume content of 57% is prepared by using hot melt prepreg method, and the prepreg tape width is 300mm.

[0050] S3, laying the prepreg on the first recessed surface 1 and the second recessed surface 2 of the forming die to form a sealing reinforcing layer.

[0051] The circumferential laying proportion of the sealing reinforcing layer is 40%, and the sealing reinforcing layer is 2mm equal-thickness laying.

[0052] S4, using a vacuum bag to vacuum package the forming die after laying the sealing reinforcing layer, and putting it into a hot press tank for heating, pressurizing and curing.

[0053] The curing pressure is 0.2 MPa, and there are two temperature steps in the curing process, which are 130 DEG C and 180 DEG C.

[0054] S5, the vacuum bag is removed, and the sealing reinforcing layer is polished to make the surface of the sealing reinforcing layer rough and the sealing reinforcing layer laid on the second concave surface 2 flush with the skin laying surface 3.

[0055] The skin laying surface 3 of the forming mold needs to be protected before polishing to prevent damage to the skin laying surface 3 during polishing.

[0056] S6, a rubber-embedded metal part-rubber composite layer is prepared.

[0057] S61, 16# emery is used to sand blast the surface of the embedded metal part 5;

[0058] S62, 400# sandpaper is used to slightly polish the front and back surfaces of the rubber layer 6;

[0059] S63, ethyl acetate is used to clean the surfaces of the embedded metal part 5 and the rubber layer 6;

[0060] S64, structural adhesive resistant to resin curing temperature is brushed on both sides of the surface of the embedded metal part 5, the thickness of the adhesive is controlled to be 0.1 mm, the rubber is adhered to both sides of the surface of the embedded metal part 5 and is laid flat.

[0061] S65, the structural adhesive is heated and cured to prepare a rubber-embedded metal part-rubber composite layer.

[0062] Figure 3 The structure of the rubber-embedded metal part-rubber composite layer prepared by the embodiment of the application is shown, Figure 4 The cross-sectional structure of the rubber-embedded metal part-rubber composite layer is shown, the metal embedded part 5 comprises a metal embedded part interface 7, the metal embedded part 5 is made of 30CrMnSi material, and the rubber material is high-temperature-resistant silicone rubber.

[0063] S7, the installation position of the rubber-embedded metal part-rubber composite layer relative to the sealing reinforcing layer is determined, the base material is brushed on both sides of the surface of the rubber-embedded metal part-rubber composite layer, and the rubber-embedded metal part-rubber composite layer is installed on the surface of the sealing reinforcing layer on the first concave surface 1.

[0064] The rubber-embedded metal part-rubber composite layer is tried to be installed into the sealing reinforcing layer laid on the first concave surface 1, the distance between the metal embedded part interface 7 and the end surface 4 of the forming mold is positioned and detected to ensure the relative position accuracy of the metal embedded part relative to the entire composite material pressure container, Figure 5 The structure of the rubber-embedded metal part-rubber composite layer installed on the surface of the sealing reinforcing layer on the first concave surface is shown.

[0065] S8. Prepreg is laid on the surface of the skin laying surface 3, the sealing reinforcement layer and the rubber-embedded metal-rubber composite layer to form the skin 8. Prepreg is laid on the end face 4 to form the end frame 9.

[0066] Specifically, the sealing reinforcement layer is 2mm thick and 300mm wide; the rubber-embedded metal-rubber composite layer is 200mm high, 200mm long, and 0.5mm thick; the skin is 3mm thick, the end frame is 8mm thick, the total height of the pressure vessel is 800mm, the outer diameter is 500mm, and the wall thickness of the embedded metal parts is 3mm. The 3mm skin extends to the end frame to ensure fiber continuity, and the remaining 5mm of the end frame layer is laid separately on the continuous layer surface.

[0067] S9. Place the mold after laying the prepreg into a hot autoclave for pressure curing. After curing, demold to obtain a pressure vessel with embedded metal parts composite material.

[0068] The curing temperature steps are 130℃, 180℃, and 240℃, and the curing pressure is 0.3 MPa.

[0069] This invention provides a pressure vessel made of composite material with embedded metal parts, prepared by the above-described method. Figure 6 The structure of a composite pressure vessel with embedded metal parts is shown. Figure 7 , Figure 8 The cross-sectional structure of a composite pressure vessel with embedded metal parts is shown.

[0070] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0071] Although 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 can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

[0072] The above detailed description of the application is not intended to limit the scope of the application. Various other changes and modifications of the application will be apparent to those skilled in the art and such changes and modifications are intended to be included within the scope of the application as defined by the following claims.

Claims

1. A method for preparing a pressure vessel with embedded metal components, characterized in that, Includes the following steps: S1. Making molding molds; S2. Prepare a prepreg containing a matrix material and a reinforcing material; S3. The prepreg is laid on the first and second recessed surfaces of the molding die to form a sealing reinforcement layer; S4. Vacuum seal the mold after the sealing reinforcement layer has been laid using a vacuum bag, and then place it in an autoclave for heating and pressure curing. S5. Remove the vacuum bag and polish the sealing reinforcement layer to roughen the surface of the sealing reinforcement layer, and make the sealing reinforcement layer laid on the second concave surface flush with the skin laying surface of the molding mold. S6. Prepare the rubber-embedded metal-rubber composite layer; S7. Determine the installation position of the rubber-embedded metal-rubber composite layer relative to the sealing reinforcement layer, brush the base material onto both sides of the rubber-embedded metal-rubber composite layer, and install the rubber-embedded metal-rubber composite layer on the surface of the sealing reinforcement layer on the first recessed surface. S8. The prepreg is used to lay the skin on the surface of the skin, the sealing reinforcement layer and the rubber-embedded metal-rubber composite layer to form a skin, and the prepreg is used to lay the end face of the molding mold to form an end frame. S9. Place the molding mold after laying the prepreg in step S8 into a hot autoclave for pressure curing. After curing, demold to obtain a pressure vessel with embedded metal parts composite material.

2. The method for preparing a composite pressure vessel with embedded metal parts according to claim 1, characterized in that, In step S2, the matrix material is selected as bismaleimide resin, the reinforcing material is selected as T700 continuous carbon fiber, the prepreg is prepared by hot melt prepreg method, and the fiber volume content of the prepreg is 54% to 60%.

3. The method for preparing a composite pressure vessel with embedded metal parts according to claim 1, characterized in that, In step S6, the preparation of the rubber-embedded metal-rubber composite layer includes the following steps: S61. The surface of the embedded metal parts is sandblasted. S62. Grind the surface of the rubber; S63. Cleaning the embedded metal parts after sandblasting and the rubber after grinding. S64. Apply a structural adhesive resistant to resin curing temperature to both sides of the embedded metal part, bond the rubber to the surface of the embedded metal part and lay it flat. S65. The structural adhesive is heated and cured to obtain a rubber-embedded metal-rubber composite layer.

4. The method for preparing a composite pressure vessel with embedded metal parts according to claim 3, characterized in that, The rubber is selected from high-temperature resistant silicone rubber, and the embedded metal part is made of 30CrMnSi material.

5. A pressure vessel made of composite material with embedded metal parts, characterized in that, It is prepared by the preparation method according to any one of claims 1-4.

Images