A method for integral curing of metal heating film and composite material

Abstract

The application provides a metal heating film and composite material integrated solidification forming method, and specifically comprises the following steps: preparing a homogeneous resin metal heating film; performing composite layering of a fiber prepreg and the metal heating film; performing internal pressurization in a flexible pressurizer; performing a curing reaction; demolding; and machining. Superstructure metal material and resin material are prepared, a layer of resin material is coated on the surface of the superstructure metal material, the resin material is combined with the resin material, a homogeneous resin metal heating film is formed, the metal heating film is placed in an oven for curing treatment, and the combination of the resin material and the superstructure metal material is ensured to be firm. The metal heating film and composite material integrated conformal solidification forming method based on heat conduction provided by the application adopts the metal heating film and composite material integrated conformal solidification forming technology, so that the forming structure of the composite material structural member is simplified, and the internal temperature is uniform.

Description

Technical Field

[0001] This invention belongs to the field of composite material forming technology, specifically relating to a method for integrally curing and forming a metal heating film and a composite material. Background Technology

[0002] Fiber composite materials have outstanding advantages such as the lowest density, high specific strength, high specific stiffness, corrosion resistance, high temperature resistance, and fatigue resistance. However, the internal structure of composite material components is a non-uniform structure with multiple ribs, windows, and flanges of varying sizes. The temperature field of traditional autoclave molding is uneven, resulting in large deviations in the molding consistency, temperature resistance, mechanical properties, and stability of the components, which seriously affects the reliability and large-scale application of composite material components. Specifically, the reasons why the products cannot be homogeneously formed at present are as follows: (1) Due to the heating method and air duct during the autoclave molding process, the circumferential temperature difference of the product is large (temperature difference ≥ 30℃); (2) The fiber composite material / electromagnetic functional metal layer adopts a secondary adhesive curing process, which is complex, has a long cycle, concentrated interface stress, and is easy to debond.

[0003] Meanwhile, traditional autoclave molding is inefficient and energy-intensive, resulting in high production costs and long cycles for composite material structural components, which cannot meet the defense industry's demands for low-cost, large-scale mass production and rapid response. Therefore, developing key technologies that are low-cost, high-efficiency, and low-energy-consumption can help solve the bottlenecks in composite material manufacturing, improve production efficiency, reduce costs, and meet the needs of the rapidly developing composite materials industry. Summary of the Invention

[0004] The purpose of this invention is to provide a conformal curing method for integrally forming a metal heating film and a composite material based on thermal conduction. By adopting the conformal curing technology for integrally forming a metal heating film and a composite material, the technical problems of complex forming structure and uneven internal temperature of composite material structural parts are solved.

[0005] A method for integrally curing a metal heating film and a composite material includes the following steps:

[0006] Step S1: Prepare a homogeneous resin-metal heating film;

[0007] Step S2: Perform composite layup of fiber prepreg and metal heating film;

[0008] Step S3: Pressurize the flexible pressurizer to cure the reaction;

[0009] Step S4: Demolding and machining.

[0010] More preferably, in step S1, finite element software is used to simulate the shape and size of the metal heating film, thereby simulating and separating the heat conduction temperature field; the superstructure metal material is embedded in homogeneous resin (resin with the same composition as the composite material), and the heat conduction temperature field is simulated to determine and optimize the layup density and resistance of the superstructure metal material, thereby achieving uniform temperature distribution of the irregular structure.

[0011] More preferably, in step S1, a superstructure metal material and a resin material are prepared, a metal heating film is made according to the design requirements, and the superstructure metal material is cut into the corresponding shape according to the design requirements.

[0012] A layer of resin material is coated on the surface of the superstructure metal material to form a good bond between the resin material and the metal heating film. The metal heating film is then placed in an oven for curing to ensure a strong bond between the resin material and the superstructure metal material.

[0013] More preferably, in step S2, a composite material is attached to the outer surface of the inner metal mold, a metal heating film is attached to the outside of the composite material, and then the outer metal mold is attached to the outer surface of the composite material and the metal heating film.

[0014] Prepare fiber prepreg, lay up the fiber prepreg according to the angle and number of layers, and attach the surface of the fiber prepreg to the outer surface of the metal mold.

[0015] More preferably, in step S2, when the surface of the fiber prepreg is laid on the surface of the metal outer mold, the temperature uniformity inside the metal outer mold is tested by powering on, and then the composite material after composite layup is molded together, with the superstructure metal material placed between the metal outer mold and the metal inner mold; during this process, vacuum bag pressing is performed, and the wires and temperature measuring thermocouples are sealed through the vacuum bag strip without leakage, ensuring tight bonding and improving the quality of composite layup.

[0016] More preferably, in step S3, after the fiber prepreg and metal heating film composite layup are prepared, they are placed in a flexible pressurizer for pressure curing reaction. The flexible pressurizer is started to pressurize the composite layup. Under specific temperature and pressure, the resin materials in the composite layup will undergo a curing reaction, which improves its density and bonding strength, and ensures the stability of the entire composite structure.

[0017] More preferably, in step S4, the composite layup after pressure curing is demolded, and the surface of the demolded composite layup is treated to make its surface smooth and flat. Finally, the composite product is machined according to the product design requirements.

[0018] It should be noted that the resin material and homogeneous resin mentioned in this solution are actually the same term used in different scenarios.

[0019] The positive effects of this invention are as follows:

[0020] (1) This solution has the advantages of low cost, low energy consumption and high efficiency. It uses a metal heating film based on heat conduction and composite molding to quickly and accurately transfer heat and apply pressure to the composite material, further accelerating the curing process. It has the advantages of shortening heating time, improving production efficiency, optimizing resin curing quality and increasing consistency, thus improving the quality stability of the product.

[0021] (2) To address the bottleneck issues of complex secondary adhesive bonding processes and stress concentration at the interface, a functional / structural / manufacturing integrated technology was developed by using a super-structured metal heater / composite material co-curing molding based on thermal conduction, which solved the problem of difficult integral molding of composite materials.

[0022] (3) The innovation of this scheme is that the homogeneous resin is embedded in the surface of the composite material and made into one piece after the pressure is applied; in addition, the flexible pressure technology is adopted and the pressure is applied by a flexible pressure device to ensure the uniformity of the pressure field; the metal material is used for heating in this scheme, which can transmit a certain electromagnetic wave, unlike the previous graphene heating, the temperature field and pressure field are more uniform and the efficiency is higher. Attached Figure Description

[0023] Figure 1 This is a front view of the fiber prepreg laid on a metal mold in Embodiment 1 of the present invention.

[0024] Figure 2 This is a schematic diagram of the metal heating film prepared by homogeneous resin and superstructure metal material in Example 1 of the present invention.

[0025] Figure 3 This is a schematic diagram of the connection structure of the metal heating film, the outer metal mold, and the inner metal mold in Embodiment 1 of the present invention.

[0026] Figure 4 This is a schematic diagram of the vacuum bag compression structure in Embodiment 1 of the present invention.

[0027] The reference numerals in the attached drawings are as follows: 1. Fiber prepreg; 2. Mold; 3. Homogeneous resin; 4. Ultrastructure metal material; 5. Metal heating film; 6. Metal outer mold; 61. Composite material; 7. Metal inner mold; 8. Power supply; 9. Vacuum bag; 10. Sealing strip. Detailed Implementation

[0028] To more clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution.

[0029] Example 1

[0030] See Figures 1-4 A conformal curing method for integrally curing a metal heating film and a composite material based on thermal conduction specifically includes the following steps:

[0031] Step S1: Preparation of homogeneous resin 3 and metal heating film 5, as follows Figure 2 Homogeneous resin 3 refers to a resin material with the same composition as composite material 61;

[0032] The composite material 61 in this solution can be fiber composite material, glass fiber composite material, fiber ironing cloth, etc.

[0033] Specifically, the analysis focuses on the product thickness. Heating will generate a temperature difference at the point where the thickness changes, similar to the temperature difference between the outer and inner surfaces of the product. By simulating the temperature difference at the point where the product changes thickness, and by designing the shape and size of the metal heating film 5, a temperature difference balance can be achieved.

[0034] Step S2: Perform composite layup of fiber prepreg 1 and metal heating film 5;

[0035] Step S3: Pressurize the flexible pressurizer to cure the reaction;

[0036] Step S4: Demolding and machining.

[0037] In step S1, prepare the required superstructure metal material 4 and resin material, make the metal heating film 5 according to the design requirements, cut the superstructure metal material 4 into the corresponding shape according to the design requirements, and lay it in the mold.

[0038] A layer of resin material is coated on the surface of the superstructure metal material 4 to form a bond with the resin material, forming a homogeneous resin 3 metal heating film 5. The metal heating film 5 is placed in an oven for curing to ensure that the resin material and the superstructure metal material 4 are firmly bonded.

[0039] In step S2, based on the simulation design results, the fiber prepreg 1 is laid up according to the angle and number of layers, for example, by manual or electric iron heat-pressure coupling. Vacuum degassing is required during the process to ensure tight bonding and improve the quality of composite layup. Specifically, vacuum pre-compactment is performed by vacuuming with vacuum bag 9. The angle and number of layers of different composite material 61 structural components are different, which is common knowledge for those skilled in the art and will not be described in detail here. The pre-prepared metal heating film 5 is glued to the inner surface of the metal outer mold 6 with adhesive. The temperature uniformity inside the metal outer mold 6 is tested by powering on. Then, the composite material 61 after composite layup is molded together.

[0040] When testing the internal temperature uniformity of the metal outer mold 6 by powering on, the specific parameters are: voltage -5V DC, temperature difference ≤1℃, operating range room temperature -280℃, and temperature difference standard for uniform temperature field is ±2℃. Then, the composite material 61 after composite layup is molded.

[0041] "Mold assembly" refers to combining the metal outer mold 6 with the composite material 61 structural component. The product refers to the blank that has reached the required thickness after being laid up, i.e., the composite material 61 structural component. In short, the composite material 61 is attached to the outer surface of the metal inner mold, and the metal heating film 5 is attached to the outside of the composite material 61. Then, the metal outer mold 6 is attached to the outer surface of the composite material 61 and the metal heating film 5 to press out the shape. Both the metal inner mold 7 and the metal outer mold 6 are cylindrical.

[0042] During the power-on test, specifically, the power supply 8 is connected in series with the metal heating film 5 using a wire. The current direction A and the temperature transfer direction B are shown in the attached diagram. Figure 3 As shown.

[0043] When evacuating the vacuum bag 9, simply pass the wires and temperature measuring thermocouple through the sealing strip 10 on the vacuum bag 9 to ensure no air leakage.

[0044] In step S3, after the preparation of the composite layup of fiber prepreg 1 and metal heating film 5 is completed, it is placed in a flexible pressurizer for pressure curing reaction. The flexible pressurizer is started to pressurize the composite layup. Under the heat conduction temperature field and the pressure field of the flexible pressurizer, the components of the thermosetting resin (i.e., the resin material mentioned above) undergo curing and crosslinking reaction. The curing and crosslinking reaction is the most basic reaction of the thermosetting resin (i.e., the resin material mentioned above), which is a technical term and will not be described in detail.

[0045] The so-called flexible pressurization is similar to placing the molded product into a vacuum bag 9. The vacuum bag 9 needs to be sealed with adhesive strips, and a vacuum P is drawn to ensure that the vacuum bag 9 is tightly attached to the mold 2. This allows pressure to be applied quickly and accurately to the surface of the mold 2, achieving a uniform distribution of the pressure field. Figure 4 As shown; and the metal heating film 5 is designed to fit the shape of the product and is applied to the surface of the composite material 61.

[0046] It should be noted that the vacuum bag 9 pressurization in this scheme actually includes two steps. First, a vacuum is drawn and atmospheric pressure is used to achieve pre-compaction. Then, pressurization is performed, which acts as a flexible pressurizer to carry out the pressure curing reaction between the resin materials. This is hereby explained.

[0047] After the composite layup is cured under pressure, it is demolded (from both the inner metal mold 7 and the outer metal mold 6). The surface of the demolded composite product is then treated to make it smooth and flat. Finally, the composite product is machined according to the product design requirements (in this scheme, the composite layup is the process, and the cured product is the composite product, which can then be machined).

[0048] Example 2

[0049] Based on Example 1, Example 2 is presented here. The flexible pressurizer in this scheme can also be a flexible pipe with both ends closed, and then pressurization is applied into the flexible pipe.

[0050] Example 3

[0051] Based on Example 1, Example 3 is introduced.

[0052] In the original step S1, finite element software (such as Abaqus) is used to simulate the shape and size of the metal heating film 5, thereby simulating and separating the heat conduction temperature field. Based on different structures, the superstructure metal material 4 is embedded in the homogeneous resin 3, and the heat conduction temperature field is simulated to determine and optimize the layup density and resistivity of the superstructure metal material 4, achieving uniform temperature distribution in the irregular structure. Regarding the specific simulation method, those skilled in the art can easily implement it using finite element software, and it will not be detailed here.

[0053] The technical features of this invention not described can be implemented by or using existing technology, and will not be repeated here. Of course, the above description is not a limitation of this invention, and this invention is not limited to the examples above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of this invention should also be within the protection scope of this invention.

Claims

1. A method of integrally forming a metal heating film with a composite material, the method comprising: providing a metal heating film; providing a composite material; and combining the metal heating film and the composite material to form an integrated structure. Specifically comprising the following steps: Step S1: preparing the homogeneous resin (3) metal heating film (5); In the step S1, the superstructure metal material (4) and the resin material are prepared, the metal heating film (5) is made according to the design requirements, the superstructure metal material (4) is made into a superstructure according to the design requirements; In the step S1, the resin material is coated on the surface of the superstructure metal material (4) to combine with the resin material, and the homogeneous resin (3) metal heating film (5) is formed, and the metal heating film (5) is placed in an oven for curing treatment to ensure that the resin material is firmly combined with the superstructure metal material (4); Step S2: composite layering of the fiber prepreg (1) and the metal heating film (5); In the step S2, the composite material (61) is attached to the outer surface of the metal inner mold (7), and the metal heating film (5) is attached to the outer side of the composite material (61), and then the metal outer mold (6) is attached to the outer surface of the composite material (61) and the metal heating film (5); The fiber prepreg (1) is prepared, and the fiber prepreg (1) is layered according to the angle and the number of layers, and the fiber prepreg (1) is attached to the outer surface of the metal outer mold (6); In the step S2, when the fiber prepreg (1) is attached to the surface of the metal outer mold (6), the temperature uniformity inside the metal outer mold (6) is tested, and then the composite material (61) after the composite layering is molded; Then, vacuum bag pressing treatment is carried out, and the wires and temperature measuring thermocouples can pass through the vacuum bag (9) without air leakage, so as to ensure close fitting and improve the quality of the composite layering; Step S3: internal pressure of the flexible pressurizer and curing reaction; In the step S3, after the preparation of the fiber prepreg (1) and the metal heating film (5) composite layering, the flexible pressurizer is started to pressurize the composite layering, and the curing crosslinking reaction between the components of the thermosetting resin is carried out under the heat conduction temperature field and the pressure field of the flexible pressurizer. Step S4: demolding and machining.

2. The method of claim 1, wherein the metal heating film is integrally formed with the composite material. In the step S3, after the preparation of the fiber prepreg (1) and the metal heating film (5) composite layering, the flexible pressurizer is started to pressurize the composite layering, and the curing reaction occurs between the resin materials in the composite layering.

3. The method of claim 1, wherein the metal heating film is integrally formed with the composite material. In the step S4, the composite layering after the pressurization and curing is demolded, the surface of the demolded composite layering is treated to make it smooth and flat, and finally the composite product is machined according to the design requirements of the product.

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