Metal heating film and composite material integrated curing forming method

Abstract

The invention provides a metal heating film and composite material integrated curing forming method. The method specifically comprises the following steps that a homogeneous resin metal heating film is prepared; composite laying of the fiber prepreg and the metal heating film is carried out; pressurizing in a flexible pressurizer, and carrying out curing reaction; and demolding and machining. A superstructure metal material and a resin material are prepared, the surface of the superstructure metal material is coated with a layer of resin 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 a drying oven to be subjected to curing treatment, and it is ensured that the resin material is firmly combined with the superstructure metal material. According to the metal heating film and composite material integrated conformal curing forming method based on heat conduction, the metal heating film and composite material integrated conformal curing forming technology is adopted, so that the forming structure of a composite material structural part is simplified, and it is guaranteed that the internal temperature is uniform.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite material forming, and in particular relates to a method for integrally curing and forming a metal heating film and a composite material. Background Art

[0002] Fiber composite materials have outstanding advantages such as minimum density, high specific strength, high specific stiffness, corrosion resistance, high temperature resistance, and fatigue resistance. However, the interior of composite structural parts is a special-shaped structure with multiple ribs, multiple windows, and multiple flanges of different 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 structural parts, which seriously affects the reliability and large-scale application of composite structural parts. Specifically, the reasons why products cannot be homogeneously formed at this stage 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°C); (2) The fiber composite material / electromagnetic functional metal layer adopts a secondary adhesive curing process, which is complex, has a long cycle, concentrates interface stress, and is easy to debond.

[0003] At the same time, the low efficiency and high energy consumption of traditional autoclave molding lead to high production costs and long production cycles for composite structural parts, which cannot meet the low-cost, large-scale mass production and rapid response needs of the defense industry. Therefore, the development of low-cost, high-efficiency, and low-energy key technologies will help solve the bottleneck problems faced by composite manufacturing, help improve production efficiency, reduce costs, and meet the needs of the rapid development of composite materials. Summary of the invention

[0004] The purpose of the present invention is to provide a method for conformal curing of a metal heating film and a composite material based on heat conduction, which adopts the conformal curing technology of a metal heating film and a composite material to solve the technical problems of complex forming structure and uneven internal temperature of composite material structural parts.

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

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

[0007] Step S2: performing composite lamination of fiber prepreg and metal heating film;

[0008] Step S3: pressurizing in the flexible pressurizer to perform a curing reaction;

[0009] Step S4: demoulding and machining.

[0010] Preferably, in step S1, finite element software is used to simulate the shape and size of the metal heating film to simulate and separate the heat conduction temperature field; the superstructure metal material is embedded in a homogeneous resin (a resin with the same composition as the composite material), and the heat conduction temperature field is simulated to determine and optimize the laying density and resistance of the superstructure metal material to achieve uniform temperature distribution of the special-shaped structure.

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

[0012] A layer of resin material is coated on the surface of the superstructure metal material to form a good bond with the resin material to form a homogeneous resin metal heating film, and the metal heating film is placed in an oven for curing to ensure that the resin material and the superstructure metal material are firmly bonded.

[0013] More preferably, in the step S2, the composite material is pasted on the outer surface of the metal inner mold, the metal heating film is pasted on the outer side of the composite material, and then the outer surface of the composite material and the metal heating film is pasted on the metal outer mold;

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

[0015] Preferably, in step S2, when the surface of the fiber prepreg is laid on the surface of the metal outer mold, power is turned on to test the temperature uniformity inside the metal outer mold, and then the composite material after the composite layer is molded, and the superstructure metal material is placed between the metal outer mold and the metal inner mold; in this process, vacuum bag pressing treatment is performed, and the wires and temperature measuring thermocouples are passed through the vacuum bag strips without leakage, thereby ensuring a tight fit and improving the quality of the composite layer.

[0016] More preferably, in step S3, after the preparation of the fiber prepreg and the metal heating film composite ply is completed, it is placed in a flexible pressurizer for a pressurized curing reaction, the flexible pressurizer is started, and the composite ply is pressurized. Under specific temperature and pressure, a curing reaction will occur between the resin materials in the composite ply, thereby improving its density and bonding strength, thereby ensuring the stability of the entire composite structure.

[0017] More preferably, in step S4, the composite ply after pressurization and curing is demoulded, and the composite ply after demoulding is surface treated to make its surface smooth and flat, and finally the composite product is machined according to the product design requirements.

[0018] It should be noted that the resin material and homogeneous resin in this solution are actually the same expressions in different scenarios, and this is hereby explained.

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

[0020] (1) This solution has the advantages of low cost, low energy consumption and high efficiency. The use of metal heating film based on heat conduction and composite material composite molding can 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, thereby improving the quality stability of the product.

[0021] (2) In order to address the bottleneck problems of complex secondary bonding process and concentrated interface stress, a function / structure / manufacturing integrated technology was formed through the co-curing molding of super-structure metal heater / composite materials based on heat conduction, which solved the problem of difficulty in integrated molding of composite materials.

[0022] (3) The innovation of this scheme is that homogeneous resin is embedded in the surface of the composite material, and the two become one after the pressurization. In addition, flexible pressurization technology is adopted, and the pressurization is performed using a flexible pressurizer to ensure the uniformity of the pressure field. The metal material used for heating in this scheme can transmit certain electromagnetic waves. Unlike the previous graphene heating, the temperature field and pressure field are more uniform and the efficiency is higher. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0024] Figure 2 This is a schematic diagram of the structure of preparing a metal heating film using homogeneous resin and super-structured 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 metal outer mold and the metal inner mold in Example 1 of the present invention.

[0026] Figure 4 Schematic diagram of the structure of the vacuum bag press in Example 1 of the present invention.

[0027] Among them, the figure markings are: 1. fiber prepreg; 2. mold; 3. homogeneous resin; 4. superstructure 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 DESCRIPTION

[0028] In order to more clearly illustrate the technical features of this solution, this solution is described below through specific implementation methods.

[0029] Example 1

[0030] See also Figure 1-Figure 4 A method for conformal curing of a metal heating film and a composite material based on heat conduction, specifically comprising the following steps:

[0031] Step S1: homogeneous resin 3 and metal heating film 5 are prepared, such as Figure 2 , the homogeneous resin 3 refers to a resin material having the same composition as the composite material 61;

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

[0033] The specific analysis is on the thickness of the product. Heating will produce a temperature difference at the place where the thickness changes, similar to the temperature difference between the outer surface and the inner surface of the product. By simulating the temperature difference at the variable thickness of the product and designing the shape and size of the metal heating film 5, the temperature difference balance is achieved.

[0034] Step S2: performing composite lamination of the fiber prepreg 1 and the metal heating film 5;

[0035] Step S3: pressurizing in the flexible pressurizer to perform a curing reaction;

[0036] Step S4: demoulding and machining.

[0037] In step S1, the required superstructure metal material 4 and resin material are prepared, the metal heating film 5 is manufactured according to the design requirements, the superstructure metal material 4 is cut into corresponding shapes according to the design requirements, and is laid 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 to form a homogeneous resin 3 metal heating film 5, and 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, according to the simulation design results, the fiber prepreg 1 is laid according to the angle and number of layers, for example, by manual or electric iron heat-pressure coupling. Vacuum degassing treatment is required in the process to ensure close fitting and improve the quality of the composite laying. Specifically, vacuum bag 9 is used for pre-compaction by vacuuming. Among them, different composite material 61 structural parts have different angles and numbers of layers, which is common knowledge known to technicians in this field and will not be described in detail here. The pre-prepared metal heating film 5 is adhered to the inner surface of the metal outer mold 6 with an adhesive, and the temperature uniformity inside the metal outer mold 6 is tested by power-on, and then the composite material 61 after composite laying is molded.

[0040] When the temperature uniformity inside the metal outer mold 6 is tested by power-on, the specific parameters are voltage -5V DC, temperature difference ≤1°C, operating range room temperature -280°C, temperature difference standard of uniform temperature field is ±2°C, and then the composite material 61 after composite lamination is molded.

[0041] Mold closing refers to combining the metal outer mold 6 and the composite material 61 structural parts together. The product refers to the blank that reaches the required thickness after lamination, that is, the composite material 61 structural parts. In brief, 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. The metal inner mold 7 and the metal outer mold 6 are both cylindrical.

[0042] During the power-on test, specifically, the power source 8 is connected in series with the metal heating film 5 by a wire, and the current direction A and the temperature transfer direction B refer to the attached Figure 3 shown.

[0043] When the vacuum bag 9 is evacuated, the electric wire and the temperature measuring thermocouple are passed through the sealing strip 10 on the vacuum bag 9 to ensure that there is no air leakage.

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

[0045] The so-called flexible pressurization is similar to putting the molded product into the vacuum bag 9. The seal of the vacuum bag 9 needs to be connected with a rubber strip, and vacuum is drawn P, so that the vacuum bag 9 is closely attached to the mold 2, so that the pressure is quickly and accurately applied to the surface of the mold 2 to achieve a uniform distribution of the pressure field, such as Figure 4 As shown; and the metal heating film 5 is designed according to the shape of the product and is applied to the surface of the composite material 61.

[0046] It should be noted that the pressurization of the vacuum bag 9 in this solution actually includes two steps: first, evacuation is performed and atmospheric pressure is used to press down to achieve pre-compaction; then, pressurization is performed, that is, it acts as a flexible pressurizer to carry out a pressurized curing reaction between the resin materials. This is specially explained.

[0047] The pressurized and cured composite layer is demolded (from both the metal inner mold 7 and the metal outer mold 6), and the composite product after demolding is surface treated to make its surface smooth and flat. Finally, according to the product design requirements, the composite product is machined (in this solution, the composite layer is a process, and after curing, it is a composite product, and the composite product can be machined).

[0048] Example 2

[0049] Based on the embodiment 1, the present embodiment 2 is derived. The flexible pressurizer in the present solution can also be a flexible pipe with both ends closed, and then pressurizing the flexible pipe.

[0050] Example 3

[0051] Based on Example 1, this Example 3 is derived.

[0052] In the original step S1, finite element software (such as abaqus software, etc.) is used to simulate the shape and size of the metal heating film 5 to simulate and separate the heat conduction temperature field; the superstructure metal material 4 is embedded in the homogeneous resin 3 according to different structures, and the heat conduction temperature field is simulated to determine and optimize the laying density and resistance of the superstructure metal material 4 to achieve uniform temperature distribution of the special-shaped structure. Regarding the specific simulation method, for those skilled in the art, the specific operation can be achieved through finite element software, which will not be described in detail here.

[0053] Technical features not described in the present invention can be achieved through or by adopting existing technologies and will not be described in detail here. Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention should also fall within the scope of protection of the present invention.

Claims

1. A method for integrally curing and forming a metal heating film and a composite material, characterized in that: The specific steps include the following: Step S1: preparing a homogeneous resin (3) and a metal heating film (5); Step S2: performing composite lamination of the fiber prepreg (1) and the metal heating film (5); Step S3: applying pressure in the flexible pressurizer and performing a curing reaction; Step S4: demoulding and machining.

2. The method for integrally curing and forming a metal heating film and a composite material according to claim 1, characterized in that: In the step S1, a superstructure metal material (4) and a resin material are prepared, a metal heating film (5) is manufactured according to design requirements, and the superstructure metal material (4) is manufactured into a superstructure according to design requirements.

3. The method for integrally curing and forming a metal heating film and a composite material according to claim 2, characterized in that: In the step S1, a resin material is coated on the surface of the superstructure metal material (4) to bond with the resin material to form a homogeneous resin (3) metal heating film (5), and the metal heating film (5) is placed in an oven for curing to ensure that the resin material is firmly bonded to the superstructure metal material (4).

4. The method for integrally curing and forming a metal heating film and a composite material according to claim 1, characterized in that: In the step S2, the composite material (61) is attached to the outer surface of the metal inner mold (7), the metal heating film (5) is attached to the outer side of the composite material (61), and then the outer surfaces of the composite material (61) and the metal heating film (5) are attached to the metal outer mold (6); A fiber prepreg (1) is prepared, the fiber prepreg (1) is layered according to an angle and a number of layers, and the surface of the fiber prepreg (1) is laid on the outer surface of the metal outer mold (6).

5. The method for integrally curing and forming a metal heating film and a composite material according to claim 3, characterized in that: In the step S2, when the surface of the fiber prepreg (1) is laid on the surface of the metal outer mold (6), the temperature uniformity inside the metal outer mold (6) is tested by powering on, and then the composite material (61) after the composite layer is molded; Then, vacuum bag pressing is performed, and the wires and the temperature measuring thermocouple are passed through the vacuum bag (9) without air leakage, so as to ensure a tight fit and improve the quality of the composite layer.

6. The method for integrally curing and forming a metal heating film and a composite material according to claim 1, characterized in that: In the step S3, after the preparation of the composite laminate of the fiber prepreg (1) and the metal heating film (5) is completed, it is placed in a flexible pressurizer for a pressurized curing reaction, and the flexible pressurizer is started to pressurize the composite laminate, so that a curing reaction occurs between the resin materials in the composite laminate.

7. The method for integrally curing and forming a metal heating film and a composite material according to claim 1, characterized in that: In the step S4, the composite laminate after pressurization and curing is demoulded, and the composite laminate after demoulding is surface treated to make its surface smooth and flat. Finally, the composite product is machined according to the product design requirements.

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