A process and a mould structure for the compression moulding of a sandwich beam of composite foam

Abstract

The application relates to a composite material foam sandwich mouth-shaped beam mould pressing forming process method and a mould structure, and belongs to the technical field of composite material forming manufacturing. The composite material foam sandwich mouth-shaped beam mould pressing forming process method comprises the following steps: laying a layer of glue film on the surface of a foam core and sealing by using a sealing system; placing the foam core with the laid glue film and the sealing system into an oven to perform curing according to the process parameters of the glue film; laying mouth-shaped beam prepreg on the foam core with the cured glue film on the surface; placing the mould with the mouth-shaped beam semi-finished blank into a press bed heating plate to heat and press until the mould is closed; completing the laying of the remaining five layers of prepreg; placing the mouth-shaped beam blank with the completed prepreg laying into a mouth-shaped beam forming mould, placing the mould on the press bed heating plate after the upper and lower moulds are closed; after the heating and curing are completed, cooling to below 60 DEG C to release the pressure and take out the mould. The application solves the pressing problem of the four surfaces of the mouth-shaped beam; and the process method effectively improves the loss-free qualified rate and the surface quality of the mouth-shaped beam.

Description

Technical Field

[0001] This invention relates to a molding process and mold structure for composite foam sandwich beams, belonging to the field of composite material molding and manufacturing technology. Background Technology

[0002] Composite material components are widely used in the aerospace field due to their high strength, high temperature resistance, and fatigue resistance; in some aircraft, composite material parts even account for 70% of the components. Currently, for composite material mandrels, small-sized parts can be molded using various methods such as male mold forming and silicone rubber molding; for large-sized mandrels, water-soluble mandrels or low-temperature melting mandrels are often used. However, the molding structure and processing methods of conventional foam core mandrels suffer from poor compression on the two side walls, resulting in low surface quality. Summary of the Invention

[0003] The purpose of this invention is to solve the problems existing in the prior art and provide a composite material foam sandwich beam compression molding process and mold structure to improve part quality and reduce production costs.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: a method for molding composite foam sandwich beams using compression molding, comprising the following steps. (1) Lay a layer of adhesive film on the surface of the foam core, seal it with a sealing system, and vacuum for more than 30 minutes; (2) Place the foam core with adhesive film and the sealing system into the oven and cure according to the process parameters of the adhesive film; (3) Lay the prepreg of the mouth-shaped beam on the foam core with the surface cured adhesive film. When there are 5 layers of prepreg remaining, put the foam core with the prepreg of the mouth-shaped beam into the mouth-shaped beam forming mold and close the mold. (4) Place the mold containing the semi-finished blank of the mouth-shaped beam on the heating plate of the press and heat and press it until the mold is closed. Then keep it warm and pressurized for 15 minutes, cool it down to room temperature and take it out. (5) Complete the laying of the remaining 5 layers of prepreg; (6) Place the prepreg blank into the prepreg molding mold, close the mold and place it on the press heating plate; heat and cure according to the process parameters of the layup material; after the heat curing is completed, cool down to below 60°C and release the pressure to remove the mold.

[0005] Preferably, in step (1), the sealing system is assembled from sealing material, breathable material, isolation material and vacuum bag.

[0006] Preferably, in step (2), the process parameters of the adhesive film are as follows: The vacuum system has a vacuum degree of not less than 0.095 MPa. The temperature is increased to (130±5)℃ at a rate of not more than 3℃ / min, and kept at that temperature for 3-4 hours. The temperature is then reduced to below 60℃ at a rate of not more than 2℃ / min. The vacuum is then removed, the auxiliary materials that make up the vacuum system are removed, and the foam core with the surface cured adhesive film is taken out.

[0007] Preferably, in step (4), the mold containing the semi-finished blank of the mouth-shaped beam is placed on the heating plate of the press and heated. After being kept at (40±5)℃ for 30 minutes, it is pressed to close the mold.

[0008] Preferably, in step (6), the temperature is raised to (80±5)℃ at a rate of no more than 3℃ / min on the press heating plate, held for 30-40 minutes, and pressurized to 3-3.5MPa.

[0009] Preferably, in step (6), the process parameters of the layup material are as follows: based on the temperature of the press heating plate, the temperature is further increased to (125±5)℃ and kept warm for 1.5-2 hours.

[0010] Preferably, in step (6), under pressure holding conditions, the cooling rate is no more than 2℃ / min to cool down to below 60℃.

[0011] A molding die structure for a composite foam sandwich beam includes an upper die and a lower die, used in the compression molding process described above, wherein the mating surfaces of the upper die and the lower die coincide with the diagonal surfaces of the composite foam sandwich beam.

[0012] Compared with the prior art, the present invention has the following advantages: it solves the problem of pressure on the four sides of the shaped beam; the process method effectively improves the non-destructive pass rate and surface quality of the shaped beam. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the mold structure in an embodiment of the present invention; Figure 2 This is a cross-sectional view of the composite foam sandwich beam in an embodiment of the present invention; Figure 1 In the middle, 1. Upper mold; 2. Lower mold; Figure 2 In the middle, 3. Foam core; 4. Adhesive film; 5. Prepreg. Detailed Implementation

[0014] The following is in conjunction with the appendix Figure 1-2The present invention is further described in detail as follows: A method for molding a composite foam sandwich-type beam involves hardening a foam core 3, then applying prepreg 5 to its surface. When five layers of prepreg remain, the foam core 3 and the layers are assembled into a vacuum bag sealing system using a sealing material. After vacuuming and pre-compacting for about 30 minutes, the foam core 3 with some prepreg layers is placed into a molding mold and the mold is closed. The mold is heated on a press, and after the heating is completed and the temperature drops to room temperature, the foam core 3 is removed, thus completing the application of the remaining prepreg. The blank of the foam sandwich-type beam is placed into the molding mold, and the upper mold 1 and lower mold 2 are closed. The mold containing the blank of the beam is placed on the heating plate of the press and cured according to the curing parameters of the composite material.

[0015] The specific process includes the following steps: (1) Lay a layer of adhesive film 4 on the surface of foam core 3, assemble the sealing system with sealing material, breathable material, isolation material and vacuum bag, and vacuum for more than 30 minutes; (2) Place the foam core 3 with adhesive film 4 and the sealing system into an oven. The vacuum degree of the vacuum system is not less than 0.095MPa. Heat the foam core 3 to (130±5)℃ at a rate of not more than 3℃ / min, keep it at the temperature for 3-4 hours, and cool it down to below 60℃ at a rate of not more than 2℃ / min. Remove the vacuum, remove the auxiliary materials that make up the vacuum system, and take out the foam core 3 with the adhesive film 4 cured on the surface. (3) Lay the prepreg 5 of the mouth-shaped beam onto the foam core 3 with the cured adhesive film 4 on the surface. When there are 5 layers of prepreg remaining, place the foam core with the prepreg of the mouth-shaped beam, i.e., the semi-finished blank of the mouth-shaped beam, into the mouth-shaped beam forming mold, such as... Figure 1 As shown, upper mold 1 and lower mold 2 are joined together; (4) Place the mold containing the semi-finished blank of the mouth-shaped beam on the heating plate of the press and heat it. After holding it at (40±5)℃ for 30 minutes, press it to close the mold and then hold it at the temperature and pressure for 15 minutes. Cool it down to room temperature and take it out. (5) Complete the laying of the remaining 5 layers of prepreg; (6) Place the prepreg blank into the prepreg forming mold structure, such as... Figure 1 As shown, after the upper mold 1 and lower mold 2 are closed, they are placed on the heating plate of the press and heated to (80±5)℃ at a rate of no more than 3℃ / min, and kept at that temperature for 30-40 minutes. The pressure is then increased to 3-3.5MPa. The temperature is further increased to (125±5)℃ and kept at that temperature for 1.5-2 hours. Under pressure, the temperature is reduced to below 60℃ at a rate of no more than 2℃ / min, and the pressure is released and the mold is removed.

[0016] As a preferred embodiment of this invention, a molding die structure for a composite foam sandwich beam includes an upper die and a lower die, used in the compression molding process described above. The mating surfaces of the upper and lower dies coincide with the diagonal surfaces of the composite foam sandwich beam, i.e., the cavities of the upper and lower dies, which are arranged opposite to each other, are used to form the four sides of the composite foam sandwich beam, each side including two flange surfaces. Figure 2 The two vertical planes), the two web planes ( Figure 2 (Two horizontal planes in the middle).

Claims

1. A method for molding composite foam sandwich beams using compression molding, characterized in that: Includes the following steps, (1) Lay a layer of adhesive film on the surface of the foam core, seal it with a sealing system, and vacuum for more than 30 minutes; (2) Place the foam core with adhesive film and the sealing system into the oven and cure according to the process parameters of the adhesive film; (3) Lay the prepreg of the mouth-shaped beam on the foam core with the surface cured adhesive film. When there are 5 layers of prepreg remaining, put the foam core with the prepreg of the mouth-shaped beam into the mouth-shaped beam forming mold and close the mold. (4) Place the mold containing the semi-finished blank of the mouth-shaped beam on the heating plate of the press and heat and press it until the mold is closed. Then keep it warm and pressurized for 15 minutes, cool it down to room temperature and take it out. (5) Complete the laying of the remaining 5 layers of prepreg; (6) Place the prepreg blank into the prepreg molding mold, close the upper and lower molds and place it on the press heating plate; heat and cure according to the process parameters of the layup material; after the heat curing is completed, cool down to below 60°C and release the mold; wherein the mold closing surface of the upper and lower molds coincides with the diagonal surface of the composite foam sandwich prepreg.

2. The composite material foam sandwich beam compression molding process according to claim 1, characterized in that: In step (1), the sealing system is assembled from sealing material, breathable material, isolation material and vacuum bag.

3. The composite material foam sandwich beam compression molding process according to claim 1, characterized in that: In step (2), the process parameters of the adhesive film are as follows: the vacuum degree of the vacuum system is not less than 0.095MPa, the temperature is raised to (130±5)℃ at a rate of not more than 3℃ / min, the temperature is kept for 3-4 hours, the temperature is lowered to below 60℃ at a rate of not more than 2℃ / min, the vacuum is removed, the auxiliary materials that make up the vacuum system are removed, and the foam core with the surface cured adhesive film is taken out.

4. The composite material foam sandwich beam compression molding process according to claim 1, characterized in that: In step (4), the mold containing the semi-finished blank of the mouth-shaped beam is placed on the heating plate of the press and heated. After being kept at (40±5)℃ for 30 minutes, pressure is applied to close the mold.

5. The composite material foam sandwich beam compression molding process according to claim 1, characterized in that: In step (6), the temperature is raised to (80±5)℃ at a rate of no more than 3℃ / min on the press heating plate, held for 30-40 minutes, and pressurized to 3-3.5MPa.

6. The composite material foam sandwich beam compression molding process according to claim 1 or 5, characterized in that: In step (6), the process parameters for the layup material are as follows: based on the temperature of the press heating plate, continue to heat up to (125±5)℃ and keep warm for 1.5-2 hours.

7. The composite material foam sandwich beam compression molding process according to claim 1, characterized in that: In step (6), under pressure holding conditions, the cooling rate is no more than 2℃ / min to cool down to below 60℃.

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