A forming tool and forming method for a ribbed composite component

Abstract

The present application relates to a kind of forming mould and forming method of ribbed composite component, belong to the field of composite forming.The present application is to solve the problem that the mechanical properties of ribbed composite component cannot be guaranteed due to the limitation of ribbed plate pressure in existing process method.The forming method of the present application includes core mold assembly, laying ribbed plate and part of skin on the core mold, mold assembly, laying the remaining part of skin, encapsulation and curing, etc.The present application is suitable for the forming of ribbed composite component, and for composite components with high requirements on the mechanical properties of ribs, such as antenna mounting bracket, grating, etc., the designed pressure can be used to directional pressurize ribbed plate and adjust the pressure, to improve the mechanical properties of the product.

Description

Technical Field

[0001] This invention relates to the field of composite material molding technology, and in particular to a molding die and molding method for ribbed composite material components. Background Technology

[0002] To ensure the molding quality of ribbed composite components, a co-curing process, where the ribs and the composite component are integrally molded, is typically used. There are two main methods for integral molding of ribbed composite components:

[0003] One method is rigid male mold plus external pressure molding. This method relies solely on the squeezing action between mold blocks during mold installation to pressurize the ribs, as shown in the pressure positioning part designed in patent CN 111907087 A. Mold assembly is difficult, and the squeezing action of the mold blocks is limited. It is generally used for molding composite material components where the ribs only serve as support to prevent deformation. Another example is the box-shaped rib molding fixture designed in patent CN113183485A. This fixture is suitable when the number of ribs is small, such as the two ribs in the example. However, when the number of ribs increases, it is prone to insufficient pressure transmission, resulting in insufficient pressure at the ribs.

[0004] Another method involves a rigid female mold, an expanded core mold, and external pressure molding. The expanded core mold is typically made of silicone and is considered a soft mold. Because the rigidity of the composite material component differs from that of the rigid female mold, the expansion direction of the core mold cannot be controlled during the expansion and pressurization process, leading to uneven stress on the part and affecting its quality. For example, the expanded core molds designed in patents CN 213056086 U, CN113650320 A, and CN207747277U have uncontrolled expansion directions, potentially resulting in large expansion in one direction and small expansion in another. This leads to uneven thickness and glue content in the part, affecting its quality. Summary of the Invention

[0005] The technical problem this invention aims to solve is that existing molding dies for ribbed composite components have limited pressure on the ribs or cannot control the pressure direction, resulting in insufficient or uneven stress on the parts, affecting their quality. Therefore, this invention provides a molding method that can apply directional pressure to the ribs according to design requirements and allows for adjustable pressure.

[0006] The solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0007] In a first aspect, the present invention provides a molding die for a ribbed composite material component, comprising a bottom mold plate, side baffles, a metal core mold, an elastic soft film, fixing bolts, and positioning pins;

[0008] The metal core mold has a cavity, and the elastic soft membrane is embedded in the cavity of the metal core mold to form an expandable core mold;

[0009] The side baffle and expandable core mold are assembled onto the bottom mold plate by fixing bolts and positioning pins to form a molding die for the ribbed composite material component.

[0010] Furthermore, the bottom mold plate, side baffles, fixing bolts, and positioning pins are made of rigid materials such as stainless steel.

[0011] Furthermore, the metal core mold is made of a metal material with a large coefficient of thermal expansion (e.g., exceeding a set threshold), such as aluminum alloy.

[0012] Furthermore, the elastic membrane is made of elastic materials with significant thermal expansion, including but not limited to silicone rubber, polyurethane, etc.

[0013] Furthermore, the ribbed composite material component contains multiple ribs, the number of expandable mandrels (8) is the number of ribs minus 1, and the length of the expandable mandrel is equal to the distance between the ribs × control coefficient, where 0.9 ≤ control coefficient ≤ 1.

[0014] Furthermore, the edge of the elastic membrane that is embedded in the cavity is designed with a chamfer, the chamfer range being 30° to 60°.

[0015] Furthermore, the composite material specifically refers to fiber-reinforced resin-based composite materials, where the fibers include, but are not limited to, carbon fiber, glass fiber, quartz fiber, etc., and the resins include, but are not limited to, epoxy resin, bismaleimide resin, cyanate ester resin, etc.

[0016] Secondly, the present invention provides a method for molding a ribbed composite material component, comprising the following steps:

[0017] 1) The elastic soft membrane is embedded in the cavity of the metal core mold to form an expandable core mold (8);

[0018] 2) Lay prepreg on the expandable core mold and side baffles, with the prepreg thickness being half the thickness of the corresponding ribs;

[0019] 3) Vacuum bag each expandable core mold and side baffle, then evacuate the vacuum.

[0020] 4) Assemble the expandable core mold and side baffles onto the bottom mold plate using fixing bolts and positioning pins. Fill the joints of each expandable core mold and side baffle, as well as the joints between two adjacent expandable core molds (i.e., the ribs), with unidirectional prepreg. After overall encapsulation, vacuum again.

[0021] 5) Lay the prepreg to the required thickness of the component, seal it in a vacuum bag, vacuum it again, and then send it into the molding equipment for curing;

[0022] 6) Demolding: First remove the side baffles, push the product and core mold out of the bottom mold plate as a whole, and finally pull out the expandable core mold from the product.

[0023] The molding die for ribbed composite components provided by this invention employs a combination of a rigid flat mold, a metal core mold with a high coefficient of thermal expansion, and an elastic soft membrane with an even higher coefficient of thermal expansion. The rigid flat mold provides positioning and support for the metal core mold and the elastic soft membrane, which is embedded in the cavity of the metal core mold. When the die is heated, the metal core mold expands slightly, applying a small amount of pressure to the entire component, thus solving the problem of insufficient pressure at the junction of the inner surface skin and the root of the rib. The elastic soft membrane expands significantly, but due to the constraint of the rigid flat mold and the cavity of the metal core mold, it can only expand towards the rib, thereby achieving directional pressure on the rib. Adjusting the thickness of the soft membrane and the depth of the cavity can adjust the amount of pressure applied to the rib. The molding die needs to be used in conjunction with a vacuum bag, using both expansion pressure and external pressure simultaneously to achieve overall pressure application to the composite component, solving the problem of limited pressure application to ribbed composite components.

[0024] This invention is applicable to the molding of ribbed composite material components. For composite material components with high requirements for the mechanical properties of ribs, such as antenna mounting brackets and grids, the ribs can be directionally pressurized according to the design pressure and the pressure can be adjusted to improve the mechanical properties of the parts. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the embodiments or the drawings used will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the mold after assembly.

[0027] Figure 2 A schematic diagram showing that the expandable core mold 8 is composed of a metal core mold 3 and an elastic soft film 4.

[0028] Figure 3 This is a schematic diagram of a ribbed composite material component.

[0029] Figure 4 A schematic diagram of the mold expansion process using pressure applied to the ribs.

[0030] Among them: 1-bottom mold plate, 2-side baffle, 3-metal core mold, 4-elastic soft film, 5-fixing bolt, 6-positioning pin, 7-cavity, 8-expandable core mold, 9-rib plate. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0032] In one embodiment of the present invention, a molding die for a ribbed composite material component is provided. Figure 1 This is a schematic diagram of the molding die in this embodiment. The die includes a bottom mold plate 1, a side baffle 2, a metal core mold 3, an elastic soft film 4, fixing bolts 5, and positioning pins 6. The metal core mold 3 has a cavity 7, and the elastic soft film 4 is embedded in the cavity 7 of the metal core mold 3 to form an expandable core mold 8. The side baffle 2 and the expandable core mold 8 are assembled on the bottom mold plate 1 by fixing bolts 5 and positioning pins 6.

[0033] The molding die in this embodiment includes two side baffles 2 and four expandable core molds 8. Each expandable core mold 8 is formed by an elastic soft membrane 4 embedded in a cavity 7 at the end of a metal core mold 3. The bottom mold plate 1 and the side baffles 2 are made of stainless steel, the metal core mold 3 is made of aluminum alloy, and the elastic soft membrane 4 is made of silicone rubber. It can mold composite material components such as... Figure 3 As shown, the component contains 5 ribs, which are made of glass fiber reinforced epoxy resin composite material.

[0034] In one embodiment of the present invention, a molding method for a ribbed composite material component is provided, including core mold assembly, applying ribs and partial skin onto the core mold, mold assembly, applying the remaining skin, and encapsulation and curing. Specific steps include:

[0035] First, two elastic soft films 4 are embedded in the cavities 7 at both ends of the metal core mold 3 to form an expandable core mold 8. After the glass fiber reinforced epoxy resin prepreg is laid on the expandable core mold 8 and the side baffle 2, the expandable core mold 8 and the side baffle 2 are assembled on the bottom mold plate 1 by fixing bolts 5 and positioning pins 6.

[0036] Then, layers are laid on the entire tooling. After laying, it is sealed in a vacuum bag and cured by external heating and pressure. During the heating process, the external pressure can only be transmitted to the component skin, with the pressure on the outer surface of the skin having the best effect. The inner surface of the skin is improved by the slight thermal expansion of the metal core mold 3 plus some pressure, which improves the forming quality at the junction of the rib and the root of the skin. At the rib, the significant thermal expansion of the elastic soft film 4 applies pressure to the rib. Because the elastic soft film 4 is embedded in the cavity 7, in addition to facing towards... Figure 4The arrows indicate expansion towards rib 9, with no expansion gaps in other directions, thus pressurizing the rib. The depth of cavity 7 and the thickness of elastic membrane 4 are pre-designed. During actual molding, if insufficient pressure is found at the rib, resulting in poor molding quality, the depth of cavity 7 and the thickness of elastic membrane 4 can be increased to adjust the pressure at the rib. Therefore, this molding die overcomes the limitations of traditional rigid male molds in applying pressure to the rib, and the inability to control the direction of pressure in the flexible expansion core mold plus female mold method. It can apply directional pressure to the rib according to the design pressure and adjust the pressure magnitude, improving the mechanical properties of the part.

Claims

1. A molding die for a ribbed composite material component, characterized in that: Includes bottom mold plate (1), side baffle (2), metal core mold (3), elastic soft film (4), fixing bolt (5), and positioning pin (6); The metal core mold (3) is provided with a cavity (7), and the elastic soft membrane (4) is embedded in the cavity of the metal core mold (3) to form an expandable core mold (8). The side baffle (2) and expandable core mold (8) are assembled on the bottom mold plate (1) by fixing bolts (5) and positioning pins (6) to form a molding mold for ribbed composite material components; When the mold is heated, the metal core mold expands slightly and applies pressure to the entire component, improving the forming quality at the junction of the inner surface skin and the root of the rib. The elastic soft film expands significantly, and due to the restriction of the rigid flat mold and the cavity of the metal core mold, it can only expand towards the rib, thereby achieving the effect of directional pressure on the rib. The amount of pressure applied to the rib can be adjusted by adjusting the thickness of the soft film and the depth of the cavity.

2. The molding die according to claim 1, characterized in that: The bottom mold plate (1), side baffle (2), fixing bolt (5), and positioning pin (6) are made of rigid materials.

3. The molding die according to claim 1, characterized in that: The metal core mold (3) is made of a metal material with a large coefficient of thermal expansion.

4. The molding die according to claim 1, characterized in that: The elastic membrane (4) is made of an elastic material with significant thermal expansion.

5. The molding die according to claim 1, characterized in that: The ribbed composite material component contains multiple ribs, and the number of expandable mandrels (8) is the number of ribs minus 1. The length of the expandable mandrels (8) is equal to the distance between the ribs × the control coefficient, and 0.9 ≤ control coefficient ≤ 1.

6. The molding die according to claim 1, characterized in that: The edge of the elastic membrane (4) that is embedded in the cavity (7) is designed with a chamfer, the chamfer range being 30° to 60°.

7. The molding die according to claim 1, characterized in that: The composite material specifically refers to fiber-reinforced resin-based composite material, wherein the fiber includes at least one of the following: carbon fiber, glass fiber, quartz fiber, and the resin includes at least one of the following: epoxy resin, bismaleimide resin, cyanate ester resin.

8. A molding method for a ribbed composite material component, characterized in that, Molding a ribbed composite material component using the molding die according to any one of claims 1 to 7 includes the following steps: 1) The elastic soft membrane (4) is embedded in the cavity (7) of the metal core mold (3) to form an expandable core mold (8). 2) Lay prepreg on the expandable core mold (8) and the side baffle (2), with the prepreg thickness being half the thickness of the corresponding rib; 3) Vacuum bag each expandable core mold (8) and side baffle (2), and then evacuate the vacuum. 4) Assemble the expandable core mold (8) and side baffle (2) onto the bottom mold plate (1) using fixing bolts (5) and positioning pins (6). Fill the joints of each expandable core mold (8) and side baffle (2) and the joints between two adjacent expandable core molds, i.e., the ribs, with unidirectional prepreg. After the whole assembly is sealed, vacuum it again. 5) Lay the prepreg to the required thickness of the component, seal it in a vacuum bag, vacuum it again, and then send it into the molding equipment for curing; 6) When demolding, first remove the side baffle (2), push the product and core mold out of the bottom mold plate (1) as a whole, and finally pull the core mold out of the product.

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