A method for molding a composite material by co-curing a soft mold with a double-sided I-shaped cross-section reinforcing frame

Abstract

The application discloses a kind of I-shaped section reinforcing frame double-sided soft mold co-curing composite material forming method, comprising the following steps: S10, workpiece preparation;S20, mold closing;S30, filling;S40, sheet laying;S50, core mold installation;S60, packaging;S70, curing;The beneficial effects of the present application are: through the above method, the upper C-shaped workpiece, the lower C-shaped workpiece is laid on the compaction tooling with a male mold to improve the forming quality, reduce the skill operation difficulty, improve the laying efficiency;By realizing the compaction tooling, the upper C-shaped workpiece, the lower C-shaped workpiece co-curing connection, it is different from the need for twice tank with co-bonding, reduces manufacturing cost.

Description

Technical Field

[0001] This invention relates to a method for molding composite materials with a double-sided soft mold co-curing of an I-shaped cross-section reinforcing frame. Background Technology

[0002] In the field of advanced composite material manufacturing technology, especially in the aerospace industry, increasingly higher demands are being placed on the manufacturing methods of high-performance composite I-beam cross-section reinforced frames. Advanced composite materials, due to their lightweight, high strength, high modulus, fatigue resistance, corrosion resistance, good designability, and processability, have become ideal materials for large structures and overall structures. With the application of composite materials in the main load-bearing components of large passenger aircraft, and the shift in UAV frame materials from engineering plastics to carbon fiber composites, new demands are being placed on the manufacturing technology of composite I-beam cross-section reinforced frames.

[0003] Traditional composite material molding processes mainly fall into three bonding methods: secondary bonding, co-bonding, and co-curing. While secondary bonding and co-bonding are widely used, they suffer from drawbacks such as long molding cycles, numerous assembly steps, and poor bond strength. Co-curing molding, due to its short processing cycle and significantly reduced cost, has attracted widespread attention from researchers. However, existing co-bonding and secondary bonding molding processes have many limitations in practical applications, such as inconsistent molding quality, high operational difficulty, and low production efficiency. These problems restrict the further application of composite materials in aerospace and other fields. Therefore, this invention proposes a double-sided soft mold co-curing composite material molding method for I-shaped cross-section reinforcing frames to solve the aforementioned problems. Summary of the Invention

[0004] The purpose of this invention is to provide a method for molding composite materials with a double-sided soft mold for reinforcing frame with an I-shaped cross section, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for molding a double-sided soft mold co-curing composite material with an I-shaped cross-section reinforcing frame includes the following steps:

[0007] S10. Workpiece preparation:

[0008] Prepare the upper C-shaped workpiece and the lower C-shaped workpiece, and lay the upper C-shaped workpiece and the lower C-shaped workpiece on the two sets of compaction fixtures respectively;

[0009] S20, Mold Closure:

[0010] The upper C-shaped workpiece and the compaction fixture connected to the upper C-shaped workpiece are inverted and placed on the lower C-shaped workpiece, so that the upper C-shaped workpiece and the lower C-shaped workpiece are tightly aligned.

[0011] S30, Filling:

[0012] Carbon twisted wire is filled into the triangular corner of the mold closing seam between the upper C-shaped workpiece and the lower C-shaped workpiece in S20 until the side end faces of the upper C-shaped workpiece and the lower C-shaped workpiece are flat.

[0013] S40, Sheet installation:

[0014] After S30 is completed, edge strips are laid on both end faces of the upper and lower C-shaped workpieces to form an I-beam preform.

[0015] S50, Core Mold Installation:

[0016] Remove the compaction fixture from the upper C-shaped workpiece and replace it with a core mold of the same size and structure as the compaction fixture.

[0017] S60, Package:

[0018] The I-beam preform in S50, along with a set of compaction fixtures and a set of core molds, are vacuum-sealed and then compacted.

[0019] S70, Curing:

[0020] The preformed I-beam, along with a set of compaction fixtures and a set of core molds, is placed into an autoclave for heating and curing. Once curing is complete, the compaction fixtures and core molds are removed and placed into the I-beam cross-section reinforcing frame.

[0021] As an improvement to the above technical solution, the compaction fixture has a U-shaped structure, and the core mold is made of flexible high-temperature resistant rubber material.

[0022] As an improvement to the above technical solution, in S10, the upper C-shaped workpiece and the lower C-shaped workpiece are laid in front of the two sets of compaction fixtures, and prepreg is laid on the surface of the compaction fixtures.

[0023] As an improvement to the above technical solution, when the surface of the compaction fixture is covered with prepreg, vacuum sealing and compaction are performed every three layers until the U-shaped structure of the compaction fixture is compatible with the upper C-shaped workpiece and the lower C-shaped workpiece.

[0024] As an improvement to the above technical solution, the prepreg is made of epoxy resin and carbon fiber unidirectional tape.

[0025] As an improvement to the above technical solution, in S70, the curing pressure is 0.3-0.8MPa, the curing temperature is 180±6℃, and the curing time is 120-180min.

[0026] As an improvement to the above technical solution, in S70, when the curing pressure is applied, it is gradually increased from 0.1MPa to the applied pressure to maintain uniform stress on the compaction fixture.

[0027] As an improvement to the above technical solution, in S10, the upper C-shaped workpiece and the lower C-shaped workpiece have the same structural size.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] The above method enables the upper and lower C-shaped workpieces to be laid with positive molds on the compaction fixture, thereby improving the molding quality, reducing the difficulty of operation, and increasing the laying efficiency.

[0030] By achieving co-curing and connection of the compaction fixture, the upper C-shaped workpiece, and the lower C-shaped workpiece, unlike co-bonding which requires a second injection into the can, manufacturing costs are reduced.

[0031] By co-curing the upper C-shaped workpiece and the lower C-shaped workpiece, the need for standard parts for riveting and fixing is eliminated, thus reducing the weight of the parts;

[0032] This molding method, by applying uniform pressure, can effectively avoid the problem of internal delamination and also solve the problem of assembly tolerance distribution. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structural forming of the present invention.

[0034] In the diagram: 10. Compactor; 20. Upper C-shaped workpiece; 30. Lower C-shaped workpiece; 40. Carbon twisted wire; 50. Flanged strip plate; 60. Core mold. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Example:

[0037] like Figure 1 As shown in the figure, this embodiment proposes a method for molding a composite material with a double-sided soft mold and reinforcing frame of an I-shaped cross-section, including the following steps:

[0038] S10. Workpiece preparation:

[0039] Prepare the upper C-shaped workpiece 20 and the lower C-shaped workpiece 30, and lay the upper C-shaped workpiece 20 and the lower C-shaped workpiece 30 on the two sets of compaction fixtures 10 respectively;

[0040] S20, Mold Closure:

[0041] The upper C-shaped workpiece 20 and the compaction fixture 10 connected to the upper C-shaped workpiece 20 are inverted and placed on the lower C-shaped workpiece 30, so that the upper C-shaped workpiece 20 and the lower C-shaped workpiece 30 are tightly aligned.

[0042] S30, Filling:

[0043] Carbon twisted wire 40 is filled into the triangular corner of the mold closing seam between the upper C-shaped workpiece 20 and the lower C-shaped workpiece 30 in S20 until the side end faces of the upper C-shaped workpiece 20 and the lower C-shaped workpiece 30 are flat.

[0044] S40, Sheet installation:

[0045] After S30 is completed, edge strips 50 are laid on both end faces of the upper C-shaped workpiece 20 and the lower C-shaped workpiece 30 to form an I-beam preform.

[0046] S50, Core Mold Installation:

[0047] Remove the compaction fixture 10 from the upper C-shaped workpiece 20 and replace it with a core mold 60 of the same size and structure as the compaction fixture 10.

[0048] S60, Package:

[0049] The I-beam preform in S50, along with a set of compaction fixtures 10 and a set of core molds 60, are vacuum sealed and compacted.

[0050] S70, Curing:

[0051] The preformed I-beam body, which has been packaged in S60, along with a set of compaction fixtures 10 and a set of core molds 60, are sent into a hot autoclave for heating and curing. After curing, the compaction fixtures 10 and core molds 60 are removed and placed into the I-shaped cross-section reinforcing frame.

[0052] In this embodiment, the above method enables the upper C-shaped workpiece 20 and the lower C-shaped workpiece 30 to be laid on the compaction fixture 10, so as to improve the molding quality, reduce the difficulty of operation, and improve the laying efficiency.

[0053] By achieving co-curing connection of compaction fixture 10, upper C-shaped workpiece 20, and lower C-shaped workpiece 30, unlike co-bonding which requires secondary injection into the can, manufacturing costs are reduced.

[0054] The upper C-shaped workpiece 20 and the lower C-shaped workpiece 30 are co-cured and molded, eliminating the need for standard parts for riveting and fixing, thus reducing the weight of the parts;

[0055] This molding method, by applying uniform pressure, can effectively avoid the problem of internal delamination and also solve the problem of assembly tolerance distribution.

[0056] Specifically, the compaction fixture 10 has a U-shaped structure, and the core mold 60 is made of flexible high-temperature resistant rubber material.

[0057] In this embodiment, the flexible high-temperature resistant rubber material can maintain stable performance in high-temperature environments. At the same time, it can avoid stress concentration in the upper C-shaped workpiece 20 and the lower C-shaped workpiece 30 under high temperature and high pressure, which would cause local damage to the web surface of the upper C-shaped workpiece 20 and the lower C-shaped workpiece 30, resulting in scrapping of the parts. In addition, the compaction tooling 10 of the upper C-shaped workpiece 20 is replaced with the core mold 60, which reduces the hard contact between the hard parts under high temperature and high pressure curing, and ensures the product qualification rate.

[0058] Specifically, in S10, the upper C-shaped workpiece 20 and the lower C-shaped workpiece 30 are laid in front of the two sets of compaction fixtures 10, and prepreg is laid on the surface of the compaction fixtures 10.

[0059] Specifically, when the prepreg is laid on the surface of the compaction fixture 10, vacuum sealing and compaction are performed every three layers until the U-shaped structure of the compaction fixture 10 is compatible with the upper C-shaped workpiece 20 and the lower C-shaped workpiece 30.

[0060] Specifically, the prepreg is made of epoxy resin and carbon fiber unidirectional tape.

[0061] In this embodiment, the mechanical strength of the I-shaped cross-section reinforcing frame can be effectively guaranteed by using a combination of epoxy resin and carbon fiber unidirectional tapes.

[0062] Specifically, in S70, the curing pressure is 0.3-0.8 MPa, the curing temperature is 180±6℃, and the curing time is 120-180 min.

[0063] Specifically, in S70, when applying the curing pressure, it is gradually increased from 0.1 MPa to the applied pressure to maintain uniform stress on the compaction fixture 10.

[0064] Specifically, in S10, the upper C-shaped workpiece 20 and the lower C-shaped workpiece 30 have the same structural size.

[0065] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for molding a composite material with a double-sided soft mold and co-curing of an I-shaped cross-section reinforcing frame, characterized in that: Includes the following steps: S10. Workpiece preparation: Prepare the upper C-shaped workpiece (20) and the lower C-shaped workpiece (30), and lay the upper C-shaped workpiece (20) and the lower C-shaped workpiece (30) on the two sets of compaction fixtures (10) respectively; S20, Mold Closure: The upper C-shaped workpiece (20) and the compaction fixture (10) connected to the upper C-shaped workpiece (20) are upside down and placed on the lower C-shaped workpiece (30), so that the upper C-shaped workpiece (20) and the lower C-shaped workpiece (30) are closely aligned. S30, Filling: Carbon twisted wire (40) is filled into the triangular corner of the mold closing seam between the upper C-shaped workpiece (20) and the lower C-shaped workpiece (30) in S20 until the side end faces of the upper C-shaped workpiece (20) and the lower C-shaped workpiece (30) are flat. S40, Sheet installation: After S30 is completed, edge strips (50) are laid on both end faces of the upper C-shaped workpiece (20) and the lower C-shaped workpiece (30) to form an I-beam preform; S50, Core Mold Installation: Remove the compaction fixture (10) from the upper C-shaped workpiece (20) and replace it with a core mold (60) of the same size and structure as the compaction fixture (10). S60, Package: The I-beam preform in S50, along with a set of compaction fixtures (10) and a set of core molds (60), are vacuum sealed and compacted. S70, Curing: The preformed I-beam, after being packaged in S60, along with a set of compaction fixtures (10) and a set of core molds (60), is sent into a hot autoclave for heating and curing. After curing, the compaction fixtures (10) and core molds (60) are removed and placed into the I-shaped cross-section reinforcing frame. The compaction fixture (10) has a U-shaped structure, and the core mold (60) is made of flexible high-temperature resistant rubber material; In S10, the upper C-shaped workpiece (20) and the lower C-shaped workpiece (30) are laid in front of the two sets of compaction fixtures (10), and prepreg is laid on the surface of the compaction fixtures (10).

2. The method for molding a double-sided soft mold co-curing composite material with an I-shaped cross-section reinforcing frame according to claim 1, characterized in that: When the surface of the compaction fixture (10) is covered with prepreg, vacuum sealing and compaction are performed every three layers until the U-shaped structure of the compaction fixture (10) is compatible with the upper C-shaped workpiece (20) and the lower C-shaped workpiece (30).

3. The method for molding a double-sided soft mold co-curing composite material with an I-shaped cross-section reinforcing frame according to claim 2, characterized in that: The prepreg is made of epoxy resin and carbon fiber unidirectional tape.

4. The method for molding a double-sided soft mold co-curing composite material with an I-shaped cross-section reinforcing frame according to claim 1, characterized in that: In S70, the curing pressure is 0.3-0.8 MPa, the curing temperature is 180±6℃, and the curing time is 120-180 min.

5. The method for molding a double-sided soft mold co-curing composite material with an I-shaped cross-section reinforcing frame according to claim 1, characterized in that: In S70, when the curing pressure is applied, it is gradually increased from 0.1 MPa to the applied pressure to keep the compaction fixture (10) under uniform stress.

6. The method for molding a double-sided soft mold co-curing composite material with an I-shaped cross-section reinforcing frame according to claim 1, characterized in that: In S10, the upper C-shaped workpiece (20) and the lower C-shaped workpiece (30) have the same structural size.

Images