Method for manufacturing a composite material closed profile fairing

Abstract

This invention relates to the field of composite material preparation, specifically providing a method for preparing a composite material enclosed irregular-shaped fairing, including steps S1: designing the fairing's shell molding mold block, skin molding mold plate, and pressurizing assembly; S2: fabricating the fairing shell, including laying prepreg, placing the shell molding mold block with the prepreg laid on the skin molding mold plate, covering it with a non-porous isolation film, a layer of silicone rubber soft film, and another non-porous isolation film, placing an external pressure frame on the skin molding mold plate, placing fine sand inside the external pressure frame, applying pre-tightening force to the shell molding mold block by pressing the fine sand with an upper pressure plate, placing the shell molding mold block in a curing oven for curing, and then demolding to obtain the fairing shell; S3: fabricating the fairing skin; S4: fabricating the finished fairing. This solution can reduce the number of molds and tooling, lower the requirements for curing equipment, and reduce the preparation cost of the irregular-shaped fairing.

Description

Technical Field

[0001] This invention relates to the field of composite material preparation technology, and in particular to a method for preparing a composite material enclosed irregular-shaped fairing. Background Technology

[0002] Composite materials are the material basis for high-performance products and an important guarantee for the realization of advanced design concepts and technologies, playing a vital role in the development of modern science and technology. High-performance continuous fiber / resin-based composite materials have advantages such as high specific strength, high specific modulus, and corrosion resistance, and are widely used in aerospace, shipbuilding, rail transportation, and launch vehicles.

[0003] In the aerospace field, fairings are commonly used in detection and guidance systems. To reduce gas drag or interference, fairings are typically irregularly shaped structures with enclosed cavities. Enclosed-cavity irregularly shaped fairings, as a common structural form on aircraft, can improve structural efficiency and reduce structural weight while meeting aerodynamic design requirements. The fabrication of composite material enclosed-cavity fairings usually involves separately molding the skin and shell, then gluing them together to form a whole. Current methods for fabricating enclosed-cavity fairings mainly suffer from the following problems:

[0004] 1. Due to the irregular shape of the fairing, the commonly used high-performance composite material molding methods have high requirements for curing equipment and high cost of autoclave curing process, which will greatly increase the overall manufacturing cost of the fairing.

[0005] 2. Traditional metal die-casting processes require the development of complex forming molds, which further increases the manufacturing cost of the fairing and reduces the development efficiency.

[0006] 3. In order to ensure the bonding effect between the irregularly shaped skin and the shell, it is also necessary to design a bonding surface pressure fixture that fits the outline of the shape, which further increases the process cost of product development.

[0007] In summary, designing a low-cost manufacturing process for a composite material enclosed cavity irregularly shaped fairing is an urgent problem to be solved. Summary of the Invention

[0008] To address the aforementioned problems, this invention provides a method for manufacturing a composite material enclosed irregular-shaped fairing. The method involves first designing a shell molding mold block, a skin molding mold plate, and a pressurization assembly for the fairing; then fabricating the fairing shell and fairing skin; and finally, gluing and assembling the fairing shell and fairing skin together to form a fairing assembly, which is then used to manufacture the finished fairing. This invention requires only one molding mold to complete the fabrication of the irregular-shaped fairing, significantly improving manufacturing efficiency and reducing costs.

[0009] To achieve the above objectives, the present invention proposes the following technical solution: a method for preparing a composite material enclosed irregular-shaped fairing, comprising the following steps:

[0010] S1: Design the fairing shell molding mold block, skin molding mold plate, and pressurization assembly; prepare fine sand;

[0011] S2: Fabricate the fairing housing;

[0012] S21: Lay prepreg on the shell forming mold block;

[0013] S22: Place the shell forming mold block with the prepreg laid on it onto the skin forming mold plate, and cover the shell forming mold block with a release film;

[0014] S23: Pour fine sand into the shell forming mold block and apply pre-tightening force to the shell forming mold block through the pressure component;

[0015] S24: After the shell molding block with applied pre-tightening force is placed in the curing oven for curing, it is demolded to obtain the fairing shell;

[0016] S3: Fabricate the fairing skin;

[0017] S31: Lay the prepreg on the skin forming mold plate; cover the skin forming mold plate with a release film;

[0018] S32: Pour fine sand into the skin forming mold plate and apply pre-tightening force to the skin forming mold plate on which the prepreg has been laid through the pressure component;

[0019] S33: The skin forming mold plate with applied pre-tightening force is placed in a curing oven for curing and then demolded to obtain the fairing skin;

[0020] S4: Manufacturing the finished fairing;

[0021] S41: Adhesive bonding and assembly of the fairing shell and fairing skin into a fairing assembly, and then placing the fairing assembly onto the skin forming mold plate.

[0022] S42: Cover the fairing assembly with an isolation membrane;

[0023] S43: Pour fine sand onto the fairing assembly and apply preload to the fairing assembly through the pressurization assembly;

[0024] S44: After curing the fairing assembly, the finished fairing is obtained.

[0025] Preferably, the pressurizing assembly in step S1 includes an outer pressurizing frame, an upper pressurizing plate, and pressurizing bolts; the upper pressurizing plate includes a recessed boss that matches the frame of the outer pressurizing frame and can be pressed downward into the outer pressurizing frame; the pressurizing bolts are located between the upper pressurizing plate and the skin forming mold plate and are located on the outside of the outer pressurizing frame; by applying a preload to the pressurizing bolts, the upper pressurizing plate moves downward and drives the recessed boss to be pressed into the outer pressurizing frame.

[0026] Preferably, in step S23, a preload is applied to the shell forming mold block by a pressurizing component, specifically as follows:

[0027] S231: An external pressure frame is placed on the skin forming mold plate, and the shell forming mold block is located inside the frame of the external pressure frame;

[0028] S232: Add fine sand inside the external pressure frame;

[0029] S233: Install the upper pressure plate above the outer pressure frame, rotate the pressure bolt to move the upper pressure plate downward, and the recessed boss presses the fine sand and applies pre-tightening force to the shell forming mold block;

[0030] In step S32, a preload is applied to the skin forming mold plate on which the prepreg has been laid out using a pressure assembly, specifically as follows:

[0031] S321: Place the outer pressure frame on the outside of the prepreg laid in step S31 on the skin forming mold plate;

[0032] S322: Add fine sand inside the external pressure frame;

[0033] S323: Place the upper pressure plate above the outer pressure frame, rotate the pressure bolt to move the upper pressure plate downward, and the sunken boss presses the fine sand and applies pre-tightening force to the skin forming mold plate.

[0034] Preferably, in step S43, a preload is applied to the fairing assembly using a pressurizing component, specifically as follows:

[0035] S431: Place the external pressure frame on the outside of the fairing assembly on the skin forming mold plate;

[0036] S432: Add fine sand inside the external pressure frame;

[0037] S433: Place the upper pressure plate above the outer pressure frame until the recessed boss contacts the fine sand, and apply preload to the adhesive surfaces of the fairing housing and fairing skin by the weight of the fine sand and the upper pressure plate.

[0038] Preferably, the separator in steps S22, S31 and S42 comprises two non-porous separators and a silicone rubber membrane located between the two non-porous separators.

[0039] Preferably, in step S41, the fairing shell and the fairing skin are glued together to form a fairing assembly, specifically as follows:

[0040] S411: Trial assembly of the fairing shell and fairing skin;

[0041] S412: Grind the adhesive surfaces of the fairing shell and the fairing skin;

[0042] S413: Apply J-256 adhesive to the bonding surfaces and assemble them into a fairing assembly.

[0043] Preferably, the prepreg is T700 carbon fiber / cyanate ester resin, and the single-layer thickness of the prepreg is 0.125±0.05mm.

[0044] Preferably, the prepreg layup angle is [0 / +45 / 90 / -45]. 2S .

[0045] Preferably, in step S24, the curing temperature of the shell forming mold block in the curing oven is 150℃ / 2h~190℃ / 3h.

[0046] Preferably, in step S44, when the fairing assembly is cured, the curing temperature is room temperature and the curing time is 48±1h.

[0047] The beneficial effects of this invention are:

[0048] 1. This invention requires only one molding mold and a curing oven to complete the curing of the irregularly shaped fairing skin and fairing shell, eliminating the need for pressurization using an autoclave. The molding mold is then used as a pressurizing fixture to complete the bonding assembly of the fairing skin and fairing shell adhesive surfaces. The manufacturing process in this invention reduces the requirements for curing equipment, decreases the number of molds and fixtures, and achieves low-cost manufacturing of enclosed cavity irregularly shaped fairings.

[0049] 2. During the pressurization process, it is only necessary to add fine sand into the frame of the outer pressurization frame and then press the fine sand with the upper pressurization plate. The operation is simple. Moreover, the main component of the fine sand is silicon dioxide, which is easy to obtain and has a low cost, which can further reduce the overall manufacturing cost of the fairing.

[0050] 3. In the process of making the fairing assembly into a finished fairing, it is only necessary to use the gravity of fine sand and the upper pressure plate to press the adhesive surface, and cure at room temperature to complete the preparation of the composite material closed cavity irregular fairing. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the structure of the shell forming mold block provided in an embodiment of the present invention.

[0052] Figure 2This is a schematic diagram of the structure of the skin forming mold plate provided in an embodiment of the present invention.

[0053] Figure 3 This is a schematic diagram of the structure of the fairing housing provided in an embodiment of the present invention.

[0054] Figure 4 This is a schematic diagram of the structure of the fairing skin provided in an embodiment of the present invention.

[0055] Figure 5 This is a schematic diagram of the placement of the fairing housing and the external pressure frame provided in an embodiment of the present invention.

[0056] Figure 6 This is a schematic diagram of the upper pressure plate and pressure bolts provided in an embodiment of the present invention.

[0057] Figure 7 This is a schematic diagram of the upper pressure plate provided in an embodiment of the present invention.

[0058] Reference numerals: 1. Shell forming mold block; 2. Skin forming mold plate; 3. Fairing shell; 4. Fairing skin; 5. Outer pressure frame; 6. Upper pressure plate; 7. Pressure bolt; 8. Connecting hole 1; 9. Recessed boss. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of this invention clearer, the following description is provided in conjunction with the appendix. Figure 1-7 The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and do not constitute a limitation thereof.

[0060] A method for preparing a composite material enclosed irregular-shaped fairing includes the following steps:

[0061] S1: Design the fairing shell forming mold block 1, skin forming mold plate 2, and pressurization assembly; prepare fine sand; shell forming mold block 1 and skin forming mold plate 2 are machined from 45# steel; as follows: Figure 5 , Figure 6 As shown, the pressurizing assembly includes an outer pressurizing frame 5, an upper pressurizing plate 6, and pressurizing bolts 7. The pressurizing bolts 7 are standard steel bolts. The skin forming mold plate 2 and the upper pressurizing plate 6 are respectively provided with connecting holes 1 8 and 2. The upper pressurizing plate 6 includes a recessed boss 9 that matches the frame of the outer pressurizing frame 5 and can be pressed downward into the outer pressurizing frame 5. The pressurizing bolts 7 are located between the upper pressurizing plate 6 and the skin forming mold plate 2 and are connected in the connecting holes 1 8 and 2. At the same time, the pressurizing bolts 7 are located on the outside of the outer pressurizing frame 5. By applying a preload to the pressurizing bolts 7, the upper pressurizing plate 6 can move downward and drive the recessed boss 9 to be pressed into the outer pressurizing frame 5.

[0062] S2: Fabricate the fairing housing 3;

[0063] S21: Lay a prepreg on the shell molding die block 1; the prepreg is T700 carbon fiber / cyanate ester resin, the single layer thickness of the prepreg is 0.125±0.05mm, preferably 0.125mm, and the layup angle of the prepreg is [0 / +45 / 90 / -45]. 2S .

[0064] S22: Place the shell forming mold block 1 with the prepreg laid on the skin forming mold plate 2, and cover the shell forming mold block 1 with a release film. The release film includes two layers of non-porous release film and a silicone rubber soft film located between the two layers of non-porous release film.

[0065] S23: Pour fine sand onto the shell forming mold block 1, and apply a preload force to the shell forming mold block 1 through the pressure assembly, specifically:

[0066] S231: Place an external pressure frame 5 on the skin forming mold plate 2, and the shell forming mold block 1 is located inside the frame of the external pressure frame 5;

[0067] S232: Add fine sand into the external pressure frame 5; the main component of the fine sand is silicon dioxide;

[0068] S233: Install the upper pressure plate 6 above the outer pressure frame 5, rotate the pressure bolt 7 to move the upper pressure plate 6 downward, and the recessed boss 9 presses the fine sand and applies pre-tightening force to the shell forming mold block 1.

[0069] S24: The shell forming mold block 1 with pre-tightening force is placed in a curing oven for curing at a curing temperature of 150℃ / 2h~190℃ / 3h. After the shell forming mold block 1 is cured, it is demolded to obtain the fairing shell 3; the thickness of the fairing shell 3 is 2mm.

[0070] S3: Fabricate fairing skin 4;

[0071] S31: Lay prepreg on the skin forming mold plate 2; the prepreg is T700 carbon fiber / cyanate ester resin, the single layer thickness of the prepreg is 0.125±0.05mm, preferably 0.125mm, and the layup angle of the prepreg is [0 / +45 / 90 / -45]. 2S Then cover the skin forming mold plate 2 with a release film, which includes two layers of non-porous release film and a silicone rubber soft film located between the two layers of non-porous release film;

[0072] S32: Pour fine sand onto the skin forming mold plate 2, and apply a pre-tightening force to the skin forming mold plate 2 on which the prepreg has been laid through the pressure component, specifically:

[0073] S321: Place the outer pressure frame 5 on the outside of the prepreg laid in step S31 on the skin forming mold plate 2;

[0074] S322: Add fine sand inside the external pressure frame 5;

[0075] S323: Place the upper pressure plate 6 above the outer pressure frame 5, rotate the pressure bolt 7 to move the upper pressure plate 6 downward, and the sunken boss 9 presses the fine sand and applies pre-tightening force to the skin forming mold plate 2.

[0076] S33: The skin forming mold plate 2 with pre-tightening force is placed in a curing oven for curing at a curing temperature of 150℃ / 2h~190℃ / 3h. After curing, the skin forming mold plate 2 is demolded to obtain the fairing skin 4, which has a thickness of 2mm.

[0077] S4: Manufacturing the finished fairing;

[0078] S41: The fairing shell 3 and the fairing skin 4 are glued together to form a fairing assembly, and then the fairing assembly is placed on the skin forming mold plate 2, specifically:

[0079] S411: Perform trial assembly of fairing housing 3 and fairing skin 4;

[0080] S412: Grind the adhesive surfaces of the fairing housing 3 and the fairing skin 4;

[0081] S413: Apply J-256 adhesive to the bonding surfaces and assemble them into a fairing assembly.

[0082] S42: Cover the fairing assembly with an isolation membrane; the isolation membrane consists of two non-porous isolation membranes and a silicone rubber soft membrane located between the two non-porous isolation membranes, which prevents the surface of the finished fairing from being rough after molding.

[0083] S43: Pour fine sand onto the fairing assembly and apply preload to the fairing assembly through the pressurization assembly, specifically:

[0084] S431: Place the external pressure frame 5 on the outside of the fairing assembly on the skin forming mold plate 2;

[0085] S432: Add fine sand inside the external pressure frame 5;

[0086] S433: Place the upper pressure plate 6 above the outer pressure frame 5 until the recessed boss 9 contacts the fine sand, and apply a pre-tightening force to the adhesive surfaces of the fairing housing 3 and the fairing skin 4 by the gravity of the fine sand and the upper pressure plate 6.

[0087] S44: After curing the fairing assembly, the finished fairing is obtained; wherein the curing temperature is room temperature and the curing time is 48±1h, preferably 48h.

[0088] Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0089] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method of making a composite material closed profile fairing, characterized in that, Includes the following steps: S1: Design the shell forming mold block (1), skin forming mold plate (2) and pressurization assembly for the fairing; prepare fine sand; the shell forming mold block (1) and skin forming mold plate (2) are machined from 45# steel; S2: Fabricate the fairing housing (3); S21: Lay prepreg on the shell forming mold block (1); S22: Place the shell forming mold block (1) with the prepreg laid on it on the skin forming mold plate (2) and cover the shell forming mold block (1) with a release film. S23: Pour fine sand onto the shell forming mold block (1) and apply pre-tightening force to the shell forming mold block (1) through the pressure assembly; S24: Place the shell forming mold block (1) with applied pre-tightening force in the curing oven for curing and then demold to obtain the fairing shell (3). S3: Fabricate fairing skin (4); S31: Lay the prepreg on the skin forming mold plate (2); cover the skin forming mold plate (2) with a release film; S32: Pour fine sand onto the skin forming mold plate (2) and apply pre-tightening force to the skin forming mold plate (2) on which the prepreg has been laid through the pressure component; S33: The skin forming mold plate (2) with applied pre-tightening force is placed in the curing oven for curing and then demolded to obtain the fairing skin (4). S4: Manufacturing the finished fairing; S41: Adhere the fairing housing (3) and fairing skin (4) to form a fairing assembly, and then place the fairing assembly on the skin forming mold plate (2). In step S41, the fairing housing (3) and the fairing skin (4) are glued together to form a fairing assembly, specifically as follows: S411: Perform trial assembly of the fairing housing (3) and the fairing skin (4); S412: Polish the bonding surface between the fairing housing (3) and the fairing skin (4); S413: Apply J-256 adhesive to the bonding surfaces and assemble them into a fairing assembly; S42: Cover the fairing assembly with an isolation membrane; S43: Pour fine sand onto the fairing assembly and apply preload to the fairing assembly through the pressurization assembly; S44: After curing the fairing assembly, the finished fairing is obtained; The pressurizing assembly in step S1 includes an outer pressurizing frame (5), an upper pressurizing plate (6), and a pressurizing bolt (7); the upper pressurizing plate (6) includes a recessed boss (9) that matches the frame of the outer pressurizing frame (5) and can be pressed down into the outer pressurizing frame (5); the pressurizing bolt (7) is located between the upper pressurizing plate (6) and the skin forming mold plate (2) and is located on the outside of the outer pressurizing frame (5); by applying a preload to the pressurizing bolt (7), the upper pressurizing plate (6) moves downward and drives the recessed boss (9) to be pressed into the outer pressurizing frame (5); The separator in steps S22, S31 and S42 includes two non-porous separators and a silicone rubber membrane located between the two non-porous separators. The prepreg is T700 carbon fiber / cyanate ester resin, and the single-layer thickness of the prepreg is 0.125±0.05mm.

2. The method for preparing the composite material enclosed irregular-shaped fairing according to claim 1, characterized in that, In step S23, a preload is applied to the shell forming mold block (1) by the pressurizing component, specifically as follows: S231: Place an external pressure frame (5) on the skin forming mold plate (2), and the shell forming mold block (1) is located inside the frame of the external pressure frame (5); S232: Add fine sand inside the external pressure frame (5); S233: Install the upper pressure plate (6) above the outer pressure frame (5), rotate the pressure bolt (7) to drive the upper pressure plate (6) to move downward, the sunken boss (9) presses the fine sand and applies pre-tightening force to the shell forming mold block (1); In step S32, a preload is applied to the skin forming mold plate (2) on which the prepreg has been laid out using a pressure assembly, specifically as follows: S321: Place the external pressure frame (5) on the outside of the prepreg laid in step S31 on the skin forming mold plate (2); S322: Add fine sand inside the external pressure frame (5); S323: Place the upper pressure plate (6) above the outer pressure frame (5), rotate the pressure bolt (7) to move the upper pressure plate (6) downward, and the sunken boss (9) presses the fine sand and applies pre-tightening force to the skin forming mold plate (2).

3. The method of claim 2, wherein the composite material is a composite material comprising a plurality of layers of a prepreg material. In step S43, a preload is applied to the fairing assembly using a pressurization component, specifically as follows: S431: Place the external pressure frame (5) on the outside of the fairing assembly on the skin forming mold plate (2); S432: Add fine sand inside the external pressure frame (5); S433: Place the upper pressure plate (6) above the outer pressure frame (5) until the sunken boss (9) contacts the fine sand, and apply a pre-tightening force to the adhesive surfaces of the fairing housing (3) and the fairing skin (4) by the gravity of the fine sand and the upper pressure plate (6).

4. The method of claim 1, wherein the composite material is a composite material having a honeycomb structure. The layup angle of the prepreg is [0 / +45 / 90 / -45]2S.

5. The method of claim 1, wherein the composite material is a composite material having a honeycomb structure. In step S24, the curing temperature of the shell forming mold block (1) in the curing oven is 150℃ / 2h~190℃ / 3h.

6. The method of claim 1, wherein the composite material is a composite material having a honeycomb structure. In step S44, when the fairing assembly is cured, the curing temperature is room temperature and the curing time is 48±1h.

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