Integrated forming method of double-curved-surface carbon fiber composite fairing

Abstract

The embodiment of the invention provides an integrated forming method for a double-curved-surface carbon fiber composite fairing, an inner cavity of the fairing is conical, the inner surface of the fairing is an assembling face, and the method comprises the steps that a fairing fake part is manufactured through a pre-manufactured female die; preparing a male mold by utilizing the prepared fairing false part; paving a carbon fiber prepreg on the male mold; closing the male mold and the female mold which are paved with the carbon fiber prepreg to form a combined mold; and carrying out integral bag making on the outer surface of the combined mold, molding the carbon fiber prepreg on the combined mold by utilizing an autoclave according to a curing process, and carrying out demolding and processing to prepare the fairing. According to the embodiment of the invention, the problem that a complex double-curved-surface fairing is difficult to demould can be solved, and the manufacturing cost can be reduced while the apparent mass of the fairing is enhanced.

Description

Technical Field

[0001] The present application relates to the technical field of fairing molding, and in particular to a method for integrated molding of a hyperbolic carbon fiber composite material fairing. Background Art

[0002] Carbon fiber composites are widely used in aerospace, military, and marine fields due to their excellent mechanical properties, high chemical stability, low density, high specific strength, high stiffness, and strong designability. Carbon fiber composites play an important role in composite structures (such as satellite components, aircraft wings, and aircraft engine casings) that require special application scenarios such as high strength, oxidation resistance, fatigue resistance, and light weight. The fairing is a composite part with high precision requirements that is widely used in aviation and aerospace vehicles. It is an important component of launch vehicles, aircraft, and manned spacecraft. Its main function is to maintain the aerodynamic shape during flight and protect the payload in the fairing from the external natural environment and aerodynamic scouring.

[0003] Lightweighting is a long-term key research strategy in the field of aerospace. Studies have shown that when the weight of an aerospace vehicle is reduced by 1 kg, the weight of the corresponding launch vehicle can be reduced by 500 kg. Most of the fairings currently used in aerospace vehicles are made of metal materials, which are very complex in structure and cannot meet the requirements of high performance and lightweight in my country's aircraft upgrade projects; the thermoplastic composite fairings prepared by 3D printing have poor high temperature resistance, are prone to aging, and are prone to surface deformation under aerodynamic loads. Therefore, the use of carbon fiber to prepare fairings can meet the performance requirements of lightweight and fatigue resistance.

[0004] Since the carbon fiber composite fairing structural parts have complex shapes and are mostly hollow internal cavity structures, they usually have extremely high requirements for material properties, molding quality and surface accuracy. If the traditional compression molding process, winding process and RTM molding process are used to prepare the carbon fiber composite fairing, it is difficult to demold the cured part; the method of preparing the fairing by split mold molding has a high tooling manufacturing cost, the apparent quality of the obtained part is also poor, and it is necessary to prepare connecting strips, which increases the number of connecting parts and the difficulty of assembly. In order to solve the above problems, the present application proposes a method for integrated molding of a hyperbolic carbon fiber composite fairing. Summary of the invention

[0005] The embodiment of the present application provides a method for integrated molding of a hyperbolic carbon fiber composite fairing, which can solve the problem of difficult demolding of a complex hyperbolic fairing, and can reduce manufacturing costs while enhancing the apparent quality of the fairing.

[0006] The present application provides a method for integrated molding of a hyperbolic carbon fiber composite fairing, wherein the internal cavity of the fairing is conical and the inner surface is an assembly surface, and the method comprises:

[0007] The fairing dummy is prepared using the prefabricated negative mold;

[0008] Using the prepared fairing dummy to prepare a positive mold;

[0009] Laying carbon fiber prepreg on the male mold;

[0010] The male mold on which the carbon fiber prepreg is laid is combined with the female mold to form a combined mold;

[0011] The outer surface of the combined mold is integrally bagged, and the carbon fiber prepreg on the combined mold is molded according to a curing process using a hot autoclave, and after demoulding and processing, a fairing is prepared.

[0012] In the method for integrated molding of a hyperbolic carbon fiber composite fairing described in the embodiment of the present application, the method of preparing a fairing dummy by using a prefabricated negative mold comprises:

[0013] Using the prefabricated female mold to perform mold splitting and laying carbon fiber prepreg with the same thickness as the final fairing;

[0014] The carbon fiber prepreg on the female mold is successively subjected to autoclave curing, demoulding and processing to obtain the fairing dummy.

[0015] In the method for integrated molding of a hyperbolic carbon fiber composite fairing described in an embodiment of the present application, the female mold comprises a female upper mold and a female lower mold, and the method of using the female mold to split and lay a carbon fiber prepreg having the same thickness as the final fairing comprises:

[0016] The upper mold flap mold and the lower mold flap mold are split and paved with carbon fiber prepreg having the same thickness as the final fairing, and the upper mold flap mold and the lower mold flap mold are connected as a whole by bolts.

[0017] In the method for integrated molding of a hyperbolic carbon fiber composite fairing described in an embodiment of the present application, the method of preparing a positive mold using the prepared fairing dummy comprises:

[0018] placing the fairing dummy on the female mold, and laying an isolation mold on the surface of the fairing dummy;

[0019] Raw silicone is filled into the inner cavity of the fairing dummy and cured at high temperature in a curing furnace. After the raw silicone is hardened, it is demoulded to obtain the male mold, wherein a metal rod with a surface covered with tetrafluoroethylene cloth is placed inside the raw silicone.

[0020] In the method for integrated molding of a hyperbolic carbon fiber composite fairing described in an embodiment of the present application, after the raw silica gel is hardened, demolding to obtain the male mold comprises:

[0021] After the raw silica gel is hardened, the metal rod is pulled out, and the rubber soft film is taken out to complete the demoulding of the male mold.

[0022] In the method for integrated molding of a hyperbolic carbon fiber composite fairing described in an embodiment of the present application, the processing of the demolded initial fairing includes:

[0023] The outer surface of the initial fairing after demoulding is cut and holes are made by using a CNC machine tool, and the cut surface is sealed with edge sealing glue.

[0024] In the method for integrated molding of a hyperbolic carbon fiber composite fairing described in an embodiment of the present application, laying a carbon fiber prepreg on the male mold comprises:

[0025] First, a release cloth is laid on the surface of the male mold, and then the carbon fiber prepreg is laid on the male mold according to the layer laying design.

[0026] In the method for integrated molding of a hyperbolic carbon fiber composite fairing described in an embodiment of the present application, laying the carbon fiber prepreg on the male mold according to the layup design includes:

[0027] According to the layering design, WP3011 / 9A16 / 38% carbon fiber fabric prepreg is laid on the male mold, and EW110 / 9A16 glass fiber is used for local reinforcement.

[0028] In the method for integrated molding of a hyperbolic carbon fiber composite fairing described in the embodiment of the present application, the heading is defined as the fiber laying 0° direction, and the carbon fiber prepreg layup of the initial fairing is as follows:

[0029] [(±45) 2 / (0 / 90) 2 / (±45) 2 / (0 / 90) 2 / (±45) / (0 / 90)]s, 20 layers in total, with a single layer of glass fiber partially laid on the outer surface.

[0030] In the method for integrated molding of a hyperbolic carbon fiber composite fairing described in the embodiment of the present application, the curing system of the autoclave molding process is as follows:

[0031] The curing medium is compressed air;

[0032] The whole curing process is vacuumed;

[0033] Raise the temperature to 81°C±3°C at a rate not exceeding 2°C / min and keep warm for 30min to 35min;

[0034] When the temperature enters the insulation stage, start pressurizing at the fastest rate to 0.6MPa±0.03MPa;

[0035] The combined mold is heated to 125°C ± 5°C at a rate not exceeding 2°C / min and kept warm for 95min to 100min;

[0036] The combined mold is cooled at a cooling rate not exceeding 2°C / min, the temperature of the combined mold is reduced to below 60°C, the pressure is released and the temperature is reduced at the fastest rate, and then the can is opened.

[0037] The embodiment of the present application provides a method for integrated molding of a hyperbolic carbon fiber composite fairing. The method first uses a pre-made female mold to prepare a fairing dummy, then uses the prepared fairing dummy to prepare a male mold, then lays carbon fiber prepreg on the male mold, and closes the male mold with the carbon fiber prepreg to form a combined mold, then the outer surface of the combined mold is bagged as a whole, and the carbon fiber prepreg on the combined mold is molded according to the curing process using an autoclave, and after demoulding and processing, the initial fairing is processed after demoulding to prepare the final fairing. Compared with the split mold molding method, the integrated molding method of the embodiment of the present application solves the problem of difficulty in demoulding of complex hyperbolic parts (fairings), and the fairing obtained has better apparent quality, has advantages such as continuous fibers and accurate layer angles, and reduces manufacturing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0039] Figure 1 A schematic diagram of the process of the integrated molding method of a hyperbolic carbon fiber composite fairing provided in an embodiment of the present application.

[0040] Figure 2Another schematic diagram of the process of the integrated molding method of a hyperbolic carbon fiber composite fairing provided in an embodiment of the present application.

[0041] Figure 3 A schematic diagram of the structure of a hyperbolic carbon fiber composite fairing provided in an embodiment of the present application.

[0042] Figure 4 A schematic diagram of the structure of the female mold provided in an embodiment of the present application.

[0043] Figure 5 A schematic diagram of the preparation process of a fairing dummy provided in an embodiment of the present application.

[0044] Figure 6 Schematic diagram of the preparation process of the male mold provided in the embodiment of the present application. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0046] The present application provides a method for integrated molding of a hyperbolic carbon fiber composite fairing. Figure 1 and Figure 2 The method for integrated molding of a hyperbolic carbon fiber composite fairing is applied to a hyperbolic carbon fiber composite fairing, wherein the internal cavity of the fairing is conical and the inner surface is an assembly surface. The method may include the following steps:

[0047] Step 101, preparing a fairing dummy using a prefabricated negative mold.

[0048] Among them, the overall structure of the hyperbolic carbon fiber composite fairing is as follows Figure 3 As shown, the female mold used for molding is as follows Figure 4 As shown, the outer surface of the part (fairing) is a hyperbolic shape, the internal cavity is conical, and the inner surface is the assembly surface.

[0049] Step 102, preparing a positive mold using the prepared fairing dummy.

[0050] Step 103, laying carbon fiber prepreg on the male mold.

[0051] Step 104, the male mold on which the carbon fiber prepreg is laid is molded together with the female mold to form a combined mold.

[0052] Step 105, bagging the outer surface of the combined mold as a whole, and using an autoclave to shape the carbon fiber prepreg on the combined mold according to a curing process, and after demoulding and processing, a fairing is prepared.

[0053] Among them, due to the small opening of the fairing, it is difficult to carry out the carbon fiber prepreg laying operation by directly using the female mold for molding due to structural limitations, and the material pieces at the R corners are difficult to compact, and the parts are prone to the risk of bridging after molding. Therefore, the female mold is first used to prepare the fairing dummy, and the positive mold is prepared according to the part shape, and then the positive mold is prepared using the prepared fairing dummy. The prepreg is first laid on the positive mold to ensure the continuity of the fibers and the reasonableness of the laying angle reference during the layer design. After the whole is completed, it is transferred to the female mold to form a combined mold, and bags are made on the surface of the combined mold.

[0054] Among them, integrated molding can complete the entire fairing molding process in one mold. The molding process is relatively simple and has the advantages of low cost and high finished product quality.

[0055] In some embodiments, the method of preparing the fairing dummy using a prefabricated negative mold comprises:

[0056] Using the prefabricated female mold to perform mold splitting and laying carbon fiber prepreg with the same thickness as the final fairing;

[0057] The carbon fiber prepreg on the female mold is successively subjected to autoclave curing, demoulding and processing to obtain the fairing dummy.

[0058] In some embodiments, the female mold comprises a female upper mold and a female lower mold, and the process of using the female mold to split and lay carbon fiber prepreg having the same thickness as the final fairing comprises:

[0059] The upper mold flap mold and the lower mold flap mold are split and paved with carbon fiber prepreg having the same thickness as the final fairing, and the upper mold flap mold and the lower mold flap mold are connected as a whole by bolts.

[0060] Specifically, the preparation process of the fairing dummy is as follows: Figure 5 As shown, Figure 5 Mark 1 in the figure is the female upper mold; mark 2 is the female lower mold; mark 3 is laying carbon fiber prepreg in the female upper mold and the female lower mold, and then connecting the female upper mold and the female lower mold into a whole through bolts; mark 4 is curing the carbon fiber prepreg through an autoclave and demoulding the cured parts; mark 5 is the prepared fairing dummy.

[0061] In some embodiments, the method of preparing a positive mold using the prepared fairing dummy comprises:

[0062] placing the fairing dummy on the female mold, and laying an isolation mold on the surface of the fairing dummy;

[0063] Raw silicone is filled into the inner cavity of the fairing dummy and cured at high temperature in a curing furnace. After the raw silicone is hardened, it is demoulded to obtain the male mold, wherein a metal rod with a surface covered with tetrafluoroethylene cloth is placed inside the raw silicone.

[0064] Among them, since the inner surface of the part (fairing) is the assembly surface, placing soft silicone and metal rods in the inner cavity of the fairing can ensure uniform pressure transmission, improve the apparent quality of the inner surface, reduce the assembly gap, and prepare the fairing by integrated molding with the help of autoclave equipment.

[0065] The high temperature aging in the curing furnace is carried out at 170° C. for 6 hours.

[0066] In some embodiments, after the raw silica gel is hardened, demoulding to obtain the male mold comprises:

[0067] After the raw silica gel is hardened, the metal rod is pulled out, and the rubber soft film is taken out to complete the demoulding of the male mold.

[0068] The metal rod can be pulled out to facilitate the removal of the silicone male mold. After the curing is completed, the metal rod can be pulled out, the rubber soft film and auxiliary materials can be removed, and the male mold can be demoulded. The disassembled rubber soft film and metal rod can be reused.

[0069] Specifically, the preparation process of the male mold is as follows: Figure 6 As shown, Figure 6 Mark 6 is the female mold used for the fairing; mark 7 is the fairing dummy; mark 8 is the isolation film laid in the fairing dummy and filled with soft silicone (raw silicone); mark 9 is the isolation film; mark 10 is the soft silicone (raw silicone); mark 11 is the metal rod; mark 12 is the curing furnace to cure the soft silicone and demould the cured male mold; mark 13 is the male mold.

[0070] In some embodiments, the processing of the demolded initial fairing includes:

[0071] The outer surface of the initial fairing after demoulding is cut and holes are made by using a CNC machine tool, and the cut surface is sealed with edge sealing glue.

[0072] Among them, the fairing is processed by CNC lathe for outer surface and drilling. After the outer surface processing is completed, the cutting surface is sealed with edge sealing glue to prevent the fiber end face produced by cutting from being contaminated and damaged.

[0073] In some embodiments, laying carbon fiber prepreg on the male mold comprises:

[0074] First, a release cloth is laid on the surface of the male mold, and then the carbon fiber prepreg is laid on the male mold according to the layer laying design.

[0075] Specifically, a release cloth is first laid on the surface of the male mold, and then laid on the male mold according to the layer design, the male mold is combined with the female mold, the outer surface is integrally bagged, and the carbon fiber prepreg is molded according to the curing process using an autoclave.

[0076] In some embodiments, laying the carbon fiber prepreg on the male mold according to the layer design includes:

[0077] According to the layering design, WP3011 / 9A16 / 38% carbon fiber fabric prepreg is laid on the male mold, and EW110 / 9A16 glass fiber is used for local reinforcement.

[0078] Among them, the hyperbolic fairing is made of carbon fiber composite materials, WP3011 / 9A16 / 38% carbon fiber fabric prepreg is used to lay on the positive mold, and EW110 / 9A16 glass fiber is used for partial reinforcement.

[0079] In some embodiments, the heading is defined as the fiber laying direction of 0°, and the carbon fiber prepreg layup of the initial fairing is as follows:

[0080] [(±45) 2 / (0 / 90) 2 / (±45) 2 / (0 / 90) 2 / (±45) / (0 / 90)]s, 20 layers in total, with a single layer of glass fiber partially laid on the outer surface.

[0081] In some embodiments, the autoclave molding process curing schedule is as follows:

[0082] (1) The curing medium is compressed air; (2) The whole curing process is vacuumed; (3) The temperature is raised to 81°C±3°C at a rate not exceeding 2°C / min and kept at this temperature for 30min to 35min; (4) When the temperature enters the insulation stage, pressurization is started and the temperature is increased to 0.6MPa±0.03MPa at the fastest rate; (5) The combined mold is raised to 125°C±5°C at a rate not exceeding 2°C / min and kept at this temperature for 95min to 100min; (6) The combined mold is cooled at a rate not exceeding 2°C / min, the temperature of the combined mold is reduced to below 60°C, the pressure is released and the temperature is cooled at the fastest rate, and then the can is opened.

[0083] The curing system of the autoclave molding process is based on the carbon fiber prepreg used.

[0084] In summary, this application designs an integrated molding mold for a hyperbolic carbon fiber composite material fairing, which is formed using an autoclave molding process. This can ensure fiber continuity and a reasonable layup angle reference during layup design, while also controlling the thickness and weight of the fairing. This can solve the problem of difficult demolding of complex hyperbolic parts, meet part quality and precision requirements, and reduce weight while also ensuring a smooth aerodynamic surface.

[0085] Compared with the prior art, the significant advantages of this application are: this application designs a low-cost integrated molding tool for fairings, which can realize the integrated molding of hyperbolic fairings, ensure the continuity of fibers and the reasonableness of the layup angle benchmark during the layup design, and overcome the demoulding problem of closed-angle parts, while enhancing the apparent quality of parts and reducing the structural quality, reducing manufacturing costs and improving product competitive advantages. In addition, the thickness and weight of the fairing can be controlled, and the problem of lightweight fairings can be overcome without reducing the actual performance of the fairings.

[0086] All the above optional technical solutions can be arbitrarily combined to form optional embodiments of the present application, which will not be described one by one here.

[0087] In specific implementation, the present application is not limited by the execution order of the various steps described. If no conflict occurs, some steps can be performed in other orders or simultaneously.

[0088] As can be seen from the above, the method for integrated molding of a hyperbolic carbon fiber composite fairing provided in the embodiment of the present application first uses a pre-made female mold to prepare a fairing dummy, then uses the prepared fairing dummy to prepare a male mold, then lays carbon fiber prepreg on the male mold, and closes the male mold with the carbon fiber prepreg laid with the female mold to form a combined mold, then the outer surface of the combined mold is bagged as a whole, and the carbon fiber prepreg on the combined mold is molded according to the curing process using an autoclave, and after demoulding and processing, a fairing is generated. Compared with the split mold molding method, the integrated molding method of the embodiment of the present application solves the problem of the difficulty of demoulding a complex hyperbolic fairing, and the fairing obtained has better apparent quality, has the advantages of fiber continuity and accurate layer angle, and reduces the manufacturing cost.

[0089] The above is a detailed introduction to the integrated molding method of the hyperbolic carbon fiber composite fairing provided in the embodiment of the present application. This article uses specific examples to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and core idea of ​​the present application; at the same time, for those skilled in the art, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for integrally forming a hyperbolic carbon fiber composite fairing, wherein the internal cavity of the fairing is conical and the inner surface is an assembly surface, characterized in that: The method comprises: The fairing dummy is prepared using the prefabricated negative mold; Using the prepared fairing dummy to prepare a positive mold; Laying carbon fiber prepreg on the male mold; The male mold on which the carbon fiber prepreg is laid is combined with the female mold to form a combined mold; The outer surface of the combined mold is integrally bagged, and the carbon fiber prepreg on the combined mold is molded according to a curing process using a hot autoclave, and after demoulding and processing, a fairing is prepared.

2. The method for integrally forming a hyperbolic carbon fiber composite fairing according to claim 1, characterized in that: The method of preparing the fairing dummy by using the prefabricated female mold comprises: Using the prefabricated female mold to perform mold splitting and laying carbon fiber prepreg with the same thickness as the final fairing; The carbon fiber prepreg on the female mold is successively subjected to autoclave curing, demoulding and processing to obtain the fairing dummy.

3. The method for integrated molding of a hyperbolic carbon fiber composite fairing according to claim 2, characterized in that: The female mold comprises a female upper mold and a female lower mold, and the method of using the female mold to split and lay carbon fiber prepreg having the same thickness as the final fairing comprises: The upper mold flap mold and the lower mold flap mold are split and paved with carbon fiber prepreg of the same thickness as the final fairing, and the upper mold flap mold and the lower mold flap mold are connected as a whole by bolts.

4. The method for integrally forming a hyperbolic carbon fiber composite fairing according to claim 1, characterized in that: The method of using the prepared fairing dummy to prepare a positive mold comprises: placing the fairing dummy on the female mold, and laying an isolation mold on the surface of the fairing dummy; Raw silicone is filled into the inner cavity of the fairing dummy and cured at high temperature in a curing furnace. After the raw silicone is hardened, it is demoulded to obtain the male mold, wherein a metal rod with a surface covered with tetrafluoroethylene cloth is placed inside the raw silicone.

5. The method for integrally forming a hyperbolic carbon fiber composite fairing according to claim 4, characterized in that: After the raw silica gel is hardened, demoulding to obtain the male mold comprises: After the raw silica gel is hardened, the metal rod is pulled out, and the rubber soft film is taken out to complete the demoulding of the male mold.

6. The method for integrally forming a hyperbolic carbon fiber composite fairing according to claim 1, characterized in that: The processing of the demoulded initial fairing includes: The outer surface of the initial fairing after demoulding is cut and holes are made by using a CNC machine tool, and the cut surface is sealed with edge sealing glue.

7. The method for integrally forming a hyperbolic carbon fiber composite fairing according to claim 1, characterized in that: The step of laying the carbon fiber prepreg on the male mold comprises: First, a release cloth is laid on the surface of the male mold, and then the carbon fiber prepreg is laid on the male mold according to the layer laying design.

8. The method for integrally forming a hyperbolic carbon fiber composite fairing according to claim 7, characterized in that: The step of laying the carbon fiber prepreg on the male mold according to the layer laying design includes: According to the layering design, WP3011 / 9A16 / 38% carbon fiber fabric prepreg is laid on the male mold, and EW110 / 9A16 glass fiber is used for local reinforcement.

9. The method for integrally forming a hyperbolic carbon fiber composite fairing according to claim 8, characterized in that: The heading is defined as the fiber laying 0° direction, and the carbon fiber prepreg layup of the initial fairing is as follows: [(±45)2 / (0 / 90)2 / (±45)2 / (0 / 90)2 / (±45) / (0 / 90)]s, 20 layers in total, with a single layer of glass fiber partially laid on the outer surface.

10. The method for integrally forming a hyperbolic carbon fiber composite fairing according to claim 1, characterized in that: The curing system of the autoclave molding process is as follows: The curing medium is compressed air; The whole curing process is vacuumed; Raise the temperature to 81°C±3°C at a rate not exceeding 2°C / min and keep warm for 30min to 35min; When the temperature enters the insulation stage, start pressurizing at the fastest rate to 0.6MPa±0.03MPa; The combined mold is heated to 125°C ± 5°C at a rate not exceeding 2°C / min and kept warm for 95min to 100min; The combined mold is cooled at a cooling rate not exceeding 2°C / min, the temperature of the combined mold is reduced to below 60°C, the pressure is released and the temperature is reduced at the fastest rate, and then the can is opened.

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