Method and apparatus for integrally forming large composite fairings

Abstract

The present application relates to the field of launch vehicle satellite fairing forming technology, and provides a large-size composite fairing integral forming method and device, the method comprises the following steps: step S1: manufacturing a fairing forming die; step S2: cutting and laying the pre-impregnated honeycomb on the die surface in sequence for curing and shaping; step S3: processing the height of part of the shaped honeycomb; step S4: laying the outer skin on the die surface and pasting a layer of adhesive film on the surface; step S5: sequentially laying the shaped honeycomb on the surface of the outer skin; and step S6: continuing to lay the inner skin on the surface of the laid honeycomb core material. In the present application, the pre-impregnated honeycomb curing and shaping die and the composite fairing forming die are the same die, the honeycomb core material is matched with the height of the fairing shape after curing and shaping, and the problem of forming quality caused by the mismatch of the die surface due to the manufacturing error of different dies is effectively solved.

Description

Technical Field

[0001] This invention relates to the field of launch vehicle satellite fairing molding technology, specifically to a method and apparatus for integral molding of a large-size composite material fairing. Background Technology

[0002] As a key component of a launch vehicle, the fairing plays a crucial role in providing aerodynamic protection, thermal protection, and payload protection during the rocket's passage through the atmosphere. The fairing must possess excellent mechanical properties, a lightweight structure, and good wave transmission performance to meet overall design requirements; therefore, composite materials are typically used in its design and manufacture.

[0003] Composite fairings are typically composed of a ball head, conical sections, and cylindrical sections, with a shell-like honeycomb sandwich structure. They mainly consist of two thin layers of resin-based fiber composite panels and a thicker honeycomb core, and can be manufactured using co-bonding, secondary bonding, and co-curing processes. Compared to co-bonding and secondary bonding, the significant advantage of co-curing for composite fairings lies in its optimized manufacturing process, reducing production costs by decreasing the number of curing cycles, and producing a component with strong structural integrity. However, controlling the molding quality during the process is more difficult, and the manufacturing process requires higher technical expertise. Furthermore, the complex shape of the integrally molded fairing (the ball head and conical sections exhibit a hyperbolic shape) and its large size further increase the difficulty of manufacturing fairings using co-curing technology. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method and apparatus for integral molding of large-size composite material fairings.

[0005] A method for integral molding of a large-size composite material fairing according to the present invention is characterized by comprising the following steps: Step S1: Manufacture a fairing molding die, the die being used for curing and shaping the honeycomb core material and molding the composite material fairing; Step S2: Cut the pre-impregnated honeycomb and lay it on the mold surface in sequence for curing and shaping. The cured and shaped honeycomb serves as the core part of the composite material fairing. Step S3: Process the height of some of the shaped honeycomb structures; Step S4: Lay the outer skin on the mold surface. The pre-compression operation is performed as required during the laying process. After the outer skin is laid, apply a layer of adhesive film to the surface. Step S5: The shaped honeycomb is laid sequentially onto the surface of the outer skin, and a layer of adhesive film is then laid on the inner surface of the honeycomb core material; Step S6: Continue to lay the inner skin on the surface of the already laid honeycomb core material. The laying process shall be carried out with pre-compression as required. After the laying is completed, it shall be cured according to the co-curing molding technology.

[0006] Preferably, the fairing structure includes a ball head, a conical section, and a cylindrical section, all of which are made of composite material honeycomb sandwich structure.

[0007] Preferably, the composite honeycomb sandwich structure includes an outer skin, an outer film, a shaped honeycomb, an inner film, and an inner skin arranged sequentially from the outside to the inside.

[0008] Preferably, both the inner and outer skins are made of glass fiber and / or cyanate ester resin materials, and the shaped honeycomb is made of aramid paper honeycomb.

[0009] Preferably, the composite material fairing is obtained by integral molding of the ball head, cone segment and column segment combined with the co-curing of the composite material sandwich structure. After the two fairings are formed, they are assembled by interlocking metal connecting trusses and connecting frames.

[0010] Preferably, in step S2, the honeycomb core material already fixed on the mold is placed in a curing oven or autoclave for curing; the curing parameters are: 160℃±5℃, hold for 3~4h, average heating rate 0.5~1.2℃ / min, vacuum pressure ≤-0.05MPa.

[0011] Preferably, in step S3, the core height of the partially shaped honeycomb is processed, and the processed partially shaped honeycomb includes a column-cone transition area and a cover circumferential area.

[0012] Preferably, the 0° direction of the inner and outer skin layers is consistent with the warp direction of the prepreg, and the layering angle sequence is +45 / 0 / -45 / 0 / 90 / 0 / -45 / 0 / +45; the thickened layers of the inner and outer skin corresponding to the shaped honeycomb are in an interlaced thickening form.

[0013] Preferably, the laminated sandwich structure is placed in an autoclave for curing, and the curing parameters are as follows: The temperature is maintained at 180±5℃ for 120~150min, with an average heating rate of 0.5~2℃ / min, a maximum cooling rate of 2℃ / min, and a pressure of 0.2~1.0MPa.

[0014] According to the present invention, a large-size composite material fairing integral molding device is provided, which is used to integrally mold the large-size composite material fairing.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. In this invention, the prepreg honeycomb curing and shaping mold and the composite material fairing forming mold are the same mold. After the honeycomb core material is cured and shaped, it is highly matched with the shape of the fairing. This can effectively solve the problem of uneven honeycomb pressure transmission on the skin caused by the mismatch of the surface caused by the manufacturing errors of different molds.

[0016] 2. This invention combines co-curing molding technology, which significantly reduces the number of mechanical connections of screws and pins between segmented covers. While ensuring structural strength and rigidity, it greatly improves manufacturing efficiency and significantly reduces the number of mechanical connections, resulting in obvious advantages in weight reduction. At the same time, the reduction in the number of molds and curing times will also significantly reduce production costs and shorten the manufacturing cycle.

[0017] 3. The integral molded fairing involved in this invention has a maximum diameter of 3.8m and a total length of nearly 8m. To date, there have been no public reports on the use of co-curing molding technology for composite material fairings of this size. This invention can effectively solve the problem of difficult molding of large-sized, complex-shaped composite material fairings with high wave transmission requirements and diameters of 4m and above. Attached Figure Description

[0018] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the fairing structure in an embodiment of the present invention; Figure 2 This is a schematic diagram of the cross-section of the fairing in an embodiment of the present invention.

[0019] The diagram shows: Ball head 1; Conical segment 2; Column-cone transition region 3; Column segment 4; 5. Circumferential area of ​​the cover; Fairing female mold 6; Outer skin 7; Outer film 8; Honeycomb 9 after shaping; Inner membrane 10; Inner skin 11. Detailed Implementation

[0020] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0021] Example 1: This invention provides a method for integral molding of a large-size composite material fairing, referring to... Figure 1 As shown, the fairing structure includes a ball head 1, a conical segment 2, and a cylindrical segment 4, with an overall shell-like shape. The ball head 1, conical segment 2, and cylindrical segment 4 all employ a composite honeycomb sandwich structure. This composite honeycomb sandwich structure includes, from the outside to the inside, an outer skin 7, an outer membrane 8, a shaped honeycomb 9, an inner membrane 10, and an inner skin 11. The inner skin 11 and outer skin 7 are both made of glass fiber and / or cyanate ester resin, while the shaped honeycomb 9 is made of aramid paper honeycomb. The large-size composite fairing is integrally formed by combining the ball head 1, conical segment 2, and cylindrical segment 4 into a single molding process with the composite sandwich structure co-curing. After the two fairing pieces are formed, they are assembled by interlocking metal connecting struts and frames to complete the fairing assembly. This results in a composite fairing with large size, complex curved surfaces, and certain wave-transmitting performance. Specifically, the process includes the following steps: Step S1: Manufacture a fairing molding die, the die being used for curing and shaping the honeycomb core material and molding the composite material fairing; Step S2: Cut the pre-impregnated honeycomb and lay it sequentially on the mold surface for curing and shaping. The cured and shaped honeycomb 9 serves as the core part of the composite material fairing. Place the honeycomb core material, which has been fixed on the mold, into a curing oven or autoclave for curing. The curing parameters are: 160℃±5℃, hold for 3~4h, average heating rate 0.5~1.2℃ / min, vacuum pressure ≤-0.05MPa.

[0022] Step S3: Process the height of part of the shaped honeycomb 9; process the core height of part of the shaped honeycomb 9, the processed part of the shaped honeycomb 9 includes the column-cone transition area 3 and the cover circumferential area 5.

[0023] Step S4: Lay the outer skin 7 on the mold surface. The layup process is performed with pre-compression as required. After the outer skin 7 is laid, apply a layer of adhesive film to the surface. The 0° layup direction of the inner skin 11 and the outer skin 7 is consistent with the warp direction of the prepreg. The layup angle sequence is +45 / 0 / -45 / 0 / 90 / 0 / -45 / 0 / +45. The thickened layup of the inner skin 11 and the outer skin 7 corresponding to the honeycomb 9 after shaping is in the form of interlaced thickening. Step S5: Lay the shaped honeycomb 9 onto the surface of the outer skin 7 in sequence, and continue to lay a layer of adhesive film on the inner surface of the honeycomb core material; Step S6: Continue to lay the inner skin 11 on the surface of the already laid honeycomb core material. The pre-compression operation is performed as required during the laying process. After the laying is completed, it is cured according to the co-curing molding technology. The column-cone transition area 3 and the circumferential area of ​​the cover body 5 are still thickened and laid in the same way as described in step S4. During the laying process, a pre-compression operation is performed once every 4 to 6 layers. After the laying is completed, it is placed in a thermostatic jar for curing.

[0024] The present invention also provides a large-size composite material fairing integral molding device, which is integrally molded using a large-size composite material fairing integral molding method.

[0025] Example 2: This embodiment is a preferred example of Embodiment 1, providing a method for integral molding of a large-size composite material fairing, specifically including the following steps: S1. Mold Manufacturing: Manufacture a composite material fairing female mold 6. The mold can be used for curing and shaping the honeycomb core material and forming the composite material fairing. Since the honeycomb shaping mold and the fairing forming mold are the same mold, it can be ensured that the honeycomb surface and the fairing mold surface can be completely matched after shaping. The fairing female mold 6 includes a spherical surface, a conical surface and a cylindrical surface, which match the shape of the composite material fairing. Screw holes and pin holes need to be provided in the area around the surface for installing the surround strip.

[0026] S2. Pre-impregnated honeycomb curing and shaping: The cut pre-impregnated honeycomb is laid sequentially on the mold surface, and adjacent honeycombs are sewn together with glass fiber yarn to ensure a good interlocking relationship between adjacent honeycombs after curing; the honeycomb edge needs to be provided with blank machining allowance so that the honeycomb core size matches the composite material fairing size; the surrounding strips are assembled sequentially onto the mold surface, with the honeycomb height equal to the surrounding strip height. During the curing process, the surrounding strips can fix the honeycomb and restrict the resin flow during curing, which can effectively ensure the forming quality of the honeycomb edge; the honeycomb core material fixed on the mold is placed in a curing oven or autoclave for curing; the curing parameters are: 160℃±5℃, heat preservation for 3~4h, average heating rate 0.5~1.2℃ / min, vacuum pressure ≤-0.04MPa; after curing and shaping, the honeycomb and the mold surface are height matched, serving as the core part of the composite material fairing, ensuring that the formed fairing has stable dimensions, does not debond, and does not bulge.

[0027] S3. Honeycomb Processing: Processing the height dimensions of a portion of the honeycomb core after curing and shaping. See also... Figure 1 The processed honeycomb mainly involves the column-cone transition region 3 and the circumferential region 5 of the cover. After processing, the height of the honeycomb in the column-cone transition region 3 is reduced from 28mm to 26mm, and the width of the column-cone transition region 3 is 500-600mm. For a schematic diagram of the processed honeycomb in the circumferential region 5 of the cover, please refer to [link to schematic diagram]. Figure 2Its ends are machined to have an inclination angle of 22 to 25 degrees.

[0028] S4. Lay the outer skin 7 on the mold surface. The 0° direction of the outer skin 7 should be consistent with the radial direction of the prepreg. The layering sequence is: +45 / 0 / -45 / 0 / 90 / 0 / -45 / 0 / +45. Among them, the column-cone transition area 3 and the circumferential area of ​​the cover 5 need to be interleaved and thickened. The total number of thickened layers is equal to the height difference before and after the honeycomb processing. Interleaved and thickened layers can significantly improve the mechanical properties and reliability of the part by optimizing the interlayer bonding force, stress distribution and process controllability. A pre-compression operation is required after every 4 to 6 layers are laid. After all the outer skin 7 is laid, a layer of adhesive film is applied to the surface.

[0029] S5. Lay the cured and shaped honeycomb core material sequentially onto the surface of the outer skin 7, and continue to lay a layer of adhesive film on the inner surface of the honeycomb core material. The following principle should be followed when laying the honeycomb: the staggered distance between adjacent honeycomb seams should be greater than 500mm to avoid stress concentration.

[0030] S6. Continue to lay the inner skin 11 on the surface of the already laid honeycomb core material. The 0° direction of the inner skin 11 is consistent with the warp direction of the prepreg, and the laying sequence is +45 / 0 / -45 / 0 / 90 / 0 / -45 / 0 / +45. The column-cone transition area 3 and the circumferential area 5 of the cover body are still thickened. Since the honeycomb ends of the entire circumferential area 5 of the cover body are processed at an inclination angle of 22 to 25 degrees, the inner skin 11 is interlaced and thickened in the corresponding honeycomb processing area, so that the inner skin 11 can be completely attached to the outer skin 7 along the honeycomb slope. This ensures that the edge stiffness of the cover meets the overall assembly requirements, and can be used for subsequent installation of metal docking trusses and docking frames to complete the cover assembly. During the inner skin 11 layup process, a pre-compression operation is performed every 4-6 layers. After layup, breathable material is laid on the surface of the inner skin 11, and a vacuum bag is formed as a whole, then placed in an autoclave for curing. Curing parameters: 180±5℃ for 120-150 min, average heating rate 0.5-2℃ / min, maximum cooling rate 2℃ / min, pressure 0.2-1.0 MPa. After curing, the vacuum bag and breathable material are removed, and the composite material fairing is obtained after demolding.

[0031] It should be noted that the above technical solution is a molding method for a single composite material hood. Another composite material hood is made according to the same technical solution. The two hoods are then assembled by connecting them with metal connecting trusses and connecting frames to complete the hood, thereby obtaining a composite material fairing with large size, complex curved surface and other shape characteristics and certain wave transmission performance.

[0032] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0033] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for integral molding of a large-size composite material fairing, characterized in that, Includes the following steps: Step S1: Manufacture a fairing molding die, the die being used for curing and shaping the honeycomb core material and molding the composite material fairing; Step S2: Cut the pre-impregnated honeycomb and lay it on the mold surface in sequence for curing and shaping. The shaped honeycomb (9) after curing and shaping serves as the core part of the composite material fairing. Adjacent honeycombs are sewn together with glass fiber yarn. The surrounding strips are assembled onto the mold surface in sequence. The height of the honeycomb is equal to the height of the surrounding strips. Step S3: The height of the partially shaped honeycomb (9) is processed. The partially shaped honeycomb (9) includes a column-cone transition area (3) and a cover circumferential area (5). The height of the column-cone transition area (3) can be reduced by 2mm after honeycomb processing. The width of the column-cone transition area (3) is 500-600mm. The end of the cover circumferential area (5) is processed to an inclination angle of 22-25° after honeycomb processing. The column-cone transition area (3) and the cover circumferential area (5) need to be interlaced with thickened ply. The total number of thickened ply is equal to the height difference before and after honeycomb processing. The interlaced thickened ply can improve the mechanical properties and reliability of the part by optimizing the interlayer bonding force, stress distribution and process controllability. Step S4: Lay the outer skin (7) on the mold surface. The pre-compression operation is performed as required during the laying process. After the outer skin (7) is laid, a layer of adhesive film is attached to the surface. Step S5: The shaped honeycomb (9) is laid sequentially onto the surface of the outer skin (7), and a layer of adhesive film is then laid on the inner surface of the honeycomb core material; Step S6: Continue to lay the inner skin (11) on the surface of the already laid honeycomb core material. The pre-compression operation is performed as required during the laying process. After the laying is completed, the co-curing molding technology is used for curing.

2. The method for integral molding of a large-size composite material fairing according to claim 1, characterized in that, The fairing structure includes a ball head (1), a cone section (2), and a column section (4), all of which adopt a composite material honeycomb sandwich structure.

3. The method for integral molding of a large-size composite material fairing according to claim 2, characterized in that, The composite honeycomb sandwich structure includes an outer skin (7), an outer adhesive film (8), a shaped honeycomb (9), an inner adhesive film (10), and an inner skin (11) arranged sequentially from the outside to the inside.

4. The method for integral molding of a large-size composite material fairing according to claim 3, characterized in that, The inner skin (11) and outer skin (7) are both made of glass fiber and / or cyanate ester resin material system, and the shaped honeycomb (9) is made of aramid paper honeycomb.

5. The method for integral molding of a large-size composite material fairing according to claim 1, characterized in that, The method involves integral molding of the ball head (1), cone segment (2) and column segment (4) combined with the co-curing of composite material sandwich structure. After the two covers are formed, they are assembled by interlocking metal trusses and interlocking frames to obtain the composite material fairing.

6. The method for integral molding of a large-size composite material fairing according to claim 1, characterized in that, In step S2, the honeycomb core material, which has been fixed on the mold, is placed in a curing oven or autoclave for curing; the curing parameters are as follows: 160℃±5℃, hold for 3~4h, average heating rate 0.5~1.2℃ / min, vacuum pressure ≤-0.05MPa.

7. The method for integral molding of a large-size composite material fairing according to claim 3, characterized in that, The inner skin (11) and outer skin (7) are laid in the same direction at 0° as the prepreg warp direction, and the layup angle sequence is +45 / 0 / -45 / 0 / 90 / 0 / -45 / 0 / +45; the thickened layup of the inner skin (11) and outer skin (7) corresponding to the shaped honeycomb (9) is in the form of interlaced thickening.

8. The method for integral molding of a large-size composite material fairing according to claim 3, characterized in that, The laminated sandwich structure was then placed in an autoclave for curing. The curing parameters were as follows: The temperature is maintained at 180±5℃ for 120~150min, with an average heating rate of 0.5~2℃ / min, a maximum cooling rate of 2℃ / min, and a pressure of 0.2~1.0MPa.

9. A large-size composite material fairing integral molding device, which is integrally molded using the large-size composite material fairing integral molding method according to any one of claims 1 to 8.

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