Mould for forming a composite satellite fairing

Abstract

This invention provides a molding die for a composite satellite fairing, comprising: a main female mold (1), a front support base (2), and a rear support base (3); the main female mold (1) includes a molding curved template (4), a porous reinforcing rib plate (5), base mounting feet (6), and a back venting structure (7). This invention enables uniform heating of the double-curvature structure, thereby reducing curing deformation and improving the appearance molding quality. This invention designs the size of the vent holes in the back reinforcing ribs of the large-size fairing mold through iterative analysis of the thermal flow field. As the distance in the heat flow direction increases, the cross-sectional area of ​​the vent holes gradually decreases, allowing more heat flow to accumulate in the mold's location away from the heat source, reducing the temperature gradient on the back of the mold in the heat flow direction, resulting in a uniform mold surface temperature and reduced curing deformation.

Description

Technical Field

[0001] This invention belongs to the field of resin-based composite material molding technology, specifically relating to molding dies for composite satellite fairings. More particularly, it relates to a molding die for a low-curing-deformation composite satellite fairing. Background Technology

[0002] The fairing is a crucial component of a launch vehicle, protecting satellites or other payloads from the harmful effects of aerodynamic forces, aerodynamic heating, and acoustic vibrations. The fairing structure often utilizes the von Kármán curve shape to better reduce air resistance and mitigate load impacts. Compared to other sections of the launch vehicle, satellite fairings are characterized by their large diameter, long length, and high assembly precision requirements. Furthermore, because the von Kármán curve is a non-linear curve, its unfolded structure is not planar, making manufacturing more challenging.

[0003] For example, patent document CN115847671A discloses a mold and processing method for forming a large fairing, including multiple support points on the bottom of the main mold, a transfer support plate on the bottom of the main mold, and lifting rods on the outer periphery of the main mold; a surrounding strip is fixed to the inner wall of the main mold along the outer contour of the product; a window core mold is fastened to the inner wall of the main mold; a silicone rubber ring is sleeved on the window core mold; multiple air nozzles are evenly distributed on the periphery of the main mold; a demolding insert is installed on the demolding side of the main mold in the flight direction; the demolding assembly and the demolding insert are detachably connected; the demolding assembly demolds the product in the flight direction.

[0004] For example, patent document CN115816718A provides a method for preparing an integral mold for a large fairing von Kármán section, which relates to the field of fairing mold design. The specific steps are as follows: S1, determine the angle of the female mold so that the bottom generatrix is ​​approximately flat to lower the center of gravity of the overall mold; S2, optimize the structural form and layout of the reinforcing ribs of the female mold; S3, the bottom of the female mold is provided with a fixed three-point support; S4, fixed lifting points are provided on both sides of the frame, and detachable air extraction nozzles and detachable air extraction adapters are provided on the frame; S5, the female mold surface is provided with co-curing strips, post-bonding strips, positioning pins and screws, and placeholder blocks to meet the requirements of co-curing and post-bonding; S6, pressure is applied above the sandwich structure using a pressure equalizing plate to finally form the integral mold.

[0005] Currently, with the development of China's aerospace industry, rocket fairings are increasingly being manufactured using composite materials. The von Kármán curve-shaped fairing cones have a hyperbolic structure and often employ a honeycomb sandwich structure, formed using autoclave technology. Generally, to ensure aerodynamic shape, the outer surface of the fairing is used as the coating surface. However, due to its large size and complex structure, it is prone to uneven heating during curing. The internal thermal stress can cause deformation at the joints, hindering subsequent assembly. Furthermore, the coating surface is prone to air trapping, resulting in pores or localized adhesive defects. Summary of the Invention

[0006] In view of the deficiencies in the prior art, the purpose of this invention is to provide a molding die for a composite material satellite fairing.

[0007] A molding die for a composite satellite fairing according to the present invention includes: a main body female mold 1, a front support base 2, and a rear support base 3; The front and rear base mounting feet 6 at the bottom of the main body female mold 1 are respectively supported by the front support base 2 and the rear support base 3; The different heights of the front support base 2 and the rear support base 3 raise the main body female mold 1, so as to form the angle of the surface of the molding mold relative to the heat flow direction of the autoclave. The heat flow field simulation and the actual measured temperature rise characteristics of the mold are obtained by matching the temperature measuring points set on the molding curved template 4 of the main body female mold 1.

[0008] Preferably, the main female mold 1 includes: a porous reinforcing rib plate 5; The porous reinforcing rib plate 5 has ventilation holes. Along the direction of heat flow, the cross-sectional area of ​​the ventilation holes on the porous reinforcing rib plate 5 is reduced, so that the molding die can obtain more heat flow accumulation away from the heat source.

[0009] Preferably, the porous reinforcing rib plate 5 includes multiple cross-welded transverse rib plates and multiple longitudinal rib plates, with annular rib plates arranged between every two transverse rib plates to enhance the overall rigidity of the mold.

[0010] Preferably, the main female mold 1 includes: a back air extraction structure 7; The back air extraction structure 7 is set at the weld junction of the forming curved template 4 of the main female mold 1; Air guide pins 8 are provided on the forming curved template 4 of the main female mold 1; An annular gap is left between the forming curved template 4 and the air guide pin 8; The back-side air extraction structure 7 connects with the mold surface through an annular gap to achieve airflow and perform back-side air extraction of the part.

[0011] Preferably, the back-side air extraction structure 7 is provided with an air nozzle 12 connected to an external vacuum pump to achieve back-side air extraction.

[0012] Preferably, cylindrical positioning pins 13 and stepped positioning pins 14 are provided on the forming curved surface template 4 of the main body female mold 1, respectively located on the upper and lower end faces of the fairing, to provide positioning for the adhesive assembly after the fairing outer skin has been cured; The stepped positioning pin 14 has a gap between its long side and the outer skin of the fairing, allowing the outer skin to slide freely when heated during the co-bonding process of the fairing.

[0013] Preferably, the base support feet 6 of the main female mold 1 are three in number and are set at the intersection of the reinforcing ribs. These three points are used as support points during mold processing and use to ensure that the processing and use conditions are the same and the deformation is consistent.

[0014] According to the present invention, a satellite fairing is prepared by means of a molding die for the composite material satellite fairing.

[0015] Preferably, during the preparation process, when the part is cured, a vacuum bag is made on the upper surface of the part, and an air extraction nozzle is placed there. The vacuum is simultaneously drawn with the back air extraction structure 7 to avoid local air entrapment.

[0016] According to the present invention, a method for preparing a satellite fairing includes using a molding die for the composite material satellite fairing; during the curing of the part, a vacuum bag is made on the upper surface of the part, and an air extraction nozzle is placed thereto, and a vacuum is simultaneously drawn with the back air extraction structure 7 to avoid local air entrapment.

[0017] The beneficial effects of this invention compared to the prior art are: 1. The present invention can achieve uniform heating of the hyperbolic structure, thereby reducing the curing deformation of the part and improving the appearance molding quality.

[0018] 2. This invention designs the size of the vent holes of the reinforcing ribs on the back of the large-sized mold of the fairing through iterative analysis of the thermal flow field. As the distance in the thermal flow direction increases, the cross-sectional area of ​​the vent holes gradually decreases, and the mold obtains more heat flow accumulation at the position away from the heat source, thereby reducing the temperature gradient on the back of the mold in the thermal flow direction.

[0019] 3. This invention combines thermal flow field simulation and mold heating characteristic test to reasonably design the height of the front and rear mounting bases, so that the surface temperature of the mold is uniform and consistent, which together ensures that the part is heated evenly, reduces curing deformation, and the deformation of the single side of the rectifier after molding does not exceed 3mm, which is conducive to subsequent assembly.

[0020] 4. This invention, through the back-side air extraction structure of the main body mold, avoids air stagnation on the film-coated surface of large-sized parts, resulting in a fairing with excellent surface quality after molding, free from pinholes or localized glue defects. Simultaneously, air is extracted from both the upper and lower surfaces of the part, ensuring the quality of both the inner and outer surfaces. Attached Figure Description

[0021] 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 showing the comparison between the side view of the molding die, the exploded view of the main female mold, and the isometric view of the molding die of the present invention.

[0022] Figure 2 This is a schematic diagram comparing the cross-sectional and axonometric views of the back air extraction structure of the molding die of the present invention.

[0023] Figure 3 This is a schematic diagram of the positioning pin of the present invention.

[0024] The diagram shows: Detailed Implementation

[0025] 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.

[0026] This invention relates to a molding die for a low-curing-deformation composite satellite fairing. The molding die is used for molding the honeycomb sandwich structure of the conical section of the fairing with a von Kármán curve shape. Through simulation, the size and layout of the reinforcing ribs and vents on them are rationally designed. The angle of the mold relative to the heat flow is adjusted by the bottom support base, effectively controlling the heat flow on the product surface and the film-coated surface, ensuring uniform heating. The deformation of the molded product at one side does not exceed 3mm, meeting subsequent assembly requirements. Simultaneously, the main female mold has a back-side air extraction structure, preventing air trapping on the film-coated surface of large-sized parts. The molded fairing has good surface quality, without pinholes or localized glue defects.

[0027] like Figure 1 As shown, the present invention proposes a molding die for a satellite fairing made of low-curing-deformation composite material, including a main body female mold 1, a front support base 2, and a rear support base 3. The main body female mold 1 is placed on the front support base 2 and the rear support base 3.

[0028] The main female mold 1 includes a forming curved template 4, a porous reinforcing rib plate 5, a base mounting feet 6, and a back air extraction structure 7. The layout, height, and thickness of the porous reinforcing rib plate are determined using structural mechanics simulation; the size of the vent holes and the height of the front and rear support seats are adjusted using thermal flow field iterative analysis to ensure uniform temperature on the forming surface of the mold.

[0029] The porous reinforcing rib 5 has vents. As the distance in the heat flow direction increases, the cross-sectional area of ​​the vents decreases, allowing the molding die to accumulate more heat away from the heat source. The cross-sectional area of ​​the vents in the mold reinforcing rib along the heat flow direction increases from 1.3 m². 2 Reduced to 0.28m each time. 2 .

[0030] Front and rear support bases are installed on the base mounting feet 6 of the main female mold 1 to adjust the angle of the mold surface relative to the heat flow direction of the autoclave. Temperature measuring points are set on the forming curved template 4 of the forming mold. The height of the front support base 2 and / or the rear support base 3 is adjusted according to the thermal flow field simulation and the actual measured temperature rise characteristics of the mold. The height of the front support base 2 is determined to be 560mm, the height of the rear support base 3 is determined to be 185mm, and the small end of the forming mold is raised by 10° to reduce the temperature difference between different areas of the surface during the curing process.

[0031] The main body female mold 1 has three base support feet 6, which are set at the intersection of the reinforcing ribs. These three points are used as support points during mold processing and use to ensure that the processing and use conditions are the same and the deformation is consistent.

[0032] The forming mold was mechanically designed using finite element analysis, optimizing the layout, height, thickness, and position of the base mounting feet 6 of the perforated reinforcing rib plate 5. The perforated reinforcing rib plate 5 is 12mm thick and consists of 6 horizontal rib plates and 9 vertical rib plates welded together. Between every two horizontal rib plates, a small annular rib plate with a thickness of 8mm and a height of 80mm is arranged to enhance the overall rigidity of the mold.

[0033] like Figure 1 As shown, the back-side air extraction structure 7 of the main female mold 1 is located at the weld junction of the forming curved template 4. Figure 2 As shown, a 0.3mm-1mm wide annular gap is left between the forming curved template 4 and the air guide pin 8. The back air extraction structure 7 connects with the mold surface through the annular gap to achieve airflow. A sealing groove is set on the flange of the back air extraction structure 7 and a high-temperature resistant sealing ring 9 is placed inside. The outer flange cover plate 10 is locked and sealed by a butterfly nut 11. An air nozzle 12 is set on the back air extraction structure 7 and connected to an external vacuum pump to achieve back air extraction. During the curing process of the part, a vacuum bag is placed on the upper surface and an air extraction nozzle is placed there. Vacuuming is carried out simultaneously with the back air extraction structure 7 to avoid local air entrapment and improve the surface forming quality of the part.

[0034] like Figure 3 As shown, cylindrical positioning pins 13 and stepped positioning pins 14 are set on the molded curved template 4, located on the upper and lower end faces of the fairing respectively, to cooperate with the step-by-step curing process of the fairing outer skin, honeycomb and fairing body, to realize the adhesive assembly positioning of the fairing outer skin after curing; the stepped positioning pin 14 maintains a 3mm gap with the fairing outer skin on one side of its long side to ensure that the outer skin can slide freely when heated during the fairing co-bonding process.

[0035] 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.

[0036] 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 molding die for a composite material satellite fairing, characterized in that, include: Main body female mold (1), front support base (2), rear support base (3); The front and rear base mounting feet (6) at the bottom of the main body female mold (1) are respectively supported by the front support base (2) and the rear support base (3); The different heights of the front support base (2) and the rear support base (3) raise the main body female mold (1) to form the angle of the surface of the molding mold relative to the heat flow direction of the autoclave. The heat flow field simulation and the actual temperature rise characteristics of the mold are obtained by matching the temperature measuring points set on the molding curved template (4) of the main body female mold (1).

2. The molding die for the composite satellite fairing according to claim 1, characterized in that, The main female mold (1) includes: a porous reinforcing rib plate (5); The porous reinforcing rib plate (5) has ventilation holes. Along the direction of heat flow, the cross-sectional area of ​​the ventilation holes on the porous reinforcing rib plate (5) is reduced, so that the molding die can obtain more heat flow accumulation away from the heat source.

3. The molding die for the composite satellite fairing according to claim 2, characterized in that, The perforated reinforcing rib (5) includes multiple cross-welded transverse ribs and multiple longitudinal ribs, with annular ribs arranged between every two transverse ribs to enhance the overall rigidity of the mold.

4. The molding die for the composite satellite fairing according to claim 1, characterized in that, The main female mold (1) includes: a back air extraction structure (7); The back air extraction structure (7) is set at the weld joint position of the forming curved template (4) of the main body female mold (1); Air guide pins (8) are provided on the forming curved template (4) of the main female mold (1); An annular gap is left between the forming curved template (4) and the air guide pin (8); The back-side air extraction structure (7) connects the airflow with the mold surface through an annular gap to perform back-side air extraction of the part.

5. The molding die for the composite satellite fairing according to claim 4, characterized in that, An air nozzle (12) is installed on the back air extraction structure (7) and connected to an external vacuum pump to achieve back air extraction.

6. The molding die for the composite satellite fairing according to claim 1, characterized in that, The main body female mold (1) is provided with cylindrical positioning pins (13) and stepped positioning pins (14) on the forming curved surface template (4), which are located on the upper and lower end faces of the fairing respectively, to provide positioning for the adhesive assembly after the fairing outer skin is cured; The stepped positioning pin (14) has a gap between its long side and the outer skin of the fairing, allowing the outer skin to slide freely when heated during the co-bonding process of the fairing.

7. The molding die for the composite satellite fairing according to claim 1, characterized in that, The base support feet (6) of the main female mold (1) are three in number and are set at the intersection of the reinforcing ribs. These three points are used as support points during mold processing and use to ensure that the processing and use conditions are the same and the deformation is consistent.

8. A satellite fairing, characterized in that, It is prepared by molding a composite satellite fairing according to any one of claims 1 to 7.

9. The satellite fairing according to claim 8, characterized in that, During the preparation process, when the part is cured, a vacuum bag is made on the upper surface of the part and an air extraction nozzle is placed there. The vacuum is simultaneously drawn with the back air extraction structure (7) to avoid local air stagnation.

10. A method for manufacturing a satellite fairing, characterized in that, The mold includes a composite material satellite fairing mold according to any one of claims 1 to 7; when the part is cured, a vacuum bag is made on the upper surface of the part, and an air extraction nozzle is placed thereto, and vacuum is drawn at the same time as the back air extraction structure (7) to avoid local air stagnation.

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