Die and forming method of cylindrical composite material structure

Abstract

The invention provides a mold of a cylindrical composite material structure and a forming method, and relates to the technical field of bearing structures on spacecrafts, the mold of the cylindrical composite material structure comprises a plurality of single-layer mold units, and the single-layer mold units are detachably stacked and assembled in the axial direction; each single-layer mold unit is provided with a forming surface used for paving prepreg to form a reinforcing rib, and each single-layer mold unit is of a split type structure, so that after the cylindrical composite material structure is cured and formed, the single-layer mold units are disassembled to be taken out from the cylindrical composite material structure. The invention provides a mold and a forming method of a cylindrical composite material structure. The cylindrical composite material structure with continuous reinforcing ribs and outer skin fibers is formed.

Description

Technical Field

[0001] This application relates to the field of spacecraft load-bearing structure technology, and in particular to a mold and molding method for a cylindrical composite material structure. Background Technology

[0002] Carbon fiber composites are widely used in the aerospace field due to their excellent specific stiffness. In existing technologies, to enhance the stability of cylindrical composite structures, interlocking or annular reinforcing ribs are added to the inner wall of the product to improve its structural rigidity.

[0003] Currently, there are two commonly used methods. One is to mold the skin structure and reinforcing rib structure separately and then bond them together using adhesive. The other is to lay the reinforcing ribs in the mold groove and then lay the skin. However, neither method can guarantee the continuity of the reinforcing ribs and skin fibers, and the load-bearing strength of the reinforcing ribs is not high. Summary of the Invention

[0004] The purpose of this application is to address the above problems by providing a mold and molding method for a cylindrical composite material structure, so as to form a cylindrical composite material structure with continuous reinforcing ribs and outer skin fibers.

[0005] In a first aspect, this application provides a mold for a cylindrical composite material structure, comprising: a plurality of single-layer mold units, wherein the plurality of single-layer mold units are detachably stacked and assembled along the axial direction, each single-layer mold unit having a molding surface for laying prepreg to form reinforcing ribs, and each single-layer mold unit being a split structure, so that after the cylindrical composite material structure is cured and molded, the single-layer mold units can be disassembled to be removed from the cylindrical composite material structure.

[0006] According to the technical solutions provided in certain embodiments of this application, the single-layer mold unit includes: a central fixed disk, which is a circular disk, and the lower surface of the central fixed disk has a mating groove around the center; and a plurality of movable blocks, which are fan-shaped plates, and the upper surface of the movable blocks has a mating block. The plurality of movable blocks are arranged around the circumference of the central fixed disk, and the mating block on the upper surface of the movable block is inserted into the mating groove on the lower surface of the central fixed disk.

[0007] According to the technical solutions provided in certain embodiments of this application, the arc edges of the upper surface and the arc edges of the lower surface of the movable block are provided with laying grooves. The laying grooves of multiple movable blocks in the same single-layer mold unit are connected to form an annular groove. The prepreg can be cured at the annular groove to form the reinforcing rib.

[0008] According to the technical solutions provided in certain embodiments of this application, the single-layer mold unit includes at least four sequentially connected movable blocks. The at least four movable blocks include a plurality of first movable blocks and a plurality of second movable blocks. Each of the first movable blocks and each of the second movable blocks of the single-layer mold unit is alternately arranged around the outer circumference of the central fixed disk. The inner arc length of the first movable block is less than the outer arc length, and the inner arc length of the second movable block is greater than the outer arc length.

[0009] According to the technical solutions provided in certain embodiments of this application, two adjacent single-layer mold units are positioned and stacked in the axial direction by means of positioning pins and positioning holes.

[0010] According to the technical solutions provided in some embodiments of this application, the depth of the paving groove is greater than 5mm.

[0011] According to the technical solutions provided in certain embodiments of this application, the cross-section of the reinforcing rib of the cylindrical composite material structure is C-shaped with the opening facing the axis of the cylindrical composite material structure. The cross-sectional height of the reinforcing rib is greater than its cross-sectional width, and its open end is connected to the outer skin, while its closed end faces the inside of the cylinder.

[0012] Secondly, the molding method provided in this application is applicable to the mold described in any of the first aspects above. The molding method includes: assembling multiple movable blocks on a central fixed plate to form a single-layer mold unit, and applying prepreg to the outer peripheral surface and the application groove of the movable blocks; stacking and assembling multiple single-layer mold units with the prepreg applied to form a mold with a cylindrical composite material structure; applying an outer skin to the outer peripheral surface of the mold; and placing the mold with the skin applied in an autoclave for process curing to form a cylindrical composite material structure with reinforcing ribs on the inner surface.

[0013] According to the technical solutions provided in some embodiments of this application, the method further includes: after disassembling the movable block from the central fixing plate, taking it out sequentially from the formed cylindrical composite material structure to demold and obtain the cylindrical composite material structure with reinforcing ribs.

[0014] Compared with existing technologies, the beneficial effects of this application are as follows: According to the mold for a cylindrical composite material structure, the modular and detachable mold design allows for independent and precise application of prepreg on the molding surface of each single-layer mold unit, creating conditions for the continuous placement of reinforcing fiber. After the outer skin is applied and co-cured, its modular structure allows the mold to be easily removed from the cured integrally molded product, thus completely solving the demolding problem caused by the reinforcing ribs. Therefore, it not only improves the fiber continuity between the reinforcing ribs and the outer skin to enhance the structural load-bearing capacity, but also achieves the dual benefits of feasible demolding of complex structures to ensure both process feasibility and product integrity.

[0015] It should be understood that the descriptions of technical features, technical solutions, beneficial effects, or similar language in this application do not imply that all features and advantages can be achieved in any single embodiment. Rather, it is understood that the description of a feature or beneficial effect means that a specific technical feature, technical solution, or beneficial effect is included in at least one embodiment. Therefore, the descriptions of technical features, technical solutions, or beneficial effects in this specification do not necessarily refer to the same embodiment. Furthermore, the technical features, technical solutions, and beneficial effects described in this embodiment can be combined in any suitable manner. Those skilled in the art will understand that embodiments can be implemented without one or more specific technical features, technical solutions, or beneficial effects of a particular embodiment. In other embodiments, additional technical features and beneficial effects may be identified in specific embodiments that do not embody all embodiments. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A three-dimensional structural diagram of a mold with a cylindrical composite material structure provided in this application embodiment; Figure 2 A side view of a mold for a cylindrical composite material structure provided in an embodiment of this application; Figure 3 for Figure 2 Enlarged view of a portion of point A in the middle; Figure 4 A top view of a mold for a cylindrical composite material structure provided in an embodiment of this application; Figure 5 This is a three-dimensional structural diagram of a mold for a cylindrical composite material structure provided in an embodiment of this application, which hides the middle fixing plate of the upper layer; Figure 6 A three-dimensional structural diagram of the central fixing plate of a cylindrical composite material mold provided in an embodiment of this application; Figure 7 A longitudinal cross-sectional view of a cylindrical composite material structure provided in an embodiment of this application; Figure 8 This is a flowchart illustrating the steps of the molding method for the cylindrical composite material structure of this application.

[0018] The text labels in the image represent: 1. Single-layer mold unit; 2. Central fixing plate; 21. Mating groove; 3. Loose block; 31. Matching block; 32. Laying groove; 4. Outer skin; 5. Reinforcing ribs. Detailed Implementation

[0019] To enable those skilled in the art to better understand the technical solutions of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. The descriptions in this section are merely illustrative and explanatory, and should not be construed as limiting the scope of protection of this application. Specifically, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort should fall within the scope of protection of this application.

[0020] It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product, or apparatus.

[0021] As mentioned in the background section, carbon fiber composites are widely used in the aerospace field due to their excellent specific stiffness. In existing technologies, to enhance the stability of composite cylindrical structures, interlaced or annular reinforcing ribs are added to the inner wall of the product to improve its structural rigidity.

[0022] Currently, there are two commonly used methods. One is to mold the skin structure and reinforcing rib structure separately and then bond them together using adhesive. The other is to lay the reinforcing ribs in the mold groove and then lay the skin. However, neither method can guarantee the continuity of the reinforcing ribs and skin fibers, and the load-bearing strength of the reinforcing ribs is not high.

[0023] To address the problems in the prior art, this embodiment provides a mold and molding method for a cylindrical composite material structure. The following description, in conjunction with the appendix, details the process. Figures 1-7 The mold for the cylindrical composite material structure of this application is described in detail.

[0024] like Figure 1As shown, the mold for the cylindrical composite material structure includes multiple single-layer mold units 1, which are detachably stacked and assembled along the axial direction. Each single-layer mold unit 1 has a molding surface for laying prepreg to form reinforcing ribs 5, and each single-layer mold unit is a split structure so that after the cylindrical composite material structure is cured and molded, the single-layer mold unit can be disassembled to remove it from the cylindrical composite material structure.

[0025] Specifically, such as Figure 1 As shown, after the cylindrical composite material structure is cured and molded, it can be easily removed from the cylindrical composite material structure by disassembling the single-layer mold unit 1. This effectively solves the problem of traditional one-piece molds being unable to demold due to the complex structure of the reinforcing rib 5, ensuring product integrity and improving production efficiency. Furthermore, by individually applying prepreg to multiple single-layer mold units 1 and stacking these prepreg-coated single-layer mold units 1, a C-shaped reinforcing rib 5 can be formed after curing. Applying an outer skin to the mold after applying the prepreg ensures fiber continuity between the reinforcing rib 5 and the outer skin 4 in the cured cylindrical composite material structure, improving the overall structural strength. Moreover, the reinforcing rib 5 and the outer skin 4 are integrally cured and molded, achieving improved overall strength while maintaining a lightweight design.

[0026] According to the mold of the cylindrical composite material structure disclosed in this application, the modular and detachable mold design allows for the independent and precise laying of prepreg on the molding surface of each single-layer mold unit 1, creating conditions for the continuous laying of reinforcing rib 5 fibers. After the outer skin 4 is laid and co-cured, its modular structure allows the mold to be easily removed from the cured integrally molded product by disassembly, thus completely solving the demolding problem caused by the reinforcing rib 5. Therefore, it not only improves the fiber continuity between the reinforcing rib 5 and the outer skin 4 to enhance the structural load-bearing capacity, but also achieves the dual benefits of feasible demolding of complex structures to ensure both process feasibility and product integrity.

[0027] In some embodiments of this application, such as Figures 1-6 As shown, the single-layer mold unit 1 includes a central fixed plate 2 and multiple movable blocks 3. The central fixed plate 2 is a circular plate, and its lower surface has a mating groove 21 surrounding the center. The movable blocks 3 are fan-shaped plates, and their upper surfaces have mating blocks 31. The multiple movable blocks 3 are arranged around the circumference of the central fixed plate, and the mating blocks 31 on the upper surface of the movable blocks 3 are inserted into and engaged with the mating groove 21 on the lower surface of the central fixed plate 2.

[0028] Specifically, the interlocking structure ensures precise positioning and reliable connection between the movable block 3 and the central fixing plate 2, providing a stable foundation for subsequent laying and stacking, and preventing misalignment during the process. Furthermore, in the cured cylindrical composite material structure, the single-layer mold unit 1 can be removed by disassembling the movable block 3 and the central fixing plate 2.

[0029] In some embodiments of this application, the movable block 3 has a laying groove 32, and the laying groove 32 is formed on both the arc edge of the upper surface and the arc edge of the lower surface of the movable block 3. Multiple laying grooves 32 of multiple movable blocks 3 in the same single-layer mold unit 1 are connected to form an annular groove, and the prepreg can be cured at the annular groove to form a reinforcing rib 5.

[0030] Specifically, the mounting grooves 32 on the segmented movable blocks 3 collectively form an annular groove, ensuring the continuity and consistency of the shape of the reinforcing rib 5 and facilitating the removal of the movable blocks 3 during demolding. Furthermore, mounting grooves 32 are provided on both the upper and lower arc edges of the movable blocks 3. This allows the prepreg mounted at the corresponding positions of the mounting grooves 32 to form a unified reinforcing rib 5 after curing when two adjacent single-layer mold units 1 are stacked, thereby increasing the strength of the reinforcing rib 5. In other words, when the molds are stacked, the mounting grooves 32 on each layer of movable blocks 3 can correctly align with the structure of the adjacent layers, collectively forming a continuous cavity for molding the C-shaped reinforcing rib.

[0031] In some embodiments of this application, such as Figure 4 and Figure 5 As shown, the single-layer mold unit 1 includes at least four sequentially connected movable blocks 3. Each of the at least four movable blocks 3 includes multiple first movable blocks and multiple second movable blocks. The first movable blocks and second movable blocks of the single-layer mold unit 1 are alternately arranged around the outer circumference of the central fixed disk 2. They are cyclically connected in the order of the first and second movable blocks. The inner arc length of the first movable block is less than the outer arc length, and the inner arc length of the second movable block is greater than the outer arc length.

[0032] Specifically, such as Figure 4 As shown, the alternating arrangement of the first and second movable blocks allows all the movable blocks 3 to fit tightly together in the circumferential direction to form a complete ring, while also interlocking in the axial direction. This enhances the overall structural stability of the mold during the laying and pre-pressing process, preventing gaps or warping. Furthermore, the inner arc length of the second movable block is greater than its outer arc length. Therefore, during disassembly, the second movable block can be removed by pushing it towards the center. Removing the second movable block provides space for disassembling the first movable block, thus allowing multiple movable blocks 3 to be sequentially removed from the interior of the molded cylindrical composite material structure.

[0033] In some embodiments of this application, two adjacent single-layer mold units 1 are positioned and stacked in the axial direction by means of positioning pins and positioning holes.

[0034] Specifically, such as Figure 2 , Figure 4 and Figure 5 As shown, the positioning structure ensures the positional accuracy of each layer of reinforcing ribs 5 in the axial and radial directions, thereby guaranteeing the geometric accuracy and load-bearing reliability of the multi-layer reinforcing ribs 5 in the final product. The axial position refers to the height direction perpendicular to the horizontal plane.

[0035] In some embodiments of this application, such as Figure 3 As shown, the groove depth of the paving groove 32 is greater than 5mm.

[0036] Specifically, the depth of the laying groove 32 is greater than 5mm. Therefore, after the prepreg of two adjacent single-layer mold units 1 has cured, a reinforcing rib 5 with a thickness of not less than 10mm can be formed at the position of the laying groove 32. This not only forms a reinforcing rib 5 with sufficient cross-sectional height to provide significant rigidity enhancement, but also takes into account the process feasibility, such as the difficulty of prepreg laying, compaction, and demolding, avoiding the manufacturing difficulties caused by excessive depth or the insufficient reinforcement effect caused by excessive shallowness.

[0037] In some embodiments of this application, such as Figure 7 As shown, the cross-section of the reinforcing rib 5 of the cylindrical composite material structure is C-shaped with the opening facing the axis of the cylindrical composite material structure. The cross-sectional height of the reinforcing rib 5 is greater than its cross-sectional width, and its open end is connected to the outer skin 4, while its closed end faces the inside of the cylinder.

[0038] Specifically, the C-shaped cross-section and the design with a height greater than the width give the stiffener excellent bending stiffness in the radial direction. At the same time, its open end is connected to the large area of ​​continuous fibers of the skin, which greatly improves the tightness and structural integrity of the connection between the stiffener 5 and the outer skin 4, which is far superior to the traditional interlayer bonding.

[0039] Secondly, this application provides a molding method for a cylindrical composite material structure, the molding method being applicable to the molds described in any of the first aspects above, such as... Figure 8 As shown, the molding method includes: Step S1: Assemble multiple movable blocks 3 onto the central fixing plate 2 to form a single single-layer mold unit 1, and apply prepreg to the outer periphery of the movable block 3 and the laying groove 32; Step S2: Stack and assemble multiple single-layer mold units 1 with prepreg laid on them to form a mold with a cylindrical composite material structure; Step S3: Apply the outer skin to the outer circumference of the mold; Step S4: Place the mold for applying the skin into an autoclave for curing to form a cylindrical composite material structure with reinforcing ribs 5 on the inner surface.

[0040] Specifically, this method systematically achieves physical continuity between the prepreg forming the reinforcing rib 5 and the outer skin 4 at the fiber level through a process of first laying the prepreg in sections, then laying the outer skin 4 as a whole on the outside, and finally co-curing in a hot autoclave. This process forms an integrated structure at the molecular level, fundamentally solving the problem of weak connection between the interface of the outer skin 4 and the reinforcing rib 5.

[0041] In some embodiments of this application, it also includes: Step S5: After disassembling the movable block 3 from the central fixing plate 2, remove them sequentially from the molded cylindrical composite material structure to demold and obtain a cylindrical composite material structure with reinforcing ribs 5.

[0042] Specifically, by making full use of the mold's split design and through orderly disassembly, the complete demolding of complex-shaped products can be achieved without damaging the fragile C-shaped reinforcing rib 5 structure, thus ensuring product qualification rate and economic benefits.

[0043] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. The above descriptions are only preferred embodiments of this application. It should be noted that due to the limitations of textual expression, while there are objectively infinite specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of this application, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the concept and technical solution of the application to other occasions without modification, should all be considered within the scope of protection of this application.

Claims

1. A mold with a cylindrical composite material structure, characterized in that, include: Multiple single-layer mold units (1) are detachably stacked and assembled along the axial direction. Each single-layer mold unit (1) has a molding surface for laying prepreg to form reinforcing ribs (5). Each single-layer mold unit is a split structure so that after the cylindrical composite material structure is cured and molded, the single-layer mold unit can be disassembled to be removed from the cylindrical composite material structure.

2. The mold according to claim 1, characterized in that, The single-layer mold unit (1) includes: The central fixing disk (2) is a circular disk, and the lower surface of the central fixing disk (2) has a mating groove (21) around the center. Multiple movable blocks (3) are fan-shaped plates. The upper surface of the movable block (3) has a mating block (31). The multiple movable blocks (3) are arranged around the circumference of the central fixed plate. The mating block (31) on the upper surface of the movable block (3) is inserted into the mating groove (21) on the lower surface of the central fixed plate (2).

3. The mold according to claim 2, characterized in that, The upper and lower arc edges of the movable block (3) are provided with laying grooves (32). Multiple laying grooves (32) of multiple movable blocks (3) of the same single-layer mold unit (1) are connected to form an annular groove. The prepreg can be cured at the annular groove to form the reinforcing rib (5).

4. The mold according to claim 3, characterized in that, The single-layer mold unit (1) includes at least four sequentially connected movable blocks (3), each of the at least four movable blocks (3) including a plurality of first movable blocks and a plurality of second movable blocks. The first movable blocks and the second movable blocks of the single-layer mold unit (1) are alternately arranged around the outer circumference of the central fixed disk (2), wherein the inner arc length of the first movable block is less than the outer arc length, and the inner arc length of the second movable block is greater than the outer arc length.

5. The mold according to claim 4, characterized in that, The two adjacent single-layer mold units (1) are positioned and stacked in the axial direction by means of positioning pins and positioning holes.

6. The mold according to claim 5, characterized in that, The depth of the paving groove (32) is greater than 5 mm.

7. The mold according to claim 6, characterized in that, The cross section of the reinforcing rib (5) of the cylindrical composite material structure is C-shaped with the opening facing the axis of the cylindrical composite material structure. The cross section height of the reinforcing rib (5) is greater than its cross section width, and its open end is connected to the outer skin (4), while its closed end faces the inside of the cylinder.

8. A method for molding a cylindrical composite material structure, characterized in that, The molding method is applicable to the mold according to any one of claims 1 to 7, and the molding method includes: Multiple movable blocks (3) are assembled on a central fixed plate (2) to form a single single-layer mold unit (1), and prepreg is laid on the outer periphery of the movable block (3) and the laying groove (32); A mold is formed by stacking and assembling multiple single-layer mold units (1) with the prepreg laid on them to form a cylindrical composite material structure; Apply an outer skin to the outer periphery of the mold; The mold on which the skin is applied is placed in an autoclave for curing to form a cylindrical composite material structure with reinforcing ribs (5) on the inner surface.

9. The molding method according to claim 8, characterized in that, Also includes: After the movable block (3) and the central fixing plate (2) are disassembled, they are taken out from the formed cylindrical composite material structure in sequence to demold and obtain the cylindrical composite material structure with reinforcing ribs (5).

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