An integrated forming die and method for a longitudinal-transverse reinforced complex wall panel

Abstract

The present application relates to the technical field of composite material liquid forming, and particularly relates to an integrated forming die and method for a longitudinal and transverse ribbed complex wall plate. The method comprises the following steps: determining the number of split core blocks in the forming die according to the number of longitudinal and transverse ribs, and performing fiber laying on each split core block; assembling each split core block after fiber laying to form a core block combination, and laying a skin on the core block combination; sequentially performing die assembly, resin injection, curing and demolding to obtain an integrated longitudinal and transverse ribbed complex wall plate. The integrated forming die and method for the longitudinal and transverse ribbed complex wall plate aim to solve the problems of poor forming precision of the assembly surface of the longitudinal and transverse ribbed wall plate formed by the existing autoclave process, high difficulty in precise positioning of the ribs and the skin, and poor structural integrity.

Description

Technical Field

[0001] This invention relates to the field of liquid molding technology for composite materials, specifically to an integrated molding die and method for a complex wall panel with longitudinal and transverse stiffeners. Background Technology

[0002] With advancements in composite material manufacturing technology, the application of advanced composite materials in aircraft has gradually expanded from non-load-bearing or secondary load-bearing components such as radomes, skins, and rudders to primary load-bearing components such as corrugated beams, wing box sections, floor beams, and pressure frames. As primary load-bearing structural components, these materials require high strength and stiffness, resulting in generally complex structures with numerous longitudinal and transverse stiffeners, flanges, and assembly relationships, demanding high manufacturing precision. Currently, two main molding processes are employed for these complex structures: one is co-curing with adhesive, where the skin is cured first, and then the uncured stiffeners are bonded to the skin and co-cured; the other is secondary bonding, where the skin and stiffeners are cured separately and then bonded together with an adhesive film to form a single unit.

[0003] Both of the above molding methods use conventional vacuum bag autoclave molding processes, which have the following drawbacks: Firstly, it is difficult to meet the assembly precision requirements of the bag surface when molding the longitudinal and transverse stiffened wall panel structure by bag pressing; secondly, regardless of whether adhesive co-curing or secondary adhesive bonding is used, it is extremely difficult to ensure the precise positioning of the ribs and the skin, and the longitudinal and transverse ribs are separated from each other, resulting in poor overall integrity; in addition, the above molding methods all require secondary curing in the autoclave, which leads to higher manufacturing costs.

[0004] Therefore, the inventors have provided an integrated molding die and method for complex wall panels with longitudinal and transverse reinforcement. Summary of the Invention

[0005] (1) Technical problems to be solved

[0006] This invention provides an integrated molding die and method for longitudinally and transversely stiffened complex wall panels, which solves the technical problems of poor assembly surface forming accuracy, high difficulty in precise positioning of ribs and skin, and poor structural integrity in existing autoclave molding processes for longitudinally and transversely stiffened wall panels.

[0007] (2) Technical solution

[0008] The first aspect of the present invention provides an integrated molding method for a complex wall panel with longitudinal and transverse stiffening, comprising the following steps:

[0009] Based on the number of longitudinal and transverse ribs, determine the number of split core blocks in the molding die, and lay fibers on each of the split core blocks;

[0010] Each of the separate core blocks after fiber laying is assembled to form a core block assembly, and a skin is laid on the core block assembly;

[0011] The mold is assembled, resin is injected, cured and demolded in sequence to obtain a complex wall panel with longitudinal and transverse reinforcement.

[0012] Furthermore, determining the number of separate core blocks within the molding die based on the number of longitudinal and transverse ribs, and then laying fibers on each of the separate core blocks, specifically includes the following steps:

[0013] Based on the number of longitudinal and transverse ribs, the wall panel to be formed is divided into several parts, and each part is designed with a layup group;

[0014] The core block of the molding die is designed according to the number of the layup groups, and each layup group corresponds to one of the split core blocks;

[0015] The fiber layup of the corresponding layer group is completed on the five sides of each of the split core blocks.

[0016] Furthermore, the fiber layup of the corresponding ply groups on the five sides of each of the split core blocks specifically involves:

[0017] The split core blocks are laid using dry fibers with a setting agent that are compatible with the resin, and the split core blocks are preheated before laying.

[0018] Furthermore, when laying the fibers, the fibers are cut at the R-corners of the split core blocks.

[0019] Furthermore, the cut positions of each fiber layer are staggered.

[0020] Furthermore, each of the separate core blocks undergoes a hot-pressing process after the fiber is laid.

[0021] Furthermore, the process of assembling each of the fiber-laid individual core blocks to form a core block assembly, and then applying a skin to the core block assembly, specifically includes the following steps:

[0022] Each of the laid-out modular core blocks is combined, and the four sides of each modular core block are combined with adjacent modular core blocks to form the longitudinal and transverse ribs.

[0023] The skin is laid on the core block assembly, so that the longitudinal and transverse ribs and the skin form a complex wall panel prefabricated component with longitudinal and transverse reinforcement.

[0024] Furthermore, the layers of the skin are symmetrically distributed with the layers of the core assembly.

[0025] A second aspect of the present invention provides a molding die for an integrated molding method of a complex wall panel with longitudinal and transverse stiffening, comprising an upper die and a lower die, wherein the upper die and the lower die are fastened together, and the lower die contains a plurality of separate core blocks corresponding one-to-one with each layup group to form longitudinal stiffeners and transverse stiffeners on the longitudinal and transverse stiffening wall panel.

[0026] Furthermore, the molding die also includes inserts, with multiple inserts located around the split core block.

[0027] (3) Beneficial effects

[0028] In summary, this invention determines the required number of core blocks and the number of core block and skin layers based on the number of longitudinal and transverse ribs, rib thickness, skin thickness, and single-layer thickness of the fibers used, and completes the laying of each core block; after assembling each core block, the skin is laid on the bottom surface of the core block; then the mold is assembled, resin is injected, cured, and demolded to obtain an integrated longitudinal and transverse ribbed wall panel. This wall panel has higher surface accuracy, is more conducive to assembly, and adopts liquid molding technology, resulting in lower manufacturing costs. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a structural schematic diagram of a complex wall panel with longitudinal and transverse reinforcement provided in an embodiment of the present invention;

[0031] Figure 2 This is a schematic flowchart of an integrated molding method for a complex wall panel with longitudinal and transverse stiffening provided in an embodiment of the present invention;

[0032] Figure 3 This is a schematic diagram of the structure of an integrated molding die for a complex wall panel with longitudinal and transverse reinforcement provided in an embodiment of the present invention;

[0033] Figure 4 This is a schematic diagram of a combined structure of split core blocks provided in an embodiment of the present invention;

[0034] Figure 5 This is a schematic diagram of a fiber layup structure provided in an embodiment of the present invention;

[0035] Figure 6 This is a front view of the lower mold of an integrated molding die provided in an embodiment of the present invention;

[0036] Figure 7 yes Figure 6 Sectional view of AA;

[0037] Figure 8 This is a left view of the lower mold of an integrated molding die provided in an embodiment of the present invention;

[0038] Figure 9 yes Figure 8 BB section view.

[0039] In the picture:

[0040] 1-Upper mold; 2-Lower mold; 3-Separated core block; 4-Installation block; 5-Connector; 100-Longitudinal and transverse stiffened wall panel; 101-Longitudinal rib; 102-Transverse rib; 103-Assembly area; 104-Assembly hole; 105-Flanged edge; 106-Bottom skin; 200-Fiber layup; 201-Core block fiber layup; 202-Assembled fiber layup; 203-Bottom skin fiber layup. Detailed Implementation

[0041] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present invention by way of example, but should not be used to limit the scope of the present invention. That is, the present invention is not limited to the described embodiments, and any modifications, substitutions and improvements to the parts, components and connection methods are covered without departing from the spirit of the present invention.

[0042] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0043] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to 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 invention.

[0044] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set" and "install" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0045] Figure 2This is a flowchart illustrating an integrated molding method for a complex wall panel with longitudinal and transverse stiffening provided in an embodiment of the present invention, as shown below. Figure 2 As shown, the method may include the following steps:

[0046] S100. Based on the number of longitudinal and transverse ribs, determine the number of split core blocks in the molding die, and lay fibers on each split core block.

[0047] S200: Assemble each individual core block after fiber laying to form a core block assembly, and lay a skin on the core block assembly;

[0048] S300, mold assembly, resin injection, curing and demolding are carried out in sequence to obtain an integrated longitudinal and transverse stiffened complex wall panel.

[0049] In the above embodiment, in step S100, the panel component is divided into several parts according to the number of longitudinal and transverse ribs [number of parts = (n longitudinal + 1) * (n transverse + 1)], and each part is designed with a layup group. In this step, to avoid deformation after the component is formed, the fiber layup angles of adjacent layup groups should be kept symmetrical during the design.

[0050] In step S200, the core block of the molding die is designed according to the number of layup groups. Each layup group corresponds to a split core block. The fiber of the corresponding layup group is laid on five sides of each split core block, leaving one side empty to facilitate the core block to be removed after curing.

[0051] In this step, to ensure the core block can be demolded after the part has cured, the core block can be further divided into sections according to the draft angle of the ribs. When laying the fibers, to avoid fiber accumulation at the radius (R) corners of the aforementioned split core blocks, the fibers can be cut at the R corners. To avoid stress concentration, the cut positions of the multi-layer fibers should be staggered.

[0052] In addition, because the fibers are relatively loose, in order to ensure that the separate core blocks 3 can be assembled in place, each separate core block 3 is subjected to hot pressing after the fibers are laid, so that it is as close as possible to the theoretical thickness.

[0053] The laid-out split core blocks 3 are combined, and the four sides of the split core blocks are combined with other split core blocks to form longitudinal and transverse inverted "T" shaped ribs; a skin layer is laid on the bottom surface of the assembled core blocks so that the longitudinal and transverse ribs formed by the core blocks and the bottom skin form a whole.

[0054] In this step, according to design requirements, after the separate core blocks 3 are assembled into a composite body in the direction where greater stiffness is required, fibers are laid on the four sides and bottom surface of the composite body to make the ribs in that direction thicker and more continuous, thereby increasing the stiffness.

[0055] To facilitate the assembly of the modular core blocks, a connecting mechanism can be designed on the side of the modular core block that is not covered with fiber. To prevent deformation after the part has cured, the bottom skin layer should be designed symmetrically with the bottom layer of the modular core block.

[0056] In addition, a frame-shaped ply assembly (assembly area 103) can be added around the assembled core block. The ply on the side of the core block that corresponds to the frame-shaped ply assembly can be inserted into the frame-shaped ply assembly, so that the core block ply and the frame-shaped reinforcing ply assembly form a whole.

[0057] In step S300, the upper and lower halves of the RTM molding mold are assembled, and resin is injected into the mold. The longitudinal and transverse stiffened panel structure is cured and molded according to the resin curing process. After curing, the longitudinal and transverse stiffened panel, along with the core block, is removed from the molding mold. Then, the core blocks are pulled out one by one to complete the demolding of the longitudinal and transverse stiffened panel structure. The use of liquid molding technology results in lower part development costs.

[0058] As an optional implementation, in step S100, the number of split core blocks in the molding die is determined based on the number of longitudinal and transverse ribs, and fiber laying is performed on each split core block, specifically including the following steps:

[0059] S101. Based on the number of longitudinal and transverse ribs, divide the wall panel to be formed into several parts, and design a layup group for each part.

[0060] S102. Design the core block of the molding die according to the number of layup groups, with each layup group corresponding to a separate core block;

[0061] S103. Complete the fiber laying of the corresponding layer group on the five sides of each split core block.

[0062] The above provides the number of separate core blocks and the specific laying method to facilitate the subsequent RTM molding process, thereby achieving the integrated molding of the longitudinally and transversely stiffened wall panels.

[0063] As an optional implementation, in step S103, fiber layup of the corresponding layer group is completed on all five sides of each split core block. Specifically, dry fibers with a setting agent compatible with the resin are used to lay the split core block, and the split core block is preheated before laying. The specific method of fiber layup on each side of the split core block is described above. Since fiber layup is required on all five sides of the split core block, and dry fibers have poor layup properties at corners, dry fibers with a setting agent compatible with the resin can be used. The split core block is preheated before laying to ensure fiber layupability.

[0064] As an optional implementation, in step S200, each individual core block after fiber laying is assembled to form a core block assembly, and a skin is laid on the core block assembly, including the following steps:

[0065] S201. Combine each laid sub-core block, and combine the four sides of the sub-core block with the adjacent sub-core blocks to form longitudinal and transverse ribs.

[0066] S202. Lay the skin on the core block assembly so that the longitudinal and transverse ribs and the skin form a complex wall panel prefabricated component with longitudinal and transverse reinforcement.

[0067] The above describes the specific laying method for complex wall panels with longitudinal and transverse stiffening, so as to facilitate the subsequent RTM molding process and thus achieve the integrated molding of the longitudinal and transverse stiffened wall panels.

[0068] Figure 3 This is a schematic diagram of the structure of an integrated molding die for a complex wall panel with longitudinal and transverse stiffening provided in an embodiment of the present invention, as shown below. Figure 3 As shown, the molding die may include an upper die 1 and a lower die 2. The upper die 1 and the lower die 2 are fastened together. The lower die 2 is provided with a plurality of separate core blocks 3 that correspond one-to-one with each ply group to form longitudinal ribs 101 and transverse ribs 102 on the longitudinal and transverse stiffened wall panel 100.

[0069] In the above embodiment, by setting a split core block 3 in the mold cavity of the lower mold 2, the gap between two adjacent split core blocks 3 is formed by RTM molding to form crisscrossing longitudinal ribs 101 and transverse ribs 102, thereby realizing the integral molding of ribs and skin.

[0070] As an optional implementation method, such as Figure 6-9 As shown, the molding die also includes inserts 4, with multiple inserts 4 located around the split core block 3. In order to ensure that the assembled core block can be smoothly positioned in the lower mold 2 of the molding die, four wedge-shaped inserts 4 are designed around the core block. By tightening the wedge-shaped inserts, the split core block 3 is compressed and assembled into place.

[0071] Example 1

[0072] Using the RTM (Resin Transfer Molding) molding technology of this invention, as shown in the figure, the following can be prepared: Figure 1 The diagram shows a longitudinally and transversely reinforced panel structure. This component consists of two longitudinal ribs 101, three transverse ribs 102, an assembly area 103, and a flange 105. The assembly area 103 has multiple assembly holes 104. The flange 105 forms an acute angle with the bottom skin. Furthermore, the component requires high rigidity along the longitudinal ribs, with a rib thickness of 2mm, a transverse rib thickness of 1.6mm, and a skin thickness of 2mm in the "U"-shaped area. This component was fabricated using carbon fiber fabric CF8611 (single layer thickness 0.2mm) with a setting agent / Actech 1304 epoxy resin. The specific process steps are as follows:

[0073] (1) The part has two longitudinal ribs 101 and three transverse ribs 102, which divide the part into (2+1)×(3+1)=12 parts. The molding die needs to be designed with 12 separate core blocks.

[0074] (2) Since the flange 105 and the bottom skin 106 form an acute angle, the split core block needs to be further divided into sections for easier demolding, such as... Figure 4 As shown; before laying, first assemble multiple separate core blocks using connector 5, and then preheat the 12 separate core blocks at 80℃; then lay 4 layers of carbon fiber CF8611 with a setting agent on the separate core blocks according to the layup angle [(0,90) / ±45 / (0,90) / ±45]. To improve fiber layability, the laying surface can be preheated and compacted using an iron not exceeding 80℃. Lay the fibers on five sides of the separate core blocks, leaving one side untouched for easy demolding. To prevent excessive fiber accumulation at the edges of the core blocks, cuts can be made, but the cuts for multiple layers of fibers should be staggered. After the core blocks are laid, hot press them at 80℃ to make the fluffy fibers as close as possible to the theoretical thickness.

[0075] (3) Arrange the laid modular core blocks, with four modular core blocks together to form a composite unit. Connect the modular core blocks at their bottom surfaces using connectors 5. Figure 5 As shown. Then, a layer of (0,90) fiber layup is completed on the five sides of the assembly (layup method is the same as core block layup), making the longitudinal ribs thicker and with continuous fibers, thus improving the stiffness in that direction. Core block fiber layup 201 and assembly fiber layup 202 are as follows. Figure 5 As shown. After the three composite fiber layups 202 are laid, they are hot-pressed at 80°C and placed in the lower mold cavity of the molding die. The corresponding split core blocks 3 are then assembled by tightening the four wedge-shaped inserts 4. The fiber layup is completed in the assembly area 103 according to the design. The fiber layup of the split core blocks on the assembly area 103 side can be inserted into the layup of the assembly area 103 to improve the overall integrity of the structure. Finally, the bottom skin fiber layup 203 [(0,90) / ±45 / (0,90) / ±45 / (0,90)] is laid. Among them, the core block fiber layup 201, the composite fiber layup 202 and the bottom skin fiber layup 203 together constitute the fiber layup 200.

[0076] (4) Assemble the upper and lower halves of the RTM molding die, such as... Figure 3 As shown, resin injection and curing are completed through the injection port according to the process parameters of Actech 1304 epoxy resin. Excess resin flows out from the injection port. After curing, the longitudinal and transverse stiffened wall panel together with the split core block 3 are taken out from the lower mold of the molding mold. Then, 12 core blocks are pulled out in sequence to obtain the longitudinal and transverse stiffened wall panel 100.

[0077] It should be noted that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. Furthermore, for the sake of brevity, detailed descriptions of known methods and techniques are omitted here.

[0078] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art without departing from the scope of the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.

Claims

1. An integrated molding method for a complex wall panel with longitudinal and transverse reinforcement, characterized in that, The method includes the following steps: Based on the number of longitudinal and transverse ribs, determine the number of split core blocks in the molding die, and lay fibers on each of the split core blocks; Each of the fiber-laid core blocks is assembled to form a core block assembly, and a skin is laid on the core block assembly; a frame-shaped ply group is added around the core block assembly, and the ply on the side of the core block assembly corresponding to the frame-shaped ply group is inserted into the frame-shaped ply group, so that the ply of the core block assembly and the frame-shaped ply group form a whole; The mold is assembled, resin is injected, cured and demolded in sequence to obtain an integrated, longitudinally and transversely reinforced complex wall panel. The process of assembling each of the fiber-laid individual core blocks to form a core block assembly, and then applying a skin onto the core block assembly, specifically includes the following steps: Each of the laid-out modular core blocks is combined, and the four sides of each modular core block are combined with adjacent modular core blocks to form the longitudinal and transverse ribs. The skin is laid on the core block assembly so that the longitudinal and transverse ribs and the skin form a complex wall panel prefabricated component with longitudinal and transverse reinforcement; The skin layers are symmetrically distributed with the core block layers.

2. The integrated molding method for longitudinally and transversely reinforced complex wall panels according to claim 1, characterized in that, The process of determining the number of separate core blocks within the molding die based on the number of longitudinal and transverse ribs, and then laying fibers on each of the separate core blocks, specifically includes the following steps: Based on the number of longitudinal and transverse ribs, the wall panel to be formed is divided into several parts, and each part is designed with a layup group; The core block of the molding die is designed according to the number of the layup groups, and each layup group corresponds to one of the split core blocks; The fiber layup of the corresponding layer group is completed on the five sides of each of the split core blocks.

3. The integrated molding method for longitudinally and transversely reinforced complex wall panels according to claim 2, characterized in that, The fiber layup of the corresponding layer group is completed on the five sides of each of the split core blocks, specifically as follows: The split core blocks are laid using dry fibers with a setting agent that are compatible with the resin, and the split core blocks are preheated before laying.

4. The integrated molding method for longitudinally and transversely reinforced complex wall panels according to claim 2, characterized in that, When laying the fibers, the fibers are cut at the R-corners of the split core blocks.

5. The integrated molding method for longitudinally and transversely reinforced complex wall panels according to claim 4, characterized in that, The cuts of each fiber layer are staggered.

6. The integrated molding method for longitudinally and transversely reinforced complex wall panels according to claim 2, characterized in that, Each of the separate core blocks is subjected to hot pressing after the fiber is laid.

Images