I-shaped cross-section cross beam composite material reinforcing frame, forming die and forming method

Abstract

The present application relates to the technical field of composite structure forming, and discloses a H-shaped section cross beam composite material reinforcing frame, a forming die and a forming method. The forming die of the H-shaped section cross beam composite material reinforcing frame is composed of an outer die, an inner die, a side ejector pin, an outer side silica gel plate, an inner side silica gel plate, an upper plate silica gel plate, an upper cover plate, a lower bottom plate, a bottom plate silica gel plate and a standard part. The inner die, the inner side silica gel plate, the outer side silica gel plate and the outer die are sequentially arranged from the inside to the outside along the radial direction, and the upper plate silica gel plate and the upper cover plate are sequentially combined with the upper end surfaces of the outer die and the inner die. The bottom plate silica gel plate and the lower bottom plate are sequentially combined with the lower end surfaces of the outer die and the inner die, and are fixed by the side ejector pin. The standard part is used for temporary arrangement in the inner cavity of the combined die to perform testing. The forming precision and internal quality of the component are ensured, and the production yield is effectively improved to solve the technical problems of combined die difficulty, uneven pressure transmission and poor controllability of product quality.

Description

Technical Field

[0001] This invention relates to the field of composite structure molding technology, and in particular, to a composite material reinforcing frame for an I-shaped cross-section grid beam, a molding die, and a molding method. Background Technology

[0002] With the widespread application of composite materials in high-end equipment manufacturing fields such as aerospace, the requirements for lightweight structures, integrated design, and reliable performance are increasing. In particular, composite reinforced frames with I-beam cross-sections are gradually becoming the preferred solution for main load-bearing components such as fuselages and bulkheads due to their excellent specific stiffness and specific strength. Currently, these components are mostly formed using a prepreg-autoclave process, and the molds are typically integral steel structures.

[0003] However, in the process of forming I-beam cross-section composite reinforced frames using traditional steel molds, the complex structure, deep and narrow cavities, and numerous corners of the components lead to significant technical difficulties in the mold closing process. Specifically, when performing mold closing operations at room temperature, the rigid mold is prone to interference with the preform, causing the reinforcing fibers in the layup to slip or even buckle. This not only affects dimensional accuracy but also introduces difficult-to-detect internal defects such as delamination and porosity. If, to avoid such problems, pressure is applied during the heating process to soften the material before mold closing, it is difficult to effectively control the relative position of the mold cavity and the blank. This also leads to large deviations in product dimensions and uneven internal pressure distribution, resulting in poor product quality consistency and a low pass rate. Summary of the Invention

[0004] This invention provides a composite material reinforcing frame with an I-shaped cross-section grid beam, a molding die, and a molding method, which ensures the molding accuracy and internal quality of the component and effectively improves the production yield. This solves the technical problems of difficult mold closing, uneven pressure transmission, and poor product quality control when using traditional steel molds to mold complex cross-section composite material structures.

[0005] According to one aspect of the present invention, a molding die for a composite material reinforcing frame with an I-shaped cross-section is provided, comprising an outer mold, an inner mold, a side push rod, an outer silicone plate, an inner silicone plate, an upper silicone plate, an upper cover plate, a lower bottom plate, a bottom silicone plate, and standard parts; the inner mold, inner silicone plate, outer silicone plate, and outer mold are arranged radially from the inside to the outside; the upper silicone plate and the upper cover plate are sequentially molded onto the upper end faces of the outer mold and the inner mold; the bottom silicone plate and the lower bottom plate are sequentially molded onto the lower end faces of the outer mold and the inner mold, and are fixed by the side push rod; the standard parts are temporarily placed in the inner cavity of the mold for testing.

[0006] Furthermore, the outer mold, inner mold, side ejector pin, upper cover plate, and lower base plate are made of Q235 steel; the outer silicone plate, inner silicone plate, upper silicone plate, and base silicone plate are made of modified thermal expansion silicone rubber or flexible high-temperature resistant silicone rubber with excellent thermal expansion coefficient, forming a variable gradient composite elastic layer.

[0007] According to another aspect of the present invention, a molding method for an I-shaped cross-section grid beam composite material reinforcing frame is also provided, using the above-mentioned molding mold for the I-shaped cross-section grid beam composite material reinforcing frame, comprising the following steps: S100, assembling the inner mold, and sequentially bonding the thermally expandable silicone soft mold to the inner mold and the outer mold in the radial direction of the inner mold, and then bonding the pressure equalizing plate to both ends of the thermally expandable silicone soft mold in the axial direction, and applying a shaping spray adhesive to the contact surfaces of the inner mold, the outer mold, the thermally expandable silicone soft mold and the pressure equalizing plate before bonding; S200, laying carbon fiber prepreg on the pressure equalizing plates on both ends of the outer mold and both ends of the inner mold, and performing vacuum sealing and compaction treatment during the process until the theoretical dimensions required for the product are achieved; S300: Place the base silicone sheet on the lower base plate, and sequentially close the lower base plate with the lower end faces of the inner and outer molds using side push rods, filling the mold gaps; S400: Lay prepreg from the upper end faces of the outer and inner molds to form the first I-beam preform, and sequentially place the upper silicone sheet and upper cover plate on the first I-beam preform after laying, closing the mold; S500: Flip the mold and remove the lower base plate, taking out the base silicone sheet; S600: Lay prepreg from the lower end faces of the outer and inner molds to form the second I-beam preform, and sequentially place the base silicone sheet and lower base plate on the second I-beam preform after laying, closing the mold; S700: Perform curing and demolding sequentially to obtain an I-shaped cross-section grid beam composite material reinforcing frame.

[0008] Furthermore, the assembly of the inner mold in step S100 specifically involves: placing the component inserts on the worktable according to the component insert number sequence to assemble the inner mold.

[0009] Furthermore, the assembly ensures dimensional accuracy through locating pin holes and is connected by bolts.

[0010] Further, the shaping adhesive used in step S100 is CRT-77, and the thermal expansion silicone soft mold includes an outer silicone plate and an inner silicone plate; the bonding process in step S100 is as follows: CRT-77 shaping adhesive is applied to the contact surfaces of the outer silicone plate, the inner silicone plate, the outer mold, and the inner mold respectively, and the outer silicone plate and the inner silicone plate are bonded to the outer mold and the inner mold respectively, and then CRT-77 shaping adhesive is applied to the outer side of the outer silicone plate and the inner silicone plate along the axial direction respectively, and the pressure equalizing plate is bonded to the outer side of the outer silicone plate and the inner silicone plate respectively.

[0011] Furthermore, the prepreg laying in steps S400 and S600 is carried out on a compaction fixture, and each layer is compacted with a plastic scraper, and vacuum sealing compaction is performed during the process; the prepreg laying uses epoxy resin carbon fiber unidirectional tape, and is laid in combination of 0°, +45°, -45° and 90° laying angles respectively.

[0012] Further, the mold closing in step S400 is specifically as follows: the outer mold is pushed to the preset position using the side ejector rod, and then fastened using the positioning pin and bolts. The upper cover plate is fixed to the position of the inner mold and the outer mold using the positioning pin. After the position is fixed, the bolts are used to tighten them. After all the bolts are tightened, all mold closing gaps must be measured to be less than 0.1mm. After completing the above operations, the positioning pins are removed. The mold closing in step S600 adopts the same mold closing process as in step S400.

[0013] Furthermore, the filling of the mold gap in step S300 specifically involves filling the rounded gap and triangular area of ​​the mold gap between the outer mold and the inner mold with carbon twisted yarn until it is slightly higher than the end face of the outer mold and the end face of the inner mold. The filling requires first measuring the mold gap, and then pre-impregnating the yarn to perform quantitative filling, thereby ensuring that there will be no material shortage or overflow in the mold gap area.

[0014] According to another aspect of the present invention, a composite material reinforcing frame with an I-shaped cross section is also provided, which is prepared by the above-described molding method for the composite material reinforcing frame with an I-shaped cross section.

[0015] The present invention has the following beneficial effects: 1. Achieved smooth mold closing at room temperature, avoiding fiber damage: By setting inner and outer silicone plates between the inner and outer steel molds, the soft silicone rubber material at room temperature provides the necessary fitting clearance and tolerance for mold closing, allowing the rigid mold components to easily close into place. This completely solves the problem of prepreg fibers slipping, buckling, or even breaking during mold closing caused by interference in traditional all-steel molds, eliminating internal quality defects caused by this at the source.

[0016] 2. It achieves uniform and efficient pressure transmission during the heating and curing process, ensuring the density of the product: During the curing and heating stage, the silicone rubber components (inner silicone plate, outer silicone plate, upper silicone plate, and bottom silicone plate) expand due to heat, and their volume increases significantly. This controlled expansion behavior can fill all the spaces in the mold cavity and apply uniform and isotropic lateral pressure to all surfaces of the prepreg blank. It can effectively remove interlayer gas, reduce porosity, promote resin flow and fiber wetting, thereby significantly improving the interfacial bonding quality of the composite material, eliminating defects such as looseness and delamination, and ensuring the mechanical properties of the part.

[0017] 3. Effectively ensures the molding accuracy and dimensional stability of the parts: The core part of the mold structure consists of a rigid outer mold, inner mold, upper cover plate, lower base plate and side ejector rod. These components together form a stable rigid frame, providing accurate surface reference and strong support for the entire molding process; thermally expandable silicone rubber plays a role in this rigid frame, its expansion force is constrained and guided to the blank, so the final molded component's external dimensions are guaranteed by the rigid mold, avoiding the dimensional deviation and deformation problems that may be caused by relying solely on soft mold molding, and achieving high-precision molding.

[0018] 4. Improved process reliability and production yield: The standard parts facilitate mold closing tests and gap checks before formal curing, further optimizing and verifying process parameters; the whole system combines the dimensional accuracy of steel molds with the pressure uniformity of soft molds, separating and optimizing the mold closing operation and curing process, greatly reducing the difficulty of operation and dependence on worker experience, making the molding process more stable, controllable and repeatable, thereby systematically improving the manufacturing yield of complex cross-section composite material structural parts.

[0019] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the intermediate mold of the molding die for the composite material reinforcing frame of the I-shaped cross-section grid beam according to a preferred embodiment of the present invention; Figure 2 This is a schematic diagram of the lower mold of the molding die for the composite material reinforcing frame of the I-shaped cross-section grid beam according to a preferred embodiment of the present invention; Figure 3 This is a schematic diagram of the upper mold of the molding die for the composite material reinforcing frame of the I-shaped cross-section grid beam according to a preferred embodiment of the present invention.

[0021] Legend: 1. Outer mold; 2. Inner mold; 3. Side ejector pin; 4. Outer silicone plate; 5. Inner silicone plate; 6. Upper silicone plate; 7. Upper cover plate; 8. Lower base plate; 9. Base silicone plate. Detailed Implementation

[0022] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0023] like Figure 1 , Figure 2 and Figure 3As shown, the molding die for the composite material reinforcing frame of the I-shaped cross-section grid beam in this embodiment consists of an outer mold 1, an inner mold 2, a side push rod 3, an outer silicone plate 4, an inner silicone plate 5, an upper silicone plate 6, an upper cover plate 7, a lower bottom plate 8, a bottom silicone plate 9, and standard parts. The inner mold 2, inner silicone plate 5, outer silicone plate 4, and outer mold 1 are arranged radially from the inside to the outside. The upper silicone plate 6 and the upper cover plate 7 are sequentially molded onto the upper end faces of the outer mold 1 and the inner mold 2. The bottom silicone plate 9 and the lower bottom plate 8 are sequentially molded onto the lower end faces of the outer mold 1 and the inner mold 2, and are fixed by the side push rod 3. The standard parts are temporarily placed in the inner cavity of the mold for testing. This invention relates to a molding die for a composite reinforced frame with an I-beam cross-section. By placing an inner silicone rubber plate 5 and an outer silicone rubber plate 4 between the inner steel mold 2 and the outer mold 1, the soft silicone rubber material at room temperature provides the necessary clearance and tolerance for mold closing, allowing the rigid mold components to easily close into place. This completely solves the problem of prepreg fibers slipping, buckling, or even breaking during mold closing caused by interference in traditional all-steel molds, thus eliminating internal quality defects caused by this at the source. During the curing and heating stage, the silicone rubber components (inner silicone rubber plate 5, outer silicone rubber plate 4, upper silicone rubber plate 6, and bottom silicone rubber plate 9) expand significantly due to heat. This controlled expansion behavior fills all the space within the mold cavity and applies uniform and isotropic lateral pressure to all surfaces of the prepreg blank, effectively eliminating interlayer gas, reducing porosity, promoting resin flow and fiber wetting, thereby significantly improving the interfacial bonding quality of the composite material, eliminating defects such as looseness and delamination, and ensuring... The mechanical properties of the molded parts are verified. The core part of the mold structure consists of a rigid outer mold 1, an inner mold 2, an upper cover plate 7, a lower base plate 8, and a side push rod 3. These components together form a stable rigid frame, providing accurate surface reference and strong support for the entire molding process. The thermally expandable silicone rubber plays a role within this rigid frame. Its expansion force is constrained and guided to the blank. Therefore, the final molded component's external dimensions are guaranteed by the rigid mold, avoiding dimensional deviations and deformation problems that may occur when relying solely on soft mold molding, thus achieving high-precision molding. The setting of standard parts facilitates mold closing tests and gap checks before formal curing, further optimizing and verifying process parameters. The entire system combines the dimensional accuracy of the steel mold with the pressure uniformity of the soft mold, separating and optimizing the mold closing operation and curing process respectively. This greatly reduces the difficulty of operation and the dependence on worker experience, making the molding process more stable, controllable, and repeatable, thereby systematically improving the manufacturing yield of complex cross-section composite material structural parts.The molding die for the composite material reinforcing frame of the I-shaped cross-section grid beam of this invention, through a design that combines rigidity and flexibility, cleverly utilizes the properties of thermally expandable silicone rubber material. It simultaneously overcomes the two major problems faced by traditional all-steel molds when molding complex I-shaped cross-section grid beam structures: difficulty in room temperature mold closing and uneven heating pressure. While ensuring the high-precision shape of the component, it significantly improves its internal quality, providing a reliable process equipment guarantee for the efficient and stable manufacturing of high-performance composite material reinforcing frames.

[0024] In this embodiment, the outer mold 1, inner mold 2, side ejector pin 3, upper cover plate 7, and lower base plate 8 are made of Q235 steel; the outer silicone plate 4, inner silicone plate 5, upper silicone plate 6, and lower silicone plate 9 are made of modified thermally expanding silicone rubber or flexible, high-temperature resistant silicone rubber with excellent thermal expansion coefficient, forming a variable-gradient composite elastic layer. The outer mold 1, inner mold 2, upper cover plate 7, lower base plate 8, and side ejector pin 3, made of Q235 steel, constitute a rigid frame, fully utilizing the material's high strength, excellent rigidity, and good thermal stability. This provides structural support, dimensional reference, and surface accuracy for the entire mold system, ensuring high precision and stability of the final composite material component shape, effectively resisting various thermal and operational stresses during the curing process, and preventing mold deformation. Each silicone sheet component utilizes modified thermally expandable silicone rubber or a similar flexible, high-temperature resistant material, leveraging its core functions of room-temperature flexibility and high-temperature expansion. During the room-temperature molding stage, its flexibility provides necessary tolerance space and buffering, allowing the rigid mold assembly to close easily and without interference, completely avoiding damage to the prepreg fibers. During the heat curing stage, this material exhibits significant and controllable volume expansion upon heating, perfectly filling the cavity and applying uniform, stable, and isotropic lateral pressure to the prepreg blank. This inside-out expansion pressure ensures sufficient resin flow within complex cross-sections and uniform fiber impregnation, thereby eliminating porosity, preventing delamination, and improving product density. The variable-gradient composite elastic layer design further optimizes pressure distribution and boundary effects. Its mechanical properties (such as modulus and expansion rate) exhibit a gradient change in the thickness direction. This structure better coordinates the mechanical transition between the rigid mold and the flexible blank, alleviating stress concentration at the interface and resulting in smoother and more uniform pressure transmission from the steel mold to the composite material, contributing to further improving the overall uniformity of the component's quality. Q235 steel offers excellent machinability and cost-effectiveness, ensuring the manufacturing precision and durability of core mold components. The selected silicone rubber material possesses high-temperature resistance, capable of withstanding the high-temperature environment during the composite material curing process, maintaining the stability of its chemical and physical properties, and ensuring the long-term reliability and reusability of the mold.

[0025] The molding method of the I-shaped cross-section grid beam composite material reinforcing frame in this embodiment uses the above-mentioned molding mold for the I-shaped cross-section grid beam composite material reinforcing frame, including the following steps: S100, assemble the inner mold, and along the radial direction of the inner mold 2, sequentially bond the thermal expansion silicone soft mold to the inner mold and the outer mold 1 respectively, and then bond the pressure equalizing plate to both ends of the thermal expansion silicone soft mold in the axial direction. Before bonding, apply shaping spray adhesive to the contact surfaces of the inner mold 2, the outer mold 1, the thermal expansion silicone soft mold and the pressure equalizing plate respectively; S200, lay carbon fiber prepreg on the pressure equalizing plates on both ends of the outer mold 1 and both ends of the inner mold, and perform vacuum sealing and compaction treatment during the process until the theoretical size required by the product is achieved; S300, place the base silicone plate 9. Place it on the lower base plate 8, and use the side push rod 3 to sequentially close the lower base plate 8 with the lower end face of the inner mold 2 and the outer mold 1, and fill the mold gap; S400. Lay prepreg from the upper end face of the outer mold 1 and the inner mold 2 to form the first I-beam preform, and place the upper silicone plate 6 and the upper cover plate 7 on the first I-beam preform after laying in sequence to close the mold; S500. Turn the mold over and remove the lower base plate 8, and take out the base plate silicone plate 9; S600. Lay prepreg from the lower end face of the outer mold 1 and the inner mold 2 to form the second I-beam preform, and place the base plate silicone plate 9 and the lower base plate 8 on the second I-beam preform after laying in sequence to close the mold; S700. Perform curing and demolding in sequence to obtain the I-shaped cross section grid beam composite material reinforcing frame. The present invention discloses a molding method for a composite material reinforcing frame with an I-beam cross-section. First, it achieves precise, step-by-step, and operable mold closing, completely avoiding damage to the fiber preform. By first completing the mold closing of the lower half of the mold, and then laying and constructing the first I-beam preform from one end, and then constructing the second I-beam preform from the other end by flipping the mold and removing the bottom mold, the complex grid beam structure is decomposed into two relatively simple I-beam molding processes. This step-by-step implementation scheme greatly reduces the difficulty and risk of a one-time overall mold closing, allowing each mold closing operation to be completed under controllable conditions, fundamentally avoiding slippage, buckling, or breakage of the prepreg fibers caused by forced mold closing. Secondly, it ensures uniform and efficient pressure transfer during the molding process, guaranteeing the uniformity and density of the product's internal quality. Applying a shaping adhesive to each contact surface enhances the thermal conductivity between the mold-silicone-prepreg system, allowing heat to be quickly and evenly transferred to the silicone rubber components and prepreg blank. This promotes synchronous and uniform thermal expansion of the silicone rubber, generating isotropic lateral pressure. This effectively eliminates interlayer bubbles, promotes resin flow, and ensures sufficient resin impregnation of the fibers, thereby significantly reducing internal defects such as porosity and delamination, and improving the interlaminar shear strength and overall mechanical properties of the composite material.Secondly, the sequential design of the process steps ensures the dimensional accuracy and surface quality of complex structural products. Rigid molds (outer mold 1, inner mold 2, upper cover plate 7, lower base plate 8) provide a stable reference surface for the entire molding process. The step-by-step laying and mold-closing strategy ensures that each I-beam is precisely formed within the closed rigid frame. The overall dimensions and shape of the final product are guaranteed by these high-precision steel mold surfaces, effectively avoiding dimensional deviations and shape distortions caused by uneven pressure or mold interference in traditional processes. Finally, the process controllability and repeatability are improved, systematically increasing the production yield. Each step, such as vacuum sealing and compaction, and sequential mold closing, has clear operating standards and inspection points, reducing operational difficulty and over-reliance on worker experience. The entire process decomposes the complex grid beam forming into multiple standardized and repeatable sub-steps, making the process more stable and controllable, thereby systematically improving product quality consistency and production yield. The molding method of this invention solves the three major technical bottlenecks faced by the traditional one-time integral molding process in manufacturing complex I-shaped cross-section grid beam structures—fiber damage, uneven pressure, and dimensional control—by adopting a step-by-step construction and sequential mold-closing process strategy, as well as auxiliary means to enhance thermal conductivity and uniform expansion. It simultaneously ensures the excellent internal quality and precise external morphology of the components, providing a practical and feasible process path for the efficient, stable, and large-scale manufacturing of high-performance composite material reinforced frames.

[0026] In this embodiment, the assembly of the inner mold in step S100 specifically involves: placing the component inserts on the workbench according to their numbering order to assemble the inner mold 2. By presetting the component insert numbering order, the assembly process of the inner mold 2 is transformed into a repeatable and traceable standard process, which effectively guides operators to assemble according to the predetermined order and position, avoiding problems such as component misalignment, uneven gaps, or reference surface deviation that may be caused by arbitrary manual operation. This ensures the assembly accuracy of the core mold component—the inner mold 2—from the source, providing an accurate and reliable reference for subsequent silicone sheet bonding, prepreg laying, and final product molding. The potentially complex inner mold 2 is decomposed into multiple insert components with clear numbers, allowing large or complex molds to be managed and assembled smoothly by breaking them down into smaller parts. The laying and assembly process provides operators with a clear and intuitive working view and ample operating space. Compared to assembling in narrow or vertical spaces, it significantly reduces the difficulty of operation, decreases the risk of installation errors, and improves assembly efficiency and the reliability of production preparation. The clear numbering system and sequence requirements make the assembly status of the molds inspectable and verifiable. Quality inspectors can quickly confirm whether the assembly is correct based on the numbering sequence, ensuring that each set of molds has a consistent initial state before being put into use. This standardized operation mode reduces quality fluctuations caused by individual differences in operation, laying a solid foundation for the stability of the entire composite material molding process and the improvement of product yield.

[0027] In this embodiment, dimensional accuracy is ensured through locating pin holes, and the components are connected by bolts. The locating pin holes provide high-precision radial positioning, eliminating potential misalignment during assembly and ensuring all modules quickly and accurately reach their theoretically designed positions. This guarantees the continuity and accuracy of the mold surface after assembly. The bolt connection provides strong and adjustable axial clamping force, firmly connecting the individual inserts into a rigid, integrated structure. This effectively resists mechanical and thermal stresses generated during subsequent laying, molding, and curing processes, preventing the mold itself from fretting or deforming due to external forces or heat, thus providing structural protection for the stability of the core molding surface. This connection method is detachable, allowing for the assembly of large or... Complex molds can be modularly disassembled for transportation and storage, and quickly and accurately assembled on-site. When local inserts wear out or need replacement, only the specific module can be disassembled and maintained without replacing the entire mold, significantly reducing maintenance and time costs and improving mold lifespan and economy. The combination of locating pins and bolts ensures high consistency and reproducibility of the geometry of each mold set and each reassembly, which is a prerequisite for stable production processes and the manufacture of products with small dimensional deviations and uniform quality, reducing product quality risks caused by mold assembly fluctuations.

[0028] In this embodiment, the shaping adhesive used in step S100 is CRT-77, and the thermal expansion silicone soft mold includes an outer silicone plate 4 and an inner silicone plate 5. The bonding process in step S100 is as follows: CRT-77 shaping adhesive is applied to the contact surfaces of the outer silicone plate 4, the inner silicone plate 5, the outer mold 1, and the inner mold 2, respectively. The outer silicone plate 4 and the inner silicone plate 5 are then bonded to the outer mold 1 and the inner mold 2, respectively. Then, CRT-77 shaping adhesive is applied to the outer side of the outer silicone plate 4 and the inner silicone plate 5 along the axial direction, and the pressure equalizing plate is bonded to the outer side of the outer silicone plate 4 and the inner silicone plate 5, respectively.

[0029] In this embodiment, the prepreg laying in steps S400 and S600 is carried out on a compaction fixture. Each layer is compacted with a plastic scraper and vacuum sealing compaction is performed during the process. The prepreg laying uses epoxy resin carbon fiber unidirectional tape, and is laid in combination of 0°, +45°, -45° and 90° laying angles respectively. The process involves compaction using a compaction fixture, with each layer compacted using a plastic scraper. This effectively removes air introduced during the layup process and ensures initial tight adhesion between prepreg layers and between the prepreg and the mold surface. Simultaneously, vacuum sealing compaction is employed throughout the process, further applying uniform negative pressure and continuously compressing the preform. This significantly reduces interlayer gaps and potential voids, providing a preform with high initial density and uniform structure for subsequent curing pressure application. This fundamentally reduces the risk of porosity and delamination defects. A layup combination including 0°, +45°, -45°, and 90° is used. The 0° layer primarily bears axial loads, providing the main strength and stiffness, while the ±45° layers work together to primarily resist shear. By reducing shear and torsional stresses and improving structural toughness, while 90° layers provide lateral support, balancing performance and preventing delamination propagation, this multi-directional synergistic layup strategy enables the final lattice reinforced frame to withstand complex loads from different directions. This avoids the weak-direction problem of anisotropic materials, significantly improving the reliability and damage tolerance of the structure during use. Laying is performed on specialized tooling and using specific tools (plastic scrapers) and intermediate processes (vacuum compaction), standardizing and regulating the laying process, reducing reliance on individual operator experience, minimizing quality fluctuations caused by human factors, and ensuring a high degree of consistency in the state of each layer of prepreg, thereby achieving the stability and predictability of the final product performance.

[0030] In this embodiment, the mold closing in step S400 specifically involves: using the side ejector rod 3 to push the outer mold 1 to a preset position, and then using locating pins and bolts to secure it. The locating pins are used to fix the upper cover plate 7 to the inner mold 2 and the outer mold 1. After fixing the position, the bolts are used to tighten them. After all the bolts are tightened, all mold closing gaps must be measured to be less than 0.1mm. After completing the above operations, the locating pins are removed. The mold closing in step S600 adopts the same mold closing process as in step S400. Using the side ejector rod 3 to accurately push the outer mold 1 to the preset position, and using the sequence of fixing with locating pins first and then tightening bolts, can effectively avoid misalignment or displacement during the mold closing process. The locating pins first provide accurate radial positioning and alignment, ensuring that each mold component is in the correct relative position. Subsequently, the bolt tightening provides a strong and controllable axial locking force, rigidly connecting the entire mold into a stable whole, thereby jointly ensuring that the mold maintains extremely high structural stability and surface accuracy when subjected to internal pressure and temperature changes. Controlling the gap to less than 0.1mm provides a direct and crucial evaluation standard for ensuring product dimensional accuracy and internal quality, making the mold closing quality measurable and verifiable. Strict control of the mold closing gap effectively prevents resin from being squeezed out of excessively large gaps during subsequent curing (i.e., "resin leakage"), thus avoiding defects such as material loss, localized resin deficiency, or resin excess. A tight mold closing state ensures that the mold cavity dimensions are accurately reproduced on the composite material product, thereby achieving precise control of the product's dimensional tolerances. Using the same mold closing process (S600 uses the same process as S400), and introducing positioning elements, tightening sequence, and a final quality inspection standard (measuring the gap), the mold closing process is transformed into a standardized and repeatable operation. This significantly reduces reliance on the operator's personal experience and skills, minimizes quality fluctuations caused by human factors, and ensures a high degree of consistency in the mold closing state across different batches and produced by different operators, thereby achieving stability in the final product performance and a high yield rate.

[0031] In this embodiment, the filling of the mold gap in step S300 specifically involves filling the rounded corner gap and triangular area of ​​the mold gap between the outer mold 1 and the inner mold 2 with carbon twisted yarn until it is slightly higher than the end face of the outer mold 1 and the end face of the inner mold 2. The filling requires first measuring the mold gap, then pre-impregnating the yarn, and performing quantitative filling to ensure that there are no material shortages or overflows in the mold gap area. After the mold is closed, the gaps between the lower base plate 8 and the inner mold 2 and the outer mold 1, especially the rounded corners and triangular areas, are complex in shape and difficult to seal. Using malleable carbon twisted yarn (usually carbon fiber pre-impregnated yarn bundles) for filling can perfectly fit these irregular gaps, forming an effective physical barrier. This filling method ensures that the entire mold cavity maintains a high degree of sealing during subsequent vacuum treatment and curing. This step requires measuring the gap before quantitative filling, until it is slightly higher than the end face. This measurement-estimation-filling process enables precise control of the filler amount. Insufficient filling (insufficient material) will lead to poor sealing, becoming a channel for resin loss or being punctured under pressure, resulting in localized resin deficiency or porosity. Excessive filling (overfill) may cause excess carbon twisted fibers to be squeezed into the product cavity, contaminating the product surface or changing the local fiber volume fraction, or even forming foreign matter defects. Quantitative filling fundamentally avoids both of these situations. The carbon twisted fibers are similar in material to the main prepreg, with good thermal expansion characteristics and chemical compatibility. Using carbon twisted fibers for filling, rather than other non-structural sealing materials, ensures that the area deforms and cures in coordination with the main structure during the curing process, avoiding internal stress or interface defects caused by material incompatibility. It also prevents foreign materials from accidentally mixing into the main body of the product, ensuring the purity of the product's fiber structure and the reliability of its performance.

[0032] The I-shaped cross-section grid beam composite material reinforcing frame of this embodiment is prepared using the molding method described above for the I-shaped cross-section grid beam composite material reinforcing frame.

[0033] In practice, a structural form of a thermal expansion transfer molding die is provided to solve the problems of complex molding and low yield of composite material reinforced frames with I-beam cross-sections. The main idea is to add a thermally expandable silicone rubber soft mold and a pressure equalizing plate to the molding surface of the steel mold. The pressure is evenly transferred by the principle of thermal expansion of the silicone rubber under heat. At the same time, due to the high expansion coefficient of this material, the cavity size at room temperature is larger than that of a pure steel mold, and normal mold closing can be achieved at room temperature. Theoretically, by adjusting the size of the thermally expandable silicone rubber and the cavity size of the steel mold, the appearance and internal quality of the product can be effectively guaranteed, thereby improving the yield of the manufactured parts.

[0034] The molding die for the composite reinforcement frame of the I-shaped cross-section grid beam, which is formed by co-curing thermally expandable silicone rubber with steel mold, consists of an outer mold 1, an inner mold 2, a side push rod 3, an outer silicone plate 4, an inner silicone plate 5, an upper silicone plate 6, an upper cover plate 7, a lower bottom plate 8, a bottom silicone plate 9, and standard parts. Among them, the outer mold 1, the inner mold 2, the side push rod 3, the upper cover plate 7, and the lower bottom plate 8 are made of Q235 steel, and the remaining silicone is a variable gradient composite elastic layer made of modified thermally expandable silicone rubber.

[0035] The molding method for the composite material reinforced frame of the I-shaped cross-section grid beam includes the following molding steps: Step 1: Determine the molding die components: Prepare the outer mold 1, inner mold 2, side ejector pin 3, outer silicone plate 4, inner silicone plate 5, upper silicone plate 6, upper cover plate 7, lower base plate 8, base plate silicone plate 9, and standard parts; Step 2: Assembly of inner mold 2: Arrange the inserts on the work surface according to their numbering order, and then press the inner mold 2... Figure 1 As shown, assemble the inner mold 2; Step 3: Applying the silicone plate: Apply CRT-77 shaping adhesive to the contact surfaces of the outer silicone plate 4, the inner silicone plate 5 and the steel mold, and then bond them to the outer mold 1 and the inner mold 2 respectively. Then apply CRT-77 shaping adhesive to the outside of the thermal expansion silicone soft template and bond the pressure equalizing plate to the thermal expansion silicone soft template. Step 4: Laying the tiles: After completing step three, carbon fiber prepreg is laid on the pressure plates on both sides of the outer mold 1 and the inner mold 2. Vacuum sealing and compaction are required during the process until the product reaches the required theoretical size. Step 5: Mold Closing Place the base silicone plate 9 on the bottom base plate 8, and press the outer mold 1 and inner mold 2 together. Figure 1 and Figure 2 The side ejector pins 3 are used to close the mold sequentially. Step Six: Fill in the blanks. Fill the rounded gap and triangular area of ​​the mold joint between the outer mold 1 and the inner mold 2 with carbon twisted wire until it is slightly higher than the end faces of the outer mold 1 and the inner mold 2. Step 7, Laying: After completing step six, prepreg is laid on the end faces of the outer mold 1 and the inner mold 2 to form an I-beam preform; Step 8: Mold Closing Place the upper silicone plate 6 and the upper cover plate 7 on the completed I-beam preform and close the mold. Step 9: Demolding After completing step eight, flip the mold over to remove the bottom plate 8 and take out the bottom plate silicone plate 9; Step 10, Laying: Repeat step seven to lay prepreg on the other end face of the outer mold 1 and the inner mold 2 to form an I-beam preform; Step 11: Mold Closing Place the base silicone plate 9 and the lower base plate 8 on the completed I-beam preform and close the mold. Step 12, Curing: The molded mold is placed in an oven for heating and curing. Step 13: Demolding The mold is disassembled according to the component structure to obtain an I-shaped cross-section reinforcing frame.

[0036] The molding die in step one is a composite mold structure of thermally expandable silicone rubber and steel mold.

[0037] In step two, the assembly process ensures dimensional accuracy through locating pin holes, and then the components are connected using bolts.

[0038] The thermal expansion silicone soft template (silicone core mold) in step three is made of a flexible, high-temperature resistant silicone rubber material with an excellent coefficient of thermal expansion.

[0039] In step four, the prepreg is laid on a compaction fixture. To ensure that the prepreg is compacted during the laying process, each layer is compacted with a plastic scraper. Vacuum sealing and compaction treatment is required during the process. The prepreg layers are made of epoxy resin carbon fiber unidirectional tape, in combinations of 0°, +45°, -45° and 90°.

[0040] In step five, the mold closing requires using the side ejector rod 3 to push the outer mold 1 to its final position and then securing it with locating pins and bolts.

[0041] In step six, the filling process requires first measuring the mold joint and then filling it with prepreg yarn to ensure that there is no material shortage or overflow in the mold joint area.

[0042] In step seven, after each layer of prepreg is laid, it is compacted with a scraper. Vacuuming is required during the process to pre-compact the product.

[0043] In step eight, the mold closing requires using locating pins to fix the upper cover plate 7 to the inner mold 2 and the outer mold 1. After fixing the position, use bolts to tighten them. After all the bolts are tightened, all mold closing gaps must be measured to be less than 0.1mm. After completing the above operations, the locating pins can be removed.

[0044] In step nine, the mold is disassembled by using a crane to flip the mold, removing all the bolts on the lower base plate 8, and taking off the lower base plate 8.

[0045] The tiling process in step ten is the same as that in step seven.

[0046] The mold-closing procedure in step eleven is the same as that in step eight.

[0047] In step twelve, the drying oven heating and curing relies on steel molds to ensure the external dimensions. The thermally expanding silicone rubber expands and is pressurized by heat, thereby ensuring that the product is evenly pressurized and thus preventing defects from appearing on the internal surface of the product.

[0048] The various metal materials mentioned in this invention can be replaced with mold steel of other specifications and models. The mold size needs to be calculated and scaled according to the actual material expansion coefficient.

[0049] The expansion core used in the thermal expansion silicone rubber mentioned in this invention is a common material on the market and can be replaced by similar expansion cores or similar functional materials.

[0050] The method mentioned in this invention can design the mold structure and the size of the thermally expanded silicone rubber according to the product size and shape, thereby producing I-shaped cross-section products of various shapes.

[0051] Compared with traditional technologies, the present invention has the following advantages: 1. The thermally expandable silicone rubber mentioned in this invention expands under heat and pressure to ensure that the product is subjected to pressure evenly, so as not to cause defects in the inner surface of the product, and to improve the speed during the mold closing process, thereby increasing the yield rate.

[0052] 2. The oven heating and curing method mentioned in this invention replaces autoclave molding, reducing curing time and eliminating the auxiliary materials required for autoclave molding, thereby reducing the production cost of the product.

[0053] 3. The products prepared by the molding process used in this invention are obtained through a closed mold, resulting in high surface quality. The selected resin has low viscosity, a long operating window, is easy to operate, and exhibits excellent processability. Furthermore, the molded products demonstrate high quality stability.

[0054] Matters not covered in this invention are common knowledge.

[0055] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0056] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A molding method for an I-shaped cross-section composite material reinforcing frame, comprising an I-shaped cross-section composite material reinforcing frame molding mold, consisting of an outer mold (1), an inner mold (2), a side push rod (3), an outer silicone plate (4), an inner silicone plate (5), an upper silicone plate (6), an upper cover plate (7), a lower bottom plate (8), a bottom silicone plate (9), and standard parts; the inner mold (2), inner silicone plate (5), outer silicone plate (4), and outer mold (1) are arranged radially from the inside to the outside; the upper silicone plate (6) and the upper cover plate (7) are sequentially molded onto the upper end faces of the outer mold (1) and the inner mold (2); the bottom silicone plate (9) and the lower bottom plate (8) are sequentially molded onto the lower end faces of the outer mold (1) and the inner mold (2), and are fixed by the side push rod (3); the standard parts are temporarily placed in the cavity of the mold for testing; Its features are, Includes the following steps: S100. Assemble the inner mold. Along the radial direction of the inner mold (2), bond the thermal expansion silicone soft mold to the inner mold and the outer mold (1) in turn. Then bond the pressure equalizing plate to both ends of the thermal expansion silicone soft mold in the axial direction. Before bonding, apply shaping spray glue to the contact surfaces of the inner mold (2), the outer mold (1), the thermal expansion silicone soft mold and the pressure equalizing plate. S200. Carbon fiber prepreg is laid on the pressure plate on both sides of the outer mold (1) and the two sides of the inner mold. Vacuum sealing and compaction are carried out during the process until the theoretical size required by the product is achieved. S300. Place the base plate silicone plate (9) on the lower base plate (8), and use the side ejector rod (3) to sequentially close the lower base plate (8) with the lower end face of the inner mold (2) and the outer mold (1), and fill the mold gap. S400, the first I-beam preform is formed by laying prepreg on the upper surface of the outer mold (1) and the inner mold (2), and the upper silicone plate (6) and the upper cover plate (7) are placed on the first I-beam preform after laying and the mold is closed. S500, flip the mold and remove the bottom plate (8), and take out the silicone plate (9) from the bottom plate. S600, prepreg is laid from the lower end face of the outer mold (1) and the inner mold (2) to form the second I-beam preform. The bottom silicone plate (9) and the lower bottom plate (8) are placed on the completed second I-beam preform and the mold is closed. S700, after curing and demolding, a composite material reinforced frame with an I-shaped cross section grid beam is obtained.

2. The molding method of the composite material reinforcing frame of the I-shaped cross-section grid beam according to claim 1, characterized in that, The assembly of the inner mold in step S100 specifically involves: According to the component insert numbering sequence, the component inserts are laid on the worktable for the assembly of the inner mold (2).

3. The molding method of the composite material reinforcing frame of the I-shaped cross-section grid beam according to claim 2, characterized in that, Assembly ensures dimensional accuracy through locating pin holes and is connected by bolts.

4. The molding method of the composite material reinforcing frame of the I-shaped cross-section grid beam according to claim 1, characterized in that, The shaping adhesive used in step S100 is CRT-77, and the thermal expansion silicone soft mold includes an outer silicone plate (4) and an inner silicone plate (5). The pasting process in step S100 is as follows: Apply CRT-77 shaping spray adhesive to the contact surfaces of the outer silicone plate (4), inner silicone plate (5), outer mold (1), and inner mold (2), respectively. Bond the outer silicone plate (4) and inner silicone plate (5) to the outer mold (1) and inner mold (2), respectively. Then apply CRT-77 shaping spray adhesive to the outer side of the outer silicone plate (4) and inner silicone plate (5) along the axial direction, and bond the equalizing plate to the outer side of the outer silicone plate (4) and inner silicone plate (5), respectively.

5. The molding method of the composite material reinforcing frame of the I-shaped cross-section grid beam according to claim 1, characterized in that, In steps S400 and S600, the prepreg is laid in layers on a compaction fixture. Each layer is compacted with a plastic scraper and vacuum sealing compaction is performed during the process. The prepreg layup uses epoxy resin carbon fiber unidirectional tape, and is laid up in combinations of layup angles of 0°, +45°, -45° and 90°.

6. The molding method of the composite material reinforcing frame of the I-shaped cross-section grid beam according to claim 1, characterized in that, The mold closing in step S400 is specifically as follows: Use the side push rod (3) to push the outer mold (1) to the preset position, and use the positioning pin and bolt to tighten it. Use the positioning pin to fix the position of the upper cover plate (7) with the inner mold (2) and the outer mold (1). After fixing the position, use the bolt to tighten it. After all the bolts are tightened, all mold gaps must be measured to be less than 0.1mm. After completing the above operations, the positioning pin is removed. The mold closing process in step S600 is the same as that in step S400.

7. The molding method of the composite material reinforcing frame of the I-shaped cross-section grid beam according to any one of claims 1 to 6, characterized in that, The filling of the mold joint in step S300 specifically involves: Carbon twisted wire is filled into the rounded gap and triangular area of ​​the mold joint between the outer mold (1) and the inner mold (2) until it is slightly higher than the end face of the outer mold (1) and the end face of the inner mold (2). The filling process requires first measuring the mold joint gap, then pre-impregnating the yarn, and then quantitatively filling it to ensure that there are no material shortages or overflows in the mold joint area.

8. The molding method of the composite material reinforcing frame of the I-shaped cross-section grid beam according to any one of claims 1 to 6, characterized in that, The outer mold (1), inner mold (2), side ejector rod (3), upper cover plate (7) and lower base plate (8) are made of Q235 steel. The outer silicone plate (4), inner silicone plate (5), upper silicone plate (6) and bottom silicone plate (9) are made of modified thermal expansion silicone rubber or flexible high temperature resistant silicone rubber with excellent thermal expansion coefficient.

9. A composite material reinforced frame for an I-beam cross-section grid beam, characterized in that, The composite reinforcing frame with an I-shaped cross-section beam, as described in any one of claims 1 to 8, is prepared using the molding method of any composite material reinforcing frame with an I-shaped cross-section.

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