Barrel-shaped component with window rib structure and preparation method of barrel-shaped component

Abstract

The invention relates to a cylindrical part with a window rib structure and a preparation method of the cylindrical part, belongs to the technical field of composite materials, and solves the problems that in the prior art, a part with a window rib structure is poor in mechanical property, insufficient in bearing capacity, prone to deformation and collapse and the like. The invention provides a cylindrical component with a window rib structure, the component comprises a window frame, an extension part, ribs and a skin, and the extension part extends outwards along the window frame; the skin forms a cylindrical main body of the component, and the ribs and the window frame are arranged on the inner surface of the cylindrical component and are connected through the extension part; the part is integrally formed through the RTM technology. The component is reasonable in design, connection at the joints is firm, the window frame, the ribs and the skin form an integrated framework to form a common bearing structure, the structural strength and the bearing performance of the window rib structure component are greatly improved, and the tensile strength is larger than or equal to 310 MPa.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, and in particular to a cylindrical component with a window rib structure and its preparation method. Background Technology

[0002] Resin-based composite materials are made by combining reinforcing fibers with resin. They possess high specific stiffness, specific strength, and corrosion resistance, and are widely used in the aerospace field for primary load-bearing components such as wing surfaces and cabin structures. To ensure multifunctional integration in structural components, resin-based composite materials require the installation of functional components on the structural parts. Therefore, mounting platforms or mounting frames are needed in the structure.

[0003] To achieve the installation function, the conventional method is to first prepare a structure such as an installation platform, then make openings in the skin of the composite component, and use adhesive bonding, riveting, or a combination of methods to install the installation platform onto the composite component in the opening area for installing other parts. However, openings in pre-formed structural components and using riveting to install the platform has two drawbacks. First, it cuts the fibers, damaging the overall structure of the composite material and leading to a decrease in structural performance. Second, using adhesive riveting fails to utilize the continuous reinforcement function of the reinforcing fibers, resulting in weak mechanical properties at the assembly point.

[0004] In summary, existing resin-based composite material components, especially complex components with window rib structures, generally suffer from insufficient structural strength, poor load-bearing performance, and difficulties in integrating existing pretreatment / preforming processes with RTM processes. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to provide a cylindrical component with a window rib structure to solve at least one of the following problems commonly found in existing resin-based composite material components, especially complex components with window rib structures: insufficient structural strength, poor load-bearing performance, and susceptibility to deformation and collapse; and proposes a new pretreatment / preforming process to enable the component to meet the preparation requirements of the RTM process, thereby further improving the quality and performance of the product.

[0006] The present invention provides a cylindrical component with a window rib structure. The component includes a window frame 5, an extension 4, ribs 2 and a skin 3. The extension 4 extends outward along the window frame 5, and the extension 4 and the window frame 5 have a continuous fiber structure.

[0007] The skin 3 forms the cylindrical body of the component, and the ribs 2 and window frame 5 are disposed on the inner surface of the cylindrical component and connected by the extension 4.

[0008] The component is integrally molded using RTM technology.

[0009] Specifically, the window is a triangle, square, rectangle or other irregular polygon; the shape of the window frame 5 matches the shape of the window.

[0010] Specifically, the number of extensions 4 is not less than 3; the ribs 2 are annular ribs arranged along the circumferential direction and / or strip ribs arranged along the axial direction, and the number of ribs 2 is not less than 2.

[0011] Specifically, the window frame 5 and the extension 4 are made of prepreg; the ribs 2 and the skin 3 are made of fiber fabric.

[0012] The present invention also discloses a method for preparing the cylindrical component, specifically including the following steps:

[0013] S1: Based on the component structure, perform parting design and prepare in advance the skin 3, ribs 2, prepreg, pre-compacting mold and component molding mold;

[0014] S2: Prepreg is used to cross-lay out the window frame preform 1 according to the parting design in the female mold of the pre-compacting mold. The window frame 5 is located inside the pre-compacting mold, and the extension 4 is located outside the pre-compacting mold.

[0015] S3: After the layup is completed, the temperature is increased and the pressure is applied to close the mold and pre-compact it. The window frame 5 is pre-compacted, while the extension 4 is not pre-compacted. During the pre-compacting process, the extension 4 is cooled down. After cooling and demolding, the pre-compacted window frame preform 1 is obtained.

[0016] S4: Lay up the skin 3, window frame preform 1, and rib 2 in the negative mold of the component forming mold according to the parting design, and overlap the extension 4 of the window frame preform 1 with the rib 2.

[0017] S5: After mold closing, RTM injection, temperature curing, and demolding, an integrally formed structure with window ribs can be obtained.

[0018] Specifically, the parting design process in step S1 is as follows: the parting design is carried out according to the overall shape of the window rib structure component, and the overall structure is divided into three parts: window frame preform 1, rib 2 and skin 3. The window frame preform 1 includes a window frame 5 and an extension 4 extending outward along the window frame 5. The extension 4 is used to connect the window frame preform 1 and the rib 2.

[0019] Specifically, in step S2, during the cross-laying of the prepreg, the stacked portion is laid out using a cross-cutting method.

[0020] The cross-cut ply includes cut-off layers and non-cut-off layers;

[0021] The cut-off layer refers to cutting off the weft-direction prepreg and inserting the warp-direction prepreg into the middle of the cut-off weft-direction prepreg, with the end face of the cut-off weft-direction prepreg connected to the two side edges of the warp-direction prepreg.

[0022] The non-cut-off layer refers to the prepreg in the warp direction being cut to a suitable size during laying, with the end face of the prepreg in the warp direction connected to the edge of the prepreg in the weft direction during laying, and the prepreg in the weft direction not needing to be cut off.

[0023] The cut-off layers and non-cut-off layers are arranged at adjacent intervals.

[0024] Specifically, in step S4, the overlapping portion of the rib 2 and the extension 4 is laid up using a stacked and truncated method;

[0025] The stacked truncated layup includes inserted layers and non-inserted layers;

[0026] The insertion layer refers to cutting off the rib 2, inserting the extension 4 into the middle of the cut-off rib 2, connecting the end face of the cut-off rib 2 with the two side edges of the extension 4, and cutting off the excess part of the extension 4.

[0027] The non-insertion layer refers to cutting the extension 4 to a suitable size, so that when laying it, the end face of the extension 4 is connected to the edge of the rib 2, and the rib 2 does not need to be cut off;

[0028] The inserted layers account for 25% to 75% of the total number of layers in the stacked portion, and the total number of layers in the stacked portion = the number of inserted layers + the number of non-inserted layers.

[0029] Specifically, when the rib 2 is an annular rib, during the layup process in step S4, the joint of the rib 2 is cut and a toothed structure with interlocking is used for layup to form a complete annular rib.

[0030] Specifically, after the layup is completed in step S4, the extension 4 and the overlapping part of the extension 4 and the rib 2 are subjected to hot pressing pretreatment so that the dimensions of the extension 4 and the overlapping part reach the preset net dimensions.

[0031] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0032] 1. The present invention provides a cylindrical component with a window rib structure, which differs from the window setting method of the prior art. It creatively designs an extension with a continuous fiber structure with the window frame. The two are integrated from the initial state and are connected together by the extension through overlapping and laying. Subsequently, the window frame, extension, rib and even skin are integrally formed by the RTM process, so that the window frame, extension, rib and skin form an integrated configuration. In particular, the window frame, extension and rib together form an integral frame structure, which significantly improves the structural strength and load-bearing performance, so that the component can give full play to the role of the installation platform and better realize the load-bearing function.

[0033] 2. The present invention also designs a pretreatment / preforming process that combines a "pre-compacted part + non-pre-compacted part", so that the component meets the strict requirements of the RTM process for the size of the process part, and the final product has good integrity and significantly improved overall performance.

[0034] This invention differs from existing window preforming processes by creatively reserving an extension for connection with ribs during the preforming process. Furthermore, pre-compacting of the window frame is only performed during the pre-compacting step, omitting the extension. The pre-compacting of the window frame serves two main purposes: firstly, it ensures the window frame meets the dimensional requirements of the RTM process, which demands that the dimensions of the process part before mold closing be as close as possible to the preset net dimensions to avoid damaging the mold and affecting product quality; secondly, the pre-compacted window frame preform reduces or even eliminates interlayer slippage and wrinkling of the prepreg during subsequent component molding mold layup, thus optimizing the layup effect.

[0035] The uncompacted extension can be interleaved with the ribs (generally referring to fiber fabric, preferably dry carbon cloth) to ensure a stable connection between the two after subsequent molding, especially when using the stacked cut-off layup proposed in this invention. In reality, because the extension is not pre-compacted, its thickness differs significantly from the net size. To better meet the dimensional requirements of the RTM process, pre-treatment can be performed after layup using an iron or hot air blower. This allows excess adhesive from the extension to enter the ribs (dry carbon cloth) surrounding the overlapping portion of the extension. This achieves dimensional compression, bringing it closer to the preset net size, and also makes the connection between the extension and the ribs more stable, avoiding or reducing wrinkles and misalignments in the overlapping fiber fabric (dry carbon cloth).

[0036] Ultimately, the component formed by the RTM process is an integrated structure. The window frame, extension, and ribs together form a unified frame structure, which greatly improves the structural strength and load-bearing capacity and reduces the risk of localized damage. Specific testing shows that the isotropic integrated component prepared using this method has an isotropic tensile strength ≥310 MPa.

[0037] 3. The window-ribbed structural component provided by this invention has a good combination effect between the extension and the rib. In step S4, the overlapping part of the rib and the extension is laid up using a stacked cut-off method; the stacked cut-off method includes an insert layer and a non-insertion layer; the insert layer refers to cutting off the rib, inserting the extension into the middle of the cut rib, connecting the end face of the cut rib to the two side edges of the extension, and cutting off the excess part of the extension; the non-insertion layer refers to cutting the extension to a suitable size, connecting the end face of the extension to the edge of the rib during laying, and the rib does not need to be cut off.

[0038] The inserted layer mainly provides tensile strength along the extension direction, while the non-inserted layer mainly provides tensile strength along the rib extension direction. By stacking the inserted and non-inserted layers alternately (without strict requirements on the adjacent spacing), the connection between the extension and the rib is very stable and has good mechanical properties after being formed by the RTM process.

[0039] The inserted layer accounts for 25% to 75% of the total number of layers in the stacked part, and the total number of layers in the stacked part = the number of inserted layers + the number of non-inserted layers; the proportion of the inserted layer should not be too high or too low, otherwise it may lead to a significant decrease in the mechanical properties in a certain direction, which in turn leads to a decrease in the overall structural strength.

[0040] 4. The molding method provided by this invention has simple steps, mild process conditions, and relatively readily available equipment and molds. It can be produced or prepared using existing technologies, and the operation difficulty is moderate, making it suitable for factory production and large-scale promotion. The RTM process for integral molding of window rib structures provided by this invention has good processability and operability. Especially when an opening needs to be temporarily added after the product design is completed, this method can effectively strengthen the structure at the opening area.

[0041] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0042] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0043] Figure 1 A process flow diagram of a method for integral molding of a windowed ribbed structure using RTM technology;

[0044] Figure 2 This is a schematic diagram of the cylindrical component with window rib structure in Example 1;

[0045] Figure 3 This is a plan view of the window frame preform in Example 1;

[0046] Figure 4 This is a schematic diagram of a cross-cut ply;

[0047] Figure 5 This is a schematic diagram of a stacked truncated layer layout (with the inserted layer accounting for 50%).

[0048] Figure 6 This is a schematic diagram of the embedded layer at the interface of the annular rib.

[0049] Figure label:

[0050] 1. Window frame preform; 2. Ribs; 3. Skin; 4. Extension; 5. Window frame. Detailed Implementation

[0051] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0052] Analysis of existing technological defects:

[0053] Existing resin-based composite material components, especially complex components with window rib structures, generally suffer from insufficient structural strength and poor load-bearing capacity, resulting in poor performance as load-bearing platforms and difficulty in meeting the needs of special applications. These problems are particularly pronounced for components with complex structures such as rotating bodies and irregular curved surfaces.

[0054] Possible solutions:

[0055] Resin transfer molding (RTM) is a process technology that involves flowing liquid resin into a closed mold, impregnating reinforcing materials, and then curing it to form a finished product. It falls under the category of liquid molding or structural liquid molding technologies for composite materials. RTM is suitable for various reinforcing materials, such as glass fiber and carbon fiber, and can produce large-sized, complex, and high-strength composite parts. It has been widely used in aerospace, automotive, shipbuilding, and construction industries.

[0056] New technical challenges:

[0057] However, the RTM process requires liquid resin to flow within a closed mold, thus imposing strict requirements on the dimensions of process parts, especially those before mold closing. These dimensions must be as close as possible to the final net dimensions; otherwise, mold damage, inability to close the mold, and uncontrollable product quality may occur. However, in existing processes, the net dimensions of resin-based composite parts differ significantly from the final product's net dimensions, making it difficult to meet the requirements of the RTM process.

[0058] The present invention provides a cylindrical component with a window rib structure. The component includes a window frame, an extension, ribs, and a skin. The extension extends outward along the window frame, and the extension and the window frame have a continuous fiber structure.

[0059] The skin forms the cylindrical body of the component, and the ribs and window frame are disposed on the inner surface of the cylindrical component and connected by the extension;

[0060] The component is integrally molded using RTM technology.

[0061] This invention provides a cylindrical component with a window rib structure, which differs from the window setting method of the prior art. It creatively designs an extension with a continuous fiber structure with the window frame, so that the two are integrated from the initial state. The window frame and the rib are connected together by the extension through overlapping and laying. Subsequently, the component is integrally formed by RTM process, so that the window frame, extension, rib and even skin form an integrated configuration. In particular, the window frame, extension and rib together form an integral frame structure, which significantly improves the structural strength and load-bearing performance, so that the component can fully play the role of the installation platform and better realize the load-bearing function.

[0062] Specifically, the window is a triangle, square, rectangle, or other irregular polygon; the shape of the window frame matches the shape of the window.

[0063] Specifically, the number of extensions is no less than three. The number of extensions is closely related to the number of windows. For example, triangular windows preferably have three or six extensions, square or rectangular windows preferably have four or eight extensions, and so on. N-sided windows preferably have N or 2N extensions. In practice, the number of extensions can be any integer greater than or equal to three, but the above-mentioned preferred schemes are more conducive to improving the stability and load-bearing capacity of the frame.

[0064] The ribs are annular ribs arranged along the circumferential direction and / or strip ribs arranged along the axial direction, and the number of ribs is not less than two. Preferably, for cylindrical components, annular ribs have a more significant effect on improving strength, while strip ribs mainly play an auxiliary role. Therefore, the arrangement of "annular ribs + strip ribs" or "annular ribs" is preferred.

[0065] Specifically, the window frame and extension are made of prepreg; the ribs and skin are made of fibrous fabric.

[0066] The present invention also provides a method for preparing the cylindrical component:

[0067] First, the overall structure is divided into three parts based on the overall shape of the window frame rib structure component: window frame preform, rib, and skin. The window frame preform includes a window frame and an extension extending outward along the window frame. The extension is used to connect the window frame preform to the rib.

[0068] Then, a preformed window frame is prepared using prepreg according to the parting design, and the window frame is pre-compacted using a pre-compacting mold, while the extension is not pre-compacted, to obtain a pre-compacted window frame preform.

[0069] The skin, window frame preform, and ribs are laid up in the mold for component forming according to the parting design. The extension of the window frame preform is laid up with the ribs. After the layup is completed, the RTM process is used to form the window rib structure.

[0070] The RTM process provided by this invention produces an integral component with a window rib structure. The window portion, through extensions and ribs, forms an overall frame structure, significantly improving structural strength and load-bearing capacity. This allows the component to fully function as an installation platform and better fulfill its load-bearing function. Furthermore, by designing a pre-treatment / pre-forming process that combines a pre-compacted portion with a non-pre-compacted portion, the component meets the stringent dimensional requirements of the RTM process, resulting in a product with good overall integrity and significantly improved comprehensive performance.

[0071] In the prior art, components containing window rib structures are generally manufactured using two methods:

[0072] One method involves directly cutting the window onto the molded part. The window has no frame structure, or the frame structure is subsequently installed through bonding / riveting. This method results in the fibers inside the molded part being cut, altering the mechanical characteristics at the fiber cuts, compromising the overall mechanical stability of the material, and reducing its load-bearing capacity. It is worth noting that pre-cutting or prefabricating the window before integral molding the component does not result in a loss of mechanical properties due to fiber breakage, because the fibers already have cuts during the molding process, thus preventing tensile stress at the cuts.

[0073] The second method is to prefabricate the window frame before manufacturing the components. Although this method avoids the problem of decreased mechanical properties caused by fiber breakage, the mechanical properties of the product are still poor because the window frame and the rib structure are independent of each other. In addition, there are problems such as irregular deformation, uneven mechanical properties in all directions, and poor overall load-bearing capacity, making it unreliable as a load-bearing platform.

[0074] This invention differs from existing window preforming processes by creatively reserving an extension for connection with ribs during the preforming process. Furthermore, pre-compacting of the window frame is only performed during the pre-compacting step, omitting the extension. The pre-compacting of the window frame serves two main purposes: firstly, it ensures the window frame meets the dimensional requirements of the RTM process, which demands that the dimensions of the process part before mold closing be as close as possible to the preset net dimensions to avoid damaging the mold and affecting product quality; secondly, the pre-compacted window frame (preform) reduces or even eliminates interlayer slippage and wrinkling of the prepreg during subsequent component molding mold layup, thus improving the layup effect.

[0075] It is worth noting that the number of extensions can be adjusted according to the window shape and the number of ribs. For example, in the designs of embodiments 1 to 5, there are 4 extensions and 2 ribs. In actual implementation, there can be 8 extensions (grid-shaped design) and 4 ribs. When the window is a more complex shape such as a triangle, an irregular polygon, or even a twisted body of revolution, the number of extensions and ribs can be further increased to meet the performance requirements in actual implementation.

[0076] The uncompacted extension can be interleaved with the ribs (generally referring to fiber fabric, preferably dry carbon cloth) to ensure a stable connection between the two after subsequent molding, especially when using the stacked cut-off layup proposed in this invention. In reality, because the extension is not pre-compacted, its thickness differs significantly from the net size. To better meet the dimensional requirements of the RTM process, pre-treatment can be performed after layup using an iron or hot air blower. This allows excess adhesive from the extension to enter the ribs (dry carbon cloth) surrounding the stacked portion. This achieves dimensional compression, bringing it closer to the preset net size, and also makes the connection between the extension and the ribs more stable, avoiding or reducing wrinkles and misalignments in the stacked dry carbon cloth.

[0077] Ultimately, the components formed by the RTM process are an integrated structure, with the window frame, extension, and ribs forming a unified frame structure, which greatly improves the structural strength and load-bearing capacity and reduces the risk of local damage.

[0078] The method includes the following steps:

[0079] S1: Based on the component structure, perform parting design and prepare skin, ribs, prepreg, pre-compacted mold and component molding mold in advance;

[0080] S2: Prepreg is used to cross-lay out a window frame preform according to the parting design in the female mold of the precompacting mold. The window frame is located inside the precompacting mold and the extension is located outside the precompacting mold.

[0081] S3: After the layup is completed, the temperature and pressure are increased, the mold is closed, and pre-compaction is performed. During the pre-compaction process, the extension is cooled down. After cooling and demolding, the pre-compacted window frame preform is obtained.

[0082] S4: Lay out the skin, window frame preform, and ribs in the female mold of the component forming mold according to the parting design, and lay out the extension of the window frame preform and the ribs overlapping.

[0083] S5: After mold closing, RTM injection, temperature curing, and demolding, an integrally formed structure with window ribs can be obtained.

[0084] Specifically, the skin and ribs are made of fiber fabric, preferably dry carbon cloth; the prepreg is a fabric prepreg or a unidirectional prepreg. The unidirectional prepreg can be cut according to the pre-compacted part layup pattern and then laid up in the pre-compacted mold in a specified angle sequence.

[0085] Preferably, the prepreg is a dry-process prepreg. Dry-process prepregs do not involve solvents during production, resulting in relatively low volatile component content, uniform adhesive content, and moderate viscosity, making them suitable for lay-up and beneficial for improving the mechanical properties of window frames, window frame preforms, and even the entire component.

[0086] Specifically, the pre-compacting mold and the mold used for component forming must be thoroughly cleaned to ensure that their inner surfaces are smooth, free of oil stains, impurities, and protruding adhesive particles. If necessary, metallographic sandpaper can be used for polishing.

[0087] Preferably, the pre-compacting mold is a metal mold, and the metal mold needs to be coated with a release agent layer. When applying the release agent, it should be evenly applied to the mold surface area to avoid the mold and preform sticking together during the pre-compacting process, which could lead to product damage.

[0088] Specifically, the outer surface of the mold used for forming the component is preferably a metal mold, while the inner surface can be made using either a rigid or flexible mold, depending on the required technical precision. Both rigid and flexible molds must be evenly coated with release wax, ensuring no areas are missed.

[0089] It is worth noting that rigid molds are beneficial for improving the precision and stability of products, but they have more stringent requirements for the dimensions of process parts; flexible molds have lower requirements for the dimensions of process parts, but at the same time, the precision and stability of the products are slightly reduced.

[0090] Preferably, when the rib thickness d ≤ 5mm, the inner surface of the mold for forming the part is a metal mold; when the rib thickness is low, the dimensions of the process part are more likely to approach the net dimensions, which can meet the requirements for the use of metal molds (rigid molds);

[0091] When the rib thickness d > 5mm, the inner surface of the mold used for part forming is a soft mold or a metal mold. When the rib thickness is high, the difference between the process part size and the net size is relatively large, and the flexible mold is more suitable. When a metal mold is used, several vacuum pre-absorption treatments are required during lay-up and / or before mold closing to ensure that the process part meets the usage requirements of the metal mold (rigid mold) as much as possible.

[0092] Specifically, in step S2, after each layer of prepreg is laid, the extension portion is wrapped with a release cloth 1-2 times. The release cloth is preferably a double-sided non-adhesive release cloth. After wrapping the extension area of ​​each prepreg layer with the release cloth, it is secured with tape. This step further prevents the extension portion from sticking together, ensuring that even if some of the adhesive in the extension portion softens during pre-compaction, it will not stick to other layers.

[0093] Furthermore, in step S2, during the cross-laying process of the prepreg, the stacked portion is laid up using a cross-cutting method.

[0094] The cross-cut ply includes cut-off layers and non-cut-off layers;

[0095] The cut-off layer refers to cutting off the weft-direction prepreg and inserting the warp-direction prepreg into the middle of the cut-off weft-direction prepreg, with the end face of the cut-off weft-direction prepreg connected to the two side edges of the warp-direction prepreg.

[0096] The truncated layer is more conducive to preserving the longitudinal tensile strength;

[0097] The non-cut-off layer refers to the prepreg in the warp direction being cut to a suitable size during laying, with the end face of the prepreg in the warp direction connected to the edge of the prepreg in the weft direction during laying, and the prepreg in the weft direction not needing to be cut off.

[0098] The truncated layer is more conducive to preserving the tensile strength in the latitudinal direction;

[0099] The adjacent spacing between the cut-off layer and the non-cut-off layer is most beneficial for balancing the mechanical properties in the warp and weft directions, since window frames are generally required to be isotropic.

[0100] Furthermore, when the ribs are annular ribs, during the layup process in step S4, the rib joints are trimmed and a toothed structure with interlocking is used for layup (e.g., Figure 6 As shown in the figure, a complete ring-shaped rib is formed.

[0101] Specifically, the pre-compaction temperature and pressure are adjusted according to the type of prepreg compound, ensuring that the prepreg is pre-compacted to the required net dimensions within the mold cavity while remaining uncured. It is worth noting that the heating temperature is a more critical indicator. If the temperature during pre-compaction is too high, irreversible thermosetting (resin forming a cross-linked structure) will occur, preventing the compound from properly liquefying, dissolving, and co-curing in subsequent steps, ultimately leading to the failure of the entire component fabrication. Generally, the heating temperature should be lower than the corresponding thermosetting initiation temperature (abbreviated as T). i ).

[0102] For example, the prepreg resin is one or more of room temperature epoxy resin, medium temperature epoxy resin, or high temperature epoxy resin. The resin has good miscibility, allowing for co-curing, and the final molded structure exhibits excellent strength.

[0103] For example, a common pre-compaction parameter is as follows: after the layup is completed, the mold is heated to 80-90°C and pressed to close the mold. After holding the mold at this temperature for 30-60 minutes, it is cooled to 30°C using a fan before demolding to prepare a preform for later use.

[0104] Preferably, in step S3, a fan is used to cool the extension section. The purpose of this operation is to prevent the prepreg from softening due to the residual heat escaping from the extension section, which could lead to interlayer bonding or curing.

[0105] Furthermore, in step S4, the overlapping portion of the ribs and extensions is laid up using a stacked and truncated method.

[0106] The stacked truncated layup includes inserted layers and non-inserted layers;

[0107] The insertion layer refers to cutting off the rib, inserting the extension into the middle of the cut rib, connecting the end face of the cut rib to the two side edges of the extension, and cutting off the excess part of the extension.

[0108] The non-insertion layer refers to the extension being cut to a suitable size, and when laid out, the end face of the extension is connected to the edge of the rib, without the rib needing to be cut off;

[0109] The inserted layer mainly provides tensile strength along the extension direction, while the non-inserted layer mainly provides tensile strength along the rib extension direction. By stacking the inserted and non-inserted layers alternately (without strict requirements on the adjacent spacing), the connection between the extension and the rib is very stable and has good mechanical properties after being formed by the RTM process.

[0110] The inserted layer accounts for 25% to 75% of the total number of layers in the stacked part, and the total number of layers in the stacked part = the number of inserted layers + the number of non-inserted layers; the proportion of the inserted layer should not be too high or too low, otherwise it may lead to a significant decrease in the mechanical properties in a certain direction, which in turn leads to a decrease in the overall structural strength.

[0111] Specifically, after the layup is completed in step S4, the extension portion and the overlapping portion of the extension portion and the ribs are subjected to hot-pressing pretreatment to ensure that the dimensions of the extension portion and the overlapping portion reach the preset net dimensions. In reality, because the extension portion is not pre-compacted, its thickness differs significantly from the net dimensions. To better meet the requirements of the RTM process for process part dimensions, hot-pressing pretreatment can be performed after layup using an iron or hot air blower. This allows excess adhesive from the extension portion to enter the ribs (fiber fabric, preferably dry carbon cloth) around the overlapping portion. This achieves dimensional compression, bringing it closer to the preset net dimensions, and also makes the connection between the extension portion and the ribs more stable, avoiding or reducing wrinkles and misalignments of the dry carbon cloth in the overlapping portion of the extension portion and the ribs. It is important to note that the temperature of the hot-pressing pretreatment must not exceed the thermosetting temperature of the prepreg adhesive.

[0112] Specifically, step S5 involves the following steps: First, close the mold. After mold closure, prepare the adhesive and connect it to the mold's injection port for injection. After injection, heat the mold to the selected material's (adhesive's) curing temperature. Then, cure the laid-up product. After curing, cool the mold and demold.

[0113] For example, the adhesive used for injection molding is one or more of room temperature epoxy resin, medium temperature epoxy resin, or high temperature epoxy resin. The adhesive has good miscibility, can achieve co-curing, and exhibits excellent structural strength after final molding.

[0114] For example, a more common set of operating parameters is as follows: after the glue injection is completed, close the glue injection port valve, put the mold for forming the part into the oven for curing, set the oven temperature to 120-130℃, cure for no less than 120 minutes, and then use a fan to cool it down to 30℃ before demolding.

[0115] Specifically, the prepreg uses a rubber compound that is miscible with the rubber compound used in RTM injection in step S5 and can be co-cured to prevent internal delamination during co-curing.

[0116] For example, possible adhesive combinations include random combinations of room temperature epoxy resin, medium temperature epoxy resin, or high temperature epoxy resin. Preferably, a medium temperature epoxy resin is preferred, as room temperature epoxy resins cure easily at room temperature, and high temperature epoxy resins have excessively high curing temperature requirements, both of which are unfavorable for the production of conventional components. However, when the production or application environment is special, either room temperature epoxy resin or high temperature epoxy resin can be selected. For example, for components operating in high-temperature environments, a combination of "high temperature epoxy resin + high temperature epoxy resin" is preferred.

[0117] Example 1

[0118] A cylindrical rotating component with a window, measuring 500mm in circumference, 600mm in height, and 8mm in thickness, is prepared. The window has an inner diameter of 80mm x 80mm, a width of 25mm, and a thickness of 8mm. Two annular ribs, each 8mm thick, are provided. Figure 2 As shown.

[0119] Prepare dry carbon cloth, medium-temperature epoxy resin plain weave carbon cloth prepreg, release cloth, and molds for pre-compacting molds and component molding. Because the ribs are thick and the component is a complex rotating part, soft film molding molds are used for the inner surface of the molds used for component molding.

[0120] Five layers of plain weave carbon fiber prepreg are laid out and cut into 32 sets of rectangles with a length * width * thickness of 250mm * 25mm * 1mm. The initial thickness of each layer of plain weave carbon fiber prepreg is 0.25-0.30mm, and the final pre-compacted / design net size is 0.2mm. Among them, "80 + 25 * 2 = 130mm" in the length direction is used to form the window frame, and the remaining part (about 60mm on each side, a total of 120mm) is used as the extension part extending outward along the window frame. It will be appropriately cut according to the parting design and specific layup method during the subsequent layup process.

[0121] Five layers of plain carbon fiber are laid out and cut into 16 rectangles with a length * width * thickness of 510mm * 25mm * 1mm. Each layer of plain carbon fiber is 0.2mm thick and will be used as ribs. Eight layers of plain carbon fiber with a length * width * thickness of 510mm * 610mm * 1mm and window-shaped cutouts are cut out and will be 0.2mm thick and will be used as skin.

[0122] To prepare the pre-compressed solid, refer to the prepared pre-compressed mold (female mold) as follows. Figure 3 The shape shown is constructed with 8 groups of prepreg layers on each side, totaling 32 groups, using a cross-cut layup method (e.g., ...). Figure 4 As shown in the diagram, the cross-cut layup includes cut-off layers and non-cut-off layers; the cut-off layer refers to cutting the weft prepreg and inserting the warp prepreg into the middle of the cut-off weft prepreg, with the end face of the cut-off weft prepreg connected to the two side edges of the warp prepreg; the non-cut-off layer refers to cutting the warp prepreg to a suitable size during layup, with the end face of the warp prepreg connected to the edge of the weft prepreg, and the weft prepreg not needing to be cut off; the cut-off layers and non-cut-off layers are arranged adjacently at intervals.

[0123] During each layer layup, excess material is trimmed off. After the layup is completed, the mold is heated to 85°C and pressed to close. After holding at this temperature for 30 minutes, the mold is cooled to 30°C using a fan before demolding to prepare a pre-compressed solid for later use. During the layup, to prevent the extension connected to the ribs from sticking together, after each layer layup, the extension connected to the ribs is wrapped with a release cloth 1-2 times and cooled with a fan during the pre-compressing process. The pre-compressed state is when the prepreg is in an uncured state.

[0124] Prepare the soft film molding die and remove the release cloth from the prepreg in the extension section. Then, use 16 sets of plain weave carbon fiber cloth (8 sets for each of the two ribs) measuring 510mm x 25mm x 1mm in length x width x thickness in the rib forming groove of the die to perform a stacked, cut-down layup with the prepreg in the extension section (e.g., Figure 5As shown in the figure, the stacked cut-off layup includes insert layers and non-insertion layers; the insert layer refers to cutting off the ribs, inserting the extension into the middle of the cut ribs, connecting the end face of the cut ribs to the two side edges of the extension, and cutting off the excess part of the extension; the non-insertion layer refers to cutting the extension to a suitable size, connecting the end face of the extension to the edge of the rib during layup, and the ribs do not need to be cut off; in this embodiment, the insert layers and non-insertion layers are arranged adjacently at intervals, that is, the number of insert layers accounts for 50%.

[0125] After the prepreg and ribs of the extension section are laid up, eight sets of window-shaped skins with a length*width*thickness of 510mm*610mm*1mm are laid up on the pre-compressed solid and ribs (rotary mold). After the layup is completed, the remaining mold is tightened with screws and the molding mold is injected with resin (medium-temperature epoxy resin). After the resin injection is completed, the injection port valve does not need to be closed. The mold is placed in an oven for curing. The oven temperature is set to 125℃. After curing for 120 minutes, the resin is extruded and cooled to 30℃ with a fan before demolding to obtain a rib-reinforced window composite material part with dry and wet co-curing characteristics using RTM process.

[0126] The thickness tolerance of the component is 7.2 to 8.8 mm, and the longitudinal and transverse tensile strengths of the component are both 320 ± 10 MPa.

[0127] Window composite components reinforced with an integral frame (window frame + extension + ribs) have better mechanical properties than window composite components without an integral frame (no extension or extension not connected to ribs, thus not forming an integral frame). The integration between the window and the component is better, and the component quality is significantly improved.

[0128] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A cylindrical component with a window rib structure, characterized in that, The component includes a window frame (5), an extension (4), ribs (2) and a skin (3), the extension (4) extending outward along the window frame (5), and the extension (4) and the window frame (5) having a continuous fiber structure; The skin (3) forms the cylindrical body of the component, and the ribs (2) and window frame (5) are disposed on the inner surface of the cylindrical component and connected by the extension (4); The component is integrally molded using RTM technology.

2. The cylindrical component according to claim 1, characterized in that, The window is a triangle, square, rectangle or other irregular polygon; the shape of the window frame (5) matches the shape of the window.

3. The cylindrical component according to claim 1, characterized in that, The number of the extension (4) is not less than 3; the rib (2) is an annular rib arranged along the circumferential direction and / or a strip rib arranged along the axial direction, and the number of the rib (2) is not less than 2.

4. The cylindrical component according to claim 1, characterized in that, The window frame (5) and extension (4) are made of prepreg; the ribs (2) and skin (3) are made of fiber fabric.

5. A method for preparing the cylindrical component according to any one of claims 1 to 4, characterized in that, Specifically, the following steps are included: S1: Based on the component structure, perform parting design and prepare skin (3), ribs (2), prepreg, pre-compacted mold and component molding mold in advance; S2: Prepreg is used to cross-lay out the window frame preform (1) according to the parting design in the female mold of the pre-compacting mold. The window frame (5) is located inside the pre-compacting mold and the extension (4) is located outside the pre-compacting mold. S3: After the layup is completed, the temperature is increased and the pressure is applied to close the mold and pre-compacted. The window frame (5) is pre-compacted, while the extension (4) is not pre-compacted. During the pre-compacting process, the extension (4) is cooled down. After cooling and demolding, the pre-compacted window frame preform (1) is obtained. S4: Lay up the skin (3), window frame preform (1), and ribs (2) in the negative mold of the component forming mold according to the parting design, and overlap the extension (4) of the window frame preform (1) with the ribs (2). S5: After mold closing, RTM injection, heating and curing, and demolding, an integrally formed structure with window ribs (2) can be obtained.

6. The preparation method according to claim 5, characterized in that, The process of parting design in step S1 is as follows: parting design is carried out according to the overall shape of the structural component containing window ribs (2), and the overall structure is divided into three parts: window frame preform (1), ribs (2) and skin (3). The window frame preform (1) includes a window frame (5) and an extension (4) extending outward along the window frame (5). The extension (4) is used to connect the window frame preform (1) with the ribs (2).

7. The preparation method according to claim 5, characterized in that, In step S2, during the cross-laying of the prepreg, the stacked portion is laid out using a cross-cutting method. The cross-cut ply includes cut-off layers and non-cut-off layers; The cut-off layer refers to cutting off the weft-direction prepreg and inserting the warp-direction prepreg into the middle of the cut-off weft-direction prepreg, with the end face of the cut-off weft-direction prepreg connected to the two side edges of the warp-direction prepreg. The non-cut-off layer refers to the prepreg in the warp direction being cut to a suitable size during laying, with the end face of the prepreg in the warp direction connected to the edge of the prepreg in the weft direction during laying, and the prepreg in the weft direction not needing to be cut off. The cut-off layers and non-cut-off layers are arranged at adjacent intervals.

8. The preparation method according to claim 5, characterized in that, In step S4, the overlapping portion of the rib (2) and the extension (4) is laid up using a stacked cut-off method; The stacked truncated layup includes inserted layers and non-inserted layers; The insertion layer refers to cutting off the rib (2), inserting the extension (4) into the middle of the cut-off rib (2), connecting the end face of the cut-off rib (2) with the two side edges of the extension (4), and cutting off the excess part of the extension (4). The non-insertion layer refers to cutting the extension (4) to a suitable size, and when laying it, the end face of the extension (4) is connected to the edge of the rib (2), and the rib (2) does not need to be cut off; The inserted layers account for 25% to 75% of the total number of layers in the stacked portion, and the total number of layers in the stacked portion = the number of inserted layers + the number of non-inserted layers.

9. The preparation method according to claim 5, characterized in that, When the rib (2) is an annular rib, during the layup process in step S4, the joint of the rib (2) is cut and a toothed structure with interlocking is used for layup to form a complete annular rib.

10. The method according to claim 5, characterized in that, After the layup is completed in step S4, the extension (4) and the overlapping part of the extension (4) and the rib (2) are subjected to hot pressing pretreatment so that the dimensions of the extension (4) and the overlapping part reach the preset net dimensions.

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