Fin stabilizer top rib and method of forming

Abstract

The application relates to the assembly technology field of an aircraft composite material structure, and discloses a forming method of a vertical tail stabilizer top rib plate, which comprises the following steps: thawing raw materials: thawing the frozen pre-impregnated material to a thawing completion state, and cutting the pre-impregnated material into pieces according to layering requirements; laying and pasting: laying and pasting the pieces on a mold in a layering table sequence and assisting with vacuum compaction, checking the fiber direction and removing air bubbles after laying and pasting each layer; wherein the fabric pre-impregnated material and unidirectional fiber silk are used to fill and transition the area prone to hollowing / bridging, the joint positions are staggered in the layer, and the joint positions of adjacent layers do not coincide; packaging: packaging a vacuum bag with the vacuum curing auxiliary material on the laid and pasted body, and detecting the vacuum pressure maintaining performance to ensure good sealing; curing and demolding: curing the packaged product according to the set curing parameters, removing the auxiliary material after cooling, and demolding to obtain the rib plate part. The application realizes low-cost composite material part manufacturing, composite material net edge manufacturing, and stable satisfaction of design requirements.

Description

Technical Field

[0001] This application relates to the field of composite material assembly technology, and in particular to a top rib plate of a vertical tail stabilizer and its forming method. Background Technology

[0002] The top rib of the vertical stabilizer is an important component of the aircraft's vertical tail structure. As a reinforcing structure within the stabilizer, it transmits aerodynamic loads, maintains aerodynamic shape, and supports the skin, directly impacting the overall structural stiffness, strength, and aerodynamic performance of the aircraft's vertical tail. With the aerospace industry's increasing pursuit of lightweight and high performance, carbon fiber composite materials, due to their outstanding advantages such as high specific strength, high specific stiffness, good fatigue resistance, and strong design flexibility, are increasingly being used in the manufacture of various aircraft structural components.

[0003] However, in existing technologies, the following technical problems typically exist when using composite materials to manufacture irregularly shaped structural components such as the top rib of the vertical stabilizer: First, the manufacturing cost is relatively high. The traditional manufacturing process of composite ribs is complicated, often requiring separate workstations for cutting, laying, and curing, as well as a large investment of tooling, equipment, and manpower. Moreover, due to the lack of integrated process control, rework and scrap often lead to waste of materials and time. At the same time, poor storage, thawing, and life management of prepregs can directly cause a large amount of raw materials to be scrapped, further increasing manufacturing costs.

[0004] Secondly, it is difficult to achieve clean edge manufacturing. In existing processes, after the product is laid, there are often rough edges and burrs around the perimeter, which need to be trimmed separately after curing. This not only increases the number of steps and time, but also easily damages the product surface, causes fiber fuzzing or delamination during the trimming process, and affects the mechanical properties and surface quality of the product. It is difficult to obtain a clean, flat product with clean edges without excess material.

[0005] Third, it is difficult to consistently meet design requirements. The ribbed structure is complex, including corners, steps, and core material splicing areas. During the installation process, hollow areas and bridging are prone to occur at corners and steps, overlapping or misalignment at joints, and gaps at core material splicing. These defects can lead to quality problems such as internal inclusions, resin deficiency, resin excess, dry spots, fiber wrinkles or twisting, directly affecting the product's appearance and mechanical properties, making it difficult to consistently meet design requirements. Summary of the Invention

[0006] The purpose of this application is to provide a method for forming the top rib of the vertical tail stabilizer, so as to achieve low-cost composite part manufacturing, composite edge cleaning manufacturing, and stable fulfillment of design requirements.

[0007] To solve the above-mentioned technical problems, this application provides a method for forming a top rib of a tail stabilizer, comprising the following steps: S1: Thawing and material preparation: Thawing the frozen prepreg until it is fully thawed, and then cutting it into sheets according to the layup requirements; S2: Laying: Laying the sheets layer by layer onto the mold according to the layup table and vacuum compacting them. After each layer is laid, the fiber direction is checked and air bubbles are removed; in areas prone to air bubbles / bridging, woven prepreg and unidirectional fiber filaments are used to fill and transition the gaps, and the seams are staggered within the layers and the seams of adjacent layers do not overlap; S3: Encapsulation: Vacuum bags are assembled on the laid body using vacuum curing auxiliary materials and the vacuum pressure performance is tested to ensure good sealing; S4: Curing and demolding: The encapsulated product is cured according to the set curing parameters, and after cooling, the auxiliary materials are removed and the product is demolded to obtain the rib part.

[0008] Optionally, in the thawing and preparation step: the frozen prepreg is thawed for no less than 8 hours. Thawing is considered complete when the surface of the outer packaging no longer condenses water droplets / vapor after wiping it dry. During the thawing process, the outer packaging is kept sealed.

[0009] Optionally, in the thawing and material preparation step: before thawing the frozen prepreg, check its storage expiration date, remaining operational life, and mechanical property life to ensure that the remaining operational life is >0h and the remaining mechanical property life is >0h; the thawed prepreg is cut according to the layup requirements, and the allowable deviation of the sheet size is ±2.5mm; if the laying process is not planned to start within 48 hours, the cut sheets are bagged and sealed back into the frozen environment, and thawed again before the laying begins.

[0010] Optionally, in the laying step: the areas prone to hollowing / bridging are corners and step areas, which are filled by laying a layer of 15mm wide prepreg fabric of the same type as the product, and then filling with carbon fiber unidirectional fibers according to the R-angle size of the part and making a smooth transition.

[0011] Optionally, in the laying step: the prepreg seams are overlapped in non-fitting areas with an overlap width of 25-35mm; butt joints are used in fitting areas with a butt joint gap of ≤1mm; when several layers overlap / butt joint in adjacent layers, the seam positions are staggered by at least 25mm, and seams at the same position are at least 4 layers apart in the thickness direction.

[0012] Optionally, in the laying steps: after filling areas prone to hollowing / bridging, expandable foam is used to fill the seams of the core material when laying large areas of core material; after each layer of prepreg is laid, a scraper and / or a blower are used to assist in heating along the fiber direction to remove air bubbles and smooth out wrinkles, and a knife is used to remove excess prepreg outside the laying area; the backing release paper and release film are retained during the laying process, and after laying is completed, the backing is counted and checked to ensure that there are no impurities or foreign objects.

[0013] Optionally, in the laying steps: vacuum pre-compaction is performed during the laying process, with a vacuum degree requirement of -100KPa to -80KPa, and the holding time is not less than 15 minutes; after the last layer is laid, vacuum bags are made using vacuum compaction auxiliary materials, with pleats evenly and symmetrically set in the vacuum bags, and the compaction vacuum degree requirement of -100KPa to -85KPa, and the holding time is not less than 1 hour.

[0014] Optionally, in the encapsulation step: after evacuating to a pressure value of -100KPa to -85KPa at the detection point, stop, and check that the vacuum degree decay value of all detection points within 15 minutes is not greater than 5KPa; if the decay value exceeds the standard, check for and fill any leaks in the vacuum bag film, vacuum pipeline, vacuum quick-connect suction cup and mold, and then repeat the vacuum degree test.

[0015] Optionally, in the curing step: before curing, ensure that the remaining operating life of the prepreg is >0h and the remaining mechanical property life is >0h; set the curing parameters to 2h@85℃+2h@120℃, and remove the product from the oven after the temperature drops below 60℃, and then demold after it cools naturally to room temperature.

[0016] Optionally, in the curing step: the prepreg is a carbon fiber fabric prepreg with a single-layer thickness of 0.22 mm and a reference layup structure of [±45 / (0 / 90)]n / PMI / [±45 / (0 / 90)]. n Laying out the tiles.

[0017] Optionally, during the demolding process: After demolding, visually inspect the parts for defects such as resin deficiency, resin richness, fiber wrinkles / creases / cracks / scratches, dry spots or surface pores, fiber deformation and twisting. If there are defects, mark and record them on the product surface, then weigh and record (retain 3 significant figures after the decimal point, weight unit KG), and after reporting to quality inspection, transfer qualified parts to assembly.

[0018] This application also provides a top rib of a vertical tail stabilizer, the rib being prepared from carbon fiber fabric prepreg using the molding method described above.

[0019] Optionally, the rib is an integrally formed clean-edge structure, with its outer edge being a sandwich structure formed by sequentially laying down carbon fiber prepreg fabric [±45 / (0 / 90)]n / PMI / [±45 / (0 / 90)]. n A symmetrical layered structure.

[0020] Optionally, the corners and steps of the rib plate are clean-edge transition structures, formed by filling the prepreg fabric layer and carbon fiber unidirectional fibers with a smooth transition, and the surface is free of voids, bridging and wrinkles.

[0021] Optionally, the joints of adjacent layers at the rib joints are staggered by at least 4 layers in the thickness direction, the spacing of the joints within the layers is staggered by at least 25 mm, and the surface is free of foreign matter inclusions, dry spots, and areas with low or high resin content.

[0022] Compared with the prior art, this application has the following beneficial effects: First, it achieves low-cost manufacturing. This application systematically integrates processes such as thawing, material preparation, application, encapsulation, curing, demolding, and inspection, and effectively manages the storage, thawing, and lifespan of the prepreg, avoiding raw material scrap and rework waste, and significantly reducing manufacturing time and material costs; at the same time, by scheduling rapid turnover and first application within 48 hours, repeated thawing is reduced, further saving energy and time.

[0023] Second, it achieves clean edge manufacturing of composite materials. This application achieves a clean and flat edge structure after curing and demolding without additional trimming by precisely cutting the material sheets (dimensional deviation ±2.5mm), promptly removing excess prepreg outside the laying area during the laying process, and strictly controlling the joint / overlap area. This avoids fiber damage and surface quality degradation caused by trimming.

[0024] Third, it stably meets design requirements. This application uses prepreg fabric filling layers and unidirectional fiber filaments to fill corners and stepped areas prone to hollowing / bridging, with smooth transitions. It controls the seams by staggering them by at least 25mm within the layers and by spacing them at least 4 layers apart in the thickness direction. It also fills the core material seams with foam adhesive and conducts multiple vacuum compaction and vacuum pressure holding performance tests. This effectively eliminates defects such as hollowing, bridging, wrinkles, inclusions, dry spots, resin deficiency, and resin richness, ensuring the product's density and mechanical properties and stably meeting design requirements. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating the process of forming the top rib of the vertical tail stabilizer in one embodiment of this application. Figure 2 This is a flowchart illustrating the process of forming the top rib of the vertical tail stabilizer in one embodiment of this application. Figure 3 This is a schematic diagram of the sandwich structure of the top rib of the vertical tail stabilizer according to an embodiment of this application. Detailed Implementation

[0026] The following embodiments further illustrate the technical solutions of this application. It should be understood that the specific embodiments described herein are merely for explaining this application. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not all of them.

[0027] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0028] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0029] The present application will be further described in detail below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present application. All technical solutions implemented based on the above content of the present application fall within the scope of protection claimed in this application.

[0030] This embodiment provides a molding method for the top rib of a vertical stabilizer, mainly applicable to the preparation of the top rib of a vertical stabilizer using carbon fiber fabric prepreg. The method generally includes the main processes of thawing and material preparation, laying, encapsulation, curing, and demolding. Specifically, the process flow is as follows: First, proceed with step S1: Thawing and material preparation: Thaw the frozen prepreg until it is fully thawed, and then cut it into sheets according to the layering requirements.

[0031] Specifically, the required carbon fiber fabric prepreg material is taken out from a frozen environment (usually a freezer at around -18°C), and the storage expiration date, remaining operational life, and mechanical property life of the material are checked to ensure that the remaining operational life and remaining mechanical property life of the material are greater than 0 hours, thereby ensuring that the material is within the allowable range of reliable performance during the subsequent laying and curing process.

[0032] The materials should then be thawed for at least 8 hours. During thawing, the outer packaging must remain intact and unopened or damaged. Thawing is complete when no more water droplets or moisture condense on the surface of the outer packaging after wiping it dry. Thawing must be carried out in a controlled temperature and humidity environment in the installation room to ensure the stability of the materials. If damage to the outer packaging is found during handling, it should be immediately sealed with tape, and the start and end times of thawing should be recorded.

[0033] After thawing, the fabric is prepared and cut into sheets using an automatic fabric cutting machine according to the layering requirements. The allowable deviation in sheet size is ±2.5mm. The sheet packaging is marked with the part name, drawing number, and other information before being transferred to the laying station. If the laying process is not planned to start within 48 hours, the cut sheets are bagged and sealed back into the freezer. They are then thawed again before the laying process begins to prevent the sheets from becoming damp or aging due to prolonged exposure.

[0034] Next, proceed to step S2: Laying: Lay the material sheets layer by layer on the mold according to the layup table and then vacuum compact them. Check the fiber direction and remove air bubbles after each layer is laid. In areas prone to air bubbles / bridging, use prepreg fabric and unidirectional fiber filaments to fill and transition. The seams are staggered within the layers and the seams of adjacent layers do not overlap.

[0035] Specifically, the thawed and prepared prepreg sheets are laid layer by layer onto the treated mold according to the layer sequence and number of layers required by the layup schedule, and then vacuum-compacted. After each layer of prepreg is laid, the fiber direction of that layer is visually inspected to ensure it matches the angle specified in the layup schedule. A scraper and blower are used with the aid of heating to remove air bubbles and smooth out wrinkles generated during the laying process along the fiber direction. Simultaneously, scissors and utility knives are used to remove prepreg outside the laying area to ensure a smooth and accurate layup. During the laying process, for corners and steps prone to hollowing / bridging, a 15mm wide layer of fabric prepreg, identical to the product, is laid to fill the gaps. Then, carbon fiber unidirectional yarns are used to fill the gaps according to the radius (R) of the part, creating a smooth transition, thereby fundamentally eliminating hollowing and bridging defects at corners and steps.

[0036] For seams, butt joints or overlaps should be performed according to the process specifications: overlaps should be used in non-fitting areas, with an overlap width of 25-35mm; butt joints should be used in fitting areas, with a butt joint gap of ≤1mm. If several adjacent layers overlap / butt joints occur, the seam positions should be staggered by at least 25mm, and seams at the same position should be separated by at least 4 layers in the thickness direction to avoid overlapping seams and creating weak areas.

[0037] When laying the core material, use expanding foam to fill the seams between the core materials to ensure a seamless connection. Throughout the laying process, retain the backing release paper and release film, and count and check them at the end to ensure that no impurities or foreign objects are formed.

[0038] Vacuum pre-compaction is performed during the laying process, with a vacuum degree requirement of -100KPa to -80KPa, and the time is not less than 15 minutes. After the last layer is laid, vacuum bags are made using vacuum compaction auxiliary materials. The vacuum bags are evenly and symmetrically pleated, and the compaction vacuum degree requirement is -100KPa to -85KPa, which is maintained for not less than 1 hour to fully compact each layer and remove air between layers.

[0039] Next, proceed to step S3: Encapsulation: Assemble a vacuum bag on the substrate using vacuum curing auxiliary material, and test the vacuum pressure holding performance to ensure a good seal.

[0040] Specifically, place component labels, thermocouples, and vacuum extraction points on the product as required. Use vacuum curing auxiliary materials to assemble vacuum bags and seal the substrate. Turn on the vacuum pump to remove air from the vacuum bag membrane. Stop vacuuming when the pressure at all testing points reaches -100 kPa to -85 kPa. Check that the vacuum decay at all testing points does not exceed 5 kPa within 15 minutes. If the decay exceeds 5 kPa, check for leaks in the vacuum bag membrane, vacuum tubing, vacuum quick-connect suction cups, mold, etc. If leaks are found, fill them with yellow sealing strips and repeat the vacuum test until the vacuum pressure performance is satisfactory and the seal is good.

[0041] Then proceed to step S4: curing and demolding: the packaged product is cured according to the set curing parameters, and after cooling, the auxiliary materials are removed and the product is demolded to obtain the rib plate part.

[0042] Specifically, before curing, ensure the remaining operating life and remaining mechanical property life of the prepreg are both greater than 0 hours. Place the molded product, along with the finished encapsulation, into the oven, connecting vacuum lines and thermocouples for data acquisition and control. Perform a vacuum test again. Stop vacuuming when the pressure at the test point reaches -100 kPa to -85 kPa. Check that the vacuum decay within 15 minutes does not exceed 5 kPa. If it fails to meet the standard, investigate and fill any leaks, then repeat the test. Set the curing parameters to 2 hours at 85°C + 2 hours at 120°C to cure the product. Remove the product from the oven when the temperature drops below 60°C.

[0043] Finally, demold. After the product temperature has naturally dropped to room temperature, remove the vacuum bag film, breathable felt, non-porous isolation film, release cloth, sealing strips, and other auxiliary materials from the surface of the parts. Remove the thermocouples and vacuum connectors and clean them, placing them in their designated positions. Use a nylon release wedge to gradually insert along the gap between the edge of the part and the mold, gently prying to separate the part from the mold, and clean any residual adhesive from the mold surface.

[0044] After demolding, proceed to step S5: Inspection: Perform an appearance quality inspection on the parts, visually check for defects, circle and record any defects on the product surface with a white paint pen, and finally hand over qualified parts to the assembly.

[0045] Specifically, after demolding, the parts undergo a visual quality inspection. This involves checking for areas lacking resin, fiber wrinkles / creases / cracks / scratches, the integrity of the release cloth, the presence of dry spots or surface pores, areas rich in resin, and areas of fiber deformation or twisting. Any defects are circled and recorded on the product surface with a white paint pen. The product is then weighed, retaining three decimal places (in kg), and reported to the quality department for further quality inspection. Finally, qualified parts are handed over for assembly.

[0046] The method described in this embodiment achieves low-cost manufacturing, clean edge manufacturing of composite materials, and stable compliance with design requirements through systematic integration and parameter control of each process.

[0047] In one embodiment, the thawing and preparation steps of Example 1 are further refined. Before thawing and preparation, the operator first removes the material from the frozen environment and checks the material's storage expiration date, remaining operational life, and mechanical property life. It is ensured that the remaining operational life is greater than 0 hours, and simultaneously, the remaining mechanical property life is greater than 0 hours. Both conditions must be met simultaneously; failure to meet either condition renders the material unqualified and unsuitable for batch production. The thawing time is no less than 8 hours, and thawing is carried out in the laying room. Thawing is considered complete when the outer packaging is wiped dry and no more water droplets / vapor condense. During thawing, the outer packaging must not be opened or damaged. If the packaging bag is found to be damaged during handling, it must be immediately sealed with tape. The start and end times of thawing must be recorded for traceability and auditing. When using an automatic fabric cutting machine to prepare and cut prepreg, the roll length edge must coincide with the machine's 0° line. The fiber direction angle deviation is generally ±2° for unidirectional prepreg and ±3° for woven prepreg. The allowable deviation for sheet size is ±2.5mm. By strictly controlling fiber angle deviation, the fiber direction of each cut sheet is ensured to be accurate, thereby guaranteeing that the overall layup angle meets design requirements. After cutting, the quantity and markings of the sheets are checked, and the part name, drawing number, and other information are marked on the sheet packaging before being transferred to the laying station. If laying is not planned to begin within 48 hours, the cut sheets are individually bagged and sealed back into the freezer. They are then thawed before the laying process begins, thus preventing the sheets from absorbing moisture and aging due to prolonged exposure to room temperature, ensuring stable material performance.

[0048] In one embodiment, to further improve the molding quality of the ribs, the mold is thoroughly prepared before installation. Specifically, first, confirm that the mold is in normal condition and record the mold number. Confirm that the mold markings and scribe lines are complete and clear so that the material pieces can be accurately positioned according to the scribe lines during installation. Clean the mold and tooling surfaces of dust and adhesive residue using a white cotton cloth, cleaning agent, plastic scraper, and vacuum cleaner to ensure the mold surface is clean. Use masking tape to isolate and protect the area where the bag-making sealing strip is applied. When applying the release agent, wear a mask, gloves, and protective glasses. Do not apply the release agent in the installation room to avoid volatile substances contaminating the installation environment and prepreg. For molds used for the first time or cleaned with cleaning agent, apply 5 coats of release agent. After each subsequent part is demolded, apply 3 coats of release agent, with at least 15 minutes between each coat. The next process can only be carried out at least 30 minutes after the last coat of release agent is applied. For areas where it is inconvenient to apply release agent, apply fluorinated release cloth with adhesive backing to ensure the demolding effect. If the molds after the release agent application are placed outside the tiling area, a thin film must be used to cover the mold surface to prevent dust and foreign matter contamination. Thorough mold preparation ensures smooth demolding and a clean product surface, which is an important prerequisite for achieving clean edge manufacturing.

[0049] In one embodiment, the preparation of auxiliary materials is described. According to the requirements of the lamination process, a set of auxiliary materials for vacuum pre-compression is cut, including a porous release film, a release cloth, a breathable felt, and a vacuum bag film; simultaneously, a set of auxiliary materials for vacuum curing is cut, including a release cloth, a non-porous release film, a breathable felt, and a vacuum bag film. Both sets of auxiliary materials are cut according to the actual area of ​​the part to be laminated. The vacuum bag film is cut to size according to the mold size, ensuring that the vacuum bag film completely covers the product and mold edges, and leaving allowance for pleating. This allows for uniform and symmetrical shrinkage during vacuuming, preventing tearing due to excessive tightness or wrinkling due to excessive looseness, which would affect the vacuum seal. Precise cutting of the auxiliary materials avoids waste, saves costs, and ensures the sealing effect and compaction quality of vacuum sealing and curing.

[0050] In one embodiment, a comprehensive inspection and confirmation of the laying environment, equipment, and material condition is conducted before the laying operation begins. First, the ambient temperature and humidity of the laying room are checked, confirming that the temperature is within the range of 22±4℃ and the humidity is ≤60%. Temperature and humidity data are recorded to ensure that the prepreg laying operation is carried out under suitable environmental conditions, avoiding premature resin cross-linking due to excessive temperature or moisture absorption by the material due to excessive humidity. Second, the measuring instruments are checked to ensure they meet usability requirements and are within their calibration validity period, ensuring the accuracy and reliability of subsequent weighing, testing, and other data. Third, the remaining operating life and mechanical property life of the raw materials are checked to ensure they meet requirements, ensuring that the remaining operating life is >0 hours and the remaining mechanical property life is >0 hours. Finally, the mold information is checked to ensure it is correct and that bolts, latches, and other accessories are complete, ensuring that the tooling and equipment are complete and in place during the laying process. This pre-laying inspection provides a prerequisite guarantee for the operation, enabling the laying process to be carried out stably, continuously, and with high quality.

[0051] In one embodiment, the installation process is specifically described for corners, steps, and large flat surfaces of the rib structure. For areas prone to hollowness / bridging, such as corners and steps, a 15mm wide layer of prepreg fabric identical to the product is applied for filling. Then, carbon fiber unidirectional filaments are used for further filling and smooth transition according to the radius (R) of the part, thereby eliminating hollowness and bridging. For seams, butt joints / overlaps are performed according to process specifications: generally, the prepreg fabric should overlap in non-fitting areas with an overlap width of 25-35mm; in fitting areas, it should be butt jointed with a butt joint gap ≤1mm. If several related layers overlap / butt joint, the seam positions should be staggered by at least 25mm, and seams at the same location should be at least 4 layers apart in the thickness direction to avoid concentrated weak areas. After each layer of prepreg is laid, visually inspect it to ensure the fiber direction aligns with the angle within the layup surface. Use a scraper and a blower to assist heating and remove air bubbles and wrinkles generated during the laying process along the fiber direction. Use scissors and a utility knife to remove prepreg outside the laying area, ensuring a smooth, bubble-free, and burr-free layup. When laying large areas of core material, fill the seams with expanding foam to prevent gaps. Throughout the laying process, retain the backing release paper and release film, and count and check after completion to ensure no inclusions or foreign matter are formed. Perform vacuum pre-compaction according to the required layer sequence on the layup surface. Use vacuum pre-compaction auxiliary materials to assemble vacuum bags. The vacuum degree required for vacuum pre-compaction is -100KPa to -80KPa, and the holding time should not be less than 15 minutes. After the final layer is laid, vacuum bags are assembled using vacuum compaction auxiliary materials according to the sealing process. The vacuum bags should have evenly and symmetrically arranged pleats, and the compaction vacuum degree should be -100KPa to -85KPa, maintained for no less than 1 hour. The laying process in this embodiment is the core process to ensure that the product is free from defects such as voids, bridging, wrinkles, and inclusions, achieving clean edge manufacturing and meeting design requirements.

[0052] In one embodiment, the packaging process is described. Component labels, thermocouples, and vacuum extraction points are placed as required. A vacuum bag is assembled using vacuum curing auxiliary materials to seal the substrate. During vacuum testing, the vacuum pump is turned on to remove air from the vacuum bag film. Vacuuming is stopped when the pressure values ​​at all testing points reach -100 kPa to -85 kPa. The vacuum decay value at all testing points must not exceed 5 kPa within 15 minutes. If the decay value exceeds 5 kPa, leaks must be checked in the vacuum bag film, vacuum tubing, vacuum quick-connect suction cups, mold, etc. If leaks are found, yellow sealing strips can be used to fill the leaks. The vacuum testing operation is repeated until the vacuum decay value meets the requirements and the seal is confirmed to be good before proceeding to the curing process. Strict vacuum pressure testing ensures that the substrate remains under stable pressure during the curing stage, which helps to fully expel gas, improve product density and dimensional stability, and is a quality assurance method to achieve design requirements.

[0053] In one embodiment, the curing and demolding processes are described. For prepreg materials, before the laying process is completed, it must be ensured that the remaining operational life of the material is >0 hours; before turning on the heating equipment for curing, it must be ensured that the remaining mechanical life of the material is >0 hours. The vacuum-sealed mold, along with the product, is sent into the oven, and the vacuum pipeline and thermocouple are connected to facilitate subsequent data collection and control of the curing process. Before curing, the vacuum degree is tested again. When the pressure value at the vacuum degree testing point reaches -100 kPa to -85 kPa, the vacuuming is stopped. The vacuum degree decay value at the vacuum testing point within 15 minutes is not greater than 5 kPa. If the decay value is greater than 5 kPa, the leak point must be checked and filled with sealing strips before retesting. The curing parameters are set as 2h@85℃+2h@120℃ for stepped curing, that is, first hold at 85℃ for 2 hours, then raise the temperature to 120℃ and hold for 2 hours. The product is removed from the oven when the temperature drops below 60℃, and then allowed to cool naturally to room temperature. Remove auxiliary materials such as vacuum bag film, breathable felt, non-porous isolation film, release cloth, and sealing strips from the surface of the part. Remove the thermocouple and vacuum connector and clean them thoroughly, placing them in their designated positions. Use a nylon release wedge to gradually insert along the gap between the part's edge and the mold, gently prying to separate the part from the mold. Clean any residual adhesive from the mold surface. This embodiment completes the crucial transformation from the preform to the finished product, ensuring both sufficient resin curing and cross-linking for good mechanical properties, and smooth demolding with an intact product surface.

[0054] This embodiment describes the quality inspection and handover of the product. After demolding, the parts undergo a visual quality inspection: First, visually inspect the parts for areas lacking resin; second, visually inspect the parts for defects such as fiber wrinkles, creases, cracks, or scratches that damage fibers, and circle these defects on the product surface with a white paint pen; third, visually inspect the integrity of the release cloth, and record any damage; fourth, visually inspect for dry spots or surface pores, and circle these defects on the product surface with a white paint pen; fifth, check for areas rich in resin, and circle these defects on the product surface with a white paint pen; sixth, check for areas of fiber deformation or twisting, and circle these defects on the product surface with a white paint pen. The product is then weighed and the weight recorded, retaining three decimal places, in kg. After weighing, the weight is reported to the quality department for quality inspection. Once the quality inspection is passed, the qualified parts are handed over to assembly. Through systematic visual quality inspection, weighing, and quality inspection, it is ensured that every product off the production line meets design requirements, achieving stable quality control.

[0055] In one embodiment, this application also provides a top rib plate for the tail stabilizer. This rib plate is prepared from carbon fiber prepreg using the molding method described in any of the above embodiments, and is an integrally molded clean-edge structure. Its outer edge has a sandwich structure, including a middle sandwich 100, an upper panel 200, and a lower panel 300, formed by sequentially laying down carbon fiber prepreg [±45 / (0 / 90)]n / PMI / [±45 / (0 / 90)]. n The symmetrical plywood structure features a PMI layer as the foam core, located in the middle 100mm of the interlayer. The upper panel 200mm and lower panel 300mm are both prepreg plywood layers made of carbon fiber fabric. The fiber angles alternate between ±45° and 0° / 90°, forming a symmetrical and balanced plywood system. This balances the stiffness and strength of the ribs while reducing structural weight. The corners and steps of the ribs have clean-edge transition structures, formed by prepreg filling layers and unidirectional carbon fiber filaments, resulting in a smooth and continuous surface free of voids, bridging, and wrinkles, thus avoiding stress concentration. All rib seams are staggered at least four times in the thickness direction, with a minimum 25mm spacing between seams within each layer. This ensures uniform seam distribution, prevents the formation of through-weak areas, and eliminates foreign matter inclusions, dry spots, and areas with either resin deficiency or excess. The overall appearance is clean, with regular fiber orientation, meeting the stringent design requirements of aerospace structural components. Furthermore, the elimination of the need for additional trimming significantly reduces manufacturing costs.

[0056] The above embodiments are merely illustrative of the principles and effects of this application. Any person skilled in the art can modify or alter the above embodiments without departing from the purpose of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the purpose disclosed in this application should still be covered by the claims of this application.

Claims

1. A method for forming the top rib of a vertical tail stabilizer, characterized in that, Includes the following steps: S1: Thawing and Preparing Materials: Thaw the frozen prepreg until it is fully thawed, and then cut it into sheets according to the layup requirements; S2: Laying: Lay the sheets onto the mold layer by layer according to the layup table and vacuum compact them. Check the fiber direction and remove air bubbles after each layer is laid. In areas prone to delamination / bridging, prepreg fabric and unidirectional fiber filaments are used for filling and transition, and the seams are staggered within the layers and the seams of adjacent layers do not overlap; S3: Encapsulation: Vacuum bags are assembled on the substrate using vacuum curing auxiliary materials and the vacuum pressure holding performance is tested to ensure good sealing; S4: Curing and Demolding: The packaged product is cured according to the set curing parameters. After cooling, the auxiliary materials are removed and the product is demolded to obtain the rib plate part.

2. The method for forming the top rib of the tail stabilizer according to claim 1, characterized in that, In the thawing and preparation step: the frozen prepreg is thawed for no less than 8 hours. Thawing is considered complete when the surface of the outer packaging no longer condenses water droplets / vapor after wiping it dry. During the thawing process, the outer packaging is kept sealed.

3. The method for forming the top rib of the tail stabilizer according to claim 1, characterized in that, In the thawing and material preparation step: Before thawing the frozen prepreg, check its storage expiration date, remaining operational life, and mechanical property life to ensure that the remaining operational life is >0h and the remaining mechanical property life is >0h; the thawed prepreg is cut according to the layup requirements, and the allowable deviation of the material sheet size is ±2.5mm; if the laying process is not planned to start within 48 hours, the cut material sheets are bagged and sealed and returned to the frozen environment, and thawed again before the laying begins.

4. The method for forming the top rib of the tail stabilizer according to claim 1, characterized in that, In the installation process: the areas prone to hollowing / bridging are corners and steps. A 15mm wide prepreg of the same fabric as the product is used to fill these areas. Then, carbon fiber unidirectional fibers are used to fill the area according to the radius of the part's radius and to create a smooth transition.

5. The method for forming the top rib of the tail stabilizer according to claim 1, characterized in that, In the laying steps: the prepreg seams are overlapped in non-fitting areas with an overlap width of 25-35mm; butt joints are used in fitting areas with a butt joint gap of ≤1mm; when several layers overlap / butt joint in adjacent layers, the seam positions are staggered by at least 25mm, and seams at the same position are at least 4 layers apart in the thickness direction.

6. The method for forming the top rib of the tail stabilizer according to claim 1, characterized in that, In the laying process: After filling areas prone to hollowing / bridging, expandable foam is used to fill the seams of the core material when laying large areas of core material; after each layer of prepreg is laid, a scraper and / or a blower are used to assist in heating along the fiber direction to remove air bubbles and smooth out wrinkles, and a knife is used to remove excess prepreg outside the laying area; the backing release paper and release film are retained during the laying process, and the number and check are made after laying to ensure that there are no impurities or foreign objects.

7. The method for forming the top rib of the tail stabilizer according to claim 1, characterized in that, In the laying process: Vacuum pre-compaction is carried out during the laying process, with a vacuum degree requirement of -100KPa to -80KPa, and the holding time is not less than 15 minutes; after the last layer is laid, vacuum bags are made using vacuum compaction auxiliary materials, with pleats evenly and symmetrically set in the vacuum bags, and the compaction vacuum degree requirement of -100KPa to -85KPa, and the holding time is not less than 1 hour.

8. The method for forming the top rib of the tail stabilizer according to claim 1, characterized in that, In the encapsulation step: Vacuum is drawn until the pressure value at the detection point reaches -100KPa to -85KPa and then stopped. The vacuum degree decay value at all detection points within 15 minutes is not greater than 5KPa. If the decay value exceeds the standard, the leaks in the vacuum bag film, vacuum pipeline, vacuum quick-connect suction cup and mold are checked and filled, and the vacuum degree test is repeated.

9. The method for forming the top rib of the tail stabilizer according to claim 1, characterized in that, In the curing step: Before curing, ensure that the remaining operating life of the prepreg is >0h and the remaining mechanical property life is >0h; set the curing parameters to 2h@85℃+2h@120℃, and remove the product from the oven after the temperature drops below 60℃, and then demold it after it cools naturally to room temperature.

10. The method for forming the top rib of the vertical tail stabilizer according to claim 1, characterized in that, In the curing step: the prepreg is a carbon fiber fabric prepreg with a single-layer thickness of 0.22 mm and a reference layup structure of [±45 / (0 / 90)]n / PMI / [±45 / (0 / 90)]. n Laying out.

11. The method for forming the top rib of the tail stabilizer according to claim 1, characterized in that, During demolding: After demolding, visually inspect the parts for defects such as resin deficiency, resin richness, fiber wrinkles / creases / cracks / scratches, dry spots or surface pores, fiber deformation and twisting. If there are defects, mark and record them on the product surface, then weigh and record (retain 3 decimal places, weight unit KG), and report to quality inspection before transferring qualified parts to assembly.

12. A top rib plate of a vertical tail stabilizer, characterized in that, The rib is prepared from carbon fiber fabric prepreg by the molding method described in any one of claims 1 to 11.

13. The top rib of the vertical tail stabilizer according to claim 12, characterized in that, The rib is a one-piece molded clean-edge structure, with its outer edge being a sandwich structure formed by sequentially laying layers of carbon fiber prepreg [±45 / (0 / 90)]n / PMI / [±45 / (0 / 90)]. n A symmetrical layered structure.

14. The top rib of the vertical tail stabilizer according to claim 12, characterized in that, The corners and steps of the ribs are clean-edge transition structures, formed by a prepreg filling layer of fabric and carbon fiber unidirectional fibers that are filled and smoothly transitioned, with no hollow areas, bridging, or wrinkles on the surface.

15. The top rib of the vertical tail stabilizer according to claim 12, characterized in that, The joints of adjacent layers at the rib plate joints are staggered by at least 4 layers in the thickness direction, and the spacing of the joints within the layers is staggered by at least 25 mm. The surface is free of foreign matter inclusions, dry spots, and areas with poor or rich resin.

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