A method of forming a flap and a composite flap produced thereby

Abstract

The application relates to the technical field of composite material forming, and discloses a mouth cover forming method, which comprises the following steps: S1, main material preparation; S2, mold preparation; S3, laying and pasting; S4, packaging; S5, solidification; S6, demolding; S7, cutting and edging; and S8, quality inspection.

Description

Technical Field

[0001] This application relates to the field of composite material molding technology, and in particular to a cap molding method and the composite material cap prepared therefrom. Background Technology

[0002] Currently, composite material caps are typically manufactured using compression molding or autoclave molding processes. These methods require expensive equipment and consume a lot of energy, resulting in high manufacturing costs. Therefore, this invention provides a cap molding method based on a non-autoclave process and the composite material cap produced therefrom, aiming to reduce manufacturing costs while meeting design requirements. Summary of the Invention

[0003] The purpose of this application is to provide a method for forming a cap, including the following steps: S1: Main material preparation: Remove the prepreg from the frozen environment and check the remaining operating life and remaining mechanical property life of the material to ensure that the remaining operating life is >0h and the remaining mechanical property life is >0h; Thaw the material for no less than 8 hours. Thawing is considered complete when no more water droplets / moisture condense after wiping the outer packaging dry; Cut the prepreg using an automatic fabric cutter, controlling the fiber direction angle deviation within ±2°~±3° and the sheet size deviation within ±2.5mm; S2: Mold preparation: Clean the mold surface and apply release agent; S3: Laying: Lay the prepreg layer by layer according to the laying table. After each layer is laid, vacuum precompact it. The vacuum degree of vacuum precompacting is -100KPa to -80KPa, and the holding time is not less than 15 minutes. After the last layer is laid, vacuum compact it. The vacuum degree of vacuum compaction is -100KPa to -85KPa, and the holding time is not less than 1 hour. S4: Packaging: Vacuum bags are made using vacuum curing auxiliary materials for packaging. After vacuuming, the vacuum degree is tested. The vacuum degree decay value should not be greater than 5 kPa within 15 minutes. S5: Curing: Place the packaged mold into an oven and set the curing parameters for curing; S6: Demolding: Demold the product after it has cooled; S7: Cutting and trimming: Cutting and trimming the product; S8: Quality inspection.

[0004] Optionally, in S1, the outer packaging is not allowed to be opened or damaged during the material thawing process. If the packaging bag is found to be damaged during the handling process, it must be sealed immediately with tape, and the start time and end time of the material thawing must be recorded.

[0005] Optionally, in S1, when the prepreg is a unidirectional prepreg, the fiber direction angle deviation is ±2°; when the prepreg is a fabric prepreg, the fiber direction angle deviation is ±3°.

[0006] Optionally, in S1, if the cut sheets are not planned to be laid within 48 hours, they need to be bagged and stored back in the freezer, and thawed again before the laying process begins.

[0007] Optionally, in S2, the mold is first used or cleaned with a cleaning agent and then coated with release agent 5 times. After each part is demolded, release agent is applied 3 times, with an interval of at least 15 minutes between each application. The next process is carried out at least 30 minutes after the last application of release agent.

[0008] Optionally, in step S2, for areas where it is inconvenient to apply release agent, a fluorinated release cloth with adhesive backing is applied to ensure the release effect.

[0009] Optionally, in S3, a scraper and a blower are used to assist heating along the fiber direction to remove air bubbles and smooth out wrinkles during installation, and scissors or a utility knife are used to remove prepreg outside the installation area.

[0010] Optionally, in S3, the backing release paper and release film are retained during the laying process, and the number and verification are carried out after laying to ensure that no inclusions or foreign objects are formed.

[0011] Optionally, in S3, the prepreg is a carbon fiber fabric prepreg with a single layer thickness of 0.22 mm and a layup of [±45 / (0 / 90) / ±45]n.

[0012] Optionally, in S4, the vacuum degree detection method is as follows: turn on the vacuum pump to remove the air from the vacuum bag membrane. When the pressure value of all detection points is -100KPa to -85KPa, stop vacuuming. If the vacuum degree decay value of all detection points is not greater than 5KPa within 15 minutes, it is considered qualified. If the decay value is greater than 5KPa, check for leaks and fill them with sealing strips, and then repeat the vacuum degree detection operation.

[0013] Optionally, in S5, the remaining working life of the material is ensured to be >0h before the laying process is completed; and the remaining mechanical property life of the material is ensured to be >0h before the heating equipment is turned on for curing.

[0014] Optionally, in step S5, the curing parameters are 2h@85℃+2h@120℃, and the product is removed from the oven when the temperature drops below 60℃.

[0015] Optionally, in S6, a nylon release wedge is gradually inserted along the gap between the edge of the part and the mold, and gently pried to separate the part from the mold.

[0016] Optionally, in S8, the quality inspection includes: visually inspecting areas with low resin content, fiber wrinkles / creases / cracks / scratches, integrity of the release fabric, dry spots / surface pores, areas with high resin content, and areas with fiber deformation and twisting, and circling the defective areas with a white paint pen.

[0017] This application also provides a composite material cap, which is laid and cured by vacuum bag pressing using the method described above. Attached Figure Description

[0018] Figure 1 The diagram shown is a flowchart illustrating a cap forming method according to this application. Figure 2 This is shown as another flowchart of a cap forming method according to this application; Figure 3 This is shown as another flowchart of a cap forming method according to this application; Figure 4 This is shown as another flowchart of a cap forming method according to this application; Figure 5 This is another flowchart illustrating a cap forming method according to this application. Detailed Implementation

[0019] 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.

[0020] 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.

[0021] 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.

[0022] The term "aircraft" is defined as an air transport system of any size having at least one lift propeller as its propulsion source. The term "aircraft" can include both "manned" and "unmanned" air transport systems. A manned aircraft can mean an air transport system carrying one or more human passengers, none of whom have control over the aircraft. A manned aircraft can also mean an air transport system carrying one or more human passengers, some of whom, or one of whom, has partial or full control over the aircraft. An unmanned aircraft can mean an air transport system that does not carry any human passengers and flies autonomously or is remotely controlled by someone at a distance.

[0023] In this specification, "aircraft" includes manned aircraft and any unmanned vehicle, such as unmanned aerial vehicles (UAVs), unmanned aircraft, remote-controlled aircraft, unmanned aircraft systems, any aircraft classified by the International Civil Aviation Organization (ICAO) under cycle 328AN / 190, and so on. As an example, a drone can take the form of a single- or multi-rotor helicopter (such as a quadcopter) or a fixed-wing aircraft. Furthermore, certain portions of this disclosure can be used in conjunction with drones in the form of other types of unmanned vehicles (e.g., wheeled, tracked, and / or watercraft).

[0024] The embodiments of this application are described below with reference to the accompanying drawings. These embodiments detail a cap molding method of the present invention and the specific implementation of the composite material cap prepared therefrom.

[0025] I. Preparation of main ingredients The main material used in this embodiment is carbon fiber fabric prepreg, which is a medium-temperature curing epoxy resin-based carbon fiber fabric prepreg suitable for OOA process. Different areal densities and fiber specifications of fabric prepregs can be selected according to specific design requirements.

[0026] Prepregs typically require freezing for extended shelf life, generally at temperatures below -18°C, to prevent significant chemical reactions in the resin system. After removing the material from the freezer, first check the expiration date on the packaging to ensure it hasn't exceeded the specified storage period. Simultaneously, check the remaining operating life and remaining mechanical property life. Operating life refers to the maximum time the prepreg can maintain good layability at room temperature; beyond this time, resin viscosity increases, leading to layability difficulties and decreased interlayer adhesion. Mechanical property life refers to the maximum time the prepreg can maintain the designed mechanical properties of the cured product after being left at room temperature. Before starting any process, ensure the material's remaining operating life is greater than 0 hours and its remaining mechanical property life is greater than 0 hours; otherwise, the material cannot be used.

[0027] After removing the material, proceed with the thawing process. The prepreg should not be opened immediately after being removed from the frozen environment; otherwise, moisture in the air will condense into water droplets on the low-temperature prepreg surface. If this moisture enters the interlayer of the prepreg, it will form bubbles and pores during subsequent curing, severely affecting the mechanical properties and appearance quality of the product. Therefore, the thawing time should be no less than 8 hours. The specific time can be appropriately extended depending on the material packaging size and freezing temperature. For large rolls or thick packaging materials, the thawing time can be extended to more than 12 hours. Thawing is considered complete when no more water droplets or moisture condense on the outer packaging after wiping it dry. During thawing, it is strictly forbidden to open or damage the outer packaging to avoid moisture condensation on the prepreg surface. If the packaging bag is found to be damaged during handling, the damaged area must be sealed immediately with tape to prevent external moisture and impurities from entering. The start and end times of thawing should be recorded to trace the material's temperature history and remaining lifespan.

[0028] After thawing, the fabric is prepared using an automatic fabric cutter according to a preset feeding program. The automatic fabric cutter boasts advantages such as high cutting precision, high efficiency, and good repeatability, effectively ensuring the consistency of fabric sheet size and the accuracy of fiber orientation. When cutting prepreg, the roll length edge must strictly coincide with the machine's 0° line to ensure the fiber orientation is consistent with the cutting direction, a prerequisite for accurate layup angles. For unidirectional prepreg, the fiber orientation angle deviation is controlled within ±2°; for woven prepreg, due to the orthogonal warp and weft characteristics of the fabric weaving structure, the fiber orientation angle deviation can be relaxed to within ±3°. The allowable size deviation of the fabric sheet is ±2.5mm. This deviation range ensures that the sheet completely covers the mold surface during layup without causing material waste due to excessive size or incomplete layup due to insufficient size.

[0029] After the prepreg sheets are cut, their quantity and markings should be checked one by one. Each sheet should be labeled with the name of the part it belongs to, the drawing number, the layup sequence, and other information to ensure correct identification and use during the installation process and to prevent confusion between sheets for different parts or layups. After verification, the sheets should be packaged and transferred to the installation station. If installation is not planned to begin within 48 hours, the cut sheets should be bagged separately and immediately returned to the freezer to prevent excessive depletion of the prepreg's operational and mechanical lifespan due to prolonged exposure to room temperature. Before the installation process begins, the sheets must be removed and thawed according to the above requirements.

[0030] II. Mold Preparation The mold is one of the key factors determining the final dimensional accuracy and surface quality of the cap. In this embodiment, a male or female mold that matches the shape of the cap is used. The mold material can be metal (such as steel or aluminum) or composite material, selected according to the production batch and accuracy requirements. For small-batch trial production, aluminum alloy molds can be used, while steel molds are preferred for mass production to ensure dimensional stability.

[0031] The first step in mold preparation is to confirm that the mold is in normal working order and record the mold number for traceability. Check that the mold markings and scribing lines are complete and clear; these markings and scribing lines are used as positioning references during installation and as reference boundaries for subsequent cutting.

[0032] Cleaning the mold surface is crucial for ensuring smooth demolding and surface quality of the finished product. Use a white cotton cloth dampened with a suitable amount of cleaning agent, along with a plastic scraper, to remove dust, adhesive residue, and other contaminants from the mold surface. The white cloth makes it easy to observe the cleaning progress and avoids secondary contamination. For stubborn stains that are difficult to remove, the amount of cleaning agent can be increased appropriately, or the stains can be gently scraped off with a plastic scraper. However, care must be taken to avoid scratching the mold surface, especially on the contoured areas of precision molds; metal scrapers are strictly prohibited. After cleaning, use a vacuum cleaner with a brush to remove any remaining dust and debris from the mold surface, ensuring the mold surface is clean and dust-free.

[0033] Before applying the release agent, use masking tape to isolate and protect the area where the bag-making sealing strip will be applied, preventing the release agent from contaminating the area and affecting the adhesion and airtightness of the subsequent sealing strip. Applying the release agent is a crucial step in ensuring the product can be smoothly removed from the mold. Since release agents typically contain organic solvents, they produce an irritating odor during application. Operators must wear masks, gloves, and protective eyewear to avoid inhaling solvent vapors or skin contact. Furthermore, applying the release agent is prohibited in the laying room; it should be done in a dedicated, well-ventilated area to prevent organic solvent vapors from diffusing into the laying room, affecting the cleanliness, temperature, and humidity of the laying environment, and consequently impacting the quality of the prepreg laying.

[0034] For molds used for the first time or thoroughly cleaned with a cleaning agent, five coats of release agent are required. This is because new molds or deeply cleaned molds have no release agent residue on their surface, necessitating the establishment of a complete release agent film. After the first coat, wait at least 15 minutes for the solvent in the release agent to fully evaporate before applying the second coat, and so on. After each subsequent part is demolded, some release agent residue may remain on the mold surface. Applying three coats of release agent will restore a complete release film, again with at least 15 minutes between each coat. After the final coat of release agent, wait at least 30 minutes before proceeding to the next step to ensure the release agent is completely dry and forms a continuous and dense release layer. For areas on the mold where applying release agent is inconvenient, such as the bottom of deep cavities, the sides of narrow grooves, or complex curved recessed areas, apply an adhesive-backed fluorinated release cloth to ensure effective demolding. Fluorine-containing release cloth has excellent non-stick and temperature resistance properties, which can effectively prevent the product from sticking to the mold in these hard-to-coat areas and avoid product damage during demolding.

[0035] If a mold that has completed the application of the release agent is not to be laid out temporarily and needs to be placed in an area outside the laying room, a clean polyethylene film should be used to cover the surface of the mold to prevent dust and impurities from falling onto the mold surface and contaminating the release agent layer.

[0036] III. Laying Laying is a core process that determines the final fiber orientation and internal quality of the cap. In this embodiment, carbon fiber fabric prepreg is used, with a nominal single-layer thickness of 0.22 mm. The layup scheme is [±45 / (0 / 90) / ±45]n, where n is a positive integer. The specific number of layups can be determined according to the design thickness requirements of the cap. For example, when n=2, the total thickness is approximately 1.76 mm, and when n=3, the total thickness is approximately 2.64 mm.

[0037] During the installation process, operators lay the prepreg layer by layer in the order specified in the layup chart. After each layer of prepreg is laid, it is necessary to visually check whether the fiber direction is consistent with the angle marked in the layup chart. For fabric prepreg, it should be confirmed that the warp and weft yarn directions conform to the design requirements, usually by observing the yarn direction at the edge of the fabric or by using an angle gauge for auxiliary measurement. If the angle deviation is found to be outside the allowable range, the prepreg should be removed and repositioned immediately.

[0038] During the application process, use a scraper in conjunction with a hairdryer for added heat, applying even pressure along the fiber direction to remove air bubbles generated during application, while simultaneously combing and smoothing any wrinkles that may appear. The moderate heat provided by the hairdryer (usually to 40-50°C) reduces the resin viscosity, making the prepreg softer and more conforming, facilitating application to complex curved surfaces, and also aiding in the removal of interlayer gas. Any excess prepreg outside the application area should be trimmed along the mold edge or positioning lines using scissors or a utility knife.

[0039] During the application process, the backing release paper and release film should be retained until the prepreg is accurately positioned on the mold before being removed to prevent accidental adhesion between prepreg layers or the accumulation of dust and impurities. After each layer is applied, the number of layers should be counted and checked to ensure it matches the layup table. Simultaneously, the applied area should be visually inspected to ensure no foreign matter (such as release paper fragments, glove fibers, hair, etc.) is mixed between the prepreg layers. These foreign objects will become interlayer defects, severely reducing the interlayer shear strength of the product.

[0040] Vacuum pre-compacting is performed according to the layer sequence required in the layup table, for example, after every 2-3 layers. The specific procedure is as follows: Place the release liner, porous release film, and breathable felt sequentially on the surface of the prepreg. Then cover with a vacuum bag film and seal it around the mold using sealing strips. Connect the vacuum lines and turn on the vacuum pump to create a vacuum. The required vacuum level for pre-compacting is -100 kPa to -80 kPa (gauge pressure), and the duration should be no less than 15 minutes. The purpose of vacuum pre-compacting is to compact the prepreg layer by layer during the layup process, expel trapped gas between layers, reduce porosity in the final product, and also help eliminate minor wrinkles that occur during prepreg laying.

[0041] After the final layer is laid, a vacuum bag is constructed using vacuum curing auxiliary materials for final vacuum compaction. Unlike the intermediate vacuum pre-compaction, the final vacuum compaction uses a non-porous release membrane to prevent resin from seeping out under pressure and contaminating the breathable felt during subsequent curing. The vacuum level required for the final vacuum compaction is -100 kPa to -85 kPa, and the holding time is no less than 1 hour. The longer holding time helps to fully expel trace amounts of gas remaining between the prepreg layers and achieves closer contact between the prepreg layers, creating favorable conditions for resin flow and fiber impregnation during the subsequent curing process.

[0042] IV. Packaging Sealing is a crucial step in ensuring the vacuum bag maintains a reliable and long-lasting seal during the curing process. As required, place part labels (for product identification), thermocouples (for temperature monitoring during curing), and vacuum extraction points (for connecting vacuum lines) in appropriate locations on the mold. Assemble the vacuum bag using vacuum curing aids for sealing.

[0043] The specific encapsulation process is as follows: On the surface of the prepreg that has been finally compacted, release cloth, non-porous release film, and breathable felt are laid in sequence, and then a vacuum bag film is placed over it. A high-performance sealing strip is used to seal the vacuum bag film to the mold. The sealing strip should be continuous and uninterrupted, with appropriate overlap at corners to ensure airtightness. When laying the vacuum bag film, pleats (i.e., folding the excess of the vacuum bag film) should be evenly and symmetrically placed around the edge of the mold, typically one pleat every 200-300 mm, so that the vacuum bag film can freely deform to conform to the shape of the product during vacuuming without causing excessive stress concentration or tearing.

[0044] Turn on the vacuum pump to remove air from the vacuum bag membrane. Stop vacuuming when the pressure at all test points reaches -100KPa to -85KPa. Then perform a vacuum test: the vacuum decay value at all test points should not exceed 5KPa within 15 minutes. Vacuum decay is an important quantitative indicator of the vacuum bag's sealing performance; the smaller the decay value, the more reliable the seal. If the decay value is greater than 5KPa, it indicates a leak in the vacuum bag system. A thorough inspection is needed to check for pinholes in the vacuum bag membrane, loose vacuum pipe joints, aging or cracked vacuum quick-connect suction cups, and poor compaction of the sealing strips at the mold edges, among other potential leak points. During the inspection, you can use auditory judgment (a hissing sound is usually heard at the leak point) or apply soapy water to the suspected area and observe for bubbles to pinpoint the leak. Once a leak is found, use yellow sealing strips to locally fill and reinforce the leak, then re-vacuum and repeat the vacuum test until the decay value is within acceptable limits before proceeding to the next step.

[0045] V. Curing Curing is the process of transforming prepreg from a viscous flow state to a cross-linked, cured thermosetting state. This process directly determines the cross-linking density of the resin and the final mechanical properties of the product. Before turning on the heating equipment for curing, it is essential to reconfirm that the remaining mechanical life of the material is greater than 0 hours. This is because the material has been stored at room temperature for a certain period of time from the preparation of the main material to the completion of the application and encapsulation, and its mechanical life may have been reduced. It is crucial to ensure that this value is still positive before curing; otherwise, the cured product will not achieve the designed strength.

[0046] The mold, after sealing and vacuum testing, is placed into the oven. The oven should have a programmed temperature rise function, capable of precisely controlling the temperature according to the preset heating rate and holding time, with a temperature control accuracy generally required to be within ±2℃.

[0047] Connect the vacuum tubing and thermocouple. The vacuum tubing is used to continuously evacuate the vacuum throughout the curing process, maintaining a stable vacuum level within the vacuum bag. This ensures that the resin fully impregnates the fibers and removes residual volatiles under vacuum pressure during curing. The thermocouple is used to monitor the temperature of the product surface or mold surface in real time, ensuring that the curing temperature remains within the set range and preventing insufficient or over-curing due to temperature deviations.

[0048] After entering the oven, a vacuum test is performed again. The testing method is exactly the same as the packaging process: when the pressure value at the vacuum test point reaches -100KPa to -85KPa, vacuuming is stopped, and the vacuum pressure at the test point must not decrease by more than 5KPa within 15 minutes. If the decrease value is greater than 5KPa, the leak point needs to be investigated and repaired, and the test is repeated until it passes, ensuring that the vacuum pressure will not decrease due to leakage during the curing process.

[0049] The curing regime used in this embodiment is: 2 hours @ 85℃ + 2 hours @ 120℃. First, the oven is heated to 85℃ at a rate not exceeding 2℃ / min, and held at this temperature for 2 hours to allow the resin system to complete initial gelation and partial cross-linking reactions, while low-boiling-point volatiles are fully released during this stage. Then, the temperature is further increased to 120℃ at a rate not exceeding 2℃ / min, and held for 2 hours to fully cure the resin, achieving the designed cross-linking density and glass transition temperature. Throughout the curing process, the vacuum pump operates continuously to maintain the vacuum pressure inside the vacuum bag at no less than -85 kPa.

[0050] After curing, turn off the heating power and allow the product to cool naturally in the oven. Remove the product from the oven only after the temperature has dropped below 60℃. There are two reasons for removing the product from the oven only after the temperature has dropped below 60℃: first, to avoid thermal deformation or warping of the product due to the difference in thermal expansion coefficients between the product and the mold when demolding at high temperatures; and second, to prevent burns to operators when removing the product.

[0051] VI. Demolding After the product is taken out of the oven, wait for it to cool to room temperature naturally. Do not demold before the product has completely cooled to room temperature, because the difference in thermal expansion coefficients between the product and the mold in the hot state will cause them to bond tightly. Forcing demolding can easily cause the product to crack or be scratched on the surface.

[0052] After the temperature drops 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, neatly coil the thermocouple wires, clean the vacuum connectors, and place them in designated locations for reuse in subsequent processes.

[0053] Use a nylon release wedge to gradually insert it along the seam between the part and the mold, and gently pry to separate the part from the mold. Nylon is much less hard than mold steel or aluminum alloy, so it won't scratch the mold surface, and its good toughness makes it less prone to breakage. When prying, apply force evenly at multiple points along the edge of the part, starting with areas of lower stress concentration such as corners or midpoints of the edge, and gradually expanding the separation area. Avoid applying excessive force in a single location, which could cause localized cracking or stress whitening of the product. For caps with complex shapes or high sticking force, it may be necessary to pry alternately and repeatedly from multiple directions until the product is completely removed from the mold.

[0054] After demolding, use a plastic scraper or cotton cloth to clean the small amount of residual resin residue on the mold surface, keeping the mold surface clean and preparing for the next molding.

[0055] VII. Cutting and trimming After demolding, the cap product usually has burrs and excess rough edges around its perimeter. This is an inevitable product of resin seeping out along the edge of the mold during the vacuum bag compression molding process, and it needs to be cut and trimmed.

[0056] Use manual cutting to remove excess burrs along the mold markings or product boundary lines. Maintain a straight and continuous cutting path during operation to avoid jagged edges or damage to the product itself. Use a ruler to guide the cutting of straight edges, and carefully cut along the markings for curved edges.

[0057] Use 240-grit or finer sandpaper to sand burrs and rough marks left from cutting on the edges of the parts. Using finer sandpaper (240 grit or higher) ensures smooth and even edges after sanding, preventing new scratches, fuzzing, or delamination. Sanding should be done unidirectionally along the edge to avoid rounding the edges due to repeated back-and-forth sanding. After sanding, thoroughly clean the surface of the product with a clean non-woven cloth or compressed air to remove dust and sanding debris.

[0058] VIII. Quality Inspection After cutting, trimming, and cleaning, a comprehensive quality inspection is conducted on the product. All inspection items are carried out visually, supplemented by necessary lighting tools (such as handheld LED lights). When problems are found, the location of the defect is circled on the product surface with a white marker, and the type and size of the defect are recorded.

[0059] The inspection items include: (1) visually inspecting for areas with low resin content, i.e., areas where the fibers are exposed and the resin content is obviously insufficient to completely cover the fibers. Such areas appear dry and whitish; (2) visually inspecting for defects such as fiber wrinkles, creases, cracks, or scratches that damage the integrity of the fibers. These defects will significantly reduce the tensile and compressive strength of the product; (3) visually inspecting whether the release cloth is completely laid. If there is any damage, the location and extent of the damage should be recorded. Damage to the release cloth may result in local areas without an isolation layer, causing resin adhesion; (4) visually inspecting for dry spots or surface pores. Dry spots are characterized by local areas lacking resin and the fibers appearing as dry powder. Surface pores are characterized by round pits the size of a pinhead; (5) visually inspecting for areas with high resin content, i.e., areas where the resin is concentrated and the fiber volume fraction is obviously low. Such areas have an appearance with a gloss level that is significantly higher than the surrounding areas; (6) visually inspecting for areas where the fibers are deformed or twisted, i.e., areas where the fiber direction deviates from the design angle beyond the allowable range. For the above-mentioned defects, it is necessary to determine whether the product is qualified according to the acceptance limits specified in the design drawings and acceptance standards. Qualified products shall enter the subsequent process, and unqualified products shall be disposed of in accordance with the relevant quality procedures.

[0060] 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 a lid, characterized in that, Includes the following steps: S1: Main material preparation: Remove the prepreg from the frozen environment and check the remaining operating life and remaining mechanical property life of the material to ensure that the remaining operating life is >0h and the remaining mechanical property life is >0h; Thaw the material for no less than 8 hours. Thawing is considered complete when no more water droplets / moisture condense after wiping the outer packaging dry; Cut the prepreg using an automatic fabric cutter, controlling the fiber direction angle deviation within ±2°~±3° and the sheet size deviation within ±2.5mm; S2: Mold preparation: Clean the mold surface and apply release agent; S3: Laying: Lay the prepreg layer by layer according to the laying table. After each layer is laid, vacuum precompact it. The vacuum degree of vacuum precompacting is -100KPa to -80KPa, and the holding time is not less than 15 minutes. After the last layer is laid, vacuum compact it. The vacuum degree of vacuum compaction is -100KPa to -85KPa, and the holding time is not less than 1 hour. S4: Packaging: Vacuum bags are made using vacuum curing auxiliary materials for packaging. After vacuuming, the vacuum degree is tested. The vacuum degree decay value should not be greater than 5 kPa within 15 minutes. S5: Curing: Place the packaged mold into an oven and set the curing parameters for curing; S6: Demolding: Demold the product after it has cooled; S7: Cutting and trimming: Cutting and trimming the product; S8: Quality inspection.

2. The cap forming method according to claim 1, characterized in that, In S1, the outer packaging must not be opened or damaged during the thawing of the material. If the packaging bag is found to be damaged during the handling process, it must be sealed immediately with tape, and the start time and end time of the thawing of the material must be recorded.

3. The cap forming method according to claim 1, characterized in that, In S1, when the prepreg is a unidirectional prepreg, the fiber direction angle deviation is ±2°; when the prepreg is a fabric prepreg, the fiber direction angle deviation is ±3°.

4. The cap forming method according to claim 1, characterized in that, In S1, if the cut sheets are not planned to be laid within 48 hours, they need to be bagged and stored back in the freezer, and thawed again before the laying process begins.

5. The cap forming method according to claim 1, characterized in that, In S2, the mold is first used or cleaned with a cleaning agent and then coated with release agent 5 times. After each subsequent part is demolded, release agent is applied 3 times, with an interval of at least 15 minutes between each application. The next process is carried out at least 30 minutes after the last application of release agent.

6. The cap forming method according to claim 1, characterized in that, In step S2, for areas where it is inconvenient to apply release agent, fluorine-containing release cloth with adhesive backing is laid to ensure the release effect.

7. The cap forming method according to claim 1, characterized in that, In step S3, a scraper and a blower are used to assist in heating during the application process, removing air bubbles and smoothing out wrinkles along the fiber direction. Scissors or a utility knife are used to remove the prepreg outside the application area.

8. The cap forming method according to claim 1, characterized in that, In S3, the backing release paper and release film are retained during the laying process, and the number and check are performed after laying to ensure that no impurities or foreign objects are formed.

9. The cap forming method according to claim 1, characterized in that, In S3, the prepreg is a carbon fiber fabric prepreg with a single layer thickness of 0.22 mm and a layup of [±45 / (0 / 90) / ±45]n.

10. The cap forming method according to claim 1, characterized in that, In S4, the vacuum degree detection method is as follows: turn on the vacuum pump to remove the air from the vacuum bag membrane. When the pressure value of all detection points is -100KPa to -85KPa, stop vacuuming. If the vacuum degree decay value of all detection points is not greater than 5KPa within 15 minutes, it is qualified. If the decay value is greater than 5KPa, check for air leaks and fill them with sealing strips, and then repeat the vacuum degree detection operation.

11. The cap forming method according to claim 1, characterized in that, In S5, the remaining working life of the material is ensured to be >0h before the laying process is completed; the remaining mechanical property life of the material is ensured to be >0h before the heating equipment is turned on for curing.

12. The cap forming method according to claim 1, characterized in that, In step S5, the curing parameters are 2h@85℃+2h@120℃, and the product is removed from the oven when the temperature drops below 60℃.

13. The cap forming method according to claim 1, characterized in that, In step S6, a nylon release wedge is gradually inserted along the gap between the part edge and the mold, and gently pried to separate the part from the mold.

14. The cap forming method according to claim 1, characterized in that, In S8, the quality inspection includes: visually inspecting areas with low resin content, fiber wrinkles / creases / cracks / scratches, the integrity of the release fabric, dry spots / surface pores, areas with high resin content, and areas with fiber deformation and twisting, and circling the defective areas with a white paint pen.

15. A composite material cap, characterized in that, It is laid using the method described in any one of claims 1-14 and cured by vacuum bag pressing.

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