A method for forming a ribbed plate of a pitot tube and a method for laying and curing the same

Abstract

The application relates to the technical field of composite material forming, and discloses a method for forming an air speed tube rib plate, which comprises the following steps: S1, main material preparation; S2, mold preparation; S3, auxiliary material preparation; S4, laying and pasting; S5, packaging; S6, curing; S7, demolding; and S8, cutting and edging.

Description

Technical Field

[0001] This application relates to the field of composite material molding technology, and in particular to a method for molding airspeed tube ribs and its laying and curing method. Background Technology

[0002] Traditional pitot tube ribs are mostly formed using autoclave molding processes, which have drawbacks such as high equipment costs, high energy consumption, and long production cycles. Furthermore, the fiber orientation accuracy and interlayer density are difficult to control stably during manual laying, affecting the consistency of the product's mechanical properties. Summary of the Invention

[0003] The purpose of this application is to provide a method for forming a pitot tube rib, including the following steps: S1: Main material preparation: Remove the prepreg material from the frozen environment and check the material's storage expiration date, remaining operating life, and remaining mechanical property life 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, and it is considered thawed when no water droplets or moisture condense after wiping the outer packaging dry; Cut the prepreg material using an automatic fabric cutter, controlling the fiber direction angle deviation within ±2° to ±3° and the sheet size deviation within ±2.5mm; S2: Mold preparation: Clean the mold surface and apply release agent. For molds used for the first time or cleaned with cleaning agent, apply 5 coats of release agent. After each part is demolded, apply 3 coats of release agent with an interval of at least 15 minutes between each coat. After the last coat is applied, wait at least 30 minutes before proceeding to the next step. S3: Preparation of auxiliary materials: Cutting auxiliary materials for vacuum pre-compression and vacuum curing; S4: Laying: At the corners and steps of the mold, lay a layer of 15mm wide prepreg fabric of the same material as the product for filling, and then use carbon fiber unidirectional fiber filaments to fill the R-corners for a smooth transition; lay the prepreg layer by layer according to the layup table, the layup structure is 0.22mm thick single layer of carbon fiber prepreg fabric, layup method [±45 / (0 / 90)]n / carbon plate / [±45 / (0 / 90)]n, where n is a positive integer; after each layer is laid, use a scraper and a blower to assist heating along the fiber direction to remove air bubbles and comb out wrinkles; during the laying process, perform at least one vacuum pre-compaction, the vacuum degree of vacuum pre-compaction is -100KPa to -80KPa, and the holding time is not less than 15 minutes; after the last layer is laid, perform vacuum compaction, the vacuum degree of vacuum compaction is -100KPa to -85KPa, and the holding time is not less than 1 hour; S5: Packaging: Place the part label, thermocouple and vacuum evacuation point, use vacuum curing auxiliary material to assemble a vacuum bag for packaging, evacuate to the pressure value of each detection point -100KPa to -85KPa and then stop evacuating, the vacuum degree decay value should not be greater than 5KPa within 15 minutes. S6: Curing: Send the packaged mold into the oven, connect the vacuum pipeline and thermocouple, and perform vacuum degree test again. After confirming that the vacuum degree decay value is not greater than 5KPa within 15 minutes, set the curing parameters and perform curing. S7: Demolding: After the product temperature drops to room temperature, remove the auxiliary materials and use nylon demolding wedges to separate the parts from the mold; S8: Cutting and trimming: Cut and drill holes according to the engraved lines, grind off burrs on the edges and clean the product surface.

[0004] Optionally, in step S1, if the cut pieces are not planned to be laid within 48 hours, they are bagged and stored back in the freezer, and then thawed before the laying process begins.

[0005] Optionally, in step S2, before applying the release agent, the dust and adhesive residue on the surface of the mold and tooling are cleaned with a white cotton cloth, cleaning agent, plastic scraper and vacuum cleaner, and the sealing strip area for bag making is isolated and protected with masking tape.

[0006] Optionally, in step S2, for localized areas where it is inconvenient to apply release agent, a fluorinated release cloth with adhesive backing is laid to ensure the release effect; if the mold after the release agent application is completed is placed outside the paving area, the mold surface must be covered with a film.

[0007] Optionally, in S3, the auxiliary materials for vacuum pre-compression include a porous release membrane, a release cloth, a breathable felt, and a vacuum bag film; the auxiliary materials for vacuum curing include a release cloth, a non-porous release membrane, a breathable felt, and a vacuum bag film; the size of the vacuum bag film is cut according to the mold size after being scaled up, ensuring that it completely covers the product and the edge of the mold and leaves room for pleating.

[0008] Optionally, in S4, the seam positions are joined or overlapped according to the process specifications: the prepreg fabric overlaps in non-fitting areas with an overlap width of 25-35mm; in fitting areas, the seam gap is ≤1mm; if several consecutive layers overlap or overlap, the seam positions should be staggered by at least 25mm, and seams at the same position should be at least 4 layers apart in the thickness direction.

[0009] Optionally, in step S4, after each layer of prepreg is laid, it is necessary to visually check whether the fiber direction is consistent with the angle inside the layup surface, and use scissors or a utility knife to remove the prepreg outside the laying area; during the laying process, the backing release paper and release film are retained, and after the laying is completed, the number is counted and checked to ensure that no inclusions are formed and to confirm that there are no foreign objects.

[0010] Optionally, in step S4, when using a large area of ​​core material for paving, expanding foam is used to fill the seams between the core materials.

[0011] Optionally, before step S4, a pre-laying inspection step is also included: checking that the ambient temperature is 22±4℃ and the humidity is ≤60%, checking that the measuring instruments are within the calibration validity period, checking that the remaining operating life and remaining mechanical property life of the raw materials meet the requirements, and checking that the mold information is correct and the accessories are complete.

[0012] Optionally, in step S6, the curing parameters are: 2 hours at 85°C plus 2 hours at 120°C; the product is removed from the oven when the temperature drops below 60°C.

[0013] Optionally, in step S8, cutting is performed according to manual cutting requirements, and burrs on the edges of the parts are removed using sandpaper of 240 grit or higher.

[0014] Optionally, after S8, an appearance quality inspection step is also included: visually inspecting the product for areas with low resin content, fiber wrinkles, creases, cracks or scratches, damaged release cloth, dry spots or surface pores, areas with high resin content, and areas with deformed or twisted fibers. If any defects are found, they are circled on the product surface with a white paint pen.

[0015] Optionally, it also includes a quality inspection step: requesting the quality department to conduct a quality inspection; and a warehousing step: warehousing qualified parts.

[0016] Optionally, in step S5, if the vacuum degree decay value is greater than 5 kPa, then check for leaks in the vacuum bag film, vacuum pipeline, vacuum quick-connect suction cup, and mold. After filling the leaks with yellow sealing strips, repeat the vacuum degree test operation.

[0017] This application also provides a method for laying and curing pitot tube ribs, including: SA: Laying process: Use a 15mm wide prepreg of the same material as the product to fill the corners and steps of the mold, and then use carbon fiber unidirectional fiber to fill the R-corners and smooth the transition; lay the prepreg layer by layer according to the layup table. The layup structure is 0.22mm thick carbon fiber prepreg and the layup method is [±45 / (0 / 90)]n / carbon plate / [±45 / (0 / 90)]n, where n is a positive integer; after each layer is laid, use a scraper and a blower to assist heating along the fiber direction to remove air bubbles and comb wrinkles; the overlap width of the seam in the non-fitting area is 25-35mm, the gap in the fitting area is ≤1mm, the seam positions are staggered by at least 25mm and are at least 4 layers apart in the thickness direction; SB: Vacuum pre-compaction: Vacuum pre-compaction shall be performed at least once during the laying process, with a vacuum degree of -100KPa to -80KPa, and the time shall not be less than 15 minutes; SC: Vacuum compaction: After the last layer is laid, vacuum compaction is carried out with a vacuum degree of -100KPa to -85KPa and a holding time of not less than 1 hour; SD: Packaging and vacuum degree testing: Place part labels, thermocouples and vacuum extraction points, make vacuum bags for packaging, and stop after evacuating to -100KPa to -85KPa. The vacuum degree decay value should not be greater than 5KPa within 15 minutes. Curing: After placing the product in the oven and confirming that the vacuum level decreases by no more than 5 kPa within 15 minutes, the product is cured at 85℃ for 2 hours and 120℃ for 2 hours. The product is removed from the oven when the temperature drops below 60℃. SE: Demolding: After naturally cooling to room temperature, remove auxiliary materials and use nylon demolding wedges to separate the parts from the mold; SF: Cutting and trimming: Cut and drill holes according to the engraved lines, use 240 grit or higher sandpaper to sand the edges and clean the product surface. Attached Figure Description

[0018] Figure 1 The diagram shows a flow chart of a method for forming a pitot tube rib according to this application. Figure 2 This is another flowchart illustrating a method for forming a pitot tube rib according to this application. Figure 3 This is another flowchart illustrating a method for forming a pitot tube rib according to this application. Figure 4 This is another flowchart illustrating a method for forming a pitot tube rib according to this application. Figure 5 The diagram shows a flow chart of a method for laying and curing a pitot tube rib plate 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 the specific implementation of a method for forming an airspeed tube rib and its laying and curing method.

[0025] I. Preparation of main ingredients The pitot tube ribs use carbon fiber prepreg as the main structural material. The prepreg is stored at low temperatures to maintain its processing properties, typically below -18°C. In the main material preparation step, the required carbon fiber prepreg material is first removed from the frozen environment. The storage expiration date marked on the material packaging is checked, along with the remaining operating life and remaining mechanical property life. Operating life refers to the time window during which the prepreg remains operable at room temperature after being removed from the frozen environment; mechanical property life refers to the time period during which the prepreg's mechanical properties do not decrease after final curing, from the completion of production until curing. To ensure molding quality, the remaining operating life of the material must be greater than 0 hours, and the remaining mechanical property life must also be greater than 0 hours.

[0026] Material thawing is a crucial step in prepreg preparation. After removing the prepreg from the frozen environment, the thawing time should be no less than 8 hours. During thawing, the outer packaging must not be opened or damaged to prevent moisture in the air from condensing on the prepreg surface. Moisture intrusion can adversely affect the interfacial bonding between the resin matrix and the fiber. Thawing is considered complete when no more water droplets or moisture condense on the surface after wiping the outer packaging dry. If the packaging bag is found to be damaged during handling, the damaged area must be sealed immediately with tape to prevent external moisture from entering the packaging. The start and end times of thawing should be recorded to track the material's operational lifespan.

[0027] After thawing, the prepreg is prepared using an automatic fabric cutting machine according to a preset cutting program. When cutting the prepreg, the length edge of the roll must coincide with the machine's 0° line to ensure the fiber direction angle deviation is controlled within the specified range. Specifically, the fiber direction angle deviation for unidirectional prepreg is generally ±2°, and for woven prepreg, it is generally ±3°; the allowable dimensional deviation of the sheet is ±2.5mm. After cutting, the quantity and marking information of the sheets are checked. The sheet packaging is marked with the part name, drawing number, and other information before being transferred to the laying station. If laying is not planned to begin within 48 hours, the cut sheets should be bagged separately and stored in a frozen environment, then thawed again before the laying process begins. This measure effectively prevents excessive wear and tear on the prepreg's operational life caused by prolonged exposure to room temperature.

[0028] II. Mold Preparation The purpose of mold preparation is to ensure that the mold surface is clean and has good demolding performance, providing a reliable molding foundation for subsequent laying and curing. First, confirm that the mold is in normal condition, record the mold number, and confirm that the markings and engravings on the mold are complete and clear. These markings and engravings are important references for subsequent laying, positioning, cutting, and trimming; their clarity directly affects the dimensional accuracy of the product.

[0029] For mold cleaning, use a white cotton cloth and cleaning agent to wipe the mold. For stubborn adhesive residue, carefully scrape it off with a plastic scraper. Finally, use a vacuum cleaner to remove dust and residue from the mold and tooling surfaces. After cleaning, use masking tape to isolate and protect the sealing strip area used for bag making to prevent contamination of the sealing area when applying release agent later, which could affect the sealing effect of the vacuum bag.

[0030] The application of release agent should be carried out outside the tiling area. Operators must wear masks, gloves, and safety glasses for safety. New molds used for the first time or molds thoroughly cleaned with a cleaning agent require five coats of release agent; after each subsequent demolding, three coats should be applied. Allow at least 15 minutes between each coat to ensure sufficient solvent evaporation and uniform curing of the release agent film. Wait at least 30 minutes after the final coat before proceeding to the next step. For areas on the mold where application of release agent is inconvenient, apply fluorinated release cloth with adhesive backing to ensure effective demolding in these areas. Molds that have undergone release agent application, if placed outside the tiling area, must be covered with a thin film to prevent dust contamination.

[0031] III. Preparation of Auxiliary Materials Auxiliary materials are an indispensable part of the vacuum bag forming process. Depending on the specific steps, two sets of auxiliary materials are required.

[0032] The first group consists of practical auxiliary materials for vacuum preloading, including a porous release membrane, a release cloth, a breathable felt, and a vacuum bag film. The porous release membrane has evenly distributed small holes, allowing air to escape smoothly during the vacuuming process; the release cloth is in contact with the prepreg and is easy to peel off after curing; the breathable felt provides airflow channels to ensure uniform air pressure throughout the vacuum bag; and the vacuum bag film acts as a sealing layer, isolating the entire system from the outside atmosphere.

[0033] The second group consists of auxiliary materials for vacuum curing, including release cloth, non-porous release film, breathable felt, and vacuum bag film. Unlike pre-compaction, the release film for curing is non-porous to prevent resin loss during the curing process. The cutting area of ​​the auxiliary materials is determined based on the area to be applied to the part. The size of the vacuum bag film needs to be calculated based on the mold size before cutting to ensure complete coverage of the product and mold edges, with sufficient allowance for pleating during bag making. The pleats are designed to allow the vacuum bag film to shrink freely with the product shape during vacuuming, preventing rupture or local bridging caused by excessive stretching of the bag film.

[0034] IV. Pre-laying inspection Before officially starting the tiling process, a series of checks need to be conducted to ensure that the tiling environment, equipment, and materials all meet the process requirements.

[0035] Regarding environmental checks, it was confirmed that the temperature in the installation room was within the range of 22±4℃ and the relative humidity was ≤60%, and environmental parameters were recorded. Temperature and humidity have a significant impact on the viscosity and service life of prepregs. Excessively high or low temperatures will affect the installation operability of prepregs, while excessively high humidity may cause moisture to condense on the surface of the prepreg.

[0036] Regarding the inspection of measuring instruments, it is confirmed that the measuring instruments used (such as thermometers, hygrometers, vacuum gauges, etc.) are in a usable condition and within the calibration validity period.

[0037] Regarding raw material inspection, it was reconfirmed that the remaining operating life and mechanical property life of the raw materials met the process requirements. Since a certain amount of time may have passed between the preparation of the main materials and the start of the installation, the operating life may have been consumed, so this reconfirmation before installation is essential.

[0038] Regarding mold inspection, confirm that the mold information is correct and that all accessories such as bolts and movable parts are complete. Missing accessories may prevent the mold from closing or positioning properly during the installation process.

[0039] V. Laying Laying is the core process in the pitot tube rib forming method, which directly affects the internal quality and dimensional accuracy of the product.

[0040] First, localized filling is performed. In areas prone to hollowing or bridging, such as corners and steps in the mold, a 15mm wide layer of prepreg fabric of the same material as the product is applied for filling. Then, carbon fiber unidirectional filaments are used for filling according to the size of the part's radius, creating a smooth transition in the corner areas. The purpose of this treatment is to prevent the prepreg from failing to fully adhere to the mold surface at sharp corners, thereby preventing hollowing or resin buildup after curing.

[0041] Regarding seam treatment, butt joints or overlaps are performed according to process specifications. Generally, prepreg fabrics are overlapped in non-fitting areas with an overlap width of 25–35 mm; butt joints are used in fitting areas with a butt joint gap ≤ 1 mm. If several consecutive layers overlap or butt joint, the seam positions between different layers should be staggered by at least 25 mm, and seams at the same location should be separated by at least 4 layers in the thickness direction. This staggered seam design effectively avoids stress concentration and improves the structural integrity of the product.

[0042] When laying the prepreg layer by layer, visually check that the fiber direction matches the angle marked on the layup sheet after each layer. After laying, use a scraper and a hairdryer to assist heating, pushing out air bubbles generated during the laying process along the fiber direction, and simultaneously smoothing out wrinkles. Heating temporarily reduces the resin viscosity, making it easier to expel air bubbles and flatten the fibers. Use scissors or a utility knife to remove excess prepreg outside the laid area.

[0043] When using large-area core material, expandable foam should be used to fill the seams between the core materials. The expandable foam expands during the curing process, effectively filling the gaps and preventing resin buildup or voids at the core material seams.

[0044] During the installation process, the backing release paper and release film should be retained, and counted and checked after installation. This step aims to ensure that all release paper and release film have been removed, no inclusions have formed, and that no foreign matter has entered the layup. The presence of foreign matter can create defects and severely affect the mechanical properties of the product.

[0045] Vacuum precompacting should be performed according to the layer sequence required in the layup table. Vacuum bags should be made using vacuum precompacting auxiliary materials. The vacuum level required for vacuum precompacting is -100 kPa to -80 kPa, and the holding time should not be less than 15 minutes. The purpose of vacuum precompacting is to compact the laid prepreg layer by layer during the laying process, expel air between layers, and improve the interlayer bonding quality.

[0046] After the final layer is applied, vacuum bags are fabricated using vacuum compaction auxiliary materials according to the sealing procedure. The vacuum bags should have evenly and symmetrically arranged pleats. The required vacuum level for compaction is -100 kPa to -85 kPa, and the duration should be no less than 1 hour. Prolonged vacuum compaction helps to fully remove residual air between the prepreg layers and prepares the material for subsequent curing.

[0047] The reference pneumatic tube rib structure is as follows: carbon fiber prepreg, single layer thickness 0.22mm, ply pattern [±45 / (0 / 90)]n / carbon plate / [±45 / (0 / 90)]n. Where n is a positive integer, determined according to design load requirements. The ±45° ply provides shear and torsional stiffness, the (0 / 90) ply provides bending and tensile stiffness, and the intermediate carbon plate layer serves as a reinforcing layer to improve overall stiffness.

[0048] VI. Packaging After the bonding is completed, the encapsulation process begins. Component labels are placed as required for traceability, thermocouples are installed for temperature monitoring and control during curing, and vacuum extraction points are set up to remove air from the vacuum bags. Vacuum bags are then constructed using vacuum curing auxiliary materials for encapsulation.

[0049] After sealing, perform a vacuum test. Turn on the vacuum pump to remove air from the vacuum bag membrane. Stop vacuuming when the pressure at all test points reaches -100 kPa to -85 kPa. The vacuum decay at all test points should not exceed 5 kPa within 15 minutes. Vacuum decay is a crucial indicator of the vacuum bag's sealing performance; excessively rapid decay indicates a leak. If the decay value exceeds 5 kPa, check the vacuum bag membrane, vacuum tubing, vacuum quick-connect suction cups, mold, etc., for leaks. If a leak is found, fill it with yellow sealing strips and then repeat the vacuum test.

[0050] VII. Curing Curing is a key process that causes the resin in the prepreg to undergo a cross-linking reaction and form the final mechanical properties.

[0051] Before turning on the heating equipment for curing, it must be confirmed again that the remaining mechanical life of the material is greater than 0 hours. This is a prerequisite for ensuring that the mechanical properties of the cured product meet the standards.

[0052] The mold, after sealing, is placed into the oven. Vacuum lines and thermocouples are connected to continuously collect vacuum and temperature data during the curing process, enabling real-time monitoring of the curing process.

[0053] After entering the oven, a vacuum test is performed. Vacuuming is stopped when the pressure at the vacuum test point reaches -100 kPa to -85 kPa. The vacuum level at the test point should not decrease by more than 5 kPa within 15 minutes. If the decrease exceeds 5 kPa, leaks in the vacuum bag film, vacuum tubing, vacuum quick-connect suction cups, and molds must be investigated. Leaks should be filled with sealing strips, and the vacuum test should be repeated. Vacuum testing in an oven environment is particularly important because the flexibility of the vacuum bag film changes with temperature; areas that are leak-free at room temperature may leak at high temperatures.

[0054] The curing parameters were set as follows: 2 hours at 85℃ followed by 2 hours at 120℃. The first stage of 85℃ curing allows the resin system to initially cure at a lower temperature, reducing viscosity and allowing it to fully flow and wet the fibers. The second stage of 120℃ curing allows the resin to complete cross-linking and achieve the designed mechanical properties. This two-stage curing process helps reduce exothermic peaks during curing and avoids thermal stress concentration.

[0055] After curing, the product temperature must drop below 60℃ before it can be removed from the oven. The purpose of controlling the oven temperature is to prevent the product from deforming or cracking due to thermal stress when demolded at a high temperature.

[0056] 8. Demolding Wait for the product temperature to drop to room temperature naturally. Remove auxiliary materials such as vacuum bag film, breathable felt, non-porous isolation film, release cloth, and sealing strips from the surface of the parts. Remove the thermocouples and vacuum connectors and clean them. Place them in designated locations for reuse.

[0057] Using a nylon release wedge, gradually insert it along the seam between the part and the mold, and gently pry to separate the part from the mold. The nylon material is less hard than the mold and the part, and will not damage the surfaces of either. After demolding, clean any residual adhesive from the mold surface to prepare for the next part production.

[0058] 9. Cutting and trimming Cut the demolded product according to the manual cutting requirements. Drill holes according to the engraving lines on the mold. Use 240-grit sandpaper to smooth out burrs from the edges of the parts. Finally, clean the dust off the product surface.

[0059] 10. Appearance Quality Inspection After cutting and trimming, a surface quality inspection is performed. Visually inspect the parts for the following defects: areas lacking resin, fiber wrinkles or creases, cracks or scratches on damaged fibers, torn release fabric, dry spots or surface pores, areas rich in resin, and areas of fiber deformation or twisting. If any of these defects are found, mark them on the product surface with a white paint pen. The surface quality inspection is a comprehensive examination of the product's appearance quality; the marked defective areas provide a basis for possible subsequent repairs or assessments.

[0060] XI. Quality Inspection and Warehousing After the appearance quality inspection is passed, the product is submitted to the Quality Department for quality inspection. Quality inspection includes dimensional checks and non-destructive testing to confirm that the product meets all requirements of the design drawings and technical specifications. The inspected and qualified parts are then put into storage.

[0061] 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 pitot tube rib, characterized in that, Includes the following steps: S1: Main material preparation: Remove the prepreg material from the frozen environment and check the material's storage expiration date, remaining operating life, and remaining mechanical property life 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, and it is considered thawed when no water droplets or moisture condense after wiping the outer packaging dry; Cut the prepreg material using an automatic fabric cutter, controlling the fiber direction angle deviation within ±2° to ±3° and the sheet size deviation within ±2.5mm; S2: Mold preparation: Clean the mold surface and apply release agent. For molds used for the first time or cleaned with cleaning agent, apply 5 coats of release agent. After each part is demolded, apply 3 coats of release agent with an interval of at least 15 minutes between each coat. After the last coat is applied, wait at least 30 minutes before proceeding to the next step. S3: Preparation of auxiliary materials: Cutting auxiliary materials for vacuum pre-compression and vacuum curing; S4: Laying: At the corners and steps of the mold, lay a layer of 15mm wide prepreg fabric of the same material as the product for filling, and then use carbon fiber unidirectional fiber filaments to fill the R-corners for a smooth transition; lay the prepreg layer by layer according to the layup table, the layup structure is 0.22mm thick single layer of carbon fiber prepreg fabric, layup method [±45 / (0 / 90)]n / carbon plate / [±45 / (0 / 90)]n, where n is a positive integer; after each layer is laid, use a scraper and a blower to assist heating along the fiber direction to remove air bubbles and comb out wrinkles; during the laying process, perform at least one vacuum pre-compaction, the vacuum degree of vacuum pre-compaction is -100KPa to -80KPa, and the holding time is not less than 15 minutes; after the last layer is laid, perform vacuum compaction, the vacuum degree of vacuum compaction is -100KPa to -85KPa, and the holding time is not less than 1 hour; S5: Packaging: Place the part label, thermocouple and vacuum evacuation point, use vacuum curing auxiliary material to assemble a vacuum bag for packaging, evacuate to the pressure value of each detection point -100KPa to -85KPa and then stop evacuating, the vacuum degree decay value should not be greater than 5KPa within 15 minutes. S6: Curing: Send the packaged mold into the oven, connect the vacuum pipeline and thermocouple, and perform vacuum degree test again. After confirming that the vacuum degree decay value is not greater than 5KPa within 15 minutes, set the curing parameters and perform curing. S7: Demolding: After the product temperature drops to room temperature, remove the auxiliary materials and use nylon demolding wedges to separate the parts from the mold; S8: Cutting and trimming: Cut and drill holes according to the engraved lines, grind off burrs on the edges and clean the product surface.

2. The method for forming the airspeed tube rib according to claim 1, characterized in that, In step S1, if the cut pieces are not planned to be laid within 48 hours, they are bagged and stored back in the freezer, and then thawed before the laying process begins.

3. The method for forming the airspeed tube rib according to claim 1, characterized in that, In step S2, before applying the release agent, the dust and adhesive residue on the surface of the mold and tooling are cleaned with a white cotton cloth, cleaning agent, plastic scraper and vacuum cleaner, and the sealing strip area for bag making is isolated and protected with masking tape.

4. The method for forming the airspeed tube rib according to claim 1, characterized in that, In step S2, for localized areas where it is inconvenient to apply release agent, adhesive-backed fluorinated release cloth is laid to ensure the release effect; if the mold after the release agent application is completed is placed outside the paving area, the mold surface must be covered with a film.

5. The method for forming the airspeed tube rib according to claim 1, characterized in that, In S3, the auxiliary materials for vacuum pre-compression include a porous release membrane, a release cloth, a breathable felt, and a vacuum bag film; the auxiliary materials for vacuum curing include a release cloth, a non-porous release membrane, a breathable felt, and a vacuum bag film; the size of the vacuum bag film is cut according to the mold size after being scaled up, ensuring that it completely covers the product and the edge of the mold and leaves room for pleating.

6. The method for forming the airspeed tube rib according to claim 1, characterized in that, In S4, the seam positions are joined or overlapped according to the process specifications: the prepreg fabric overlaps in non-fitting areas with an overlap width of 25-35mm; in fitting areas, the seam gap is ≤1mm; if several consecutive layers overlap or overlap, the seam positions should be staggered by at least 25mm, and seams in the same position should be at least 4 layers apart in the thickness direction.

7. The method for forming the airspeed tube rib according to claim 1, characterized in that, In step S4, after each layer of prepreg is laid, it is necessary to visually check whether the fiber direction is consistent with the angle inside the layup surface. Use scissors or a utility knife to remove the prepreg outside the laying area. During the laying process, retain the backing release paper and release film. After the laying is completed, count and check to ensure that no inclusions are formed and confirm that there are no foreign objects.

8. The method for forming the airspeed tube rib according to claim 1, characterized in that, In S4, when using large-area core material for paving, expanding foam is used to fill the seams between the core materials.

9. The method for forming the airspeed tube rib according to claim 1, characterized in that, Before S4, there are also pre-laying inspection steps: checking that the ambient temperature is 22±4℃ and the humidity is ≤60%, checking that the measuring instruments are within the calibration validity period, checking that the remaining operating life and remaining mechanical property life of the raw materials meet the requirements, and checking that the mold information is correct and the accessories are complete.

10. The method for forming the airspeed tube rib according to claim 1, characterized in that, In step S6, the curing parameters are: 2 hours at 85°C plus 2 hours at 120°C; the product is removed from the oven when the temperature drops below 60°C.

11. The method for forming the airspeed tube rib according to claim 1, characterized in that, In step S8, cutting is performed according to manual cutting requirements, and burrs on the edges of the parts are polished using sandpaper of 240 grit or higher.

12. The method for forming the airspeed tube rib according to claim 1, characterized in that, The S8 step includes an appearance quality inspection step: visually inspect the product for areas with low resin content, fiber wrinkles, creases, cracks or scratches, damaged release cloth, dry spots or surface pores, areas with high resin content, and areas with deformed or twisted fibers. If any defects are found, they are circled on the product surface with a white paint pen.

13. The method for forming the airspeed tube rib according to claim 1, characterized in that, It also includes a quality inspection step: requesting the quality department to conduct a quality inspection; and a warehousing step: putting qualified parts into the warehouse.

14. The method for forming the airspeed tube rib according to claim 1, characterized in that, In step S5, if the vacuum degree decay value is greater than 5 kPa, check for leaks in the vacuum bag film, vacuum pipeline, vacuum quick-connect suction cup, and mold. After filling the leaks with yellow sealing strips, repeat the vacuum degree test operation.

15. A method for laying and curing a pitot tube rib, characterized in that, include: SA: Laying process: Use a 15mm wide prepreg of the same material as the product to fill the corners and steps of the mold, and then use carbon fiber unidirectional fiber to fill the R-corners and smooth the transition; lay the prepreg layer by layer according to the layup table. The layup structure is 0.22mm thick carbon fiber prepreg and the layup method is [±45 / (0 / 90)]n / carbon plate / [±45 / (0 / 90)]n, where n is a positive integer; after each layer is laid, use a scraper and a blower to assist heating along the fiber direction to remove air bubbles and comb wrinkles; the overlap width of the seam in the non-fitting area is 25-35mm, the gap in the fitting area is ≤1mm, the seam positions are staggered by at least 25mm and are at least 4 layers apart in the thickness direction; SB: Vacuum pre-compaction: Vacuum pre-compaction shall be performed at least once during the laying process, with a vacuum degree of -100KPa to -80KPa, and the time shall not be less than 15 minutes; SC: Vacuum compaction: After the last layer is laid, vacuum compaction is carried out with a vacuum degree of -100KPa to -85KPa and a holding time of not less than 1 hour; SD: Packaging and vacuum degree testing: Place part labels, thermocouples and vacuum extraction points, make vacuum bags for packaging, and stop after evacuating to -100KPa to -85KPa. The vacuum degree decay value should not be greater than 5KPa within 15 minutes. SE: Curing: After sending the product into the oven and confirming that the vacuum degree decay value is not greater than 5KPa within 15 minutes, the product is cured with curing parameters of 2 hours @ 85℃ plus 2 hours @ 120℃. The product is taken out of the oven when the temperature drops below 60℃. SF: Demolding: After naturally cooling to room temperature, remove auxiliary materials and use nylon release wedges to separate the parts from the mold; SG: Cutting and trimming: Cut and drill holes according to the engraved lines, use 240 grit or higher sandpaper to sand the edges and clean the product surface.

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