Preparation method of aero-engine composite material fan blade

Abstract

The invention discloses a preparation method of an aero-engine composite material fan blade in the technical field of composite material molding, and the preparation method comprises the following steps: S1, providing a carbon fiber reinforced epoxy resin prepreg and cutting to obtain a prepreg sheet; s2, after the blade paving mold is cleaned, the surface of the blade paving mold is coated with a release agent, and mold preparation is completed; and S3, a shape-following pressing mold matched with the molded surface of the upper surface of the blade is manufactured, and the shape-following pressing mold is subjected to layer laying and vacuum compaction and then is cured and formed. The T800-grade high-strength one-way and plain carbon fibers are selected as reinforcements and the high-temperature epoxy resin is selected as a matrix to prepare the prepreg, and the 1500D aramid fiber lines are adopted to carry out X-shaped Z-direction sewing on the laminated blade blank, so that the specific strength, the specific stiffness and the interlayer shear strength of the blade are effectively improved, the problem that a traditional laminated plate is easy to layer is solved, and the production efficiency is improved. And the requirements of light weight and high performance of the blade are met.

Description

Technical Field

[0001] This invention relates to the field of composite material molding technology, and more specifically, to a method for preparing composite material fan blades for aero-engines. Background Technology

[0002] Aero-engine fan blades are core components ensuring engine operating efficiency and aircraft flight safety. As the aviation industry continuously raises the requirements for technical indicators such as engine bypass ratio and thrust-to-weight ratio, blades must simultaneously meet stringent demands for lightweight, high strength, and high containment performance. Composite materials, due to their advantages such as light weight, high specific strength, and energy absorption after impact, have gradually become the preferred material for fan blades. Their molding quality directly determines the performance and reliability of the blades.

[0003] In existing technologies, the fabrication of fan blades mainly falls into two categories: one is the processing and forming of traditional metal materials, and the other is the fabrication of composite material blades through composite material layup and simple curing processes. While traditional metal material blades possess certain high-temperature resistance and corrosion resistance, they struggle to meet current high performance requirements in terms of lightweighting and specific strength. Some composite material blades are formed through basic layup and curing processes without optimizing key aspects such as interlayer bonding and component adhesion.

[0004] However, existing manufacturing techniques still have certain problems in practical applications: on the one hand, traditional metal blades are heavy, which increases the overall energy consumption of the aircraft, and their impact resistance is poor, which can easily cause serious impact to the engine casing; on the other hand, existing composite blades have low interlaminar shear strength, which can easily lead to delamination during use, and the bonding reliability between components is insufficient, which can easily lead to the risk of detachment after long-term service, affecting the service life of the blades and flight safety. Therefore, we urgently need a manufacturing method for composite fan blades for aero-engines to solve the above problems. Summary of the Invention

[0005] One objective of this invention is to provide a new technical solution for the preparation of composite material fan blades for aero-engines. By laying up T800 grade carbon fiber prepreg, Z-direction stitching of aramid fibers, titanium alloy edge binding, pickling and bonding, and precision autoclave curing, the specific strength of the blades is improved, delamination is prevented, molding accuracy and bonding reliability are ensured, and the requirements for lightweight and high performance are met.

[0006] The objective of this invention is achieved as follows: a method for preparing composite material fan blades for aero-engines, comprising the following steps:

[0007] S1: Provide carbon fiber reinforced epoxy resin prepreg and cut it to obtain prepreg sheets;

[0008] S2: After cleaning the blade laying mold, apply a release agent to its surface to complete the mold preparation;

[0009] S3: Fabricate a conformal mold that matches the profile of the upper surface of the blade. The conformal mold is solidified after being laid up and vacuum compacted.

[0010] S4: The cut prepreg is laid layer by layer on the mold, and the layup is stitched together in the Z direction using high-strength fiber thread. The stitched body is then fitted with the mold and vacuum sealed before being cured together in an autoclave to obtain the composite material blade.

[0011] S5: Provide a metal leading edge edging and perform surface treatment on it, then glue it to the leading edge of the composite material blade and cure it;

[0012] S6: Apply primer and topcoat sequentially to the blade surface.

[0013] Optionally, in the carbon fiber reinforced epoxy resin prepreg, the carbon fiber is high-strength unidirectional carbon fiber or high-strength plain weave carbon fiber, and the epoxy resin is high-temperature epoxy resin.

[0014] Optionally, in step S2, the preparation of the blade laying mold includes wiping and cleaning with organic solvent, and the release agent is applied no less than 3 times, with an interval of no less than 15 minutes between adjacent applications.

[0015] Optionally, in step S3, the conformal molding layer structure includes a rubber film and a plain prepreg. During the layering process, each layer is vacuum compacted in sequence and then cured in an autoclave.

[0016] Optionally, in step S4, the layer-by-layer laying of the prepreg is assisted by laser positioning, and a pre-vacuuming process is performed after every 1-5 layers are laid, with a pre-vacuuming time of not less than 15 minutes.

[0017] Optionally, in step S4, the high-strength fiber thread is an aramid fiber thread, and the Z-direction stitching adopts a cross stitching pattern, with the stitching position covering the leading edge, trailing edge, and tip of the blade.

[0018] Optionally, in step S5, the metal leading edge is edged with titanium alloy, and the surface treatment includes sequential alkaline washing and pickling. The pickling solution is composed of nitric acid and hydrofluoric acid, with the nitric acid concentration being 150 ml / L to 250 ml / L and the hydrofluoric acid concentration being 20 ml / L to 50 ml / L.

[0019] Optionally, in step S5, the bonding area of ​​the composite material blade and the metal leading edge edge is ground before bonding, and then cleaned with an organic solvent after grinding.

[0020] Optionally, in step S5, the adhesive used for bonding is a paste-like adhesive, and the curing after bonding is carried out by oven heating and curing at a temperature of 70℃~90℃ for 1h~2h.

[0021] Optionally, in step S6, the primer is an epoxy primer, the topcoat is a polyurethane topcoat, and both the primer and the topcoat are applied in 2 to 3 coats, with each coat being dried after application.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. According to an embodiment of this disclosure, the method for preparing the composite material fan blade of the aero-engine involves using T800 grade high-strength unidirectional and plain weave carbon fiber as reinforcement and high-temperature epoxy resin as matrix to prepare prepreg, and using 1500D aramid fiber yarn to perform "X"-shaped Z-direction stitching on the laminated blade blank, which effectively improves the specific strength, specific stiffness and interlaminar shear strength of the blade, solves the problem of easy delamination of traditional laminates, and meets the requirements of lightweight and high performance of the blade.

[0024] 2. According to one embodiment of this disclosure, the method for preparing the composite material fan blade of the aero-engine uses a blade laying mold made of 45# steel, combined with a conformal molding die with a structure of "AirPad rubber soft film + T800 plain weave prepreg + AirPad rubber soft film", and combined with preset autoclave curing, heating, pressurization and heat preservation parameters, to ensure the dimensional accuracy and structural compactness of the blade during the forming process, and avoid mold deformation or defects such as pores and wrinkles in the blade.

[0025] 3. According to one embodiment of this disclosure, the preparation method of the composite material fan blade for aero-engine involves sequentially treating the titanium alloy leading edge edge with alkaline washing at 70°C and 10% NaOH aqueous solution to remove oil, followed by acid washing with a solution composed of 150ml / L~250ml / L nitric acid and 20ml / L~50ml / L hydrofluoric acid. After polishing with 180-grit sandpaper and cleaning with anhydrous ethanol, the edge edge is bonded with J-357X paste adhesive and cured in an oven. This enhances the bonding reliability between the edge edge and the composite material blade body, and improves the impact resistance and corrosion resistance of the blade leading edge.

[0026] 4. According to one embodiment of this disclosure, the method for preparing the composite material fan blade of the aero-engine involves preparing TH06-81 epoxy primer and TS96-71 polyurethane topcoat according to the specified ratio, controlling the paint viscosity to be 18s to 22s, applying 2 to 3 coats at a spray gun pressure of 0.4MPa and a spraying distance of 200-300mm, and drying at 60°C for 6 hours after each coat and inspecting and repairing defects. This significantly improves the corrosion resistance, wear resistance, and weather resistance of the blade, and extends the service life of the blade. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0028] Figure 1 This is a flowchart of the present invention.

[0029] Figure 2 This is a schematic diagram of the engine composite material fan blade of the present invention.

[0030] Figure 3 This is a schematic diagram of the upper pressure mold of the present invention.

[0031] Figure 4 This is a schematic diagram of the blade laying mold of the present invention.

[0032] Figure 5 This is a schematic diagram of the suturing process of the present invention.

[0033] Figure 6 This is a schematic diagram of the edge-binding adhesive bonding of the present invention.

[0034] The following are marked in the diagram: 1. Fan blade body; 2. Titanium alloy leading edge edging; 3. Upper pressing mold; 4. Lifting lug; 5. Upper pressing mold base plate; 6. Target hole; 7. Tenon insert; 8. Laying surface; 9. Blade tip insert; 10. Blade stitching track. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] like Figure 1-6 As shown, a method for preparing a composite material fan blade for an aero-engine includes the following steps:

[0037] S1: Provide carbon fiber reinforced epoxy resin prepreg and cut it to obtain prepreg sheets.

[0038] Here, an automatic cutting machine is used to cut the carbon fiber reinforced epoxy resin prepreg according to a pre-drawn pattern, which can achieve precise cutting of the prepreg sheet, ensure that the sheet size is consistent with the design requirements, and improve cutting efficiency.

[0039] Furthermore, the reinforcement of the carbon fiber reinforced epoxy resin prepreg is made of high-strength T800 grade carbon fiber (specifically TG800HC-12K unidirectional carbon fiber and TG800H-6K plain weave carbon fiber), and the matrix material is high-temperature epoxy resin E1806. T800 grade carbon fiber has excellent mechanical properties, and when combined with high-temperature epoxy resin E1806, the high strength characteristics of carbon fiber can be maximized, providing a good mechanical foundation for the blade.

[0040] Furthermore, after cutting, the information and quantity of the prepreg sheets are checked to ensure they meet the preset requirements, thus avoiding abnormalities in subsequent layup processes due to incorrect sheet information or missing quantities, and ensuring the continuity and reliability of the preparation process.

[0041] In carbon fiber reinforced epoxy resin prepreg, the carbon fiber is high-strength unidirectional carbon fiber or high-strength plain weave carbon fiber, and the epoxy resin is high-temperature epoxy resin.

[0042] Here, the high-strength unidirectional carbon fiber is model TG800HC-12K, the high-strength plain weave carbon fiber is model TG800H-6K, and the high-temperature epoxy resin is specifically E1806 epoxy resin. Specifying the specific material model can ensure the stability and consistency of material performance, thus guaranteeing the quality of blade forming.

[0043] Furthermore, based on the selected materials, TG800H / E1806 unidirectional prepreg and TG800H200P / E1806 plain weave prepreg were respectively manufactured. The two prepregs are adapted to the performance requirements of different parts of the blade, improving the rationality of the overall blade structure and mechanical properties.

[0044] Furthermore, the resin content and thickness uniformity of the prepreg are strictly controlled during the manufacturing process to avoid affecting the strength and stiffness of the blade due to uneven resin content or thickness deviation, thus ensuring the dimensional accuracy and performance stability of the blade after molding.

[0045] S2: After cleaning the blade laying mold, apply a release agent to its surface to complete the mold preparation.

[0046] Here, medical gauze is used to apply an appropriate amount of acetone to the laying surface 8 of the leaf laying mold and wipe it clean until the gauze is no longer obviously discolored. Acetone can effectively remove oil, impurities and other contaminants from the mold surface, ensuring the cleanliness of the mold surface and avoiding affecting the adhesion between the prepreg and the mold and the quality of the leaf forming.

[0047] Furthermore, after cleaning, the mold should be left to air dry at room temperature for at least 15 minutes to ensure that any residual acetone on the mold surface has completely evaporated, thus preventing the acetone from reacting with the subsequently applied release agent and ensuring the effectiveness of the release agent coating.

[0048] Furthermore, 770NC release agent is selected. A suitable amount of release agent is applied to the mold surface using medical gauze. 770NC release agent is suitable for composite material molding processes. After application, it can form a uniform protective film on the mold surface, ensuring smooth demolding after the blade is formed, without affecting the surface quality of the blade.

[0049] In step S2, the preparation of the blade laying mold includes wiping and cleaning with organic solvent, applying the release agent no less than 3 times, and the interval between two adjacent applications is no less than 15 minutes.

[0050] Here, the organic solvent is acetone. Each time the release agent is applied, the mold surface is fully covered without any missed areas. Acetone has strong cleaning ability and can thoroughly remove impurities from the mold surface. Multiple full-coverage applications of the release agent can ensure the uniformity of the release film thickness and improve the reliability of demolding.

[0051] Furthermore, the interval between two consecutive coats of release agent should be controlled at more than 15 minutes to ensure that the previous coat of release agent is completely dry before the next coat is applied. This avoids the mixing of undried release agent, which can lead to uneven film layers and prevent problems such as mold sticking and damage to the blade surface during demolding.

[0052] Furthermore, after coating, check the mold release agent film layer on the mold surface for defects such as bubbles and pinholes. If any are found, recoat the film layer in time to ensure the integrity of the release agent film layer, further improve the demolding effect, and ensure that the blade surface is smooth and flawless.

[0053] S3: Make an upper pressure mold 3 that matches the upper surface profile of the blade. The upper pressure mold 3 is solidified and formed after being laid up and vacuum compacted.

[0054] Here, a molding die is designed according to the shape of the upper surface of the blade. The upper molding die 3 includes a lifting lug 4, an upper molding die base plate 5, and a layered structure. A layer of AirPad rubber soft film is first laid on the molding die, and then it is pressed and flattened using a rolling pin. The AirPad rubber soft film has good flexibility and can fit tightly to the molding die surface. Pressing and flattening can prevent air bubbles from forming between the soft film and the die, providing a good basic flexible layer for the upper molding die 3.

[0055] Furthermore, two layers of T800 plain weave prepreg in the 0° direction are laid on the rubber film, and then a layer of AirPad rubber film is laid. After each layer is laid, it is compacted with a rolling pin. The two layers of T800 plain weave prepreg can ensure the structural strength and rigidity of the upper molding die 3. The outer rubber film can be precisely matched with the upper surface of the blade. The multi-layer compaction can avoid gaps between layers.

[0056] Furthermore, after the layers are laid, auxiliary materials such as release film, breathable felt and vacuum bag film are laid on the surface in sequence, and sealing strips are used to seal the surface. Vacuum compaction is then performed on the upper mold 3. The auxiliary materials ensure that the gas can be discharged smoothly during the vacuum compaction process, the sealing strips ensure the stability of the vacuum environment, and the vacuum compaction can further eliminate air bubbles between the layers of the upper mold 3 and improve the structural density of the upper mold 3.

[0057] In step S3, the layup structure of the upper pressure mold 3 includes a rubber soft film and a plain prepreg. During the layup process, each layer is vacuum compacted in sequence and then cured in a hot autoclave.

[0058] Here, the vacuum degree of the vacuum compaction process is controlled at -0.095MPa to -0.1MPa, and the vacuuming time is 15min. This vacuum degree and vacuuming time can fully remove the air between the layers, avoid the generation of pores inside the upper mold 3, and ensure that the layers of the upper mold 3 are tightly bonded.

[0059] Furthermore, during autoclave curing, the temperature is increased at a rate of 0.5℃ / min to 2.0℃ / min. When the thermocouple reaches 40℃, the pressure is increased to 1.0±0.02MPa at a rate of 0.02MPa / min and kept constant. Slow heating and pressurization can avoid stress concentration caused by sudden temperature and pressure changes in the upper mold 3, and prevent deformation or damage to the upper mold 3. The constant pressure state ensures stable pressure during the curing process.

[0060] Furthermore, the medium temperature is set to 135℃. When the thermocouple reaches 125℃ at the slowest temperature rise, it is kept at that temperature for 1-1.5 hours. Then, the medium temperature is set to 190℃. When the thermocouple reaches 180℃ at the slowest temperature rise, it is kept at that temperature for 2-3 hours. Finally, it is cooled to below 60℃ at a rate not exceeding 2.5℃ / min before depressurization and opening the can. The segmented heating and holding process allows the upper mold 3 to fully solidify, improving its mechanical properties and dimensional stability. Slow cooling prevents the upper mold 3 from cracking due to excessive temperature difference.

[0061] S4: The cut prepreg is laid layer by layer on the blade laying mold. The blade laying mold includes tenon insert 7, laying surface 8 and blade tip insert 9. High-strength fiber thread is used to sew the laying body in the Z direction. Then the sewn body is matched with the upper pressing mold 3 and vacuum sealed. After that, it is cured together in a thermostatic jar to obtain the fan blade body 1.

[0062] Here, during the installation, the prepreg sheets are laid layer by layer on the installation surface 8 of the blade installation mold according to the preset order of the sheets and the outline projected by the laser projector. There are a total of 290 sheets. Laser positioning can achieve precise installation of the prepreg sheets and ensure that the position of each layer of sheets is aligned. The 290-layer layup design can meet the mechanical performance requirements of the fan blade body 1.

[0063] Furthermore, during the paving process, after the first layer is laid and every five layers thereafter, a pre-vacuum treatment is performed to remove air between the layers in a timely manner, reduce interlayer bubbles, and improve the structural density of the fan blade body 1.

[0064] Furthermore, after the Z-direction stitching is completed, the blade is reinstalled into the blade laying mold and the upper pressing mold 3 is placed. Auxiliary materials such as peelable cloth, release film, breathable felt and medium-temperature vacuum bag film are sequentially laid on the surface of the blank. High-temperature sealing strips are used for vacuum sealing. The auxiliary materials can ensure that gas and excess resin are discharged during the autoclave curing process. Vacuum sealing ensures a stable curing environment. The upper pressing mold 3 can provide uniform pressure to the fan blade body 1.

[0065] In step S4, the prepreg is laid layer by layer with laser positioning assistance, and a pre-vacuuming process is performed after every 1-5 layers, with a pre-vacuuming time of not less than 15 minutes.

[0066] Here, laser positioning is achieved through the target hole 6 on the blade laying mold. The projected outline perfectly matches the preset shape of the sheet. The target hole 6 can improve the accuracy of laser positioning, ensure that the prepreg sheet is laid without deviation, and guarantee the accuracy of the blade profile.

[0067] Furthermore, the vacuum level of the pre-vacuum treatment is controlled between -0.095MPa and -0.1MPa, and the pre-vacuum time is 15 minutes each time. This vacuum parameter can fully remove the air between the layers, avoid the formation of pores between the layers, and improve the interlayer bonding force.

[0068] Furthermore, during the pre-vacuuming process, check for problems such as wrinkling or misalignment in the layup. If any are found, adjust them promptly to identify and address layup defects in a timely manner, thus preventing the accumulation of defects from affecting the forming quality and mechanical properties of the fan blade body 1.

[0069] In step S4, the high-strength fiber thread is aramid fiber thread, and the Z-direction stitching adopts a cross stitching pattern, with the stitching position covering the leading edge, trailing edge and tip of the blade.

[0070] Here, the aramid fiber thread is 1500D specification, and the cross-stitch pattern is specifically "X". The 1500D aramid fiber thread has high strength and good toughness. The "X" stitch can form a stable stitch structure, effectively improving the interlaminar shear strength of the fan blade body 1.

[0071] Furthermore, a sewing machine is used during sewing, and the sewing pattern is adjusted to an "X" shape. The sewing is performed evenly along the leaf sewing trajectory 10. The sewing machine ensures uniform sewing density, and the leaf sewing trajectory 10 ensures accurate sewing position, avoiding missed or over-sewing.

[0072] Furthermore, after the stitching is completed, check whether the stitching is loose or broken to ensure the quality of the stitching and avoid interlayer separation of the fan blade body 1 during subsequent curing or use due to stitching defects, thus ensuring the structural integrity of the fan blade body 1.

[0073] S5: Provide a titanium alloy leading edge edging 2 and perform surface treatment on it, then glue it to the leading edge of the fan blade body 1 and cure it.

[0074] Here, the titanium alloy leading edge edging 2 is made of titanium alloy. Before surface treatment, the thickness of the titanium alloy leading edge edging 2 is measured and recorded. Titanium alloy has good high temperature resistance and corrosion resistance, which is suitable for the use environment of the blade leading edge. Measuring the thickness in advance can provide a reference for subsequent pickling treatment and ensure that the thickness of the titanium alloy leading edge edging 2 meets the standard.

[0075] Furthermore, the surface treatment first involves alkaline washing to remove oil. A 10% NaOH aqueous solution is used, and the solution is heated to 70°C. The titanium alloy leading edge edging 2 is immersed in the solution for 15 minutes, and then taken out and rinsed with clean water. The 10% NaOH aqueous solution at 70°C can effectively remove oil stains from the surface of the titanium alloy leading edge edging 2, and rinsing with clean water can prevent alkaline residue from corroding the titanium alloy leading edge edging 2.

[0076] Furthermore, after alkaline washing, acid washing is performed. The titanium alloy leading edge 2 is completely immersed in the acid washing solution for 1-2 minutes. During the process, the titanium alloy leading edge 2 is continuously shaken to observe the reaction. Shaking the titanium alloy leading edge 2 can ensure that the acid washing solution is in full contact with the surface of the titanium alloy leading edge 2, ensuring that the oxide layer is removed evenly. The initial acid washing time of 1-2 minutes can avoid excessive corrosion.

[0077] In step S5, the metal leading edge is edged with titanium alloy. The surface treatment includes alkaline washing and pickling in sequence. The pickling solution is composed of nitric acid and hydrofluoric acid, with the nitric acid concentration being 150 ml / L to 250 ml / L and the hydrofluoric acid concentration being 20 ml / L to 50 ml / L.

[0078] Here, the pickling solution is prepared using 65%–68% analytical grade HNO3 and 40% analytical grade HF. The initial nitric acid concentration is 200 ml / L and the hydrofluoric acid concentration is 20 ml / L. Using analytical grade reagents ensures the accuracy of the pickling solution concentration. The initial concentration setting can reduce corrosion of the titanium alloy leading edge 2 while removing the oxide layer.

[0079] Furthermore, after pickling, remove the titanium alloy leading edge edging 2, observe whether the surface oxide has been completely removed, and measure the thickness again. If the thickness does not meet the requirement of 0.5mm±0.1mm, the pickling time can be extended to 3 minutes, or the HNO3 concentration can be increased to 250ml / L and the HF concentration to 30ml / L. Repeat the pickling process multiple times. By checking the thickness and adjusting the concentration and time, ensure that the thickness of the titanium alloy leading edge edging 2 meets the standard and that the surface oxide layer is completely removed, thus ensuring the subsequent bonding effect.

[0080] Furthermore, after the pickling meets the standards, the titanium alloy leading edge edging 2 is thoroughly cleaned with water, and the residual moisture on the surface of the titanium alloy leading edge edging 2 is dried with cold air. The water rinse removes acid residue, and the cold air drying can prevent water stains or secondary oxidation from forming on the surface of the titanium alloy leading edge edging 2.

[0081] In step S5, the bonding area of ​​the fan blade body 1 and the titanium alloy leading edge edging 2 is polished before bonding, and then cleaned with organic solvent.

[0082] Here, 180-grit sandpaper is used for sanding until the surface of the bonding area has no obvious gloss. Sanding with 180-grit sandpaper can increase the surface roughness of the bonding area, increase the contact area between the adhesive and the bonding surface, and enhance the bonding strength between the fan blade body 1 and the titanium alloy leading edge edging 2.

[0083] Furthermore, the organic solvent is anhydrous ethanol. A lint-free cloth is used to wipe and clean the bonding area after sanding with anhydrous ethanol. Anhydrous ethanol can effectively remove carbon fiber dust and other impurities generated during sanding, and it evaporates quickly without leaving any residue, thus avoiding affecting the bonding effect of the adhesive.

[0084] Furthermore, after cleaning, check the bonding area for any residual impurities or moisture to ensure that the bonding surface is clean and dry. This will prevent impurities or moisture from causing defects such as bubbles or poor adhesion in the adhesive layer, and ensure the reliability of the bonding between the fan blade body 1 and the titanium alloy leading edge edging 2.

[0085] In step S5, a paste-like adhesive is used for bonding, and the curing after bonding is carried out by oven heating at a temperature of 70℃~90℃ for 1h~2h.

[0086] Here, the paste-like adhesive is J-357X adhesive. Before use, it should be taken out of the cold storage and thawed for more than 6 hours. The adhesive is squeezed out using a glue gun and evenly applied to the bonding area using a scraper. J-357X adhesive is suitable for bonding titanium alloys and composite materials. Pre-thawing ensures the stability of the adhesive performance, and even application ensures that the thickness of the adhesive layer is consistent.

[0087] Furthermore, after the titanium alloy leading edge edging 2 is installed in place, the excess adhesive squeezed out is wiped clean with a lint-free cloth soaked in anhydrous ethanol. Then, the titanium alloy leading edge edging 2 is fixed with straps, and vacuum sealing is performed with auxiliary materials such as release film, breathable felt, and vacuum bag to remove excess adhesive and avoid affecting the appearance of the blade and subsequent processes. The straps ensure that the titanium alloy leading edge edging 2 is accurately positioned, and the vacuum sealing can remove air from the adhesive layer and improve the adhesive quality.

[0088] Furthermore, during oven curing, the temperature inside the oven is raised to 80℃ at a heating rate of 1℃ / min and then held for 1.5 hours. After the holding period, the heating is turned off, and the auxiliary materials are removed after the oven cools naturally to below 45℃. Slow heating avoids internal stress in the adhesive layer due to sudden temperature changes. Holding at 80℃ for 1.5 hours allows the adhesive to fully cure, and natural cooling to below 45℃ reduces the temperature difference stress between the adhesive layer and the blade, ensuring the bonding stability between the fan blade body 1 and the titanium alloy leading edge edging 2.

[0089] S6: Apply primer and topcoat sequentially to the blade surface.

[0090] Before spraying, masking tape is used to protect the leading edge 2 of the titanium alloy and the tenon position. Sandpaper is used to sand the blade surface until there is no obvious gloss. Then, anhydrous ethanol is used to clean it. Masking tape can prevent non-spraying areas from being contaminated. Sanding can increase the roughness of the blade surface and improve the adhesion of the paint. Anhydrous ethanol is used to clean and remove impurities to ensure the spraying effect.

[0091] Furthermore, when spraying the primer, prepare the epoxy primer according to the mixing ratio, stir it evenly, add thinner to adjust the viscosity of the paint, pour it into the paint can and spray it with a spray gun. Adjusting the viscosity can ensure that the primer is sprayed evenly and avoid defects such as sagging and pinholes.

[0092] Furthermore, after spraying the topcoat, check the paint surface of the blades for defects such as nodules, bubbles, pinholes, cracks, particles, and foreign matter. If defects are found, the corresponding area of ​​paint must be sanded clean and repainted. Timely repair of spraying defects ensures the integrity and aesthetics of the paint layer on the blade surface, and guarantees the corrosion resistance and wear resistance of the blades.

[0093] In step S6, the primer is an epoxy primer and the topcoat is a polyurethane topcoat. Both the primer and the topcoat are applied in 2 to 3 coats, and each coat is dried after application.

[0094] Here, the epoxy primer is specifically TH06-81 chromium-free high-solids epoxy primer, with a mixing ratio of component A: component B = 10:2 (by weight). The thinner is CS thinner, added at 10% of the paint weight. The paint viscosity is adjusted to 18s-22s and filtered through a 100-mesh copper mesh. TH06-81 chromium-free high-solids epoxy primer has excellent anti-corrosion performance. Precise mixing ratio and viscosity adjustment can ensure the spraying effect. Filtering through a 100-mesh copper mesh can remove impurities and particles from the paint, avoiding particle defects after spraying.

[0095] Furthermore, the polyurethane topcoat is specifically TS96-71 fluoropolyurethane matte black enamel paint, with a mixing ratio of component A: component B = 100:7 (by weight). The thinner is a special TSX-71 thinner, added at 10% of the paint weight. The paint viscosity is adjusted to 18s-22s and filtered through a 100-mesh copper screen. TS96-71 fluoropolyurethane topcoat has good weather resistance and abrasion resistance. The special thinner ensures the paint performance, and the filtration process avoids impurities affecting the spraying quality.

[0096] Furthermore, during spraying, the spray gun pressure is adjusted to 0.4MPa, the distance between the nozzle and the spraying surface is maintained at 200mm-300mm, and the spraying speed is controlled at 250mm / s-400mm / s. Two coats of primer are applied, and three coats of topcoat are applied. After each coat, the blades are sent to the drying room and dried at 60℃ for 6 hours. Precise spraying parameters ensure uniform paint layer thickness, and drying at 60℃ for 6 hours allows the paint to fully cure, improving the adhesion and durability of the paint layer. The design of two coats of primer and three coats of topcoat can meet the anti-corrosion and protection requirements of the blades.

[0097] In this invention, TG800HC-12K unidirectional carbon fiber and TG800H-6K plain weave carbon fiber are used as reinforcements, and high-temperature epoxy resin E1806 is used as the matrix. First, corresponding unidirectional and plain weave prepregs are prepared and cut by an automatic cutting machine. Using a blade-laying mold made of 45# steel as a base, after cleaning with acetone and treatment with 770NC release agent (applied at least three times with intervals of at least 15 minutes), 290 layers of prepreg are laid layer by layer according to laser positioning (using the target holes in the mold). A pre-vacuum treatment of at least 15 minutes is performed after every 5 layers. Then, 1500D aramid fiber thread is used to stitch the blades in an "X" shape along the stitching path. The blades are then sewn together and then laid in an upper mold made of “AirPad rubber film + two layers of 0° T800 plain weave prepreg + AirPad rubber film”, vacuum compacted (vacuum degree -0.095MPa to -0.1Mpa, 15min) and cured in an autoclave (heating rate 0.5℃ / min-2.0℃ / min, pressurized to 1.0±0.02MPa constant pressure after 40℃, kept at 135℃ for 1-1.5h, kept at 190℃ for 2-3h, cooling rate not greater than 2.5℃ / min to release pressure below 60℃). The fan blade body is obtained by curing in an autoclave with the same parameters.

[0098] The titanium alloy leading edge edge is first soaked in a 10% NaOH aqueous solution at 70℃ for 15 minutes to remove oil, then soaked in an acid pickling solution prepared with 65-68% analytical grade HNO3 and 40% analytical grade HF (HNO3 concentration 150-250ml / L, HF concentration 20-50ml / L) for 1-2 minutes to ensure a thickness of 0.5mm±0.1mm, then dried. After polishing with 180-grit sandpaper and cleaning with anhydrous ethanol, it is bonded to the leading edge of the blade using J-357X paste adhesive that has been thawed for more than 6 hours in advance, and cured in an oven at 80℃ for 1.5 hours. Finally, the blade is painted, first according to component A. TH06-81 epoxy primer was prepared with a component ratio of A:B=10:2. 10% CS thinner was added to adjust the viscosity to 18s-22s. Two coats were sprayed at a spray gun pressure of 0.4MPa, a spraying distance of 200mm-300mm, and a speed of 250mm / s-400mm / s. The coating was then dried at 60℃ for 6 hours. TS96-71 fluoropolyurethane topcoat was then prepared with a component ratio of A:B=100:7. 10% TSX-71 thinner was added to adjust the viscosity. Three coats were sprayed using the same spraying parameters and dried. After defect inspection, the fan blade manufacturing was completed. The synergistic effect of each process ensured the lightweight, high strength, and high containment performance of the blades.

[0099] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing composite material fan blades for aero-engines, characterized in that: Includes the following steps: S1: Provide carbon fiber reinforced epoxy resin prepreg and cut it to obtain prepreg sheets; S2: After cleaning the blade laying mold, apply a release agent to its surface to complete the mold preparation; S3: Fabricate a conformal mold that matches the profile of the upper surface of the blade. The conformal mold is solidified after being laid up and vacuum compacted. S4: The cut prepreg is laid layer by layer on the mold, and the layup is stitched together in the Z direction using high-strength fiber thread. The stitched body is then fitted with the mold and vacuum sealed before being cured together in an autoclave to obtain the composite material blade. S5: Provide a metal leading edge edging and perform surface treatment on it, then glue it to the leading edge of the composite material blade and cure it; S6: Apply primer and topcoat sequentially to the blade surface.

2. The method for preparing a composite material fan blade for an aero-engine according to claim 1, characterized in that: In the carbon fiber reinforced epoxy resin prepreg, the carbon fiber is high-strength unidirectional carbon fiber or high-strength plain weave carbon fiber, and the epoxy resin is high-temperature epoxy resin.

3. The method for preparing a composite material fan blade for an aero-engine according to claim 1, characterized in that: In step S2, the preparation of the blade laying mold includes wiping and cleaning with organic solvent, and the release agent is applied no less than 3 times, with an interval of no less than 15 minutes between adjacent applications.

4. The method for preparing a composite material fan blade for an aero-engine according to claim 1, characterized in that: In step S3, the conformal molding layer structure includes a rubber film and a plain prepreg. During the layering process, each layer is vacuum compacted in sequence and then cured in an autoclave.

5. The method for preparing a composite material fan blade for an aero-engine according to claim 1, characterized in that: In step S4, the prepreg is laid layer by layer with laser positioning assistance, and a pre-vacuuming process is performed after every 1-5 layers, with a pre-vacuuming time of not less than 15 minutes.

6. The method for preparing a composite material fan blade for an aero-engine according to claim 1, characterized in that: In step S4, the high-strength fiber thread is aramid fiber thread, and the Z-direction stitching adopts a cross stitching pattern, with the stitching position covering the leading edge, trailing edge and tip of the blade.

7. The method for preparing a composite material fan blade for an aero-engine according to claim 1, characterized in that: In step S5, the metal leading edge is edged with titanium alloy, and the surface treatment includes alkaline washing and pickling in sequence. The pickling solution is composed of nitric acid and hydrofluoric acid, with the nitric acid concentration being 150 ml / L to 250 ml / L and the hydrofluoric acid concentration being 20 ml / L to 50 ml / L.

8. The method for preparing a composite material fan blade for an aero-engine according to claim 1, characterized in that: In step S5, the bonding area of ​​the composite blade and the metal leading edge is ground before bonding, and then cleaned with an organic solvent.

9. The method for preparing a composite material fan blade for an aero-engine according to claim 1, characterized in that: In step S5, a paste-like adhesive is used for bonding, and the curing after bonding is carried out by oven heating at a temperature of 70℃~90℃ for 1h~2h.

10. The method for preparing a composite material fan blade for an aero-engine according to claim 1, characterized in that: In step S6, the primer is an epoxy primer and the topcoat is a polyurethane topcoat. Both the primer and the topcoat are applied in 2 to 3 coats, and each coat is dried after application.

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