Co-curing preparation method of honeycomb sandwich composite material for airplane

Abstract

The invention relates to the technical field of sandwich composite materials, and particularly discloses a co-curing preparation method of a honeycomb sandwich composite material for an airplane, which comprises a lower mold, a prepreg laying layer, a honeycomb core body, an upper mold, an annular glue suction felt, a vacuum nozzle, a sealant and a vacuum bag, and further comprises the following steps: cleaning the molds by using a cleaning agent, wiping the contact surface of the mold and the sandwich plate to be dry to ensure that no obvious foreign matters exist on the surface; compared with traditional gluing forming, the upper die and the lower die are adopted for controlling the surface quality of the upper panel and the lower panel of the honeycomb sandwich composite material respectively, the technological process is simple, the production period is short, the gluing performance is better, compared with a traditional co-curing forming technology, the quality of the panel is higher, and the mechanical property of a formed component is better; the prepreg fibers can be prevented from buckling, so that the honeycomb sandwich composite material is more stable in quality and lower in rejection rate, and the preparation cost can be effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of sandwich composite materials, and in particular relates to a co-curing preparation method of a honeycomb sandwich composite material for aircraft. Background Art

[0002] Honeycomb sandwich structure composite materials have the advantages of light weight, high specific stiffness, high specific strength, strong designability, good energy absorption, etc. They are widely used in aerospace, transportation, and sports. In the aviation field, honeycomb sandwich composite materials are mainly used for secondary load-bearing components such as aircraft fuselage, wings, doors, bulkheads, and interiors. With their advantages of light weight and high strength, honeycomb sandwich composite materials can effectively reduce the weight of the aircraft, thereby improving flight efficiency and fuel economy. The core of the honeycomb structure plays a supporting role and provides excellent compressive resistance to ensure that the structure maintains stability and safety when it is subjected to aerodynamic loads and various mechanical loads during flight. At the same time, the core has excellent thermal insulation and sound insulation properties, which can effectively reduce noise and improve passenger comfort.

[0003] Honeycomb sandwich structure composite materials are generally composed of upper and lower panels, a honeycomb core and an adhesive between the panels and the core. The panels are usually made of metal materials or high-strength composite materials, and the core is usually made of lightweight materials such as aluminum alloy, aramid paper, and plastic. The panels provide most of the strength and rigidity for the structure, and the core improves the structure's energy absorption properties such as impact resistance and explosion resistance. The structural characteristics of honeycomb sandwich composite materials enable it to have higher strength performance while maintaining a lower density. It also has good corrosion resistance and fatigue resistance, can withstand complex working environments during its service life, and extend its service life.

[0004] The conventional preparation methods of honeycomb sandwich composite materials are adhesive bonding and co-curing. In adhesive bonding, the upper and lower panels are cured separately and bonded to the honeycomb structure with an adhesive. The adhesive bonding process has a long cycle and can effectively reduce the scrap rate. However, since the upper and lower panels have been pre-cured and have a large rigidity, they are prone to debonding due to mismatched surfaces during the secondary curing process with the honeycomb core. Therefore, the requirements for the contact surface between the upper and lower panels and the honeycomb core are high, and the number of curing molding times is large, which requires a long production cycle.

[0005] Co-curing molding is to lay up the upper and lower panels of the honeycomb sandwich composite material with prepreg and then cure them together with the honeycomb core. The upper and lower panels of the honeycomb sandwich composite material obtained by the co-curing molding process have better adhesion to the honeycomb core, but the mechanical properties of the panels are lower than those of the adhesive molding process. This is mainly due to the presence of the honeycomb core. During the curing process, the pressure on the panels is uneven, and the prepreg fibers buckle, resulting in a decrease in their mechanical properties.

[0006] In addition, the traditional honeycomb sandwich composite material bonding molding process requires the upper and lower panels to be cured separately, the molding process steps are relatively large, the molding process is cumbersome, the molding cycle is long, and the equipment use cost is high. Especially in the production process of honeycomb sandwich composite materials, since the bonding panel and the honeycomb core are only bonded by the adhesive in line contact, the bonding strength is greatly limited. The connection between the panel and the honeycomb core mainly depends on the adhesion of the adhesive, but this line contact cannot provide sufficient structural support. In practical applications, honeycomb sandwich composite materials are often faced with the situation of bearing uneven loads, especially under the action of concentrated force or impact load. The structure must not only resist the static pressure outside the plane, but also needs to withstand the shear force outside the plane. During the molding process, due to insufficient bonding strength, debonding between the panel and the honeycomb core is likely to occur, which in turn leads to failure of the entire structure. For this reason, a co-curing preparation method for honeycomb sandwich composite materials for aircraft is proposed.

[0007] Compared with traditional adhesive bonding molding, the present invention proposes a co-curing preparation method for honeycomb sandwich composite materials for aircraft. The surface quality of the upper and lower panels of the honeycomb sandwich composite materials is controlled by using upper and lower molds respectively. The process flow is simple, the production cycle is short, the adhesive performance is better, and the panel quality is higher than that of the traditional co-curing molding process, and the mechanical properties of the molded components are better. At the same time, during the pressurized curing process, the pressure applied by the upper and lower molds to the upper and lower panels respectively is more uniform than that directly pressurized by vacuum bags, which can prevent the prepreg fibers from buckling. The curing method of pressurizing the upper and lower molds makes the quality of the honeycomb sandwich composite materials more stable, the scrap rate is lower, and the preparation cost can be effectively reduced.

[0008] The co-curing molding method proposed in the present invention can effectively improve the connection quality between the panel and the honeycomb core, greatly shorten the production cycle, and during the heating and curing process, the resin will flow, and part of the resin will flow to the bonding position and then adhere to the honeycomb wall, thereby enhancing the bonding force between the honeycomb core and the panel, making the structure more stable.

[0009] The co-curing molding process of the honeycomb sandwich composite material of the present invention solves the problem that the quality of the upper panel is difficult to control during the co-curing process. Through reasonable mold design, the upper surface of the composite sandwich panel can be subjected to uniform pressure distribution during the curing process, avoiding the common panel deformation and uneven stress phenomena in traditional methods, not only effectively reducing the probability of buckling during fiber curing, but also improving the mechanical properties and surface quality of the upper panel. During the curing process, adhesive absorption felt is laid around the sandwich panel to absorb excess resin to prevent resin precipitation and contamination of the curing surface, thereby reducing the weight of the honeycomb sandwich composite material and ensuring the stability of the surface quality of the composite material.

[0010] The co-curing preparation method proposed in the present invention has significant advantages in improving the mechanical properties, surface quality and production efficiency of honeycomb sandwich composite materials. By simplifying the curing process, the complex steps in the traditional bonding process are reduced and the overall performance of the material is effectively improved. The co-curing preparation method proposed in the present invention has strong engineering practicality and is suitable for the preparation of components in the aerospace field. Summary of the invention

[0011] The purpose of the present invention is to provide a co-curing preparation method for honeycomb sandwich composite materials for aircraft, so as to solve the problem that the upper and lower panels of the honeycomb sandwich composite materials obtained by the co-curing molding process have better adhesion to the honeycomb core, but the mechanical properties of the panels are lower than those of the adhesive molding process. This is mainly due to the presence of the honeycomb core. During the curing process, the pressure on the panels is uneven, and the prepreg fibers are bent, resulting in a decrease in their mechanical properties.

[0012] To achieve the above object, the present invention provides the following technical solutions:

[0013] A co-curing preparation method of a honeycomb sandwich composite material for an aircraft, comprising a lower mold, a prepreg layer, a honeycomb core, an upper mold, an annular adhesive suction felt, a vacuum nozzle, a sealant and a vacuum bag, and also comprising:

[0014] S1: Use a cleaning agent to clean the mold, wipe the contact surface between the mold and the sandwich panel dry, and ensure that there is no obvious foreign matter on the surface;

[0015] S2: Spray the release agent on the molds respectively and wipe them with non-woven fabric to ensure that the release agent is evenly attached to the molds;

[0016] S3: Cut the non-porous isolation film and lay it on the lower mold to ensure that it is laid flat and has no obvious wrinkles;

[0017] S4: cutting the release cloth and laying the release cloth on the non-porous isolation film;

[0018] S5: Use carbon fiber unidirectional prepreg to lay the lower panel of the honeycomb sandwich composite material on the release cloth, and use a scraper to scrape each layer of prepreg flat to ensure that the prepreg layers are completely fitted together;

[0019] S6: Laying a release cloth on another lower mold, and laying the release cloth on the mold;

[0020] S7: Use carbon fiber unidirectional prepreg to lay the upper panel of the honeycomb sandwich composite material on the release cloth, and use a scraper to scrape each layer of prepreg flat to ensure that the prepreg layers are completely bonded;

[0021] S8: Spread high temperature epoxy resin on the two prepreg plies that have been laid up respectively;

[0022] S9: placing the honeycomb core on the prepreg ply to be used as the lower panel of the honeycomb sandwich composite material, peeling off the prepreg ply to be used as the upper panel of the honeycomb sandwich composite material from the lower mold, and placing it on the honeycomb core, with the surface on which the high-temperature epoxy resin is applied in contact with the honeycomb core;

[0023] S10: Cut the perforated isolation film to a size that ensures that it can completely cover the honeycomb sandwich composite material to be cured after being folded downward;

[0024] S11: laying a porous insulation film on a prepreg layer to be used as an upper panel of a honeycomb sandwich composite material, and folding four sides of the porous insulation film to wrap around the honeycomb sandwich composite material to be cured;

[0025] S12: placing the upper mold on the porous isolation membrane, the upper mold is located in the middle of the assembled honeycomb sandwich composite material, and the surface in contact with the porous isolation membrane is the surface sprayed with the release agent;

[0026] S13: Lay adhesive felt around the honeycomb sandwich composite material, and the distance between the adhesive felt and the honeycomb sandwich composite material is appropriate to ensure that the adhesive felt can smoothly absorb the precipitated resin and does not stick to the honeycomb sandwich composite material after curing;

[0027] S14: Vacuum nozzles are respectively arranged on both sides of the honeycomb sandwich composite material in the width direction;

[0028] S15: Spreading sealant around the lower mold;

[0029] S16: Bond the vacuum bag to the sealant, and press the vacuum bag and the sealant to bond them firmly;

[0030] S17: Evacuate the mold assembly and test its vacuum degree using a vacuum gauge;

[0031] S18: If the vacuum degree cannot meet the preparation requirements, check the leakage position of the mold clamping component;

[0032] S19: If the leakage is small, fill it with a proper amount of sealant and perform the vacuum test again until the vacuum meets the preparation requirements;

[0033] S20: When the air leakage is too large to be filled, the vacuum bag and sealant should be torn off, the mold should be cleaned again, and the sealant and the bonding vacuum bag should be laid, and the vacuum degree test should be carried out until the vacuum degree meets the preparation requirements, that is, the processes S16, S17, and S18 are repeated;

[0034] S21: sending the mold assembly with qualified vacuum degree into the autoclave;

[0035] S22: After the curing is completed, the mold assembly is naturally cooled at room temperature and demolded;

[0036] S23: Perform cutting and other machining operations on the cured honeycomb sandwich composite material to complete component preparation.

[0037] Preferably, the size of the release cloth cut is larger than the preset prepreg layer, and the size of the release cloth is smaller than the size of the non-porous isolation membrane.

[0038] Preferably, the size of the demoulding cloth laid on the lower mold is larger than the preset prepreg layer.

[0039] Preferably, the length direction of the upper mold is parallel to the 90° laying direction of the prepreg.

[0040] Preferably, the vacuum nozzle is located in the middle of the sandwich panel in the length direction and is symmetrical with the width direction of the lower mold.

[0041] Preferably, the vacuum degree of the mold clamping assembly is greater than or equal to 82%.

[0042] Preferably, the curing pressure of the autoclave is set to 2 bar, the curing temperature of the autoclave is set to 125° C., and the temperature is increased and kept warm for 1.5 hours according to the process curve required by the resin material.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] Compared with traditional adhesive bonding molding, the present invention proposes a co-curing preparation method for honeycomb sandwich composite materials for aircraft. The surface quality of the upper and lower panels of the honeycomb sandwich composite materials is controlled by using upper and lower molds respectively. The process flow is simple, the production cycle is short, the adhesive performance is better, and the panel quality is higher than that of the traditional co-curing molding process, and the mechanical properties of the molded components are better. At the same time, during the pressurized curing process, the pressure applied by the upper and lower molds to the upper and lower panels respectively is more uniform than that directly pressurized by vacuum bags, which can prevent the prepreg fibers from buckling. The curing method of pressurizing the upper and lower molds makes the quality of the honeycomb sandwich composite materials more stable, the scrap rate is lower, and the preparation cost can be effectively reduced.

[0045] The co-curing molding method proposed in the present invention can effectively improve the connection quality between the panel and the honeycomb core, greatly shorten the production cycle, and during the heating and curing process, the resin will flow, and part of the resin will flow to the bonding position and then adhere to the honeycomb wall, thereby enhancing the bonding force between the honeycomb core and the panel, making the structure more stable.

[0046] The co-curing molding process of the honeycomb sandwich composite material of the present invention solves the problem that the quality of the upper panel is difficult to control during the co-curing process. Through reasonable mold design, the upper surface of the composite sandwich panel can be subjected to uniform pressure distribution during the curing process, avoiding the common panel deformation and uneven stress phenomena in traditional methods, not only effectively reducing the probability of buckling during fiber curing, but also improving the mechanical properties and surface quality of the upper panel. During the curing process, adhesive absorption felt is laid around the sandwich panel to absorb excess resin to prevent resin precipitation and contamination of the curing surface, thereby reducing the weight of the honeycomb sandwich composite material and ensuring the stability of the surface quality of the composite material.

[0047] The co-curing preparation method proposed in the present invention has significant advantages in improving the mechanical properties, surface quality and production efficiency of honeycomb sandwich composite materials. By simplifying the curing process, the complex steps in the traditional bonding process are reduced and the overall performance of the material is effectively improved. The co-curing preparation method proposed in the present invention has strong engineering practicality and is suitable for the preparation of components in the aerospace field.

[0048] The quenched tempered glass mold controls the upper and lower surface qualities of the honeycomb sandwich composite material. The traditional process uses a vacuum bag to directly draw vacuum and pressurize, which cannot guarantee the upper surface quality of the honeycomb sandwich composite material. The patent of the present invention sprays a release agent on the upper mold, which directly contacts and pressurizes the upper surface of the honeycomb sandwich composite material, effectively ensuring the surface quality of the upper surface after curing.

[0049] The annular adhesive absorption felt is used to absorb the resin precipitated from the sandwich structure during the heating and curing process, which effectively reduces the weight of the product after curing and improves its specific stiffness and specific strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a structural diagram of the preparation process of the present invention;

[0051] Figure 2 It is a structural diagram of the clamping assembly of the present invention;

[0052] Figure 3 It is a structural diagram of the quenched and tempered glass mold of the present invention;

[0053] Figure 4 It is a structural diagram of the annular adhesive suction felt of the present invention;

[0054] Figure 5 It is a structural diagram of the present invention;

[0055] Figure 6 This is a three-dimensional structural diagram of the test piece prepared by the present invention.

[0056] In the figure: 1. lower mold; 2. support plate; 3. honeycomb core; 4. upper mold; 5. annular adhesive suction felt; 6. vacuum nozzle; 7. sealant; 8. vacuum bag. DETAILED DESCRIPTION

[0057] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0058] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 As shown, a co-curing preparation method of a honeycomb sandwich composite material for aircraft includes a lower mold 1, a prepreg layer 2, a honeycomb core 3, an upper mold 4, an annular adhesive suction felt 5, a vacuum nozzle 6, a sealant 7 and a vacuum bag 8, and also includes:

[0059] S1: Use a cleaning agent to clean the mold, wipe the contact surface between the mold and the sandwich panel dry, and ensure that there is no obvious foreign matter on the surface;

[0060] S2: Spray the release agent on the molds respectively and wipe them with non-woven fabric to ensure that the release agent is evenly attached to the molds;

[0061] S3: Cut the non-porous isolation film to a size slightly larger than the preset prepreg layer, and lay the non-porous isolation film on the lower mold 1 to ensure that it is laid flat and has no obvious wrinkles;

[0062] S4: cutting a release cloth to a size slightly larger than the preset prepreg layer and slightly smaller than the size of the non-porous isolation film, and laying the release cloth on the non-porous isolation film;

[0063] S5: Use carbon fiber unidirectional prepreg to lay the lower panel of the honeycomb sandwich composite material on the release cloth. The laying should be carried out according to the design requirements. Use a scraper to scrape each layer of prepreg flat to ensure that the prepreg layers are completely fitted together.

[0064] S6: Laying a release cloth on another lower mold 1, wherein the cut release cloth is slightly larger than the preset prepreg layer, and laying the release cloth on the mold;

[0065] S7: Use carbon fiber unidirectional prepreg to lay the upper panel of honeycomb sandwich composite material on the release cloth. The laying should be carried out according to the design requirements. Use a scraper to scrape each layer of prepreg flat to ensure that the prepreg layers are completely bonded to each other.

[0066] S8: Spread high-temperature epoxy resin on two prepreg layers that have been stacked. Epoxy resin A and B should be mixed strictly according to the ratio requirements and spread in the same direction to ensure that the resin is spread evenly. The amount of high-temperature epoxy resin spread should be appropriate, so that there is no obvious flow of resin on the prepreg layer after spreading.

[0067] S9: placing the honeycomb core on the prepreg ply to be used as the lower panel of the honeycomb sandwich composite material, peeling off the prepreg ply to be used as the upper panel of the honeycomb sandwich composite material from the lower mold 1, and placing it on the honeycomb core, with the surface of the prepreg ply brushed with high temperature epoxy resin in contact with the honeycomb core;

[0068] S10: Cut the perforated isolation film to a size that ensures that it can completely cover the honeycomb sandwich composite material to be cured after being folded downward;

[0069] S11: laying a porous insulation film on a prepreg layer to be used as an upper panel of a honeycomb sandwich composite material, and folding four sides of the porous insulation film to wrap around the honeycomb sandwich composite material to be cured;

[0070] S12: placing the upper mold on the porous isolation membrane, the upper mold is located in the middle of the assembled honeycomb sandwich composite material, the surface in contact with the porous isolation membrane is the surface sprayed with the release agent, and the length direction of the upper mold 4 should be parallel to the 90° laying direction of the prepreg;

[0071] S13: Lay adhesive felt around the honeycomb sandwich composite material, and the distance between the adhesive felt and the honeycomb sandwich composite material is appropriate to ensure that the adhesive felt can smoothly absorb the precipitated resin and does not stick to the honeycomb sandwich composite material after curing;

[0072] S14: Vacuum nozzles 6 are respectively arranged on both sides of the honeycomb sandwich composite material in the width direction, ensuring that the vacuum nozzles 6 are located in the middle of the sandwich panel in the length direction and are symmetrical in the width direction;

[0073] S15: Laying the sealant 7 around the lower mold 1, paying attention to the laying condition at the corners, and appropriately increasing the amount of the sealant 7 at the corners;

[0074] S16: Bond the vacuum bag 8 to the sealant 7, press the vacuum bag 8 and the sealant 7 to bond them firmly, and try not to generate wrinkles during bonding. If wrinkles occur, add more sealant 7 at the wrinkles to ensure good overall air tightness after bonding;

[0075] S17: Evacuate the mold assembly and test its vacuum degree using a vacuum gauge. If the vacuum degree is greater than or equal to 82%, it means that the vacuum degree is good and meets the preparation requirements.

[0076] S18: If the vacuum degree cannot meet the preparation requirements, check the leakage position of the mold clamping component;

[0077] S19: If the air leakage is small, fill it with a proper amount of sealant 7 and perform the vacuum test again until the vacuum meets the preparation requirements;

[0078] S20: When the air leakage is too large to be filled, the vacuum bag 8 and the sealant 7 should be torn off, the lower mold should be cleaned again, the sealant 7 and the bonding vacuum bag 8 should be laid, and the vacuum degree test should be carried out until the vacuum degree meets the preparation requirements, that is, the processes S16, S17, and S18 are repeated;

[0079] S21: Send the mold assembly with qualified vacuum degree into the autoclave, set the curing pressure to 2 bar, set the curing temperature to 125°C, and heat up and keep warm for 1.5 hours according to the process curve required by the resin material;

[0080] S22: After the curing is completed, the mold assembly is naturally cooled at room temperature and demolded;

[0081] S23: Perform cutting and other machining operations on the cured honeycomb sandwich composite material to complete component preparation.

[0082] As can be seen from the above, first clean the lower mold 1 and the upper mold 4 to ensure that there is no dust and foreign matter on the surface, then spray the release agent and wipe it with a non-woven cloth to ensure that the release agent is evenly attached, lay the carbon fiber unidirectional prepreg on the lower mold 1 to avoid bubbles and separation, use a scraper to flatten each layer of prepreg to ensure that the layers are completely fitted, and set the layer in the center of the mold;

[0083] Evenly apply high-temperature epoxy resin on the prepreg layer, mix them strictly according to the ratio of A and B agents, and spread them in the same direction. After the laying is completed, the honeycomb core 3 is placed in the center of the prepreg layer to ensure that the resin surface is in contact with the honeycomb core. Then, the upper mold 4 is placed on the layer, and the honeycomb sandwich composite material is surrounded by an annular adhesive felt 5 to ensure that the adhesive felt is not in contact with the honeycomb sandwich composite material and can smoothly absorb the resin precipitated during the curing process;

[0084] Two vacuum nozzles 6 are set on the lower mold 1 to ensure that the upper mold can apply pressure evenly after vacuuming. Then, sealant 7 is applied around the mold to ensure continuous sealing without gaps. After that, the vacuum bag 8 is bonded to the sealant and pressed to fix it to avoid wrinkles. If there are wrinkles, sealant should be added at the wrinkles to complete the airtightness test to ensure that the vacuum degree is stable after vacuuming and there is no leakage.

[0085] After the air tightness is qualified, the component is sent to the autoclave, the pressure is set to 2 bar, the curing temperature is 125 ° C, and the temperature is increased and kept warm for 1.5 hours according to the process curve. After the curing is completed, the component is naturally cooled and demoulded, and finally cut and machined to complete the preparation of the honeycomb sandwich composite material. The prepared honeycomb sandwich composite material is as follows Figure 6 shown.

[0086] Through the setting of the above technical scheme, compared with the traditional adhesive forming, the present invention proposes a co-curing preparation method for honeycomb sandwich composite materials for aircraft, which adopts upper and lower molds to respectively control the surface quality of the upper and lower panels of the honeycomb sandwich composite materials, has a simple process flow, a short production cycle, and better adhesive performance, and has higher panel quality and better mechanical properties of the molded components than the traditional co-curing forming process. At the same time, during the pressurized curing process, the pressure applied by the upper and lower molds to the upper and lower panels is more uniform than that directly pressurized by vacuum bags, which can prevent the prepreg fibers from buckling. The curing method of pressurizing the upper and lower molds makes the quality of the honeycomb sandwich composite materials more stable, the scrap rate is lower, and the preparation cost can be effectively reduced.

[0087] The co-curing molding method proposed in the present invention can effectively improve the connection quality between the panel and the honeycomb core, greatly shorten the production cycle, and during the heating and curing process, the resin will flow, and part of the resin will flow to the bonding position and then adhere to the honeycomb wall, thereby enhancing the bonding force between the honeycomb core and the panel, making the structure more stable.

[0088] The co-curing molding process of the honeycomb sandwich composite material of the present invention solves the problem that the quality of the upper panel is difficult to control during the co-curing process. Through reasonable mold design, the upper surface of the composite sandwich panel can be subjected to uniform pressure distribution during the curing process, avoiding the common panel deformation and uneven stress phenomena in traditional methods, not only effectively reducing the probability of buckling during fiber curing, but also improving the mechanical properties and surface quality of the upper panel. During the curing process, adhesive absorption felt is laid around the sandwich panel to absorb excess resin to prevent resin precipitation and contamination of the curing surface, thereby reducing the weight of the honeycomb sandwich composite material and ensuring the stability of the surface quality of the composite material.

[0089] The co-curing preparation method proposed in the present invention has significant advantages in improving the mechanical properties, surface quality and production efficiency of honeycomb sandwich composite materials. By simplifying the curing process, the complex steps in the traditional bonding process are reduced and the overall performance of the material is effectively improved. The co-curing preparation method proposed in the present invention has strong engineering practicality and is suitable for the preparation of components in the aerospace field.

[0090] The quenched tempered glass mold controls the upper and lower surface qualities of the honeycomb sandwich composite material. The traditional process uses a vacuum bag to directly draw vacuum and pressurize, which cannot guarantee the upper surface quality of the honeycomb sandwich composite material. The patent of the present invention sprays a release agent on the upper mold, which directly contacts and pressurizes the upper surface of the honeycomb sandwich composite material, effectively ensuring the surface quality of the upper surface after curing.

[0091] The annular adhesive absorption felt is used to absorb the resin precipitated from the sandwich structure during the heating and curing process, which effectively reduces the weight of the product after curing and improves its specific stiffness and specific strength.

[0092] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A co-curing preparation method for honeycomb sandwich composite materials for aircraft, characterized in that: The invention comprises a lower mold (1), a prepreg layer (2), a honeycomb core (3), an upper mold (4), an annular adhesive suction felt (5), a vacuum nozzle (6), a sealant (7) and a vacuum bag (8), and also comprises: S1: Use a cleaning agent to clean the mold, wipe the contact surface between the mold and the sandwich panel dry, and ensure that there is no obvious foreign matter on the surface; S2: Spray the release agent on the molds respectively and wipe them with non-woven fabric to ensure that the release agent is evenly attached to the molds; S3: cutting the non-porous isolation film and laying the non-porous isolation film on the lower mold (1), ensuring that the non-porous isolation film is laid flat and has no obvious wrinkles; S4: cutting the release cloth and laying the release cloth on the non-porous isolation film; S5: Use carbon fiber unidirectional prepreg to lay the lower panel of the honeycomb sandwich composite material on the release cloth, and use a scraper to scrape each layer of prepreg flat to ensure that the prepreg layers are completely fitted together; S6: Laying a release cloth on another lower mold 1, and laying the release cloth on the mold; S7: Use carbon fiber unidirectional prepreg to lay the upper panel of the honeycomb sandwich composite material on the release cloth, and use a scraper to scrape each layer of prepreg flat to ensure that the prepreg layers are completely bonded; S8: Spread high temperature epoxy resin on the two prepreg plies that have been laid up respectively; S9: placing the honeycomb core on the prepreg ply intended to be the lower panel of the honeycomb sandwich composite material, peeling off the prepreg ply intended to be the upper panel of the honeycomb sandwich composite material from the lower mold (1), and placing it on the honeycomb core, with the surface of the prepreg ply applied with the high temperature epoxy resin in contact with the honeycomb core; S10: Cut the perforated isolation film to a size that ensures that it can completely cover the honeycomb sandwich composite material to be cured after being folded downward; S11: laying a porous insulation film on a prepreg layer to be used as an upper panel of a honeycomb sandwich composite material, and folding four sides of the porous insulation film to wrap around the honeycomb sandwich composite material to be cured; S12: placing the upper mold on the porous isolation membrane, the upper mold is located in the middle of the assembled honeycomb sandwich composite material, and the surface in contact with the porous isolation membrane is the surface sprayed with the release agent; S13: Lay adhesive felt around the honeycomb sandwich composite material, and the distance between the adhesive felt and the honeycomb sandwich composite material is appropriate to ensure that the adhesive felt can smoothly absorb the precipitated resin and does not stick to the honeycomb sandwich composite material after curing; S14: Vacuum nozzles (6) are respectively arranged on both sides of the honeycomb sandwich composite material in the width direction; S15: Laying a sealant (7) around the lower mold (1); S16: bonding the vacuum bag (8) to the sealant (7), and pressing the vacuum bag (8) and the sealant (7) to firmly bond them; S17: Evacuate the mold assembly and test its vacuum degree using a vacuum gauge; S18: If the vacuum degree cannot meet the preparation requirements, check the leakage position of the mold clamping component; S19: If the air leakage is small, fill it with a proper amount of sealant (7) and perform a vacuum test again until the vacuum meets the preparation requirements; S20: When the air leakage is too large to be filled, the vacuum bag (8) and the sealant (7) should be torn off, the mold should be cleaned again, the sealant (7) and the vacuum bag (8) should be laid, and the vacuum degree test should be carried out until the vacuum degree meets the preparation requirements, that is, the processes S16, S17, and S18 are repeated; S21: sending the mold assembly with qualified vacuum degree into the autoclave; S22: After the curing is completed, the mold assembly is naturally cooled at room temperature and demolded; S23: Perform cutting and other machining operations on the cured honeycomb sandwich composite material to complete component preparation.

2. The co-curing preparation method of a honeycomb sandwich composite material for aircraft according to claim 1, characterized in that: The cut size of the release cloth is larger than the preset prepreg layer, and the size of the release cloth is smaller than the size of the non-porous isolation film.

3. The co-curing preparation method of a honeycomb sandwich composite material for aircraft according to claim 1, characterized in that: The size of the demoulding cloth laid on the lower mold (1) is larger than the preset prepreg layer.

4. The co-curing preparation method of a honeycomb sandwich composite material for aircraft according to claim 1, characterized in that: The length direction of the upper mold (4) is parallel to the 90° laying direction of the prepreg.

5. The co-curing preparation method of a honeycomb sandwich composite material for aircraft according to claim 1, characterized in that: The vacuum nozzle (6) is located in the middle of the sandwich panel in the length direction and is symmetrical with the width direction of the lower mold (1).

6. The co-curing preparation method of a honeycomb sandwich composite material for aircraft according to claim 1, characterized in that: The vacuum degree of the mold clamping component is greater than or equal to 82%.

7. The co-curing preparation method of a honeycomb sandwich composite material for aircraft according to claim 1, characterized in that: The curing pressure of the autoclave is set to 2 bar, the curing temperature of the autoclave is set to 125° C., and the temperature is increased and kept warm for 1.5 hours according to the process curve required by the resin material.

Images