Vacuum sealing method for high-temperature forming of composite autoclave

Abstract

The invention discloses a vacuum sealing method for high-temperature forming of a composite autoclave. The technical problem that a vacuum bag is prone to deformation at high temperature in the prior art is solved. The vacuum sealing method for high-temperature forming of the composite autoclave mainly comprises the steps of assembling of a forming mold, laying of prepreg, vacuum coating of the mold, curing of the autoclave and demolding. The vacuum bag used for wrapping the mold is made of aluminum foil or glass fiber reinforced aluminum foil. The plastic film has good ductility, electrical conductivity, thermal conductivity and shading performance, and can effectively block oxygen, moisture and peculiar smell. The problem of vacuum leakage in the curing process of polyimide and other high-temperature-resistant materials is effectively solved, and a reliable vacuum auxiliary material is provided for molding of products with high temperature resistance level and certain functionality. The method not only improves the forming quality of the composite material, but also reduces the production cost, and has remarkable economic benefits and social benefits.

Description

Technical Field

[0001] The present application belongs to the technical field of hot pressing molding, and specifically relates to a high-temperature molding vacuum sealing method for a composite material hot pressing tank. Background Art

[0002] In order to meet the high temperature, high strength and high toughness requirements of composite materials for aerospace vehicles, lightweight and high mobility, the temperature level in the application area of ​​structural composite materials is getting higher and higher, reaching above 300°C. Conventional composite material systems based on epoxy resin, bismaleimide resin, etc. cannot meet the requirements of the use environment.

[0003] Polyimide resin has excellent high temperature resistance, and its fiber-reinforced composite materials can be used for a long time at 300°C, which can meet the requirements of the product working environment. However, the curing process of polyimide composite materials requires high temperature and high pressure, and has high requirements for vacuum auxiliary materials.

[0004] The existing nylon vacuum bags have poor sealing quality stability when the curing temperature is above 250°C. At high temperatures, they are prone to deformation and damage, leading to vacuum leakage, which in turn increases the internal porosity of resin-based composite products, thereby affecting the mechanical properties of the composite materials and causing the products to be scrapped. Summary of the invention

[0005] In order to solve the above technical problems, the present application provides a composite material autoclave high temperature molding vacuum sealing method.

[0006] The technical solution adopted to achieve the purpose of this application is that the present invention discloses a composite material autoclave high temperature molding vacuum sealing method, comprising the following steps:

[0007] Place the product into the mold;

[0008] According to the size of the mold, cut a vacuum bag of appropriate size, flatten the vacuum bag, place a layer of polytetrafluoroethylene cloth or glass fiber cloth on the inner surface of the vacuum bag, and then place the mold in the vacuum bag;

[0009] Laying a layer of breathable material on the mold, folding the vacuum bag to wrap the mold, reserving a hole according to the size of the vacuum nozzle, installing the vacuum nozzle and sealing it with a silicone rubber sheet, tightening the vacuum nozzle, and sealing the vacuum bag;

[0010] The vacuum bag is evacuated, and when the vacuum value in the vacuum bag reaches a first preset value, the vacuum system is turned off to ensure that the decrease in the vacuum value in the vacuum bag within a predetermined time is less than a second preset value;

[0011] Carry out autoclave curing and cooling after curing;

[0012] After the mold is cooled, the vacuum bag is removed and demoulding is performed to take out the product;

[0013] The vacuum bag material is aluminum foil or glass fiber reinforced aluminum foil.

[0014] In some embodiments, the aluminum foil or glass fiber reinforced aluminum foil has a thickness of 0.2-0.5 mm.

[0015] In some embodiments, before placing the product into the mold, the prepreg is first cut into corresponding sizes, and the prepreg is laid layer by layer in the mold cavity according to the laying order. Each time a layer of the prepreg is laid, a polytetrafluoroethylene strip is used to drive out air, press and compact it. This operation is repeated until all the designed number of prepreg layers are laid.

[0016] In some embodiments, before the vacuum bag is wrapped outside the mold, the screw holes on the surface of the mold are first filled.

[0017] In some embodiments, when the vacuum bag is wrapped around the mold, the breathable material is polytetrafluoroethylene cloth or glass fiber cloth.

[0018] In some embodiments, the vacuum bag is sealed by folding the four sides of the vacuum bag so that the edges of the vacuum bag are folded multiple times and then clamping with a bow clamp.

[0019] In some embodiments, during the autoclave curing process, a vacuum state is maintained, and pressurization and multiple heating, heat preservation, and exhaust operations are performed, and the temperature is controlled at 225-320°C.

[0020] In some embodiments, during the autoclave curing process, when the temperature reaches 280° C., the pressurization process is performed until the pressure reaches 3 MPa, and when the temperature reaches 320° C., the curing begins.

[0021] In some embodiments, after the mold is cooled to below 60° C., the autoclave is opened, the vacuum bag is removed and demolding is performed.

[0022] In some embodiments, the stop bar is selected according to the thickness of the pressing test plate, the tooling is cleaned with anhydrous ethanol, and the punch, die and stop bar of the mold are treated with a high-temperature release agent twice.

[0023] The composite material autoclave high temperature molding vacuum sealing method disclosed in the present application comprises the following steps: placing the product in a mold. According to the size of the mold, cutting a vacuum bag of suitable size, flattening the vacuum bag, placing a layer of polytetrafluoroethylene cloth or glass fiber cloth on the inner surface of the vacuum bag, and then placing the mold in the vacuum bag. Laying a layer of breathable material on the mold, folding the vacuum bag to wrap the mold, reserving holes according to the size of the vacuum nozzle, installing the vacuum nozzle and sealing it with a silicone rubber sheet, tightening the vacuum nozzle, and sealing the vacuum bag. The vacuum bag is evacuated, and the vacuum system is turned off when the vacuum value in the vacuum bag reaches a first preset value, ensuring that the vacuum value in the vacuum bag decreases less than a second preset value within a predetermined time. The autoclave is cured, and the curing is completed and cooled. After the mold is cooled, the vacuum bag is disassembled and demolded to take out the product. Wherein, the vacuum bag material is aluminum foil or glass fiber reinforced aluminum foil.

[0024] The composite material autoclave high temperature molding vacuum sealing method of the present invention effectively solves the problem of vacuum leakage during the curing process of high temperature resistant materials such as polyimide, and provides a reliable vacuum auxiliary material for the molding of products with high temperature resistance and certain functionality. The method not only improves the molding quality of the composite material, but also reduces the production cost, and has significant economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic flow chart of a composite material autoclave high temperature molding vacuum sealing method in an embodiment of the present application;

[0026] Figure 2 This is a schematic diagram of the assembly of the vacuum bag and the mold in the embodiment of the present application;

[0027] Figure 3 It is an enlarged schematic diagram of the assembly of the bow clamp and the vacuum bag in the embodiment of the present application.

[0028] Description of reference numerals:

[0029] 100-vacuum bag, 200-mold, 300-silicone rubber sheet, 400-vacuum nozzle, 500-bow clamp. DETAILED DESCRIPTION

[0030] In order to make the technical personnel in the technical field to which the present application belongs to understand the present application more clearly, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0031] In addition, the present application may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplicity and clarity, and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides various specific examples of processes and materials, but those of ordinary skill in the art may recognize the application of other processes and / or the use of other materials.

[0032] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0033] The embodiment of the invention discloses a composite material autoclave high temperature molding vacuum sealing method, which can solve the technical problem that vacuum bags are easily deformed at high temperatures, thereby improving the molding quality of composite materials.

[0034] The technical solution of the present application is described in detail below through specific embodiments:

[0035] See also Figure 1 , Figure 2 and Figure 3 , the present application discloses a composite material autoclave high temperature molding vacuum sealing method, which includes the following steps: placing a product in a mold 200. According to the size of the mold 200, cutting a vacuum bag 100 of a suitable size, flattening the vacuum bag 100, and placing a layer of polytetrafluoroethylene cloth or glass fiber cloth on the inner surface of the vacuum bag 100, and then placing the mold 200 in the vacuum bag 100. Laying a layer of breathable material on the mold 200, folding the vacuum bag 100 to wrap the mold 200, reserving holes according to the size of the vacuum nozzle 400, installing the vacuum nozzle 400 and using a silicone rubber sheet 300 for sealing, tightening the vacuum nozzle 400, and sealing the vacuum bag 100. Evacuating the vacuum bag 100, turning off the vacuum system when the vacuum value in the vacuum bag 100 reaches a first preset value, and ensuring that the decrease in the vacuum value in the vacuum bag 100 within a predetermined time is less than a second preset value. Perform autoclave curing, and cool after curing. After the mold 200 is cooled, the vacuum bag 100 is disassembled and demoulded to take out the product.

[0036] Among them, the material of the vacuum bag 100 is aluminum foil or glass fiber reinforced aluminum foil. Aluminum foil is a thin metal sheet with a thickness of 0.2mm to 0.5mm processed by an aluminum foil rolling mill. It has good ductility, electrical conductivity, thermal conductivity and light shielding properties, and can effectively block oxygen, moisture and odor. In the vacuum bag 100 film, aluminum foil plays a major barrier role and can protect the items in the package from the influence of the external environment. Glass fiber reinforced aluminum foil is a composite film material with excellent performance formed by combining glass fiber and aluminum foil through a specific process. This composite structure not only retains the barrier properties of aluminum foil, but also enhances the mechanical strength of the film material.

[0037] In one embodiment, the thickness of the aluminum foil or the glass fiber reinforced aluminum foil is 0.2-0.5 mm, which ensures both the barrier properties of the film and its stability and durability during the packaging process.

[0038] In one embodiment, before placing the product into the mold 200, the prepreg is cut into corresponding sizes, and the prepreg is laid layer by layer in the mold cavity of the mold 200 according to the laying order. Each time a layer of prepreg is laid, a polytetrafluoroethylene strip is used to drive out air, press and compact it, and this operation is repeated until all the designed prepreg layers are laid. This can avoid wrinkles, bulges or inclusions.

[0039] Prepreg is a composite reinforcement material that has been pre-impregnated with resin and partially cured. It usually includes glass fiber, carbon fiber or other reinforcing fibers. During the cutting process, the size must be accurate to avoid wasting materials or affecting subsequent layering. The layering sequence of the prepreg is determined according to the product design requirements and process specifications. The layering sequence usually includes factors such as fiber direction, number of layers, and interlayer interface treatment. The cut prepreg is laid layer by layer in the cavity of the mold 200 according to the layering sequence. During the laying process, the prepreg must be kept flat to avoid wrinkles or bubbles. After each layer of prepreg is laid, a polytetrafluoroethylene strip (or other suitable tools) is used to remove air from the prepreg and the cavity of the mold 200. At the same time, the prepreg must be pressed flat to ensure that it fits tightly with the cavity of the mold 200. During the layering process, special attention should be paid to the interface treatment between the layers to ensure that the layers can be tightly combined. During the layering process, the quality, size and layering sequence of the prepreg should be checked regularly to see if they meet the requirements. At the same time, the laying conditions of each layer must be recorded for subsequent quality control and problem tracing.

[0040] In one embodiment, before the vacuum bag 100 is wrapped outside the mold 200, the screw holes on the surface of the mold 200 are first filled. In the composite material molding process, ensuring the flatness and sealing of the mold 200 surface is crucial to the quality and performance of the final product. Therefore, before the vacuum bag 100 is wrapped outside the mold 200, it is an important step to fill the screw holes on the surface of the mold 200. The implementation of this step can avoid the vacuum bag 100 film located above the pores being depressed downward after being subjected to vacuum pressure during the vacuuming process, causing the vacuum bag 100 film to be damaged. If the screw holes on the surface of the mold 200 are not filled, the vacuum bag 100 may not be able to fit the surface of the mold 200 tightly when wrapped, resulting in gas leakage and affecting the vacuum effect. During the curing process of the composite material, the resin may leak out through the holes on the surface of the mold 200, which will not only waste materials, but also pollute the working environment and even affect the performance of the final product. Filling the screw holes on the surface of the mold 200 can ensure that the composite material is evenly distributed in the mold 200, avoid the formation of bubbles or voids during the curing process, and thus improve the quality and performance of the product.

[0041] Select appropriate filling materials, such as putty, sealant or special mold 200 filling agent. These materials should have good fluidity and curing properties, be able to fill holes and fit tightly to the surface of the mold 200. Apply the filling material evenly on the screw holes on the surface of the mold 200, and then scrape it flat with a scraper or scraper to ensure that the filling material is flat and consistent with the surface of the mold 200. According to the curing requirements of the filling material, carry out necessary curing treatment. This usually includes steps such as heating, drying or waiting for natural curing to ensure that the filling material is completely cured and firmly attached to the surface of the mold 200.

[0042] In one embodiment, when the vacuum bag 100 is wrapped in the mold 200, the breathable material is polytetrafluoroethylene cloth or glass fiber cloth. Breathable material refers to a material that allows gas (such as air) to pass through and may have other functions (such as waterproof, windproof, warm, etc.). According to its composition and application field, breathable materials can be divided into various types, such as polymer waterproof breathable materials (such as PTFE membranes), textile breathable materials (such as special woven fabrics), industrial breathable materials (such as EVA sponge tapes, aluminum foil tapes, etc.) and breathable material diaphragms (such as membrane filters, membrane separators, etc.).

[0043] Polytetrafluoroethylene has extremely high chemical stability and can withstand corrosion from a variety of chemicals, including strong acids, strong alkalis, and organic solvents. This enables PTFE cloth (polytetrafluoroethylene cloth) to effectively prevent resin or other chemicals from corroding the vacuum bag 100 during the composite material molding process. PTFE cloth has excellent high temperature resistance and can maintain stable physical and chemical properties in a high temperature environment. This is especially important for composite products that require high temperature curing. Although PTFE cloth is a polymer material, it still has a certain degree of air permeability. This air permeability helps to form a uniform pressure distribution in the vacuum bag 100, thereby ensuring that the composite material is fully compacted and cured in the mold 200. The surface of PTFE cloth is smooth and not easy to adhere to resin or other impurities, so it is easy to clean and maintain after use.

[0044] Both PTFE cloth and glass fiber cloth are excellent breathable materials, suitable for different composite material molding processes. When choosing, it is necessary to make comprehensive considerations based on the specific application scenarios and performance requirements.

[0045] In one embodiment, the vacuum bag 100 is sealed by folding the four sides of the vacuum bag 100, folding the edges of the vacuum bag 100 multiple times, and then clamping the vacuum bag 100 with a bow-shaped clamp 500. In the composite material molding or vacuum packaging process, ensuring the sealing of the vacuum bag 100 is very important to prevent gas leakage, ensure internal pressure stability, and protect the packaged objects. Folding the four sides of the vacuum bag 100 and clamping it with a bow-shaped clamp 500 is a simple and effective means to achieve sealing.

[0046] First, fold the four sides of the vacuum bag 100 inward to form a multi-layer folded edge. The number of folds can be determined according to actual needs and the thickness of the vacuum bag 100. It is generally recommended to fold at least two to three layers to ensure the firmness and reliability of the seal. During the folding process, ensure that each layer is closely aligned to avoid misalignment or wrinkles. At the same time, gently press the folded part with your hands or tools to make it flatter and facilitate subsequent clamping operations. Clamp the bow clamps 500 (also known as C-clamps or spring clamps) one by one along the folded edges of the vacuum bag 100. The design of the bow clamps 500 enables it to firmly clamp multiple layers of material while maintaining a certain degree of elasticity to accommodate the slight deformation that may occur in the vacuum bag 100 during the curing or packaging process. After clamping all the bow clamps 500, it is necessary to check the sealing of the vacuum bag 100. You can observe whether there is any sign of gas leakage by gently patting or squeezing the vacuum bag 100. If necessary, you can use a vacuum pump to perform an air extraction test on the vacuum bag 100 to ensure that it is completely sealed.

[0047] The size and material of the bow clamp 500 should be selected according to the thickness and size of the vacuum bag 100. Make sure that the selected bow clamp 500 can firmly clamp the edge of the folded vacuum bag 100 without causing damage to it. During the clamping process, make sure that the clamping force of the bow clamp 500 is evenly distributed on the entire edge of the vacuum bag 100. Avoid applying excessive clamping force in a certain part to avoid causing the vacuum bag 100 to rupture or deform. After clamping, it is necessary to check the tightness of each bow clamp 500. Make sure that they are all firmly fixed on the vacuum bag 100 without signs of looseness or falling off. Although folding can increase the firmness of the seal, excessive folding may cause the internal space of the vacuum bag 100 to be reduced, affecting the placement and curing effect of the packaging. Therefore, moderate control should be exercised according to actual conditions when folding.

[0048] In one embodiment, during the autoclave curing process, a vacuum state is maintained, and pressurization and multiple heating, insulation, and exhaust operations are performed, and the temperature is controlled at 225-320°C. During the autoclave curing process, it is crucial to maintain a vacuum state. This can not only effectively remove the air and volatiles inside the material, but also prevent external gases from interfering with the curing process. Usually, the gas in the vacuum bag 100 is extracted by a vacuum pump to maintain the required vacuum degree. Pressurization is another key step in the autoclave curing process. By applying a certain pressure, it can be ensured that the material fully fills the mold 200 to form a dense structure. At the same time, pressure can also affect the fluidity and molding speed of the material, thereby affecting the quality and performance of the product. Pressurization methods include mechanical pressurization, hydraulic pressurization, and pneumatic pressurization, and the specific selection should be considered comprehensively based on actual production needs and economic factors.

[0049] The purpose of heating is to make the material reach the required curing temperature. During the heating process, the heating rate needs to be strictly controlled to avoid internal stress or deformation of the material due to too rapid temperature change. The insulation stage is to keep the material at the required temperature for a period of time to ensure that it is fully cured. The length of the insulation time depends on the type and thickness of the material and the required degree of curing. Temperature control in the range of 225-320°C is an important parameter in the autoclave curing process. The choice of temperature should be determined according to the type of material, curing characteristics and required performance requirements. For example, for some resin systems, higher curing temperatures can increase the crosslinking density and mechanical properties of the material, but may also cause excessive degradation or deformation of the material. Therefore, in actual operation, it is necessary to consider various factors comprehensively and select the appropriate curing temperature.

[0050] At the same time, the autoclave should be equipped with a precise temperature control system to ensure the accuracy and stability of the heating temperature. The temperature control system should be able to monitor and adjust the temperature inside the tank in real time and automatically adjust according to the set temperature curve.

[0051] In one embodiment, during the autoclave curing process, when the temperature reaches 280°C, pressurization is performed until the pressure reaches 3MPa, and when the temperature reaches 320°C, curing begins. When the temperature reaches 280°C, pressurization is performed. The purpose of this step is to ensure that the material can be fully compacted during the curing process, and the internal bubbles and volatiles are removed to obtain a dense cured structure. The pressurized pressure should reach 3MPa, and this pressure value can be adjusted according to the specific material properties and curing requirements. During the pressurization process, it is necessary to pay close attention to the reaction of the material to avoid material damage caused by excessive pressure. When the temperature reaches 320°C, curing begins. Curing is a key step in the autoclave process, which determines the final performance of the composite material. During the curing process, the resin inside the material will undergo a cross-linking reaction to form a stable network structure. The choice of curing temperature and time should be determined according to the type of material, thickness and required performance requirements.

[0052] 320℃ is a relatively high curing temperature, which is suitable for some composite materials that require high temperature curing. At high temperatures, the cross-linking reaction of the resin will be accelerated, which is conducive to shortening the curing time. However, it should be noted that too high a temperature may also cause the material to decompose or produce other adverse reactions. The length of the curing time depends on the type and thickness of the material and the curing temperature. At 320℃, the curing time usually takes several hours or even longer. During the curing process, the temperature needs to be kept stable and uniform to ensure that the material can be fully cured.

[0053] In one embodiment, after the mold 200 is cooled to below 60°C, the autoclave is opened, the vacuum bag 100 is removed and demolding is performed. After the autoclave curing treatment of the fuel cell or other composite product is completed, when the mold 200 is cooled to below 60°C, it is a safe and appropriate time to perform subsequent operations (such as opening the autoclave, removing the vacuum bag 100 and demolding). 60°C is generally regarded as a safe operating temperature because at this temperature, the thermal stress of the material is small and it is not easy to deform or crack due to sudden temperature changes. The length of the cooling time depends on the type of material, thickness and heat capacity after curing. Generally speaking, thicker products and materials with high heat capacity require longer cooling times.

[0054] In one embodiment, the stop bar is selected according to the thickness of the pressed test plate, the tooling is cleaned with anhydrous ethanol, and the convex mold, concave mold and stop bar of the mold 200 are treated with a high-temperature release agent twice. The tooling may be exposed to various impurities, oil stains, etc. during the assembly and use of the mold 200. Cleaning with anhydrous ethanol can remove these impurities and oil stains and ensure the cleanliness of the tooling surface. Clean tooling can improve the assembly accuracy and service life of the mold 200, and also help improve the quality of the test plate.

[0055] The high temperature release agent is a chemical substance specially used for demolding the mold 200, which can reduce the adhesion between the mold 200 and the test plate, making it easier to remove the test plate from the mold 200. Treating the convex mold, concave mold and stop bar of the mold 200 with the high temperature release agent can ensure that the adhesion between the mold 200 and the test plate is reduced during the pressing process, thereby preventing the test plate from being damaged when being removed. Performing two treatments can ensure that the release agent forms a uniform coating on the surface of the mold 200, further improving the demolding effect.

[0056] Through the above embodiments, the present application has the following beneficial effects or advantages: the composite autoclave high temperature molding vacuum sealing method disclosed in the present application uses aluminum foil (or glass fiber reinforced aluminum foil) to make a vacuum bag 100, and uses a folded vacuum bag 100 for sealing and compression, which effectively solves the problem of vacuum leakage caused by damage to the nylon vacuum-assisted bag film under high temperature and high pressure conditions, and prepares a composite material product with good internal quality. It solves the vacuum leakage problem during the curing process of high temperature resistant materials such as polyimide, and provides an optional vacuum-assisted material for the molding of products with high temperature resistance and certain functionality.

[0057] The composite material autoclave high temperature molding vacuum sealing method disclosed in the present application can be operated in the following manner, which generally includes the following main steps:

[0058] Step 1: Assembling the molding die 200;

[0059] Step 2: Laying of prepreg;

[0060] Step 3: vacuum packing of the mold 200;

[0061] Step 4: Autoclave curing;

[0062] Step 5: Demoulding.

[0063] Assembly of the forming mold 200: A composite material flat plate forming mold 200 is used, including a concave mold, a convex mold, a limit stop bar, a lifting bolt, etc. The main structure of the mold 200 is a concave mold and a convex mold. Inside the concave mold, a pad is set under the product to ensure that the product is evenly heated and pressed, has uniform thickness, and can be demoulded without loss.

[0064] Laying of prepreg: Before laying the prepreg, clean the surface of the tooling to remove abnormalities such as surface glue marks or sharp protrusions to avoid damaging the vacuum bag 100 film; cut the prepreg cloth into corresponding sizes, and then lay the prepreg cloth layer by layer in the cavity of the mold 200 according to the laying order. Each time a layer of prepreg cloth is laid, a polytetrafluoroethylene strip is used to drive out air, press and compact it. Repeat this operation until all the designed prepreg cloth layers are laid.

[0065] Vacuum packing of mold 200: Before vacuum packing, mold 200 is first processed, mainly filling the screw holes on the surface of mold 200 to prevent the vacuum bag 100 film above the pores from being sunken downwards under vacuum pressure during vacuuming. According to the size of mold 200, cut the vacuum bag 100 of appropriate size, flatten the vacuum bag 100, and place a layer of polytetrafluoroethylene cloth or glass fiber cloth on the inner surface of the vacuum bag 100, and then place the mold 200 in the vacuum bag 100. Lay a layer of breathable material on the mold 200, fold the vacuum bag 100 to wrap the mold 200, reserve holes according to the size of the vacuum nozzle 400, install the vacuum nozzle 400, use the silicone rubber sheet 300 for sealing, and tighten the vacuum nozzle 400. By folding the four sides of the vacuum bag 100, the edge of the vacuum bag 100 is folded multiple times, and the vacuum bag 100 is sealed by clamping with a bow clip 500. The vacuum bag 100 is evacuated, and when the vacuum value in the vacuum bag 100 reaches a first preset value, the vacuum system is turned off to ensure that the decrease in the vacuum value in the vacuum bag 100 within a predetermined time is less than a second preset value.

[0066] Among them, the first preset value can be set to 0.098Mpa, the second preset value can be set to 0.013Mpa, and the predetermined time can be set to 10min.

[0067] Autoclave curing: During the autoclave curing process, the vacuum state is maintained, and pressurization and multiple heating, insulation and exhaust operations are performed, and the temperature is controlled at 225-320°C. When the temperature reaches 280°C, pressurization is performed until the pressure reaches 3MPa. When the temperature reaches 320°C, curing begins.

[0068] Demolding: After the mold 200 is cooled, the vacuum bag 100 and the mold 200 are disassembled to take out the product.

[0069] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described above in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0070] Therefore, the above detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. 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.

[0071] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0072] In the description of the present invention, it is necessary to understand that the terms indicating orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0073] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0074] In the present invention, unless otherwise clearly specified and limited, a first feature being above or below a second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through another feature between them. Moreover, a first feature being above, above, and above a second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being below, below, and below a second feature includes the first feature being directly below and obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0075] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0076] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A composite material autoclave high temperature molding vacuum sealing method, characterized in that: The steps include: Place the product into the mold; According to the size of the mold, cut a vacuum bag of appropriate size, flatten the vacuum bag, place a layer of polytetrafluoroethylene cloth or glass fiber cloth on the inner surface of the vacuum bag, and then place the mold in the vacuum bag; Laying a layer of breathable material on the mold, folding the vacuum bag to wrap the mold, reserving a hole according to the size of the vacuum nozzle, installing the vacuum nozzle and sealing it with a silicone rubber sheet, tightening the vacuum nozzle, and sealing the vacuum bag; The vacuum bag is evacuated, and when the vacuum value in the vacuum bag reaches a first preset value, the vacuum system is turned off to ensure that the decrease in the vacuum value in the vacuum bag within a predetermined time is less than a second preset value; Carry out autoclave curing and cooling after curing; After the mold is cooled, the vacuum bag is removed and demoulding is performed to take out the product; The vacuum bag material is aluminum foil or glass fiber reinforced aluminum foil.

2. The composite material autoclave high temperature molding vacuum sealing method according to claim 1, characterized in that: The thickness of the aluminum foil or the glass fiber reinforced aluminum foil is 0.2-0.5 mm.

3. The composite material autoclave high temperature molding vacuum sealing method according to claim 1, characterized in that: Before placing the product into the mold, the prepreg is first cut into corresponding sizes, and the prepreg is laid layer by layer in the mold cavity according to the laying order. Each time a layer of the prepreg is laid, a polytetrafluoroethylene strip is used to drive out air, press and compact it. This operation is repeated until all the designed prepreg layers are laid.

4. The composite material autoclave high temperature molding vacuum sealing method according to claim 1, characterized in that: Before the vacuum bag is wrapped outside the mold, the screw holes on the surface of the mold are first filled and leveled.

5. The composite material autoclave high temperature molding vacuum sealing method according to claim 1, characterized in that: When the vacuum bag is wrapped around the mold, the breathable material is polytetrafluoroethylene cloth or glass fiber cloth.

6. The composite material autoclave high temperature molding vacuum sealing method according to claim 1, characterized in that: The vacuum bag is sealed by folding the four sides of the vacuum bag, folding the edges of the vacuum bag multiple times, and then clamping the vacuum bag with a bow-shaped clamp.

7. The composite material autoclave high temperature molding vacuum sealing method according to any one of claims 1 to 6, characterized in that: During the autoclave curing process, the vacuum state is maintained, and pressurization, heating, insulation and exhaust operations are performed multiple times, and the temperature is controlled at 225-320℃.

8. The composite material autoclave high temperature molding vacuum sealing method according to claim 7, characterized in that: During the autoclave curing process, when the temperature reaches 280°C, pressurization is performed until the pressure reaches 3MPa, and when the temperature reaches 320°C, curing begins.

9. The composite material autoclave high temperature molding vacuum sealing method according to any one of claims 1 to 6, characterized in that: After the mold is cooled to below 60° C., the autoclave is opened, the vacuum bag is removed and demoulding is performed.

10. The composite material autoclave high temperature molding vacuum sealing method according to any one of claims 1 to 6, characterized in that: The stop bar is selected according to the thickness of the pressing test plate, the tooling is cleaned with anhydrous ethanol, and the punch, die and stop bar of the mold are treated with a high-temperature release agent twice.

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