Preparation method of vacuum bag for vacuumizing treatment

Abstract

The invention relates to a preparation method of a vacuum bag for vacuumizing treatment, which comprises the following steps of: providing a clean and flat mold, placing a substrate to be packaged on the mold, and covering a breathable layer on the surface of the substrate to be packaged; a whole sealing rubber strip is selected and continuously laid from any corner of the mold along the edge of the mold corresponding to the edge of the breathable layer, three-side U-shaped sealing is completed, pre-folding marks are formed before the sealing rubber strip enters the corner, the inner side of the sealing rubber strip is shrunk and deformed, the outer side of the sealing rubber strip is stretched and deformed, and the sealing rubber strip is attached along the cambered surface of the corner of the mold; the straight line sections and the corner sections are compacted; tearing off the protective films of the sealing rubber strips on the front three sides, covering the protective films with vacuum bag films, and compacting and attaching the vacuum bag films along the sealing rubber strips on the three sides; on the fourth edge, the sealing rubber strip is reversely lapped to the U-shaped opening in the mode that the pasting face faces upwards and the protective film faces downwards, then the protective film is torn off, the redundant sealing rubber strip is pleated and compacted at the position away from the corner, and therefore the sealing structure is formed.

Description

Technical Field

[0001] This invention relates to the field of carbon fiber composite material molding technology, and in particular to a method for preparing a vacuum bag for vacuuming. Background Technology

[0002] In material forming, lamination curing, vacuum induction, and related heat treatment processes, it is usually necessary to vacuum the substrate to be packaged. A common method involves placing the substrate on a mold or support platform, then using sealing strips to create a sealed boundary and covering it with a vacuum bag film. This connects the enclosed space to the vacuum equipment, allowing compaction, degassing, or curing to occur under negative pressure. The quality of the vacuum bag preparation directly affects the speed and stability of vacuum establishment and the quality of subsequent processing; therefore, the integrity and reliability of the sealing structure are critical technical aspects.

[0003] In existing technologies, the formation of a sealing boundary typically relies on a sealing strip laid along the mold edge and covered with a vacuum bag film to complete the sealing structure. Since the mold edge often includes straight sections and corner transition areas, and the vacuum bag film needs to be sequentially bonded to the sealing strip and mold during the sealing process, it is easily affected by material elastic deformation, bonding sequence, and local stress distribution in actual operation, resulting in differences in the bonding state of the sealing boundary in different areas. This difference may not be obvious in the initial stage of vacuuming, but during continuous negative pressure or temperature rise, localized uneven deformation of the sealing boundary may lead to a decrease or fluctuation in vacuum stability, thus affecting the consistency of the sealing effect.

[0004] When the substrate to be encapsulated is a composite laminate, especially a carbon fiber composite, higher requirements are placed on the sealing performance of the encapsulation structure. During heat treatment or curing, carbon fiber composites typically involve resin flow and volatile release, requiring continuous venting and compaction under stable negative pressure. Poor sealing can easily lead to defects such as internal pores, bubbles, delamination, or localized resin accumulation. Furthermore, these substrates are often laid on mold surfaces with a certain curvature or corners, and the adhesion quality of the sealing strip at the corners directly affects the continuity of the vacuum boundary. The sealing structure must maintain stable adhesion in straight sections and adapt to deformation at corners to avoid stress concentration or detachment caused by forced bending.

[0005] Therefore, during the vacuuming process, there is a need for a vacuum bag preparation method that can form a continuous shape at the edge of the mold, reduce overlap, adapt to corner shapes, and avoid the formation of air channels during the sealing process, so as to improve the overall reliability and vacuum stability of the sealing structure. Summary of the Invention

[0006] This invention covers the following technical solutions: This invention relates to a method for preparing a vacuum bag for vacuuming, comprising the following steps: A clean and flat mold is provided, the substrate to be packaged is placed on the mold, and a breathable layer is covered on the surface of the substrate to be packaged; A single sealing strip is selected and continuously laid along the edge of the mold corresponding to the edge of the breathable layer, starting from any corner of the mold, to complete a three-sided U-shaped seal. A pre-fold is formed before the sealing strip enters the corner, causing the inner side of the sealing strip to shrink and the outer side to stretch, and it is then adhered to the arc surface of the mold corner to compact the straight section and the corner section. Remove the protective film from the three front sealing strips, cover it with the vacuum bag film, and press it firmly along the three sealing strips; On the fourth side, the sealing strip is overlapped with the adhesive side facing up and the protective film facing down at the U-shaped opening. The vacuum bag film is first attached to the sealing strip on the fourth side, and then the protective film is removed. The sealing strip on the fourth side is then attached to the mold from the overlap on both sides toward the center. Any excess sealing strip is pleated and compacted away from the corner, thus forming a sealed structure.

[0007] This invention utilizes a three-sided integrated continuous sealing, pre-folding deformation control at corners, and a fourth-sided reverse bonding method to ensure a continuous and uniform bonding interface for the sealing strip at both straight sections and corners. This reduces local deformation instability and uneven bonding, thereby improving the overall continuity and stability of the sealing boundary. This method is beneficial for increasing the speed of vacuum build-up and the stability of negative pressure maintenance, reducing the risk of vacuum fluctuations, simplifying the operation process, improving preparation efficiency, and enhancing adaptability to different mold shape conditions. Attached Figure Description

[0008] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0009] Figure 1 : Schematic diagram of mold pretreatment and laying auxiliary materials.

[0010] Figure 2 : Schematic diagram of corner folding shape.

[0011] Figure 3 : Schematic diagram of sealing strips pasted on 3 sides of the mold and covered with vacuum bag film.

[0012] Figure 4 : Schematic diagram of attaching the sealing strip to the 4th side of the vacuum bag film (the sealing strip is placed in reverse).

[0013] Figure 5: A schematic diagram of the fourth sealing strip being attached to the mold.

[0014] Figure 6 : Diagram showing how to pinch and pleat excess sealing strip.

[0015] Reference numerals: Mold-1; Release film-2; Release cloth-3; Breathable felt-4; Carbon fiber composite material-5; Vacuum base-6; Adhesive strip-7; Vacuum bag film-8; Protective film-9; Corner B-10; Corner C-11; Reverse-attached fourth-side sealing strip-12; Pleated area-13; Corner A-14; Corner D-15. Detailed Implementation

[0016] Reference will now be made to detailed embodiments of the present invention, one or more of which are described below. Each example is provided for explanation and not for limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to the invention without departing from its scope or spirit. For example, features described or illustrated as part of one embodiment may be used in another embodiment to produce further embodiments.

[0017] Unless otherwise stated, all terms used to disclose this invention (including technical and scientific terms) should be understood as having the meaning commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of protection of this invention. Unless the context clearly defines otherwise, the scientific and technical terms used herein, as well as terms and laboratory procedures in related fields such as composite materials engineering, polymer materials and adhesives technology, engineering mechanics, manufacturing process engineering, and fluid mechanics, are all conventional terms and standard methods well-known and widely used in the art. To facilitate understanding of the technical solutions of this invention, some related terms are further defined and explained below.

[0018] As used herein, the terms “and / or,” “or / and,” and “and / or” encompass any one of two or more of the relevant listed items, as well as any and all combinations of the relevant listed items, including any two of the relevant listed items, any more of the relevant listed items, or a combination of all the relevant listed items.

[0019] The terms “containing,” “comprising,” and “including” as used in this invention are synonyms and are inclusive or open-ended, not excluding additional, uncited members, elements, or method steps.

[0020] In this invention, the numerical range represented by endpoints includes all numerical values ​​and fractions contained within that range, as well as the endpoints mentioned.

[0021] Furthermore, in describing representative embodiments of the invention, this specification may present the methods and / or processes of the invention as a specific sequence of steps. However, the method or process should not be limited to the specific order of the steps described herein, to the extent that the method or process does not depend on the specific order of the steps presented herein. As will be understood by those skilled in the art, other sequences of steps are also possible. Therefore, the specific order of steps presented in the specification should not be construed as a limitation of the claims. Additionally, the claims relating to the methods and / or processes of the invention should not be limited to the execution of their steps in the order they are written, and those skilled in the art will readily recognize that the sequence can be changed while still remaining within the spirit and scope of the invention.

[0022] As used in this invention, unless otherwise stated, the singular forms of the articles “a,” “an,” and “the” include plural referents.

[0023] In this invention, the terms "multiple" or "various" are used unless otherwise specified, referring to a quantity greater than or equal to 2.

[0024] In this invention, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions that include the listed features.

[0025] In this invention, terms such as "preferred," "better," "more suitable," and "ideal" merely describe implementation methods or embodiments with better effects and should be understood not to limit the scope of protection of this invention. In this invention, terms such as "optionally," "optionally," and "optional" mean that something is optional, that is, selected from either "with" or "without" a parallel solution. If multiple "optional" statements appear in a technical solution, unless otherwise specified and without contradiction or mutual constraint, each "optional" statement is independent.

[0026] In this invention, the term "vacuum bag preparation method" refers to a process in which a sealing strip is set around a mold and a vacuum bag film is used to form a closed space, so that the closed space can be connected to a vacuum device and a negative pressure environment is established.

[0027] In this invention, the term "substrate to be packaged" refers to a material or component that requires vacuum treatment, which may be a laminate, sheet material or other structure.

[0028] In this invention, the term "mold" refers to a structure or support platform used to carry the substrate to be packaged and define its shape or provide support.

[0029] In this invention, the term "permeable layer" refers to a material layer disposed on the surface of the substrate to be encapsulated, used to provide a gas channel to enable gas flow during the vacuuming process.

[0030] In this invention, the term "sealing strip" refers to a strip-shaped sealing material with adhesive properties and a certain degree of elastic deformation, used to form a sealing boundary around the mold. Its material can be rubber, butyl rubber, or other elastomer materials with good airtightness and temperature resistance. The sealing strip has a certain degree of softness and plasticity at room temperature, facilitating continuous laying along the mold edge and adapting to shape changes at corners; it maintains structural stability under negative pressure and heat treatment conditions, and is not prone to significant flow or loss of adhesion; its adhesive surface can be pre-coated with pressure-sensitive adhesive or self-adhesive material. At least one side of the sealing strip is covered with a peelable protective film; the protective film is used to isolate the adhesive surface during laying and positioning, preventing the sealing strip from adhering to the mold or vacuum bag film in advance, thereby facilitating the positioning, adjustment, and step-by-step bonding of the sealing strip. When bonding is required, the protective film is removed to expose the adhesive surface and form a sealed connection.

[0031] In this invention, the terms "three sides," "fourth side," and "U-shaped" are relative expressions used only to facilitate the description of the laying sequence and spatial relationship of the sealing strip, and do not limit specific orientations or absolute geometric shapes. "Three sides" generally refers to three connected boundary segments formed by the continuous laying of the sealing strip along the perimeter of the mold; "fourth side" generally refers to the remaining boundary segment used to close the openings of the three boundary segments; and "U-shaped" refers to an opening structure formed by the continuous laying of the sealing strip along the three sides of the mold, with U-shaped openings at both ends.

[0032] In this invention, the term "pre-crease" refers to the deformation guide line formed in the width direction of the sealing strip before it enters the corner area, which is used to control the deformation mode of the sealing strip on the inner and outer sides at the corner.

[0033] In this invention, the term "reverse setting" refers to the operation method in which the sealing strip is placed with its adhesive side facing up and the protective film facing down, so that it first adheres to the vacuum bag film and then adheres to the mold.

[0034] In this invention, the term "vacuum nozzle" refers to an interface component installed on a vacuum bag membrane for communicating with a vacuum device to achieve vacuuming.

[0035] In this invention, the term "sealing structure" refers to the closed boundary structure surrounding the substrate to be packaged, formed by the sealing strip and the vacuum bag film.

[0036] This invention relates to a method for preparing a vacuum bag for vacuuming, comprising the following steps: A clean and flat mold is provided, the substrate to be packaged is placed on the mold, and a breathable layer is covered on the surface of the substrate to be packaged; A single sealing strip is selected and continuously laid along the edge of the mold corresponding to the edge of the breathable layer, starting from any corner of the mold, to complete a three-sided U-shaped seal. A pre-fold is formed before the sealing strip enters the corner, causing the inner side of the sealing strip to shrink and the outer side to stretch, and it is then adhered to the arc surface of the mold corner to compact the straight section and the corner section. Remove the protective film from the three front sealing strips, cover it with the vacuum bag film, and press it firmly along the three sealing strips; On the fourth side, the sealing strip is overlapped with the adhesive side facing up and the protective film facing down at the U-shaped opening. The vacuum bag film is first attached to the sealing strip on the fourth side, and then the protective film is removed. The sealing strip on the fourth side is then attached to the mold from the overlap on both sides toward the center. Any excess sealing strip is pleated and compacted away from the corner, thus forming a sealed structure.

[0037] This method, by controlling the laying sequence and deformation mode, helps to improve the continuity of the sealing boundary and the stability of the vacuuming process.

[0038] The mold described in this invention refers to a mold used to support the substrate to be packaged and serve as a boundary reference for laying the sealing strip. Its surface is generally clean, dry, and free of oil, dust, and other adhering impurities to minimize any impact on the adhesion performance of the sealing strip. The mold surface typically has good flatness, with no obvious unevenness, scratches, or local undulations within the sealing strip laying area, allowing the sealing strip to form a continuous and uniform bonding interface. The mold can be plate-shaped, frame-shaped, or a structure with a certain curvature. Its edges may include straight segments transitioning to rounded or arc-shaped corners. Preferably, the corner areas have continuous transition surfaces to facilitate the deformation and bonding of the sealing strip. To ensure structural stability during vacuuming, the mold is preferably a rigid structure, capable of maintaining its shape without significant deformation under negative pressure and subsequent heat treatment conditions, thereby providing stable support for the sealing structure.

[0039] In a preferred embodiment, to ensure the sealing strip is laid flat and facilitates compaction, the mold edges corresponding to the three sides and the fourth side are preferably basically straight, thus facilitating the formation of a continuous bonding interface for the sealing strip. However, in practical applications, the mold edges may also have a certain curvature or radius. As long as this curvature does not significantly affect the continuous bonding and sealing stability of the sealing strip, the technical effects of the present invention can still be achieved. Therefore, the above descriptions of "three sides," "fourth side," and "U-shaped" should not be construed as limiting the mold edges to be strictly straight lines or standard geometric shapes.

[0040] The breathable layer is preferably a porous material layer with good gas conductivity and structural stability under vacuum and heating conditions. It can be made of breathable felt, breathable cloth, porous nonwoven fabric, or other materials with continuous pore structures. The breathable layer preferably has sufficient porosity and connectivity to form a stable gas flow channel during vacuuming, ensuring uniform pressure across all areas of the substrate surface to be packaged. Simultaneously, its temperature resistance preferably meets the temperature requirements of the expected vacuuming or heat treatment process, preventing significant shrinkage, collapse, or structural damage under negative pressure and temperature. The thickness of the breathable layer can be selected based on the substrate size and the length of the evacuation path to ensure smooth gas discharge while avoiding localized lifting or stress concentration on the vacuum bag membrane, thereby forming a stable negative pressure environment in conjunction with the sealing structure.

[0041] The vacuum bag film is used to cover the sealing strip and form a closed space with the mold. Its material is preferably a flexible film material with good airtightness and temperature resistance, such as a high-temperature resistant composite film or a multi-layered polymer film. The vacuum bag film preferably has a certain degree of transparency to allow observation of the internal bonding state and substrate condition during vacuuming and heat treatment, but opaque materials can also be selected depending on the actual application. The vacuum bag film should have sufficient flexibility and extensibility to adapt to shape changes in the mold edges and corner areas, and should be able to adhere to the breathable layer and the surface of the substrate to be packaged under negative pressure without easily breaking. Its thickness can be selected according to the process temperature, negative pressure level, and substrate size, typically choosing a range that can maintain structural stability under vacuum and heating conditions without significant shrinkage or perforation, thus helping to maintain the stability of the closed space.

[0042] In a preferred embodiment of the present invention, the depth of the pre-crease is 1 / 3 to 1 / 2 of the thickness of the sealing strip. By controlling the depth of the pre-crease within the above range, the deformation of the sealing strip in the corner area can be guided without significantly weakening the overall structural strength of the sealing strip. When the pre-crease depth is less than this range, the guiding effect on the deformation of the inner and outer sides may not be obvious; when the pre-crease depth is too large, it may affect the overall continuity of the sealing strip. Controlling the pre-crease depth to 1 / 3 to 1 / 2 of the thickness of the sealing strip is beneficial to forming a relatively uniform adhesion state of the sealing strip at the corner arc surface, improving the stability of the sealing boundary. The above numerical range is a preferred range, and those skilled in the art can make appropriate adjustments according to the material, thickness of the sealing strip and the shape of the mold corner.

[0043] In some embodiments, the compaction operation includes rolling a roller along the width of the sealing strip to expel air between the sealing strip and the mold. The roller can be a rubber roller, a silicone roller, or other compaction tool with a certain degree of elasticity. By applying pressure through rolling along the width of the sealing strip, the interface between the sealing strip and the mold gradually comes into contact, which helps to reduce interface gaps and make the contact pressure distribution more uniform, thereby improving the continuity of the sealing boundary. The rolling compaction can be gradually advanced along a straight segment, achieving stable adhesion without significantly altering the overall shape of the sealing strip.

[0044] In a further embodiment, after compaction of the corner section, point-pressing is applied to the folded area to maintain the sealing strip in an adherent state within its elastic deformation range. This point-pressing can be achieved by applying pressure with fingers or a flexible pressure block to further adhere the sealing strip to the corner area of ​​the mold within its elastic deformation range. By applying localized point-pressing on top of rolling compaction, the adhesion of the corner area is improved, reducing local undulations caused by concentrated deformation, thereby enhancing the stability of the sealing boundary at the corner.

[0045] In some embodiments, before the fourth sealing strip is reversed and placed at the U-shaped opening, two sections of protective film are cut and pasted to both ends of the three-sided U-shaped sealing structure to prevent the vacuum bag film from prematurely adhering to the three-sided sealing strip. The length of the two protective film sections is preferably 5cm to 10cm, covering the end adhesive surface of the three-sided sealing strip, temporarily isolating this area during the vacuum bag film covering process, thus preventing the vacuum bag film / fourth-sided sealing strip from prematurely adhering to the three-sided sealing strip before positioning. This method facilitates control over the laying sequence of the vacuum bag film, ensuring it is first adhered in a predetermined area before the reverse sealing operation of the fourth side, thereby improving the overall controllability and uniformity of the adhesion; it also allows for sufficient operating space when operating on the fourth side. The protective film can be removed in subsequent steps to restore the adhesive function of the end area and form a complete sealing boundary.

[0046] In some embodiments, after the fourth side is sealed, a hole is made at the position corresponding to the breathable layer of the vacuum bag film, and a vacuum nozzle is installed to connect the vacuum nozzle to the breathable layer. The vacuum nozzle can be a conventional vacuum interface structure, which establishes negative pressure by connecting to a vacuum device.

[0047] In some embodiments, after the vacuum nozzle is installed, the surrounding sealing strip and vacuum bag film are re-compacted to improve the continuity of the seal. Local compaction of the interface area helps improve the continuity of the fit in that area, reduces gaps caused by deformation differences at the interface, and thus enhances the stability of the overall sealing boundary.

[0048] In some embodiments, a separator is provided between the substrate to be encapsulated and the breathable layer to prevent the resin system from adhering to the upper material. The separator can be a thin film material with certain temperature resistance, such as polytetrafluoroethylene film, fluorinated polymer film, polyester film, or other heat-resistant polymer films. Preferably, the separator has low surface adhesion to reduce the possibility of the resin system adhering to the upper material during curing or heating. The separator should generally have a certain degree of flexibility to adapt to changes in the surface shape of the substrate to be encapsulated, and should be able to conform to the substrate surface under negative pressure without significant cracking or shrinkage. Its thickness can be selected according to the specific process temperature and the flow characteristics of the resin system, ensuring the isolation effect without significantly affecting the gas conductivity of the breathable layer. The material and thickness of the separator can be adjusted according to the type of substrate to be encapsulated and the vacuuming or heat treatment conditions, as long as it can maintain structural stability under the process environment and achieve a certain degree of protection for the surface structure of the substrate to be encapsulated.

[0049] In some embodiments, a release layer is further provided between the separator and the breathable layer. This release layer is used to separate the product from the auxiliary materials after curing. The release layer can be a woven or nonwoven material with a certain porous structure and temperature resistance, such as fiberglass cloth, polyester fiber cloth, nylon fabric, or porous nonwoven fabric. Preferably, the release layer has continuous pore channels to form a gas flow path with the breathable layer during vacuuming, and can separate from the product and upper materials after curing or heat treatment. The release layer typically possesses a certain degree of flexibility to adapt to the shape changes of the substrate surface to be packaged, and can adhere to the substrate surface under negative pressure without significant wrinkling or tearing. Its thickness and fabric density can be selected according to the substrate size, resin system flowability, and process temperature, satisfying gas conduction and separation requirements without significantly affecting the adhesion of the vacuum bag film. The specific material and structure of the release layer can be adjusted according to actual application conditions, as long as it can maintain structural stability and achieve separation under vacuum and heat treatment environments.

[0050] In some embodiments, the substrate to be encapsulated is a composite material laminate.

[0051] In some embodiments, the composite laminate is a fiber-reinforced resin-based composite material. The fiber reinforcement can be in the form of continuous fibers or fabric reinforcement, and the resin matrix can be a thermosetting resin or a thermoplastic resin system. Vacuuming this type of material facilitates the removal of internal gases during processing and enables interlayer bonding.

[0052] In a further embodiment, the fiber-reinforced resin-based composite material is a carbon fiber composite material. Carbon fiber composite materials typically experience resin flow and volatile release during heat treatment or curing, requiring high stability under negative pressure. When the vacuum bag preparation method of this invention is applied to carbon fiber composite materials, it helps improve the stability of the sealing boundary, thereby enhancing the continuity and controllability of the vacuuming process.

[0053] The embodiments of the present invention will be described in detail below with reference to the examples. It should be understood that these embodiments are only used to illustrate the technical content of the present invention and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the specific experimental conditions in the following embodiments are given priority reference to the guidelines provided in this specification, or may be carried out according to generally accepted experimental manuals or conventional experimental conditions, or other experimental methods known in the art, or according to the conditions recommended by the relevant reagent or instrument manufacturers. In specific embodiments, unless otherwise specified, minor deviations within the weighing accuracy range are allowed for the measurement parameters involving raw material components; reasonable deviations due to instrument detection accuracy or operational accuracy are also allowed for parameters such as temperature and time.

[0054] Example This embodiment provides a method for preparing a vacuum bag made of carbon fiber composite material for vacuuming.

[0055] 1. Mold pretreatment: Clean the mold to remove oil, dust and other impurities, wipe it with anhydrous ethanol and let it air dry.

[0056] 2. Laying auxiliary materials: such as Figure 1 As shown, carbon fiber composite material-5 (as the substrate to be treated) is placed on mold-1, and then release film-2 (to prevent the composite material from sticking to other layers), release cloth-3 (to facilitate subsequent demolding), and breathable felt-4 (to ensure smooth airflow during vacuum extraction) are laid in sequence. Each layer should be laid flat and without wrinkles. A vacuum base-6 is placed on the breathable felt at the corner of the mold. A double layer of breathable felt with the same shape as the vacuum base is cut and put on the vacuum base (to eliminate the influence of the height difference of the vacuum base and ensure smooth airflow during vacuum extraction).

[0057] 3. Sealing strip positioning and straight section pasting: Select a high-elasticity, high-temperature resistant sealing strip. Take any corner of the mold as the starting point (marked as corner A). Align one end of the long sealing strip with the starting point and lay it along the edge of the mold until it is about to enter the corner position. The outer edge of the sealing strip should be flush with the outer edge of the sealing area of ​​the mold. Use a silicone roller to gradually compact the sealing strip from the starting point to make the sealing strip initially adhere to the mold surface, thus completing the pasting of the first straight section.

[0058] 4. Paste at corners: For the mold corners B and C, a folding method of "diagonal pre-folding + curved surface bonding" is adopted, as follows: ① Identify the inner and outer sides of the corner corresponding to the sealing strip: the side closer to the mold edge is the outer side, and the side farther away from the mold edge is the inner side.

[0059] ② Pre-folding operation: such as Figure 2 As shown, when the sealing strip is about to enter the corner (10-15mm from the corner apex), use your finger to apply slight pressure outward along the center line of the sealing strip's width direction. This will create an "arc pre-crease" on the inner side of the sealing strip that matches the corner's curvature. The depth of the pre-crease should be 1 / 3 to 1 / 2 of the sealing strip's thickness. This ensures that the inner side of the sealing strip naturally bends along the pre-crease when folding, avoiding wrinkling due to compression.

[0060] ③ Adhesion and shaping: The pre-folded sealing strip is adhered to the arc surface of the mold corner, so that the outer side of the strip is naturally stretched and the inner side shrinks along the pre-fold line, forming a coordinated deformation of "outer stretching-inner shrinkage". Finally, the sealing strip and the mold corner form a complete surface contact. After folding, the sealing strip is wrinkle-free and unbroken, and the thickness of the sealing strip at the corner is uniform (the thickness deviation from the straight section is ≤0.5mm).

[0061] ④ Compaction Operation: Pre-compaction: Use a silicone roller with a diameter of 10-15mm to roll and compact from the inside to the outside along the width of the sealing strip, expelling air from the contact surface between the sealing strip and the mold, and ensuring that the bottom of the sealing strip is completely in contact with the mold surface; Final compaction: Apply point-pressing to the corner area after folding, so that the sealing strip forms a tight fit with the corner of the mold within the elastic deformation range, and use the rebound characteristics of the sealing strip to maintain the bonding pressure.

[0062] 5. Apply sealing strips to the three sides of the mold: Starting from corner A, use a straight-segment application method to lay the sealing strip along the first edge of the mold to corner B. Use the corner application method to fold and compact corner B. Use a straight-segment application method to lay the sealing strip along the second edge of the mold to corner C. Use the corner application method to fold and compact corner C. Use a straight-segment application method to lay the sealing strip along the third edge of the mold to corner D, completing the application of the integrated sealing strip on all three sides of the mold.

[0063] 6. For example Figure 3As shown, the mold's three sides have been glued with adhesive strip-7 and covered with vacuum bag film-8. Remove the protective film from the sealing strip and cut two pieces of protective film-9, each 5cm-10cm long, and glue them to the beginning and end of the sealing strip, i.e., corners A and D, to prevent the vacuum bag film from sticking on prematurely. Support the four corners of the vacuum bag film to position it in the air, ensuring it completely covers the sealing strip while preventing it from sticking to it prematurely. First, glue and press the vacuum bag film to the sealing strip at corner B. Then, gradually glue the vacuum bag film and sealing strip along the second side of the mold to corner C, pressing and fixing them. Finally, gradually glue the vacuum bag film and sealing strip along the first and third sides of the mold, ensuring there are no air gaps between the vacuum bag film and the sealing strip, and good sealing on all three sides.

[0064] 7. Attaching the sealing strip to the fourth side of the vacuum bag film: Place the sealing strip upside down on the fourth side of the mold, with the sealing strip facing upwards and the protective film facing downwards, to prevent the sealing strip from being prematurely attached to the mold. Smooth the fourth side of the vacuum bag film. Starting from any side, gradually attach the vacuum bag film onto the sealing strip, ensuring there are no air gaps between the vacuum bag film and the sealing strip. The finished structure should look like this. Figure 4 As shown.

[0065] 8. Treat the fourth sealing strip: First, tear off the protective film at corners A and D in step 6, and then gradually stick and press the vacuum bag film to the sealing strip at that location. At this point, the length of the fourth side vacuum bag film is greater than or equal to the length of the remaining unsealed area of ​​the mold. For example... Figures 5-6 As shown, slowly peel off the protective film of the sealing strip pasted on the 4th side of the vacuum bag film. Gradually place the vacuum bag film with the sealing strip pasted on both sides onto the mold and press it firmly to ensure that the mold and the sealing strip are in contact. Pinch and pleat the excess sealing strip, leaving the pleated part -13 in the middle of the mold, avoiding the corners of the mold. Ensure that there are no air channels between the mold and the sealing strip, or in the pleats of the sealing strip. The vacuum bag preparation is now complete.

[0066] 9. Airtightness Check: Make an opening at the vacuum bag membrane above the vacuum base and install the vacuum nozzle; re-press the sealing strip, and press it again along the inner and outer edges of the sealing strip with your fingertips to ensure that the edges do not lift up and form a continuous sealing boundary. Connect the vacuum equipment to check the vacuum stability and check whether the vacuum bag seal is qualified.

[0067] Comparative Example To illustrate the differences between the method of the present invention and conventional processes, the following comparative examples are provided.

[0068] This comparative example also uses carbon fiber composite material as the substrate to be encapsulated and undergoes vacuum treatment.

[0069] First, mold pretreatment is carried out by laying carbon fiber composite material on the mold surface, and then laying release film, release cloth and breathable felt in sequence to make the substrate to be packaged in a vacuum state.

[0070] Then, segmented sealing strips are laid out section by section around the mold. For each side, sealing strips of the corresponding length are cut according to the mold length and pasted on. At corners, the ends of two sealing strips are overlapped to achieve a corner connection. After laying, the protective film on the sealing strips is removed, and the vacuum bag film is completely covered on top of the sealing strips and pressed firmly.

[0071] During the fourth sealing process, first, directly adhere the sealing strip to the remaining unsealed area of ​​the mold, then press the vacuum bag film onto the sealing strip. If there are any areas that are not properly sealed, compensate by adding short sections of sealing strip to the leaking areas, and then re-secure the vacuum bag film. After sealing, install the vacuum nozzle and perform a vacuuming operation.

[0072] The process described in the above comparative example is a common vacuum bag preparation method in the prior art. It differs from the embodiment of the present invention in terms of the sealing strip laying method, corner treatment method and the order of sealing the fourth side.

[0073] Experimental Example To characterize the difference in performance between the implementation examples and the experimental examples, their technical indicators were tested.

[0074] To ensure the comparability of the data between the examples and comparative examples, all samples were vacuum-treated using the same mold specifications (550 mm × 480 mm, right-angled rectangular mold), the same type of vacuum bag film (50 μm thick, temperature resistant 230℃), the same type of sealing strip (13mm*3mm cross-section, temperature resistant 230℃), and the same type of rotary vane vacuum pump (ultimate vacuum ≤ -0.098MPa). The vacuuming environment temperature was 23±2℃, and the relative humidity was 50±10%.

[0075] I. Vacuum Degree Testing Method The vacuum level was monitored in real time using a digital vacuum gauge installed between the vacuum nozzle and the vacuum pump, with a measurement accuracy of ±0.001 MPa. The time required to reach -0.095 MPa was recorded from the start of the vacuum pump. After continuous evacuation for 10 minutes, the vacuum pump was turned off and the system remained sealed. The vacuum level decay value within 10 minutes was recorded to characterize the airtightness of the sealing structure. The stable vacuum fluctuation value was the maximum fluctuation range of the vacuum gauge reading within 1 minute under continuous evacuation.

[0076] II. Methods for Testing the Flatness of Bag Film After the vacuum reached a stable state (vacuum maintained within the range of -0.095 MPa ± 0.002 MPa for more than 2 minutes), the surface morphology of the vacuum bag film was measured. The maximum wrinkle height was measured by the vertical distance from the highest wrinkle point on the bag film surface to the reference plane using a vernier depth gauge. The flat bonding area ratio was determined by photographing the bag film surface after vacuuming and using image analysis software to count the ratio of the area without obvious bulges or gaps to the total area. The number of corner wrinkles was determined by visually counting the number of obvious wrinkles at the four corners of the mold.

[0077] III. Explanation of Relevant Parameters and Testing Methods for Carbon Fiber Composite Materials The carbon fiber composite material is a T700 grade carbon fiber / PEEK prepreg laminate, and the layup method is [0]. 12 It is a unidirectional layup, with a total of 12 layers, each layer being 0.17 mm thick, for a total thickness of approximately 2 mm. The curing process is 190℃ × 2 h (heating rate 2℃ / min), and curing is completed under continuous vacuum.

[0078] Porosity was measured using the cross-section method. The cured composite material samples were polished, and the pore distribution was observed using a metallographic microscope. The pore area ratio was calculated using image analysis software. Three different regions were selected from each sample group for measurement, and the average value was taken.

[0079] The number of bubbles was determined by counting the number of visible bubbles with a diameter ≥ 0.5 mm within a 100 mm × 100 mm area. The layered area was determined by ultrasonic C-scan detection, and the area of ​​the layered region was counted.

[0080] IV. Mechanical Property Testing Methods Tensile strength was tested according to GB / T 3354, with a specimen size of 250 mm × 15 mm and a loading rate of 2 mm / min. Interlaminar shear strength (ILSS) was tested according to the short beam method of GB / T 3357, with a span-to-thickness ratio of 4:1. Flexural strength was tested according to the three-point bending method of GB / T 3356. Each test group consisted of no fewer than 5 specimens, and the average value was taken as the final result.

[0081] V. Statistical Methods for Operational Efficiency Vacuum bag filling time refers to the total time required from the initial application of the sealing strip to the completion of the sealing structure and the achievement of a stable vacuum. The number of times additional sealing strips are applied during the vacuuming process due to air leakage. The number of times the strips need to be reapplied due to sealing failure refers to the number of times the strips need to be torn open and reapplied.

[0082] The experimental results are as follows: 1. Vacuum degree detection ; 2. Flatness of the bag film after vacuuming ; 3. Molding quality of carbon fiber composite materials ; 4. Improved mechanical properties (sealing effect affects air bubbles → affects strength) ; 5. Operational efficiency of the example ; The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A method for preparing a vacuum bag for vacuuming, characterized in that, Includes the following steps: A clean and flat mold is provided, the substrate to be packaged is placed on the mold, and a breathable layer is covered on the surface of the substrate to be packaged; A single sealing strip is selected and continuously laid along the edge of the mold corresponding to the edge of the breathable layer, starting from any corner of the mold, to complete a three-sided U-shaped seal. A pre-fold is formed before the sealing strip enters the corner, causing the inner side of the sealing strip to shrink and the outer side to stretch, and it is then adhered to the arc surface of the mold corner to compact the straight section and the corner section. Remove the protective film from the three front sealing strips, cover it with the vacuum bag film, and press it firmly along the three sealing strips; On the fourth side, the sealing strip is overlapped with the adhesive side facing up and the protective film facing down at the U-shaped opening. The vacuum bag film is first attached to the sealing strip on the fourth side, and then the protective film is removed. The sealing strip on the fourth side is then attached to the mold from the overlap on both sides toward the center. Any excess sealing strip is pleated and compacted away from the corner, thus forming a sealed structure.

2. As described in claim 1, characterized in that, The depth of the pre-crease is 1 / 3 to 1 / 2 of the thickness of the sealing strip.

3. The method for preparing a vacuum bag according to claim 1, characterized in that, The compaction operation includes rolling a roller along the width of the sealing strip to compact it, thereby removing air between the sealing strip and the mold.

4. The method for preparing a vacuum bag according to claim 3, characterized in that, After compacting the corner section, apply spot pressure to the folded area to keep the sealing strip in place within its elastic deformation range.

5. The method for preparing a vacuum bag according to claim 1, characterized in that, Before the fourth sealing strip is reversed and placed at the U-shaped opening, two sections of protective film are cut and pasted to the beginning and end of the three-sided U-shaped sealing structure to prevent the vacuum bag film from prematurely adhering to the three-sided sealing strip.

6. The method for preparing a vacuum bag according to claim 1, characterized in that, After the fourth side is sealed, a hole is made at the position of the air-permeable layer corresponding to the vacuum bag film and a vacuum nozzle is installed so that the vacuum nozzle is connected to the air-permeable layer. Optionally, after the vacuum nozzle is installed, the surrounding sealing strip and vacuum bag film are re-compacted to improve the continuity of the seal.

7. The method for preparing a vacuum bag according to claim 1, characterized in that, An isolation membrane is provided between the substrate to be encapsulated and the breathable layer, the isolation membrane being used to prevent the resin system from adhering to the upper material; Optionally, a release layer is further provided between the isolation membrane and the breathable layer, the release layer being used to separate the product from the auxiliary materials after curing.

8. The method for preparing a vacuum bag according to claim 1, characterized in that, The substrate to be encapsulated is a composite material laminate.

9. The method for preparing a vacuum bag according to claim 8, characterized in that, The composite laminate is a fiber-reinforced resin-based composite material.

10. The method for preparing a vacuum bag according to claim 9, characterized in that, The fiber-reinforced resin-based composite material is a carbon fiber composite material.

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