A method for forming a thin-walled irregular stringer and a forming mold

Abstract

This invention relates to the field of thin-walled truss forming technology, specifically to a method and mold for forming ply-laminated thin-walled irregular trusses. The method includes the following steps: S1: Inspect the surfaces of the upper and lower molds for any protrusions or burrs, and assemble them using room-temperature curing adhesive, ensuring the edges of the upper and lower molds are aligned without misalignment to form a core mold; S2: Apply a release agent to the surface of the stretchable film at least three times, allow it to dry, and then apply it sequentially and naturally onto the surface of the assembled core mold using room-temperature curing adhesive, ensuring all stretchable films are flat and aligned, squeezing out any air between the stretchable films and the core mold, with each stretchable film extending 50mm beyond the core mold at both ends; S3: According to the designed layup, lay carbon fiber prepreg prepared by hot-melt method, defining the length direction as 0°, and laying sequentially using the edge reference; This method for forming ply-laminated thin-walled irregular trusses is simple and efficient.

Description

Technical Field

[0001] This invention relates to the field of thin-walled truss forming technology, specifically to a method for forming layered thin-walled irregular trusses and a forming mold. Background Technology

[0002] Satellite structural components are framed with irregularly shaped thin-walled composite material stringers, which are mostly hollow thin-walled structures with embedded parts. The use of composite materials meets lightweight requirements, and the use of high-modulus carbon fiber, through reasonable layering design, can improve the stringer's stiffness and load-bearing capacity. For composite material stringer structures with irregular small cross-sections (side lengths not exceeding 30mm and lengths up to 3m), conventional metal molding and expanded rubber processes are insufficient to meet the demolding and straightness requirements of this type of product. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the problem that the composite stringers with irregular small cross sections in the prior art are difficult to meet the demolding and straightness requirements of this type of product, thereby providing a method for forming thin-walled irregular stringers and a forming mold.

[0004] To solve the above-mentioned technical problems, the present invention provides a method for forming a thin-walled irregular long stringer, comprising the following steps: S1: Check that the surfaces of the upper and lower molds are free of protrusions and burrs, and assemble and glue them using room temperature curing adhesive, aligning the edges of the upper and lower molds without misalignment to form a core mold; S2: Apply a release agent to the surface of the stretchable film at least 3 times, let it dry, and then use room temperature curing adhesive to attach it to the surface of the assembled core mold in a natural state, ensuring that all stretchable films are flat and joined together, squeezing out the air between the stretchable films and the core mold, with each stretchable film 50mm longer than the core mold at both ends; S3: According to the design layup, use carbon fiber prepreg prepared by hot melt method for layup, defining the length direction as 0°, and lay it sequentially with the edge reference; S4: Use a plastic plate to vertically press the corner positions of each layer to ensure that the prepreg is firmly attached and to squeeze out air bubbles in the bottom layer; S5: Lay the prepreg... The impregnation thickness is 0.08mm to 0.15mm, and 4 to 12 layers are used to prepare thin-walled irregular stringers; S6: Place the laid core mold on the bottom mold, and place the first and second pressing molds in sequence. Install the first and second locking parts in sequence and tighten them in sequence; S7: According to the hot melt prepreg model, heat seal at 80℃ to 100℃ for 30min to 60min until the gap between the bottom mold, the first pressing mold, and the second pressing mold is less than 0.1mm; S8: Curing is carried out according to the curing regime of the selected hot melt prepreg; S9: After curing, cool to room temperature, retain the bottom mold, the first pressing mold, and the second pressing mold, loosen the first and second locking parts, and slowly pull out the film in sequence; S10: After all the film has been removed, disassemble the bottom mold, the first pressing mold, and the second pressing mold, take out the product, and separate the composite material thin-walled stringer and the core mold.

[0005] Furthermore, the carbon fiber prepreg prepared by the hot-melt method can be laid in a cyclical manner at 0°, +45°, 90°, and -45°.

[0006] Furthermore, the prepared composite material thin-walled stringer has a length of 3m, a straightness of ≤1mm, and a cross-sectional dimensional accuracy of ±0.05mm.

[0007] Furthermore, the thickness of the stretchable film is ≤1mm, the temperature resistance is ≥260℃, and the elongation at break is ≥180%.

[0008] Furthermore, the pressure distance between the first locking member and the second locking member is 100mm to 300mm.

[0009] Furthermore, the prepreg is high-modulus carbon fiber M40J / cyanate prepreg.

[0010] The present invention also provides a forming mold used in the aforementioned method for forming thin-walled irregular long stringers, comprising: a core mold; a bottom mold disposed on the core mold and in contact with the core mold, the core mold having a contact portion and a connecting portion; a first pressing mold and a second pressing mold respectively in contact with the core mold, the first pressing mold and the second pressing mold also in contact with the connecting portion of the bottom mold; and a locking structure disposed on the bottom mold, the first pressing mold and the second pressing mold, the locking structure being used to lock the bottom mold, the first pressing mold and the second pressing mold.

[0011] Furthermore, the core mold includes an upper mold and a lower mold, the upper mold is disposed at one end of the lower mold, and the upper mold and one end of the lower mold are flush.

[0012] Furthermore, the bottom mold is L-shaped, the contact portion is located at the inflection point of the bottom mold, and the connecting portion is located close to the contact portion.

[0013] Furthermore, the contact portion is a stepped surface.

[0014] The technical solution of this invention has the following advantages:

[0015] 1. The method for forming thin-walled irregular long stringers provided by the present invention includes the following steps: S1: Check that the surfaces of the upper and lower molds are free of protruding burrs, and assemble and glue them using room temperature curing adhesive, aligning the edges of the upper and lower molds without misalignment to form a core mold; S2: Apply release agent to the surface of the stretchable film at least 3 times, let it dry, and use room temperature curing adhesive to attach it to the laying surface of the assembled core mold in a natural state, ensuring that all stretchable films are flat and joined together, squeezing out the air between the stretchable films and the core mold, with each stretchable film 50mm longer than the core mold at both ends; S3: According to the designed layup, use carbon fiber prepreg prepared by hot melt method for laying, defining the length direction as 0°, and using the edge reference for laying. S4: At the corners of each layer, use a plastic sheet to press vertically to ensure the prepreg adheres firmly and squeeze out air bubbles in the bottom layer; S5: The thickness of the prepreg is 0.08mm to 0.15mm, and 4 to 12 layers are used to prepare thin-walled irregular long stringers; S6: Place the laid core mold on the bottom mold, and then place the first and second pressing molds in sequence. Install the first and second locking parts in sequence and tighten them in sequence; S7: Depending on the type of hot melt prepreg, heat seal at 80℃ to 100℃ for 30 to 60 minutes until the gap between the bottom mold, the first pressing mold, and the second pressing mold is less than 0.1mm; S8: Cure according to the curing regime of the selected hot melt prepreg;

[0016] S9: After curing, cool to room temperature, retain the bottom mold, the first mold, and the second mold, loosen the first locking part and the second locking part, and slowly pull out the film in sequence; S10: After all the films have been removed, disassemble the bottom mold, the first mold, and the second mold, take out the product, and separate the composite material thin-walled stringer and the core mold.

[0017] The method for forming thin-walled irregular long stringers is simple and efficient, solving the problems of difficult demolding and poor product precision of composite materials with large aspect ratios. Moreover, the formed products have a smooth appearance and reliable internal quality.

[0018] 2. The forming mold used in the ply-lay thin-walled irregular stringer forming method provided by the present invention includes: a core mold; a bottom mold disposed on the core mold and in contact with the core mold, the core mold having a contact portion and a connecting portion; a first pressing mold and a second pressing mold respectively in contact with the core mold, and the first pressing mold and the second pressing mold also in contact with the connecting portion of the bottom mold; and a locking structure disposed on the bottom mold, the first pressing mold and the second pressing mold, the locking structure being used to lock the bottom mold, the first pressing mold and the second pressing mold.

[0019] By setting a bottom mold on the core mold, with the contact portion of the core mold and the bottom mold connected, and the connection portion of the first and second pressing molds connected to the bottom mold, the core mold is formed into a single unit using the bottom mold, the first pressing mold, and the second pressing mold. A stretchable film and prepreg are then laid on the core mold to produce thin-walled, irregularly shaped long stringers. This molding die simplifies the mold composition, has a simple form, and is easy to disassemble. The core film is prepared using the stretchable and variable cross-section characteristics of silicone sheets, improving production efficiency, reducing costs, and ensuring the internal quality stability of the product. It also solves the problems of poor molding accuracy and high demolding difficulty for composite materials with large aspect ratios, especially for small cross-sections, long dimensions, and thin walls. Furthermore, the molded product has a smooth appearance and reliable internal quality.

[0020] 3. The forming mold used in the ply-lay thin-walled irregular stringer forming method of the present invention has an L-shaped bottom mold, with the contact portion located at the inflection point of the bottom mold and the connecting portion located close to the contact portion. This achieves complete contact between the contact portion and the core mold, avoiding gaps. Simultaneously, the proximity of the connecting portion to the contact portion effectively ensures the connection stability of the first and second pressing molds and facilitates fixing the first and second pressing molds to the bottom mold.

[0021] 4. The forming mold used in the plywood thin-walled irregular stringer forming method of the present invention has multiple slots on the bottom mold, which are located on the outer edge of the bottom mold. These slots facilitate the accommodation of the first locking member and the second locking member, providing installation space for their installation.

[0022] The summary section is provided to present the chosen concepts in a simplified form, which will be further described in the detailed description below. The summary section is not intended to identify essential or necessary features of this disclosure, nor is it intended to limit the scope of this disclosure. Attached Figure Description

[0023] 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.

[0024] Figure 1 A schematic diagram of the structure of the plywood thin-walled irregular stringer forming mold provided by the present invention;

[0025] Figure 2 A schematic diagram of the core mold structure of the plywood thin-walled irregular stringer forming mold provided by the present invention.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1. Core mold; 2. Upper mold; 3. Lower mold; 4. Stretchable film; 5. Bottom mold; 6. First pressing mold; 7. Second pressing mold; 8. First locking element; 9. Second locking element; 10. Contact part; 11. Connecting part; 12. Groove. Detailed Implementation

[0028] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this disclosure. Therefore, the drawings and description are to be considered exemplary in nature and not restrictive.

[0029] In the description of this disclosure, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this disclosure. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0030] In the description of this disclosure, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joint" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, electrical connections, or connections that allow for communication; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0031] In this disclosure, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0032] The following disclosure provides numerous different embodiments or examples for implementing various structures of this disclosure. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this disclosure. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this disclosure, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0033] The preferred embodiments of this disclosure are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0034] Please see Figures 1 to 2As shown, this invention provides a method for forming a thin-walled irregular long stringer, comprising the following steps: S1: Check that the surfaces of the upper mold 2 and the lower mold 3 are free of protruding burrs, and assemble them with room temperature curing adhesive, aligning the edges of the upper mold 2 and the lower mold 3 to form a core mold 1; S2: Apply a release agent to the surface of the stretchable film 4 at least 3 times, let it dry, and then apply it in a natural state with room temperature curing adhesive to the surface of the assembled core mold 1, ensuring that all stretchable films 4 are flat and joined together, squeezing out the air between the stretchable films 4 and the core mold 1, with each stretchable film 4 being 50mm longer than the core mold 1 at both ends; S3: According to the designed layup, lay carbon fiber prepreg prepared by hot-melt method, defining the length direction as 0°, and laying it sequentially with the edge reference; S4: At the corner positions of each layer, use a plastic plate to vertically press to ensure that the prepreg is firmly attached and squeeze out the air bubbles in the bottom layer; S5: The thickness of the prepreg is 0. S6: Prepare thin-walled irregular-shaped stringers with 4 to 12 layers of 0.08mm to 0.15mm thickness; S7: Place the laid core mold 1 on the bottom mold 5, then place the first pressing mold 6 and the second pressing mold 7 in sequence, and install the first locking part 8 and the second locking part 9 in sequence, and tighten them in sequence; S8: According to the hot melt prepreg model, heat seal at 80℃ to 100℃ for 30min to 60min until the gap between the bottom mold 5, the first pressing mold 6, and the second pressing mold 7 is less than 0.1mm; S8: Curing is carried out according to the curing regime of the selected hot melt prepreg; S9: After curing, cool to room temperature, retain the bottom mold 5, the first pressing mold 6, and the second pressing mold 7, loosen the first locking part 8 and the second locking part 9, and slowly pull out the film in sequence; S10: After all the film has been removed, disassemble the bottom mold 5, the first pressing mold 6, and the second pressing mold 7, take out the product, and separate the composite material thin-walled stringer and the core mold 1.

[0035] The method for forming thin-walled irregular long stringers is simple and efficient, solving the problems of difficult demolding and poor product precision of composite materials with large aspect ratios. Moreover, the formed products have a smooth appearance and reliable internal quality.

[0036] In some optional embodiments, the carbon fiber prepreg prepared by the hot-melt method can be laid in a cyclical manner at 0°, +45°, 90°, and -45°. This method ensures the stability of the carbon fiber prepreg.

[0037] In some optional embodiments, the prepared composite thin-walled stringer has a length of 3m, a straightness of ≤1mm, and a cross-sectional dimensional accuracy of ±0.05mm.

[0038] In some optional embodiments, the thickness of the stretchable film 4 is ≤1mm, the temperature resistance is ≥260℃, and the elongation at break is ≥180%.

[0039] The pressure distance between the first locking member 8 and the second locking member 9 is 100mm to 300mm.

[0040] In this embodiment, the prepreg is high-modulus carbon fiber M40J / cyanate prepreg.

[0041] The specific forming method of this thin-walled irregular long stringer forming method; the tooling used includes a core mold 1, a stretchable sheet 4, a bottom mold 5, a first pressing mold 6, and a second pressing mold 7; the core mold 1 is made of a 2.5-meter-long glass fiber pultruded profile, the upper mold 2 has a cross-sectional dimension of 18mm×8mm, and the lower mold 3 has a cross-sectional dimension of 10mm×8mm; the surfaces of the upper mold 2 and the lower mold 3 are checked for burrs and are joined together with strong glue, with the edges aligned; the high-temperature resistant silicone sheet is cut into 19mm×1mm×2600mm and 20mm×1mm×2600mm pieces respectively. Two strips, 11mm×1mm×2600mm, 10mm×1mm×2600mm, and 8mm×1mm×2600mm, were coated with release agent three times and allowed to dry. Strong adhesive was then used to attach them sequentially and naturally to the surface of the assembled core mold 1, ensuring all strips were flat and aligned. Air between the strips and the core mold 1 was squeezed out, and each strip was 50mm longer than the core mold 1 at both ends. High-modulus carbon fiber M55J / epoxy prepreg was used, with a prepreg thickness of 0.1mm and a layup of 0° / +45° / -45° / 90° / +45° / -45°. Six layers are laid at a 5° angle to prepare a thin-walled composite material stringer with a wall thickness of 0.6mm. At the corners of each layer, plastic sheets are used for vertical compression to ensure the prepreg adheres firmly and to expel air bubbles from the bottom layer. The laid core mold 1 is placed on the bottom mold 5, followed by the first pressing mold 6 and the second pressing mold 7. The first locking element 8 and the second locking element 9 are then installed and tightened sequentially. The bottom mold 5, the first pressing mold 6, and the second pressing mold 7 are connected alternately using the first locking element 8 and the second locking element 9, with a pressure distance of 100mm in each direction. Depending on the type of hot-melt prepreg, it is heat-sealed at 100℃. 60 minutes, until the gaps between the bottom mold 5, the pressing mold, and the pressing mold are all less than 0.1 mm; cure according to the curing regime of the selected hot melt prepreg, curing regime 120℃ / 2h~170℃ / 4h; after curing, cool to room temperature, without disassembling the mold, loosen the first locking part 8 and the second locking part 9, and slowly pull out the film in sequence; after all the film has been removed, disassemble the mold, take out the product, separate the composite material thin-walled stringer and the core mold 1, and obtain a composite material stringer with a length of 2.5 meters, an L-shaped cross section, a cross section side length of 20 mm, and a wall thickness of 0.6 mm.

[0042] The L-shaped cross-section thin-walled composite material stringer is 3m long, with a straightness of ≤1mm and a cross-sectional dimensional accuracy of ±0.05mm.

[0043] A composite material stringer with a length of 3 meters, a T-shaped cross-section, a side length of 25 mm, and a wall thickness of 0.9 mm is prepared. The specific steps include: the tooling used includes a core mold 1, a stretchable sheet 4, a bottom mold 5, a first pressing mold 6, and a second pressing mold 7; the core mold 1 is made of a 3-meter-long long glass fiber pultruded profile; the upper mold 2 has a cross-sectional dimension of 9 mm × 8 mm, and the lower mold 3 has a cross-sectional dimension of 23 mm × 8 mm; the surfaces of the upper mold 2 and the lower mold 3 are checked for burrs and are joined together with strong adhesive, ensuring the edges are aligned; the high-temperature resistant silicone sheet is cut into 25 mm × 1 mm × 3 mm pieces respectively. Two strips of 100mm, 10mm×1mm×3100mm, and 11mm×1mm×3100mm, and four strips of 8mm×1mm×3100mm, are applied to the surface with three coats of release agent and allowed to dry. Strong adhesive is then used to attach them sequentially and naturally to the surface of the assembled core mold 1, ensuring all strips are flat and aligned. Air between the strips and the core mold 1 is squeezed out, and each strip is 50mm longer than the core mold 1 at both ends. High-modulus carbon fiber M40J / cyanate prepreg is used, with a prepreg thickness of 0.15mm and a layup of 0° / +45° / -45° / +45°. Six layers are laid at -45° / 90° to prepare a thin-walled composite material stringer with a wall thickness of 0.9mm. At the corners of each layer, plastic sheets are used for vertical compression to ensure the prepreg adheres firmly and to expel air bubbles from the bottom layer. The laid core mold 1 is placed on the bottom mold 5, followed by the first pressing mold 6 and the second pressing mold 7. The second locking element 9 and the first locking element 8 are then installed and tightened sequentially. The bottom mold 5, the first pressing mold 6, and the second pressing mold 7 are connected alternately using the first locking element 8 and the second locking element 9, with a pressure distance of 100mm in each direction. Based on the hot-melt prepreg model, at 10... Heat seal at 0℃ for 60 minutes until the gaps between the bottom mold 5, the pressing mold, and the pressing mold are all less than 0.1mm; cure according to the curing regime of the selected hot melt prepreg, the curing regime is 160℃ / 4h~190℃ / 4h; after curing, cool to room temperature, without disassembling the mold, loosen the first locking part 8 and the second locking part 9, and slowly pull out the film in sequence; after all the film has been removed, disassemble the mold, take out the product, separate the composite material thin-walled stringer and the core mold 1, and obtain a composite material stringer with a length of 3 meters, a T-shaped cross section, a cross section side length of 25mm, and a wall thickness of 0.9mm.

[0044] The T-shaped cross-section thin-walled composite material stringer is 3m long, with a straightness of ≤1mm and a cross-sectional dimensional accuracy of ±0.05mm.

[0045] The present invention also provides a forming mold for a method of forming a thin-walled irregular stringer, comprising: a core mold 1; a bottom mold 5 disposed on the core mold 1 and in contact with the core mold 1, the core mold 1 having a contact portion 10 and a connecting portion 11; a first pressing mold 6 and a second pressing mold 7 respectively in contact with the core mold 1, and the first pressing mold 6 and the second pressing mold 7 also in contact with the connecting portion 11 of the bottom mold 5; and a locking structure disposed on the bottom mold 5, the first pressing mold 6 and the second pressing mold 7, the locking structure being used to lock the bottom mold 5, the first pressing mold 6 and the second pressing mold 7.

[0046] By setting a bottom mold 5 on the core mold 1, and connecting the core mold 1 and the bottom mold 5 at the contact portion 10, and connecting the first pressing mold 6 and the second pressing mold 7 to the bottom mold 5 at the connection portion 11, the core mold 1 is formed into a single piece using the bottom mold 5, the first pressing mold 6, and the second pressing mold 7. A stretchable film 4 and prepreg are then laid on the core mold 1 to produce a thin-walled irregular-shaped long stringer. This molding die simplifies the mold composition, has a simple mold form, and is easy to disassemble. The core film is prepared using the stretchable and variable cross-section characteristics of silicone sheets, improving production efficiency, reducing costs, and ensuring the internal quality stability of the product. It also solves the problems of poor molding accuracy and high demolding difficulty of composite materials with large aspect ratios for small cross-sections, long dimensions, and thin walls. Furthermore, the molded product has a smooth appearance and reliable internal quality.

[0047] The mandrel 1 is made of composite pultruded profiles, aluminum strips, or steel strips. Mandrel 1 made of this material can effectively ensure the strength and rigidity of mandrel 1, thereby ensuring the service life of mandrel 1, allowing it to be reused and reducing processing costs.

[0048] In some optional embodiments, the core mold 1 includes an upper mold 2 and a lower mold 3, with the upper mold 2 disposed at one end of the lower mold 3, and the upper mold 2 and one end of the lower mold 3 being flush. That is, the core mold 1 has an L-shaped structure.

[0049] In some optional embodiments, the bottom mold 5 is L-shaped, the contact portion 10 is located at the inflection point of the bottom mold 5, and the connecting portion 11 is located close to the contact portion 10. This achieves complete contact between the contact portion 10 and the core mold 1, avoiding gaps. At the same time, the proximity of the connecting portion 11 to the contact portion 10 effectively ensures the connection stability of the first pressing mold 6 and the second pressing mold 7, and facilitates fixing the first pressing mold 6 and the second pressing mold 7 to the bottom mold 5.

[0050] In this embodiment, the contact portion 10 is a stepped surface, which can effectively and completely contact the L-shaped core mold 1, avoiding gaps.

[0051] In some alternative embodiments, the connecting portion 11 is an L-shaped contact surface provided on the bottom mold 5. The connecting portion 11 can be effectively connected to the first mold 6 and the second mold 7.

[0052] Meanwhile, multiple locking holes are provided on the bottom mold 5. The locking structure includes a first locking member 8 and a second locking member 9. The first locking member 8 passes through the locking holes to connect the bottom mold 5 and the first pressing mold 6, and the second locking member 9 passes through the locking holes to connect the bottom mold 5 and the second pressing mold 7. That is, the first locking member 8 is used to connect the bottom mold 5 and the first pressing mold 6, and the second locking member 9 is used to connect the bottom mold 5 and the second pressing mold 7.

[0053] In some optional embodiments, the bottom mold 5 is provided with a plurality of slots 12, which are located on the outer edge of the bottom mold 5. The slots 12 are provided to facilitate the accommodation of the first locking member 8 and the second locking member 9, and provide installation space for the installation of the first locking member 8 and the second locking member 9.

[0054] In this embodiment, the first locking member 8 is a screw, and the second locking member 9 is a bolt.

[0055] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for forming a ply-laminated thin-walled irregular long stringer, characterized in that, Includes the following steps: S1: Check that there are no protruding burrs on the surface of the upper mold (2) and the lower mold (3). Assemble and glue them with room temperature curing adhesive. Align the edges of the upper mold (2) and the lower mold (3) and assemble them into a core mold (1) without misalignment. S2: Apply release agent to the surface of the stretchable film (4) at least 3 times, let it dry, and use room temperature curing adhesive to attach it to the surface of the assembled core mold (1) in a natural state. All stretchable films (4) are flat and joined together, and the air between the stretchable film (4) and the core mold (1) is squeezed out. Both ends of each stretchable film (4) are 50mm longer than the core mold (1). S3: According to the design layup, carbon fiber prepreg prepared by hot melt method is laid, the length direction is defined as 0°, and the layup is carried out sequentially with the edge reference; S4: Use a plastic sheet to press the corners of each layer vertically to ensure the prepreg adheres firmly and squeeze out air bubbles in the bottom layer; S5: The thickness of the prepreg is 0.08mm to 0.15mm, and 4 to 12 layers are used to prepare thin-walled irregular long stringers; S6: Place the laid core mold (1) on the bottom mold (5), place the first pressing mold (6) and the second pressing mold (7) in sequence, install the first locking part (8) and the second locking part (9) in sequence, and tighten them in sequence; S7: According to the hot melt prepreg model, heat seal at 80℃~100℃ for 30min~60min until the gap between the bottom mold (5), the first mold (6), and the second mold (7) is less than 0.1mm; S8: Curing shall be carried out according to the curing regime of the selected hot melt prepreg; S9: After curing, cool to room temperature, retain the bottom mold (5), the first mold (6), and the second mold (7), loosen the first locking part (8) and the second locking part (9), and slowly pull out the film in sequence; S10: After all the films have been removed, disassemble the bottom mold (5), the first mold (6), and the second mold (7), remove the product, and separate the composite material thin-walled stringer and the core mold (1).

2. The method for forming thin-walled irregular long stringers according to claim 1, characterized in that, Carbon fiber prepreg prepared by hot-melt method can be laid in a cyclical manner at 0°, +45°, 90°, and -45°.

3. The method for forming thin-walled irregular long stringers according to claim 2, characterized in that, The prepared composite material thin-walled stringer has a length of 3m, a straightness of ≤1mm, and a cross-sectional dimensional accuracy of ±0.05mm.

4. The method for forming thin-walled irregular long stringers according to any one of claims 1-3, characterized in that, The thickness of the stretchable film (4) is ≤1mm, the temperature resistance is ≥260℃, and the elongation at break is ≥180%.

5. The method for forming thin-walled irregular long stringers according to claim 4, characterized in that, The pressure distance between the first locking element (8) and the second locking element (9) is 100mm to 300mm.

6. The method for forming thin-walled irregular long stringers according to claim 5, characterized in that, The prepreg is high-modulus carbon fiber M40J / cyanate prepreg.

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