Carbon fiber composite material T-shaped beam structure and autoclave forming mold and method

Abstract

The invention discloses a carbon fiber composite material T-shaped beam structure and an autoclave forming mold and forming method. The carbon fiber composite material T-shaped beam structure comprises a first structure layer, a second structure layer, a third structure layer and a filling structure, and long-term use of the T-shaped beam structure under various complex working conditions is met through reasonable layering design; the autoclave forming mold comprises a mold body and a side sliding block, the section of the mold body is in an L shape, the mold body is provided with a material piece paving face and a mold closing face, the side sliding block is provided with a paving face matched with a second structural layer, and after the mold body and the side sliding block are closed, a double-face mold pressing area of a flange corresponding to the horizontal section of the second structural layer is formed. And an autoclave forming process is combined, and a mode of integral vacuum bag pressing and local double-sided mold pressing is adopted, so that material sheet paving is simple and easy to operate, and a formed product is low in porosity.

Description

Technical Field

[0001] The invention relates to the field of carbon fiber composite materials, and in particular to a carbon fiber composite material T-beam structure and an autoclave forming mold and method. Background Art

[0002] Carbon fiber composite materials have the advantages of high strength, high modulus, and corrosion resistance, and have been widely used in aerospace, automobile, rail transportation and other fields. In recent years, with the rapid development of the low-altitude economy, carbon fiber composite materials have gradually replaced aluminum alloys and become the most used material in various aircraft due to their light weight and high strength.

[0003] The carbon fiber composite T-beam structure is a typical structural component that resists bending on aircraft. The existing manufacturing processes of carbon fiber composite T-beam structures are: (1) three-dimensional weaving molding: through the carbon fiber three-dimensional weaving technology, the fibers are woven into a T-shaped preform with a three-dimensional structure, the preform is placed in a mold, and then the resin is poured into the carbon fiber preform to impregnate the carbon fiber preform, and the final product is obtained after curing. The disadvantages of this process are that the weaving equipment is expensive, the production efficiency is low, and the product has a high resin content, high porosity, and poor overall quality. (2) pultrusion molding: the carbon fiber tow is unfolded, the carbon fiber tow passes through the resin tank, the resin impregnates the carbon fiber, and the impregnated carbon fiber passes through a mold with a T-shaped cross-section. The mold is heated to solidify the resin, and the solidified product is removed by a traction device, and then cut to a fixed length to obtain the product. This process has low cost and high production efficiency, but due to process limitations, it can only produce unidirectional carbon fiber composites (usually in the 0° direction). Therefore, the strength in the direction perpendicular to the fiber is poor, and it cannot be used in a stress environment with complex working conditions. (3) Autoclave process: one is to pre-fabricate a T-beam structure made of metal material, then lay carbon fiber prepreg on the surface of the metal T-beam structure, and then evacuate and seal it with a vacuum bag, and then put it into an autoclave for heating and pressurization to cure and form, and finally obtain a T-beam structure with an inner core made of metal material and an outer layer made of carbon fiber composite material. This process is simple to operate, but due to the presence of the metal inner core, the weight of the product is still very high and cannot meet the strict weight requirements of the aviation field for products; another existing autoclave process is to prepare a full carbon fiber composite material T-beam structure by modularizing the mold so that the mold has the same T-shaped cavity as the T-beam structure after the mold is closed. For example, CN104552667A discloses a T-beam structure composite material autoclave forming mold. Although this method can realize the preparation of a full carbon fiber composite material T-beam structure, it is troublesome to lay the sheet and difficult to assemble the mold. In addition, the product is double-sided molded, and there will be a problem that the gas in the molded area cannot be discharged smoothly, the product porosity is high, and the overall performance is affected. Summary of the invention

[0004] In order to make up for the deficiencies in the prior art, the present invention provides a carbon fiber T-beam structure and an autoclave forming mold and method thereof, which are used to solve the problems of high porosity, high weight, low production efficiency, etc. of products in the prior art.

[0005] In order to achieve the above-mentioned object, the present invention provides a carbon fiber composite material T-beam structure in a first aspect, comprising a first structural layer, a second structural layer, a third structural layer and a filling structure; The first structural layer is horizontally arranged along the flange; The second structural layer is arranged in an L shape, including a horizontal section compounded with the first structural layer, and a vertical section perpendicular to the first structural layer; The third structural layer is arranged in an inverted L shape, including a horizontal segment compounded with the first structural layer, and a vertical segment perpendicular to the first structural layer; The horizontal section of the second structural layer, the horizontal section of the third structural layer and the first structural layer together form the flange of the T-beam structure; the vertical section of the first structural layer and the vertical section of the second structural layer together form the web of the T-beam structure; The filling structure is arranged in a triangular hollow area formed by the first structural layer, the second structural layer and the third structural layer.

[0006] In another embodiment, the T-beam structure is composited with carbon fiber unidirectional prepreg, and the ply angles of the carbon fiber unidirectional prepreg in the first structural layer are set at 0° / ±45° / 0° / 90°; the ply angles of the carbon fiber unidirectional prepreg in the second structural layer and the third structural layer are set at 90° / 0° / ±45° / 0°; and the filling structure is rolled from carbon fiber unidirectional prepreg.

[0007] In a second aspect, the present invention provides an autoclave forming die for a carbon fiber composite material T-beam structure, comprising a die body and a side slide block; The cross section of the mold body is L-shaped, including a sheet paving surface and a mold joining surface; The side sliding block has a paving surface matched with the second structural layer; After the mold body and the side slide block are molded together, a double-sided mold area and a single-sided mold area are formed, and the double-sided mold area provides molding for the flange area of ​​the horizontal section of the second structural layer.

[0008] In another embodiment, a sealing structure is further provided on the sheet paving surface of the mold body on the side close to the mold mating surface.

[0009] In another embodiment, the sheet paving surface of the mold body is further provided with grid-shaped air guide grooves, and exhaust holes are provided at the cross-intersection positions of the air guide grooves along the thickness direction of the mold.

[0010] In a third aspect, a method for hot-pressing a carbon fiber composite material T-beam structure is provided, comprising: S1, sheet cutting; S2. Paving of sheet materials: S21, firstly laying the sheet of the first structural layer on the mold body, and packing the sheet to perform vacuuming, and then unpacking the sheet to form a preform of the first structural layer; S22, secondly, laying the sheet of the second structural layer on the side slider, and packing the bag to perform vacuuming, and after unpacking the bag, a preform of the second structural layer is formed; preferably, before laying the sheet of the second structural layer, a foaming material layer is further provided on the laying surface of the side slider corresponding to the horizontal section of the preform of the second structural layer; and the foaming material layer is wrapped with a semipermeable membrane; S23, mold closing: assembling and closing the mold body on which the preform of the first structural layer is laid and the side slide block on which the preform of the second structural layer is laid, and then vacuuming and compacting the whole bag; S24, laying the filling structure; S25, continuing to lay the sheet of the third structural layer on the basis of the first structural layer and the second structural layer to form a preform of the T-beam structure; S26, bagging: laying release cloth, isolation film, breathable felt and other auxiliary materials on the surface of the preform of the T-beam structure in sequence, sealing the entire mold with a vacuum bag and evacuating the vacuum; S3, placing the entire mold into an autoclave, heating and pressurizing for curing.

[0011] Compared with the prior art, the present invention has at least the following beneficial effects: (1) The present invention provides a carbon fiber composite material T-beam structure, which can meet the stress strength of the T-beam structure in different directions through overall layer design; (2) The present invention optimizes the mold by designing the mold into a mold body and a side slide block. On the other hand, the process is optimized by adopting an autoclave process combining overall vacuum bag pressing and local double-sided molding, thereby solving the difficulties in laying the T-beam structure sheet and assembling the mold. The present invention can adapt to the production of T-beam structure products with complex shapes, multiple thickness changes, and complex stress conditions, and solves the quality defect of high porosity in the traditional double-sided molding. (3) The design of the air guide grooves and exhaust holes on the mold allows the gas trapped inside the material to escape along the air guide grooves and exhaust holes on one side of the mold surface during the vacuuming process of the preform, which is beneficial to pre-compaction and can also improve the exhaust during the curing process, so that the final product has higher density and lower porosity. The air guide grooves can also form a cross-shaped pattern structure on the surface of the product, roughening the surface of the product, increasing the surface friction, and increasing the bonding and assembly strength of the subsequent product with other components. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Attached Figure 1 This is a schematic diagram of the T-beam structure of the present invention; Attached Figure 2 Schematic diagram of laying T-beam structure sheets in the mold.

[0013] Among them: 1-first structural layer; 2-second structural layer; 3-third structural layer; 4-filling structure; 4-carbon fiber round rod; 5-semipermeable membrane; 6-foam film; 7-sealing structure; 8-side slider; 9-mold body. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the drawings in the embodiments of the present invention and the technical solution of the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "center", "upper", "lower", "inner", "outer", etc. are based on the directions or positional relationships 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 direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0016] See also Figure 1-2 A carbon fiber composite material T-beam structure shown includes a first structural layer 1, a second structural layer 2, a third structural layer 3 and a filling structure 4; The first structural layer 1 is arranged horizontally along the flange; The second structural layer 2 is arranged in an L-phase, including a horizontal segment compounded with the first structural layer 1, and a vertical segment perpendicular to the first structural layer 1; The third structural layer 3 is arranged in an inverted L shape, including a horizontal segment compounded with the first structural layer 1, and a vertical segment perpendicular to the first structural layer 1; The horizontal section of the second structural layer 2, the horizontal section of the third structural layer 3 and the first structural layer 1 form a flange of a T-beam structure; the vertical section of the first structural layer 1 and the vertical section of the second structural layer 2 form a web of a T-beam structure; The filling structure 4 is arranged in a triangular hollow area formed by the first structure layer 1 , the second structure layer 2 , and the third structure layer 3 .

[0017] The T-beam structure as a whole is composited with carbon fiber prepreg. Taking the length direction of the T-beam structure as the 0 degree direction, the laying angles of the carbon fiber unidirectional prepreg layer in the first structural layer 1 are 0°, ±45°, 0°, and 90°; the laying angles of the carbon fiber unidirectional prepreg in the second structural layer 2 and the third structural layer 3 are 90°, 0°, ±45°, and 0°; the filling structure 4 is rolled with carbon fiber unidirectional prepreg.

[0018] The flange is designed with a dropped layer from both sides toward the web, and the carbon fiber unidirectional prepreg is offset inward by 10 cm layer by layer to form a T-beam structure with a thick middle and thin edges and varying thickness.

[0019] Combination Figure 2 As shown, a carbon fiber autoclave forming mold comprises a mold body 9 and a side slider 8; The mold body 9 has an L-shaped cross-section, including a material paving surface and a mold clamping surface, and the side slider 9 has a paving surface adapted to the second structural layer 2; after the mold body 9 and the side slider 8 are molded together, double-sided molding is provided for the flange of the horizontal section of the corresponding second structural layer 2, and then after the vacuum bag is evacuated as a whole, the overall pressurization of the T-beam structure is achieved; a sealing structure 7 is also provided on the material paving surface of the mold body 9 close to the mold clamping surface, specifically, a sealing groove is provided, and a sealing strip is filled in the groove.

[0020] Furthermore, the paving surface of the mold sheet is provided with grid-shaped air guide grooves, and exhaust holes are provided at the cross positions of the air guide grooves along the thickness direction of the mold, which can facilitate the escape of gas during paving, pre-compacting and subsequent vacuum curing.

[0021] A carbon fiber composite material T-beam structure autoclave forming method, comprising: S1. Cutting of sheets: Cut the prepreg according to the structural dimensions of the T-beam and number them; S2, sheet laying; S21, first lay the carbon fiber prepreg sheet of the first structural layer 1 on the mold body 9 according to the laying angle, and then seal it with a vacuum bag film and vacuum the sheet to compact it, and remove the vacuum bag film to form a first structural layer preform; vacuum degree> 920mba, compaction time> 15min; S22, secondly, the sheet of the second structural layer 2 is laid on the side slider 8, and then the sheet is vacuumed and compacted after being sealed with a vacuum bag film, and a second structural layer preform is formed after the vacuum bag film is removed; the vacuum degree is greater than 920mba, and the compaction time is greater than 15min; a foaming material layer is also provided between the horizontal section of the second structural layer preform and the side slider 8, specifically an epoxy foaming film, and the width is adapted to the width of the horizontal section of the second structural layer; the foaming film is wrapped with a semipermeable membrane; S23, mold closing: assembling the mold body with the preformed body of the first structural layer laid thereon and the side slide block with the preformed body of the second structural layer laid thereon, and vacuuming and compacting the whole bag; S24, laying the filling structure; using a carbon fiber unidirectional prepreg of a certain width, rolling it into a rod-shaped filling structure adapted to the length of the T-beam structure, and placing it at the R angle position where the first structural layer and the second structural layer cooperate; the fiber direction of the carbon fiber unidirectional prepreg of the filling structure is the same as the length direction of the T-beam structure; S25, laying the sheet of the third structural layer along the first structural layer and the second structural layer on the assembled mold as a whole, so as to form a preform of the T-beam structure; S26, bagging and vacuuming: laying release cloth, isolation film, breathable felt and other auxiliary materials on the surface of the T-beam structure preform in sequence, sealing the entire mold with a vacuum bag and vacuuming; S3. Place the sealed mold as a whole into the autoclave, heat and pressurize for curing. Specifically, first heat from room temperature to 80°C, then keep warm for 30 minutes, then heat from 80°C to 150°C again, then keep warm for 120 minutes, then cool from 150°C to 60°C, and then demould; heating rate: 2-5°C / min; pressurization method: pressurize from 0 to 0.7Mpa, then maintain pressure until the product is released before demoulding.

[0022] Obviously, the above embodiments are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here, and the obvious changes and modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A carbon fiber composite T-beam structure, characterized in that: It includes a first structural layer, a second structural layer, a third structural layer and a filling structure; The first structural layer is arranged along the horizontal direction of the flange; The second structural layer is arranged in an L shape, including a horizontal section compounded with the first structural layer, and a vertical section perpendicular to the first structural layer; The third structural layer is arranged in an inverted L shape, including a horizontal segment compounded with the first structural layer, and a vertical segment perpendicular to the first structural layer; The horizontal section of the second structural layer, the horizontal section of the third structural layer and the first structural layer together form the flange of the T-beam structure; the vertical section of the first structural layer and the second structural layer together form the web of the T-beam structure; The filling structure is arranged in a triangular hollow area formed by the first structural layer, the second structural layer and the third structural layer.

2. A carbon fiber composite material T-beam structure according to claim 1, characterized in that: The whole structure is composited with carbon fiber unidirectional prepreg; the ply angles of the carbon fiber unidirectional prepreg layer in the first structural layer are set at 0° / ±45° / 0° / 90°; the ply angles of the carbon fiber unidirectional prepreg in the second structural layer and the third structural layer are set at 90° / 0° / ±45° / 0°; the filling structure is rolled with carbon fiber unidirectional prepreg.

3. A carbon fiber composite material T-beam structure autoclave forming mold, characterized in that: Used to form the T-beam structure described in any one of claims 1-2, comprising a mold body and a side slide block; The mold body has an L-shaped cross section, including a sheet paving surface and a mold joining surface; The side sliding block has a paving surface matched with the second structural layer; After the mold body and the side slide block are molded together, double-sided molding of the flange corresponding to the horizontal section of the second structural layer is provided.

4. The carbon fiber composite material T-beam structure autoclave forming mold according to claim 3, characterized in that: A sealing structure is also provided on the sheet paving surface of the mold body on the side close to the mold mating surface.

5. The carbon fiber composite material T-beam structure autoclave forming mold according to claim 3, characterized in that: The sheet paving surface of the mold is also provided with grid-shaped air guide grooves, and exhaust holes are provided at the cross-intersection positions of the air guide grooves along the thickness direction of the mold.

6. A carbon fiber composite material T-beam structure autoclave forming method, characterized in that: Based on any one of claims 3-5, the molding die comprises the steps of: S1, sheet cutting; S2. Paving of sheet materials: S21, firstly laying the sheet of the first structural layer on the mold body, and packing the sheet to perform vacuuming, and then unpacking the sheet to form a preform of the first structural layer; S22, secondly, laying the sheet of the second structural layer on the side slider, and packing the sheet to perform vacuuming, and unpacking the sheet to form a preform of the second structural layer; S23, mold closing: assembling the mold body with the preformed body of the first structural layer and the slider with the preformed body of the second structural layer, and vacuuming and compacting the whole bag; S24, laying the filling structure; S25, laying the sheet of the third structural layer on the assembled mold body and the side slide block to form a preform of the T-beam structure; S26, bagging: laying release cloth, isolation film, breathable felt and other auxiliary materials on the surface of the T-beam structure preform in sequence, sealing the entire mold with a vacuum belt and evacuating the vacuum; S3, placing the entire mold into an autoclave, heating and pressurizing for curing.

7. The method for forming a carbon fiber composite material T-beam structure by an autoclave according to claim 6, characterized in that: In the step S22, before paving the sheet of the second structural layer, it also includes setting a foam material structural layer on the paving surface of the side slider corresponding to the horizontal section of the second structural layer preform; the foam material structural layer is wrapped with a semipermeable membrane.

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