Forming method of heat-proof layer with special-shaped structure

Abstract

The invention discloses a special-shaped structure heat-proof layer forming method, and belongs to the technical field of composite material forming. The forming method comprises the following steps: preparing a first prepreg, cutting the first prepreg according to a first angle to obtain an inner-layer prepreg block, and cutting the first prepreg according to a second angle to obtain an outer-layer prepreg block; the inner-layer prepreg blocks are laid on the force bearing body layer by layer in a warp and weft staggered mode, the outer-layer prepreg blocks are laid on the inner-layer prepreg blocks layer by layer in a warp and weft staggered mode, and a large-area heat-proof layer laying layer set is obtained; preparing to obtain an edge heat-proof layer blank body; cutting off a thin-wall area on the edge heat-proof layer blank body; placing the edge heat-proof layer blank body after the thin-wall area is cut off on a mould pressing tool, laying a second prepreg in the area of the mould pressing tool corresponding to the cut-off part, and pre-pressing to obtain an edge heat-proof layer composite blank body; embedding the edge heat-proof layer composite blank body into the prepreg laying layer group to obtain a heat-proof layer blank body with a special-shaped structure; and performing curing treatment on the heat-proof layer blank with the special-shaped structure to obtain the heat-proof layer with the special-shaped structure.

Description

Technical Field

[0001] The present application belongs to the technical field of composite material molding, and in particular relates to a molding method for a special-shaped structure heat-resistant layer. Background Art

[0002] Most traditional aircraft have regular cylindrical or conical structures. In order to meet aerodynamic requirements, high-speed aircraft are designed with special-shaped structures to maintain a high lift-to-drag ratio. Since their flight environment needs to go through thin gas layers and dense atmosphere, aerodynamic heating is extremely harsh. In order to better control accuracy and flight distance, their thermal protection structure is required to be resistant to high temperatures, lightweight, anti-ablation, and high-strength.

[0003] Compared with traditional aircraft structures, the surface of special-shaped aircraft is more complex, and the heat protection layer is very easy to deform after forming. In the process of combining with the load-bearing shell, it brings problems such as difficulty in dimensional control and inaccurate positioning. Summary of the invention

[0004] The present application aims to at least to some extent solve the technical problem that the deformation of the heat-resistant layer of a special-shaped structure is large after being formed. To this end, the present application provides a method for forming a heat-resistant layer of a special-shaped structure.

[0005] The present application provides a method for forming a heat-resistant layer with a special-shaped structure, comprising:

[0006] Preparing a first prepreg and cutting the first prepreg at a first angle to obtain an inner prepreg block, and cutting the first prepreg at a second angle to obtain an outer prepreg block;

[0007] The inner layer prepreg blocks are laid layer by layer on the load-bearing body in a warp and weft staggered manner, and the outer layer prepreg blocks are laid layer by layer on the inner layer prepreg blocks in a warp and weft staggered manner to obtain a large-area heat-proof layer laying layer group;

[0008] Prepare the edge heat protection layer embryo;

[0009] Cutting off the thin wall area on the edge heat protection layer embryo;

[0010] Placing the edge heat protection layer embryo body after cutting off the thin-walled area on a molding tool, and laying a second prepreg in the area of ​​the molding tool corresponding to the cut-off part and pre-pressing it to obtain an edge heat protection layer composite embryo body;

[0011] The composite embryo of the edge heat protection layer is embedded in the prepreg laying layer group to obtain a special-shaped structure heat protection layer embryo;

[0012] The embryo of the special-shaped heat-proof layer is cured to obtain the special-shaped heat-proof layer.

[0013] In some embodiments, the curing treatment is performed by step temperature, and when the curing temperature is 80° C. to 100° C., the temperature is kept for 6 h to 8 h, and when the curing temperature is 110° C. to 130° C., the temperature is kept for 3 h to 4 h.

[0014] In some embodiments, the thickness of the first prepreg is 0.5 mm to 2.5 mm, the first prepreg is a 2.5D woven fabric prepreg, the fibers of the first prepreg are a mixed fabric of quartz fibers and organic fibers, and the resin of the first prepreg is phenolic resin.

[0015] In some embodiments, the thickness of the second prepreg is 0.5 mm to 1 mm, the second prepreg is a 2.5D woven fabric prepreg, the fibers of the second prepreg are a mixed fabric of quartz fibers and organic fibers, and the resin of the second prepreg is phenolic resin.

[0016] In some embodiments, the edge heat protection layer embryo is prepared by a molding process.

[0017] In some embodiments, the prepreg material of the edge heat protection layer embryo body includes mixed fibers, air-energy fillers and resins, the mixed fibers include two or three of quartz fibers, carbon fibers or high-silica fibers, the air-energy fillers are one or two of hollow microbeads or boron carbides, and the resin includes one or more of barium phenolic formaldehyde, aminophenolic formaldehyde or modified phenolic formaldehyde.

[0018] In some embodiments, the first angle is 45° and the second angle is 90°.

[0019] In some embodiments, each layer of the large-area heat protection layer laying layer group is formed by splicing 4 to 6 inner layer prepreg blocks, or is formed by splicing 2 to 3 outer layer prepreg blocks.

[0020] In some embodiments, the splicing positions of two adjacent inner prepreg blocks in the same layer are connected by quartz stitching lines, and the splicing positions of two adjacent outer prepreg blocks in the same layer are also connected by quartz stitching lines.

[0021] In some embodiments, the thin-walled region is a region with a thickness less than 5 mm.

[0022] The present invention has at least the following beneficial effects:

[0023] The method for forming a special-shaped structure heat-proof layer of the present invention lays the inner prepreg block and the outer prepreg block in a warp-weft staggered manner, so that the first prepreg can maintain the same warp and weft direction during the laying process, reducing the difference in various anisotropies. The inner prepreg block and the outer prepreg block are cut at different angles to ensure the conformability and ductility of the inner prepreg block and the outer prepreg block during laying, so that the first prepreg can better fit the outer surface of the load-bearing body. The present invention first prepares an edge heat protection layer embryo, then cuts off the thin-walled area of ​​the edge heat protection layer embryo, and then fills the cut-off area by laying and pre-pressing the second prepreg to obtain an edge heat protection layer composite embryo, and then buries the edge heat protection layer composite embryo into the prepreg laying layer group to obtain a heat protection layer embryo, and then cures the heat protection layer embryo to obtain a special-shaped heat protection layer. The present invention cuts off the thin-walled area, and uses the second prepreg to form a thin-walled area by a transitional filling layer, so that the thin-walled area and the large-area heat protection layer area of ​​the first prepreg layer are co-cured and formed, thereby reducing the deformation of the thin-walled area. Compared with the special-shaped heat protection layer processed by the prior art, the special-shaped heat protection layer prepared by the special-shaped heat protection layer forming method of the present invention can reduce the deformation of more than 60%, and the special-shaped heat protection layer forming method of the present invention can well reduce the deformation of the special-shaped heat protection layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 A schematic cross-sectional view of the first end and the second end of the special-shaped heat protection layer in one or more embodiments of the present application is shown.

[0026] Figure 2 A schematic diagram of the structure of a special-shaped heat protection layer in one or more embodiments of the present application is shown.

[0027] Figure 3 A flow chart of a method for forming a heat-resistant layer with a special-shaped structure in one or more embodiments of the present application is shown.

[0028] Figure 4 A schematic diagram of cutting an inner layer prepreg block in one or more embodiments of the present application is shown.

[0029] Figure 5 A schematic diagram of cutting an outer layer prepreg block in one or more embodiments of the present application is shown.

[0030] Figure 6A schematic diagram is shown of cutting off the thin-walled area on the edge heat protection layer embryo body and then laying and pre-pressing the second prepreg in one or more embodiments of the present application.

[0031] Reference numerals: 1 - first end, 2 - second end, 1.1 - upper part, 1.2 - lower part, 1.21 - first straight side, 1.22 - second straight side, 1.23 - curved side. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] It should be noted that all directional indications in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between various components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0034] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0036] Most traditional aircraft have regular cylindrical or conical structures. In order to meet aerodynamic requirements, high-speed aircraft are designed with special-shaped structures to maintain a high lift-to-drag ratio. Since their flight environment needs to go through thin gas layers and dense atmosphere, aerodynamic heating is extremely harsh. In order to better control accuracy and flight distance, their thermal protection structure is required to be resistant to high temperatures, lightweight, anti-ablation, and high-strength.

[0037] Compared with traditional aircraft structures, the surface of special-shaped aircraft is more complicated. In addition, due to the anisotropic characteristics of composite materials, combined with thin walls, multiple interfaces and other structures, the heat protection layer is very easy to deform after forming. In the process of combining with the load-bearing shell, it brings problems such as difficulty in dimensional control and inaccurate positioning. At the same time, large internal stress is formed between the heat protection layer and the load-bearing shell, which poses a great risk to the stability of the structure during the use of the aircraft.

[0038] In the related art, the special-shaped heat-proof layer has the technical problem of large deformation after forming. The embodiment of the present application provides a method for forming a special-shaped heat-proof layer, which can at least solve the technical problem of large deformation after forming a special-shaped heat-proof layer to a certain extent.

[0039] In some embodiments of the present application, the following special-shaped heat-proof layer is formed by the special-shaped heat-proof layer forming method:

[0040] like Figure 1 and Figure 2 As shown, the special-shaped heat-proof layer comprises a first end 1 and a second end 2 opposite to each other, and the first end 1 and the second end 2 are connected by a variable cone surface. The cross section of the second end 2 of the special-shaped heat-proof layer is circular, the cross section of the upper part 1.1 of the first end 1 of the special-shaped heat-proof layer is in the shape of a Chinese character "J", and the cross section of the lower part 1.2 of the first end 1 comprises a first straight edge 1.21, a second straight edge 1.22 and a curved edge 1.23, one end of the first straight edge 1.21 and one end of the second straight edge 1.22 are respectively connected to the two ends of the Chinese character "J", and the first straight edge 1.21 and the second straight edge 1.22 are parallel to the center line of the Chinese character "J", and the other end of the first straight edge 1.21 and the other end of the second straight edge 1.22 are connected by the curved edge 1.23, and the curved edge 1.23 is arc-shaped, and the arc is arranged away from the middle of the Chinese character "J".

[0041] like Figure 2 As shown, the special-shaped heat protection layer consists of two edge heat protection layers ( Figure 2 The large-area heat protection part is composed of a large-area heat protection layer (a middle dotted line area) and a large-area heat protection layer (all areas except the edge heat protection layer are large-area heat protection layers). The thickness of the large-area heat protection part is relatively uniform, and the edge heat protection layer is arranged close to the first end. The thickness of the edge heat protection layer is uneven, thick at one end and thin at the other end. The maximum thickness of the edge heat protection layer is 40mm to 60mm, and the minimum thickness is only 0.5mm. The special-shaped heat protection layer has the characteristics of small acute angles, R angles, and bevels.

[0042] The special-shaped heat-proof layer is a thin-walled special-shaped structure with poor rigidity. The thickness of the special-shaped heat-proof layer is not uniform at different places. In the multi-interface structure, the rigidity of each part is inconsistent. After being formed by the existing method, there is a large deformation. At the same time, due to the large size of the special-shaped heat-proof layer, the profile of the special-shaped heat-proof layer changes in a complex manner, and a single measure cannot control the deformation problem. Experiments have proved that compared with processing the special-shaped heat-proof layer by the existing technology, the deformation of the special-shaped heat-proof layer prepared by the special-shaped heat-proof layer forming method of the present invention can be reduced by more than 60%. The special-shaped heat-proof layer forming method of the present invention can well reduce the deformation of the special-shaped heat-proof layer.

[0043] It should be noted that the method for forming a special-shaped heat-proof layer provided by the present invention can be used to form the above-mentioned special-shaped heat-proof layer, and of course it can also be used to form other special-shaped heat-proof layers, for example, the method can be used to form the special-shaped heat-proof layer disclosed in Patent Publication No. CN116372506A. Figure 1 The disclosed special-shaped structure may also be the one disclosed in patent publication number CN111196048B. Figure 2 The disclosed special-shaped structures and the like are not limited in this application.

[0044] The following is a detailed description of the method for forming a special-shaped heat-resistant layer of the present application:

[0045] like Figure 3 As shown, the method for forming a special-shaped structure heat-proof layer includes steps S100, S200, S300, S400, S500, S600 and S700.

[0046] S100, such as Figure 4 and Figure 5 As shown, a first prepreg is prepared and cut at a first angle to obtain an inner prepreg block, and the first prepreg is cut at a second angle to obtain an outer prepreg block.

[0047] The purpose of this step is to cut the first prepreg into multiple inner prepreg blocks for laying out to form the inner layer of the special-shaped structure heat protection layer, and cut it into multiple outer prepreg blocks for laying out to form the outer layer of the special-shaped structure heat protection layer. Figure 4 and Figure 5 As shown, the first angle is 45° and the second angle is 90°.

[0048] The thickness of the first prepreg is 0.5 mm to 2.5 mm, the first prepreg is a 2.5D woven fabric prepreg, the fiber of the first prepreg is a mixed fabric of quartz fiber and organic fiber, and the resin of the first prepreg is a phenolic resin. The organic fiber can be phenolic fiber, nylon fiber or aromatic sulfone fiber, and the type of quartz fiber can be B type, C type or D type.

[0049] S200, laying the inner prepreg blocks layer by layer on the load-bearing body in a warp-and-weft staggered manner, laying the outer prepreg blocks layer by layer on the inner prepreg blocks in a warp-and-weft staggered manner, to obtain a large-area heat-proof layer laying layer group.

[0050] Specifically, the inner layer prepreg blocks are laid first, and then the outer layer prepreg blocks are laid. The inner layer prepreg blocks are laid layer by layer in a warp and weft staggered manner, and the outer layer prepreg blocks are also laid layer by layer in a warp and weft staggered manner, that is, the inner layer prepreg blocks and the outer layer prepreg blocks are laid in sequence according to the laying angle sequence of 0°, 90°, 0°, 90°... to reduce the difference in various anisotropies.

[0051] It should be noted that the inner layer prepreg blocks and the outer layer prepreg blocks form a large-area heat protection layer by first laying and then curing. Therefore, when laying the inner layer prepreg blocks and the outer layer prepreg blocks, they are only laid in the area corresponding to the position of the large-area heat protection layer on the load-bearing body.

[0052] Considering that the special-shaped heat-proof layer is affected by high and low temperatures during the curing process, the load-bearing body will expand and shrink, and the deformation of each area of ​​the special-shaped surface is inconsistent. When laying the layers, it is not appropriate to use a whole prepreg cloth to lay the load-bearing body. Therefore, each layer of the large-area heat-proof layer laying layer group is formed by splicing 4 to 6 inner prepreg blocks, or by splicing 2 to 3 outer prepreg blocks. Specifically, each inner layer of the special-shaped heat-proof layer is formed by splicing 4 to 6 inner prepreg blocks, and each outer layer of the special-shaped heat-proof layer is formed by splicing 2 to 3 outer prepreg blocks, so as to improve the deformation capacity of the inner layer of the special-shaped heat-proof layer and improve the integrity of the outer layer of the special-shaped heat-proof layer. The splicing positions of two adjacent inner prepreg blocks in the same layer are connected by quartz stitching lines, and the splicing positions of two adjacent outer prepreg blocks in the same layer are also connected by quartz stitching lines to reduce the internal stress of the special-shaped heat-proof layer embryo during the curing process.

[0053] For ease of understanding, an example is given below: if the large-area heat-proof layer laying group has a total of six layers, from the inside to the outside the first, second and third layers are inner layers, and the fourth, fifth and sixth layers are outer layers, then the first, second and third layers are all formed by 4 to 6 inner layer prepreg blocks spliced ​​together by grouting, and the fourth, fifth and sixth layers are all formed by 2 to 3 outer layer prepreg blocks spliced ​​together by grouting.

[0054] S300, preparing the edge heat protection layer embryo.

[0055] The maximum thickness of the edge heat protection layer is 40mm to 60mm, and the minimum thickness is only 0.5mm. Its structure has the characteristics of small acute angles, R angles, bevels, etc. In order to ensure the appearance quality, the edge heat protection layer embryo is prepared by a molding process. During the molding process, the prepreg of the edge heat protection layer embryo includes mixed fibers, air fillers and resins. The mixed fibers include two or three of quartz fibers, carbon fibers or high silica fibers. The air fillers are one or two of hollow microspheres or boron carbide. The resin includes one or more of barium phenolic aldehyde, aminophenolic aldehyde or modified phenolic aldehyde.

[0056] Specifically, the prepreg of the edge heat protection layer embryo body is added into a mold with the same shape and size as the edge heat protection layer, and then the mold is closed for pre-pressing and demolding to obtain the edge heat protection layer embryo body.

[0057] S400, such as Figure 6 As shown, the thin wall area of ​​the marginal heat shield embryo was removed.

[0058] After the edge heat protection layer embryo is prepared by the molding process, the area with a thickness of less than 5mm is a thin-walled area. The rigidity of this area is weak and the deformation amount is large. If it is not cut off, it will affect the overall deformation amount of the special-shaped structure heat protection layer. Therefore, this step cuts off the thin-walled area with a thickness of less than 5mm on the edge heat protection layer embryo.

[0059] S500, such as Figure 6 As shown, the edge heat protection layer embryo body after the thin-wall area is cut off is placed on a molding tool, and a second prepreg is laid and pre-pressed in the area of ​​the molding tool corresponding to the cut-off part to obtain an edge heat protection layer composite embryo body.

[0060] In step S400, the thin-walled area of ​​the edge heat protection layer embryo body is cut off, and the purpose of step S500 is to form the cut-off thin-walled area by laying the second prepreg and pre-pressing, so the second prepreg is laid and pre-pressed in the area of ​​the molding tool corresponding to the cut-off part. It should be noted that at least part of the second prepreg is laid on the edge heat protection layer embryo body after the thin-walled area is cut off, so that the thin-walled area formed by the second prepreg after pre-pressing is fixedly connected to the edge heat protection layer embryo body after the thin-walled area is cut off.

[0061] The thickness of the second prepreg is 0.5mm to 1mm, the second prepreg is a 2.5D woven fabric prepreg, the fiber of the second prepreg is a mixed fabric of quartz fiber and organic fiber, and the resin of the second prepreg is phenolic resin. The organic fiber can be phenolic fiber, nylon fiber or aromatic sulfone nylon fiber, and the type of quartz fiber can be type B, type C or type D. Through the three-dimensional model, the cross-sections of several thin-walled areas can be cut, and the thickness and number of layers of the second prepreg can be designed according to the cross-sections, and then laid layer by layer to be consistent with the shape of the thin-walled area of ​​the edge heat protection layer, and then pre-pressed by mold closing to ensure that the shape is formed to near net size.

[0062] S600, embedding the composite embryo of the edge heat protection layer into the prepreg laying layer group to obtain the embryo of the heat protection layer.

[0063] The edge of the edge heat protection layer composite embryo is placed between two adjacent prepreg laying layers, so that after curing, the edge heat protection layer composite embryo is fixedly connected to the large-area heat protection layer laying layer group.

[0064] S700, curing the heat protection layer embryo to obtain a heat protection layer with a special structure.

[0065] After curing, the special-shaped heat-proof layer is fixed on the load-bearing body. The curing is carried out through step temperature. When the curing temperature is 80℃~100℃, the heat preservation is 6h~8h, and when the curing temperature is 110℃~130℃, the heat preservation is 3h~4h.

[0066] In some embodiments, when curing is performed by step temperature, the temperature of the secondary pre-compacted heat-resistant layer embryo assembly is gradually increased from room temperature to 80°C to 100°C, and after increasing to 80°C to 100°C, it is kept warm for 6h to 8h; after keeping warm for 6h to 8h, the temperature is gradually increased to 110°C to 130°C, and then increased to 110°C to 130°C and kept warm for 3h to 4h; after keeping warm for 3h to 4h, the temperature is increased to the set maximum curing temperature, and when the temperature reaches the maximum curing temperature, the temperature is lowered so that the secondary pre-compacted heat-resistant layer embryo assembly is gradually cooled to room temperature. In some embodiments, the maximum curing temperature is 180°C.

[0067] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0068] In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0069] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A method for forming a special-shaped heat-proof layer, characterized in that: include: Preparing a first prepreg and cutting the first prepreg at a first angle to obtain an inner prepreg block, and cutting the first prepreg at a second angle to obtain an outer prepreg block; The inner layer prepreg blocks are laid layer by layer on the load-bearing body in a warp and weft staggered manner, and the outer layer prepreg blocks are laid layer by layer on the inner layer prepreg blocks in a warp and weft staggered manner to obtain a large-area heat-proof layer laying layer group; Prepare the edge heat protection layer embryo; Cutting off the thin wall area on the edge heat protection layer embryo; Placing the edge heat protection layer embryo body after cutting off the thin-walled area on a molding tool, and laying a second prepreg in the area of ​​the molding tool corresponding to the cut-off part and pre-pressing it to obtain an edge heat protection layer composite embryo body; The composite embryo of the edge heat protection layer is embedded in the prepreg laying layer group to obtain a special-shaped structure heat protection layer embryo; The embryo of the special-shaped heat-proof layer is cured to obtain the special-shaped heat-proof layer.

2. The method for forming a special-shaped structure heat protection layer according to claim 1, characterized in that: The curing treatment is carried out by step temperature. When the curing temperature is 80° C. to 100° C., the temperature is kept for 6 h to 8 h. When the curing temperature is 110° C. to 130° C., the temperature is kept for 3 h to 4 h.

3. The method for forming a special-shaped structure heat protection layer according to claim 1, characterized in that: The thickness of the first prepreg is 0.5 mm to 2.5 mm. The first prepreg is a 2.5D woven fabric prepreg. The fibers of the first prepreg are a mixed fabric of quartz fibers and organic fibers. The resin of the first prepreg is a phenolic resin.

4. The method for forming a special-shaped heat-proof layer according to claim 1, characterized in that: The thickness of the second prepreg is 0.5 mm to 1 mm, the second prepreg is a 2.5D woven fabric prepreg, the fibers of the second prepreg are a mixed braid of quartz fibers and organic fibers, and the resin of the second prepreg is phenolic resin.

5. The method for forming a special-shaped structure heat protection layer according to claim 1, characterized in that: The edge heat protection layer embryo is prepared by a molding process.

6. The method for forming a special-shaped structure heat protection layer according to claim 5, characterized in that: The prepreg material of the edge heat protection layer embryo body includes mixed fibers, air-energy fillers and resins, wherein the mixed fibers include two or three of quartz fibers, carbon fibers or high-silica fibers, the air-energy fillers are one or two of hollow microbeads or boron carbides, and the resin includes one or more of barium phenolic formaldehyde, aminophenolic formaldehyde or modified phenolic formaldehyde.

7. The method for forming a special-shaped structure heat protection layer according to any one of claims 1 to 6, characterized in that: The first angle is 45°, and the second angle is 90°.

8. The method for forming a special-shaped heat-proof layer according to any one of claims 1 to 6, characterized in that: Each layer of the large-area heat-proof layer laying layer group is formed by splicing 4 to 6 inner layer prepreg blocks, or is formed by splicing 2 to 3 outer layer prepreg blocks.

9. The method for forming a special-shaped structure heat protection layer according to claim 8, characterized in that: The splicing positions of two adjacent inner prepreg blocks in the same layer are connected by quartz stitching lines, and the splicing positions of two adjacent outer prepreg blocks in the same layer are also connected by quartz stitching lines.

10. The method for forming a special-shaped heat-proof layer according to any one of claims 1 to 6, characterized in that: The thin-walled area is an area with a thickness less than 5 mm.

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