A method for forming a heat shield layer with a special-shaped structure

Abstract

The application discloses a special-shaped structure heat-proof layer forming method and belongs to the technical field of composite material forming. The special-shaped structure heat-proof layer forming method comprises the following steps: preparing an edge heat-proof layer embryo; preparing prepreg and laying the prepreg on a stitching tool layer by layer; penetrating and stitching several layers of the prepreg close to an outer shape surface and pointing the prepreg, the pointing being along the hole position of the penetrating and stitching, so as to obtain a large-area heat-proof layer laying layer group; embedding the edge heat-proof layer embryo in the large-area heat-proof layer laying layer group, so as to obtain a heat-proof layer embryo; and pre-pressing and curing the heat-proof layer embryo, so as to obtain the special-shaped structure heat-proof layer.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of composite material forming, and particularly relates to a forming method for a heat-proof layer of a special-shaped structure. BACKGROUND

[0002] Most traditional aircrafts are regular cylindrical or conical structures. In order to meet aerodynamic requirements, the outer shape of a high-speed aircraft is designed as a special-shaped structure to maintain a high lift-drag ratio. Since the flight environment of the aircraft needs to go through a rarefied gas layer and a dense atmosphere layer, aerodynamic load and aerodynamic heating are extremely severe. In a long-time hovering environment, high-temperature scouring causes internal resin ablation and carbonization of the heat-proof layer, and under the condition of temperature difference between the inside and outside, internal stress changes caused by the linear expansion difference between the load-bearing body and the heat-proof layer greatly test the interlayer strength of the heat-proof layer. In order to better adapt to the severe flight environment, the thermal protection structure is required to have the characteristics of high-temperature resistance, ablation resistance and high interlayer bonding strength.

[0003] In the related art, the heat-proof layer of a special-shaped structure aircraft may be delaminated and fail under the action of heat in a severe thermal environment. SUMMARY

[0004] The application aims to at least solve the technical problem of delamination and failure of the heat-proof layer in the related art. To this end, the application provides a forming method for a heat-proof layer of a special-shaped structure.

[0005] The application provides a forming method for a heat-proof layer of a special-shaped structure, which comprises the following steps:

[0006] A rib heat-proof layer blank is prepared;

[0007] A prepreg is prepared and laid layer by layer on a stitching tool;

[0008] Several layers of the prepreg close to the outer shape are through-stitched and pointed, the pointing is along the hole position of the through-stitching, and a large-area heat-proof layer laying layer group is obtained;

[0009] The rib heat-proof layer blank is embedded in the large-area heat-proof layer laying layer group, and a heat-proof layer blank is obtained;

[0010] The heat-proof layer blank is pre-pressed and cured to obtain the heat-proof layer of the special-shaped structure.

[0011] In some embodiments, the pre-pressing and curing of the heat-proof layer blank to obtain the heat-proof layer of the special-shaped structure comprises:

[0012] The heat-proof layer blank is pre-pressed for the first time to obtain a pre-compacted heat-proof layer blank;

[0013] The pre-compacted heat-proof layer blank is transferred to a curing tool;

[0014] laying a process skin on the outer surface of the pre-compacted thermal protection layer blank and stitching the process skin and the pre-compacted thermal protection layer blank together to obtain the pre-compacted thermal protection layer blank assembly;

[0015] performing a second pre-pressing process on the pre-compacted thermal protection layer blank assembly to obtain a second pre-compacted thermal protection layer blank assembly;

[0016] performing a curing process on the second pre-compacted thermal protection layer blank assembly and cleaning the process skin to obtain a thermal protection layer with a special-shaped structure.

[0017] In some embodiments, the transferring of the pre-compacted thermal protection layer blank to the curing tool includes:

[0018] sleeving the transfer tool to the pre-compacted thermal protection layer blank;

[0019] fixedly connecting the transfer tool and the stitching tool;

[0020] stitching the pre-compacted thermal protection layer blank on the transfer tool through the stitching tool;

[0021] transferring the stitching tool to a dismounting platform and dismounting the stitching tool;

[0022] transferring the transfer tool so that the pre-compacted thermal protection layer blank is sleeved to the curing tool;

[0023] dismounting the transfer tool.

[0024] In some embodiments, the process skin includes a plurality of first process skins and a plurality of second process skins.

[0025] The laying of the process skin on the outer surface of the pre-compacted thermal protection layer blank includes laying the first process skins and leaving a gap of 30mm to 40mm between two adjacent first process skins, and laying the second process skins in the gap.

[0026] In some embodiments, the thickness of the first process skin is 1mm to 3mm, the number of the first process skins is 8 to 10, the thickness of the second process skin is 0.2mm to 0.6mm, and the width of the second process skin is 50mm to 60mm.

[0027] In some embodiments, the secondary pre-compacted thermal protection layer blank assembly comprises the process skin and a secondary pre-compacted thermal protection layer blank, and the forming method further comprises: after the second pre-compaction treatment, removing the process skin on the secondary pre-compacted thermal protection layer blank assembly, trimming the secondary pre-compacted thermal protection layer blank, and then laying the process skin on the outer shape surface of the secondary pre-compacted thermal protection layer blank and sewing the process skin and the secondary pre-compacted thermal protection layer blank together to form the secondary pre-compacted thermal protection layer blank assembly.

[0028] In some embodiments, the pre-compaction temperature of the first pre-compaction treatment is 30-80 DEG C, and the pre-compacted thermal protection layer blank is further subjected to a trimming treatment after the first pre-compaction treatment.

[0029] In some embodiments, the pre-compaction temperature of the second pre-compaction treatment is 50-80 DEG C, and the pressure of the second pre-compaction treatment comprises a vacuum pressure and an external pressure of 0.1-0.5 MPa.

[0030] In some embodiments, the row span of the needle distance of the through sewing is 10-50 mm, and the column span is also 10-50 mm.

[0031] In some embodiments, the curing treatment is performed by a step temperature, and the holding time is 6-8 h at a curing temperature of 80-100 DEG C and 3-4 h at a curing temperature of 110-130 DEG C.

[0032] The present application has at least the following beneficial effects:

[0033] The special-shaped structure thermal protection layer forming method of the present application performs through sewing and pointing on several layers of pre-impregnated material close to the outer shape surface, and the pointing uses the hole positions of the through sewing, thereby improving the interlayer connection effect of the thermal protection layer, and the pointing uses the hole positions of the through sewing without adding new hole positions, thereby reducing the damage to the fibers during the sewing process.

[0034] The special-shaped structure heat-proof layer includes two parts of a large-area heat-proof layer and a ridge heat-proof layer. The thickness of each part of the large-area heat-proof layer is uniform, and the thickness of the ridge heat-proof layer is non-uniform, in the form of thick at one end and thin at the other end. The special-shaped structure heat-proof layer forming method of the present application clearly defines the processing sequence of the special-shaped structure heat-proof layer, processes the ridge heat-proof layer embryo first, then forms a large-area heat-proof layer laying layer group by laying the prepreg, and embeds the ridge heat-proof layer embryo in the large-area heat-proof layer laying layer group, so that the large-area heat-proof layer laying layer group and the ridge heat-proof layer embryo are cured synchronously to form a whole, and then the special-shaped structure heat-proof layer is obtained. According to the special-shaped structure heat-proof layer forming method provided by the present application, the processing difficulty of the heat-proof layer can be simplified, and the structural strength of the heat-proof layer can be ensured. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0036] Figure 1 The cross-sectional schematic diagram of the first end and the second end of the special-shaped structure heat-proof layer in one or more embodiments of the present application is shown.

[0037] Figure 2 The structural schematic diagram of the special-shaped structure heat-proof layer in one or more embodiments of the present application is shown.

[0038] Figure 3 The flowchart of the special-shaped structure heat-proof layer forming method in one or more embodiments of the present application is shown.

[0039] Reference signs: 1-first end, 2-second end, 1.1-upper part, 1.2-lower part, 1.21-first straight edge, 1.22-second straight edge, 1.23-curved edge. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0041] It should be noted that all directional indications in the embodiments of the present application are only used to explain the relative position relationship, movement condition, etc. between the components in a certain posture, and if the certain posture changes, the directional indications also change accordingly.

[0042] In the present application, unless otherwise explicitly specified and limited, the terms "connection", "fixation" and the like should be understood in a broad sense, for example, "fixation" can be fixed connection, or detachable connection, or integral; can be mechanical connection, or electrical connection; can be directly connected, or indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship of two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0043] In addition, in the present application, the description such as "first", "second" and the like is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can be explicitly or implicitly included at least one of the features. In addition, the technical solutions of various embodiments can be combined with each other, but it must be based on the fact that a person skilled in the art can realize it, when the combination of technical solutions contradicts each other or cannot be realized, it should be considered that the combination of technical solutions does not exist, nor within the protection scope required by the present application.

[0044] Most of the traditional aircrafts are regular shapes such as cylindrical or conical structures. In order to meet the aerodynamic requirements, the high-speed aircrafts are designed as special-shaped structures to maintain a high lift-drag ratio. Due to the need to pass through the rarefied gas layer and the dense atmosphere layer, the aerodynamic load and aerodynamic heating are extremely severe. In the long-time air environment, the high-temperature scouring causes the resin ablation and carbonization inside the thermal protection layer, and under the condition of temperature difference between the inside and outside, the internal stress change caused by the linear expansion difference between the load-bearing body and the thermal protection layer tests the interlayer strength of the thermal protection layer. In order to better adapt to the severe flight environment, the thermal protection structure is required to have the characteristics of high temperature resistance, ablation resistance and high interlayer bonding strength.

[0045] The inventors have found that in the related art, the aircraft with special-shaped structure has the problem of delamination failure of the thermal protection layer under the action of heat in the severe thermal environment due to poor interlayer connection of the thermal protection layer itself.

[0046] In the related art, the aircraft with special-shaped structure has the technical problem of delamination failure of the thermal protection layer under the action of heat in the severe thermal environment. The special-shaped structure thermal protection layer forming method provided in the embodiments of the present application can at least solve the technical problem of delamination failure of the thermal protection layer to a certain extent.

[0047] In some embodiments of the present application, the following special-shaped structure thermal protection layer is formed by the special-shaped structure thermal protection layer forming method:

[0048] For example, Figure 1 and Figure 2As shown, the irregularly shaped heat-insulating layer includes a first end 1 and a second end 2, which are connected by a tapered surface. The second end 2 of the irregularly shaped heat-insulating layer has a circular cross-section. The upper part 1.1 of the first end 1 has a U-shaped cross-section, and the lower part 1.2 of the first end 1 has a cross-section including a first straight side 1.21, a second straight side 1.22, and a curved side 1.23. One end of the first straight side 1.21 and one end of the second straight side 1.22 are respectively connected to the two ends of the U-shape, and both the first straight side 1.21 and the second straight side 1.22 are parallel to the center line of the U-shape. The other end of the first straight side 1.21 and the other end of the second straight side 1.22 are connected by the curved side 1.23, which is arc-shaped and located away from the center of the U-shape.

[0049] like Figure 2 As shown, this irregularly shaped heat-insulating layer consists of two edge heat-insulating layers ( Figure 2 The structure consists of a central dashed area and a large-area heat-insulating layer (except for the edge heat-insulating layer, all other areas are large-area heat-insulating layers). The thickness of the large-area heat-insulating layer is relatively uniform. The edge heat-insulating layer is located near the first end and has an uneven thickness, being thicker at one end and thinner at the other. The maximum thickness of the edge heat-insulating layer is 40mm to 60mm, and the minimum thickness is only 0.5mm. This irregularly shaped heat-insulating layer features small acute angles, rounded angles, and bevels. This irregularly shaped heat-insulating layer is a thin-walled irregular structure with poor rigidity. Furthermore, the thickness of this irregularly shaped heat-insulating layer varies throughout, resulting in inconsistent rigidity in different parts within the multi-interface structure.

[0050] It should be noted that the irregular structure heat-resistant layer molding method provided by this invention can be used to mold the aforementioned irregular structure heat-resistant layer, and of course, it can also be used to mold other irregular structure heat-resistant layers, such as those described in patent publication number CN116372506A. Figure 1 The disclosed irregular structure can also be found in patent publication number CN111196048B. Figure 2 The disclosed irregular structures are not limited in this application.

[0051] The following describes the molding method for irregularly shaped heat-resistant layers, such as... Figure 3 As shown, the method for forming an irregularly shaped heat-resistant layer includes steps S100, S200, S300, S400 and S500.

[0052] S100 was used to prepare the edge heat-insulating layer preform.

[0053] The maximum thickness of the edge heat protection layer is 40mm-60mm, and the minimum thickness is only 0.5mm. The structure has the characteristics of small acute angle, R angle, slope, etc. In order to ensure the appearance quality, the edge heat protection layer blank can be prepared by a molding process. The prepreg of the edge heat protection layer blank includes hybrid fibers, empty energy fillers and resin. The hybrid fibers include two or three of quartz fiber, carbon fiber or high-silica fiber, the empty energy filler is one or both of hollow microbeads or boron carbide, and the resin includes one or more of barium phenolic, ammonia phenolic or modified phenolic. Specifically, the prepreg of the edge heat protection layer blank is added to a mold with the same shape and size as the edge heat protection layer, and then the mold is pre-pressed and demolded to obtain the edge heat protection layer blank.

[0054] S200, the prepreg is prepared and the prepreg is laid layer by layer on the stitching tool.

[0055] The prepreg is used for forming a large-area heat protection layer, the thickness of the prepreg is 0.5mm-2.5mm, the prepreg is a 2.5D woven fabric prepreg, the fibers of the prepreg use quartz fibers, the type of the quartz fibers can be selected from B type, C type or D type, and the resin of the prepreg uses barium phenolic or boron phenolic resin.

[0056] The outer shape of the stitching tool is the same as the inner shape of the heat protection layer, the stitching tool can automatically stitch the prepreg, the shape of the stitching tool is related to the shape of the heat protection layer, and the structure of the stitching tool is various, which is not limited in the present application. Before using the stitching tool, alcohol or acetone can be used to clean the stitching tool, and the surface of the stitching tool can be protected by pasting adhesive cloth to prevent the prepreg from adhering to the surface of the stitching tool.

[0057] S300, several layers of prepreg close to the outer shape are penetrated and stitched, and the jointing is along the hole position of the penetration stitching, and a large-area heat protection layer laying layer group is obtained.

[0058] It should be noted that the large-area heat protection layer laying layer group includes a plurality of prepreg laying layers, and each layer of the large-area heat protection layer laying layer group is formed by splicing a plurality of prepregs. The penetration stitching is to stitch several layers of prepreg laying layers close to the outer shape together, so that the connection of the several layers of prepreg laying layers close to the outer shape is enhanced. The jointing is to stitch the adjacent two prepregs in the same prepreg laying layer together, so that the plurality of prepregs in the same prepreg laying layer form a whole through jointing, and the connection of the plurality of prepregs in the same prepreg laying layer is enhanced. The penetration stitching and the jointing can be realized by the stitching tool.

[0059] The layers closest to the outer surface can be the first and second layers from the outside in, or the first, second, and third layers from the outside in, or the first, second, third, and fourth layers from the outside in. The specific number of layers is related to the total number of layers in the large-area heat insulation layer assembly, and can be designed to suit the user's needs. In some embodiments, the first and second layers from the outside in are stitched together, and both the first and second layers are grouted.

[0060] Experiments have shown that the optimal stitch spacing for through-the-hole sutures is 10mm to 50mm for both row and column spacing.

[0061] In harsh thermal environments, the resin undergoes high-temperature carbonization and decomposition, weakening the interlayer adhesion of the heat-resistant layer and posing a risk of delamination. The present invention's irregular-structure heat-resistant layer molding method involves through-stitching and grouting several layers of prepreg close to the outer surface. The grouting utilizes the holes from the through-stitching, improving the interlayer bonding effect of the heat-resistant layer. The grouting also avoids adding new holes, reducing fiber damage during the stitching process. Experimental verification shows that after adding through-stitching and grouting, the interlayer shear strength of the heat-resistant layer at 300°C is increased by approximately 60% compared to the unstitched layer.

[0062] S400, embedding the edge heat-insulating layer preform into the large-area heat-insulating layer assembly to obtain the heat-insulating layer preform.

[0063] At least the edge portion of the edge heat-insulating layer preform is embedded between two adjacent prepreg layers to obtain the heat-insulating layer preform. It should be noted that the edge heat-insulating layer preform can be embedded in the large-area heat-insulating layer assembly during the fabrication process, or it can be embedded in the large-area heat-insulating layer assembly after its fabrication is completed.

[0064] like Figure 1 and Figure 2 The first end 1 of the irregularly shaped heat-insulating layer shown is the small end, and the second end 2 is the large end. If, in steps S300 and S400, the first end 1 is on top and the second end 2 is on the bottom, that is, the edge heat-insulating layer preform is located at the upper end of the sewing fixture, the edge heat-insulating layer preform will lack support after being buried in the large-area heat-insulating layer layer assembly, and the edge heat-insulating layer preform is prone to sliding and misaligning downwards. The outer shape of the sewing fixture and the inner shape of the irregularly shaped heat-insulating layer are the same. Therefore, if the heat-insulating layer prepared according to this application is used... Figure 1 and Figure 2 In the case of the irregular structure shown, in steps S300 and S400, the small end of the sewing fixture is at the bottom and the large end is at the top, so that the edge heat-insulating layer preform is located at the lower end of the sewing fixture. The lower end of the sewing fixture can support the edge heat-insulating layer preform, so as to avoid misalignment of the edge heat-insulating layer preform to a certain extent.

[0065] S500, pre-pressing and curing the heat protection layer blank to obtain a heat protection layer with a special shape.

[0066] The heat protection layer blank is first pre-pressed, and then cured. The pre-pressing process helps to preliminarily compact the prepreg in the mold, so that the resin can be more uniformly distributed between the fibers, improving the impregnation effect. In this way, the resin can more fully infiltrate the fibers during the subsequent curing process, forming a stronger interfacial bonding force.

[0067] Step S500 can include steps S510, S520, S530, S540, S550, and S560.

[0068] S510, first pre-pressing the heat protection layer blank to obtain a pre- compacted heat protection layer blank.

[0069] The heat protection layer blank is first pre-pressed. Specifically, the heat protection layer blank can be sealed by a vacuum bag, and pre-pressed by vacuum pressure. The pre-pressing temperature of the first pre-pressing is 30-80°C. After completing the pre-pressing, the vacuum bag is opened, and the wrinkles and depressions on the surface of the pre- compacted heat protection layer blank are trimmed.

[0070] S520, transferring the pre- compacted heat protection layer blank to a curing tool.

[0071] The pre- compacted heat protection layer blank is transferred to the curing tool to facilitate subsequent curing treatment by the curing tool.

[0072] Step S520 can include steps S521, S522, S523, S524, S525, and S526.

[0073] S521, sleeving a transfer tool outside the pre- compacted heat protection layer blank.

[0074] The inner surface of the transfer tool is the same as the outer shape of the heat protection layer. The shape of the transfer tool is related to the shape of the heat protection layer, and the structure of the transfer tool is various, which is not limited in the present application. Before using the transfer tool, alcohol or acetone can be used to clean the transfer tool. Adhesive cloth can be laid on the inner surface of the transfer tool for protection to prevent the prepreg from adhering to the inner surface of the transfer tool.

[0075] S522, fixedly connecting the transfer tool and the stitching tool.

[0076] After the transfer tool is sleeved outside the pre- compacted heat protection layer blank, the transfer tool and the stitching tool are fixed to facilitate step S523. The fixing can be achieved by bolt connection or clamping.

[0077] S523, stitching the pre- compacted heat protection layer blank on the transfer tool by the stitching tool.

[0078] The pre-compacted heat protection layer blank is fixed on the transfer tool by stitching, so that the pre-compacted heat protection layer blank is fixed on the transfer tool by stitching, and the stitching between the pre-compacted heat protection layer blank and the transfer tool is realized by the stitching tool. Here, the stitching can adopt a through-stitching mode, and the stitching density is 20% to 40% of the through-stitching density in the step S300, so as to reduce the damage of the over-dense stitching to the strength of the heat protection layer and to meet the fixed connection function.

[0079] S524, the stitching tool is transferred to the disassembly platform, and the stitching tool is disassembled.

[0080] After the stitching is completed, the whole formed by the stitching tool, the transfer tool and the pre-compacted heat protection layer blank on the transfer tool can be transferred to the disassembly platform, and then the stitching tool is disassembled, so that the stitching tool is separated from the transfer tool.

[0081] S525, the transfer tool is transferred, so that the pre-compacted heat protection layer blank is sleeved on the curing tool.

[0082] The transfer tool is transferred to sleeve the pre-compacted heat protection layer blank fixed on the transfer tool on the curing tool. Specifically, after the pre-compacted heat protection layer blank is sleeved on the curing tool, the transfer tool can be fixed and connected with the curing tool by bolt connection, and the downward pressure formed by the bolt tightening process applies a certain pressure to the pre-compacted heat protection layer blank, so that the pre-compacted heat protection layer blank is sleeved in place downward.

[0083] The outer surface of the curing tool is the same as the inner profile surface of the heat protection layer, the shape of the curing tool is related to the shape of the heat protection layer, and the structure of the curing tool is various, which is not limited in the present application.

[0084] As shown in the special-shaped structure heat protection layer shown in Figure 1 and Figure 2 , the first end 1 is a small end, and the second end 2 is a large end. If the special-shaped structure shown in Figure 1 and Figure 2 is adopted, the small end of the curing tool and the transfer tool is on the top and the large end is on the bottom when the step S525 is performed, so as to ensure that the pre-compacted heat protection layer blank can be smoothly sleeved on the curing tool. Specifically, the transfer tool can be transferred by a lifting appliance, and when the transfer tool is transferred, i.e. when the step S525 is performed, the lifting hook of the lifting appliance lifts the small end of the transfer tool, so that the large end of the pre-compacted heat protection layer blank is on the bottom and the small end is on the top, so that the pre-compacted heat protection layer blank can be smoothly sleeved on the curing tool.

[0085] S526, the transfer tool is disassembled.

[0086] After the pre-compacted thermal protection layer embryo is assembled in place, the transfer tooling can be disassembled and removed. Specifically, the stitching line between the transfer tooling and the pre-compacted thermal protection layer embryo is cut off, so that the transfer tooling is separated from the pre-compacted thermal protection layer embryo.

[0087] S530, lay the process skin on the outer shape surface of the pre-compacted thermal protection layer and stitch the process skin and the pre-compacted thermal protection layer embryo together to obtain a pre-compacted thermal protection layer embryo assembly.

[0088] The process skin needs to be prepared in advance. The process skin can be formed by using a pre-impregnated material with a thickness of 0.2mm-0.4mm in a rigid mold with the same shape as the outer shape surface of the special-shaped structure thermal protection layer. Considering that the skin still needs a certain rigidity during the pressing process of the thermal protection layer to ensure the overall appearance of the thermal protection layer, poor rigidity can cause local arching, skin cracking and other problems, and the thickness of the skin is preferably 1mm-3mm. The pre-compacted thermal protection layer embryo assembly includes a pre-compacted thermal protection layer embryo and a process skin stitched on the pre-compacted thermal protection layer embryo.

[0089] To ensure that the skin is more closely attached to the pre-compacted thermal protection layer embryo, the process skin includes multiple first process skins and second process skins. When laying the process skin, first process skins are laid first, and a gap of 30mm-40mm is reserved between adjacent two first process skins, and then second process skins are laid in the gap. The thickness of the first process skin is 1mm-3mm, the number of the first process skin is 8-10, the thickness of the second process skin is 0.2mm-0.6mm, and the width of the second process skin is 50mm-60mm. When splicing, considering the difference in linear expansion coefficient of the metal mold during high temperature process, the skin at the splicing position will be misaligned and extruded, resulting in wrinkles and depressions on the surface of the special-shaped structure thermal protection layer. According to the calculation of the solidification temperature difference and the thermal expansion coefficient of the product, it is best to reserve a gap of 30mm-40mm at the splicing position, but the edge of the first process skin with a larger thickness will still cause the surface of the thermal protection layer to appear depressed when it contacts the special-shaped structure thermal protection layer. Therefore, by preparing a second process skin with a thickness of 0.2mm-0.6mm, cutting it into a rectangular strip with a width of 50mm-60mm, and placing the second process skin in the splicing gap, the surface quality of the special-shaped structure thermal protection layer is ensured. After this design, the maximum protrusion or depression of the special-shaped structure thermal protection layer is ≤0.6mm, and the outer shape surface quality is good.

[0090] In steps S540 and S550 below, the process skin is subjected to vacuum pressure and external pressure, and the skin is at risk of shifting and moving, which may cause large extrusion wrinkles or indentations on the surface of the special-shaped structure heat protection layer. Through research, it is found that by punching holes (hole diameter Φ ≤ 2 mm) on the upper and lower ends of the skin, and then using a suture line (which can be an organic fiber suture line), the skin is locally sutured and connected to the pre-compacted heat protection layer embryo by caulking, which can ensure the stability of the subsequent skin position and the quality of the outer shape of the special-shaped structure heat protection layer.

[0091] S540, the pre-compacted heat protection layer embryo assembly is subjected to second pre-pressing treatment to obtain a second pre-compacted heat protection layer embryo assembly.

[0092] The pre-compacted heat protection layer embryo and the process skin thereon are subjected to second pre-pressing treatment together, and the skin can maintain the shape of the pre-compacted heat protection layer embryo as a whole during the second pre-pressing treatment.

[0093] The pre-pressing temperature of the second pre-pressing is 50-80°C, and the pressure of the second pre-pressing treatment includes vacuum pressure and 0.1-0.5 MPa external pressure. That is, in addition to vacuum pressure, 0.1-0.5 MPa external pressure is also used for pre-pressing during the second pre-pressing.

[0094] The second pre-compacted heat protection layer embryo assembly includes a second pre-compacted heat protection layer embryo and a process skin sutured thereon. In some embodiments, step S550 is further included, after the second pre-pressing treatment (i.e., after step S540), the process skin on the second pre-compacted heat protection layer embryo assembly is removed, the second pre-compacted heat protection layer embryo is trimmed, and then the process skin is laid on the outer shape of the second pre-compacted heat protection layer embryo and sutured together with the second pre-compacted heat protection layer embryo to form a second pre-compacted heat protection layer embryo assembly.

[0095] That is, after step S540, the process skin is removed from the second pre-compacted heat protection layer embryo assembly, so that the operator can clean the second pre-compacted heat protection layer embryo of the second pre-compacted heat protection layer embryo assembly separately to ensure the dimensional accuracy of the special-shaped structure heat protection layer after curing.

[0096] S560, the second pre-compacted heat protection layer embryo assembly is subjected to curing treatment and the process skin is cleaned to obtain a special-shaped structure heat protection layer.

[0097] Specifically, the curing treatment is performed first, and after the curing treatment is completed, the process skin is cleaned.

[0098] The curing treatment is performed by step temperature, and when the curing temperature is 80-100°C, the temperature is kept for 6-8h, and when the curing temperature is 110-130°C, the temperature is kept for 3-4h.

[0099] In some embodiments, when the curing process is performed by step temperature, the temperature of the secondary pre-compacted thermal protection layer blank assembly is gradually increased from room temperature to 80-100℃, and after the temperature is increased to 80-100℃, the temperature is kept for 6-8 hours; after the temperature is kept for 6-8 hours, the temperature is gradually increased to 110-130℃, and after the temperature is increased to 110-130℃, the temperature is kept for 3-4 hours; after the temperature is kept for 3-4 hours, the temperature is increased to the highest curing temperature, and after the temperature reaches the highest curing temperature, the temperature is decreased so that the secondary pre-compacted thermal protection layer blank assembly is gradually cooled to room temperature.

[0100] In some embodiments, the highest curing temperature is 180℃.

[0101] During the curing process, the secondary pre-compacted thermal protection layer blank assembly is also subjected to vacuumizing treatment, and the secondary pre-compacted thermal protection layer blank assembly is subjected to external pressure with a pressure of 0.1-0.5Mpa. After the curing process, the process skin, vacuum bag and the like on the surface are removed, and the irregularly shaped thermal protection layer is obtained.

[0102] After the irregularly shaped thermal protection layer is obtained, the irregularly shaped thermal protection layer can be subjected to polishing and the like to adjust the dimensional accuracy of the irregularly shaped thermal protection layer.

[0103] After the irregularly shaped thermal protection layer is obtained, the irregularly shaped thermal protection layer can be installed on the load-bearing body according to the following steps:

[0104] S1000, a bonding agent is coated on the inner profile surface of the irregularly shaped thermal protection layer and the outer profile surface of the load-bearing body;

[0105] S2000, the irregularly shaped thermal protection layer is sleeved on the load-bearing body so that the irregularly shaped thermal protection layer is bonded to the load-bearing body.

[0106] After the irregularly shaped thermal protection layer is sleeved on the load-bearing body, the irregularly shaped thermal protection layer is kept for 72-96 hours, the time used in the sleeving process is not more than 30 minutes, and the ambient temperature in the sleeving process is 20-30℃, and the humidity is 45-75%RH.

[0107] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in the present specification.

[0108] In addition, the technical solutions among various embodiments can be combined with each other, but it must be based on that a person skilled in the art can realize, when the combination of technical solutions appears contradictory or cannot be realized, it should be considered that the combination of technical solutions does not exist, and is not within the protection scope required by the present application.

[0109] Although the embodiments of the present application have been shown and described, those skilled in the art can understand that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and purposes of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. A method for forming an irregularly shaped heat-resistant layer, characterized in that, include: A preform for the edge heat-insulating layer was prepared; Prepare the prepreg and lay the prepreg layer by layer on the sewing fixture; Several layers of the prepreg close to the outer surface are stitched and grouted together, with the grooving following the holes of the through stitches, to obtain a large-area heat-insulating layer assembly. The edge heat-insulating layer preform is embedded in the large-area heat-insulating layer assembly to obtain the heat-insulating layer preform; The heat-insulating layer preform is pre-pressed and cured to obtain the irregularly shaped heat-insulating layer; The process of pre-pressing and curing the heat-insulating layer preform to obtain the irregularly shaped heat-insulating layer includes: The heat-insulating layer preform is subjected to a first pre-compression treatment to obtain a pre-compressed heat-insulating layer preform; Transfer the pre-compacted heat-insulating layer preform to the curing fixture; The process skin is laid on the outer surface of the precompacted heat-insulating layer preform and the process skin is sewn together with the precompacted heat-insulating layer preform to obtain the precompacted heat-insulating layer preform assembly. A second pre-compression treatment is performed on the pre-compacted heat-insulating layer preform assembly to obtain a secondary pre-compacted heat-insulating layer preform assembly. The preform of the secondary pre-compacted heat-insulating layer is cured and the process skin is cleaned to obtain the irregular structure heat-insulating layer. The step of transferring the pre-compacted heat-resistant layer preform onto the curing fixture includes: The transfer tooling is fitted onto the pre-compacted heat-insulating layer embryo; The transfer fixture is fixedly connected to the sewing fixture; The pre-compacted heat-insulating layer preform is sewn onto the transfer fixture using the sewing fixture; The sewing fixture is transferred to the disassembly platform and then disassembled. Transfer the transfer fixture so that the pre-compacted heat-insulating layer preform is fitted onto the curing fixture; Disassemble the transfer fixture.

2. The method for forming an irregularly shaped heat-resistant layer according to claim 1, characterized in that, The process skin includes multiple first process skins and multiple second process skins; The step of laying the process skin on the outer surface of the pre-compacted heat-insulating layer blank includes: laying the first process skin and leaving a gap of 30mm to 40mm between two adjacent pieces of the first process skin; The second process skin is laid in the gap.

3. The method for forming an irregularly shaped heat-resistant layer according to claim 2, characterized in that, The thickness of the first process skin is 1mm to 3mm, the number of the first process skins is 8 to 10, the thickness of the second process skin is 0.2mm to 0.6mm, and the width of the second process skin is 50mm to 60mm.

4. The method for forming an irregularly shaped heat-resistant layer according to claim 1, characterized in that, The secondary precompacted heat-resistant layer preform assembly includes the process skin and the secondary precompacted heat-resistant layer preform. The forming method further includes: after the second precompacting process, removing the process skin from the secondary precompacted heat-resistant layer preform assembly, trimming the secondary precompacted heat-resistant layer preform, laying the process skin on the outer surface of the secondary precompacted heat-resistant layer preform after trimming, and sewing the process skin to the secondary precompacted heat-resistant layer preform together to form the secondary precompacted heat-resistant layer preform assembly.

5. The method for forming an irregularly shaped heat-resistant layer according to any one of claims 1-4, characterized in that, The pre-compression temperature of the first pre-compression treatment is 30℃~80℃. After the first pre-compression treatment, the pre-compressed heat-resistant layer blank is also trimmed.

6. The method for forming an irregularly shaped heat-resistant layer according to any one of claims 1-4, characterized in that, The pre-compression temperature of the second pre-compression treatment is 50℃~80℃, and the pressure of the second pre-compression treatment includes vacuum pressure and external pressure of 0.1Mpa~0.5Mpa.

7. The method for forming an irregularly shaped heat-resistant layer according to any one of claims 1-4, characterized in that, The row span of the through-stitch is 10mm to 50mm, and the column span is also 10mm to 50mm.

8. The method for forming an irregularly shaped heat-resistant layer according to any one of claims 1-4, characterized in that, The curing process is carried out using a stepped temperature method, with a curing temperature of 80℃~100℃ and a holding time of 6h~8h, and a curing temperature of 110℃~130℃ and a holding time of 3h~4h.

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