Multifunctional integrated heat-resistant skirt based on zoned variable density stitching

Abstract

This invention provides a multifunctional integrated heat-resistant skirt based on partitioned variable-density stitching, comprising: a heat-resistant skirt body and stitching threads; the stitching threads form high-density stitching areas, medium-density stitching areas, and low-density or seamless stitching areas on the heat-resistant skirt body, achieving the effects of improving interlayer shear strength and peel strength, suppressing surface instability, and extending service life. A high-density stitching area is set around the bolt connection holes to form a locally reinforced area, dispersing stress concentration around the connection holes, thereby improving the load-bearing capacity of the connection points and reducing the risk of local failure; by setting a low-density or seamless stitching area in the swing deformation area, the flexibility of this area is preserved. This invention solves the problem that existing lamination and bonding schemes cannot achieve integrated connection of multiple functional layers, achieving the effect of balancing the reinforcement of the connection area, the integrity of the main body area, and the flexibility of the swing area.

Description

Technical Field

[0001] This invention relates to the field of rocket structural component design and manufacturing technology, specifically to a multifunctional integrated heat-resistant skirt based on partitioned variable density stitching. Background Technology

[0002] A Chinese patent with publication number CN107662715A discloses an ablation-resistant, high-barrier flexible heat-resistant skirt and its preparation method. It consists of several layers of flexible ablation-resistant layers, several layers of flexible radiation-resistant layers, and a flexible high-barrier layer. The flexible ablation-resistant layers and flexible radiation-resistant layers are alternately distributed from the outside to the inside in an SFSF-…-SF structure, where S is the flexible ablation-resistant layer, F is the flexible radiation-resistant layer, and the flexible high-barrier layer is located on the innermost side. The flexible ablation-resistant layers, flexible radiation-resistant layers, and flexible high-barrier layers are bonded together at the nozzle mounting point using silicone rubber adhesive. This invention uses an alternating arrangement of flexible ablation-resistant layers and flexible radiation-resistant layers in the outer layer, fully utilizing the synergistic effect between them. Furthermore, the flexible ablation-resistant layer uses a phenolic resin-modified silicone rubber system, further improving its ablation resistance. While ensuring ablation resistance, it effectively reduces the overall thickness of the skirt, with an overall thickness reduction of 1 / 2 to 2 / 3 compared to existing structures.

[0003] However, in the ablation-resistant, high-barrier flexible heat-resistant skirt and its preparation method, the interlayer relies on adhesive bonding or vulcanization interfaces, which are prone to aging and failure under high-temperature swing conditions, leading to delamination; it is impossible to achieve mechanical integration of multiple functional layers; and there are no reinforcement measures around the connection holes, so the stress concentration problem remains unresolved. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a multifunctional integrated heat-resistant skirt based on partitioned variable density stitching.

[0005] According to the present invention, a multifunctional integrated heat-resistant skirt based on partitioned variable density stitching includes: a heat-resistant skirt body and stitching threads; The heat-resistant skirt body includes an ablation layer, a heat insulation layer, a load-bearing layer, and a sealing layer stacked sequentially from the outside to the inside; The stitching lines are sewn onto the heat-resistant skirt body to form high-density stitching areas, medium-density stitching areas, low-density or seamless stitching areas; The high-density stitching area is located around the bolt connection holes of the heat-resistant skirt body. The stitches in the high-density stitching area stitch the ablation layer, heat insulation layer, load-bearing layer and sealing layer into one piece. The stitch density of the stitches in the high-density stitching area is 20 to 40 stitches / 100mm, and the stitching direction is a combination of circumferential and radial mesh stitching. The medium-density stitching area is located in the circumferential connection area of ​​the heat-insulating skirt body. The stitches in the medium-density stitching area stitch at least two of the ablation layer, heat insulation layer, load-bearing layer and sealing layer into one piece. The stitch density of the stitches in the medium-density stitching area is 10 to 20 stitches / 100mm, and the stitching direction is circumferential stitching, axial stitching or mesh stitching. The low-density or seamless area is provided in the main body area of ​​the heat-insulating skirt body. The stitches in the low-density or seamless area stitch up to two of the ablation layer, heat insulation layer, load-bearing layer and sealing layer into one piece. The stitch density in the low-density or seamless area is 0 to 10 stitches / 100mm, and the stitching direction is circumferential stitching, axial stitching or mesh stitching, or no stitching at all.

[0006] Preferably, the stitching is made on the heat-resistant skirt body using a velvet stitching process. The velvet stitching process uses a single needle and single thread, with no bends or interlocking loops in the stitching, and the maximum stitchable thickness is 40mm.

[0007] Preferably, the stitching is done using a blind stitching process on the heat-resistant skirt body, and the blind stitching process uses a crescent-shaped circular needle to drive the stitching movement.

[0008] Preferably, the ablation layer is made of phenolic resin modified silicone rubber coated fiber fabric or ultra-high temperature flame retardant silicone rubber coated cloth. The insulation layer is made of flexible insulation felt; The load-bearing layer is made of high-strength Kevlar fiber fabric reinforced composite material; The sealing layer is made of silicone rubber coated fabric or fluororubber coated fabric.

[0009] Preferably, the diameter of the suture is no greater than 0.5 mm.

[0010] Preferably, the suture material is selected from one of poly(p-phenylenebenzodioxazole) fiber, Kevlar fiber, carbon fiber, or quartz glass fiber.

[0011] Preferably, the surface of the suture is treated with a surface coupling agent.

[0012] Preferably, the multifunctional integrated heat-resistant skirt based on partitioned variable density stitching is fixed to the engine nozzle flange by an inner pressure plate, an outer pressure plate, and bolts in conjunction with the bolt connection holes.

[0013] Preferably, positioning marks are provided on the ablation layer, heat insulation layer, load-bearing layer and sealing layer respectively. The ablation layer, heat insulation layer, load-bearing layer and sealing layer are aligned with the positioning marks on each layer and then sutured using the high-density suture area, medium-density suture area and low-density or seamless suture area of ​​the suture thread.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention integrates separate functional layers such as the ablation layer, heat insulation layer, load-bearing layer, and sealing layer into a whole by adopting a partitioned variable density stitching structure including a high-density stitching area, a medium-density stitching area, and a low-density or seamless stitching area. This solves the problems of poor structural integrity, easy relative slippage between layers, and easy wrinkling and abnormal friction caused by the lack of interlayer bonding in existing heat protection skirts. It achieves the effects of improving the interlayer shear strength and peel strength, suppressing surface instability, and extending service life. 2. This invention creates a localized reinforced area by setting a high-density stitching zone around the bolt connection hole, thereby dispersing the stress concentration around the connection hole. This solves the problem that existing heat protection skirts are prone to damage under cyclic loads due to significant stress concentration at the hole edges caused by dense bolt connections. It achieves the effect of improving the load-bearing capacity of the connection point and reducing the risk of local failure. 3. This invention preserves the flexibility of the swing deformation area by setting a low-density or seamless bonding area. This solves the problem that existing lamination and bonding methods cannot achieve integrated connection of multiple functional layers, achieving a balance between strengthening the connection area, maintaining the integrity of the main body area, and ensuring the flexibility of the swing area. 4. This invention, by employing a felt-like stitching or blind stitching process, achieves the goal of eliminating interlocking loops in the sutures or leaving the stitches inside the layers. It also selects sutures with a diameter of no more than 0.5 mm, which solves the problems of traditional suture processes such as significant damage to the inner fibers, easy introduction of stress concentration, and the potential formation of heat flow short-circuit channels by needle holes. This achieves the effect of maximizing the protection of the integrity of the inner fibers and avoiding the deterioration of thermal protection performance while improving the interlayer bonding strength. Attached Figure Description

[0015] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the structure of the heat-resistant skirt body, which mainly embodies the multifunctional integrated heat-resistant skirt based on partitioned variable density stitching, according to the present invention. Figure 2 This is a schematic diagram illustrating the stitching of a multifunctional integrated heat-resistant skirt based on partitioned variable density stitching, which is the main feature of this invention. Figure 3 This is a schematic diagram illustrating the principle of the pile stitching method, which is the main feature of this invention. Figure 4 This is a schematic diagram illustrating the principle of the blind stitching method, which is the main feature of this invention.

[0016] The diagram shows: 1. Ablation layer; 2. Insulation layer; 3. Load-bearing layer; 4. Sealing layer; 5. Suture line; 6. Bolt connection hole; 7. High-density suture area; 8. Medium-density suture area; 9. Low-density or seamless suture area; 10. Circumferential suture line; 11. Longitudinal suture line. Detailed Implementation

[0017] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0018] like Figure 1 As shown, a multifunctional integrated heat-resistant skirt based on partitioned variable density stitching according to the present invention includes: a heat-resistant skirt body and stitching thread 5.

[0019] The heat-resistant skirt body comprises, from the outside in, an ablation layer 1, a heat insulation layer 2, a load-bearing layer 3, and a sealing layer 4, stacked sequentially. Specifically, the ablation layer 1 is located on the outermost layer and is made of phenolic resin-modified silicone rubber coated fiber fabric or ultra-high temperature flame-retardant silicone rubber coated cloth. The heat insulation layer 2 is located inside the ablation layer 1 and is used to block heat transfer to the interior, using flexible heat insulation felt. The load-bearing layer 3 is located inside the heat insulation layer 2 and is used to withstand aerodynamic loads and connection loads, using high-strength Kevlar fiber fabric reinforced composite material. The sealing layer 4 is located on the innermost layer and is used to achieve an airtight seal, using silicone rubber coated fabric or fluororubber coated fabric.

[0020] The stitching 5 selectively stitches the ablation layer 1, the heat insulation layer 2, the load-bearing layer 3, and the sealing layer 4 on the heat-insulating skirt body, either in full or as a subsystem. Combined with circumferential, axial, or mesh stitching directions, it forms a high-density stitching area 7, a medium-density stitching area 8, and a low-density or seamless stitching area 9.

[0021] The high-density stitching area 7 is located around the bolt connection holes 6 of the heat-insulating skirt body. The stitches 5 of the high-density stitching area 7 stitch the ablation layer 1, the heat insulation layer 2, the load-bearing layer 3, and the sealing layer 4 into one piece. The stitch density of the stitches 5 in the high-density stitching area 7 is 20-40 stitches / 100mm, and the stitching direction is a combination of circumferential and radial mesh stitching. Figure 2 The diagram shows the circumferential suture 10 and the longitudinal suture 11.

[0022] The medium-density stitching area 8 is located in the circumferential connection area of ​​the heat-insulating skirt body. The two heat-insulating skirt bodies are connected in their own circumferential connection area. The stitches 5 of the medium-density stitching area 8 stitch at least two of the ablation layer 1, the heat insulation layer 2, the load-bearing layer 3, and the sealing layer 4 into one piece. The stitch density of the stitches 5 in the medium-density stitching area 8 is 10-20 stitches / 100mm, and the stitching direction is circumferential stitching, axial stitching, or mesh stitching.

[0023] A low-density or seamless area 9 is provided in the main body area of ​​the heat-resistant skirt body, which corresponds to the area of ​​engine nozzle oscillation and deformation. The stitches 5 of the low-density or seamless area 9 stitch up to two of the ablation layer 1, heat insulation layer 2, load-bearing layer 3, and sealing layer 4 into one piece. The stitch density of the stitches 5 in the low-density or seamless area 9 is 0 to 10 stitches / 100mm, and the stitching direction is circumferential stitching, axial stitching, mesh stitching, or no stitching at all.

[0024] The ablation layer 1, heat insulation layer 2, load-bearing layer 3, and sealing layer 4 are stacked in a predetermined order and placed on the sewing fixture, with the positioning marks of each layer aligned.

[0025] The area surrounding the pre-drilled bolt connection holes 6 of the heat-resistant skirt body is designated as a high-density stitching area 7, the circumferential connection area of ​​the heat-resistant skirt body itself is designated as a medium-density stitching area 8, and the main body area of ​​the heat-resistant skirt body is designated as a low-density or seamless stitching area 9.

[0026] According to the pre-set zoned stitching layout, using either a felt-like stitching technique or a blind stitching technique, suture thread 5 is used to sew the high-density stitching area 7 with a stitch density of 20-40 stitches / 100mm and a combination of circumferential and radial mesh stitching. Suture thread 5 is used to sew the medium-density stitching area 8 with a stitch density of 10-20 stitches / 100mm and a stitching direction of circumferential, axial, or mesh stitching. Suture thread 5 is used to sew the low-density / seamless area 9 with a stitch density of 0-10 stitches / 100mm and a stitching direction of circumferential, axial, or mesh stitching, or the area may be left unstitched.

[0027] Bolt connection holes 6 are made on the multi-functional integrated heat protection skirt based on partitioned variable density stitching after the stitching is completed. The bolt connection holes 6 are located within the high density stitching area 7. The heat protection skirt is fixed to the engine nozzle flange by the inner pressure plate, the outer pressure plate and bolts. When the engine nozzle swings, the heat protection skirt swings within a range of ±8° with the nozzle. The low-density / seamless stitching zone 9 provides sufficient flexibility to adapt to deformation. The high-density stitching zone 7 and the medium-density stitching zone 8 suppress the relative slippage and delamination between the functional layers, prevent wrinkles and abnormal friction, and ensure thermal protection performance and structural integrity.

[0028] The non-adhesive multilayer fabric composite structure is integrated through stitching, which solves the comprehensive optimization of integrity, connection reliability and swing adaptability.

[0029] By adopting a partitioned variable density stitching structure including a high-density stitching area 7, a medium-density stitching area 8, and a low-density or seamless stitching area 9, the separate functional layers such as the ablation layer 1, the heat insulation layer 2, the load-bearing layer 3, and the sealing layer 4 are integrated into a whole. This solves the problems of poor structural integrity, easy relative slippage between layers, and easy wrinkling and abnormal friction caused by the lack of interlayer bonding in the current heat protection skirt. It achieves the effects of improving the interlayer shear strength and peel strength, suppressing surface instability, and extending service life.

[0030] A high-density stitching area 7 is set around the bolt connection hole to form a local reinforcement area, which disperses the stress concentration around the connection hole. This solves the problem that the existing heat protection skirt is prone to damage and failure under cyclic load due to significant stress concentration at the hole edge caused by dense bolt connections. It achieves the effect of improving the load-bearing capacity of the connection point and reducing the risk of local failure.

[0031] A low-density or seamless bonding zone 9 is set in the swing deformation area to retain the flexibility of the area. This solves the problem that existing lamination and bonding schemes cannot achieve integrated connection of multiple functional layers, and achieves the effect of balancing the strengthening of the connection area, the integrity of the main body area and the flexibility of the swing area.

[0032] In one feasible implementation, the stitch 5 is sewn onto the heat-resistant skirt body using a velvet stitching process. The velvet stitching process uses a single needle and single thread, with no bends or interlocking loops in the stitch, and the maximum sewing thickness can reach 40mm.

[0033] In one feasible implementation, the suture 5 is made using a blind stitch technique on the heat-insulating skirt body. The blind stitch technique uses a crescent-shaped circular needle to drive the suture movement, so as to achieve a non-permeable suture where the stitches remain inside the layers.

[0034] In one feasible implementation, the diameter of the suture 5 is no greater than 0.5 mm to minimize puncture damage to the functional layer fibers, thus solving the problems of large damage to the inner fibers, easy introduction of stress concentration, and the possibility of heat flow short circuit channels formed by needle holes in traditional suturing processes.

[0035] This achieves the effect of improving the interlayer bonding strength while maximizing the protection of the integrity of the in-plane fibers and avoiding the deterioration of thermal protection performance.

[0036] In one feasible implementation, the material of the suture 5 is selected from one of poly(p-phenylenebenzodioxazole) fiber, Kevlar fiber, carbon fiber, or quartz glass fiber.

[0037] In one feasible implementation, the surface of the suture 5 is treated with a surface coupling agent to enhance interfacial bonding with the substrate of each functional layer.

[0038] In one feasible implementation, the multifunctional integrated heat-resistant skirt based on partitioned variable density stitching is fixed to the engine nozzle flange by an inner pressure plate, an outer pressure plate, and bolts connecting to bolt holes 6.

[0039] In one feasible implementation, positioning marks are respectively provided on the ablation layer 1, the heat insulation layer 2, the load-bearing layer 3, and the sealing layer 4. The ablation layer 1, the heat insulation layer 2, the load-bearing layer 3, and the sealing layer 4 are aligned with the positioning marks on each layer, and then sutured using sutures 5 in the high-density suture area 7, the medium-density suture area 8, and the low-density or seamless suture area 9.

[0040] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0041] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A multifunctional integrated heat-resistant skirt based on partitioned variable density stitching, characterized in that, include: Heatproof skirt body and seams (5); The heat-resistant skirt body includes an ablation layer (1), a heat insulation layer (2), a load-bearing layer (3), and a sealing layer (4) stacked sequentially from the outside to the inside. The stitching (5) forms a high-density stitching area (7), a medium-density stitching area (8), and a low-density or seamless stitching area (9) on the heat-resistant skirt body. The high-density stitching area (7) is located around the bolt connection hole (6) of the heat-insulating skirt body. The stitching line (5) of the high-density stitching area (7) stitches the ablation layer (1), the heat insulation layer (2), the load-bearing layer (3) and the sealing layer (4) into one piece. The stitching density of the stitching line (5) in the high-density stitching area (7) is 20 to 40 stitches / 100mm, and the stitching direction is a combination of circumferential and radial mesh stitching. The medium-density stitching area (8) is located in the circumferential connection area of ​​the heat-insulating skirt body. The stitches (5) of the medium-density stitching area (8) stitch at least two of the ablation layer (1), heat insulation layer (2), bearing layer (3) and sealing layer (4) into one piece. The stitch density of the stitches (5) in the medium-density stitching area (8) is 10 to 20 stitches / 100mm, and the stitching direction is circumferential stitching, axial stitching or mesh stitching. The low-density or seamless area (9) is provided in the main body area of ​​the heat-insulating skirt body. The stitches (5) of the low-density or seamless area (9) stitch up to two of the ablation layer (1), heat insulation layer (2), bearing layer (3) and sealing layer (4) into one piece. The stitch density of the stitches (5) in the low-density or seamless area (9) is 0 to 10 stitches / 100mm, and the stitching direction is circumferential stitching, axial stitching or mesh stitching, or no stitching at all.

2. The multifunctional integrated heat-resistant skirt based on partitioned variable density stitching as described in claim 1, characterized in that, The stitching thread (5) is stitched on the heat-resistant skirt body using a velvet stitching process. The velvet stitching process uses a single needle and single thread method, with no bending or interlocking loops in the stitching thread, and the maximum stitchable thickness is 40mm.

3. The multifunctional integrated heat-resistant skirt based on partitioned variable density stitching as described in claim 1, characterized in that, The stitching (5) is made using a blind stitching process on the heat-resistant skirt body, and the blind stitching process uses a crescent-shaped circular needle to push the stitching line.

4. The multifunctional integrated heat-resistant skirt based on partitioned variable density stitching as described in claim 1, characterized in that, The ablation layer (1) is made of phenolic resin modified silicone rubber coated fiber fabric or ultra-high temperature flame retardant silicone rubber coated cloth. The insulation layer (2) is made of flexible insulation felt; The supporting layer (3) is made of high-strength Kevlar fiber fabric reinforced composite material; The sealing layer (4) is made of silicone rubber coated fabric or fluororubber coated fabric.

5. The multifunctional integrated heat-resistant skirt based on partitioned variable density stitching as described in claim 1, characterized in that, The diameter of the suture (5) is no greater than 0.5 mm.

6. The multifunctional integrated heat-resistant skirt based on partitioned variable density stitching as described in claim 1, characterized in that, The material of the suture (5) is selected from one of poly(p-phenylenebenzodioxazole) fiber, Kevlar fiber, carbon fiber or quartz glass fiber.

7. The multifunctional integrated heat-resistant skirt based on partitioned variable density stitching as described in claim 6, characterized in that, The surface of the suture (5) is treated with a surface coupling agent.

8. The multifunctional integrated heat-resistant skirt based on partitioned variable density stitching as described in claim 1, characterized in that, The multifunctional integrated heat-resistant skirt based on partitioned variable density stitching is fixed to the engine nozzle flange by the inner pressure plate, the outer pressure plate and the bolts in conjunction with the bolt connection hole (6).

9. The multifunctional integrated heat-resistant skirt based on partitioned variable density stitching as described in claim 1, characterized in that, Positioning marks are provided on the ablation layer (1), heat insulation layer (2), bearing layer (3), and sealing layer (4). The ablation layer (1), heat insulation layer (2), bearing layer (3), and sealing layer (4) are aligned with the positioning marks on each layer, and then the sutures (5) are used to suture the high-density suture area (7), medium-density suture area (8), and low-density or seamless suture area (9).

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