A method for forming a fiber-wound engine casing insulation layer

Abstract

This invention discloses a method for forming a fiber-wound engine casing insulation layer. The insulation layer includes an insulation reinforcement layer and an outer insulation layer. The insulation reinforcement layer includes an inner insulation layer and a middle carbon fiber reinforced insulation layer. The insulation reinforcement layer is parted at a starting point 100-200mm in the direction of the cylindrical section, extending towards the rear end, with an inclination angle of 15°-20°. The rear end insulation reinforcement layer and the cylindrical section insulation reinforcement layer adopt a flow-oriented structure and are overlapped with a bevel. The rear end insulation reinforcement layer and the cylindrical section insulation reinforcement layer also adopt a staggered layer structure. To meet the insulation layer requirements during engine operation, the parting of the cylindrical section and the rear end carbon fiber reinforced insulation layer is optimized. A molding process is used to ensure that the external dimensions of the cylindrical section carbon fiber reinforced insulation layer meet design requirements, achieving flow-oriented forming of the cylindrical section carbon fiber reinforced insulation layer.

Description

Technical Field

[0001] This invention relates to the field of fiber-wound solid rocket motor casings, and more specifically to a method for forming a heat insulation layer of a fiber-wound motor casing. Background Technology

[0002] The function of the inner insulation layer is to isolate the high-temperature gas flow generated by the combustion of the propellant grain during engine operation, thereby ensuring the strength and structural integrity of the engine casing. It is a key component for ensuring the normal operation of rocket engines. Currently, the main materials used for the inner insulation layer in China include nitrile rubber (9621) insulation material, EPDM insulation material, as well as erosion-resistant nitrile rubber (5-Ⅲ) insulation material, erosion-resistant EPDM insulation material, carbon fiber reinforced nitrile-phenolic material (5-VI) (viscose-based carbon fiber reinforced nitrile-phenolic material), T-1 (carbon fiber braided reinforced nitrile-phenolic material), etc.

[0003] Conventional solid rocket motors have low lateral overload, and erosion-resistant insulation materials are generally only used in the relatively harsh aft head region. In recent years, with the development of high-speed, high-overload, and high-performance tactical missiles, the requirements for the erosion resistance of insulation materials in the aft column section of solid rocket motors have gradually increased, in addition to the aft head region. Conventional methods of locally increasing the thickness of the insulation layer not only increase the negative mass of the motor but also reduce the shell volume, thereby reducing the propellant load and lowering the mass-to-weight ratio of the solid rocket motor.

[0004] To improve the ablation resistance of the rear column section of fiber-wound solid rocket motor casings, a sandwich structure combining erosion-resistant EPDM insulation and ordinary EPDM insulation is currently widely used. With advancements in materials technology, a fiber-reinforced insulation material has emerged that exhibits a low ablation rate and good structural integrity after combustion, making its application possible.

[0005] Currently, the molding process of fiber-reinforced insulation materials faces several challenges: 1. The use of a single C-shaped joint in the cylindrical section, limited by the part's external structure, results in significant discrepancies between the thickness, dimensions, and density of the molded parts produced using current airbag and autoclave molding methods and the designed dimensions (the fiber-reinforced insulation material produced by airbag molding is essentially twice the design size). 2. Subsequent fiber winding and pressurization alone cannot guarantee the internal density of the fiber-reinforced insulation material, and the outer diameter of the insulation layer often fails to meet design specifications. Machining processes can also compromise the material's integrity, thus affecting its performance. 3. Due to the difficulty in achieving precise dimensions for a single C-shaped fiber-reinforced insulation material in the cylindrical section, the insulation layer can only be fabricated using a reverse-flow structure with good workability, such as outer layer winding or silicone rubber heating and pressurization. While this structure offers better molding capabilities for the cylindrical section insulation layer, it is less conducive to maintaining the integrity of the insulation layer after ablation compared to a co-flow structure. Summary of the Invention

[0006] The purpose of this invention is to provide a method for forming a fiber-wound engine casing insulation layer to meet the erosion resistance requirements of the insulation layer under operating conditions. This method ensures that the external dimensions of the cylindrical carbon fiber reinforced insulation layer meet the design requirements and enables the forming of the cylindrical carbon fiber reinforced insulation layer with airflow.

[0007] To achieve the above objectives, the present invention provides a method for forming a fiber-wound engine casing insulation layer. The insulation layer includes an insulation reinforcement layer and an outer insulation layer. The insulation reinforcement layer includes an inner insulation layer and an intermediate carbon fiber reinforced insulation layer. The insulation reinforcement layer is formed by extending 100-200mm towards the cylinder section with the crack arrest point as the starting point and tilting towards the rear end cap, with an tilt angle of 15°-20°. The rear end cap insulation reinforcement layer and the cylinder section insulation reinforcement layer adopt a flow-oriented structure and are joined by a bevel. The rear end cap insulation reinforcement layer and the cylinder section insulation reinforcement layer adopt a staggered layer structure.

[0008] Furthermore, the molding method is as follows:

[0009] 1) Post-end forming

[0010] The bottom layer is formed by two vulcanization processes before the end cap is formed;

[0011] 2) Insulation layer forming

[0012] 2a) Polytetrafluoroethylene fiberglass tape is pasted on the curved surface of the core mold head, and polytetrafluoroethylene tape is wrapped around the column segment;

[0013] 2b) After attaching the raw rubber sheet to the front end of the mandrel and installing the front end onto the mandrel, check the distance between the front end and the rear end face of the mandrel to confirm that it is installed in place;

[0014] 2c) Apply raw rubber sheets to the core mold column section in a flow pattern to form an insulation layer inside the cylinder section;

[0015] 2d) Install carbon fiber reinforced insulation layer on the cylindrical section;

[0016] 2e) The rear end cap is connected to the insulation reinforcement layer of the cylinder section;

[0017] 2f) After testing, the height difference between the end cap opening and the insulation reinforcement layer of the cylinder section shall not exceed 1mm on one side, and the outer diameter shall not exceed the theoretical diameter + 2mm;

[0018] 2g) An outer layer of raw rubber sheet is bonded to the outer layer of the tube section insulation reinforcement layer and the rear end cap to form an outer insulation layer;

[0019] 2h) Use a polishing machine to polish the front and rear end caps, and use a patch machine to automatically polish the column sections until the external dimensions meet the process requirements.

[0020] Furthermore, the specific process of step 1) is as follows:

[0021] 1a) First-stage pre-vulcanization of the bottom layer

[0022] Metal joints are anodized and sandblasted, and raw rubber sheets are pasted after the interface is coated with adhesive. The inner insulation layer is pre-vulcanized for the first time during molding.

[0023] 1b) Secondary vulcanization of the bottom layer

[0024] The surface of the inner insulation layer is polished, raw rubber sheet is pasted on the surface, then the carbon fiber reinforced insulation material of the rear end is placed, and then the surface raw rubber sheet is pasted on for a second vulcanization to form the bottom layer.

[0025] 1c) Post-head forming

[0026] The bottom bonding area is sanded, the bottom layer is placed into the mold, a raw rubber sheet is pasted on the surface to make a cover layer, the upper mold is closed, vulcanization and demolding are performed to form the end cap.

[0027] Further, in step 2c), raw rubber sheets are pasted onto the core mold column section in a flow-oriented manner, with the overlapping joints of the raw rubber sheets staggered and the interference with the rear end of the core mold controlled axially; then, polytetrafluoroethylene (PTFE) tape is wrapped around the raw rubber sheets, and two layers of glass fiber yarn are wrapped around the surface of the PTFE tape. After the rubber sheet is cold-pressed and compacted, the fiber yarn and PTFE tape are removed. Before compaction, glass fiber cloth, carbon fiber cloth, or rubber tape is pasted on the steps and bevel surfaces to buffer fiber tension; after the rubber sheet is compacted, the overlapping positions are polished.

[0028] Furthermore, in step 2d), the cylindrical carbon fiber reinforced insulation layer is a circumferential rotating body with a thickness of 2-6 mm, and is formed by two circumferentially 180° semi-cylinders joined together; the two circumferentially 180° semi-cylinders are joined by a beveled joint, with an overlap width of not less than 10 mm and an angle of not more than 10°.

[0029] Further, in step 2d), adhesive is applied to the joint of the two circumferentially 180° semi-cylindrical carbon fiber reinforced insulation materials and allowed to dry, and a transition raw rubber sheet is pasted onto the joint surface; then, the overlap of the two circumferentially 180° semi-cylindrical carbon fiber reinforced insulation materials is placed at a position with minimal scouring in the inner insulation layer, and the interference with the rear end cap is controlled axially. During the pasting process of the two circumferentially 180° semi-cylindrical carbon fiber reinforced insulation materials, polytetrafluoroethylene tape and rubber bands are used for fixation; polytetrafluoroethylene tape is wrapped around the outer surface of the prepared insulation layer for protection, and simultaneously... Remove the PTFE tape and rubber rope used for fixing; use fiberglass cloth, carbon fiber cloth or rubber tape to attach to the steps and bevel surfaces to buffer fiber tension; then, longitudinally wrap one layer and circumferentially wrap two layers of fiberglass on the surface of the prepared carbon fiber reinforced insulation layer; finally, heat to 80-100℃ at 0.5-1℃ / min for 2-4 hours for pre-vulcanization treatment; after pre-vulcanization, grind and trim the circumferential overlap edge of the carbon fiber reinforced insulation layer and the mating surface with the rear end cap, so that the surface and outer diameter dimensions meet the process requirements.

[0030] Further, in step 2e), after applying adhesive to the mating surface of the rear end cap and the thermal insulation reinforcement layer of the cylinder section, the raw rubber sheet is pasted onto the mating surface of the rear end cap; the rear end cap is installed into the rear joint positioning fixture and then assembled with the core mold, and tightened with a clamping nut; the distance between the front and rear joints is checked to meet the process requirements; at the mating position of the rear end cap and the thermal insulation reinforcement layer of the cylinder section, polytetrafluoroethylene tape is wrapped around it, and two layers of glass fiber yarn are wrapped around the outer circumferentially and kept for 15-25 minutes before the glass fiber yarn is removed.

[0031] Further, in step 2g), an outer layer of raw rubber sheet is pasted onto the outer layer of the insulation reinforcement layer of the cylinder section and the outer layer of the rear end cap; polytetrafluoroethylene tape is wound around the surface of the outer layer of raw rubber sheet, a layer of glass fiber yarn is wound longitudinally, and two layers of glass fiber yarn are wound circumferentially, with a single strand tension of 30-60N; the temperature is raised to 80-100℃ at a heating rate of 0.5-1℃ / min and kept at the temperature for 2-4 hours to pre-vulcanize the outer layer of raw rubber.

[0032] Furthermore, a layer of raw rubber sheet is circumferentially pasted at the overlap position between the rear end cap and the thermal insulation reinforcement layer of the cylinder section.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows: while meeting the requirements for the use of the insulation layer during engine operation, by optimizing the parting of the cylindrical section and the rear end carbon fiber reinforced insulation layer, the external dimensions of the cylindrical section carbon fiber reinforced insulation layer meet the design requirements, and the flow-oriented forming of the cylindrical section carbon fiber reinforced insulation layer is realized. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the insulation layer type of the present invention. Detailed Implementation

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments to facilitate a clearer understanding of the invention, but these descriptions do not constitute a limitation on the invention.

[0036] The fiber-wound engine housing insulation layer of the present invention includes an insulation reinforcement layer and an outer insulation layer 5, such as... Figure 1 The thermal insulation reinforcement layer shown includes an inner thermal insulation layer and an intermediate carbon fiber reinforced thermal insulation layer. Since the molding process of the rear end cap is simpler than the manual patching process for the cylinder section, the thermal insulation reinforcement layer is parted as close to the molded rear end cap as possible, without exceeding the molding height limit. Specifically, the thermal insulation reinforcement layer is parted 100-200mm towards the cylinder section, starting from the crack arrest point and tilted towards the rear end cap at an angle of 15°-20°. The rear end thermal insulation reinforcement layer (inner rear end insulation layer 4 and intermediate rear end carbon fiber reinforced thermal insulation layer 1) and the cylinder section thermal insulation reinforcement layer (inner cylinder section insulation layer 2 and intermediate cylinder section carbon fiber reinforced thermal insulation layer 3) adopt a flow-oriented structure and a beveled overlap to increase the reliability of the thermal insulation reinforcement layer during operation. To ensure the effective thickness of the rear end and cylinder section thermal insulation reinforcement layers, a staggered layer structure is used.

[0037] The cylindrical carbon fiber reinforced insulation layer 3 used in this invention is a circumferential rotating body with a thickness of 2-6 mm, and is formed by two circumferentially 180° semi-cylinders joined together. In order to ensure the effective thickness of the cylindrical carbon fiber reinforced insulation layer at the overlapping position and to increase the bonding reliability at the overlapping position, the two circumferentially 180° semi-cylinders are overlapped with a beveled joint, and the overlap width is not less than 10 mm (angle not greater than 10°). In order to reduce the number of tooling processes, a circumferential butt joint structure is adopted, and only one set of tooling is needed to complete the processing of two identical parts.

[0038] The method for forming the fiber-wound engine housing insulation layer of the present invention includes the following steps:

[0039] 1) Post-end forming

[0040] 1a) First-stage pre-vulcanization of the bottom layer

[0041] Metal joints are anodized and sandblasted. After the interface is coated with adhesive (CH205 base adhesive + AE-2 top adhesive), raw rubber sheets are pasted on. After the first pre-vulcanization in the mold, the inner insulation layer of the head is applied.

[0042] 1b) Secondary vulcanization of the bottom layer

[0043] The surface of the inner insulation layer is polished after vulcanization, and a 0.5mm thick raw rubber sheet is pasted on the surface. Then, the carbon fiber reinforced insulation material of the rear end is placed, and the surface raw rubber sheet is pasted on again for a second vulcanization to form the bottom layer. AE-4 adhesive is used at the rubber raw / cured interface, and AE-3 adhesive is used for the rubber raw / carbon fiber reinforced insulation material. In order to control the position of the carbon fiber reinforced insulation material of the rear end, the bottom layer of the rear end is formed by two vulcanization processes.

[0044] 1c) Post-head forming

[0045] The bottom bonding area is sanded, the bottom layer is placed into the mold, a raw rubber sheet is pasted on the surface to make a cover layer, the upper mold is closed and vulcanized to demold and form the end cap. AE-4 adhesive is used at the rubber raw / cured interface.

[0046] 2) Molding of 180° circumferential semi-cylindrical carbon fiber reinforced thermal insulation material

[0047] Currently, carbon fiber reinforced thermal insulation materials mainly include viscose-based chopped carbon fibers and nitrile-phenolic resin premixes, as well as T300 and T700 3K-12K carbon fiber braids vacuum-impregnated with nitrile-phenolic resin. To ensure the internal quality and dimensional requirements of the product, this invention employs a compression molding process. To give the cylindrical fiber-reinforced thermal insulation material good flexibility and good bonding performance (it can be used directly after applying adhesive without sanding), a pre-cured state (incomplete curing) is used. The molding process is as follows;

[0048] 2a) Premix system preparation process: Viscose-based short carbon fiber cutting → acrylonitrile-phenolic resin preparation → fiber impregnation → air drying → loosening → drying;

[0049] Carbon fiber weaving system preparation process: skeleton weft knitting (two-and-a-half, three-dimensional) structure → nitrile-phenolic resin preparation → vacuum impregnation → air drying → drying;

[0050] 2b) Weigh the material according to the process requirements, and then pre-cur it to obtain the cylindrical carbon fiber reinforced thermal insulation material: the pre-curing temperature is 90℃~120℃, the pre-curing pressure is 2~7Mpa, and the pre-curing time is 2~hours.

[0051] 3) Insulation layer forming

[0052] 3a) Polytetrafluoroethylene fiberglass tape is pasted on the curved surface of the core mold head, and polytetrafluoroethylene tape is wrapped around the column segment;

[0053] 3b) After attaching the raw rubber sheet to the front end of the mandrel and installing the front end onto the mandrel, check the distance between the front end and the rear end face of the mandrel to confirm that it is installed in place; use AE-4 for raw / cooked interface and AE-1 for raw / uncooked interface;

[0054] 3c) Adhere raw rubber sheets to the core mold column section in a flow pattern, with the overlaps of the raw rubber sheets staggered by 50-100mm, and control the axial interference with the rear end of the core mold by 1-3mm; then wrap PTFE tape around the raw rubber sheets (to protect the sheets from contamination), and wrap two layers of glass fiber yarn (single strand tension 30-60N) around the surface of the PTFE tape and keep it for 15-25 minutes. After cold pressing the sheets, remove the fiber yarn and PTFE tape. Before pressing, use glass fiber cloth, carbon fiber cloth, or rubber tape to adhere to the steps and bevel surfaces to buffer fiber tension; after the sheets are pressed, grind the overlap areas to maintain a good profile at the molding position, which is beneficial to improving the quality of the insulation layer and ensuring the outer diameter dimensions;

[0055] 3d) Apply AE-3 adhesive to the joint of the two circumferentially 180° semi-cylindrical carbon fiber reinforced insulation materials and let it dry. Then, attach a transition raw rubber sheet to the joint surface. Next, place the overlap of the two circumferentially 180° semi-cylindrical carbon fiber reinforced insulation materials at a location with minimal scouring in the inner insulation layer, controlling the axial interference with the back end cap to be 1-3 mm. Use PTFE tape and rubber bands for fixation during the bonding process. Wrap PTFE tape around the outer surface of the prepared insulation layer for protection, and remove the tape used for fixing. Polytetrafluoroethylene tape and rubber rope are used; fiberglass cloth, carbon fiber cloth or rubber tape are pasted on the steps and bevel surfaces to buffer fiber tension; then, one layer of fiberglass is wound longitudinally and two layers of fiberglass are wound circumferentially on the surface of the prepared carbon fiber reinforced insulation layer (single strand tension is 30-60N); finally, the temperature is raised to 80-100℃ at 0.5-1℃ / min and heated for 2-4 hours for pre-vulcanization treatment; after pre-vulcanization, the circumferential overlap edge of the carbon fiber reinforced insulation layer and the mating surface with the rear end cap are polished and repaired, and the surface and outer diameter dimensions meet the process requirements.

[0056] 3e) Apply AE-4 (raw / cooked interface) and AE-3 (raw / carbon fiber reinforced insulation layer interface) adhesives to the mating surface of the rear end cap and the insulation reinforcement layer of the cylindrical section. Then, attach a 0.5mm raw rubber sheet to the mating surface of the rear end cap. Install the rear end cap into the rear joint positioning fixture and then fit it together with the mandrel. Tighten the clamping nut. Check the distance between the front and rear joints to ensure it meets the process requirements. Wrap polytetrafluoroethylene tape around the mating position of the rear end cap and the insulation reinforcement layer of the cylindrical section. Wrap two layers of glass fiber yarn (single strand tension 30-60N) around the outer circumferentially. After keeping it for 15-25 minutes, remove the glass fiber yarn.

[0057] 3f) After testing, the height difference between the end cap opening and the insulation reinforcement layer of the cylinder section shall not exceed 1mm on one side, and the outer diameter shall not exceed the theoretical diameter + 2mm;

[0058] 3g) The outer layer of raw rubber sheet is pasted on the outer layer of the insulation reinforcement layer of the cylinder section and the outer layer of the rear end cap to form the outer insulation layer 6. The raw / raw interface uses AE-1, AE-4 (raw / cure interface), and AE-3 (raw / composite layer interface). Polytetrafluoroethylene tape is wrapped around the surface of the outer raw rubber sheet, one layer of glass fiber yarn is wound longitudinally, and two layers of glass fiber yarn are wound circumferentially. The tension of a single strand of yarn is 30-60N. The temperature is raised to 80-100℃ at a heating rate of 0.5-1℃ / min and held for 2-4 hours to pre-vulcanize the outer raw rubber.

[0059] 3h) Use a polishing machine to polish the front and rear end caps, and use a patch machine to automatically polish the column sections until the external dimensions meet the process requirements.

[0060] To ensure the thickness of the outer insulation layer 5 at the joint between the cylinder section and the rear end cap, a layer of raw rubber sheet is circumferentially pasted at the overlap of the insulation reinforcement layer between the rear end cap and the cylinder section.

[0061] To meet the requirements of the insulation layer during engine operation, the parting of the carbon fiber reinforced insulation layer between the cylindrical section and the rear end cap was optimized. The molding process was adopted to ensure that the external dimensions of the carbon fiber reinforced insulation layer of the cylindrical section met the design requirements, and the airflow forming of the carbon fiber reinforced insulation layer with the cylindrical section was realized.

[0062] The carbon fiber reinforced insulation material of the cylindrical section is circumferentially overlapped, and both the cylindrical section and the rear end cap are overlapped with beveled edges and staggered layers. This ensures that the carbon fiber reinforced insulation material has an effective thickness and good molding process performance. The overlap position is transitioned by insulation rubber with good flowability and a certain filling function. By controlling the interference of 1-3mm between the insulation rubber of the cylindrical section and the fiber reinforced insulation material of the cylindrical section and the rear end cap, the interface bonding quality is ensured.

[0063] During the fabrication of the insulation layer, the fabrication proceeds from the front end cap to the rear end cap, maintaining a flow-oriented structure. Fiber cold pressing and hot pressing processes are employed, and buffer materials are used to pad the bevel positions to ensure the surface quality and the internal forming quality of the insulation layer.

Claims

1. A method for forming a fiber-wound engine housing insulation layer, characterized in that: The insulation layer includes an insulation reinforcement layer and an outer insulation layer. The insulation reinforcement layer includes an inner insulation layer and an intermediate carbon fiber reinforced insulation layer. Starting from the crack arrest point, extend 100-200mm towards the cylinder section and tilt towards the rear head to form a type of thermal insulation reinforcement layer with an inclination angle of 15°-20°. The thermal insulation reinforcement layer of the rear head and the thermal insulation reinforcement layer of the cylinder section adopt a flow-oriented structure and are joined by a bevel. The thermal insulation reinforcement layer of the rear head and the thermal insulation reinforcement layer of the cylinder section adopt a staggered structure. The molding method is as follows: 1) Rear end forming The bottom layer is formed by two vulcanization processes before the end cap is formed; 2) Insulation layer forming 2a) Polytetrafluoroethylene fiberglass tape is pasted on the curved surface of the core mold head, and polytetrafluoroethylene tape is wrapped around the column segment; 2b) After attaching the raw rubber sheet to the front end of the mandrel and installing the front end onto the mandrel, check the distance between the front end and the rear end face of the mandrel to confirm that it is installed in place; 2c) Apply raw rubber sheets to the core mold column section in a flow pattern to form an insulation layer inside the cylinder section; 2d) Install carbon fiber reinforced insulation layer on the cylindrical section; 2e) The rear end cap is connected to the insulation reinforcement layer of the cylinder section; 2f) After testing, the height difference between the end cap opening and the insulation reinforcement layer of the cylinder section shall not exceed 1 mm on one side, and the outer diameter shall not exceed the theoretical diameter + 2 mm; 2g) An outer layer of raw rubber sheet is bonded to the outer layer of the tube section insulation reinforcement layer and the rear end cap to form an outer insulation layer; 2h) Use a polishing machine to polish the front and rear end caps, and use a patch machine to automatically polish the column sections until the external dimensions meet the process requirements.

2. The method for forming the fiber-wound engine housing insulation layer according to claim 1, characterized in that: The specific process of step 1) is as follows: 1a) First-stage pre-vulcanization of the bottom layer Metal joints are anodized and sandblasted, and raw rubber sheets are pasted after the interface is coated with adhesive. The inner insulation layer is pre-vulcanized for the first time during molding. 1b) Secondary vulcanization of the bottom layer The surface of the inner insulation layer is polished, raw rubber sheet is pasted on the surface, then the carbon fiber reinforced insulation material of the rear end is placed, and then the surface raw rubber sheet is pasted on for a second vulcanization to form the bottom layer. 1c) Post-head forming The bottom bonding area is sanded, the bottom layer is placed into the mold, a raw rubber sheet is pasted on the surface to make a cover layer, the upper mold is closed, vulcanization and demolding are performed to form the end cap.

3. The method for forming the fiber-wound engine housing insulation layer according to claim 1, characterized in that: In step 2c), raw rubber sheets are pasted onto the core mold column section in a flow pattern, with the overlapping joints of the raw rubber sheets staggered and the axial interference with the rear end of the core mold controlled; then, polytetrafluoroethylene (PTFE) tape is wrapped around the raw rubber sheets, and two layers of glass fiber yarn are wrapped around the surface of the PTFE tape. After the rubber sheets are cold-pressed and compacted, the fiber yarn and PTFE tape are removed. Before compaction, glass fiber cloth, carbon fiber cloth, or rubber tape is pasted on the steps and bevel surfaces to buffer fiber tension; after the rubber sheets are compacted, the overlapping positions are polished.

4. The method for forming the fiber-wound engine housing insulation layer according to claim 1, characterized in that: In step 2d), the cylindrical carbon fiber reinforced insulation layer is a circumferential rotating body with a thickness of 2~6mm, which is formed by two circumferentially 180° semi-cylinders joined together; the two circumferentially 180° semi-cylinders are joined by a beveled joint, with an overlap width of not less than 10mm and an angle of not more than 10°.

5. The method for forming the fiber-wound engine housing insulation layer according to claim 1, characterized in that: In step 2d), adhesive is applied to the joint of the two circumferentially 180° semi-cylindrical carbon fiber reinforced insulation materials and allowed to dry. A transition raw rubber sheet is then pasted onto the joint surface. Next, the overlap of the two circumferentially 180° semi-cylindrical carbon fiber reinforced insulation materials is placed at a location with minimal scouring in the inner insulation layer. The axial interference with the rear end cap is controlled. During the pasting process, PTFE tape and rubber bands are used for fixation. PTFE tape is then wrapped around the outer surface of the prepared insulation layer for protection, while simultaneously removing… The polytetrafluoroethylene tape and rubber rope used for fixing are used; glass fiber cloth, carbon fiber cloth or rubber tape are pasted on the steps and bevel surfaces to buffer fiber tension; then, one layer of glass fiber is wound longitudinally and two layers are wound circumferentially on the surface of the prepared carbon fiber reinforced insulation layer; finally, the temperature is raised to 80~100℃ at 0.5~1℃ / min and heated for 2~4 hours for pre-vulcanization treatment; after pre-vulcanization, the circumferential overlap edge of the carbon fiber reinforced insulation layer and the mating surface with the rear end cap are polished and repaired, and the surface and outer diameter dimensions meet the process requirements.

6. The method for forming the fiber-wound engine housing insulation layer according to claim 1, characterized in that: In step 2e), after applying adhesive to the mating surface of the rear end cap and the thermal insulation reinforcement layer of the cylinder section, the raw rubber sheet is pasted onto the mating surface of the rear end cap; the rear end cap is installed into the rear joint positioning fixture and then assembled with the core mold, and tightened with the clamping nut; the distance between the front and rear joints is checked to meet the process requirements; at the mating position of the rear end cap and the thermal insulation reinforcement layer of the cylinder section, polytetrafluoroethylene tape is wrapped around it, and two layers of glass fiber yarn are wrapped around the outer circumferentially and kept for 15-25 minutes before the glass fiber yarn is removed.

7. The method for forming the fiber-wound engine housing insulation layer according to claim 1, characterized in that: In step 2g), an outer layer of raw rubber sheet is pasted onto the outer layer of the insulation reinforcement layer of the cylinder section and the outer layer of the rear end cap; yarn is wound around the surface of the outer layer of raw rubber sheet, with a single strand tension of 30~60N; the temperature is raised to the polytetrafluoroethylene tape at a heating rate of 0.5~1℃ / min, a layer of glass fiber yarn is wound longitudinally, and two layers of glass fiber are wound circumferentially at 80~100℃, and the temperature is maintained for 2~4 hours to pre-vulcanize the outer layer of raw rubber.

8. The method for forming the fiber-wound engine housing insulation layer according to claim 7, characterized in that: The tension of the single yarn is 30~60N.

9. The method for forming the fiber-wound engine housing insulation layer according to claim 1, characterized in that: A layer of raw rubber sheet is circumferentially pasted at the overlap position between the rear end cap and the thermal insulation reinforcement layer of the cylinder section.

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