A multi-stage pressure and temperature control forming method for an ablation-resistant missile engine shell

Abstract

This invention discloses a multi-stage pressure- and temperature-controlled molding method for ablation-resistant missile engine casing, within the field of missile engine combustion chamber technology. The method includes the following steps: S1: Tooling and mandrel pretreatment: Cleaning and defect inspection of the mandrel for mold placement, and treating the mandrel with a release agent; S2: Metal liner surface treatment: Grinding and cleaning the outer surface of the metal liner; S3: Applying epoxy film: Applying an epoxy film to the treated outer surface of the metal liner. This invention, through meticulous pretreatment of the tooling and mandrel, grinding and cleaning of the metal liner, and precise application of the epoxy film, combined with a multi-layer intermediate compaction process during composite material winding, effectively improves the interlayer bonding strength between the metal liner and the composite material winding layer, reduces the porosity of the winding layer, and ensures the density and stability of the casing structure.

Description

Technical Field

[0001] This invention relates to the field of missile engine combustion chamber technology, and more specifically, to a multi-stage pressure- and temperature-controlled molding method for ablation-resistant missile engine casing. Background Technology

[0002] The missile engine casing is a core load-bearing and protective component of the missile propulsion system, widely used in various weapons and equipment such as tactical and strategic missiles. Its operating environment is extremely harsh: it must withstand the scouring of thousands of degrees Celsius generated by the exhaust gases after engine ignition, as well as the severe impact of high-pressure exhaust gases, vibration loads, and chemical corrosion. Simultaneously, it must meet the missile's lightweight and high-precision design requirements to ensure the missile's range, maneuverability, and long-term storage reliability. Therefore, the casing's ablation resistance, thermal insulation performance, structural strength, dimensional accuracy, and interlayer bonding stability directly determine the missile engine's operating efficiency and service safety, placing extremely high standards on the scientific rigor and precision of its manufacturing process.

[0003] Currently, the industry primarily employs a composite molding process of "metal liner + composite material winding" for manufacturing ablation-resistant missile engine casings. A typical process involves: after simple grinding and cleaning of the metal substrate, directly laying and winding a resin-based composite material, then vacuum-sealing the entire casing before placing it in an autoclave for one-time curing. After curing, the outer surface is machined using conventional turning methods. Some processes add reinforcing phases such as high-silica glass fiber or carbon fiber to the composite material, or modify the resin to improve the casing's ablation resistance. Regarding compaction, most processes use a pre-vacuum extraction method after winding, lacking process-specific compaction control.

[0004] However, the existing processes described above have certain problems in actual production and application: On the one hand, the material pretreatment process lacks systematic control, and the cleanliness of the metal surface and the storage and thawing conditions of the composite material are not strictly controlled, resulting in insufficient bonding between the metal liner and the composite material layers. Under high temperature and high pressure, delamination and peeling are prone to occur. At the same time, the resin content and fiber distribution uniformity of the composite material itself are difficult to guarantee, resulting in large fluctuations in the shell's ablation resistance and structural strength, which cannot stably meet the requirements of harsh working conditions. On the other hand, the process coordination in the molding process is insufficient. There is a lack of targeted intermediate compaction treatment during the winding process, resulting in high interlayer porosity. The temperature and pressure curves in the curing stage do not match the material properties well, which easily leads to internal stress concentration. The selection of cutting parameters in the subsequent machining stage is coarse, which not only affects the dimensional accuracy of the shell but may also cause surface damage, further increasing the risk of shell failure during service. Ultimately, this leads to a shortened service life and reduced reliability of the shell, making it difficult to meet the high-performance requirements of modern missile propulsion systems. Therefore, we urgently need a multi-stage pressure- and temperature-controlled molding method for ablation-resistant missile engine shells to solve the above problems. Summary of the Invention

[0005] One objective of this invention is to provide a new technical solution for a multi-stage pressure- and temperature-controlled molding method for ablation-resistant missile engine casings. Through tooling pretreatment, lining treatment, layered winding and compaction, and precise curing molding, the method achieves tight interlayer bonding, meets dimensional accuracy standards, increases interlayer shear strength to over 50 MPa, reduces porosity to below 1%, improves high-temperature erosion resistance, and meets the stringent operating conditions of missile engines.

[0006] The objective of this invention is achieved as follows: a multi-stage pressure- and temperature-controlled molding method for ablation-resistant missile engine casing, comprising the following steps:

[0007] S1: Tooling and mandrel pretreatment: Clean and inspect the mandrel for defects in the mold, and treat the mandrel with a release agent;

[0008] S2: Metal lining surface treatment: Grinding and cleaning the outer surface of the metal lining;

[0009] S3: Applying epoxy film: Applying epoxy film to the outer surface of the treated metal lining;

[0010] S4: Composite material winding: On the outer surface of the epoxy film, barium phenolic resin high silica glass fiber prepreg is mechanically overlapped and wound along a preset direction to form a composite material winding layer; during the winding process, after each preset number of winding layers, the wound composite material layer is subjected to an intermediate compaction treatment;

[0011] S5: Vacuum sealing: Vacuum bag sealing of the wound workpiece;

[0012] S6: Curing and molding: Place the vacuum-sealed workpiece in an autoclave and cure it according to the preset pressure and temperature program;

[0013] S7: Machining: The outer surface of the cured workpiece is machined to achieve the predetermined dimensions.

[0014] Optionally, in S1, cleaning and defect inspection includes: drying the mold for the first time in production in an oven at 180±5℃ for 3 hours to remove oil; cleaning the mold surface with ethyl acetate using medical degreasing gauze at least 3 times; if there are defects such as bumps, scratches or Teflon coating peeling off on the mold surface, they need to be repaired; if it cannot be laid immediately, the surface is covered with a non-porous release film.

[0015] Optionally, in S1, the release agent treatment is as follows: a silicone-based release agent with a solid content of 10%-15% is used to wet lint-free wiping paper and is applied in a spiral pattern along the surface of the laying mandrel at least 3 times, with an interval of 15 minutes between each application; after the last application, the paper is dried at room temperature for 30 minutes.

[0016] Optionally, in S2, the metal liner is a tungsten-based alloy with a composition of 93WNiFe; the surface treatment is as follows: polishing with 80-grit sandpaper until there are no reflective spots on the outer surface, and then cleaning with acetone until there are no impurities left after wiping with white wiping paper.

[0017] Optionally, in S3, the epoxy film thickness is 0.1-0.3 mm, and the glass transition temperature is not lower than 120°C.

[0018] Optionally, in S4, the preset direction is from the rear end of the mold to the front end; the preset number of layers is 3-8 layers; the overlap rate of the mechanical overlapping winding is 30%-50%, and the linear speed is 0.5-1.5m / min.

[0019] Optionally, in S4, the intermediate compaction process is a vacuum bag pre-extraction molding, specifically: a vacuum bag is laid on the outer surface of the 5-layer prepreg that has been wound, vacuumed to -0.09MPa and held for 5 minutes before the pressure is released; after the winding is completed, the thickness of the composite material winding layer is not less than 5mm.

[0020] Optionally, in S4, the resin content of the barium phenolic resin high-silica glass fiber prepreg is 35%-45%, and the diameter of the high-silica glass fiber monofilament is 5-10 μm.

[0021] Optionally, in S5, the vacuum sealing includes: sequentially laying a peelable fabric, a non-porous release film, a breathable felt, and a bag-making film on the surface of the composite material winding layer; setting vacuum nozzles at both ends of the mold; after sealing, evacuating to -0.095MPa, and maintaining pressure for 10 minutes with a pressure drop not exceeding 0.01MPa.

[0022] Optionally, in S6, the curing process includes: first, increasing the pressure to 1 MPa at 0.02 MPa / min and holding the pressure for 10 min, while maintaining a vacuum degree not lower than -0.075 MPa; then, increasing the temperature and pressure according to a preset program, sequentially passing through stages of 70℃ / 1.0 MPa, 80℃ / 1.5 MPa, 90℃ / 2.0 MPa, and 135℃ / holding for 90 min, and finally holding at 160℃ / 3.0 MPa for 120 min; after the curing process is completed, controlling the temperature to drop below 80℃ at a rate of 0.2-0.5℃ / min, and then naturally cooling to room temperature and depressurizing.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. According to one embodiment of this disclosure, the ablation-resistant missile engine casing manufacturing process effectively improves the interlayer bonding strength between the metal liner and the composite material winding layer, reduces the porosity of the winding layer, and ensures the compactness and stability of the casing structure by refining the pretreatment of tooling and mandrel, polishing and cleaning the metal liner, and accurately laying the epoxy film, combined with the multi-layer intermediate compaction process during the composite material winding process.

[0025] 2. According to one embodiment of this disclosure, the ablation-resistant missile engine casing manufacturing process adopts a staged heating and pressurization curing procedure, adapting to the curing reaction characteristics of barium phenolic resin high silica glass fiber prepreg, and combining strict vacuum sealing pressure control and precise machining process, thereby achieving a dual improvement in casing dimensional accuracy and ablation resistance, enabling the finished casing to meet the stringent operating conditions of high temperature, high pressure and gas erosion of missile engines. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the assembly structure of the metal liner and composite material winding layer of the present invention.

[0028] Figure 2 This is a schematic diagram of the layered unfolded structure of the composite material winding layer and the metal liner of the present invention.

[0029] Figure 3 This is a schematic diagram of the mounting mandrel and mandrel support section of the present invention.

[0030] Figure 4 This is a flowchart of the present invention.

[0031] The diagram shows the following: 1. Metal liner; 2. Composite material winding layer; 3. Mandrel; 4. Positioning hole; 5. Mandrel support section. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] like Figure 1-4 As shown, a multi-stage pressure- and temperature-controlled molding method for an ablation-resistant missile engine casing includes the following steps:

[0034] S1: Tooling and mandrel pretreatment: Clean and inspect the mandrel 3 for defects in the mold, and treat the mandrel 3 with a release agent.

[0035] In S1, cleaning and defect inspection include: receiving the mold and recording the mold number and product serial number; drying the mold for the first time in production in an oven at 180±5℃ for 3 hours to remove oil; cleaning the mold surface with ethyl acetate using medical degreased gauze at least 3 times; if there are defects such as bumps, scratches or Teflon coating peeling on the mold surface, they need to be repaired; if it cannot be laid immediately, cover the surface with a non-porous release film.

[0036] Here, the mold number and product serial number are recorded to achieve traceability of the production process, which is convenient for subsequent process optimization or problem tracing. The first mold is dried in an oven at 180±5℃ for 3 hours to remove oil, which can completely remove the processing oil stains on the mold surface, prevent the oil stains from transferring to the prepreg surface, and ensure the interlayer bonding of the composite material. Medical degreased gauze soaked in ethyl acetate is used for cleaning, which can avoid the lint residue of ordinary gauze and prevent impurities on the bonding surface from affecting the shell molding quality.

[0037] Furthermore, after the defects in the molded surface are repaired, a surface roughness tester must be used again to ensure that the roughness of the repaired area is consistent with the original surface (Ra≤0.8μm), which can avoid uneven prepreg laying caused by local roughness differences.

[0038] Furthermore, when covering with a non-porous release liner, the edges must be sealed with tape to completely isolate external dust and moisture, keeping the surface clean until the installation begins.

[0039] In S1, the release agent treatment is as follows: use a silicone-based release agent with a solid content of 10%-15%, wet the lint-free wiping paper, and apply it in a spiral and orderly manner along the surface of the laying mandrel 3 at least 3 times, with an interval of 15 minutes between each application; after the last application, dry at room temperature for 30 minutes.

[0040] Here, a silicone-based release agent with a solid content of 10%-15% is selected. Its release effect is stable and it will not react chemically with the prepreg resin, thus avoiding affecting the performance of the shell. Wetting a lint-free wiping paper that is free of impurities and lint and applying it in a spiral and orderly manner can ensure that the release agent film layer is uniform and continuous, without any missed coating or accumulation.

[0041] Furthermore, wiping each layer of the release agent 15 minutes apart allows the previous layer to cure initially, preventing the film from becoming too thick and peeling off due to multiple layers of application.

[0042] Furthermore, after drying at room temperature, the gloss uniformity of the mandrel surface is tested using a gloss meter, which verifies the integrity of the release agent film and prevents local release failure from causing the shell and mandrel to stick together.

[0043] S2: Surface treatment of metal liner 1: Grinding and cleaning the outer surface of metal liner 1.

[0044] In S2, the metal liner 1 is a tungsten-based alloy with a composition of 93WNiFe; the surface treatment is as follows: polishing with 80-grit sandpaper until there are no reflective spots on the outer surface, and then cleaning with acetone until there are no impurities left after wiping with white wiping paper.

[0045] Here, GWF93, a tungsten-based alloy with a composition of 93WNiFe, is selected as the metal liner 1. It has excellent high temperature resistance and ablation resistance, which can improve the basic load-bearing capacity and erosion resistance of the shell. The outer surface is polished with 80-grit sandpaper until there are no reflective spots. This can remove the oxide layer on the metal surface without causing excessive scratches, and can ensure that the surface roughness is suitable for the adhesive film application.

[0046] Furthermore, after cleaning with acetone until no impurities remain after wiping with white wiping paper, it is found that the acetone has high volatility and excellent cleaning power, which can thoroughly remove metal shavings and oil stains generated during polishing, and prevent residual impurities from affecting the bonding strength of the adhesive film.

[0047] Furthermore, after cleaning, the metal liner 1 must be covered with adhesive film within 2 hours to prevent secondary oxidation of the surface of the metal liner 1 and maintain surface cleanliness and activity.

[0048] S3: Apply epoxy film: Apply epoxy film to the outer surface of the treated metal lining 1.

[0049] In S3, the epoxy film thickness is 0.1-0.3 mm, and the glass transition temperature is not lower than 120℃.

[0050] Here, an epoxy film with a thickness of 0.1-0.3 mm is selected to ensure the adhesion between the metal liner 1 and the composite material layer, while avoiding stress concentration caused by excessive film thickness; the glass transition temperature is not lower than 120℃ to adapt to the temperature environment of the subsequent curing process and prevent the film from failing during the curing process.

[0051] S4: Composite material winding: On the outer surface of the epoxy film, barium phenolic resin high silica glass fiber prepreg is mechanically overlapped and wound along a preset direction to form composite material winding layer 2; During the winding process, after each preset number of winding layers is accumulated, the wound composite material layer is subjected to an intermediate compaction treatment.

[0052] In S4, the preset direction is from the rear end of the mold to the front end; the preset number of layers is 3-8 layers; the overlap rate of mechanical overlapping winding is 30%-50%, and the linear speed is 0.5-1.5m / min.

[0053] Here, the preset direction is selected from the rear end of the mold to the front end, which can be adapted to the support structure of the mold and avoid interference between the prepreg and the mold during the winding process; the preset number of layers is 3-8 layers, which can balance the winding efficiency and the interlayer compaction effect, and avoid the problem of air not being able to escape between layers due to too many layers; the overlap rate of mechanical overlapping winding is controlled at 30%-50%, which can ensure the continuity and density of the winding layers and avoid gaps; the linear speed is set to 0.5-1.5m / min, which can be adapted to the resin flow of the prepreg and prevent the prepreg from being stretched and deformed due to excessive linear speed, or the resin from accumulating due to excessive linear speed.

[0054] Furthermore, the winding length of the cylinder is measured with a tape measure during winding, which allows for real-time monitoring of the winding range and avoids exceeding the mold application area.

[0055] Furthermore, after the winding is completed, the cylinder diameter is measured every 50mm from the die marking position to ensure the uniformity of the winding layer thickness, with a deviation of no more than 0.2mm.

[0056] In S4, the intermediate compaction process is a vacuum bag pre-extraction molding, specifically: a vacuum bag is laid on the outer surface of the 5-layer prepreg that has been wound, vacuumed to -0.09MPa and held for 5 minutes before the pressure is released; after the winding is completed, the thickness of the composite material winding layer 2 is not less than 5mm.

[0057] Here, after every 5 layers of winding, a vacuum bag is pre-extracted and formed to promptly remove interlayer air and reduce the porosity of the winding layer; vacuuming to -0.09MPa and maintaining it for 5 minutes can maximize the removal of interlayer air without damaging the prepreg; after winding, the thickness of the composite material winding layer 2 is not less than 5mm, which can ensure the shell's ablation resistance and heat insulation performance and meet the working conditions.

[0058] Furthermore, the sealing width of the vacuum bag edge is not less than 10cm to prevent air leakage during vacuuming and ensure the compaction effect.

[0059] Furthermore, checking the surface flatness of the prepreg after depressurization can promptly identify interlayer defects, preventing irreparable damage after subsequent curing.

[0060] In S4, the resin content of the barium phenolic resin high-silica glass fiber prepreg is 35%–45%, and the diameter of the high-silica glass fiber monofilament is 5–10 μm.

[0061] Here, the resin content of the prepreg is controlled at 35%-45%, which can balance the viscosity of the prepreg and the density after molding, ensuring the quality of winding and curing; the diameter of the high silica glass fiber monofilament is 5-10μm, which can improve the fiber's ablation resistance and the density of the winding layer; the prepreg is stored in a cold storage at -18℃ to -10℃ and the shelf life does not exceed 6 months, which can delay resin aging and ensure the stability of the prepreg performance.

[0062] Furthermore, after being removed from the cold storage, the prepreg should be kept sealed until it reaches room temperature, and the thawing time should be no less than 6 hours. This can prevent the prepreg resin from absorbing moisture and avoid air bubble defects after curing. The sealed bag can only be opened when there is no moisture on its surface. Prepreg rolls or bags containing moisture should be discarded to avoid the negative impact of defective materials on the overall performance of the shell.

[0063] Furthermore, when removing the material from the clean room after opening the bag, sealing it in a moisture-proof bag can prevent the prepreg from being contaminated with impurities or absorbing moisture during transportation.

[0064] S5: Vacuum sealing: Vacuum bag sealing of the wound workpiece.

[0065] In S5, vacuum sealing includes: sequentially laying a peelable fabric, a non-porous release film, a breathable felt, and a bag-making film on the surface of the composite material winding layer 2; setting vacuum nozzles at both ends of the mold; after sealing, evacuating to -0.095MPa, and maintaining pressure for 10 minutes with a pressure drop not exceeding 0.01MPa.

[0066] Here, the residual putty strips on the tooling are cleaned and sanded with 400# sandpaper until no residual adhesive substances remain, which can prevent residual adhesive substances from affecting the vacuum sealing effect; on the surface of the composite material winding layer 2, a peelable fabric, a non-porous release film, a breathable felt, and a bag-making film are laid in sequence: the effective spreading area of ​​the peelable fabric is not less than the effective spreading area of ​​the first layer of prepreg, and the effective spreading area of ​​the non-porous release film is not less than the effective spreading area of ​​the peelable fabric; the peelable fabric facilitates subsequent demolding, the non-porous release film prevents resin from sticking to the breathable felt, the breathable felt ensures the gas exhaust channel, and the bag-making film achieves overall sealing, which can form a stable vacuum sealing structure.

[0067] Furthermore, the thickness of the breathable felt is 5-8mm and the air permeability is not less than 5×10⁻³cm³ / (cm²・s・Pa), which can ensure that the gas can be discharged smoothly while avoiding the space occupied by the excessively thick breathable felt; the vacuum nozzle is placed with suspended pleats and does not contact the surface of the composite part, which can prevent the vacuum nozzle from being compacted and causing poor air exhaust; at least 3 layers of breathable felt are placed between the vacuum nozzle base and the workpiece, which can prevent the vacuum nozzle base from damaging the surface of the composite part.

[0068] Furthermore, after encapsulation, the vacuum is evacuated to -0.095MPa and the pressure drop does not exceed 0.01MPa within 10 minutes, which verifies the sealing performance of the vacuum system and prevents air ingress during the curing process from causing defects. Using soapy water to detect the seal can accurately locate the leakage point and ensure the reliability of the encapsulation.

[0069] S6: Curing and molding: Place the vacuum-sealed workpiece in an autoclave and cure it according to the preset pressure and temperature program.

[0070] In S6, the curing process includes: first, pressurizing to 1 MPa at 0.02 MPa / min and holding for 10 min, while maintaining a vacuum of no less than -0.075 MPa; then, increasing the temperature and pressure according to the preset program, successively passing through stages of 70℃ / 1.0 MPa, 80℃ / 1.5 MPa, 90℃ / 2.0 MPa, and 135℃ / holding for 90 min, and finally holding at 160℃ / 3.0 MPa for 120 min; after the curing process is completed, the temperature is controlled to drop below 80℃ at a rate of 0.2-0.5℃ / min, and then naturally cooled to room temperature and depressurized.

[0071] Here, a thermocouple is installed on the surface of the vacuum bag and connected to the vacuum system to monitor the actual temperature of the workpiece in real time, avoiding uneven curing of the workpiece due to temperature difference in the autoclave cavity; increasing the pressure from 0.02MPa / min to 1MPa can avoid sudden pressure increase that could cause the vacuum bag to break; maintaining the vacuum degree at no less than -0.075MPa during the 10-minute pressure holding period can continuously remove the volatiles generated during the curing process.

[0072] Furthermore, the phased heating and pressurization according to the preset program can be adapted to the resin curing reaction process and avoid internal stress concentration; after depressurization and rearranging the vacuum bag if the vacuum degree requirement is not met, defects such as pores and delamination can be avoided during the curing process.

[0073] Furthermore, after the curing process is completed, the temperature is controlled to drop below 80°C at a rate of 0.2-0.5°C / min to prevent the workpiece from deforming or cracking due to sudden temperature changes; after natural cooling to room temperature, the pressure is released to further release internal stress and ensure the dimensional stability of the shell.

[0074] Table 1: Temperature-Pressure Process Curing Curing Steps

[0075]

[0076] S7: Machining: The outer surface of the cured workpiece is machined to achieve the predetermined dimensions.

[0077] In S7, the machining operations include: using a gantry crane to lift the mold, clamping it using a "one clamp, one support" method, fixing one end of the mold with a four-jaw chuck and installing a limit support, and fixing the other end with a lathe center; operating slowly during clamping, using a dial indicator to measure the outer diameter runout value, adjusting the jaws to ensure that the radial runout value is no greater than 0.2mm and the high points are aligned; using turning to perform two cuts, the first roughing cut has a cutting speed of 50-80m / min and a feed rate of 0.8mm, and the second finishing cut has a cutting speed of 100-150m / min and a feed rate of 0.4mm; turning the lathe dust collector fan is turned on during machining.

[0078] Here, the "one clamp and one top" clamping method is used to reduce mold clamping deformation and ensure the stability of the machining datum. During the clamping process, the jaws are adjusted so that the radial runout value is no more than 0.2mm and the high point direction is consistent, which can ensure the roundness accuracy of the shell after machining.

[0079] Furthermore, the turning process involves two cutting operations: the first roughing operation quickly removes excess material, while the second finishing operation ensures dimensional accuracy and surface quality. The roughing cutting speed is 50-80 m / min with a feed rate of 0.8 mm, and the finishing cutting speed is 100-150 m / min with a feed rate of 0.4 mm. This method is suitable for composite structures made of tungsten-based alloys and composite materials, preventing chipping or overheating during machining.

[0080] Furthermore, turning on the lathe's dust removal fan during machining can promptly remove cutting dust and prevent dust from adhering and affecting surface quality.

[0081] Example 1: The metal liner 1, serving as the basic load-bearing structure of the shell, has its outer surface tightly fitted onto the outer circumferential surface of the laying mandrel 3 after grinding and cleaning in step S2. The radial dimension of the mandrel is precisely matched with the inner hole dimension of the metal liner 1 (gap ≤ 0.02mm), providing rigid support for the molding of the metal liner 1. Throughout the process, the positioning bosses at both ends of the laying mandrel 3 need to be embedded in the positioning holes 4 at the corresponding positions in the mold to achieve precise positioning and circumferential fixation of the laying mandrel 3 in the mold. The positioning holes 4 are opened at preset positions on the end face and side wall of the mold. By cooperating with the positioning bosses / positioning pins at the ends of the laying mandrel 3, they restrict the axial and circumferential movement of the mandrel during the winding and curing process. Rotation ensures the axial and circumferential winding accuracy of the shell. The mandrel support section 5 is distributed in the middle and near both ends of the mandrel 3. It needs to contact the support groove / wear-resistant pad on the inner wall of the mold to disperse the radial tension load on the mandrel during winding, avoid bending deformation of the mandrel, and thus ensure the uniformity of the shell wall thickness and dimensional accuracy. The composite material winding layer 2 is uniformly attached to the outer surface of the metal liner 1 through the mechanical overlapping winding process in step S4, using the epoxy film laid in step S3 as the bonding transition layer. It forms an integrated composite structure of "liner-film-winding layer" with the metal liner 1, which together bears the high temperature, high pressure and gas scouring load during the operation of the missile engine.

[0082] In this invention, firstly, step S1 involves cleaning and inspecting the mandrel 3 and mold for defects, and applying a release agent to establish a stable molding benchmark. The positioning hole 4 and the mandrel positioning boss work together to limit mandrel movement, and the mandrel support section 5 disperses radial load, ensuring the dimensional accuracy benchmark for subsequent molding. Subsequently, step S2 involves grinding and cleaning the tungsten-based alloy metal liner 1, and step S3 involves applying the epoxy film. This improves the surface activity and adhesion of the metal, and the film forms a transitional bonding layer between the liner and the composite material, laying the foundation for an integrated structure. Step S4 uses barium phenolic resin high-silica glass fiber prepreg for directional mechanical winding, combined with intermediate compaction every five layers, ensuring the winding... While ensuring the density of the winding layer, the synergistic effect of the prepreg resin and fiber enhances the shell's ablation resistance. The winding layer and the metal liner 1 form a "load-bearing-protection" composite structure. The vacuum sealing in step S5 and the staged heating and pressurizing curing in step S6 use a continuous vacuum environment to remove volatiles and pores, adapt to the resin curing reaction process to release internal stress, and ensure stable interlayer bonding. Finally, the precise machining in step S7 ensures the dimensional accuracy of the shell. Through the synergistic effect of the basic load-bearing of the metal liner 1, the ablation protection of the composite winding layer 2, and the reference support of the mandrel 3 and the mold, the finished shell meets the stringent operating conditions of high temperature, high pressure, and exhaust gas erosion of the missile engine.

[0083] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A multi-stage pressure- and temperature-controlled molding method for an ablation-resistant missile engine casing, characterized in that: Includes the following steps: S1: Tooling and mandrel pretreatment: Clean and inspect the mandrel for defects in the mold, and treat the mandrel with a release agent; S2: Metal lining surface treatment: Grinding and cleaning the outer surface of the metal lining; S3: Applying epoxy film: Applying epoxy film to the outer surface of the treated metal lining; S4: Composite material winding: On the outer surface of the epoxy film, barium phenolic resin high silica glass fiber prepreg is mechanically overlapped and wound along a preset direction to form a composite material winding layer with a thickness of not less than 5mm; During the winding process, after every 3-8 layers are wound, the wound composite material layer is subjected to an intermediate compaction treatment, which reduces the interlayer porosity of the composite material winding layer to below 1%. S5: Vacuum sealing: Vacuum bag sealing of the wound workpiece; S6: Curing and molding: The vacuum-sealed workpiece is placed in an autoclave and cured according to a staged heating and pressurization program, wherein the staged heating and pressurization program increases the interlaminar shear strength of the composite material winding layer to more than 50MPa. S7: Machining: The outer surface of the cured workpiece is machined to achieve the predetermined dimensions.

2. The multi-stage pressure-controlled and temperature-controlled molding method for an ablation-resistant missile engine casing according to claim 1, characterized in that: In S1, cleaning and defect inspection include: the molds used for the first production run are dried in an oven at 180±5℃ for 3 hours to remove oil; the mold surface is cleaned with ethyl acetate using medical degreased gauze at least 3 times; if there are defects such as bumps, scratches or Teflon coating peeling off on the mold surface, they need to be repaired; if the mold cannot be laid immediately, the surface is covered with a non-porous release film.

3. The multi-stage pressure-controlled and temperature-controlled molding method for an ablation-resistant missile engine casing according to claim 1, characterized in that: In S1, the release agent treatment is as follows: use a silicone-based release agent with a solid content of 10%-15%, wet the lint-free wiping paper, and apply it in a spiral pattern along the surface of the laying mandrel at least 3 times, with an interval of 15 minutes between each application; after the last application, dry at room temperature for 30 minutes.

4. The multi-stage pressure-controlled and temperature-controlled molding method for an ablation-resistant missile engine casing according to claim 1, characterized in that: In S2, the metal liner is a tungsten-based alloy with a composition of 93WNiFe or other high-density high-temperature resistant alloys; the surface treatment is as follows: polishing with 80-grit sandpaper until there are no reflective spots on the outer surface, and then cleaning with acetone until there are no impurities left after wiping with white wiping paper.

5. The multi-stage pressure-controlled and temperature-controlled molding method for an ablation-resistant missile engine casing according to claim 1, characterized in that: In S3, the epoxy film thickness is 0.1mm-0.3mm, and the glass transition temperature is not lower than 120℃.

6. The multi-stage pressure-controlled and temperature-controlled molding method for an ablation-resistant missile engine casing according to claim 1, characterized in that: In S4, the preset direction is from the rear end of the mold to the front end; the preset number of layers is 3-8 layers; the overlap rate of the mechanical overlapping winding is 30%-50%, and the linear speed is 0.5m / min-1.5m / min.

7. The multi-stage pressure-controlled and temperature-controlled molding method for an ablation-resistant missile engine casing according to claim 1, characterized in that: In S4, the intermediate compaction process is a vacuum bag pre-extraction molding, specifically: a vacuum bag is laid on the outer surface of the 5-layer prepreg that has been wound, vacuumed to -0.08MPa to -0.095MPa and held for 3min to 8min before releasing the pressure; after the winding is completed, the thickness of the composite material winding layer is not less than 5mm.

8. The multi-stage pressure-controlled and temperature-controlled molding method for an ablation-resistant missile engine casing according to claim 1, characterized in that: In S4, the resin content of the barium phenolic resin high silica glass fiber prepreg is 35%-45%, and the diameter of the high silica glass fiber monofilament is 5μm-10μm.

9. The multi-stage pressure-controlled and temperature-controlled molding method for an ablation-resistant missile engine casing according to claim 1, characterized in that: In S5, the vacuum sealing includes: sequentially laying a peelable fabric, a non-porous isolation film, a breathable felt, and a bag-making film on the surface of the composite material winding layer; setting vacuum nozzles at both ends of the mold; after sealing, evacuating to -0.095MPa, and maintaining the pressure for 10 minutes with a pressure drop not exceeding 0.01MPa.

10. The multi-stage pressure-controlled and temperature-controlled molding method for an ablation-resistant missile engine casing according to claim 1, characterized in that: In S6, the curing process includes: first, increasing the pressure to 1 MPa at 0.02 MPa / min and holding the pressure for 10 min, while maintaining a vacuum degree not lower than -0.075 MPa; then increasing the temperature and pressure according to a preset program, sequentially passing through stages of 70℃ / 1.0 MPa, 80℃ / 1.5 MPa, 90℃ / 2.0 MPa, and 135℃ / holding for 90 min, and finally holding at 160℃ / 3.0 MPa for 120 min; or adopting a staged temperature and pressure curing process equivalent to the above curing process; after the curing process is completed, controlling the temperature to drop below 80℃ at a rate of 0.2-0.5℃ / min, then naturally cooling to room temperature and depressurizing.

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