Rocket engine nozzle reverse and forward bidirectional pressure-bearing plugging cover and its forming and bonding method

Abstract

The invention relates to the technical field of plugging cover structure design of ejection rocket engines, and discloses a reverse and forward bidirectional pressure-bearing plugging cover for a rocket engine nozzle and a forming and bonding method thereof. The plugging cover comprises a sealing portion, a bonding portion, and a variable wall thickness stiffness smooth transition structure is arranged at the connection between the plugging cover and the bonding cover to form an integrated spherical curved surface structure with variable wall thickness, equal strength on the front side, and equal stiffness on the side side. The plugging cover is made of a composite material of filament bundle fibers, short filament bundle fibers and modified phenolic resin, and has the advantages of directional critical pressure blasting, high strength, low density, and small volume. The plugging cover is designed to have a variable wall thickness stiffness smooth transition structure and a stacking orientation requirement of filament bundle fibers and short filament bundle fibers in a microscopic direction (arranged in a direction parallel to the inner wall surface of a mold cavity) to achieve the function of bearing high reverse pressure and low forward pressure, and can meet high pressure, high temperature, and high speed fuel gas impact ejection within 20MPa, and meets the preparation requirements of ejection rocket engines.

Description

Technical Field

[0001] The invention relates to the technical field of plugging cover structure design for ejection-type rocket engines, and in particular to a reverse and forward bidirectional pressure-bearing plugging cover for a rocket engine nozzle and a molding and bonding method thereof. Background Art

[0002] At present, the materials of rocket engine nozzle plugging caps are mainly metal, rubber, foam and other materials. The opening structure of the metal plugging cap is a shear groove structure. When it is opened under pressure, it is destroyed from the root of the shear groove and then flies out as a whole. It has the advantages of stable opening pressure and high precision. It is used in a large number of engines, but has defects such as low reverse pressure, no pressure difference between positive and reverse pressure, and flying objects damaging the launching mechanism. The rubber plugging cap and the foam plugging cap are disc-shaped structures. When the plugging cap is opened, the pre-destruction layer is torn. It has the advantages of no flying objects and stable opening pressure, but has problems such as low opening pressure, aging with storage time, and poor adaptability to temperature environment. They cannot meet the ejection environment of high pressure, high pressure in the reverse direction, and low pressure in the forward direction.

[0003] With the development of long-flight and shipborne weapons and equipment, requirements for rocket engine nozzle plugs are being raised such as no flying objects or large flying objects, withstanding reverse high pressure / forward low pressure, and high technical maturity. However, existing metal plugs have large flying objects, and rubber and foam plugs have defects such as low pressure bearing, aging, and poor adaptability to temperature and environment, which cannot meet the preparation requirements of ejection rocket engines.

[0004] In view of this, the present invention provides a new plugging cover with low density, high reverse impact resistance and low opening pressure, and a molding and bonding method thereof. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a rocket engine nozzle reverse and forward bidirectional pressure-bearing plug cover and a molding and bonding method thereof to solve the technical problems mentioned in the prior art.

[0006] A reverse and forward bidirectional pressure-bearing plugging cover for a rocket engine nozzle, the plugging cover being installed inside a nozzle expansion section, wherein the plugging cover comprises a plugging portion and a bonding portion, the plugging portion being a spherical cap structure, the bonding portion being arranged near the edge of a convex spherical surface of the plugging portion, the spherical cap structure of the plugging portion extending from the center to the surroundings to be provided with a plurality of sections of load-bearing areas, and the front and back surfaces of the plurality of sections of the load-bearing areas are both arranged as high-order equation surfaces of equivalent design profiles;

[0007] The connection between the plugging portion and the bonding portion is set as a rigidity matching zone, and the rigidity matching zone is a rigidity smooth transition structure with variable wall thickness, and the rigidity smooth transition structure with variable wall thickness extends from its central part toward the plugging portion and the bonding portion in sequence, and the inner and outer sides of the rigidity smooth transition structure with variable wall thickness are smoothly connected with the inner and outer surfaces of the plugging portion and the bonding portion respectively, so as to form the plugging cover of the integrated variable wall thickness ellipsoid structure, and the surface of the plugging cover has no shear groove;

[0008] The material of the plugging cover is a composite laminated injection phenolic resin material of FB-1 modified filament bundles and short filament bundles, and the pressure-bearing function of the front and back sides is obtained by the orientation of the filament bundles.

[0009] Optionally, the FB-1 modified filament bundle and short filament bundle fiber composite laminated injection phenolic resin material is composited and generated by filament bundle fibers, short filament bundle fibers and modified phenolic resin, wherein;

[0010] The long filament bundle fibers and the short filament bundle fibers are stacked in several layers according to a set rule to form a substrate; the set rule is: according to the design strength of the plugging cover, the long filament bundle fibers are stacked in sequence along the center to both sides with a preset unit amount of the short filament bundle fibers in accordance with the stacking orientation requirements in the microscopic direction by cross-weaving or overlapping connection;

[0011] The modified phenolic resin is filled in the gaps and / or the molding surface of the substrate.

[0012] Optionally, the weight ratio of the modified phenolic resin is set to:

[0013] 100 parts of phenolic resin, 10-15 parts of toughening filler, 2-5 parts of reinforcing filler, 2-5 parts of coupling agent, 0.5-1 part of zinc stearate.

[0014] Optionally, the thickness of the central portion of the variable wall thickness stiffness smooth transition structure is at least twice the thickness of the largest thickness between the blocking portion and the bonding portion.

[0015] Optionally, the length of the bonding surface of the bonding portion is set to 30-50 mm, and the thickness of the bonding surface of the bonding portion is set to 3-5 mm.

[0016] A method for forming a reverse and forward bidirectional pressure-bearing plugging cover for a rocket engine nozzle, the method being applied to preparing the plugging cover described above, the method comprising the following steps:

[0017] S1. According to the design structure of the plugging cover, weigh corresponding molding materials for use, wherein the molding materials include a preset unit amount of long filament fiber, short filament fiber and modified phenolic resin;

[0018] S2, stacking the long filament fiber and the short filament fiber in sequence into a mold cavity of a forming mold according to a set stacking orientation requirement to form a substrate, and locking the forming mold;

[0019] S3, injecting the modified phenolic resin into the mold cavity of the molding mold through the injection port, so that the modified phenolic resin is evenly filled into the gaps and / or molding surfaces of the substrate, and then heat-treating the molding mold, cooling it to room temperature and demoulding it to obtain the plugging cover.

[0020] Optionally, in S3, the heat treatment includes:

[0021] S3-01, heating the molding die to 70-90° C., and then keeping the temperature for 0.8-1.2 h;

[0022] S3-02, continue to heat the molding die to 150-180° C., and then keep the temperature for 1-3 hours;

[0023] S3-03, cooling the molding die to 40-60°C, and then keeping the temperature for 22-26 hours.

[0024] Optionally, the heating rate in S3-01 and S3-02 is 2 to 5°C / min.

[0025] A method for bonding a reverse and forward bidirectional pressure-bearing plugging cover of a rocket engine nozzle, the method being used to bond the plugging cover described above to the expansion section of the nozzle, the method comprising the following steps:

[0026] Grinding the bonding surface between the plugging cover and the inner surface of the nozzle;

[0027] Preparing a high temperature resistant adhesive, and then using the high temperature resistant adhesive to bond the plugging cover to the inner surface of the nozzle, and curing at room temperature for 6 to 8 hours;

[0028] The effective temperature range of the high temperature resistant adhesive is set to: -40 to 150°C.

[0029] Optionally, the weight ratio of the high temperature resistant adhesive is set as:

[0030] 100 parts of epoxy resin, 5-10 parts of curing agent, 10-20 parts of polysulfide rubber powder, 15-30 parts of mica.

[0031] The beneficial effects that the present invention can produce include:

[0032] The rocket engine nozzle reverse and forward bidirectional pressure-bearing plugging cover and its forming and bonding method provided by the present invention, the plugging cover comprises a plugging part, a bonding part and a variable wall thickness stiffness smooth transition structure arranged at the connection part, so as to form an integrated spherical curved surface structure with variable wall thickness, equal strength on the front side and equal stiffness on the side side; the plugging cover is made of a composite material of long filament bundle fibers, short filament bundle fibers and modified phenolic resin, and has the advantages of directional critical pressure blasting, high strength, low density and small volume; and the stiffness matching area of ​​the plugging cover is designed to be a variable wall thickness stiffness smooth transition structure and the long filament bundle fibers, short filament bundle fibers The stacking orientation requirement along the microscopic direction (set along the direction parallel to the inner wall of the mold cavity) realizes the function of bearing high reverse pressure and low forward pressure, so that there is no need to rely on shear grooves for blasting during operation, and can meet high-pressure, high-temperature, and high-speed gas impact ejection within 20MPa; and the forward opening pressure is designable (1MPa-8MPa), the weight of a single piece of opened fragments is small, and the product quality is stable. For example, the forward opening pressure of the plugging cover is consistent with the reverse pressure (the pressure-bearing performance of different batches of products is stable and almost without deviation) and has high reliability, which meets the preparation requirements of ejection-type rocket engines. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of the plugging cover of the present invention;

[0034] Figure 2 For the present invention Figure 1 A schematic diagram of a structure in which a plugging cover is bonded to an expansion section of a nozzle;

[0035] Figure 3 For the present invention Figure 1 Schematic diagram of the structural design of the load-bearing area, stiffness matching area and bonding surface of the plug cover;

[0036] Figure 4 For the present invention Figure 1 A schematic diagram of a process for forming a plugging cover;

[0037] Figure 5 For the present invention Figure 1 A schematic diagram of a process for bonding a plugging cover;

[0038] In the figure: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 are respectively the load-bearing areas of each section of the plugging cover, 12 is the stiffness matching area of ​​the plugging cover, 13 is the bonding strength assurance area of ​​the plugging cover, 14, plugging cover, 141, sealing part, 142, bonding part, 15, nozzle. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] See also Figure 1 As shown, the present invention provides a rocket engine nozzle reverse and forward bidirectional pressure-bearing plugging cover, such as Figure 2 As shown, the plugging cover 14 is installed inside the expansion section of the nozzle 15. The plugging cover 14 includes a plugging portion 141 and a bonding portion 142. The plugging portion 141 is a spherical cap structure, and the bonding portion 142 is arranged near the edge of the convex spherical surface of the plugging portion 141; Figure 3 As shown, the spherical cap structure of the plugging portion 141 is provided with 11 load-bearing areas extending from the center to the surroundings, and the front and back surfaces of the 11 load-bearing areas are set as high-order equation surfaces of equivalent design profiles. The load-bearing area obtains the front equal-strength surface and the side equal-rigidity surface of each area by interpolation method, and the load-bearing characteristics of the front side bearing low pressure and the side side bearing high pressure are realized by designing the curvature difference between the front and side surfaces; the connection between the plugging portion 141 and the bonding portion 142 is set as the stiffness matching area 12, and the stiffness matching area 12 is a stiffness smooth transition structure with variable wall thickness, and the stiffness smooth transition structure with variable wall thickness is arranged from its center toward It extends to the plugging portion 141 and the bonding portion 142, and the inner and outer sides of the variable wall thickness stiffness smooth transition structure are smoothly docked with the inner and outer surfaces of the plugging portion 141 and the bonding portion 142 respectively, so as to form an integrated variable wall thickness ellipsoidal structure plugging cover 14, and there is no shear groove on the surface of the plugging cover 14; the material of the plugging cover 14 is FB-1 modified long filament bundle and short filament bundle fiber composite stacked injection phenolic resin material, and the pressure difference function of the front and back sides is obtained by the orientation of the stacked filament bundles; the thickness of the central part of the variable wall thickness stiffness smooth transition structure is at least twice the thickness with the largest thickness value in the plugging portion 141 and the bonding portion 142. It is worth mentioning that the stiffness matching area 12 is the transition area between the bonding strength assurance area 13 of the plugging cover 14 and the 11th section load-bearing area. The design of the structural stiffness characteristics of this area is particularly important, such as Figure 3As shown, the connection part between the stiffness matching area 12 and the 11th load-bearing area of ​​the plugging cover 14 produces a small deformation when bearing load, while the connection part between the stiffness matching area 12 and the bonding strength assurance area 13 of the plugging cover 14 does not produce deformation when bearing load, so that the deformation of the plugging cover 14 is matched and transitioned from the small deformation of the 1st load-bearing area to the 11th load-bearing area to no deformation of the bonding strength assurance area 13 of the plugging cover 14, so as to ensure that the plugging cover 14 will not first be locally damaged at the connection part between the 11th load-bearing area and the stiffness matching area 12 when bearing positive pressure, and will not transfer the deformation of the 11th load-bearing area to the bonding strength assurance area 13 of the plugging cover 14 when bearing lateral pressure, resulting in the destruction of the bonding strength of the bonding strength assurance area 13 of the plugging cover 14, so that the plugging cover has the advantages of directional critical pressure blasting, high strength, low density, and small volume.

[0041] Furthermore, the FB-1 modified filament bundle and short filament bundle fiber composite laminated injection phenolic resin material is composited with filament bundle fibers, short filament bundle fibers and modified phenolic resin, wherein the filament bundle fibers and the short filament bundle fibers are laminated in several layers according to set rules to form a substrate; the set rules are that the filament bundle fibers are laminated and formed in turn along the center to both sides with a preset unit amount of short filament bundle fibers in accordance with the stacking orientation requirements in the microscopic direction by cross-weaving or overlap connection according to the design strength of the plugging cover 14; the modified phenolic resin is filled in the gaps and / or molding surface of the substrate. In the above, through the stacking structure of the long filament bundle fibers and the short filament bundle fibers in the plugging cover 14, it is possible to form a plurality of smaller fragments with blunted edges (not sharp) when the plugging cover 14 is opened in the forward direction; and the stacking orientation of the long filament bundle fibers and the short filament bundle fibers in the microscopic direction is required to be set along the direction parallel to the inner wall surface of the mold cavity of the molding mold to achieve the function of withstanding high reverse pressure and low forward pressure. Therefore, compared with the previous plugging cover structure, there is no need to rely on shear grooves for blasting during operation.

[0042] Furthermore, the weight ratio of the modified phenolic resin is set to 100 parts of phenolic resin, 10-15 parts of toughening filler, 2-5 parts of reinforcing filler, 2-5 parts of coupling agent, and 0.5-1 part of zinc stearate. In this embodiment, the toughening filler is preferably dibutyl ester, the reinforcing filler is preferably mica or aluminum oxide, and the coupling agent is preferably GX-550 (silane coupling agent).

[0043] Furthermore, the bonding surface length of the bonding portion 142 is set to 30-50 mm, and the bonding surface thickness of the bonding portion 142 is set to 3-5 mm. The bonding area of ​​the bonding portion 142 is controlled by design to ensure that the plugging cover 14 has sufficient bonding strength when subjected to positive and lateral pressure.

[0044] like Figure 4As shown, the present invention also provides a method for forming a reverse and forward bidirectional pressure-bearing plugging cover for a rocket engine nozzle, the forming method is applied to prepare the plugging cover 14 mentioned above, and the forming method comprises the following steps:

[0045] Step 1: According to the design structure of the plugging cover 14, weigh the corresponding molding material for use, the molding material including a preset unit amount of long filament fiber, short filament fiber and modified phenolic resin;

[0046] Step 2: stacking the long filament fiber and the short filament fiber in the mold cavity of the molding mold in sequence according to the set stacking orientation requirements to form a substrate, and locking the molding mold;

[0047] Step three, inject the modified phenolic resin into the mold cavity of the molding mold through the injection port, so that the modified phenolic resin is evenly filled into the gaps and / or molding surfaces of the substrate, and then the molding mold is heat-treated, cooled to room temperature for demoulding, and the plugging cover 14 is obtained. The heat treatment includes: heating the molding mold to 70-90°C, and then keeping it warm for 0.8-1.2h; continuing to heat the molding mold to 150-180°C, and then keeping it warm for 1-3h; cooling the molding mold to 40-60°C, and then keeping it warm for 22-26h. Specifically, the heating rate is 2-5°C / min.

[0048] like Figure 5 As shown, the present invention also provides a method for bonding a reverse and forward bidirectional pressure-bearing plugging cover of a rocket engine nozzle, the bonding method is used to bond the plugging cover 14 to the expansion section of the nozzle 15, and the bonding method comprises the following steps:

[0049] The bonding surface between the plugging cover 14 and the inner surface of the nozzle 15 is polished;

[0050] Prepare a high temperature resistant adhesive, and then use the high temperature resistant adhesive to bond the plugging cover 14 to the inner surface of the nozzle 15, and cure it at room temperature for 6 to 8 hours. The effective temperature range of the high temperature resistant adhesive is set to: -40 to 150°C. Specifically, the weight ratio of the high temperature resistant adhesive is set to 100 parts of epoxy resin, 5 to 10 parts of curing agent, 10 to 20 parts of polysulfide rubber powder, and 15 to 30 parts of mica.

[0051] Embodiment 1:

[0052] A nozzle plugging cap of a certain type of solid rocket engine is made of a fiber phenolic composite material, which requires that the reverse pressure of the plugging cap 14 is not less than 15MPa and the forward opening pressure is not less than 2.5MPa.

[0053] Design the plug cover 14 structure: Figure 1 and Figure 3As shown, the plugging cover 14 includes a plugging portion 141 and an adhesive portion 142. The plugging portion 141 is a spherical cap structure. The adhesive portion 142 is arranged near the edge of the convex spherical surface of the plugging portion 141. The spherical cap structure of the plugging portion 141 is provided with 11 load-bearing areas extending from the center to the surroundings, and the front and back surfaces of the 11 load-bearing areas are both provided as high-order equation surfaces of equivalent design profiles; the connection between the plugging portion 141 and the adhesive portion 142 is provided as a stiffness matching area 12, and the structure of the stiffness matching area 12 is a stiffness smooth transition structure with variable wall thickness, and the stiffness smooth transition structure with variable wall thickness is composed of its The central part extends toward the sealing part 141 and the bonding part 142 in sequence, and the inner and outer sides of the variable wall thickness stiffness smooth transition structure are smoothly connected with the inner and outer surfaces of the sealing part 141 and the bonding part 142 respectively, so as to form an integrated variable wall thickness ellipsoidal structure of the plugging cover 14, and there is no shear groove on the surface of the plugging cover 14; wherein, the thickness of the central part of the variable wall thickness stiffness smooth transition structure is 2.5 times the maximum thickness of the sealing part 141 and the bonding part 142; the effective bonding length of the bonding part 142 is 40 mm, and the effective bonding thickness of the bonding part 142 is 5 mm.

[0054] The plugging cover 14 is pressed and formed, which specifically includes the following steps:

[0055] a) according to the design structure of the designed plugging cover 14, calculate and weigh the molding material, which is the FB-1 modified filament bundle and short bundle fiber composite laminated injection phenolic resin material generated by the composite of filament bundle fiber, short bundle fiber and modified phenolic resin; wherein the modified phenolic resin is weighed and stirred evenly according to the weight ratio of 100 parts of phenolic resin, 15 parts of toughening filler, 3 parts of reinforcing filler, 3 parts of coupling agent and 0.5 parts of zinc stearate for standby use;

[0056] b) stacking the long filament tow fibers and the short filament tow fibers in sequence into a mold cavity of a forming mold according to a set stacking orientation requirement to form a substrate, and then locking the forming mold;

[0057] c) injecting the modified phenolic resin into the mold cavity of the molding mold through the injection port, so that the modified phenolic resin is evenly filled into the gaps and molding surface of the substrate, and solidified and molded;

[0058] d) heating the molding die to 90°C at a heating rate of 3°C / min, and then keeping the temperature for 1 hour;

[0059] e) Continue heating the molding die to 180°C at a heating rate of 3°C / min, and then keep the temperature for 2 hours;

[0060] f) Cooling the molding die to 60°C and then keeping it warm for 22 hours;

[0061] g) demoulding, taking out the product, and obtaining the plugging cover 14;

[0062] h) Check whether the product appearance and size meet the requirements.

[0063] The qualified plugging cap 14 is bonded and tested: first, the bonding surfaces of the plugging cap 14 and the inner surface of the nozzle 15 are polished respectively; then a high temperature resistant adhesive with an effective temperature range of -40 to 150°C is prepared. In this embodiment, the weight ratio of the high temperature resistant adhesive is set to 100 parts of epoxy resin, 10 parts of curing agent, 10 parts of polysulfide rubber powder and 15 parts of mica; then the plugging cap 14 is bonded to the inner surface of the nozzle 15 using the prepared high temperature resistant adhesive, and cured at room temperature for 6 hours to obtain the test piece. Then the test piece is connected to the gas pressure test bench, and the test pressure value of the gas pressure test bench is set to 15MPa according to the reverse pressure bearing size of the plugging cap 14, and the pressure holding time is 10s, and then the test is carried out in a safe environment. The test results meet the requirements and the reverse pressure bearing test of the plugging cap 14 is qualified. The opening pressure of the gas pressure test bench is set to 2.8 MPa, and a forward opening test is performed in a safe environment. The test results meet the design requirements, and the forward opening pressure test of the plugging cover 14 is qualified.

[0064] Embodiment 2:

[0065] The nozzle plugging cover of a certain type of solid rocket engine is made of fiber phenolic composite material, which requires the reverse pressure to be no less than 8MPa and the forward opening pressure to be no less than 2.0MPa.

[0066] Design of the blocking cover 14 structure: The difference between this embodiment and the first embodiment is that the effective bonding length of the bonding portion 142 is 30 mm, and the effective bonding thickness of the bonding portion 142 is 4 mm.

[0067] The plugging cover 14 is press-formed, and specifically includes the following steps: the difference between this embodiment and embodiment 1 is that the heat treatment conditions are different. The molding die is heated to 80°C at a heating rate of 5°C / min, and then kept warm for 1 hour; then the molding die is heated to 160°C at a heating rate of 5°C / min, and then kept warm for 3 hours; after the insulation is completed, the molding die is cooled to 50°C, and then kept warm for 24 hours.

[0068] The plugging cover 14 that has passed the inspection is bonded and tested: The difference between this embodiment and embodiment 1 is that the weight ratio of the high temperature resistant adhesive is set to 100 parts of epoxy resin, 12 parts of curing agent, 13 parts of polysulfide rubber powder and 18 parts of mica; then the plugging cover 14 is bonded to the inner surface of the nozzle 15 using the configured high temperature resistant adhesive, and cured at room temperature for 8 hours to obtain a test piece. Then the test piece is connected to the gas pressure test bench, and the test pressure value of the gas pressure test bench is set to 8MPa according to the reverse pressure bearing size of the plugging cover 14, and the pressure holding time is 10s. Then, the test is carried out in a safe environment, and the test results meet the requirements, and the reverse pressure bearing test of the plugging cover 14 is qualified. Then the opening pressure of the gas pressure test bench is set to 2.2MPa, and a forward opening test is carried out in a safe environment. The test results meet the design requirements, and the forward opening pressure test of the plugging cover 14 is qualified.

[0069] In the present invention, the above experimental results show that the plugging cap has the advantages of directional critical pressure blasting, high strength, low density, small volume, etc.; and by designing the stiffness matching area of ​​the plugging cap as a stiffness smooth transition structure with variable wall thickness and the stacking orientation requirements of the long filament bundle fibers and the short filament bundle fibers along the microscopic direction (arranged along the inner wall surface direction parallel to the mold cavity), the function of withstanding high reverse pressure and low forward pressure is achieved, so that there is no need to rely on shear grooves for blasting during the operation process, and it can meet the high-pressure, high-temperature, and high-speed gas impact ejection within 20MPa, and the forward opening pressure is designable (1MPa-8MPa), the weight of a single piece of opened fragments is small, and the product quality is stable. For example, the forward opening pressure of the plugging cap is consistent with the reverse pressure (the pressure bearing performance of different batches of products is stable and almost without deviation) and the reliability is high, which meets the preparation requirements of ejection rocket engines.

Claims

1. A rocket engine nozzle reverse and forward bidirectional pressure-bearing plugging cover, the plugging cover (14) being installed inside the expansion section of the nozzle (15), the plugging cover (14) comprising a plugging portion (141) and a bonding portion (142), wherein the plugging portion (141) is a spherical cap structure, and the bonding portion (142) is arranged near the edge of the convex spherical surface of the plugging portion (141), characterized in that: The spherical cap structure of the blocking portion (141) is provided with a plurality of load-bearing areas extending from the center to the periphery, and the front and back surfaces of the plurality of load-bearing areas are both provided as high-order equation surfaces of equivalent design profiles; The connection between the blocking portion (141) and the bonding portion (142) is provided as a rigidity matching area (12), the rigidity matching area (12) being a rigidity smooth transition structure with a variable wall thickness, the rigidity smooth transition structure with a variable wall thickness extending from its central portion toward the blocking portion (141) and the bonding portion (142) in sequence, and the inner and outer sides of the rigidity smooth transition structure with a variable wall thickness are smoothly butted with the inner and outer surfaces of the blocking portion (141) and the bonding portion (142) respectively, so as to form the blocking cover (14) of an integrated variable wall thickness ellipsoid structure, and the surface of the blocking cover (14) has no shear grooves; The material of the plugging cover (14) is a composite laminated injection phenolic resin material of FB-1 modified long filament bundles and short filament bundles, and the pressure-bearing function of the front and back sides is obtained by the orientation of the laminated filament bundles.

2. The rocket engine nozzle reverse and forward bidirectional pressure-bearing plugging cover according to claim 1 is characterized in that: The FB-1 modified filament bundle and short filament bundle fiber composite laminated injection phenolic resin material is composited and generated by filament bundle fibers, short filament bundle fibers and modified phenolic resin, wherein: The long filament bundle fibers and the short filament bundle fibers are stacked in a plurality of layers according to a set rule to form a substrate; the set rule is: according to the design strength of the plugging cover (14), the long filament bundle fibers are stacked in sequence along the center to both sides with a preset unit amount of the short filament bundle fibers according to the stacking orientation requirements in the microscopic direction by cross-weaving or overlapping connection; The modified phenolic resin is filled in the gaps and / or the molding surface of the substrate.

3. The rocket engine nozzle reverse and forward bidirectional pressure-bearing plugging cover according to claim 2 is characterized in that: The weight ratio of the modified phenolic resin is set as: 100 parts of phenolic resin, 10-15 parts of toughening filler, 2-5 parts of reinforcing filler, 2-5 parts of coupling agent, 0.5-1 part of zinc stearate.

4. The rocket engine nozzle reverse and forward bidirectional pressure-bearing plugging cover according to claim 1 is characterized in that: The thickness of the central portion of the variable wall thickness stiffness smooth transition structure is at least twice the thickness of the largest thickness between the blocking portion (141) and the bonding portion (142).

5. The rocket engine nozzle reverse and forward bidirectional pressure-bearing plugging cover according to claim 1 is characterized in that: The bonding surface length of the bonding portion (142) is set to 30 to 50 mm, and the bonding surface thickness of the bonding portion (142) is set to 3 to 5 mm.

6. A method for forming a reverse and forward bidirectional pressure-bearing plugging cover for a rocket engine nozzle, the method being applied to prepare the plugging cover (14) according to any one of claims 1 to 5, characterized in that: The molding method comprises the following steps: S1. According to the design structure of the plugging cover (14), weigh corresponding molding materials for use, wherein the molding materials include a preset unit amount of long filament fiber, short filament fiber and modified phenolic resin; S2, stacking the long filament fiber and the short filament fiber in sequence into a mold cavity of a forming mold according to a set stacking orientation requirement to form a substrate, and locking the forming mold; S3, injecting the modified phenolic resin into the mold cavity of the molding mold through the injection port, so that the modified phenolic resin is evenly filled into the gaps and / or molding surface of the substrate, and then subjecting the molding mold to heat treatment, cooling it to room temperature and demoulding it to obtain the plugging cover (14).

7. The method for forming a reverse and forward bidirectional pressure-bearing plugging cover for a rocket engine nozzle according to claim 6, characterized in that: In S3, the heat treatment comprises: S3-01, heating the molding die to 70-90° C., and then keeping the temperature for 0.8-1.2 h; S3-02, continue to heat the molding die to 150-180° C., and then keep the temperature for 1-3 hours; S3-03, cooling the molding die to 40-60°C, and then keeping the temperature for 22-26 hours.

8. The method for forming a reverse and forward bidirectional pressure-bearing plugging cover for a rocket engine nozzle according to claim 7, characterized in that: The heating rate in S3-01 and S3-02 is 2 to 5°C / min.

9. A method for bonding a reverse and forward bidirectional pressure-bearing plugging cover of a rocket engine nozzle, the method being used to bond the plugging cover (14) according to any one of claims 1 to 5 to the expansion section of the nozzle (15), characterized in that: The bonding method comprises the following steps: The bonding surfaces of the plugging cover (14) and the inner surface of the nozzle (15) are respectively polished; Preparing a high temperature resistant adhesive, and then using the high temperature resistant adhesive to bond the plugging cover (14) to the inner surface of the nozzle (15), and curing at room temperature for 6-8 hours; The effective temperature range of the high temperature resistant adhesive is set to: -40 to 150°C.

10. The method for bonding the reverse and forward bidirectional pressure-bearing plugging cover of the rocket engine nozzle according to claim 9, characterized in that: The weight ratio of the high temperature resistant adhesive is set as: 100 parts of epoxy resin, 5-10 parts of curing agent, 10-20 parts of polysulfide rubber powder, 15-30 parts of mica.

Images