A bladder core for a solid rocket motor and a method of making the same

Abstract

The application relates to a gas bag core for a solid rocket engine and a preparation method thereof, which comprises a gas bag body with a gas-tight cavity inside, a gas bag central shaft penetrating through the gas-tight cavity, both ends of the gas bag central shaft in the length direction extending out of the gas bag body, and the gas bag central shaft being coaxially arranged with the gas bag body, and a pressure stabilizing valve with a valve port communicating with the gas-tight cavity. By using the gas bag body as a core, the pressure stabilizing valve is used to inflate the gas bag body to form a gas bag core special for the solid rocket engine, the gas bag body is formed by inflation, the weight of the gas bag core is reduced, and when the gas bag core is used to manufacture the solid rocket engine, the pressure stabilizing valve can timely supplement air to the inside of the gas bag body to maintain the pressure, and the problems that the core for the solid rocket engine is heavy and it is difficult to realize the reuse while reducing the cost are solved.

Description

Technical Field

[0001] This application relates to the field of solid rocket motor manufacturing, specifically to a gasbag core mold for a solid rocket motor and its preparation method. Background Technology

[0002] In modern industrial manufacturing, especially in industries such as aerospace, automotive manufacturing, and precision instrument manufacturing, mandrels play a crucial role as a key component in the molding process. In the aerospace field, mandrels are mainly used for casting and injection molding of solid rocket motors. During the mandrel fabrication process, cavities or complex internal structures are formed inside the mandrel to ensure that the shape and dimensions of the solid rocket motor meet design requirements.

[0003] Currently, widely used core molds mainly include plaster core molds, sand core molds, and metal frame core molds. However, in practical use, plaster or sand core molds are heavy, making them difficult to use and transport. Furthermore, after the solid rocket motor is cast, demolding requires mechanical crushing or water flushing, thus limiting their single-use capability. Metal frame core molds are reusable, but their weight makes them difficult to use and transport, and they are also expensive. Each of these core molds has significant limitations, including their considerable weight, and it is difficult to achieve reusability while reducing costs, thus limiting their effectiveness and economy in specific application scenarios. Summary of the Invention

[0004] This application provides a gasbag core mold for solid rocket motors and its preparation method, which can solve the technical problems in the prior art where the core molds used for solid rocket motors are heavy and difficult to achieve reusability while reducing costs.

[0005] In a first aspect, a gasbag core mold for a solid rocket motor is provided, comprising: The airbag body has an airtight cavity inside; The airbag central shaft passes through the airtight cavity, and both ends of the airbag central shaft extend from the airbag body along its length, and the airbag central shaft is coaxially arranged with the airbag body. And a pressure regulating valve, wherein the valve port of the pressure regulating valve is connected to the airtight cavity.

[0006] In conjunction with the first aspect, in one implementation method, The pressure regulating valve is disposed on the central axis of the airbag, and an air delivery channel is provided on the central axis of the airbag along the length of the central axis of the airbag. The air delivery channel is connected to the airtight cavity and the pressure regulating valve.

[0007] In conjunction with the first aspect, in one embodiment, clamping blocks are provided on the central axis of the airbag at both ends of the airbag body, and the clamping blocks are detachably connected to the airbag body.

[0008] In conjunction with the first aspect, in one embodiment, the surface of the airbag body is provided with bolt holes, and a clamping bolt is provided on the clamping block, the clamping bolt being threadedly engaged with the bolt holes.

[0009] In conjunction with the first aspect, in one embodiment, the airbag body comprises, from the inside out, an airtight layer, a reinforcing layer, and an outer layer of the airbag, all integrally formed, and the airtight cavity is disposed within the airtight layer.

[0010] In conjunction with the first aspect, in one embodiment, a gasbag core mold for a solid rocket motor further includes: A heating element is disposed between the airtight layer and the reinforcing layer.

[0011] In conjunction with the first aspect, in one embodiment, the heating element includes: Multiple resistance wires are spaced apart along the airbag body.

[0012] Secondly, a method for preparing an airbag core mold is provided: It is used to prepare a gasbag core mold for a solid rocket motor as described in any one of the above, and includes the following steps: Prepare the airbag body; The central axis of the airbag is passed through the airbag body, and the pressure regulating valve is connected to the airtight cavity; Connect the air replenishment device to the pressure stabilizing valve to inflate the airbag body; The airbag body is heated and solidified to obtain an airbag core mold.

[0013] In conjunction with the second aspect, in one embodiment, the preparation of the airbag body includes: Prepare the airtight layer, pass the central axis of the airbag through the airtight layer, and form the airtight cavity inside the airtight layer; A heating element is laid outside the airtight layer, and the reinforcing layer and the outer layer of the airbag are sequentially prepared outside the heating element to obtain the airbag body.

[0014] In conjunction with the second aspect, in one embodiment, a method for preparing an airbag core mold further includes: Air tightness and folding tests were conducted on the airbag core mold.

[0015] The beneficial effects of the technical solution provided in this application include: by using the airbag body as a core mold, and using a pressure regulating valve to inflate the airbag body to form a dedicated airbag core mold for solid rocket motors, the weight of the airbag core mold is greatly reduced by inflating the airbag body. At the same time, when using the airbag core mold to manufacture solid rocket motors, the pressure regulating valve can replenish air into the airbag body in a timely manner to maintain pressure, which facilitates molding and reduces manufacturing costs. After the solid rocket motor is manufactured, the airbag body can be depressurized by using the pressure regulating valve, and it can be reused. This solves the problem in the prior art that the core molds used for solid rocket motors are currently heavy and difficult to achieve reusability while reducing costs. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A cross-sectional view of a gasbag core mold for a solid rocket motor provided in an embodiment of this application; In the diagram: 1. Airbag body; 11. Airtight layer; 111. Airtight cavity; 12. Reinforcing layer; 121. Reinforcing body; 13. Outer layer of airbag; 2. Central axis of airbag; 21. Air delivery channel; 22. Clamping block; 221. Clamping bolt; 3. Pressure regulating valve. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] This application provides a gasbag core mold for solid rocket motors and its preparation method, which can solve the problems in the existing technologies of solid rocket motor core molds, which are currently heavy and difficult to reusable while reducing costs.

[0020] Reference Figure 1This application discloses a cross-sectional view of a gasbag core mold for a solid rocket motor. The gasbag core mold includes a gasbag body 1, a gasbag central shaft 2, and a pressure regulating valve 3. The gasbag body 1 contains an airtight cavity 111. The gasbag body 1 is formed by inflation, significantly reducing the weight of the gasbag core mold. The gasbag central shaft 2 passes through the airtight cavity 111, and both ends of the central shaft 2 extend from the gasbag body 1 along its length. The central shaft 2 is coaxially arranged with the gasbag body 1 to more evenly drive the gas during subsequent solid rocket motor manufacturing. The airbag body 1 rotates; the valve port of the pressure regulating valve 3 is connected to the airtight cavity 111 so that the air pressure in the airtight cavity 111 can be balanced even when the airbag body 1 rotates at high speed during the solid rocket engine manufacturing process, which facilitates molding and reduces manufacturing costs; and after the solid rocket engine is manufactured and cured, the airbag body 1 can be depressurized, which facilitates the demolding of the solid rocket engine and allows it to be reused. This solves the problem that the core molds used in current solid rocket engines are heavy and difficult to reuse while reducing costs.

[0021] More specifically, to facilitate the connection of the pressure regulating valve 3 with other equipment in the operating environment, the pressure regulating valve 3 is specifically mounted on the central shaft 2 of the airbag. An air supply channel 21 is provided along the length of the central shaft 2, and the air supply channel 21 is connected to the airtight cavity 111 and the pressure regulating valve 3. This minimizes the impact of the connection on the rotation of the airbag body 1 when the operator connects the pressure regulating valve 3 to other pressure-stabilizing air supply equipment. In other embodiments, if the pressure regulating valve 3 does not require external connection to other equipment, it can be directly installed on the surface of the airbag body 1, ensuring the airtightness of the airtight cavity 111 while allowing the pressure regulating valve 3 to connect to the airtight cavity 111.

[0022] Furthermore, since the airbag central shaft 2 extends from both ends of the airbag body 1 along its length, in order to improve the airtightness of the airtight cavity 111, clamping blocks 22 are provided on the airbag central shaft 2 at both ends of the airbag body 1. The clamping blocks 22 can press and seal the connection between the airbag central shaft 2 and the airbag body 1, and can also provide a clamping station for other operating equipment to clamp the airbag central shaft 2 during the subsequent solid rocket engine manufacturing process.

[0023] The clamping block 22 is detachably connected to the airbag body 1 to facilitate the disassembly of the clamping block 22 and subsequent demolding of the airbag body 1. More specifically, in one embodiment of this application, bolt holes are provided on the surface of the airbag body 1, and clamping bolts 221 are threaded onto the clamping block 22, with the clamping bolts 221 threaded into the bolt holes. Tightening the clamping bolts 221 establishes the connection between the clamping block 22 and the airbag body 1, allowing the clamping block 22 to clamp the airbag body 1 from both ends along its length and to seal the gap between the airbag central axis 2 and the airbag body 1. The structure is simple and easy to use.

[0024] In order to further improve the airtightness of the airbag body 1 and the structural strength of the airbag body 1 itself, the airbag body 1 includes, from the inside to the outside, an airtight layer 11, a reinforcing layer 12 and an airbag outer layer 13, which are made as one piece, and an airtight cavity 111 is formed in the airtight layer 11.

[0025] Specifically, the airtight layer 11 can be made of flexible rubber. Flexible rubber has excellent flexibility and wear resistance, thus maintaining the good airtightness of the airtight cavity 111 while also ensuring sufficient strength of the airtight layer 11. As the core sealing structure of the airtight cavity 111, the material selection for the airtight layer 11 needs to comprehensively consider both sealing performance and structural durability. Specifically, flexible materials such as styrene-butadiene rubber (SBR), chloroprene rubber (CR), or silicone rubber (VMQ) exhibit an elastic modulus range of 0.5-3.0 MPa due to their unique molecular chain structure, and can generate 40%-70% elastic deformation under pressure, effectively filling the microscopic defects of the contact surface. The three-dimensional cross-linked network structure formed through the vulcanization process not only gives the material an adjustable Shore A hardness range of over 90°, but also achieves an elongation at break of 500%-800%, ensuring a stable sealing interface during cyclic compression-rebound processes. Furthermore, the introduction of nano-sized carbon black (particle size 20-50nm) or silica (specific surface area 150-200m² / g) reinforcing phases into the composite formulation can increase the wear resistance index to 2-3 times that of traditional rubber, with a thickness loss rate of less than 5% after several friction cycles. This material design enables the compressive strength of the airtight layer 11 to be less than 15% in the operating range of -40℃ to 120℃. Combined with a 30-50μm thick fluorosilicone coating on the surface, the gas permeability is further reduced, meeting the stringent requirements of the airtight layer 11 for long-term airtightness.

[0026] The reinforcing layer 12 is specifically composed of several reinforcing bodies 121 interlaced. In the manufacturing process of the reinforcing layer 12, a winding process is used to wind the reinforcing bodies 121 to the outside of the airtight layer 11 via helical or circumferential winding. The strength of the reinforcing layer 12 is increased or decreased by changing the winding thickness to meet the strength requirements of the gasbag core mold in different solid rocket motor manufacturing processes. The reinforcing bodies 121 are made of continuous fibers. In one embodiment of this application, the continuous fibers can be glass fibers with high strength, good corrosion resistance, and heat resistance; carbon fibers with extremely high strength and modulus while being lightweight; or aramid fibers with high strength, high modulus, good heat resistance, and chemical corrosion resistance. The specific material selection for the reinforcing bodies 121 can be flexibly changed according to the strength requirements of the gasbag core mold in different solid rocket motor manufacturing processes.

[0027] The outer layer 13 of the airbag, like the airtight layer 11, is made of flexible rubber. During the manufacturing process of the outer layer 13, a spraying process can be used to apply the flexible rubber to the surface of the reinforcing layer 12 to maintain the dimensions of the airbag core mold. This not only meets the aesthetic requirements of the airbag core mold but also provides additional airtight strength and flexibility protection to the surface of the reinforcing layer 12, making it more convenient to use. During spraying, the thickness of the spray coating on the outer layer 13 can be increased, and bolt holes can be made in the outer layer 13 to engage with the clamping bolts 221 on the clamping blocks 22 at both ends of the airbag central shaft 2. In one embodiment of this application, the spraying process uses a multi-axis robotic arm equipped with a high-pressure airless spray gun to construct a coating layer with a gradient thickness of 0.8-1.2mm on the surface of the reinforcing layer 12 through a three-stage cross-spraying method. The first bottom spray focuses on filling the fiber gaps of the reinforcing layer 12, while the subsequent two sprays form a uniform rubber matrix by alternating gun paths at 45° and 135° to improve the airtightness of the surface of the reinforcing layer 12.

[0028] Furthermore, to further extend the service life of the airbag core mold components, the airbag central shaft 2 can be made of rigid metal materials, such as stainless steel or aluminum alloy, which have high strength. This reduces the likelihood of frequent replacements of the airbag central shaft 2, thereby increasing the service life of a single airbag core mold. Compared to traditional engineering plastics, the dense grain structure formed by rolling or forging processes in these metal materials significantly improves the bending strength and fatigue resistance of the airbag central shaft 2, making it less prone to plastic deformation under cyclic loads. Taking 304 stainless steel as an example, its microstructure after solution strengthening treatment can form a stable dislocation network. Combined with the oxide film formed by surface passivation treatment, this can simultaneously enhance the corrosion resistance of the shaft in humid environments or weak acid and weak alkali media. For applications with high lightweight requirements, 6000 series aluminum alloys, through a combination of age hardening and anodizing processes, can effectively suppress stress corrosion cracking while maintaining high specific strength. The application of these materials allows the airbag central shaft 2 to maintain the geometric accuracy of the axis even when subjected to long-term radial impact loads, thereby reducing the risk of seal failure due to shaft wear or deformation. In addition, the matching design of the thermal expansion coefficients of the metal materials and the flexible components of the airbag can effectively alleviate the interfacial stress generated by temperature cycling and further extend the service life of the components under wide temperature range conditions.

[0029] Furthermore, to further extend the service life of the airbag core mold components, the airbag central shaft 2 can be made of rigid metal materials, such as stainless steel or aluminum alloy, which have high strength. This reduces the likelihood of frequent replacements of the airbag central shaft 2, thereby increasing the service life of a single airbag core mold. Compared to traditional engineering plastics, the dense grain structure formed by rolling or forging processes in these metal materials significantly improves the bending strength and fatigue resistance of the airbag central shaft 2, making it less prone to plastic deformation under cyclic loads. Taking 304 stainless steel as an example, its microstructure after solution strengthening treatment can form a stable dislocation network. Combined with the oxide film formed by surface passivation treatment, this can simultaneously enhance the corrosion resistance of the shaft in humid environments or weak acid and weak alkali media. For applications with high lightweight requirements, 6000 series aluminum alloys, through a combination of age hardening and anodizing processes, can effectively suppress stress corrosion cracking while maintaining high specific strength. The application of these materials allows the airbag central shaft 2 to maintain the geometric accuracy of the axis even when subjected to long-term radial impact loads, thereby reducing the risk of seal failure due to shaft wear or deformation. In addition, the matching design of the thermal expansion coefficients of the metal materials and the flexible components of the airbag can effectively alleviate the interfacial stress generated by temperature cycling and further extend the service life of the components under wide temperature range conditions.

[0030] To facilitate high-temperature curing of the airbag core mold during production, this application also includes a heating element disposed on the airtight layer 11. Specifically, in this application, the heating element comprises resistance wires, multiple of which are spaced apart along the axial direction of the airbag body 1. The leads of the resistance wires pass through the central shaft 2 of the airbag, making it easy for operators to connect the resistance wires to a power source, thereby heating the airbag core mold from the inside and assisting in the simultaneous high-temperature curing of the airbag core mold from the inside and outside. Furthermore, due to the flexible structure of the resistance wires, neither the airtightness nor the folding performance of the flexible core mold is affected. When laying the resistance wires, they can be placed between the airtight layer 11 and the reinforcing layer 12. In other embodiments, the resistance wires can also be laid on the inner wall of the airtight layer 11. In addition, for embodiments without additional heating elements, high-temperature gas is injected directly into the airbag core mold through the pressure regulating valve 3, thereby providing auxiliary heating of the airbag core mold from the inside.

[0031] Based on the gasbag core mold for a solid rocket motor provided in this application, this application also proposes a method for preparing the gasbag core mold, which includes the following steps: S1: Prepare the airbag body 1; Specifically, the airbag body 1 includes an airtight layer 11, a reinforcing layer 12, and an outer layer 13, and its manufacturing process also includes: S101: Prepare the airtight layer 11, pass the airbag central shaft 2 through the airtight layer 11, and form the airtight cavity 111 inside the airtight layer 11; In one embodiment of this application, the airtight layer 11 can be made of flexible rubber. Flexible rubber has excellent flexibility and wear resistance, thus enabling the airtight layer 11 to have sufficient strength while maintaining good airtightness of the airtight cavity 111. In other embodiments, other flexible materials such as styrene-butadiene rubber, neoprene rubber, or silicone rubber can also be used.

[0032] S102: A heating element is laid on the outside of the airtight layer 11, and the reinforcing layer 12 and the outer layer 13 of the airbag are sequentially prepared on the outside of the heating element to obtain the airbag body 1.

[0033] In one embodiment of this application, the heating element is specifically selected as a resistance wire. According to the actual working conditions, the resistance wire is laid on the outer or inner wall of the airtight layer 11, and then the reinforcing layer 12 and the outer layer 13 of the airbag are prepared.

[0034] In this embodiment, the reinforcement layer 12 is specifically composed of several reinforcing bodies 121 interlaced. During the manufacturing process of the reinforcement layer 12, a winding process is used to wind the reinforcing bodies 121 to the outside of the airtight layer 11 via helical or circumferential winding. The strength of the reinforcement layer 12 is increased or decreased by changing the winding thickness to meet the strength requirements of the gasbag core mold in different solid rocket motor manufacturing processes. The outer layer 13 of the gasbag is also made of flexible rubber, just like the airtight layer 11. During the manufacturing process of the outer layer 13, a spraying process can be used to spray the flexible rubber onto the surface of the reinforcement layer 12 to maintain the appearance and dimensions of the gasbag core mold. While meeting the aesthetic requirements of the gasbag core mold, this process also provides additional airtight strength and flexibility protection to the surface of the reinforcement layer 12, making it more convenient to use.

[0035] S2: Pass the airbag central shaft 2 through the airbag body 1 and connect the pressure stabilizing valve 3 to the airtight cavity 111; To further improve the service life of airbag core mold components, the airbag central shaft 2 can be made of rigid metal materials, such as stainless steel or aluminum alloy, which have high strength. This reduces the possibility of frequent replacement of the airbag central shaft 2, thereby improving the service life of a single airbag core mold.

[0036] S3: Connect the air replenishment device to the pressure regulating valve 3 to inflate the airbag body 1; S4: Heat the airbag body 1 and solidify it to obtain the airbag core mold.

[0037] When heating the airbag body 1, the airbag body 1 can be heated inside and out simultaneously with the help of heating elements, or high-temperature gas can be directly injected into the airbag body 1 through the pressure regulating valve 3 to achieve internal heating of the airbag core mold.

[0038] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0039] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0040] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A gasbag core mold for a solid rocket motor, characterized in that, It includes: The airbag body (1) has an airtight cavity (111) inside. The airbag central shaft (2) passes through the airtight cavity (111). Both ends of the airbag central shaft (2) in the length direction extend from the airbag body (1), and the airbag central shaft (2) is coaxial with the airbag body (1). And a pressure regulating valve (3), the valve port of which is connected to the airtight cavity (111).

2. The gasbag core mold for a solid rocket motor according to claim 1, characterized in that: The pressure regulating valve (3) is disposed on the central axis (2) of the airbag. An air delivery channel (21) is provided on the central axis (2) of the airbag along the length direction of the central axis (2). The air delivery channel (21) is connected to the airtight cavity (111) and the pressure regulating valve (3).

3. The gasbag core mold for a solid rocket motor according to claim 1, characterized in that: Clamping blocks (22) are provided on the central shaft (2) of the airbag and at both ends of the airbag body (1). The clamping blocks (22) are detachably connected to the airbag body (1).

4. A gasbag core mold for a solid rocket motor according to claim 3, characterized in that: The airbag body (1) has bolt holes on its surface, and clamping bolts (221) are threaded through the clamping block (22). The clamping bolts (221) are threaded into the bolt holes.

5. A gasbag core mold for a solid rocket motor according to claim 1, characterized in that: The airbag body (1) includes, from the inside out, an airtight layer (11), a reinforcing layer (12), and an airbag outer layer (13) that are integrally formed, and the airtight cavity (111) is disposed in the airtight layer (11).

6. A gasbag core mold for a solid rocket motor according to claim 5, characterized in that, It also includes: A heating element is disposed on the airtight layer (11).

7. A gasbag core mold for a solid rocket motor according to claim 6, characterized in that, The heating element includes: Multiple resistance wires are provided at intervals along the axial direction of the airbag body (1).

8. A method for preparing an airbag core mold, characterized in that: It is used to prepare a gasbag core mold for a solid rocket motor as described in any one of claims 1-7, and includes the following steps: Prepare the airbag body (1); The airbag central shaft (2) is passed through the airbag body (1), and the pressure regulating valve (3) is connected to the airtight cavity (111); Connect the air replenishment device to the pressure regulating valve (3) to inflate the airbag body (1); The airbag body (1) is heated and solidified to obtain an airbag core mold.

9. A method for preparing an airbag core mold according to claim 8, characterized in that: The preparation of the airbag body (1) includes: Prepare the airtight layer (11), pass the central shaft (2) of the airbag through the airtight layer (11), and form the airtight cavity (111) inside the airtight layer (11). A heating element is laid on the outside of the airtight layer (11), and the reinforcing layer (12) and the outer layer (13) of the airbag are sequentially prepared on the outside of the heating element to obtain the airbag body (1).

10. A method for preparing an airbag core mold according to claim 8, characterized in that, It also includes: Air tightness and folding tests were conducted on the airbag core mold.

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