A gas generator combustion chamber shell and a manufacturing method thereof

Abstract

This invention proposes a combustion chamber shell for a gas generator and its manufacturing method, belonging to the field of composite material shell technology. It solves the problem of excessive weight in existing metal-structured gas generators due to their thicker walls. It includes a front connector, an upper baffle plate, a wall support, a lower baffle plate, a rear connector, an upper mold, and a lower mold. The upper and lower molds are connected; the front connector is connected to the top of the upper mold, and the rear connector is connected to the bottom of the lower mold. The upper baffle plate is disposed within the upper mold, and the lower baffle plate is disposed within the lower mold. The wall support is installed on the inner wall of the lower mold and is positioned between the upper and lower baffle plates. It is primarily used for manufacturing combustion chamber shells.

Description

Technical Field

[0001] This invention belongs to the field of composite material shell technology, and in particular relates to a combustion chamber shell for a gas generator and its manufacturing method. Background Technology

[0002] A gas generator is a gas production device that generates high-temperature, high-pressure gas by burning a certain proportion of fuel and oxidant to meet specific purposes. It mainly includes a combustion chamber, ignition device, propellant, and nozzle. Most components of current gas generators are made of metal and formed by metal welding. As the place where gas is generated, the combustion chamber must have performance requirements such as high pressure resistance, high temperature resistance, and resistance to high-temperature gas erosion. Therefore, the manufacturing of the combustion chamber requires multiple methods such as casting, assembly, welding, and machining to ensure the airtightness, high temperature resistance, and external dimensions of the product. After completion, the welds need to be inspected for flaws, and the combustion chamber needs to be tested for airtightness and water pressure. The manufacturing requirements and costs are relatively high. Due to the isotropic nature of metal materials, for pressure vessels, in order to withstand the internal pressure in all directions during operation, metal structure gas generators are often designed with thick walls, making them bulky and heavy. The overall weight of the combustion chamber is relatively heavy, which limits its use in some scenarios. Summary of the Invention

[0003] In view of this, the present invention aims to provide a combustion chamber shell for a gas generator and a method for manufacturing the same, in order to solve the problem that the existing metal structure gas generators have a relatively thick wall design, resulting in an overall heavy weight of the combustion chamber.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A combustion chamber housing for a gas generator includes a front connector, an upper baffle plate, a wall support, a lower baffle plate, a rear connector, an upper mold, and a lower mold. The upper mold and the lower mold are connected. The front connector is connected to the top of the upper mold, and the rear connector is connected to the bottom of the lower mold. The upper baffle plate is disposed inside the upper mold, and the lower baffle plate is disposed inside the lower mold. The wall support is installed on the inner wall of the lower mold and is disposed between the upper baffle plate and the lower baffle plate.

[0006] Furthermore, the upper and lower mold halves are provided with heat insulation layers on their outer sides, and a composite material layer is provided outside the heat insulation layers.

[0007] Furthermore, a connecting flange is fitted onto the outer side of the lower half mold, and a flat key is provided between the bottom of the lower half mold and the lower baffle plate.

[0008] A method for manufacturing a combustion chamber shell of a gas generator, comprising the following steps:

[0009] Step 1: Assemble the upper and lower medicine baffles with the wall support to form a metal frame structure and fix it with bolts;

[0010] Step 2: Prepare the sand core mold for the embedded metal frame structure;

[0011] Step 3: Position and assemble the front connector, rear connector, sand core mold, and winding mold;

[0012] Step 4: Prepare an insulating layer on the outer surface of the mandrel;

[0013] Step 5: Wet winding of carbon fiber / epoxy resin onto the surface of the insulation layer is performed for limiting and winding, and the composite material structure layer is cured in stages.

[0014] Step 6: Fix the connecting flange on the connecting flange positioning fixture, push the positioning fixture to the mating step from the front end of the mandrel, and fix it with the clamping plate;

[0015] Step 7: Using the winding spindle as a reference, complete the dimensions of the connecting flange end face, cylindrical surface, and end face opening position on a CNC lathe;

[0016] Step 8: After removing the winding mandrel, fill the inside of the shell with water to demold it, and dry it to obtain the final shell.

[0017] Furthermore, in step 2, the sand is sieved through a 30-60 mesh screen and set aside. 5±1kg of clean water is poured into a container and heated to 80±10℃. 2±0.5kg of polyvinyl alcohol is poured in while stirring at a ratio of 1:3-4. After the polyvinyl alcohol is completely dissolved, it is cooled and set aside. The sand and the prepared polyvinyl alcohol solution are thoroughly mixed at a ratio of 1:5-6 and wrapped in plastic sheeting for later use.

[0018] Furthermore, in step 2, the upper and lower halves of the sand core mold with unequal heights are made in two steps. The upper half of the mold has an embedded upper baffle plate, and the lower half of the mold has an embedded lower baffle plate and a wall support. The sand mixed with adhesive is loaded into the mold and compacted. When making the lower half of the mold, the wall support is fixed to the side wall of the sand core mold by positioning pins to determine the axial height. When making the upper half of the mold, the axial height of the upper baffle plate is determined by the positioning surface of the mold. The upper and lower halves of the mold are cured in stages. The curing regime is 100-120℃ and the time is 8h±2h. After removing the upper and lower halves of the mold, the length of the upper and lower halves of the mold is determined by grinding the half mold and the stop. The sand core mold after being assembled is sent to the curing oven for baking. The curing regime is 100-120℃ and the time is 8h±2h.

[0019] Furthermore, after the sand core mold is closed in step 3, it is inserted into the winding mandrel. A positioning step is set on the mandrel to achieve axial positioning of the sand core mold. Circumferential positioning is confirmed by the positioning key set on the shaft. The front and rear joints are fixed to the mandrel through the front and rear joint positioning sleeves. Both the front and rear joints are fixed to the mandrel through the front and rear joint positioning sleeves.

[0020] Furthermore, in step 4, before covering, a EPDM film of the appropriate thickness is pre-rolled, and a cutting sample is made according to the unfolded surface of the shell and the nozzle, and the film is prepared accordingly.

[0021] Furthermore, in step 5, after uniformly mixing epoxy resin and curing agent at a mass ratio of 2:1, the fibers are wound with a winding tension of 40N-65N. During winding, the winding angles are alternated between ±25°-30° and 90°. After winding, the fibers are cured in three stages with a heating rate of 1-2℃ / min and a curing regime of 90℃±5℃ for a curing time of 6h±1h.

[0022] Furthermore, in step 6, after circumferentially winding the outer side of the connecting flange, the shell is cured and molded. The heating rate is 1-2℃ / min, the curing regime is 140℃±10℃, and the curing time is 8h±1h. After curing, the shell is allowed to cool naturally to room temperature along with the molding fixture, and then the connecting flange fixture is removed.

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

[0024] 1. This invention, through the designability of fiber winding, reduces the overall mass of the combustion chamber by more than 50% while meeting the operating pressure requirements of the combustion chamber; at the same time, compared with metal combustion chambers, it reduces mold manufacturing costs and testing costs.

[0025] 2. This invention incorporates a metal frame structure within a sand core mold, ensuring that the metal frame structure remains within the composite material shell after demolding, thus meeting the requirements for subsequent propellant loading and securing. The combustion chamber of the gas generator produced using this invention has passed various tests, exhibiting a burst pressure greater than 35 MPa, thus meeting design and subsequent usage requirements. Attached Figure Description

[0026] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0027] Figure 1 This is a schematic diagram of the structure of a combustion chamber shell for a gas generator;

[0028] Figure 2 This is a schematic diagram of the prepared sand core mold.

[0029] 1-Front connector, 2-Composite material layer, 3-Insulation layer, 4-Upper baffle plate, 5-Wall support, 6-Connecting flange, 7-Lower baffle plate, 8-Rear connector, 9-Upper mold half, 10-Lower mold half, 11-Flat key. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other, and the described embodiments are only some embodiments of the present invention, not all embodiments.

[0031] Specific implementation method one: See Figure 1-2 This embodiment describes a combustion chamber shell for a gas generator, comprising a front connector 1, an upper baffle plate 4, a wall support 5, a lower baffle plate 7, a rear connector 8, an upper mold 9, and a lower mold 10. The upper mold 9 is connected to the lower mold 10. The front connector 1 is connected to the top end of the upper mold 9, and the rear connector 8 is connected to the bottom end of the lower mold 10. The upper baffle plate 4 is disposed inside the upper mold 9, and the lower baffle plate 7 is disposed inside the lower mold 10. The wall support 5 is installed on the inner wall of the lower mold 10 and is positioned between the upper baffle plate 4 and the lower baffle plate 7. A heat insulation layer 3 is provided on the outer side of the upper mold 9 and the lower mold 10, and a composite material layer 2 is provided outside the heat insulation layer 3. A connecting flange 6 is sleeved on the outer side of the lower mold 10, and a flat key 11 is provided between the bottom of the lower mold 10 and the lower baffle plate 7.

[0032] like Figure 1 As shown, the parameters of the front and rear joints, insulation layer 3, internal metal frame structure, and composite fiber winding layer were first designed and optimized to determine the overall molding scheme. Based on the size, weight, and fixing requirements of the propellant charge, the structural forms of the upper and lower baffle plates were designed, the load-bearing capacity of the wall support 5 was checked, the thickness of the film covering was designed according to the requirements of insulation layer 3, and the number of fiber winding layers and reinforcement method were determined based on the working pressure of the combustion chamber.

[0033] like Figure 2 As shown, limited by the opening sizes of the front and rear joints of the combustion chamber shell, a soluble sand core mold with an internally embedded metal frame structure was designed to meet the requirements for loading and fixing the propellant grain. While satisfying the tension requirements of fiber winding and the dimensional accuracy of the combustion chamber shell, the metal frame structure for loading the propellant grain was simultaneously completed inside the combustion chamber. Furthermore, the raw materials and costs for making the sand core mold are low, and demolding only requires rinsing with water, making the process simple. By embedding the metal frame structure within the sand core mold, the metal frame structure remains within the composite material shell after demolding, which can meet the subsequent requirements for propellant grain installation and fixing. The gas generator combustion chamber prepared by this invention passed various tests, with a burst pressure greater than 35 MPa, meeting the design and subsequent use requirements.

[0034] Specific Implementation Method Two: A method for manufacturing a combustion chamber shell of a gas generator, comprising the following steps:

[0035] Step 1: Assemble the upper medicine baffle 4 and the lower medicine baffle 7 with the wall support 5 into a metal frame structure and fix them with bolts;

[0036] Step 2: Prepare the sand core mold for the embedded metal frame structure. Use a 30-60 mesh sieve to sieve the sand and set it aside. Pour 5±1 kg of water into a container and heat it to 80±10℃. While stirring, pour in 2±0.5 kg of polyvinyl alcohol at a ratio of 1:3-4. After the polyvinyl alcohol is completely dissolved, cool it and set it aside. Mix the sand and the prepared polyvinyl alcohol solution thoroughly at a ratio of 1:5-6 and wrap it in plastic wrap for later use.

[0037] The upper mold 9 and the lower mold 10, which are of unequal height, are made in two steps. The upper mold 9 is pre-embedded with an upper baffle plate 4, and the lower mold 10 is pre-embedded with a lower baffle plate 7 and a wall support 5. The sand mixed with adhesive is loaded into the mold and compacted. When making the lower mold 10, the wall support 5 is fixed to the side wall of the sand core mold by positioning pins to determine the axial height. When making the upper mold 9, the axial height of the upper baffle plate 4 is determined by the positioning surface of the mold. The upper and lower molds are cured in stages. The curing regime is 100-120℃ and the time is 8h±2h. After the upper and lower molds are removed, the length of the upper and lower molds is determined by grinding the half molds and the stop. The sand core mold after being assembled is sent to the curing oven for baking. The curing regime is 100-120℃ and the time is 8h±2h.

[0038] Step 3: Position and assemble the front connector 1, rear connector 8, sand core mold and winding mold. After the mold is closed, the sand core mold is inserted into the winding mandrel. The mandrel is equipped with positioning steps to achieve axial positioning of the sand core mold. Circumferential positioning is confirmed by the positioning key on the shaft. The front and rear connectors are fixed to the mandrel through the front and rear connector positioning sleeves. Both the front connector 1 and the rear connector 8 are fixed to the mandrel through the front and rear connector positioning sleeves.

[0039] Step 4: Prepare the heat insulation layer 3 on the outer surface of the core mold. Before covering, roll out the EPDM film of the appropriate thickness. Make a cutting sample according to the unfolded surface of the shell and the nozzle, and prepare the film according to the sample.

[0040] Step 5: Wet winding of carbon fiber / epoxy resin onto the surface of insulation layer 3 is performed with limited positioning. The composite material structure layer is formed by curing in stages. After uniform mixing of epoxy resin and curing agent by mass ratio of 2:1, the fibers are wound with a winding tension of 40N-65N. During winding, the winding angle is alternated between ±25°-30° and 90°. After winding, the fiber is cured in three stages with a heating rate of 1-2℃ / min and a curing regime of 90℃±5℃ for a curing time of 6h±1h.

[0041] Step 6: Fix the connecting flange 6 on the connecting flange positioning fixture, push the positioning fixture to the mating step from the front end of the mandrel, fix it with the clamping plate, and then perform circumferential winding on the outside of the connecting flange 6. Then, perform shell curing and molding. The heating rate is 1-2℃ / min, the curing regime is 140℃±10℃, and the curing time is 8h±1h. After curing, the shell will naturally cool down to room temperature with the molding fixture, and then the connecting flange 6 fixture will be removed.

[0042] Step 7: Using the winding spindle as a reference, complete the dimensions of the connecting flange end face, cylindrical surface, and end face opening position on a CNC lathe;

[0043] Step 8: After removing the winding mandrel, fill the inside of the shell with water to demold it, and dry it to obtain the final shell.

[0044] The manufacturing method of this combustion chamber shell, through the designability of fiber winding, reduces the overall mass of the combustion chamber by more than 50% while meeting the operating pressure requirements of the combustion chamber; at the same time, compared with metal combustion chambers, it reduces mold manufacturing costs and testing costs.

[0045] The embodiments of the present invention disclosed above are merely illustrative of the invention. These embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A combustion chamber shell for a gas generator, characterized in that: It includes a front connector (1), an upper baffle plate (4), a wall support (5), a lower baffle plate (7), a rear connector (8), an upper mold (9), and a lower mold (10). The upper mold (9) is connected to the lower mold (10). The front connector (1) is connected to the top of the upper mold (9), and the rear connector (8) is connected to the bottom of the lower mold (10). The upper baffle plate (4) is located inside the upper mold (9), and the lower baffle plate (7) is located inside the lower mold (10). Inside the mold (10), the wall support (5) is installed on the inner wall of the lower half mold (10). The wall support (5) is located between the upper baffle plate (4) and the lower baffle plate (7). The upper half mold (9) and the lower half mold (10) are provided with an insulation layer (3). The insulation layer (3) is provided with a composite material layer (2). The carbon fiber / epoxy resin is wet-wound onto the surface of the insulation layer (3) for limiting winding, and then cured in stages to form a composite material structure layer.

2. The combustion chamber shell of a gas generator according to claim 1, characterized in that: Connecting flanges (6) are installed on both sides of the lower half mold (10), and a flat key (11) is provided between the bottom of the lower half mold (10) and the lower baffle plate (7).

3. A method for manufacturing a combustion chamber shell of a gas generator as described in claim 1, characterized in that: It includes the following steps: Step 1: Assemble the upper medicine baffle (4) and the lower medicine baffle (7) with the wall support (5) into a metal frame structure and fix them with bolts; Step 2: Prepare the sand core mold for the embedded metal frame structure; Step 3: Position and assemble the front connector (1), rear connector (8), sand core mold, and winding mold; Step 4: Prepare an insulating layer (3) on the outer surface of the core mold; Step 5: Wet winding of carbon fiber / epoxy resin onto the surface of the insulation layer (3) is performed for limiting winding, and the composite material structure layer is cured in stages. Step 6: Fix the connecting flange (6) on the connecting flange positioning fixture, push the positioning fixture to the mating step from the front end of the mandrel, and fix it with the clamping plate; Step 7: Using the winding spindle as a reference, complete the dimensions of the connecting flange end face, cylindrical surface, and end face opening position on a CNC lathe; Step 8: After removing the winding mandrel, fill the inside of the shell with water to demold it, and dry it to obtain the final shell.

4. The method for manufacturing a combustion chamber shell of a gas generator according to claim 3, characterized in that: In step 2, sieve the sand through a 30-60 mesh screen and set aside. Pour 5±1 kg of water into a container and heat it to 80±10℃. While stirring, pour in 2±0.5 kg of polyvinyl alcohol at a ratio of 1:3-4. After the polyvinyl alcohol is completely dissolved, cool it and set aside. Mix the sand and the prepared polyvinyl alcohol solution thoroughly at a ratio of 1:5-6 and wrap it in plastic wrap for later use.

5. A method for manufacturing a combustion chamber shell of a gas generator according to claim 4, characterized in that: In step 2, the upper half mold (9) and the lower half mold (10) of the sand core mold with different heights are made in two steps. The upper half mold (9) is pre-embedded with the upper baffle plate (4), and the lower half mold (10) is pre-embedded with the lower baffle plate (7) and the wall support (5). The sand mixed with the adhesive is loaded into the mold and compacted. When the lower half mold (10) is made, the wall support (5) is fixed to the side wall of the sand core mold by the positioning pin to determine the axial height. When the upper half mold (9) is made, the axial height of the upper baffle plate (4) is positioned by the positioning surface of the mold. The upper and lower half molds are cured in stages. The curing temperature is 100-120℃ and the time is 8h±2h. After the upper and lower half molds are taken out, the length of the upper and lower half molds is determined by grinding the half mold and the stop. The sand core mold after being molded is sent into the curing oven for baking. The curing temperature is 100-120℃ and the time is 8h±2h.

6. A method for manufacturing a combustion chamber shell of a gas generator according to claim 3, characterized in that: After the sand core mold is completed in step 3, it is inserted into the winding mandrel. A positioning step is set on the mandrel to realize the axial positioning of the sand core mold. The circumferential positioning is confirmed by the positioning key set on the shaft. The front and rear joints are fixed to the core mold by the front and rear joint positioning sleeves. The front joint (1) and the rear joint (8) are both fixed to the core mold by the front and rear joint positioning sleeves.

7. A method for manufacturing a combustion chamber shell of a gas generator according to claim 3, characterized in that: Step 4: Before coating, roll out EPDM film of the appropriate thickness, make a cutting sample according to the unfolded surface of the shell and nozzle, and prepare the film accordingly.

8. A method for manufacturing a combustion chamber shell of a gas generator according to claim 3, characterized in that: Step 5: Mix epoxy resin and curing agent in a mass ratio of 2:1 until homogeneous, then wind the fibers. The winding tension is 40N-65N. During winding, alternate between winding angles of ±25°-30° and 90°. After winding, cure in three stages. The heating rate is 1-2℃ / min, the curing regime is 90℃±5℃, and the curing time is 6h±1h.

9. A method for manufacturing a combustion chamber shell of a gas generator according to claim 3, characterized in that: Step 6: After circumferentially winding the outer side of the connecting flange (6), the shell is cured and molded. The heating rate is 1-2℃ / min, the curing regime is 140℃±10℃, and the curing time is 8h±1h. After curing, the shell is naturally cooled to room temperature with the molding fixture, and then the connecting flange (6) fixture is removed.

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