Composite gas cylinder support structure and machining method thereof

Abstract

The invention relates to the technical field of spaceflight high-pressure gas cylinder matching structures and machining, and discloses a composite gas cylinder support structure and a machining method thereof.The composite gas cylinder support structure comprises a composite gas cylinder, the composite gas cylinder comprises a titanium alloy TA2 lining, a carbon fiber winding reinforcing layer and a support, and the support is a TC4 titanium alloy integral support; and the titanium alloy TA2 lining is formed by welding an upper half shell and a lower half shell through electron beams by adopting a plug-in structure. Compared with the traditional technology, the composite gas cylinder support structure and the processing method thereof have the following advantages that the integral support design is matched with the integrated connection mode of the carbon fiber winding fixing layer, mechanical / welding connection of a traditional titanium alloy support is replaced, and the connection strength and the overall rigidity of the support and a gas cylinder are improved; the design of the flat ellipsoid end socket avoids the adverse effect of circumferential compression stress on the pressure vessel, and the precise design of 16 rings and 6 longitudinal carbon fiber winding reinforcing layers enables the circumferential bursting pressure of the gas cylinder to be far higher than the working pressure requirement, so that the requirements of spaceflight high-pressure working conditions are met.

Description

Technical Field

[0001] This invention relates to the field of aerospace high-pressure gas cylinder supporting structure and processing technology, specifically a composite gas cylinder support structure and its processing method. Background Technology

[0002] With the rapid development of aerospace technology, the demand for high-pressure gas cylinders in spacecraft is increasing day by day. As an indispensable key component in the aerospace field, high-pressure gas cylinders are widely used in propulsion systems, fluid management systems, life support systems and environmental control systems, pressurizing rocket fuel tanks, providing high-pressure gas sources for satellites, and ensuring the on-orbit safety of astronauts.

[0003] Space missions place extremely stringent performance requirements on high-pressure gas cylinders. These cylinders must possess high strength, lightweight design, corrosion resistance, resistance to extreme temperatures, and environmental adaptability, while also meeting stringent quantitative specifications: operating pressure exceeding 70 MPa, weight not exceeding 2 kg, and volume not less than 2.8 L. Furthermore, to reduce spacecraft launch costs and improve overall operational reliability, the material utilization rate, assembly processability, and production efficiency of high-pressure gas cylinders are also key considerations.

[0004] In existing technologies, aerospace high-pressure gas cylinders mostly use titanium alloys (such as TA2 or TC4) as the inner lining material. The upper and lower shells are electron-beam welded into an ellipsoidal structure, and a composite material reinforcement layer is wrapped around the outside of the lining to improve structural strength. The support frame is made of titanium alloy TC4 and is connected to the gas cylinder by mechanical connection or welding. However, this technical solution has certain technical drawbacks: 1. Traditional metal gas cylinders, designed to meet high strength requirements, often have thick walls. Combined with redundant connection structures between the support and the cylinder body, this results in excessive overall weight, hindering the spacecraft's overall weight reduction needs. 2. The manufacturing process is highly complex: welding and forming processes are demanding, prone to defects such as porosity and delamination, and material utilization is low. 3. Furthermore, the lack of standardized tooling positioning makes it difficult to guarantee the accuracy of support installation. 4. Under high-pressure cyclic loads, fatigue cracks easily appear at the cylinder welds and support connections, leading to decreased sealing performance, excessive leakage, and impacting the spacecraft's on-orbit reliability. 5. The interface and support structure designs are not integrated and optimized, resulting in cumbersome installation and maintenance procedures that fail to meet the rapid assembly requirements of spacecraft components. Summary of the Invention

[0005] The purpose of this invention is to provide a composite gas cylinder support structure and its processing method to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a composite gas cylinder support structure and its processing method, comprising a composite gas cylinder, wherein the composite gas cylinder comprises a titanium alloy TA2 liner, a carbon fiber winding reinforcement layer, a support, a mounting plate, and a carbon fiber winding fixing layer; The bracket is a TC4 titanium alloy integral bracket. The bracket is installed on one side of the mounting plate. The bracket has a titanium alloy TA2 inner liner inside. The outer wall of the titanium alloy TA2 inner liner is wrapped with a carbon fiber winding reinforcement layer. The outer side of the bracket is wrapped with a carbon fiber winding fixing layer. The titanium alloy TA2 liner is formed by electron beam welding of an upper and lower half-shell using an interlocking structure. The outer surfaces of the upper and lower half-shells are ellipsoidal, and the generatrix equations are as follows: The upper and lower shell interfaces are integrally formed with the end caps; the titanium alloy TA2 liner has a cylindrical wall thickness of 0.7mm, an end cap bottom thickness of 2.5mm, an end cap bottom profile height of 41.47mm, and an inner diameter D of the liner. i The diameter is 165.5mm, and it meets the design requirements for a flattened ellipsoidal head: 0.5≤2H / D. i ≤0.7071, H is the height of the base shape; The carbon fiber winding reinforcement layer includes a circumferential winding layer and a helical winding layer, and is prepared by a wet fiber winding molding process. The circumferential winding layer has 16 rings, a single layer thickness of 0.208 mm, and a total thickness of 3.328 mm. The helical winding layer has 6 longitudinal rings, a single layer thickness of 0.202 mm, and a total thickness of 2.424 mm. The total thickness of the carbon fiber winding reinforcement layer is 5.76 mm. The TC4 titanium alloy integral bracket is positioned and fixed at a preset position on the body of the composite gas cylinder by a special tool. The special tool serves both as a gas cylinder winding tool and a bracket positioning tool. The integral bracket is wrapped with a carbon fiber winding fixing layer. The winding thickness of the carbon fiber winding fixing layer is 1 mm, and the fiber weight is 0.035 kg. During winding, the fiber tension is adjusted to make the bracket hold the cylinder body tightly.

[0007] Preferably, the material performance parameters of the titanium alloy TA2 liner meet the following requirements: tensile strength ≥400MPa, specified non-proportional elongation strength R p0.2 ≥275MPa, elongation after fracture The titanium alloy TA2 liner has an outer diameter ≤ Φ168.7mm, a length ≤ 202mm, a weight ≤ 0.7kg, and a volume of 2.835L.

[0008] Preferably, both the carbon fiber winding reinforcement layer and the carbon fiber winding fixing layer are made of CCF1000G high-strength carbon fiber. The design parameters of the CCF1000G high-strength carbon fiber are: tensile strength 5800MPa, elastic modulus 280GPa, elongation at break 2.2%, and linear density 450g / km. The resin content of the carbon fiber winding is 22%-28%, and the tension control accuracy of each yarn during the winding process is 5%.

[0009] Preferably, the TC4 titanium alloy integral bracket undergoes low-magnification inspection and is free of cracks, pores, inclusions, and segregation; it also undergoes 100% ultrasonic testing and meets Class A requirements.

[0010] Preferably, the overall structural parameters of the composite gas cylinder and the TC4 titanium alloy integral bracket meet the following requirements: total weight 1.875 kg, total outer diameter Φ187.5 ± 0.1 mm, total length 202 mm, working pressure 70 MPa, burst pressure ≥ 120 MPa, and helium mass spectrometry leak detection result less than [value missing]. .

[0011] Preferably, the bottom end of the bracket is provided with multiple bends, and the end face of the bend away from the titanium alloy TA2 liner is fitted with a mounting plate. The surface of the bend is provided with through holes that are aligned with the through holes on the surface of the mounting plate. The mounting plate is threadedly connected to the bottle mouth of the titanium alloy TA2 liner. The top end of the bracket is provided with multiple pairs of protrusions, and the surface of the protrusions away from the titanium alloy TA2 liner is provided with grooves for being wound by the carbon fiber winding fixing layer.

[0012] Preferably, the process includes three parts: inner liner molding process, support molding process, and overall cylinder winding and curing process. The specific steps are as follows: S1. Liner molding: 1.1 End Cap Machining: The titanium alloy TA2 bar stock is cut into blanks → annealed → rough turned → stress-relief annealed → precision turned inner arc → precision turned outer arc → precision turned bottle mouth / tail top → alcohol cleaning → finished product inspection to obtain upper and lower shell end caps; 1.2 Inner liner welding: The upper and lower shell components are assembled and formed by electron beam welding. The process is as follows: laser marking → stress relief annealing → performance testing → weld radiographic inspection → volumetric weight testing → helium airtightness test → alcohol cleaning → cleanliness testing → final inspection, to obtain the titanium alloy TA2 inner liner; S2. Support Forming: The TC4 titanium alloy bar material is inspected upon arrival at the factory, then cut, machined, ground, and inspected to produce an integral bracket. The machining process uses multiple small-batch processing to ensure product precision. S3. Overall winding and curing of the gas cylinder: 3.1 After the titanium alloy lining is treated for corrosion protection, the carbon fiber winding reinforcement layer is wound using a wet fiber winding molding process. First, 16 rings of circumferential winding are completed, and then 6 longitudinal spiral windings are completed. During the winding process, the tension is controlled layer by layer by electronic tension, and the resin ratio and dosage are controlled. 3.2 After the carbon fiber winding reinforcement layer is cured, the integral bracket is positioned in the preset position on the bottle body using a special tooling, the carbon fiber winding fixing layer is wound and cured, and the thickness of the fixing layer is controlled to be 1mm. 3.3 After grinding → self-tightening → hydrostatic test → acoustic emission test → airtightness test → helium mass spectrometry leak detection → labeling → cleanliness inspection → finished product testing, the finished composite gas cylinder support structure is obtained.

[0013] Preferably, the tension control of carbon fiber winding in step 3.1 is based on ensuring that the lining does not become unstable during the winding process and does not wrinkle or deform during the gas cylinder release process; the curing process in step 3.2 is a key process, and the furnace temperature process parameters must be strictly controlled.

[0014] Preferably, the finished product testing in step 3.3 must meet the following requirements: overall weight ≤ 2kg, volume ≥ 2.8L, burst pressure ≥ 120MPa, and helium mass spectrometry leak detection result less than [value missing]. After passing the inspection, finished products are sampled for identification tests according to the technical requirements.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: the composite gas cylinder support structure and its processing method have the following advantages over traditional technologies: 1. The integrated support design, combined with the carbon fiber winding fixing layer, replaces the mechanical / welded connection of the traditional titanium alloy support, improving the connection strength and overall rigidity between the support and the gas cylinder. The flat ellipsoidal head design avoids the adverse effects of circumferential compressive stress on the pressure vessel. The precise design of the 16-ring and 6-longitudinal carbon fiber winding reinforcement layer enables the gas cylinder to have a circumferential burst pressure of 127MPa and a longitudinal burst pressure of 126MPa, which is far higher than the working pressure requirement of 70MPa, meeting the high-pressure working conditions of aerospace.

[0016] 2. Both the lining and the support adopt standardized molding processes, and undergo multiple annealing and small-batch processing to eliminate stress and avoid deformation; the carbon fiber winding process is controlled by electronic tension layer by layer (accuracy 5%), and the support positioning adopts special tooling with winding function to ensure positioning accuracy; multiple inspection procedures are set up in the entire process chain (radio inspection, ultrasonic flaw detection, helium air tightness test, helium mass spectrometry leak detection, etc.), and the quality is controlled throughout the entire process from raw materials, semi-finished products to finished products, resulting in high product accuracy and stability.

[0017] 3. Specialized tooling combines cylinder winding and bracket positioning, enabling precise and rapid bracket positioning without additional positioning calibration procedures; the interface and end cap are integrally formed, and the bracket and cylinder are integrally fixed by carbon fiber winding, replacing the traditional cumbersome mechanical connection / welding process. The wet fiber winding process can be automated, greatly improving production efficiency and meeting the rapid assembly requirements of spacecraft components.

[0018] 4. The invention achieves a total weight of 1.875kg, which is lower than the 2kg weight limit of the prior art. The volume of 2.835L meets the requirement of ≥2.8L. The overall structure is compact (outer diameter Φ187.5mm, length 202mm), which is suitable for the limited installation space of spacecraft. The bracket and bottle body are integrated with no additional connecting parts. During installation, they can be directly connected to the system interface. Later maintenance does not require disassembly of the connecting structure, which reduces the difficulty of on-orbit maintenance of spacecraft.

[0019] 5. The titanium alloy TA2 inner liner adopts a thin-wall design (0.7mm), which, combined with the lightweight characteristics of carbon fiber composite materials, greatly improves the material utilization rate and avoids the material waste of traditional metal brackets and connecting structures. The standardized molding process and automated winding process reduce defects caused by manual operation and lower the rework rate in the later stage. At the same time, precise control of resin and carbon fiber usage further controls production costs.

[0020] 6. After welding, the inner lining undergoes weld radiographic inspection and helium leak testing. The finished product undergoes hydrostatic testing, acoustic emission testing, and helium mass spectrometry leak detection (results < Multiple sealing tests ensure that the product has no risk of leakage; the carbon fiber winding fixing layer makes the bracket fit tightly with the bottle body, avoiding fatigue cracks at the connection points under high pressure cyclic loads and improving the reliability of the product in orbit. Attached Figure Description

[0021] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and parts and elements are not necessarily drawn to scale.

[0022] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 for Figure 1 A schematic diagram of the structure after removing the mounting plate; Figure 3 This is a schematic diagram of the connection structure between the tray, the bracket, and the titanium alloy TA2 liner of the present invention; Figure 4 for Figure 3 Schematic diagram of the mid-support structure; Figure 5 for Figure 1 Schematic diagram of the structure of the middle plate; Figure 6 for Figure 2 Front view partial sectional view; Figure 7 A summary diagram of the overall design parameters for the composite gas cylinder support structure.

[0023] In the figure: 1. Titanium alloy TA2 liner, 2. Carbon fiber winding reinforcement layer, 3. Bracket, 31. Fold, 32. Protrusion, 33. Groove, 4. Plate, 5. Carbon fiber winding fixing layer. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Please see Figures 1-7 This invention provides a technical solution comprising a composite gas cylinder, which includes a titanium alloy TA2 liner 1, a carbon fiber winding reinforcement layer 2, a support 3, a mounting plate 4, and a carbon fiber winding fixing layer 5. The support 3 is an integral TC4 titanium alloy support. The support 3 is mounted on one side of the mounting plate 4. The titanium alloy TA2 liner 1 is disposed inside the support 3. The outer wall of the titanium alloy TA2 liner 1 is wound with the carbon fiber winding reinforcement layer 2, and the outer side of the support 3 is wound with the carbon fiber winding fixing layer 5. The titanium alloy TA2 liner is formed by electron beam welding of an upper half shell and a lower half shell using an interlocking structure. The outer surfaces of the upper and lower half shells are ellipsoidal surfaces with generatrices of equation [equation missing]. The upper and lower shell interfaces are integrally formed with the end caps; the titanium alloy TA2 liner has a cylinder wall thickness of 0.7mm, an end cap bottom thickness of 2.5mm, an end cap bottom profile height of 41.47mm, and an inner diameter D of the liner. i The diameter is 165.5mm, and it meets the design requirements for a flattened ellipsoidal head: 0.5≤2H / D. i≤0.7071, H is the base height; the carbon fiber winding reinforcement layer includes a circumferential winding layer and a spiral winding layer, which are prepared by wet fiber winding molding process. The circumferential winding layer has 16 rings, a single layer thickness of 0.208mm, and a total thickness of 3.328mm. The spiral winding layer has 6 longitudinal rings, a single layer thickness of 0.202mm, and a total thickness of 2.424mm. The total thickness of the carbon fiber winding reinforcement layer is 5.76mm. The TC4 titanium alloy integral bracket is positioned and fixed in the preset position of the composite gas cylinder by special tooling. The special tooling has the functions of gas cylinder winding and bracket positioning. The integral bracket is wrapped with a carbon fiber winding fixing layer 5. The winding thickness of the carbon fiber winding fixing layer 5 is 1mm, and the fiber weight is 0.035kg. During winding, the fiber tension is adjusted to make the bracket hold the cylinder body tightly.

[0026] In the specific implementation process, it is worth noting that the axial position deviation of the bracket 3 is controlled within ±0.5mm, and the circumferential coaxiality deviation is controlled within ≤0.05mm. This ensures that the installation position of the bracket 3 fully meets the interface requirements of the system integration. When winding the carbon fiber winding fixing layer 5, the fiber tension is adjusted step by step to make the inner arc surface of the bracket 3 completely fit with the outer arc surface of the cylinder, eliminating the fit gap and making the bracket 3 and the cylinder form an integrated load-bearing structure. This avoids the problem of bracket loosening, abnormal noise or displacement under high pressure cyclic load. The fiber amount and winding tension of the carbon fiber winding fixing layer 5 are matched with the process parameters of the main carbon fiber winding reinforcement layer to ensure the bonding strength between the fixing layer and the main reinforcement layer and avoid interlayer separation defects.

[0027] Furthermore, the material properties of the titanium alloy TA2 liner meet the following requirements: tensile strength. ≥400MPa, specified non-proportional elongation strength R p0.2 ≥275MPa, elongation after fracture The outer diameter of the TA2 titanium alloy liner is ≤168.7mm, the length is ≤202mm, the weight is ≤0.7kg, and the volume is 2.835L.

[0028] In the specific implementation process, it is worth noting that the wall thickness of the inner liner is 0.7mm, which meets the requirements of the technical standards for the outer dimensions, volume, working pressure and burst pressure, as well as the tension control force during the winding of the carbon fiber winding machine. This wall thickness can completely ensure that the inner liner does not experience compression instability during the winding process, and that the inner liner does not wrinkle or deform during the rapid release of gas from the cylinder. The flat ellipsoid design of the inner liner head follows the requirements for the heads of wound pressure vessels, namely 0.5≤2H / Di≤0.7071, which can avoid the problem that the circumferential compressive stress at the end of the standard ellipsoid head after pressure bearing is not suitable for the wound pressure vessel.

[0029] Furthermore, both the carbon fiber winding reinforcement layer 2 and the carbon fiber winding fixing layer 5 are made of CCF1000G high-strength carbon fiber. The design parameters of CCF1000G high-strength carbon fiber are: tensile strength 5800MPa, elastic modulus 280GPa, elongation at break 2.2%, and linear density 450g / km. The resin content of the carbon fiber winding is 22%-28%, and the tension control accuracy of each yarn during the winding process is 5%.

[0030] In the specific implementation process, it is worth noting that the thickness design of this carbon fiber winding reinforcement layer 2 is derived and calculated based on grid theory. The design parameters are: working pressure of gas cylinder 70MPa, burst pressure ≥120MPa, outer diameter of gas cylinder ≤Φ190mm, and resin content 22%~28%. The core design calculation formula is as follows: 1- Formula for calculating the design thickness of carbon fiber circumferential winding layer: The calculated minimum design thickness of the circumferential layer is 3.155 mm, but the actual thickness is ≥3.16 mm. 2-Calculation formula for the design thickness of carbon fiber spiral winding layer: The calculated minimum design thickness of the spiral layer is 2.298 mm, but the actual thickness is ≥2.3 mm. Based on the above calculations, the final design for the winding layup is 16 rings and 6 longitudinals, wherein: The cross-sectional area of ​​carbon fiber is The thickness of a single circumferential winding layer is 0.208mm, and the total thickness of 16 rings is 0.208mm × 16 = 3.328mm, which is greater than the minimum design thickness of 3.16mm. The calculated circumferential burst pressure is 127MPa, which meets the requirement of ≥120MPa. Symbols in the above formula: : Thickness of carbon fiber spiral layer; : Thickness of the carbon fiber circumferential layer; : Gas cylinder burst pressure; : Inner lining burst pressure; : Tensile strength of carbon fiber; : Carbon fiber volume content; : Wrapping angle ( R: Inner liner radius; d: Gas cylinder pole hole diameter; D: Gas cylinder inner liner outer diameter; A: Carbon fiber cross-sectional area; T: Carbon fiber linear density; Carbon fiber density; The thickness of a single layer of spiral winding is 0.202mm. The total thickness of the 6-longitudinal double-sided symmetrical winding is 0.202mm×6×2=2.424mm, which is greater than the minimum design thickness of 2.3mm. The calculated longitudinal burst pressure is 126MPa, which meets the requirement of ≥120MPa. The total thickness of the carbon fiber is 3.328mm + 2.424mm = 5.752mm, and the actual thickness is taken as 5.76mm. The total length of carbon fiber used is 1277m. Based on the linear density and volume content, the carbon fiber usage is calculated to be 0.574kg, and the total weight of the carbon fiber layer is 0.776kg. Considering the difference in adhesive content, the final design weight of the carbon fiber layer is 0.78kg. The batch measured properties of the CCF1000G high-strength carbon fiber used are tensile strength 6190~6470MPa, elastic modulus 295~302GPa, elongation at break 2.16~2.29%, and linear density 445~458g / km. The measured values ​​are all higher than the design values, which can fully guarantee the structural strength redundancy.

[0031] Furthermore, the TC4 titanium alloy integral bracket underwent low-magnification inspection and found no cracks, pores, inclusions, or segregation; it also underwent 100% ultrasonic testing and met the Class A requirements.

[0032] In the specific implementation process, it is particularly important to point out that the raw materials for the TC4 titanium alloy integral bracket must meet the national standards for titanium and titanium alloy rods. Upon arrival at the factory, a full range of standard inspections must be completed: chemical composition retesting to ensure that the content of alloy elements meets the standard requirements; low-magnification microstructure inspection to ensure the absence of metallurgical defects such as cracks, pores, and inclusions, and no component segregation; 100% ultrasonic testing, with the testing level meeting the Class A requirement; and bracket machining using a multi-batch processing method, with the single machining allowance controlled within 0.1mm. This effectively avoids thermal deformation and stress deformation during the machining of titanium alloy materials, ensuring the fit between the inner arc surface of the bracket and the outer arc surface of the bottle, as well as the dimensional and positional tolerances of the bracket installation interface, thus ensuring the subsequent assembly accuracy.

[0033] Furthermore, the overall structural parameters of the composite gas cylinder and the TC4 titanium alloy integral support meet the following requirements: total weight 1.875 kg, total outer diameter Φ187.5 ± 0.1 mm, total length 202 mm, working pressure 70 MPa, burst pressure ≥ 120 MPa, and helium mass spectrometry leak detection result less than [value missing]. .

[0034] Furthermore, the bottom end of the bracket 3 is provided with multiple bends 31. The end face of the bend 31 away from the titanium alloy TA2 liner 1 is attached to the mounting plate 4. The surface of the bend 31 is provided with through holes that are aligned with the through holes on the surface of the mounting plate 4. The mounting plate 4 is threadedly connected to the bottle mouth of the titanium alloy TA2 liner 1. The top end of the bracket 3 is provided with multiple pairs of protrusions 32. The surface of the protrusions 32 away from the titanium alloy TA2 liner 1 is provided with grooves 33 for being wound by the carbon fiber winding fixing layer.

[0035] In the specific implementation process, it is worth noting that the bend angle 31 is a structure integrally bent into the bracket 3, and is set at a preset angle with the main body of the bracket, which can realize the fit between the bottom end of the bracket 3 and the mounting plate 4. The number of bend angles 31 matches the installation points of the mounting plate 4, and generally four are set and evenly distributed around the circumference. The through holes opened on the bend angles 31 are countersunk through holes, and the hole diameter is compatible with the connecting fasteners matched with the aerospace system. The mounting plate 4 is a ring-shaped TC4 titanium alloy structure, and the internal thread opened on its inner wall matches the external thread of the bottle mouth of the titanium alloy TA2 inner liner 1. The tightening torque of the threaded connection is strictly controlled within a preset range to ensure the sealing and tightness of the connection between the mounting plate 4 and the bottle mouth. The mounting plate 4, through the fit with the through hole of the bend angle 31, realizes the double fit between the bottom end of the bracket and the mounting plate 4. The bracket is designed to limit the movement of the support and prevent circumferential rotation and axial displacement on the bottle. The protrusion 32 is also a machined integral structure of the support 3. It is symmetrically distributed in pairs on the top of the support 3. The extension direction of the protrusion 32 is parallel to the axial direction of the bottle. The groove 33 on its outer surface is an arc-shaped annular groove. The groove width is adapted to the width of the fiber bundle of the carbon fiber winding fixing layer 5. The groove depth is 0.3mm-0.5mm. When the carbon fiber winding fixing layer 5 is wound, it can be embedded in the groove 33 to form a mechanical interlocking structure, which prevents the carbon fiber winding fixing layer from slipping or loosening under vibration and impact conditions. At the same time, the groove 33 can increase the contact area between the carbon fiber and the support, improve the bonding strength between the fiber fixing layer and the support 3, and make the connection between the support 3 and the bottle more stable.

[0036] In the specific implementation process, it is worth noting that the overall design parameters of this composite gas cylinder support structure have been fully calculated, and the specific design calculations are summarized as follows: Figure 7 As shown.

[0037] Furthermore, it includes three parts: the inner lining molding process, the support molding process, and the overall cylinder winding and curing process. The specific steps are as follows: S1. Liner molding: 1.1 End Cap Machining: The titanium alloy TA2 bar stock is cut into blanks → annealed → rough turned → stress-relief annealed → precision turned inner arc → precision turned outer arc → precision turned bottle mouth / tail top → alcohol cleaning → finished product inspection to obtain upper and lower shell end caps; 1.2 Inner liner welding: The upper and lower shell components are assembled and formed by electron beam welding. The process is as follows: laser marking → stress relief annealing → performance testing → weld radiographic inspection → volumetric weight testing → helium airtightness test → alcohol cleaning → cleanliness testing → final inspection, to obtain the titanium alloy TA2 inner liner; S2. Support Forming: The TC4 titanium alloy bar material is inspected upon arrival at the factory, then cut, machined, ground, and inspected to produce an integral bracket. The machining process uses multiple small-batch processing to ensure product precision. S3. Overall winding and curing of the gas cylinder: 3.1 After the titanium alloy lining is treated for corrosion protection, the carbon fiber winding reinforcement layer is wound using a wet fiber winding molding process. First, 16 rings of circumferential winding are completed, and then 6 longitudinal spiral windings are completed. During the winding process, the tension is controlled layer by layer by electronic tension, and the resin ratio and dosage are controlled. 3.2 After the carbon fiber winding reinforcement layer is cured, the integral bracket is positioned in the preset position on the bottle body using a special tooling, the carbon fiber winding fixing layer is wound and cured, and the thickness of the fixing layer is controlled to be 1mm. 3.3 After grinding → self-tightening → hydrostatic test → acoustic emission test → airtightness test → helium mass spectrometry leak detection → labeling → cleanliness inspection → finished product testing, the finished composite gas cylinder support structure is obtained.

[0038] In the specific implementation process, it is worth noting that the overall winding and curing of this gas cylinder adopts a wet fiber winding molding process. The complete process route is as follows: titanium alloy inner lining anti-corrosion → carbon fiber winding reinforcement layer winding → first curing → bracket positioning and carbon fiber winding fixing layer winding → second curing → grinding → self-tightening → hydrostatic test → acoustic emission test → airtightness test → helium mass spectrometry leak detection → labeling → cleanliness inspection → finished product inspection. The wet winding process allows the resin to fully impregnate the carbon fiber, effectively improving the bonding force between the fiber and the resin and increasing the fiber strength utilization rate. During the winding process, the direction, number of layers, and winding angle of the carbon fiber are strictly executed according to the design model. The layup sequence of first circumferential winding and then spiral winding can effectively balance the circumferential and axial load-bearing capacity of the gas cylinder and avoid stress concentration during pressure bearing. Both curing processes are special and critical processes in product production, and process parameters need to be verified in advance. During the curing process, core parameters such as furnace temperature and holding time are monitored throughout to ensure that the resin is completely cured and that the carbon fiber layer is free of defects such as delamination, bubbles, and missing glue.

[0039] Furthermore, in step 3.1, the tension control of carbon fiber winding is based on ensuring that the lining does not become unstable during the winding process and does not wrinkle or deform during the gas cylinder release process; in step 3.2, the curing process is a critical process, and the furnace temperature process parameters must be strictly controlled.

[0040] In the specific implementation process, it is worth noting that an electronic tension control system is used during the winding process to achieve closed-loop control of tension layer by layer. The tension control accuracy of each yarn can reach 5%. The tension value can be adjusted step by step according to the number of winding layers. The inner layer winding uses a higher tension, and the outer layer winding uses a gradually decreasing tension, so that the carbon fiber layer forms a pre-stress gradient. This avoids the inner lining from being too tense and becoming unstable due to excessive tension, and also avoids the fiber layer from not being tightly bonded and having insufficient strength due to insufficient tension. At the same time, it can effectively prevent the inner lining from wrinkling and deforming due to the difference in deformation between the inner lining and the carbon fiber layer during the rapid release of gas cylinder. The curing process requires strict control of the furnace temperature uniformity, with the temperature difference in the furnace controlled within ±5℃. At the same time, the heating rate, holding temperature, holding time and cooling rate must be strictly controlled to avoid thermal stress deformation between the carbon fiber layer and the inner lining and the support due to sudden temperature rise and fall, as well as defects such as interlayer separation and resin cracking, ensuring the structural strength and bonding performance of the carbon fiber layer after curing.

[0041] Furthermore, the finished product testing in step 3.3 must meet the following requirements: overall weight ≤ 2kg, volume ≥ 2.8L, burst pressure ≥ 120MPa, and helium mass spectrometry leak detection result less than [value missing]. After passing the inspection, finished products are sampled for identification tests according to the technical requirements.

[0042] In the specific implementation process, it is worth noting that each step of the finished product inspection has clear acceptance criteria. Specifically: the self-tightening process uses a 90MPa hydraulic load for pressure holding, causing slight plastic deformation of the lining and prestressing of the carbon fiber layer, effectively improving the fatigue cycle life of the gas cylinder; the hydrostatic test uses a 126MPa test pressure to verify the pressure resistance of the gas cylinder, and no leakage or significant plastic deformation during the pressure holding process constitutes acceptance; the acoustic emission test is conducted simultaneously with the hydrostatic test, monitoring the defect propagation signals inside the gas cylinder throughout the process, predicting potential failure risks, and ensuring that the product has no hidden internal defects; the airtightness test uses a 70MPa working pressure for initial verification of sealing performance, followed by high-precision leak detection using helium mass spectrometry to ensure a leakage rate of less than [missing value]. After all the finished products pass the inspection, a certain proportion of the finished products must be randomly selected for type qualification tests according to the technical requirements. The qualification tests include fatigue cycle tests, extreme burst tests, high and low temperature environment adaptability tests, vibration and shock tests, etc., to comprehensively verify the full performance of the product under aerospace conditions and ensure that the product meets the usage requirements of aerospace missions.

[0043] Working principle: Pressure bearing principle: The pressure bearing capacity of this structure during operation is achieved collaboratively by the titanium alloy TA2 liner and the carbon fiber wound reinforcement layer. The 70MPa working pressure inside the gas cylinder first acts on the inner wall of the titanium alloy TA2 liner. As an airtight inner layer, the liner's 0.7mm cylinder wall thickness can withstand the compressive load during the winding process and the negative pressure load during the venting process, preventing instability and wrinkling deformation. The flattened ellipsoidal head structure of the upper and lower shells conforms to 0.5≤2H / D. i The design criterion of ≤0.7071 for spiral wound pressure vessels can disperse the end stress under pressure and avoid the mismatch of circumferential compressive stress of standard ellipsoidal heads. The internal pressure load is transferred to the carbon fiber spiral wound reinforcement layer through the inner lining. The 16-ring circumferential spiral wound layer bears the main circumferential tensile stress, and the 6-longitudinal spiral wound layer bears the axial tensile stress. The two work together to ensure that the burst pressure of the gas cylinder is not less than 120MPa, achieving lightweight design while meeting the high pressure bearing requirements.

[0044] Bracket fixing principle: The TC4 titanium alloy integral bracket achieves fixation and load-bearing through a positioning and locking mechanism and an integrated load-bearing system. Before operation, a special tooling that combines cylinder winding and bracket positioning functions precisely positions the bracket at the preset position on the cylinder body, with axial position deviation controlled within ±0.5mm and circumferential coaxiality deviation controlled within ≤0.05mm, ensuring matching accuracy with the system installation interface. A 1mm thick carbon fiber winding fixing layer is wound around the outside of the bracket, and the fiber tension is adjusted step by step during the winding process to ensure that the inner arc surface of the bracket and the outer arc surface of the cylinder are completely fitted to eliminate the gap. The carbon fiber winding fixing layer and the main carbon fiber winding reinforcement layer have matching process parameters and excellent bonding strength, which can lock the bracket and the cylinder body into an integrated structure. When the cylinder is in operation, the bracket can stably transmit the installation load and vibration load, avoiding problems such as bracket loosening, abnormal noise or displacement under high-pressure cyclic conditions, and ensuring long-term support stability.

[0045] Molding process principle: The molding process of this structure is based on the core principles of performance assurance and precision control. The titanium alloy TA2 liner is formed by electron beam welding of the upper and lower half-shells through an interlocking structure. The integrated design of the interface and end cap reduces the number of welds and minimizes the impact of welding defects on structural strength and sealing. Both the carbon fiber winding reinforcement layer and the carbon fiber winding fixing layer adopt a wet fiber winding molding process. Through an electronic tension system, layer-by-layer tension closed-loop control is achieved, with a tension control accuracy of 5% for each yarn. The tension value can be adjusted according to the gradient of the number of winding layers to form a prestress gradient, which ensures a tight fit between the carbon fiber and the liner and support, while avoiding excessive tension that could lead to liner compression instability. The staged curing process ensures that the resin completely impregnates the carbon fiber. During the curing process, strict control of furnace temperature uniformity is maintained to avoid defects such as delamination, bubbles, and insufficient glue, maximizing the tensile strength of the carbon fiber and achieving dual control over structural molding precision and mechanical properties.

[0046] Reliable sealing principle: The sealing performance of this structure is achieved through a hierarchical, end-to-end control principle. The titanium alloy TA2 liner serves as the core airtight layer. After the upper and lower shells are welded together, they undergo dual verification through weld X-ray inspection and helium mass spectrometry testing to eliminate the risk of weld leakage. After the liner is fully formed, a full-cavity helium mass spectrometry leak test is performed again to ensure that the basic sealing performance meets requirements. The carbon fiber winding reinforcement layer, after curing, forms a complete external protective layer that isolates external corrosive media, preventing corrosion leakage of the titanium alloy liner. It also constrains the deformation of the liner, preventing fatigue cracking and sealing failure under high-pressure cycling. In the finished product stage, high-pressure airtightness testing and high-precision helium mass spectrometry leak testing are performed sequentially to ensure that the leakage rate of the product under working pressure is less than [a certain value]. It meets the long-term sealing requirements of aerospace high-pressure conditions.

[0047] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A composite gas cylinder support structure, comprising a composite gas cylinder, characterized in that: The composite gas cylinder includes a titanium alloy TA2 liner (1), a carbon fiber winding reinforcement layer (2), a bracket (3), a mounting plate (4), and a carbon fiber winding fixing layer (5). The bracket (3) is a TC4 titanium alloy integral bracket. The bracket (3) is installed on one side of the mounting plate (4). The bracket (3) is provided with a titanium alloy TA2 inner liner (1). The outer wall of the titanium alloy TA2 inner liner (1) is wrapped with a carbon fiber winding reinforcement layer (2). The outer side of the bracket (3) is wrapped with a carbon fiber winding fixing layer (5). The titanium alloy TA2 liner is formed by electron beam welding of an upper and lower half-shell using an interlocking structure. The outer surfaces of the upper and lower half-shells are ellipsoidal, and the generatrix equations are as follows: The upper and lower shell interfaces are integrally formed with the end caps; the titanium alloy TA2 liner has a cylindrical wall thickness of 0.7mm, an end cap bottom thickness of 2.5mm, an end cap bottom profile height of 41.47mm, and an inner diameter D of the liner. i The diameter is 165.5mm, and it meets the design requirements for a flattened ellipsoidal head: 0.5≤2H / D. i ≤0.7071, H is the height of the base shape; The carbon fiber winding reinforcement layer (2) includes a circumferential winding layer and a helical winding layer, and is prepared by a wet fiber winding molding process. The circumferential winding layer has 16 rings, a single layer thickness of 0.208 mm, and a total thickness of 3.328 mm. The helical winding layer has 6 longitudinal rings, a single layer thickness of 0.202 mm, and a total thickness of 2.424 mm. The total thickness of the carbon fiber winding reinforcement layer is 5.76 mm. The TC4 titanium alloy integral bracket is positioned and fixed at a preset position on the body of the composite gas cylinder by a special tool. The special tool has both the functions of cylinder winding and bracket positioning. The integral bracket is wrapped with a carbon fiber winding fixing layer (5). The winding thickness of the carbon fiber winding fixing layer (5) is 1mm and the fiber weight is 0.035kg. During winding, the fiber tension is adjusted to make the bracket hold the cylinder body tightly.

2. The composite gas cylinder support structure according to claim 1, characterized in that: The material properties of the titanium alloy TA2 liner meet the following requirements: tensile strength. ≥400MPa, specified non-proportional elongation strength R p0.2 ≥275MPa, elongation after fracture The titanium alloy TA2 liner has an outer diameter ≤ Φ168.7mm, a length ≤ 202mm, a weight ≤ 0.7kg, and a volume of 2.835L.

3. The composite gas cylinder support structure according to claim 1, characterized in that: Both the carbon fiber winding reinforcement layer (2) and the carbon fiber winding fixing layer (5) are made of CCF1000G high-strength carbon fiber. The design parameters of the CCF1000G high-strength carbon fiber are: tensile strength 5800MPa, elastic modulus 280GPa, elongation at break 2.2%, and linear density 450g / km. The resin content of the carbon fiber winding is 22%-28%, and the tension control accuracy of each yarn during the winding process is 5%.

4. The composite gas cylinder support structure according to claim 1, characterized in that: The TC4 titanium alloy integral bracket was inspected at low magnification and found to be free of cracks, pores, inclusions, and segregation; it underwent 100% ultrasonic testing and met the Class A requirements.

5. The composite gas cylinder support structure according to claim 1, characterized in that: The overall structural parameters of the composite gas cylinder and the TC4 titanium alloy integral bracket meet the following requirements: total weight 1.875 kg, total outer diameter Φ187.5 ± 0.1 mm, total length 202 mm, working pressure 70 MPa, burst pressure ≥ 120 MPa, and helium mass spectrometry leak detection result less than [value missing]. .

6. The composite gas cylinder support structure according to claim 1, characterized in that: The bottom end of the bracket (3) is provided with multiple bends (31). The end face of the bend (31) away from the titanium alloy TA2 liner (1) is fitted with a plate (4). The surface of the bend (31) is provided with a through hole that is aligned with the through hole on the surface of the plate (4). The plate (4) is threadedly connected to the bottle mouth of the titanium alloy TA2 liner (1). The top end of the bracket (3) is provided with multiple pairs of protrusions (32). The surface of the protrusions (32) away from the titanium alloy TA2 liner (1) is provided with a groove (33) for being wound by the carbon fiber winding fixing layer.

7. A method for processing a composite gas cylinder support structure according to any one of claims 1-6, characterized in that: It includes three parts: the inner lining molding process, the support molding process, and the overall cylinder winding and curing process. The specific steps are as follows: S1. Liner molding: 1.1 End Cap Machining: The titanium alloy TA2 bar stock is cut into blanks → annealed → rough turned → stress-relief annealed → precision turned inner arc → precision turned outer arc → precision turned bottle mouth / tail top → alcohol cleaning → finished product inspection to obtain upper and lower shell end caps; 1.2 Inner liner welding: The upper and lower shell components are assembled and formed by electron beam welding. The process is as follows: laser marking → stress relief annealing → performance testing → weld radiographic inspection → volumetric weight testing → helium airtightness test → alcohol cleaning → cleanliness testing → final inspection, to obtain the titanium alloy TA2 inner liner; S2. Support Forming: The TC4 titanium alloy bar material is inspected upon arrival at the factory, then cut, machined, ground, and inspected to produce an integral bracket. The machining process uses multiple small-batch processing to ensure product precision. S3. Overall winding and curing of the gas cylinder: 3.1 After the titanium alloy lining is treated for corrosion protection, the carbon fiber winding reinforcement layer is wound using a wet fiber winding molding process. First, 16 rings of circumferential winding are completed, and then 6 longitudinal spiral windings are completed. During the winding process, the tension is controlled layer by layer by electronic tension, and the resin ratio and dosage are controlled. 3.2 After the carbon fiber winding reinforcement layer is cured, the integral bracket is positioned in the preset position on the bottle body using a special tooling, the carbon fiber winding fixing layer is wound and cured, and the thickness of the fixing layer is controlled to be 1mm. 3.3 After grinding → self-tightening → hydrostatic test → acoustic emission test → airtightness test → helium mass spectrometry leak detection → labeling → cleanliness inspection → finished product testing, the finished composite gas cylinder support structure is obtained.

8. The processing method of a composite gas cylinder support structure according to claim 7, characterized in that: In step 3.1, the tension control of carbon fiber winding is based on ensuring that the lining does not become unstable during the winding process and does not wrinkle or deform during the gas cylinder release process; in step 3.2, the curing process is a critical process and the furnace temperature process parameters must be strictly controlled.

9. The processing method of a composite gas cylinder support structure according to claim 7, characterized in that: The finished product testing in step 3.3 must meet the following requirements: overall weight ≤ 2kg, volume ≥ 2.8L, burst pressure ≥ 120MPa, and helium mass spectrometry leak detection result less than [value missing]. After passing the inspection, finished products are sampled for identification tests according to the technical requirements.

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