Large-diameter ultra-high-pressure titanium alloy liner winding gas cylinder and manufacturing method

Abstract

The application provides a large-diameter super-high-pressure titanium alloy inner container winding gas cylinder and a manufacturing method. The gas cylinder comprises a front joint, a front head, a rear head and a rear joint which are sequentially welded. The front head and the rear head are both ellipsoidal. The ratio of the outer diameter D of the gas cylinder to the length L1 is 0.9-1.1. A cylinder linear section is arranged at the middle part of the gas cylinder. The ratio of the outer diameter D of the gas cylinder to the length L2 of the cylinder linear section is 3.5-5.5. The welding structure can reduce the stress concentration phenomenon caused by welding, increase the fatigue life of the gas cylinder, solve the processing problem caused by the sudden change of the thickness of the inner container of the gas cylinder, ensure the internal quality of the gas cylinder, effectively coordinate the stress distribution of each winding layer by using the innovative winding process method and the layering scheme, ensure the bearing capacity of the large-diameter super-high-pressure gas cylinder, and shorten the winding processing period and improve the processing efficiency.

Description

Technical Field

[0001] This invention relates to the technical field of titanium alloy product processing and composite material winding processing, specifically to a large-diameter ultra-high pressure titanium alloy inner liner winding gas cylinder and its manufacturing method. Background Technology

[0002] Currently, the main material used for the inner liner of high-pressure carbon fiber wound gas cylinders is 6061 aluminum alloy. However, aluminum alloy has a low melting point, high chemical reactivity, and is easily oxidized at high temperatures. Furthermore, aluminum alloy is difficult to weld, and the weld seam is prone to porosity. Additionally, the coefficient of linear expansion of aluminum alloy is approximately twice that of steel, making the aluminum alloy weld seam more susceptible to large cracks. Therefore, aluminum alloy inner liners are generally produced by spin forming. However, for wound gas cylinders with special shapes, the spin forming process is difficult and prone to causing overheating.

[0003] Using a stainless steel inner liner would result in an excessively heavy overall cylinder, contradicting the goal of weight reduction achieved through carbon fiber. Therefore, according to GJB9383-2018 "Specification for Carbon Fiber Composite Material Cylinders for Aerospace Use", TA1 titanium alloy can be used as the inner liner material for the wound cylinder, combining the advantages of both aluminum alloy and stainless steel.

[0004] Meanwhile, under ultra-high pressure, the larger the diameter of the gas cylinder, the thicker the required winding layer, which will lead to a decrease in various winding process parameters and an increase in the overall difficulty of the winding process. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a large-diameter, ultra-high pressure titanium alloy inner liner wound gas cylinder and its manufacturing method.

[0006] To solve the above-mentioned technical problems, in a first aspect, the present invention provides a large-diameter ultra-high pressure titanium alloy inner liner wound gas cylinder, the gas cylinder comprising a front joint, a front end cap, a rear end cap, and a rear joint welded in sequence, the front end cap and the rear end cap being both ellipsoidal, the ratio of the outer diameter D of the gas cylinder to its length L1 being 0.9 to 1.1, a straight section of the cylinder being provided in the middle, the ratio of the outer diameter D of the gas cylinder to the length L2 of the straight section of the cylinder being 3.5 to 5.5.

[0007] Furthermore, the front connector includes a cylindrical nozzle body, one end of which is provided with an outer edge for welding to the front end cap. The outer edge is perpendicular to the nozzle body, and the nozzle body and the outer edge are connected by an arc transition. The radius of the arc is R2 = 7~12mm. The nozzle body includes a constant diameter section with a fixed outer diameter and a variable diameter section with a linearly changing outer diameter. The variable diameter section of the nozzle body is disposed between the constant diameter section of the nozzle body and the arc. The diameter of the variable diameter section of the nozzle body gradually decreases from the constant diameter section of the nozzle body to the arc. The included angle α3 between the variable diameter section of the nozzle body and the constant diameter section of the nozzle body is 7.5°~12.5°.

[0008] Furthermore, a welding transition section is provided at the end of the outer edge. The front joint is welded to the front end cap through the welding transition section. The outer wall of the welding transition section is flush with the outer wall of the front end cap. The thickness at the connection between the welding transition section and the outer edge is t1, and the thickness at the weld between the welding transition section and the front end cap is t2, where t2 is the first welding depth. The thickness of the welding transition section changes linearly from one end to the other, so that the inner wall of the welding transition section forms an inclined plane with an angle of α1. The relationships between t1, t2, and α1 satisfy...

[0009] Furthermore, the welding joint between the front end cap and the rear end cap is located on a straight section of the cylinder. One end of the front end cap is sequentially provided with a connecting transition section and a thickened section. The outer wall of the thickened section is flush with the outer wall of the rear end cap. One end of the thickened section is welded to the rear end cap and provided with a locking bottom. The locking bottom is located on one side of the inner wall of the rear end cap and fits against the rear end cap. The length of the locking bottom L4 = 1~3mm, and the end of the locking bottom is provided with a rounded corner with a radius R1 = 0.5~1mm. The distance between the locking bottom and the outer wall of the thickened section is the second welding depth t3. The ratio between the length L5 of the thickened section and the second welding depth t3 is 3~5. The total length L6 of the connecting transition section and the thickened section is greater than L5 + 2t3. The thickness of the connecting transition section changes linearly, and its change angle α2 = 15°~45°.

[0010] Secondly, the present invention provides a method for manufacturing a large-diameter ultra-high pressure titanium alloy inner liner wound gas cylinder, comprising:

[0011] S1. Based on the working medium pressure and temperature, calculate the inner liner volume required to meet the working medium mass, determine the outer diameter of the inner liner and the length of the straight section of the inner liner cylinder; use finite element analysis to perform strength analysis on the inner liner and determine the welded structure dimensions.

[0012] S2. Based on the outer diameter of the inner liner, the burst pressure, and the spiral angle of the outer winding layer of the inner liner, calculate the thickness of the circumferential winding layer and the thickness of the spiral winding layer, and calculate the number of layers of the circumferential winding layer and the number of layers of the spiral winding layer.

[0013] S3. Establish a finite element analysis model of the gas cylinder, analyze the damage mode of the gas cylinder under burst pressure, and obtain the optimal layup mode of the winding layer, as well as the final number of layers of the circumferential winding layer and the final number of layers of the helical winding layer.

[0014] S4. Perform gas cylinder processing.

[0015] Further, step S1 includes:

[0016] According to the Peng-Robinson equation of state, p = RT / (vb) - ac / (v 2 +2bv-b 2Calculate the specific volume v of the working fluid, where a = 0.45724R. 2 T c 2 / p c b = 0.0778RT c / p c , f(w)=0.376464+1.84226w-0.26992w 2 T r =T / T c ;

[0017] In the formula: p is the working fluid pressure, R is the gas constant, T is the working fluid temperature, v is the specific volume of the working fluid, and T c The critical temperature is the highest temperature at which a gas transforms into a liquid. c T is the critical pressure, which is the minimum pressure required for a gas to liquefy at the critical temperature. w is the eccentricity factor, which reflects the shape and polarity of the molecules, determined by the inherent properties of the gas molecules themselves. It can be obtained by consulting relevant chemical parameter tables and conducting experiments. r For comparison temperature;

[0018] Calculate the required inner tank volume based on the specific volume v and the mass of the working fluid.

[0019] Furthermore, in step S1, the weld structure dimensions between the front joint and the front end cap, and between the rear end cap and the rear joint, must meet the following requirements: Where t1 is the thickness at the connection between the welding transition section and the outer edge, t2 is the first welding depth, L3 is the length of the welding transition section, and α is the inclination angle of the inner wall of the welding transition section;

[0020] The welding structure dimensions of the front and rear end caps must meet the following requirements: the lock bottom extension length L4 = 1~3mm, the radius of the rounded corner at the end of the lock bottom R1 = 0.5~1mm, the ratio between the length of the thickened section L5 and the second welding depth t3 = 3~5, the total length of the connecting transition section and the thickened section L6 > L5 + 2t3, and the inclination angle of the inner wall of the connecting transition section α2 = 15°~45°.

[0021] Further, step S2 includes: calculating the thickness of the helical winding layer and the circumferential winding layer using the following formula:

[0022] In the formula, t α t represents the thickness of the spiral winding layer. θ Where R is the thickness of the circumferential winding layer, R is the radius of the inner liner, and P is the thickness of the circumferential winding layer. b Where σ is the blast pressure, α is the helix angle, and [σ] is the blast pressure. fb [ ] represents the allowable fiber strength, k represents the fiber efficiency, k α This is the stress balance coefficient;

[0023] Calculate the number of layers in the circumferential winding layer and the number of layers in the helical winding layer based on the thickness of the circumferential winding layer and the thickness of the helical winding layer.

[0024] Further, step S3 includes:

[0025] S31. Establish a finite element analysis model of the gas cylinder based on the preset layup pattern;

[0026] S32. Analyze the damage mode of the gas cylinder under the burst pressure, determine whether there is a damage location in the winding layer. If there is, extract the stress distribution of each winding layer at the damage location, and determine whether the damage location is in the straight section of the cylinder. If so, proceed to step S33; otherwise, proceed to step S35.

[0027] S33. Determine whether the average stress of the winding layer at the failure location exceeds the fiber strength, or whether the number of times step S34 is executed exceeds n. If so, increase the number of layers of the circumferential winding layer and execute step S32; otherwise, execute step S34.

[0028] S34. While maintaining the characteristics of cyclic layup, adjust the layup pattern and execute step S32;

[0029] S35. Determine whether the average stress of the winding layer at the failure location exceeds the fiber strength, or whether the number of times step S36 is executed exceeds n. If so, increase the number of spiral winding layers and execute step S32; otherwise, execute step S36.

[0030] S36. While maintaining the characteristics of cyclic layup, adjust the layup pattern and execute step S32.

[0031] Further, step S4 includes:

[0032] S41. Heat-treat titanium alloy bars and process them into front and rear joints; inspect the surface defects of the front and rear joints; heat-treat titanium alloy plates and process them into front and rear end caps.

[0033] S42. Pickling is used to treat the surface of the front joint, front end cap, rear end cap, and rear joint. Electron beam welding is used to weld the front joint and front end cap, and the rear joint and rear end cap. After welding, the weld excess height on the inner and outer surfaces is ground off. Finally, the front end cap and rear end cap are welded to complete the cylinder assembly. The weld excess height on the outer surface is ground off, and X-ray inspection is used to check the weld quality.

[0034] S43. Sandblast the outer surface of the inner liner that needs to be wrapped, and apply adhesive to the outer surface of the inner liner.

[0035] S44. Calculate the initial tension F0 of the winding layer using a tension reduction system of decreasing F for every m winding layer. Wind the inner liner with the initial tension F0. During the winding process, pressurized gas is injected into the inner liner to counteract the tension of the winding layer.

[0036] S45. When the thickness of the winding layer reaches 5mm, perform the first pre-curing. After the winding is completed, perform the final curing.

[0037] The beneficial effects of this invention are as follows:

[0038] 1. The front and rear connectors used in this invention can increase the thickness of the winding layer at the nozzle of the gas cylinder, solve the problem of uneven thickness transition of large-diameter nozzles and easy damage to the nozzles under pressure, and effectively prevent the problem of stripping.

[0039] 2. The welding structure adopted in this invention can reduce stress concentration caused by welding, increase the fatigue life of the gas cylinder, solve the processing problems caused by sudden changes in the thickness of the gas cylinder liner, and ensure the internal quality of the gas cylinder.

[0040] 3. This invention adopts an innovative winding process and layup scheme, which can effectively coordinate the stress distribution of each winding layer, ensuring the load-bearing capacity of large-diameter ultra-high pressure gas cylinders. On this basis, the winding process has a short cycle and high processing efficiency.

[0041] 4. This invention proposes a short and thick gas cylinder, which differs from ordinary gas cylinders. It is between conventional gas cylinders and spherical gas cylinders. The ratio of the outer diameter D of the gas cylinder to the length L1 is in the range of 0.9 to 1.1, and the ratio of the outer diameter D of the gas cylinder to the length L2 of the straight section of the cylinder is in the range of 3.5 to 5.5. By controlling the size within this range, it can be ensured that the stress concentration areas of the front and rear end caps will not affect each other, thereby improving the pressure bearing capacity of the gas cylinder. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the structure of the gas cylinder of the present invention;

[0043] Figure 2 for Figure 1 Enlarged view of point A in the middle;

[0044] Figure 3 for Figure 1 Enlarged view at point B in the middle;

[0045] Figure 4 This is a schematic diagram of the front connector of the present invention;

[0046] Figure 5 This is a flowchart illustrating the search and iteration process for the optimal winding scheme of this invention.

[0047] Figure reference numerals: 1. Front connector; 2. Front end cap; 3. Rear end cap; 4. Rear connector; 5. Nozzle body; 6. Outer edge; 7. Welding transition section; 8. Straight section of cylinder; 9. Connecting transition section; 10. Thickened section; 11. Lock bottom. Detailed Implementation

[0048] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0049] For a certain type of fully wound gas cylinder, with a required working pressure of not less than 70MPa, a helium gas loading mass of not less than 5kg, and an inner liner length L1 = 510mm, the specific design and processing method of this gas cylinder is as follows:

[0050] S1, such as Figure 1 As shown, the gas cylinder includes a front connector 1, a front end cap 2, a rear end cap 3, and a rear connector 4 welded in sequence. Both the front end cap 2 and the rear end cap 3 are ellipsoidal. The front connector 1 is a cylindrical structure with open ends, while the rear connector 4 is a solid cylindrical structure. Helium can be injected into the gas cylinder from the front connector 1.

[0051] The specific volume v of the working fluid is calculated based on the Peng-Robinson equation of state. Based on the calculated specific volume v and the working fluid mass of 5 kg, the volume of the inner liner needs to be no less than 65 L.

[0052] The ratio of the outer diameter D of the gas cylinder to its length L1 needs to be within the range of 0.9 to 1.1. Figure 1 As shown, a straight section 8 of the cylinder is provided in the middle of the gas cylinder. The cross-section of the straight section 8 is straight. The ratio of the outer diameter D of the gas cylinder to the length L2 of the straight section 8 needs to be in the range of 3.5 to 5.5. Based on the requirement that the volume should not be less than 65L and the inner liner length L1 = 510mm, the outer diameter D of the inner liner can be calculated to be 520mm, and the length L2 of the straight section 8 of the inner liner to be 103mm.

[0053] A finite element model was established based on the dimensions of the inner liner. Strength analysis of the inner liner was performed using finite element software to determine the dimensions of the welded structure.

[0054] like Figure 2As shown, the front connector 1 includes a nozzle body 5 and an outer edge 6. The nozzle body 5 is a cylindrical structure open at both ends. The outer edge 6 is annularly located at the right end of the nozzle body 5 and is arranged perpendicular to the nozzle body 5. A welding transition section 7 is integrally formed at the end of the outer edge 6. The front connector 1 is welded to the front end cap 2 through the welding transition section 7. The outer wall of the welding transition section 7 is flush with the outer wall of the front end cap 2. The thickness at the connection between the welding transition section 7 and the outer edge 6 is t1, and the thickness at the weld between the welding transition section 7 and the front end cap 2 is t2. t2 is the first welding depth. The thickness of the welding transition section 7 changes linearly from one end to the other, so that the inner wall of the welding transition section 7 forms an inclined plane with an angle of α1. The relationships between t1, t2, and α1 satisfy...

[0055] like Figure 3 As shown, the welding joint between the front end cap 2 and the rear end cap 3 is located on the straight section 8 of the cylinder. The right end of the front end cap 2 is provided with a connecting transition section 9 and a thickened section 10 in sequence. The length of the connecting transition section 9 is L3. The outer wall of the thickened section 10 is flush with the outer wall of the rear end cap 3. One end of the thickened section 10 is welded to the rear end cap 3 and a locking bottom 11 is provided. The locking bottom 11 is located on one side of the inner wall of the rear end cap 3 and fits against the rear end cap 3. The length of the locking bottom 11 is L4 = 1~3mm. The end of the locking bottom 11 is provided with a rounded corner with a radius R1 = 0.5~1mm. The distance between the locking bottom 11 and the outer wall of the thickened section 10 is the second welding depth t3. The ratio between the length L5 of the thickened section 10 and the second welding depth t3 is 3~5. The total length L6 of the connecting transition section 9 and the thickened section 10 is L5+2t3. The thickness of the connecting transition section 9 changes linearly, and its change angle α2 = 15°~45°.

[0056] The above welding structure values ​​are all obtained based on welding experience parameters and the parameters given in GB150 for bottom-lock welding. Based on the welding strength simulation results, the following values ​​are obtained for front joint 1 and front end cap 2: t1 = 4mm, t2 = 3mm, L3 = 3mm, α = 104°. The structural dimensions of rear joint 4 are the same as those of front joint 1. For front end cap 2 and rear end cap 3: L4 = 3mm, L5 = 13mm, L6 = 19mm, R1 = 0.7mm, t3 = 3mm, α2 = 30°.

[0057] like Figure 4As shown, for a thick winding layer caused by large diameter and high pressure, the wound fibers tend to slide down the end cap due to insufficient friction, accumulating in a clump at the joint. To reduce this phenomenon, the joint structure was optimized: the nozzle 5 and the outer edge 6 are connected by an arc transition, with a radius R2 = 7-12 mm. The nozzle 5 includes a constant diameter section with a fixed outer diameter and a variable diameter section with a linearly changing outer diameter. The variable diameter section of the nozzle 5 is located between the constant diameter section and the arc. The diameter of the variable diameter section of the nozzle 5 gradually decreases from the constant diameter section to the arc. The included angle α3 between the variable diameter section and the constant diameter section of the nozzle 5 is 7.5°-12.5°. In this embodiment, α3 = 10°, and R2 = 10 mm.

[0058] S2. Calculate the thickness of the helical winding layer and the circumferential winding layer using the following formulas:

[0059]

[0060] In the formula, t α t represents the thickness of the spiral winding layer. θ Where R is the thickness of the circumferential winding layer, R is the radius of the inner liner, and P is the thickness of the circumferential winding layer. b Where σ is the blast pressure, α is the helix angle, and [σ] is the blast pressure. fb [ ] represents the allowable fiber strength, k represents the fiber efficiency, k α This is the stress balance coefficient;

[0061] Calculate t θ =9.6mm, t α =6.7mm. Based on the thickness of the circumferential winding layer and the thickness of the spiral winding layer, the number of layers of the circumferential winding layer is calculated to be 42 and the number of layers of the spiral winding layer is 40.

[0062] S3. Carbon fiber winding layer layup design and strength calculation.

[0063] S31. Based on the preset layup pattern, establish a finite element analysis model of the gas cylinder. The preset layup pattern is a three-ring two-spiral layup method, that is, repeatedly winding in a circumferential winding three times and a spiral winding two times. The remaining 12 spiral winding layers are temporarily laid on the outermost side of the inner liner.

[0064] S32. Analyze the damage mode of the gas cylinder under the burst pressure, determine whether there is a damage location in the winding layer. If there is, extract the stress distribution of each winding layer at the damage location, and determine whether the damage location is located in the straight segment 8 of the cylinder. If so, proceed to step S33; otherwise, proceed to step S35.

[0065] S33. Determine whether the average stress of the winding layer at the failure location exceeds the fiber strength, or whether step S34 has been executed more than three times. If so, add one more circumferential winding layer and execute step S32; otherwise, execute step S34.

[0066] S34. While maintaining the characteristics of cyclic layup, adjust the layup pattern and execute step S32. The stress of the gas cylinder generally presents as tight inside and loose outside. For example, in the straight section 8 of the cylinder, the main load-bearing circumferential winding layer should be adjusted to the inner layer of the winding layer, and the non-load-bearing spiral winding layer should be adjusted to the outer layer of the winding layer.

[0067] S35. Determine whether the average stress of the winding layer at the failure location exceeds the fiber strength, or whether step S36 has been executed more than three times. If so, add one more spiral winding layer and execute step S32; otherwise, execute step S36.

[0068] S36. While maintaining the characteristics of cyclic layup, adjust the layup pattern and execute step S32.

[0069] In this embodiment, the gas cylinder has a special shape, with the straight section 8 of the cylinder body accounting for only 20% of the cylinder length. The stress distribution in the straight section 8 differs from that of conventional gas cylinders, and is significantly affected by the end cap. The stress in each layer of the spiral winding cannot be uniformly distributed, resulting in a noticeable tight inner and loose outer spiral winding. Repeated iterations are needed to find the optimal layup scheme. See the details of the above steps below. Figure 5 Through the above iterative cycle, the optimal layup pattern, the number of circumferential winding layers, and the number of helical winding layers can be found. In this embodiment, the optimal layup pattern is a two-ring, two-helix layup, and the optimal number of circumferential winding layers and the optimal number of helical winding layers are 44 and 42, respectively.

[0070] When the above iterative method fails to meet the requirements of layup pattern optimization, it quickly jumps out and directly reduces the stress level of the winding layer by increasing the thickness of the winding layer. At the same time, it does not give up the layup pattern optimization, and takes into account the smoothness of both paths, which has the characteristics of rapid iteration.

[0071] S4, Inner liner molding and carbon fiber winding molding and curing.

[0072] S41. Select TA1 titanium alloy bars that meet GB / T2965. After ultrasonic testing, cut titanium bars with dimensions of Φ160×65mm for heat treatment to eliminate possible residual stress and improve mechanical properties. After heat treatment, machine the titanium alloy bars and inspect the surface defects of front joint 1 and rear joint 4 using non-destructive testing methods.

[0073] According to GB / T3621, the length, width and wall thickness of the titanium alloy plate are selected. The titanium plate is hot stamped at 550-700℃, and the machining allowance is 0.5mm-1.2mm. The preliminarily formed head is machined to remove excess size to achieve the final size state. The surface defects of the front head 2 and the rear head 3 are detected by non-destructive testing.

[0074] S42. Before welding, conduct mechanical property tests on the welding process test plate to confirm that the welding process can meet the welding strength requirements. Use pickling to surface-treat the front and rear end caps 3 and the front and rear nozzles to remove the oxide film. Align the parts using a welding mold, and use electron beam welding to weld the front nozzle and front end cap 2, and the rear nozzle and rear end cap 3. After welding, grind the excess weld height on the inner and outer surfaces. Finally, weld the front end cap 2 and rear end cap 3 to complete the cylinder assembly. Grind the excess weld height on the outer surface of the cylinder to below 2mm to prepare for subsequent winding. After welding, use X-ray inspection to check the weld quality according to GJB1187A. After the inner liner is welded, conduct a hydrostatic strength test to verify the overall welding strength of the inner liner.

[0075] S43. Sandblast the outer surface of the inner liner that needs to be wrapped, and apply adhesive to the outer surface of the inner liner.

[0076] S44. Using a tension reduction system of decreasing by 1N for every three winding layers, calculate the initial tension F0 of the winding layer to be 55N. Wrap the inner liner with an initial tension of 55N. During the winding process, pressurized gas is injected into the inner liner to counteract the tension of the winding layers, so that the inner liner has an internal pressure of 0.8MPa.

[0077] Based on the radii of the front joint 1 and the rear joint 4, as well as the radius of the straight section 8 of the cylinder, the starting winding angle of the geodesic winding is 4.96°. The slip coefficient of the titanium alloy inner liner is measured, and the stable winding angle range is further determined to be ±0.3°.

[0078] S45. During the winding process, when the winding layer thickness reaches 5mm, a pre-curing is performed. The pre-curing regime is room temperature → 100℃±5℃ / 4h → 130℃±7℃ / 3.5h. After the winding is completed, the wound gas cylinder is placed in a curing oven and the final curing is performed according to the thermocuring regime of room temperature → 100℃±5℃ / 1.5h → 135℃±5℃ / 1h → 150℃±5℃ / 12h.

[0079] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A large-diameter, ultra-high-pressure titanium alloy inner liner wound gas cylinder, characterized in that, The gas cylinder comprises a front connector (1), a front end cap (2), a rear end cap (3), and a rear connector (4) welded together in sequence. Both the front end cap (2) and the rear end cap (3) are ellipsoidal in shape. The outer diameter of the gas cylinder... With length The ratio is 0.9~1.1, and a straight section (8) of the cylinder is provided in the middle of the cylinder, and the outer diameter of the cylinder is... Length of the straight segment (8) of the cylinder The ratio is 3.5 to 5.5; The front connector (1) includes a cylindrical nozzle body (5), one end of which is provided with an outer edge (6) for welding to the front end cap (2). The outer edge (6) is perpendicular to the nozzle body (5), and the nozzle body (5) and the outer edge (6) are connected by an arc transition, the radius of which is... =7~12mm, the mouthpiece (5) includes a constant diameter section with a fixed outer diameter and a variable diameter section with a linearly changing outer diameter. The variable diameter section of the mouthpiece (5) is located between the constant diameter section of the mouthpiece (5) and the arc. The diameter of the variable diameter section of the mouthpiece (5) gradually decreases from the constant diameter section of the mouthpiece (5) to the arc. The included angle between the variable diameter section of the mouthpiece (5) and the constant diameter section of the mouthpiece (5) is... =7.5°~12.5°; A welding transition section (7) is provided at the end of the outer edge (6). The front joint (1) is welded to the front end cap (2) through the welding transition section (7). The outer wall of the welding transition section (7) is flush with the outer wall of the front end cap (2). The thickness at the connection between the welding transition section (7) and the outer edge (6) is t1, and the thickness at the weld between the welding transition section (7) and the front end cap (2) is t2, where t2 is the first welding depth. The thickness of the welding transition section (7) changes linearly from one end to the other, so that the inner wall of the welding transition section (7) forms an inclination angle of . The inclined plane, t1, t2 and Between L3 is the length of the welding transition section (7).

2. The large-diameter ultra-high pressure titanium alloy inner liner wound gas cylinder according to claim 1, characterized in that: The welding joint of the front end cap (2) and the rear end cap (3) is located on the straight section (8) of the cylinder. A connecting transition section (9) and a thickened section (10) are sequentially provided at one end of the front end cap (2). The outer wall of the thickened section (10) is flush with the outer wall of the rear end cap (3). One end of the thickened section (10) is welded to the rear end cap (3) and a locking bottom (11) is provided. The locking bottom (11) is located on one side of the inner wall of the rear end cap (3) and fits against the rear end cap (3). The length of the locking bottom (11) is... =1~3mm, the end of the lock bottom (11) is set with a radius of 1~3mm. =0.5~1mm rounded corner, the distance between the lock bottom (11) and the outer wall of the thickened section (10) is the second welding depth The length of the thickened section (10) With the second welding depth The ratio between them is 3~5, and the total length of the connecting transition section (9) and the thickened section (10) is... > The thickness of the connecting transition section (9) varies linearly, and its angle of change is... =15°~45°.

3. A method for manufacturing a large-diameter ultra-high pressure titanium alloy inner liner wound gas cylinder as described in claim 1 or 2, characterized in that, include: S1. Calculate the inner liner volume required to meet the working medium mass based on the working medium pressure and working medium temperature, and determine the outer diameter of the inner liner and the length of the straight section (8) of the inner liner. The inner liner was subjected to strength analysis using finite element analysis to determine the dimensions of the welded structure; S2. Based on the outer diameter of the inner liner, the burst pressure, and the spiral angle of the outer winding layer of the inner liner, calculate the thickness of the circumferential winding layer and the thickness of the spiral winding layer, and calculate the number of layers of the circumferential winding layer and the number of layers of the spiral winding layer. S3. Establish a finite element analysis model of the gas cylinder, analyze the damage mode of the gas cylinder under burst pressure, and obtain the optimal layup mode of the winding layer, as well as the final number of layers of the circumferential winding layer and the final number of layers of the helical winding layer. S4. Perform gas cylinder processing.

4. The large-diameter ultra-high pressure titanium alloy inner liner winding gas cylinder and its manufacturing method according to claim 3, characterized in that: In step S1, the welding structure dimensions between the front connector (1) and the front end cap (2), and between the rear end cap (3) and the rear connector (4) must meet the following requirements: Where t1 is the thickness at the connection between the welding transition section (7) and the outer edge (6), t2 is the first welding depth, and L3 is the length of the welding transition section (7). The inclination angle of the inner wall of the welding transition section (7); The welding structure dimensions of the front end cap (2) and the rear end cap (3) must meet the following requirements: the extension length of the lock bottom (11) =1~3mm, radius of the rounded corner at the end of the lock bottom (11) =0.5~1mm, length of the thickened section (10) With the second welding depth The ratio between them is 3~5, and the total length connecting the transition section (9) and the thickened section (10) is... > The inclination angle of the inner wall of the connecting transition section (9) =15°~45°.

5. The large-diameter ultra-high pressure titanium alloy inner liner winding gas cylinder and its manufacturing method according to claim 3, characterized in that: Step S2 includes: calculating the thickness of the helical winding layer and the circumferential winding layer using the following formulas: , ; In the formula, The thickness of the spiral winding layer, Where R is the thickness of the circumferential winding layer, R is the radius of the inner liner, and P is the thickness of the circumferential winding layer. b For blast pressure, The helix angle, Where k is the allowable fiber strength, and k is the fiber efficiency. This is the stress balance coefficient; Calculate the number of layers in the circumferential winding layer and the number of layers in the helical winding layer based on the thickness of the circumferential winding layer and the thickness of the helical winding layer.

6. The large-diameter ultra-high pressure titanium alloy inner liner winding gas cylinder and its manufacturing method according to claim 3, characterized in that: Step S3 includes: S31. Establish a finite element analysis model of the gas cylinder based on the preset layup pattern; S32. Analyze the damage mode of the gas cylinder under the burst pressure, determine whether there is a damage location in the winding layer. If there is, extract the stress distribution of each winding layer at the damage location, and determine whether the damage location is in the straight section of the cylinder (8). If so, execute step S33; otherwise, execute step S35. S33. Determine whether the average stress of the winding layer at the failure location exceeds the fiber strength, or whether the number of times step S34 is executed exceeds n. If so, increase the number of layers of the circumferential winding layer and execute step S32; otherwise, execute step S34. S34. While maintaining the characteristics of cyclic layup, adjust the layup pattern and execute step S32; S35. Determine whether the average stress of the winding layer at the failure location exceeds the fiber strength, or whether the number of times step S36 is executed exceeds n. If so, increase the number of spiral winding layers and execute step S32; otherwise, execute step S36. S36. While maintaining the characteristics of cyclic layup, adjust the layup pattern and execute step S32.

7. The large-diameter ultra-high pressure titanium alloy inner liner winding gas cylinder and its manufacturing method according to claim 3, characterized in that: Step S4 includes: S41. Heat-treat the titanium alloy bar and process it into a front connector (1) and a rear connector (4). Inspect the surface defects of the front connector (1) and the rear connector (4). Heat-treat the titanium alloy plate and process it into a front end cap (2) and a rear end cap (3). S42. Pickling is used to treat the surfaces of the front joint (1), front end cap (2), rear end cap (3), and rear joint (4). Electron beam welding is used to weld the front joint (1) and front end cap (2), and the rear joint (4) and rear end cap (3). After welding, the weld excess height on the inner and outer surfaces is ground. Finally, the front end cap (2) and rear end cap (3) are welded to complete the cylinder assembly. The weld excess height on the outer surface is ground, and the weld quality is inspected by X-ray. S43. Sandblast the outer surface of the inner liner that needs to be wrapped, and apply adhesive to the outer surface of the inner liner. S44. Calculate the initial tension F0 of the winding layer using a tension reduction system of decreasing F for every m winding layer. Wind the inner liner with the initial tension F0. During the winding process, pressurized gas is injected into the inner liner to counteract the tension of the winding layer. S45. When the thickness of the winding layer reaches 5mm, perform the first pre-curing. After the winding is completed, perform the final curing.

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