A method for manufacturing a large-capacity high-pressure hydrogen cylinder

Abstract

The application discloses a manufacturing method of a large-capacity high-pressure hydrogen storage cylinder, which comprises the following steps: taking a round sheet as a base material, stretching the round sheet to form a second cup-shaped body blank, spinning the second cup-shaped body blank to form a third cup-shaped body blank, cutting the opening side of the third cup-shaped body blank to make the end face flat, cleaning the third cup-shaped body blank, performing a closing process on the opening side of the third cup-shaped body blank to form the overall shape of an inner container, cutting the head of the inner container to make the end face flat, performing heat treatment on the inner container, cleaning the inner container, and winding carbon fibers on the surface of the inner container.

Description

Technical Field

[0001] This application relates to the technical field of hydrogen storage cylinder manufacturing, and in particular to a method for manufacturing a large-capacity, high-pressure hydrogen storage cylinder. Background Technology

[0002] Hydrogen energy, as a secondary clean energy source, is one of the key energy sources that can be developed at present. Hydrogen is in liquid form under low temperature and high pressure and can be stored in high-pressure cylinders, and can be used as a power source. However, for safety reasons, there are higher requirements for the containers used to store liquid hydrogen.

[0003] Currently, hydrogen cylinder liners are typically manufactured by extruding aluminum ingots using stamping equipment. For example, the invention patent CN115382984A discloses a "stamping method and deep drawing die for an aluminum alloy liner of a large-capacity hydrogen storage cylinder." In this method, the aluminum ingot is heated and repeatedly stamped into a cup shape. To control the liner thickness, subsequent machining is usually required. This production method easily compromises the integrity of the liner, especially in the production of large-capacity cylinder liners, posing a certain safety hazard for hydrogen storage. Summary of the Invention

[0004] In order to improve the pressure resistance of gas cylinders, this application provides a method for manufacturing a large-capacity high-pressure hydrogen storage cylinder.

[0005] The manufacturing method of a large-capacity, high-pressure hydrogen storage cylinder provided in this application adopts the following technical solution: A method for manufacturing a large-capacity, high-pressure hydrogen storage cylinder includes the following steps: Step 1: Using a circular sheet as the substrate, stretch it to form a second cup-shaped blank; Step 2: The second cup-shaped blank is spun and formed into a third cup-shaped blank, so that its length and thickness meet the design requirements; Step 3: Make a cut on the open side of the third cup-shaped blank to make its end face flat; Step 4: Clean the third cup-shaped blank; Step 5: Tighten the opening side of the third cup-shaped blank to form the overall shape of the inner liner. Step 6: Cut the end of the inner liner at the seam to make the end face flat; Step 7: Heat treatment of the inner liner; Step 8: Clean the inner liner; Step 9: Wrap carbon fiber around the surface of the inner liner.

[0006] Preferably, step 1 includes: Step 1-1: The circular sheet is stretched and shaped to form the first cup-shaped blank; Steps 1-2: The first cup-shaped blank undergoes tempering treatment; Steps 1-3: The first cup-shaped blank is stretched a second time to increase the overall height and reduce the thickness to form the second cup-shaped blank.

[0007] Preferably, in step 1-1, the disc is positioned between the first upper mold and the first lower mold. The first upper mold has a first forming hole, the first lower mold has a first clearance hole, and the first punch is set in the first clearance hole of the first lower mold. The first upper mold moves downward and pushes the first lower mold downward. At the same time, the first punch moves upward and squeezes the disc, causing the disc to gradually pass through the first forming hole to form the first cup-shaped blank. In steps 1-3, the open side of the first cup-shaped blank is placed on the second punch. The second upper die has a second forming hole, and the second lower die has a second clearance hole. The second punch is placed in the second clearance hole. The second upper die moves downward and the second punch moves upward, simultaneously squeezing the first cup-shaped blank and causing the first cup-shaped blank to gradually pass through the second forming hole to form the second cup-shaped blank. The diameter of the second forming hole is smaller than the diameter of the first forming hole.

[0008] Preferably, in step 1, the disc is positioned between the third upper mold and the third lower mold. The third upper mold has a third forming hole and a fourth forming hole in the vertical direction. The third lower mold has a third clearance hole. The third punch is set in the clearance hole of the third lower mold. The third upper mold moves downward and drives the third lower mold to move downward. At the same time, the third punch moves upward and squeezes the disc, so that the disc is formed into a first cup-shaped blank after passing through the third forming hole. After passing through the fourth forming hole, a second cup-shaped blank is formed. The diameter of the fourth forming hole is smaller than the diameter of the third forming hole. The third upper mold is provided with a heating tube at the outer edge of the third forming hole. When the disc passes through the third forming hole, the heating tube works to heat the formed first cup-shaped blank.

[0009] Preferably, in step 1, stretching oil is applied to both sides of the disc before stretching.

[0010] Preferably, the heat treatment in step 7 is solution heat treatment, the disc material is aluminum alloy, the heating temperature in the solution furnace is between 525±10℃, after the temperature reaches 525℃, it is held for 120±15min, after the holding time is completed, the inner liner is transferred from the solution furnace to the cooling water, the time from exiting the furnace to entering the cooling water is no more than 10s, the cooling water temperature is between 15-45℃, and the cooling immersion time is no less than 10min.

[0011] Preferably, multiple inner liners are smoothly installed into a stainless steel frame, and the entire stainless steel frame is hoisted into the solution furnace. During cooling, the entire stainless steel frame is immersed in a cooling water tank. When the inner liners are immersed in the cooling water tank, the bottle openings face downwards so that cooling water can quickly enter the inner cavity of the inner liners. The solution furnace has a bottom-opening structure, and when the inner liners are removed from the furnace for cooling, the cooling water tank is placed below the opening of the solution furnace.

[0012] Preferably, the stainless steel frame includes multiple limiting stations, each of which includes a U-shaped connecting pipe. When the inner liner is installed at a limiting station, the pressure plate abuts against one end face of the inner liner opposite the bottle opening. One end of the connecting pipe extends from the opening of the inner liner into the inner cavity. After the stainless steel frame is immersed in the cooling water tank, the other end of the connecting pipe is always above the liquid surface of the cooling water tank.

[0013] Preferably, the end of the connecting tube inserted into the inner liner is no less than 1 / 2 of the total height of the inner liner, and the ratio of the diameter of the connecting tube inserted into the inner liner to the diameter of the inner liner bottle opening is between 1:5 and 1:8.

[0014] Preferably, step 9 includes: Step 9-1: Apply insulating varnish to the outer surface of the inner liner; Step 9-2: Apply adhesive to the carbon fiber surface and wrap it around the outer surface of the inner liner in four winding patterns: first circumferential winding, spiral winding, longitudinal winding, and second circumferential winding, with the starting end of the last winding process being the end of the previous winding process. Step 9-3: Curing treatment; Step 9-4: Coat the carbon fiber surface with a layer of flexible epoxy adhesive.

[0015] In summary, this application includes at least one of the following beneficial technical effects: 1. A cup-shaped blank is formed by stretching a round sheet as the base material in one or more steps, and the inner liner is formed by spinning and necking processes. This eliminates the need for machining to correct the wall thickness after the inner liner is formed, maintains the integrity of the inner liner, and improves the safety of use. 2. The solution treatment process for the aluminum alloy inner liner, using a bottom-opening solution furnace structure, enables rapid water cooling of the inner liner. The purpose of rapid cooling is to freeze the single-phase solid solution and prevent solute atoms from precipitating prematurely. At the same time, when the inner liner is immersed in water, the bottle opening faces downwards, and the connecting pipe structure allows the inner and outer walls of the inner liner to be cooled simultaneously. This reduces the excessive temperature difference between the inner and outer walls, which could lead to thermal stress imbalance and reduce the defects caused by tensile stress due to external contraction and internal expansion that could damage the integrity of the inner liner and form small cracks, thus further improving the integrity of the inner liner. 3. After the inner liner is formed, carbon fiber is wound around the outer surface to further improve the pressure resistance of the inner liner. The lightweight nature of carbon fiber reduces the overall weight of the gas cylinder after forming. In addition, the use of four layers of carbon fiber wound in sequence improves the radial pressure resistance and axial bending resistance of the gas cylinder after forming. At the same time, the stress can be evenly distributed on the surface of the gas cylinder when the end of each winding is connected to the beginning end. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the process of stretching the disc in the first step in Example 1; Figure 2 This is a schematic diagram of the process of the cup-shaped blank during the second stretching in Example 1; Figure 3 This is a process diagram illustrating the forming of the cup-shaped blank in Example 1; Figure 4 This is a schematic diagram of the process for forming a cup-shaped blank from a round disc in Example 2; Figure 5 This is a schematic diagram of the spinning process in Example 1; Figure 6 This is a schematic diagram of the closing process in Example 1; Figure 7 This is a schematic diagram of the solution furnace used in the solution treatment in Example 1; Figure 8 This is a schematic diagram showing the position between the cooling water tank and the furnace body, as illustrated in Example 1. Figure 9 This is a front view of the furnace body in Example 1; Figure 10 This is a schematic diagram of the installation of the inner liner in the stainless steel frame in Example 1; Figure 11 This is a schematic diagram of the inner tank cooling in the cooling water tank in Embodiment 1; Figure 12 This is a schematic diagram showing the diameter ratio between the connecting tube and the inner bottle opening in Example 1; Figure 13 This is a schematic diagram of the first circumferential winding in Example 1; Figure 14 This is a schematic diagram of the spiral winding in Example 1; Figure 15 This is a schematic diagram of the longitudinal winding in Example 1; Figure 16 This is a schematic diagram of the second reversing winding in Example 1; Figure 17 This is a Von Mises equivalent stress distribution diagram under zero pressure after the gas cylinder liner self-tightens in Example 1; Figure 18This is a diagram showing the compressive stress distribution of the inner liner of the gas cylinder under zero pressure after self-tightening in Example 1. Figure 19 This is a Von Mises equivalent stress distribution diagram under zero pressure after the winding layer self-tightens in Example 1; Figure 20 This is a Von Mises equivalent stress distribution diagram under working pressure after the gas cylinder liner self-tightens in Example 1; Figure 21 This is a diagram showing the compressive stress distribution of the inner liner of the gas cylinder under working pressure after self-tightening in Example 1. Figure 22 This is a Von Mises equivalent stress distribution diagram of the winding layer after self-tightening under working pressure in Example 1; Figure 23 This is a Von Mises equivalent stress distribution diagram under test pressure after the gas cylinder liner self-tightens in Example 1; Figure 24 This is a Von Mises equivalent stress distribution diagram of the winding layer after self-tightening under test pressure in Example 1; Figure 25 This is a Von Mises equivalent stress distribution diagram of the gas cylinder liner after self-tightening under burst pressure in Example 1; Figure 26 This is a Von Mises equivalent stress distribution diagram of the winding layer after self-tightening under burst pressure in Example 1.

[0017] Explanation of reference numerals in the attached drawings: 10. Circular piece; 11. First cup-shaped blank; 12. Second cup-shaped blank; 13. Third cup-shaped blank; 14. Inner liner; 141. Inner cavity; 142. Upper end; 143. Middle section; 144. Lower end; 20. First upper mold; 21. First forming hole; 30. First lower mold; 31. First clearance hole; 40. First punch; 50. Second upper mold; 51. Second forming hole; 60. Second lower mold; 61. Second clearance hole; 70. Second punch; 80. Third upper mold; 81. First mold body; 811. Third forming hole; 8 2. Second mold body; 821. Fourth forming hole; 822. Heating tube; 83. Third lower mold; 831. Third clearance hole; 84. Connecting column; 90. Third punch; 91. First top cylinder; 92. Second top cylinder; 100. Rotating shaft; 110. First spinning wheel; 120. Turntable claw; 121. Second spinning wheel; 130. Solution furnace; 131. Furnace body; 132. Cooling water tank; 133. Moving trolley; 134. Stainless steel frame; 1341. Frame; 1342. Clamp; 1343. Connecting pipe; 1344. Limiting plate; 135. Furnace door. Detailed Implementation

[0018] The present application will be further described in detail below with reference to the accompanying drawings.

[0019] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Example 1

[0021] A method for molding and manufacturing a large-capacity hydrogen cylinder inner liner 14 includes the following steps: Step 1 includes: Step 1-1, see below Figure 1 As shown, an aluminum alloy disc is placed between the first upper die 20 and the first lower die 30 in a stretching machine for the first stretching. Before the first stretching, a layer of stretching oil is evenly brushed on both surfaces of the disc 10. When the stretching machine is working, the first upper die 20 moves toward the first lower die 30 and the two collide and move down synchronously. The first punch 40 is installed at the bottom of the stretching machine and connected to the bottom drive component. The first punch 40 is driven by the drive component to move toward the first lower die 30 and extrude the disc 10. The first upper die 20 has a first forming hole 21 in the middle and the first lower die 30 has a first clearance hole 31 in the middle. The first punch 40 passes through the first clearance hole 31 and extrudes the disc 10, which gradually passes through the first forming hole 21. The disc 10 is extruded through the outer peripheral wall of the first forming hole 21 to form the first cup-shaped blank 11.

[0022] Steps 1-2: The first cup-shaped blank 11 is tempered.

[0023] Steps 1-3: The first cup-shaped blank 11 is stretched a second time. The first cup-shaped blank 11 is placed on the second punch 70 of another stretching machine. The second upper die 50 moves toward the second lower die 60. The second punch 70 is set at the bottom of the stretching machine and is also driven to rise and fall by the drive component. The second upper die 50 has a second forming hole 51 and the second lower die 60 has a second clearance hole 61. The diameter of the second forming hole 51 is smaller than the diameter of the first forming hole 21.

[0024] During the second stretching process, the second upper die 50 moves toward the side of the second lower die 60, and the second punch 70 moves toward the side of the second upper die 50. After the first cup-shaped blank 11 passes through the second forming hole 51, it forms the second cup-shaped blank 12.

[0025] Combination Figure 3 The second cup-shaped blank 12 is taller and thinner than the first cup-shaped blank 11.

[0026] Step 2, see Figure 5 The second cup-shaped blank 12 is mounted on the rotating shaft 100 of the spinning machine. The tail end presses against one end of the second cup-shaped blank 12 and can rotate synchronously with the rotating shaft 100. During spinning, the first spinning wheel 110 abuts against the outer wall of the second cup-shaped blank 12 and gradually moves away from the tail end along the axial direction of the rotating shaft 100. The first spinning wheel 110 has three wheels evenly distributed around the circumference of the rotating shaft 100. After spinning, the wall thickness of the second cup-shaped blank 12 decreases and its height increases to obtain the third cup-shaped blank 13.

[0027] Step 3: The third cup-shaped blank 13 is cut at the opening side on the machine tool to make its height meet the design requirements and the end face flattened.

[0028] Step 4: Clean the third cup-shaped blank 13 to remove surface dirt and impurities.

[0029] Step 5, see Figure 6 The third cup-shaped blank 13 is clamped onto the rotating jaws of the machine tool spindle, with the open side facing outwards. The high-temperature spray gun is turned on to heat the open part, and the rotation of the machine tool spindle drives the third cup-shaped blank 13 to rotate. The second spinning roller 121 gradually squeezes the outer wall of the open side to close the opening and form the overall shape of the inner liner 14.

[0030] Step 6: Use a machine tool cutter to flatten the end face on the opening side of the inner liner 14 at the closing position.

[0031] Step 7, combined Figures 7 to 11 The formed inner liner 14 is then heat-treated by solution treatment. Multiple inner liners 14 are first installed onto a stainless steel frame 134. The stainless steel frame 134 includes a frame body 1341, which has multiple limiting positions. Each limiting position can accommodate one inner liner 14 for installation and limiting. Each limiting position has multiple clamps 1342 arranged vertically and a U-shaped connecting pipe 1343, which is fixed to the frame body 1341.

[0032] When fixing the inner liner 14, first insert the inner liner 14 into the connecting pipe 1343 from the opening position, so that one end of the connecting pipe 1343 is placed in the inner cavity 141 of the inner liner 14. Then move the inner liner 14 and make its bottom abut against the limiting plate 1344 on the frame 1341 to realize the travel limit on one side of the inner liner 14. Finally, the clamp 1342 hugs the inner liner 14 so that the entire inner liner 14 is completely connected to the frame 1341.

[0033] The solution treatment uses a solution furnace 130. In this embodiment, the solution furnace 130 includes a furnace body 131, which is a bottom-opening type. Furnace doors 135 are provided on both sides of the opening of the furnace body 131. The two furnace doors 135 are driven by a drive unit on a track and can move towards each other or away from each other. When the two doors move towards each other and collide with each other, they can close the opening of the furnace body 131 to achieve furnace closure.

[0034] A cooling water tank 132 is provided below the opening of the furnace body 131, and a moving trolley 133 is provided on one side of the cooling water tank 132. During the solution treatment, the stainless steel frame 134 is first hoisted onto the moving trolley 133 by the truss. The moving trolley 133 slides to the opening of the furnace body 131, the two furnace doors 135 are opened, and the entire stainless steel frame 134 is hoisted into the furnace body 131 by the electric hoist of the solution furnace 130. The furnace doors 135 are then closed for heating treatment.

[0035] During the heat treatment, the heating temperature is between 525±10℃. After reaching 525℃, the temperature is held for 120±15 minutes. After the holding time is completed, the furnace door 135 is opened, and the entire stainless steel frame 134 is hoisted into the cooling water tank 132. When the inner tank 14 is submerged in water, the opening side faces the cooling water tank 132. The inner and outer walls of the inner tank 14 can be simultaneously cooled by contacting the cooling water under the action of the connecting pipe 1343. The time from exiting the furnace to entering the cooling water is no more than 10 seconds. The cooling water temperature is between 15-45℃, and the cooling immersion time is no less than 10 minutes. At the solution treatment temperature, the second phase (such as Mg2Si, CuAl2) of aluminum alloys completely dissolves into the aluminum matrix, forming a uniform supersaturated solid solution. If the cooling rate is too slow, solute atoms (Mg, Cu, etc.) in the supersaturated solid solution will precipitate prematurely during the cooling process, forming coarse second-phase particles. These prematurely precipitated coarse particles will prevent the formation of a uniform and fine strengthening phase during subsequent aging treatment, directly reducing the final strength and hardness of the material and negating the purpose of solution treatment. Therefore, in this embodiment, the bottom-opening door structure of the furnace body 131 can reduce the time required for the inner liner 14 to transfer to the cooling water tank 132, allowing it to enter the cooling water as quickly as possible to achieve the effect of solution treatment.

[0036] Combination Figure 12The height H1:H2 of the connecting tube 1343 inserted into the inner cavity 141 is greater than 1 / 2. At the same time, the ratio of the diameter φ2 of the connecting tube 1343 to the orifice diameter φ1 of the inner liner 14 is between 1:5 and 1:8. Meanwhile, the other end of the connecting tube 1343 is always placed on the liquid surface of the cooling water tank 132.

[0037] Based on the bottle opening size, ensure that water inlet and venting do not interfere with each other. The following are instructions for selecting the connecting pipe diameter for different bottle opening diameters: If the aperture ratio is less than 1:5, it will affect the water intake. If the aperture ratio is greater than 1:8, it will easily lead to insufficient exhaust speed. The high-temperature gas in the inner cavity 141 cannot be discharged in time, and may leave local air plugs, which will affect the cooling effect.

[0038] After the solution treatment is completed, the stainless steel frame is lifted from the cooling water tank 132, gently placed on the trolley, and pushed into the aging furnace. The furnace temperature is 180±10℃, and the aging holding time is ≥480±60min. After aging is completed, the inner liner 14 is naturally cooled in the air.

[0039] Step 8: The inner liner 14 undergoes a final cleaning process using spray cleaning. After cleaning, the manufacturing process of the entire inner liner 14 is complete.

[0040] Step 9, see Figures 13 to 16 ,include: Step 9-1: Apply insulating varnish to the outer surface of the inner liner 14. This insulating varnish acts as a barrier between the inner liner 14 and the subsequent carbon fiber to reduce the possibility of leakage caused by galvanic corrosion.

[0041] Step 9-2: Perform the first circumferential winding on the outer surface of the inner liner 14. Before winding, apply glue to the surface of the carbon fiber and start from the upper end 142 of the inner liner 14 to wind the outer surface of the upper end 142, the middle section 143 and the lower end 144 in a horizontal circumferential direction.

[0042] After completing the first circumferential winding, spiral winding is carried out. The end of the first circumferential winding, i.e. the lower end 144, is used as the starting end of spiral winding. The spiral winding is carried out continuously from the lower end 144 to the upper end 142 at a horizontal angle of 5-10°.

[0043] After completing the spiral winding, longitudinal winding is carried out, with the end of the spiral winding, i.e. the upper end 142, as the starting point of the longitudinal winding, and the winding is carried out vertically.

[0044] Finally, the second reversing winding is carried out, starting from the end of the longitudinal winding, i.e. the lower end 144, and the outer surfaces of the lower end 144, the middle section 143, and the upper end 142 are wound in a horizontal circumferential direction.

[0045] The first circumferential winding can preferentially strengthen the pressure resistance of the gas cylinder in the circumferential direction, resist the radial expansion force brought by high-pressure hydrogen, and lay the foundation for basic pressure resistance performance.

[0046] Helical winding compensates for the strength deficiency of circumferential winding in the axial (length direction), while connecting circumferential and longitudinal forces, dispersing local stress concentration, and improving the overall structural stability.

[0047] The longitudinal winding points enhance the axial tensile and bending resistance of the gas cylinder, preventing tensile deformation or cracking at both ends of the gas cylinder under high pressure, and are suitable for stress scenarios during transportation and installation.

[0048] The second circumferential winding further strengthens the radial pressure resistance, locks the inner winding structure, reduces fatigue loss under long-term high-pressure use, and improves the service life of the gas cylinder.

[0049] Meanwhile, the starting point of the next winding is the end of the previous winding. This winding method allows the winding layers to be tightly connected, forming a continuous integral structure. Starting the next winding from the end of the previous one effectively avoids obvious gaps or weak points between the winding layers, thereby improving the overall mechanical properties and sealing of the gas cylinder, and better withstanding the pressure of the internal high-pressure hydrogen gas.

[0050] Secondly, it allows for a more uniform distribution of stress on the cylinder surface. Each winding is performed based on the previous one, enabling gradual adjustment and balance of stress in different directions, preventing stress concentration in certain specific areas. For example, circumferential winding primarily bears radial stress, while helical and longitudinal windings function in the axial and other directions, respectively. This sequential connection method allows various stresses to cancel each other out and balance, improving the cylinder's fatigue resistance and service life.

[0051] Step 9-3: Place the wrapped gas cylinder into a curing oven for curing treatment to cure the adhesive. The temperature range of the curing oven is 120-180℃, and the curing time is 1 hour. The adhesive used is E-54 epoxy resin.

[0052] Step 9-4: After curing, apply a layer of flexible epoxy adhesive to the surface of the gas cylinder to improve the wear resistance of the carbon fiber layer, reduce scratches, and improve corrosion resistance.

[0053] See also Figures 17 to 26 The stress distribution diagrams of the inner liner and winding layer under four pressure dimensions—zero pressure, working pressure, test pressure, and burst pressure—were generated using Ansys Workbench 2020 R2 finite element analysis software.

[0054] The following is a reference for zero pressure: The pre-tightening force of the winding layer generates compressive stress in the inner liner, which counteracts the tensile stress under subsequent high-pressure conditions, thus establishing "stress compensation" in advance and improving the overall pressure resistance.

[0055] The following is a reference for working pressure (35MPa): Under working pressure, hydrogen gas exerts an outward thrust on the inner wall of the liner, causing the liner to undergo tensile deformation; however, due to the pre-tightening of the winding layer and the high tensile strength of carbon fiber, most of the tensile force is borne by the winding layer, and the tensile stress of the liner is controlled within a safe range, making the winding layer the main load-bearing layer.

[0056] The following is a reference for the test pressure (52.5 MPa): Although the tensile stress of the inner liner increased under the test pressure, it did not reach the yield limit, and the winding layer simultaneously bore more load, ensuring that the overall structure did not fail.

[0057] The following is a reference for the test pressure (102 MPa): Under extreme burst pressure, the tensile effect of hydrogen on the inner liner reaches its maximum, and the inner liner is close to yielding; however, the outer winding layer, through the high tensile strength of carbon fiber, disperses the total load and prevents the inner liner from failing before the winding layer. Example 2

[0058] A method for molding and manufacturing a large-capacity hydrogen cylinder inner liner 14 differs from Example 1 in that the circular sheet 10 is directly formed into the second cup-shaped blank 12 through a single stretching process. See details... Figure 4 The disc 10 is placed between the third upper mold 80 and the third lower mold 83. The third upper mold 80 includes a first mold body 81, a second mold body 82, and a connecting post 84 connecting the first mold body 81 and the second mold body 82. The first mold body 81 has a third forming hole 811, and the second mold body 82 has a fourth forming hole 821. The diameter of the third forming hole 811 is smaller than the diameter of the fourth forming hole 821, and the first mold body 81 is placed above the second mold body 82. The third lower mold 83 has a third clearance hole 831.

[0059] During stretching, the third upper die 80 moves towards the third lower die 83 and moves down synchronously after contacting it. The third punch 90 is placed at the bottom of the stretching machine. The third punch 90 includes a first top cylinder 91 and a second top cylinder 92. The second top cylinder 92 can extend and retract relative to the first top cylinder 91, and the second top cylinder 92 can extend and retract independently. When the third upper die 80 and the third lower die 83 move down synchronously, the second top cylinder 92 extends through the third clearance hole 831 and squeezes the disc 10 so that it gradually passes through the third forming hole 811 to form the first cup-shaped blank 11. The third upper die 80 continues to move down. At this time, the second top cylinder 92 extends relative to the first top cylinder 91 and squeezes the first cup-shaped blank 11 to gradually pass through the second forming hole 51 to form the second cup-shaped blank 12.

[0060] As the disc 10 gradually passes through the third forming hole 811, a heating tube 822 is provided inside the second mold body 82. The heating tube 822 is a heating coil. The heating tube 822 heats the second mold body 82, thereby heating the first cup-shaped blank 11 to facilitate the forming of the second cup-shaped blank 12.

[0061] Compared to multi-pass stretching forming processes, this embodiment uses a single stretching process, which improves forming efficiency.

[0062] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for manufacturing a large-capacity, high-pressure hydrogen storage cylinder, characterized in that, Includes the following steps: Step 1: The circular piece (10) is stretched and formed into a second cup-shaped blank (12). Step 2: The second cup-shaped blank (12) is spun and formed into a third cup-shaped blank (13) so that its length and thickness meet the design requirements; Step 3: Make a cut on the open side of the third cup-shaped blank (13) to make its end face flat; Step 4: Clean the third cup-shaped blank (13); Step 5: The opening side of the third cup-shaped blank (13) is closed to form the overall shape of the inner liner (14); Step 6: Cut the end of the inner liner (14) at the closing point to make its end face flat; Step 7: Heat treatment of the inner liner (14). The heat treatment is solution heat treatment. The material of the disc (10) is aluminum alloy. Multiple inner liners (14) are installed smoothly into the stainless steel frame (134). The stainless steel frame (134) is hoisted into the solution furnace (130). The heating temperature in the solution furnace (130) is between 525±10℃. After the temperature reaches 525℃, it is kept warm for 120±15 minutes. After the heat preservation is completed, the inner liner (14) is transferred to the cooling water after it comes out of the solution furnace (130). During cooling, the stainless steel frame (134) is completely immersed in the cooling water tank (132). The solution furnace (130) has a bottom-opening structure. When the inner liner (14) is cooled after being taken out of the furnace, the cooling water tank (132) is placed below the opening of the solution furnace (130). When the stainless steel frame (134) is immersed in the cooling water tank (132), the bottle mouth is facing down so that the cooling water can quickly enter the inner cavity (141) of the inner liner (14). The stainless steel frame (134) includes multiple limiting positions, and each limiting position includes a U-shaped connecting pipe (1343). After the inner liner (14) is installed at the limiting position, the pressure plate abuts against one end face of the inner liner (14) opposite to the bottle mouth. One end of the connecting pipe (1343) extends from the opening of the inner liner (14) into the inner cavity (141). After the stainless steel frame (134) is immersed in the cooling water tank (132), the other end of the connecting pipe (1343) is always above the liquid surface of the cooling water tank (132). The time from the furnace exit to the entry into the cooling water transfer is no more than 10 seconds. The cooling water temperature is between 15-45℃, and the cooling soaking time is no less than 10 minutes. Step 8: Clean the inner liner (14); Step 9: The inner liner (14) surface is wrapped with carbon fiber.

2. The method for manufacturing a large-capacity high-pressure hydrogen storage cylinder according to claim 1, characterized in that, Step 1 includes: Step 1-1: The circular piece (10) is stretched and formed into the first cup-shaped blank (11). Steps 1-2: The first cup-shaped blank (11) is tempered; Steps 1-3: The first cup-shaped blank (11) is stretched a second time to increase the overall height and reduce the thickness to form the second cup-shaped blank (12).

3. The method for manufacturing a large-capacity high-pressure hydrogen storage cylinder according to claim 2, characterized in that, In step 1-1, the disc (10) is positioned between the first upper mold (20) and the first lower mold (30). The first upper mold (20) has a first forming hole (21), and the first lower mold (30) has a first clearance hole (31). The first punch (40) is set in the first clearance hole (31) of the first lower mold (30). The first upper mold (20) moves downward and pushes the first lower mold (30) downward. At the same time, the first punch (40) moves upward and squeezes the disc (10) so that the disc (10) gradually passes through the first forming hole (21) to form the first cup-shaped blank (11). In steps 1-3, the opening side of the first cup-shaped blank (11) is placed on the second punch (70). The second upper die (50) has a second forming hole (51), and the second lower die (60) has a second clearance hole (61). The second punch (70) is placed in the second clearance hole (61). The second upper die (50) moves downward and the second punch (70) moves upward, while simultaneously squeezing the first cup-shaped blank (11) and causing the first cup-shaped blank (11) to gradually pass through the second forming hole (51) to form the second cup-shaped blank (12). The diameter of the second forming hole (51) is smaller than the diameter of the first forming hole (21).

4. The method for manufacturing a large-capacity high-pressure hydrogen storage cylinder according to claim 1, characterized in that, In step 1, the disc (10) is positioned between the third upper die (80) and the third lower die (83). The third upper die (80) has a third forming hole (811) and a fourth forming hole (821) in the vertical direction. The third lower die (83) has a third clearance hole (831). The third punch (90) is set in the clearance hole of the third lower die (83). The third upper die (80) moves downward and drives the third lower die (83) downward. At the same time, the third punch (90) moves upward and squeezes the disc (10) so that the disc (10) passes through The first cup-shaped blank (11) is formed after the third forming hole (811), and the second cup-shaped blank (12) is formed after passing through the fourth forming hole (821). The diameter of the fourth forming hole (821) is smaller than that of the third forming hole (811). The third upper mold (80) is provided with a heating tube (822) at the outer edge of the third forming hole (811). When the disc (10) passes through the third forming hole (811), the heating tube (822) heats the first cup-shaped blank (11) formed.

5. A method for manufacturing a large-capacity high-pressure hydrogen storage cylinder according to claim 1 or 4, characterized in that, Before stretching in step 1, stretching oil is applied to both sides of the disc (10).

6. The method for manufacturing a large-capacity high-pressure hydrogen storage cylinder according to claim 1, characterized in that, The end of the connecting tube (1343) inserted into the inner liner (14) is no less than 1 / 2 of the height of the entire inner liner (14), and the ratio of the diameter of the connecting tube (1343) inserted into the inner liner (14) to the diameter of the bottle mouth of the inner liner (14) is between 1:5 and 1:

8.

7. The method for manufacturing a large-capacity high-pressure hydrogen storage cylinder according to claim 6, characterized in that, Step 9 includes: Step 9-1: Apply insulating varnish to the outer surface of the inner liner (14); Step 9-2: Apply glue to the carbon fiber surface and wrap it around the outer surface of the inner liner (14) in four winding forms: first circumferential winding, spiral winding, longitudinal winding and second circumferential winding, with the starting end of the last winding process being the end of the previous winding process. Step 9-3: Curing treatment; Step 9-4: Coat the carbon fiber surface with a layer of flexible epoxy adhesive.

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