Manufacturing method of integrated rubber liner carbon fiber composite gas cylinder

Abstract

The invention relates to a manufacturing method of an integrated rubber liner carbon fiber composite material gas storage cylinder. The manufacturing method comprises the following steps: S1, prefabricating a rubber liner: forming an unvulcanized rubber tube blank by adopting butadiene styrene rubber or natural rubber or hydrogenated nitrile rubber or fluororubber through rotary mould pressing or mould pressing; s2, pre-pressurizing the inner container; S3, forming the seamless inner container; s4, functionalizing the surface of the inner container; s5, interface glue coating; s6, performing prepreg or wet-process layering; s7, curing; and S8, post-processing. Through spiral microgroove interface enhancement, pre-pressurized expansion compensation and a low-cost resin system, production of the heavy truck gas storage cylinder is achieved, the production cost is reduced, and the production efficiency is improved; the rubber inner container is integrally formed, and the carbon fiber gas storage bottle is manufactured by taking the inner container as a support, so that the sealing performance can be improved, and the weight can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material high-pressure container manufacturing, and in particular to a method for manufacturing an integrated rubber liner carbon fiber composite material gas storage cylinder. Background Art

[0002] Key subsystems of heavy trucks, such as the braking system and air suspension, rely heavily on high-pressure air as a power source. Air reservoirs are core components for ensuring driving safety. Traditional steel air reservoirs face the following technical bottlenecks in long-term use:

[0003] Excessive weight: The weight of the steel cylinder significantly increases the vehicle mass, reduces payload capacity, and increases fuel / power consumption (compliance requirements: GB 1589-2016 and other regulations have strict restrictions on commercial vehicle axle loads);

[0004] Insufficient corrosion resistance: Rust easily occurs in environments such as humidity, salt spray, and snow-melting agents, resulting in thinning of wall thickness, reduced pressure-bearing capacity, and the risk of bursting (industry pain point: corrosion failure accounts for more than 30% of the failure rate of gas cylinders);

[0005] Limited fatigue life: Frequent charging and discharging (working pressure 0.7–1.0 MPa) and road vibration and impact accelerate the growth of fatigue cracks in welds / base materials (technical requirement: must meet ≥1 million pressure cycle life);

[0006] Low space utilization: The cylindrical steel drum has a rigid layout and is difficult to fit into the compact chassis space (demand trend: electric / hydrogen heavy trucks urgently need lightweighting and space optimization);

[0007] The manufacturing process is complex: coil welding + anti-corrosion treatment involves many steps, high energy consumption, and the welds are potential failure points.

[0008] To solve the above problems, the use of composite materials to manufacture heavy-duty truck gas cylinders is a key strategy. Heavy-duty truck gas cylinders need to meet the technical requirements of lightweight and low cost. The use of carbon fiber composite materials has significant advantages. The existing composite material gas cylinder (gas cylinder) manufacturing methods include: 1. Metal core mold method: After the aluminum alloy core mold is wound, it needs to be acid-etched and demolded. The demolding of a single piece takes a long time (>4h), and the residual acid corrodes the fiber layer (the scrap rate is >10%); 2. Soluble core mold method: After the salt core mold (NaCl) is formed, it needs to be rinsed with deionized water for 12 to 24h. The residual chloride ions cause interface corrosion and the leakage rate is ≥1×10 -4 mbar·L / s; 3. Thermoplastic liner method: The demolding temperature of the nylon liner is above 100°C, resulting in rubber aging and increased energy consumption (energy consumption per unit > 30kWh); 4. Interface bonding failure: The peel strength of the existing epoxy adhesive layer under long-term vibration is ≤0.3N / mm, resulting in delamination between the liner and the fiber layer and seal failure.

[0009] The manufacturing of traditional carbon fiber gas cylinders relies on automated winding equipment, which has high equipment costs and is difficult to adapt to complex and special-shaped structures; manual laying is flexible, but there are problems such as bubbles between layers and uneven fiber tension, resulting in insufficient strength; and traditional manufacturing methods are expensive, which also limits the market promotion and application of composite gas cylinders. In addition, the rubber liner is easily deformed by external forces during manual laying, affecting the airtightness. Summary of the Invention

[0010] The present invention is to solve the above problems and provides a method for manufacturing an integrated rubber liner carbon fiber composite material gas storage cylinder. The process uses an internal expansion method to form a rubber liner and combines it with a layup process to prepare a low-cost carbon fiber gas storage cylinder.

[0011] The technical solution of the manufacturing method of the one-piece rubber liner carbon fiber composite material gas storage cylinder of the present invention is:

[0012] The following steps are involved:

[0013] S1 rubber liner prefabrication: using styrene-butadiene rubber or natural rubber or hydrogenated nitrile rubber or fluororubber to form unvulcanized rubber tube blanks by rotational molding or compression molding;

[0014] S2 Pre-pressurization of liner: Insert the unvulcanized rubber tube into the inflatable silicone core mold, seal the two ends with flanges, and fill the core mold with compressed air to 0.5-0.8MPa to expand the unvulcanized rubber tube to fit the outer mold cavity. The pressure holding time is ≥20min.

[0015] S3 seamless liner forming: After pre-pressurization, the unvulcanized rubber tube is heated to 130-150℃ for vulcanization and shaping. After vulcanization and shaping, it is cooled. After complete cooling, the air pressure is released and the core mold is removed to obtain a seamless liner.

[0016] S4 liner surface functionalization: Use a toothed roller to roll out staggered spiral microgrooves on the seamless liner surface. The spiral microgrooves are 0.5-1mm wide and 0.1-0.3mm deep to increase the resin anchoring area.

[0017] S5 interface adhesive coating: brush-coat epoxy-nitrile composite interface adhesive with a thickness of 50-100 μm;

[0018] S6 prepreg or wet layup: Use carbon fiber / epoxy resin prepreg or wet layup, with a fiber volume fraction of 50%-55%, and reinforcement layers laid in some places;

[0019] S7 curing: Curing at 25-80℃ for 12-48h;

[0020] S8 post-processing: After pressure relief, a composite gas cylinder consisting of a seamless liner, an interface adhesive layer, and a carbon fiber layer is formed.

[0021] In step S4, the pitch of the spiral microgrooves on the surface of the seamless inner liner is 10-20 mm, and the molding depth accuracy is ±0.02 mm.

[0022] The epoxy-nitrile composite interface adhesive applied by brush in step S5 is compounded with epoxy resin, silane coupling agent and nitrile rubber in a mass ratio of 8:0.5:1.5.

[0023] In step S8, the thickness of the carbon fiber layer of the gas storage cylinder is 1-3 mm.

[0024] The carbon fiber / epoxy resin prepreg in the S6 step includes the following steps: first, the carbon fiber fabric is cut into strips and cross-laid in the directions of ±45° and 90°. After each layer is laid, a wet epoxy resin is evenly coated with a scraper. The viscosity of the wet epoxy resin is 800-1200cps, and 2% defoaming agent is added. During the laying process, 0.1-0.3MPa air pressure is filled into the seamless liner to maintain the roundness of the seamless liner and reduce wrinkles.

[0025] The S7 curing step is divided into initial curing and final curing. After laying three layers, the initial curing is performed by pressurizing to -0.05 MPa with a vacuum bag and heating to 50°C for 1 hour to expel bubbles. After all layers are laid, the final curing is performed by heating to 80°C for 4 hours and then post-treating at 60°C for 24 hours.

[0026] Also includes the steps:

[0027] S9 metal interface integration and reinforcement: A threaded metal insert is embedded in the mouth of the composite gas cylinder made in S8. The surface of the insert is processed with a ring-shaped barb structure and bonded to the seamless liner through vulcanization. 3-5 layers of high modulus carbon fiber reinforcement are manually wrapped around the insert in a 0° direction.

[0028] The technical effects that can be achieved by the present invention are:

[0029] 1. Use the internal expansion method to directly form the rubber liner, avoiding complex molds;

[0030] 2. Combining segmented pressurized curing and manual layup processes to achieve low-cost, high-precision manufacturing;

[0031] 3. Improve interface bonding strength through surface microstructure design and resin penetration control;

[0032] 4. No need for inner demoulding, the inner layer is nested with a rubber liner to achieve sealing and prevent leakage;

[0033] 5. The rubber liner is integrally molded and the carbon fiber gas cylinder is made with the liner as support, which can improve the sealing performance and reduce the weight;

[0034] 6. Through spiral micro-groove interface reinforcement, pre-charge expansion compensation and low-cost resin system, heavy truck gas cylinder production can be achieved, while reducing production costs and improving production efficiency;

[0035] 7. Compared with steel cylinders, it has achieved lightweight (core advantage), and the density of carbon fiber composite materials (1.6g / cm 3 ) is only steel (7.8g / cm 3 ) of the gas cylinder. Under the same pressure bearing capacity, the weight of the gas cylinder can be reduced by 50% to 70%;

[0036] 8. Compared with traditional steel cylinders for heavy trucks, the carbon fiber layer isolates the environmental media, and the rubber liner provides an airtight barrier, completely eliminating the risk of rust. It is expected to adapt to highly corrosive working conditions (ports, mining areas, and cold regions). The service life is expected to be extended from 5 to 8 years for steel cylinders to more than 15 years, reducing maintenance costs.

[0037] 9. Design freedom and space optimization: Composite materials can realize non-circular cross-section and curved surface special-shaped designs (such as fitting the chassis contour), improving space utilization by more than 20%. They can adapt to the battery layout requirements of the electrified chassis and facilitate the modular design of multi-cylinder integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0039] Figure 1 This is a schematic diagram of a gas cylinder forming device using the internal expansion method of the present invention;

[0040] Figure 2 This is a schematic diagram of the principle of manual laying and internal expansion assisted shaping.

[0041] Description of reference numerals:

[0042] 1. Gas cylinder; 2. Inflating connector; 3. Outer mold lower mold; 4. Outer mold upper mold; 5. Outer mold right mold; 6. Outer mold left mold; 11. Core mold; 12. Plug. DETAILED DESCRIPTION

[0043] The present invention will be further described in detail below with reference to the accompanying drawings.

[0044] See Figures 1 to 2 .

[0045] A method for manufacturing an integrated rubber liner carbon fiber composite gas storage cylinder comprises the following steps:

[0046] S1. Rubber liner prefabrication: using styrene-butadiene rubber, natural rubber, hydrogenated nitrile rubber, or fluororubber to form an unvulcanized rubber tube blank by rotational molding or compression molding. The present invention uses the above rubber materials to make the unvulcanized rubber tube blank, which has a low cost;

[0047] S2 Pre-pressurization of liner: Insert the unvulcanized rubber tube into the inflatable silicone core mold 11, seal the two ends with flanges, and fill the core mold 11 with compressed air to 0.5-0.8MPa to expand the unvulcanized rubber tube to fit the outer mold cavity. The pressure holding time is ≥20min;

[0048] S3 seamless liner forming: the unvulcanized rubber tube blank after pressurization is heated to 130-150°C for vulcanization and shaping. After vulcanization and shaping, it is cooled. After complete cooling, the air pressure is released and the core mold 11 is removed to obtain a seamless liner;

[0049] S4 liner surface functionalization: Use a toothed roller to roll out staggered spiral microgrooves on the seamless liner surface. The spiral microgrooves are 0.5-1mm wide and 0.1-0.3mm deep to increase the resin anchoring area.

[0050] Specifically, the pitch of the spiral micro-grooves on the surface of the seamless liner is 10-20 mm, the molding depth accuracy is ±0.02 mm, and the surface spiral micro-grooves are molded. As an optimal method, the groove depth is 0.2 mm (depth error ±0.02 mm), the specific surface area is increased by 200%, and the interface mechanical locking strength is increased by about 50%;

[0051] S5 interface adhesive coating: brush-coat epoxy-nitrile composite interface adhesive with a thickness of 50-100 μm;

[0052] Specifically, the brush-coated epoxy-nitrile composite interface adhesive is compounded with epoxy resin, silane coupling agent and nitrile rubber in a mass ratio of 8:0.5:1.5.

[0053] S6 prepreg or wet layup: Use carbon fiber / epoxy resin prepreg or wet layup, with a fiber volume fraction of 50%-55%, and reinforcement layers laid in some places;

[0054] Specifically, the carbon fiber / epoxy resin prepreg in step S6 includes the following steps: first, the carbon fiber fabric is cut into strips, and the layers are cross-laid in the directions of ±45° and 90°. After each layer is laid, a wet epoxy resin is evenly applied using a scraper. The viscosity of the wet epoxy resin is 800-1200cps, and a 2% defoamer is added. During the laying process, an air pressure of 0.1-0.3MPa is filled into the seamless liner to maintain the roundness of the seamless liner and reduce wrinkles.

[0055] S7 curing: Curing at 25-80℃ for 12-48h;

[0056] Curing is divided into initial curing and final curing. After laying three layers, the initial curing is carried out by pressurizing the layer to -0.05 MPa with a vacuum bag and heating it to 50°C for 1 hour to expel bubbles. After all the layers are laid, the final curing is carried out by heating the layer to 80°C for 4 hours and then post-treating it at 60°C for 24 hours. The present invention combines segmented pressurized curing with manual laying process to achieve low-cost and high-precision manufacturing.

[0057] S8 post-processing: After pressure relief, a composite gas cylinder consisting of a seamless liner, an interface adhesive layer, and a carbon fiber layer is formed. The thickness of the carbon fiber layer of the gas cylinder in step S8 is 1-3 mm, and the carbon fiber burst pressure safety factor is ≥ 4 times the working pressure (5 MPa);

[0058] S9 metal interface integration and reinforcement: A threaded metal insert is embedded in the mouth of the composite gas cylinder made in S8. The surface of the insert is processed with a ring-shaped barb structure and bonded to the seamless liner through vulcanization. 3-5 layers of high modulus carbon fiber reinforcement are manually wrapped around the insert in a 0° direction.

[0059] The present invention accurately controls the expansion rate through formula calculation to compensate for fiber shrinkage (the empirical compensation amount is 0.2% to 0.5%); the roundness error after expansion is ≤0.3mm, and the axial curvature is ≤0.5mm / m; in the efficient interface treatment process, the low-viscosity epoxy-nitrile composite interface adhesive (300-500mPa·s) is vacuum-assisted to penetrate into the microgrooves, which can increase the content of 2% to 5% chopped glass fiber (length 0.2-0.5mm) to inhibit cracking; the present invention eliminates the internal demoulding process, shortens the production cycle to 1 / 3 of the traditional process (2-3h for a single piece), the volatilization amount of the resin system is ≤5%, and the VOC emissions comply with the GB 24409-2020 standard.

[0060] The present invention realizes the production of heavy-duty truck gas cylinders through spiral micro-groove interface reinforcement, pre-pressurization expansion compensation and a low-cost resin system, thereby reducing production costs and improving production efficiency. The carbon fiber gas cylinder is made by one-piece molding with a rubber liner as support, which can improve the sealing performance and reduce the weight. The total mass of the gas cylinder of the present invention is reduced by 60% to 70% compared with that of metal gas cylinders, the working pressure cycle range is 0.5 to 1.5 MPa, and the fatigue life is predicted to be ≥5000 times.

[0061] The present invention forms a seamless rubber liner through an internal expansion method. When manufacturing a gas cylinder 1, the mold is mainly composed of an outer mold lower mold 3, an outer mold upper mold 4, an outer mold right mold 5, and an outer mold left mold 6, which avoids complex molds; the gas cylinder 1 is provided with two inflation joints 2, one of which is sealed by a plug 12, and high-pressure gas is filled into the inflation joint 2 not provided with the plug 12. A core mold 11 is provided in the gas cylinder 1, and the injection of high-pressure gas causes the core mold 11 to open; anchoring microgrooves are machined on the surface of the liner and a transition layer is coated; when manually laying carbon fiber fabrics, auxiliary air pressure is applied to the inside of the liner to maintain the shape; the interface bonding strength is improved through surface microstructure design and resin penetration control; and segmented vacuum pressurization curing is used to eliminate interlayer defects.

Claims

1. A method for manufacturing an integrated rubber liner carbon fiber composite gas storage cylinder, characterized in that: The following steps are involved: S1 rubber liner prefabrication: using styrene-butadiene rubber or natural rubber or hydrogenated nitrile rubber or fluororubber to form unvulcanized rubber tube blanks by rotational molding or compression molding; S2 liner pre-pressurization: insert the unvulcanized rubber tube into the inflatable silicone core mold (11), seal the two ends through flanges, and fill the core mold (11) with compressed air to 0.5-0.8MPa, so that the unvulcanized rubber tube expands to fit the outer mold cavity, and the pressure holding time is ≥20min; S3 seamless liner forming: heating the unvulcanized rubber tube blank after pressurization to 130-150°C for vulcanization and shaping, cooling it after vulcanization and shaping, releasing the air pressure after complete cooling and taking out the core mold (11) to obtain a seamless liner; S4 liner surface functionalization: Use a toothed roller to roll out staggered spiral microgrooves on the seamless liner surface. The spiral microgrooves are 0.5-1mm wide and 0.1-0.3mm deep to increase the resin anchoring area. S5 interface adhesive coating: brush-coat epoxy-nitrile composite interface adhesive with a thickness of 50-100 μm; S6 prepreg or wet layup: Use carbon fiber / epoxy resin prepreg or wet layup, with a fiber volume fraction of 50%-55%, and reinforcement layers laid in some places; S7 curing: Curing at 25-80℃ for 12-48h; S8 post-processing: After pressure relief, a composite gas cylinder consisting of a seamless liner, an interface adhesive layer, and a carbon fiber layer is formed.

2. The method for manufacturing a one-piece rubber liner carbon fiber composite gas cylinder according to claim 1, characterized in that: In step S4, the pitch of the spiral microgrooves on the surface of the seamless inner liner is 10-20 mm, and the molding depth accuracy is ±0.02 mm.

3. The method for manufacturing an integrated rubber liner carbon fiber composite gas cylinder according to claim 1, characterized in that: The epoxy-nitrile composite interface adhesive applied by brush in step S5 is compounded with epoxy resin, silane coupling agent and nitrile rubber in a mass ratio of 8:0.5:1.

5.

4. The method for manufacturing a one-piece rubber liner carbon fiber composite gas cylinder according to claim 1, characterized in that: In step S8, the thickness of the carbon fiber layer of the gas storage cylinder is 1-3 mm.

5. The method for manufacturing an integrated rubber liner carbon fiber composite gas storage cylinder according to claim 1, characterized in that: The carbon fiber / epoxy resin prepreg in the S6 step includes the following steps: first, the carbon fiber fabric is cut into strips and cross-laid in the directions of ±45° and 90°. After each layer is laid, a wet epoxy resin is evenly coated with a scraper. The viscosity of the wet epoxy resin is 800-1200cps, and 2% defoaming agent is added. During the laying process, 0.1-0.3MPa air pressure is filled into the seamless liner to maintain the roundness of the seamless liner and reduce wrinkles.

6. The method for manufacturing an integrated rubber liner carbon fiber composite gas storage cylinder according to claim 1 or 5, characterized in that: The S7 curing step is divided into initial curing and final curing. After laying three layers, the initial curing is performed by pressurizing to -0.05 MPa with a vacuum bag and heating to 50°C for 1 hour to expel bubbles. After all layers are laid, the final curing is performed by heating to 80°C for 4 hours and then post-treating at 60°C for 24 hours.

7. The method for manufacturing an integrated rubber liner carbon fiber composite gas storage cylinder according to claim 1, characterized in that: Also includes the steps: S9 metal interface integration and reinforcement: A threaded metal insert is embedded in the mouth of the composite gas cylinder made in S8. The insert surface is processed with a circular barb structure and bonded to the seamless liner through vulcanization. Hand-wrap 3-5 layers of high modulus carbon fiber reinforcement around the insert in a 0° direction.

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