Shoulder reinforcing method for composite material fully-wound gas cylinder

Abstract

The invention discloses a shoulder reinforcing method of a composite material fully-wound gas cylinder, which comprises the following steps: designing a shoulder reinforcing sheet winding die according to the shape of an end socket of a gas cylinder liner, the shoulder reinforcing sheet winding die being equivalent to a structure formed by splicing two end sockets at the shoulder; determining a forming area range of the shoulder reinforcing forming sheet; placing the shoulder reinforcing sheet winding mold on a winding machine, and carrying out winding molding by using prepreg yarns according to the determined molding area range to obtain a shoulder reinforcing molding sheet; curing the shoulder reinforcing molded sheet and then symmetrically segmenting the shoulder reinforcing molded sheet from the central position to obtain a shoulder reinforcing sheet; the shoulder reinforcing sheet is attached to the shoulder position of the end socket of the gas cylinder inner container; and winding and forming the gas cylinder liner pasted with the shoulder reinforcing sheet by using the prepreg to obtain the composite material fully-wound gas cylinder. According to the shoulder reinforcing method, the weak position of the shoulder can be accurately reinforced, the edge stress near the shoulder is reduced, the structural reliability of a product is improved, additional equipment is not needed, and the forming efficiency is high.

Description

Technical Field

[0001] The present invention relates to the technical field of fully wound gas cylinders, and particularly to a method for reinforcing the shoulder of a composite material fully wound gas cylinder. Background Art

[0002] Due to its excellent properties such as light weight and high strength, composite material fully wound gas cylinders have broad application prospects in many fields such as aerospace, automotive, and energy. A composite material fully wound gas cylinder mainly consists of an inner liner and a winding layer. The inner liner is usually made of metal or plastic materials and serves to seal the gas; the winding layer is formed by winding high-strength fiber materials (such as carbon fiber, glass fiber, etc.) through a resin matrix and undertakes the main load-bearing function of the gas cylinder. The shoulder of the gas cylinder is the transition area between the inner liner and the winding layer, with a complex geometric shape and uneven stress distribution, making it one of the weakest parts in the entire gas cylinder structure. The structural weakness at the transition position of the gas cylinder shoulder has always been a key bottleneck restricting its performance improvement. Although traditional reinforcement methods have certain effects, there are many deficiencies, such as material waste, poor deformation coordination, low laying efficiency, and poor economic benefits. For example:

[0003] (1) Large-angle spiral winding reinforcement method

[0004] Principle: During the winding process of the gas cylinder, large-angle spiral layering is used to reinforce the shoulder. This method improves the load-bearing capacity of this area by increasing the winding density of the fibers at the shoulder.

[0005] Limitations:

[0006] Material waste: Due to the continuity of the winding process, the fiber yarn bundle not only winds around the shoulder but also has to wind around the barrel section, resulting in a large consumption of the reinforcement layer material;

[0007] Poor deformation coordination: The strength of the upper and lower barrel sections and the head at the shoulder increases simultaneously, but the deformation of the gas cylinder in this area is still difficult to coordinate, and new stress concentration points are likely to occur;

[0008] Complex process: Precise control of the winding angle and tension is required, which has high technical requirements for equipment and operators, increasing the production cost and difficulty.

[0009] (2) Prepreg tape laying reinforcement method

[0010] Principle: Prepreg tape is used to lay the head, and local reinforcement of the shoulder is carried out through the high modulus and high strength characteristics of the prepreg tape.

[0011] Limitations:

[0012] Low laying efficiency: The laying process of the prepreg tape needs to be carried out layer by layer, and each layer requires precise alignment and compaction, with complex operations and low efficiency;

[0013] High equipment requirements: Large-scale production requires additional laying equipment and related supporting facilities, increasing equipment investment and maintenance costs;

[0014] Poor economic efficiency: The cost of prepreg tape materials is relatively high, and the material loss during the laying process is relatively large, resulting in low overall economic efficiency.

[0015] Therefore, it is urgent to explore a new reinforcement method that is more efficient, economical and can effectively solve the problem of weak shoulders. Summary of the Invention

[0016] To solve the above technical problems, the purpose of the present invention is to provide a shoulder reinforcement method for a composite material fully wound gas cylinder. This shoulder reinforcement method can accurately reinforce the weak positions of the shoulders, reduce the edge stress near the shoulders, improve the structural reliability of the product, and does not require additional equipment, and has high forming efficiency.

[0017] To achieve the above technical purposes and technical effects, the present invention is realized through the following technical solutions:

[0018] A shoulder reinforcement method for a composite material fully wound gas cylinder, comprising the following steps:

[0019] S1, Prepare a winding mold for the shoulder reinforcement patch

[0020] Design a winding mold for the shoulder reinforcement patch according to the shape of the head of the gas cylinder inner liner. This winding mold for the shoulder reinforcement patch is equivalent to the structure after splicing two heads at the shoulders;

[0021] S2, Wind and prepare the shoulder reinforcement patch

[0022] Determine the forming area range of the shoulder reinforcement forming patch. The forming area range covers an area with a certain width on both sides of the longitudinal center of the shoulder reinforcement patch winding mold;

[0023] Place the shoulder reinforcement patch winding mold on the winding machine, and use prepreg yarn to wind and form according to the determined forming area range of the shoulder reinforcement patch to obtain a shoulder reinforcement forming patch; symmetrically cut the shoulder reinforcement forming patch from the longitudinal center position after curing to obtain a shoulder reinforcement patch;

[0024] S3, Mount the shoulder reinforcement patch

[0025] Mount the shoulder reinforcement patch on the head shoulder position of the gas cylinder inner liner;

[0026] S4, Wind and form the gas cylinder

[0027] Wind and form the gas cylinder inner liner with the shoulder reinforcement patch according to the designed winding line pattern rule using prepreg to obtain a composite material fully wound gas cylinder.

[0028] Furthermore, the winding mold for the shoulder reinforcement patch is made of metal material.

[0029] Furthermore, a slot is provided at the longitudinal center of the winding mold for the shoulder reinforcement patch.

[0030] Furthermore, in step S2, the shoulder reinforcement forming patch is symmetrically divided by sawing, and the dividing position corresponds to the position of the slot.

[0031] Furthermore, in step S2, the forming area range is determined according to the radius and wall thickness of the gas cylinder.

[0032] Furthermore, the unilateral width from the longitudinal center of the winding mold for the shoulder reinforcement patch is wherein, K is an empirical coefficient, taken from 1.5 - 2.5, R is the radius of the gas cylinder, and δ is the wall thickness of the gas cylinder.

[0033] Furthermore, in step S3, after the shoulder reinforcement patch is attached, a rubber hammer is used to gently tap the shoulder reinforcement patch along the circumferential direction of the inner liner of the gas cylinder multiple times, so that there is no gap between the shoulder reinforcement patch and the inner liner of the gas cylinder.

[0034] Furthermore, the prepreg yarn in step S2 and the prepreg in step S4 use the same fiber and resin.

[0035] The beneficial effects of the present invention are as follows:

[0036] (1) The present invention designs the winding mold for the shoulder reinforcement patch according to the head shape of the inner liner of the gas cylinder. This mold is equivalent to the structure after splicing two heads at the shoulder, so that the shape of the shoulder reinforcement patch made by using this mold highly coincides with the actual shape of the shoulder of the gas cylinder. In this way, when attaching the reinforcement patch, it can accurately cover the weak area of the shoulder, ensure that the reinforcement material plays a role in the most needed position, effectively improve the pertinence and accuracy of reinforcement, greatly reduce the edge stress near the shoulder, and improve the structural reliability of the product.

[0037] (2) The size of the shoulder reinforcement patch designed by the present invention is adapted to the actual structural parameters of the gas cylinder, which can ensure the reasonable distribution of the reinforcement patch on the shoulder of the gas cylinder. It will neither be too small to effectively cover the weak area nor be too large to cause material waste or generate new stress concentration points, thus realizing precise reinforcement of the shoulder of the gas cylinder.

[0038] (3) The present invention places the winding mold for the shoulder reinforcement patch on the winding machine, and uses the prepreg yarn to wind and form according to the determined forming area range of the shoulder reinforcement patch to obtain the shoulder reinforcement forming patch, and then obtain the shoulder reinforcement patch. When making the shoulder reinforcement forming patch, the continuity of the winding process enables the prepreg yarn to be quickly and evenly wound on the mold, ensuring the quality and consistency of the shoulder reinforcement patch.

[0039] (4) The present invention strengthens the shoulder by first manufacturing a shoulder reinforcement patch, attaching the shoulder reinforcement patch to the shoulder position of the inner liner, and then performing winding. Compared with the traditional prepreg tape laying reinforcement method and large-angle spiral winding reinforcement method, this method greatly reduces the operation steps and time, improves the efficiency, realizes precise reinforcement, and reduces material waste and stress concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 FIG. is a schematic structural view of a winding mold for a shoulder reinforcement patch of the present invention.

[0041] Figure 2 FIG. is a schematic structural view of a shoulder reinforcement patch of the present invention.

[0042] Figure 3 FIG. is a schematic structural view of a fully wound gas cylinder obtained by the present invention.

[0043] Figure 4 is Figure 3 an enlarged schematic view of part A of the gas cylinder shown.

[0044] In the figures, 1: winding mold for shoulder reinforcement patch, 11: slotted, 2: fully wound composite material gas cylinder, 21: inner liner, 22: shoulder reinforcement patch, 23: gas cylinder winding layer; 3: shoulder reinforcement forming patch. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] The following elaborates in detail on the preferred embodiments of the present invention with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making the scope of protection of the present invention more clearly defined.

[0046] As Figures 1 to 4 shown, a method for strengthening the shoulder of a fully wound composite material gas cylinder includes the following steps:

[0047] S1, Prepare a winding mold for the shoulder reinforcement patch

[0048] Design a winding mold 1 for the shoulder reinforcement patch according to the head shape of the inner liner 21 of the gas cylinder. The final shape of this winding mold 1 for the shoulder reinforcement patch is equivalent to the structure after splicing of two heads at the shoulder, that is, equivalent to a spherical-like structure formed by butt-jointing two heads along the equatorial plane at the maximum diameter (shoulder).

[0049] This winding mold 1 for the shoulder reinforcement patch is made of a metal material. For example, a high-strength metal (such as 45# steel, alloy steel or aluminum alloy) is selected to ensure sufficient rigidity, wear resistance and dimensional stability. The surface of the mold needs to be precision machined (turning / grinding) to the required surface finish (Ra≤1.6μm), and demolding treatment (such as spraying a Teflon coating or using a mold release agent) is considered.

[0050] A slot 11 is provided at the longitudinal center of the shoulder reinforcement winding die 1. The slot must be precisely located on the longitudinal center line (axis of symmetry) of the die. The width of the slot should be slightly larger than the thickness of the subsequent cutting saw blade (for example, if the saw blade is 3 mm thick, the slot width is 3.5 - 4.0 mm) to ensure that the saw blade can pass freely and avoid friction. The core function of the slot is to serve as an accurate cutting guide reference to ensure that the shoulder reinforcement can be perfectly symmetrically divided along the center line after subsequent curing.

[0051] S2. Wind and prepare the shoulder reinforcement

[0052] Determine the forming area range of the shoulder reinforcement forming sheet 3, and the forming area range covers an area with a certain width on both sides of the longitudinal center of the shoulder reinforcement winding die; specifically, this forming area range can be determined according to the radius and wall thickness of the gas cylinder; preferably, the unilateral width from the longitudinal center of the shoulder reinforcement winding die is where K is an empirical coefficient, taken from 1.5 - 2.5, and the specific value needs to be determined through experiments or mature engineering experience according to the material system, design pressure, safety factor, etc. R is the radius of the gas cylinder, and δ is the wall thickness of the gas cylinder. In addition, this forming area range can also be simulated and calculated using software such as ANSYS or ABAQUS. By simulating the stress distribution and force conditions, the optimal forming area range can be determined.

[0053] Place the shoulder reinforcement winding die 1 on the winding machine, and wind and form it using the prepreg yarn according to the determined forming area range of the shoulder reinforcement forming sheet to obtain the shoulder reinforcement forming sheet 3; after curing the shoulder reinforcement forming sheet 3, symmetrically cut it from the center position to obtain the shoulder reinforcement 22.

[0054] The prepreg yarn can be selected from carbon fiber or glass fiber, and is paired with epoxy resin or polyimide resin, etc. During winding, the winding angle is ±55°, the number of prepreg yarn winding layers is 8 layers, and the winding tension is controlled at 30% - 50% of the prepreg yarn strength, generally 50 - 100 N. After winding, place the shoulder reinforcement forming sheet 3 in a curing furnace and cure it at 120 - 150 °C for 2 - 3 hours. The tensile strength of the cured shoulder reinforcement should be ≥1200 MPa. Then symmetrically cut it along the longitudinal center position using a diamond circular saw blade with a rotational speed of 800 - 1200 r / min and a feed speed of 50 - 100 mm / min. The thickness tolerance of the cut shoulder reinforcement is controlled within ±0.5 mm, and the cutting position corresponds to the slot position of the shoulder reinforcement winding die 1.

[0055] S3. Mount the shoulder reinforcement

[0056] Attach the shoulder reinforcement patch 22 to the head shoulder position of the inner liner 21 of the gas cylinder. When attaching, use a laser locator to ensure that the shoulder reinforcement patch is aligned with the head shoulder, with the error controlled within ±1 mm. Use a special adhesive, such as epoxy resin glue, with a bonding strength ≥ 30 MPa, and cure it at 25 °C for 24 hours. After attaching, use a rubber hammer to gently tap the shoulder reinforcement patch 22 along the circumferential direction of the gas cylinder inner liner multiple times. The tapping force is controlled within 5 - 10 N, the distance between tapping points is 30 - 50 mm, and the number of tapping times ≥ 3 times, so that there is no gap between the shoulder reinforcement patch 22 and the inner liner 21. Finally, use ultrasonic testing technology to detect the gap situation and ensure that the gap ≤ 0.1 mm.

[0057] S4, winding and forming of the gas cylinder

[0058] Wind and form the inner liner 21 with the shoulder reinforcement patch 22 using prepreg according to the designed winding line pattern law to form the gas cylinder winding layer 23, and then obtain the composite material fully wound gas cylinder 2. The prepreg in this step uses the same fibers and resin as in step S2, such as carbon fiber T700 and epoxy resin CYD - 128, and the resin content is controlled within 35% - 45%. The winding angle is ±55°, the winding line pattern is alternating spiral and circumferential, the number of prepreg winding layers is 16 layers, and the winding tension is controlled within 100 ± 10 N. After winding, use a segmented curing process for curing, that is, first cure at 80 °C for 1 hour, then cure at 120 °C for 2 hours, and finally cure at 150 °C for 1 hour. After curing, perform surface treatment, such as grinding and painting, to ensure that the surface roughness Ra of the gas cylinder ≤ 1.6 μm and the thickness of the paint layer ≥ 50 μm.

[0059] Example

[0060] Such as Figures 1 to 4 shown in a method for reinforcing the shoulder of a composite material fully wound gas cylinder, including the following steps:

[0061] S1, prepare the shoulder reinforcement patch winding mold

[0062] Design the shoulder reinforcement patch winding mold 1 according to the head shape of the inner liner 21 of a certain model of composite material fully wound gas cylinder. The radius R of the head of this inner liner 21 is 250 mm, and the wall thickness δ is 6 mm. The final shape of this shoulder reinforcement patch winding mold 1 is equivalent to the structure after splicing two heads at the shoulder, that is, equivalent to the spherical - like structure formed after docking two heads along the equatorial plane at the maximum diameter (shoulder).

[0063] This shoulder reinforcement patch winding mold 1 is made of 6061 aluminum alloy, which has good formability and corrosion resistance. The surface of the mold needs to be precision machined (turning / grinding) to the required surface finish (Ra is 0.5 μm).

[0064] A slot 11 is provided at the longitudinal center of the shoulder reinforcement winding die 1. The width of the slot is 5 mm and the depth is 8 mm.

[0065] S2. Winding and preparing the shoulder reinforcement

[0066] Determine the forming area range of the shoulder reinforcement forming piece 3. The forming area range covers the areas on both sides of the longitudinal center of the shoulder reinforcement winding die 1 with a certain width; among them, the unilateral width W from the longitudinal center of the shoulder reinforcement winding die 1 is K is taken as 2.5, That is, the total width of the forming area range of the shoulder reinforcement forming piece is 97×2 = 194 mm.

[0067] Place the shoulder reinforcement winding die 1 on the winding machine, and use the prepreg to wind and form according to the determined forming area range of the shoulder reinforcement forming piece to obtain the shoulder reinforcement forming piece 3.

[0068] Among them, the prepreg is made of carbon fiber T700 and epoxy resin CYD - 128. The winding angle is ±55°, the number of prepreg winding layers is 8 layers, the winding tension is controlled at about 80 N, and this tension is 40% of the prepreg strength. During the winding process, ensure that the prepreg is closely attached to the die without defects such as looseness and wrinkles.

[0069] After winding, put the wound shoulder reinforcement forming piece 3 into the curing furnace and cure it at 130°C for 2.5 hours. After curing, the tensile strength of the reinforcement piece reaches 1250 MPa. Then use a diamond circular saw blade to symmetrically cut the shoulder reinforcement forming piece along the slot position of the shoulder reinforcement winding die at a rotational speed of 1000 r / min and a feed speed of 80 mm / min to obtain two shoulder reinforcement pieces 22, and the width of each shoulder reinforcement piece 22 is 97 mm. The thickness tolerance of the reinforcement piece after cutting is controlled within ±0.5 mm.

[0070] S3. Mounting the shoulder reinforcement

[0071] Mount the shoulder reinforcement piece 22 at the head shoulder position of the inner liner 21; during mounting, use a laser locator to ensure that the shoulder reinforcement piece 22 is aligned with the center line of the head shoulder, and the error is controlled within ±1 mm. Use an epoxy resin adhesive with a bonding strength ≥30 MPa for bonding and cure it at 25°C for 24 hours. After mounting, use a rubber hammer to gently tap the shoulder reinforcement piece 22 along the circumferential direction of the gas cylinder inner liner multiple times. The tapping force is controlled at 8 N, the spacing between tapping points is 40 mm, and the number of tapping times is 5 times to make there be no gap between the shoulder reinforcement piece 22 and the inner liner 21. Finally, use ultrasonic testing technology to detect the gap situation to ensure that the gap ≤0.1 mm.

[0072] S4. Winding and forming of the gas cylinder

[0073] According to the designed winding line pattern rule, use prepreg to wind and form the inner liner 21 with the shoulder reinforcement patch 22 attached, forming the gas cylinder winding layer 23, and then obtaining the composite material fully wound gas cylinder 2. The prepreg in this step uses the same fibers and resin as in step S2. The winding angle is ±55°, the winding line pattern is alternating spiral and circumferential, the number of prepreg winding layers is 16 layers, and the winding tension is controlled at 100 ± 10 N. After winding, a segmented curing process is used for curing, that is, first cure at 80 °C for 1 hour, then cure at 120 °C for 2 hours, and finally cure at 150 °C for 1 hour. After curing, surface treatment such as grinding and painting is carried out to ensure that the surface roughness Ra of the gas cylinder is 1.2 μm and the thickness of the paint layer is 60 μm.

[0074] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to embrace all changes falling within the meaning and scope of the equivalent elements of the claims within the present invention.

[0075] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for reinforcing the shoulder of a fully wound composite gas cylinder, characterized in that It includes the following steps: S1. Prepare a winding mold for the shoulder reinforcement patch Design a winding mold for the shoulder reinforcement patch according to the shape of the head of the gas cylinder inner liner. This winding mold for the shoulder reinforcement patch is equivalent to the structure after splicing two heads at the shoulder; S2. Wind and prepare the shoulder reinforcement patch Determine the forming area range of the shoulder reinforcement forming patch. The forming area range covers the areas with a certain width on both sides of the longitudinal center of the winding mold for the shoulder reinforcement patch; Place the winding mold for the shoulder reinforcement patch on the winding machine, and use the prepreg yarn to wind and form according to the determined forming area range of the shoulder reinforcement patch to obtain the shoulder reinforcement forming patch; symmetrically cut the shoulder reinforcement forming patch from the longitudinal center position after curing to obtain the shoulder reinforcement patch; S3. Mount the shoulder reinforcement patch Mount the shoulder reinforcement patch on the shoulder position of the head of the gas cylinder inner liner; S4. Wind and form the gas cylinder Wind and form the gas cylinder inner liner with the mounted shoulder reinforcement patch according to the designed winding line pattern rule using the prepreg to obtain a fully wound composite gas cylinder.

2. The shoulder reinforcement method of a fully wound gas cylinder made of composite material according to claim 1, characterized in that The winding mold for the shoulder reinforcement patch is made of metal material.

3. A method for reinforcing the shoulder of a fully wound composite gas cylinder according to claim 1, characterized in that, A slot is provided at the longitudinal center of the winding mold for the shoulder reinforcement patch.

4. A method for reinforcing the shoulder of a fully wound composite gas cylinder according to claim 3, characterized in that In step S2, the shoulder reinforcement forming patch is symmetrically cut by sawing, and the cutting position corresponds to the position of the slot.

5. A method for reinforcing the shoulder of a fully wound composite gas cylinder according to claim 1, characterized in that, In step S2, the forming area range is determined according to the radius and wall thickness of the gas cylinder.

6. A method for reinforcing the shoulder of a fully wound composite gas cylinder according to claim 5, characterized in that The unilateral width from the longitudinal center of the shoulder reinforcement wrapping die is where K is an empirical coefficient, taken from 1.5 - 2.5, R is the radius of the gas cylinder, and δ is the wall thickness of the gas cylinder.

7. A method for reinforcing the shoulder of a fully wound composite gas cylinder according to claim 1, characterized in that In step S3, before mounting the shoulder reinforcement patch, a layer of resin is evenly coated on the shoulder position of the head of the gas cylinder inner liner.

8. A method for strengthening the shoulder of a fully wound gas cylinder made of composite materials according to claim 1, characterized in that, In step S3, after mounting the shoulder reinforcement patch, use a rubber hammer to gently tap the shoulder reinforcement patch along the circumferential direction of the gas cylinder inner liner multiple times to make there be no gap between the shoulder reinforcement patch and the gas cylinder inner liner.

9. A method for reinforcing the shoulder of a fully wound composite gas cylinder according to claim 1, characterized in that The prepreg yarn in step S2 and the prepreg in step S4 use the same fiber and resin.

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