High-pressure gas cylinder applied to liquid helium environment and processing method of high-pressure gas cylinder

Abstract

The invention discloses a high-pressure gas cylinder applied to a liquid helium environment and a machining method of the high-pressure gas cylinder, and relates to the technical field of high-pressure containers. A high-pressure gas cylinder applied to a liquid helium environment comprises a high-pressure gas cylinder body and a coating layer coating the outer surface of the high-pressure gas cylinder body, the shell wall of the high-pressure gas cylinder body sequentially comprises a metal lining cylinder and a composite material layer from inside to outside, and the coating layer and the composite material layer are bonded through low-temperature epoxy glue. The metal lining bottle is formed by mixing alloy metal powder and a solid-phase binding agent through 3D printing. Therefore, the high-pressure gas cylinder has higher strength and pressure resistance, the consumption of raw materials is reduced, the processing period is short, the processing technology is simplified, the manufacturing cost is lower, and the high-pressure gas cylinder has better overall stability and safety.

Description

Technical Field

[0001] The present application relates to a high-pressure gas cylinder for use in a liquid helium environment and a processing method thereof, and belongs to the technical field of high-pressure containers. Background Art

[0002] High-pressure gas cylinders are containers for storing compressed gas, which are widely used in various fields, especially in scientific research and industrial applications under liquid helium and liquid nitrogen environments. Usually, the processing of gas cylinders is realized by stamping, heat treatment, welding, machining and other process methods. The welding forming technology is to split the high-pressure gas cylinder to be manufactured into several main parts and components, and then weld these parts together to form a high-pressure gas cylinder. On the one hand, this method has a long production cycle and is accompanied by serious material waste during the processing and manufacturing process; on the other hand, welding technology is difficult to control as a special processing method, and the intersection of the weld and the substrate will cause stress concentration, resulting in the pressure bearing capacity of the entire welded part being lower than the pressure bearing capacity of the substrate, which to a certain extent limits the improvement of pressure vessel professional technology. There are also problems such as the pollution of materials by harmful substances in unwelded and heat treatment and the amount of metal cutting in machining, which leads to high manufacturing costs. Summary of the invention

[0003] In order to solve the above problems, the present application proposes a high-pressure gas cylinder for use in a liquid helium environment and a processing method thereof, thereby obtaining a high-pressure gas cylinder with a simple and fast manufacturing process and a strong pressure-bearing capacity.

[0004] The present invention provides the following scheme:

[0005] A high-pressure gas cylinder for use in a liquid helium environment, the high-pressure gas cylinder being used in a liquid helium or liquid nitrogen environment, comprising a high-pressure gas cylinder body and a coating layer coated on the outer surface of the high-pressure gas cylinder body, the shell wall of the high-pressure gas cylinder body comprising a metal liner bottle and a composite material layer from the inside to the outside, the coating layer and the composite material layer being bonded by low-temperature epoxy adhesive, and the metal liner bottle being formed by mixing alloy metal powder and a solid binder through 3D printing.

[0006] Optionally, the solid phase binder is BJM3DP binder.

[0007] Optionally, the BJM3DP binder is at least one of sodium citrate, tartrate, succinate or sodium ascorbate.

[0008] Optionally, the alloy metal powder is composed of powders of alloys of two or more of copper, iron, aluminum, titanium, magnesium and silicon.

[0009] Preferably, the metal lined bottle is formed by high temperature bonding of AL6061 metal powder and BJM3DP adhesive.

[0010] Preferably, the metal lined bottle comprises a bottle body in the middle, an air inlet bottle mouth and a bottle bottom respectively arranged at two ends of the bottle body, and the air inlet bottle mouth and the bottle body are transitioned by a bottle shoulder arc.

[0011] Preferably, the bottle bottom is any one of an ellipsoidal shape, a disc shape or a hemispherical shape.

[0012] Preferably, the thickness of the bottle bottom increases uniformly and gradually from 5-8 mm at the edge to 10-20 mm at the center of the bottom cover;

[0013] The inner surface roughness of the bottle body is less than Ra0.8 μm, and the outer surface roughness of the bottle body is less than Ra3.2 μm;

[0014] The overall straightness of the bottle body is not greater than 0.3 mm / m;

[0015] The tolerance of the wall thickness of the bottle body is less than or equal to ±0.1 mm;

[0016] The local straightness of any straight line segment of the bottle body is not greater than 0.3mm / 300mm;

[0017] The overall straightness of the bottle body is not greater than 2 mm / full length;

[0018] The roundness of any position of the bottle body is not greater than 0.3 mm;

[0019] Preferably, the rated pressure of the metal lined bottle is 35-70Mpa.

[0020] According to another aspect of the present application, a method for processing a high-pressure gas cylinder is provided, wherein the manufacturing of the metal-lined cylinder comprises the following steps:

[0021] (1) According to the calculation formula:

[0022]

[0023] Calculate the wall thickness parameter δ of each section of the mouth, shoulder, body and bottom of the metal lined bottle under the design pressure;

[0024] δ: Design wall thickness, i.e. the minimum wall thickness that can withstand the design pressure;

[0025] n: safety factor, which is a design parameter and is derived from usage requirements;

[0026] p: design working pressure;

[0027] D: Calculate the diameter of the pressure-bearing section;

[0028] σ: allowable stress of material;

[0029] K: 3D printing coefficient. The final value of the 3D printing coefficient K is between 0.4 and 2.5. Optionally, the final value of the 3D printing coefficient K is between 0.4 and 2.3.

[0030] (2) according to the wall thickness parameter δ of each section obtained in step (1), a three-dimensional solid model of the high-pressure gas cylinder is designed using three-dimensional modeling software, and then the three-dimensional model is sliced ​​and layered using slicing software to obtain contour data of each cross section, and a laser selective melting molding device is used to mold the bottle body according to the contour data to obtain a bottle body;

[0031] (3) performing subsequent finishing processing on the bottle body formed in step (2).

[0032] Preferably, the 3D printing coefficient of the mouth of the metal lined bottle is:

[0033]

[0034] Preferably, the 3D printing coefficient of the body of the metal lined bottle is:

[0035]

[0036] Preferably, the 3D printing coefficient of the bottom of the metal-lined bottle is:

[0037]

[0038] Preferably, the composite material layer is wrapped around the outside of the metal lined bottle and subjected to self-tightening treatment and adhesive curing treatment.

[0039] The beneficial effects of this application include but are not limited to:

[0040] 1. The present application provides a high-pressure gas cylinder, in which the main body of the high-pressure gas cylinder adopts the structure of a metal liner bottle and a composite material layer, which can provide good rigidity and strength while having a light weight. The metal liner bottle is made of AL6061 metal powder and BJM3DP adhesive bonded at high temperature, and has high strength and corrosion resistance. It can be safely used in liquid helium or liquid nitrogen environments. The composite material layer is coated on the outside of the metal liner bottle, which can increase the wear resistance and corrosion resistance of the gas cylinder, and at the same time provide an additional protective layer to extend the service life of the gas cylinder.

[0041] 2. The high-pressure gas cylinder provided by the present application has a wall thickness and shape that has been calculated and optimized to withstand the design pressure, and has high straightness and roundness to ensure the sealing and stability of the gas cylinder. The control of the roughness of the inner and outer surfaces of the bottle can improve the sealing performance of the gas cylinder and reduce the possibility of gas leakage. The roughness of the inner surface is less than Ra0.8μm, which can ensure that the contact area between the gas and the bottle wall is minimized and reduce gas penetration. The roughness of the outer surface is less than Ra3.2μm, which can reduce the adhesion of dust and dirt and keep the bottle clean.

[0042] 3. The bottom of the high-pressure gas cylinder provided by the present application gradually thickens from the edge to the center, which can improve the structural strength of the bottom, increase the pressure resistance of the bottom, and reduce the risk of deformation or rupture of the bottom. This is particularly important for high-pressure gas cylinders because high-pressure gas will exert a greater pressure on the bottom of the bottle.

[0043] 4. The manufacturing process of a high-pressure gas cylinder provided in this application adopts 3D printing technology to manufacture metal-lined bottles, which can realize the manufacturing of complex shapes and precise dimensions, and improve production efficiency and product quality.

[0044] 5. The manufacturing process of a high-pressure gas cylinder provided in the present application has a simple and easy processing method, and can quickly manufacture a high-pressure gas cylinder that meets the design requirements, and can perform subsequent fine processing as needed to improve the surface quality and performance of the gas cylinder. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0046] Figure 1 A schematic flow chart of the steps of a method for manufacturing a high-pressure gas cylinder provided in an embodiment of the present application. DETAILED DESCRIPTION

[0047] In order to more clearly illustrate the overall concept of the present application, a detailed description is given below in an illustrative manner in conjunction with the accompanying drawings.

[0048] In order to more clearly understand the above-mentioned purposes, features and advantages of the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0049] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited to the specific embodiments disclosed below.

[0050] In addition, in the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0051] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0052] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0053] In the present application, unless otherwise clearly specified and limited, a first feature "above" or "below" a second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples.

[0054] Example 1

[0055] The embodiment of the present application discloses a manufacturing process of a metal-lined cylinder of a high-pressure gas cylinder, comprising the following steps:

[0056] According to the calculation formula:

[0057]

[0058] Calculate the wall thickness parameter δ of the mouth, shoulder, body and bottom of the metal-lined bottle under the design pressure

[0059] δ: Design wall thickness, i.e. the minimum wall thickness that can withstand the design pressure;

[0060] n: safety factor, which is a design parameter and is derived from usage requirements;

[0061] p: design working pressure;

[0062] D: Calculate the diameter of the pressure-bearing section;

[0063] σ: allowable stress of material;

[0064] K: 3D printing coefficient. The final value of 3D printing coefficient K is between 0.5 and 2.5.

[0065] In the casting process of this high-pressure gas cylinder, the 3D printing coefficients of spheres, cylinders and cones are mainly involved. Considering the characteristics of laser selective melting technology, such as laser selective melting of inclined structures greater than 45 degrees, which is basically unattainable or costly, shape parameters are set according to engineering experience and assigned to the 3D printing coefficient; in addition, the formula also takes into account the hot melting of metal powder. Laser selective melting technology is different from traditional casting. Its characteristics require that the comprehensive influence of heat on materials of different materials and structures must be fully considered during structural design calculations. Therefore, according to engineering experience, the influence of metal hot melting is also assigned to the 3D printing coefficient. The final value of the 3D printing coefficient K is between 0.5 and 2.5. The empirical formula for the K value derived from theoretical and engineering test data is as follows:

[0066] The 3D printing coefficient of the mouth of the metal lined bottle is:

[0067]

[0068] The 3D printing coefficient of the body of the metal lined bottle is:

[0069]

[0070] The 3D printing coefficient of the bottom of the metal lined bottle is:

[0071]

[0072] In the casting process of the high-pressure gas cylinder, the 3D printing coefficients of the bottle mouth, bottle shoulder, bottle body and bottle bottom are mainly involved. Taking into account the characteristic requirements of the laser selective melting technology, such as the laser selective melting of the inclined surface structure greater than 45 degrees is basically impossible to achieve or the cost is high, so the shape parameters are set according to engineering experience and assigned to the 3D printing coefficient; in addition, the formula also takes into account the hot melting of metal powder. The laser selective melting technology is different from traditional casting. Its characteristics require that the comprehensive influence of heat of different materials and structures on the material must be fully considered in the structural design calculation. Therefore, according to engineering experience, the influence of metal hot melting is also assigned to the 3D printing coefficient.

[0073] According to the above formula, the design wall thickness parameter δ required for each section of the high-pressure gas cylinder under the design pressure is calculated, and the wall thickness parameter of the high-pressure gas cylinder is input into the laser selective melting molding equipment to form the bottle body. After the bottle body is produced, the bottle body is subsequently fine-processed using existing conventional technology to improve the quality and processing accuracy of the bottle body. The process mainly includes stress relief heat treatment of the bottle body, mechanical processing of features such as threads, physical and chemical testing of microstructures, vacuum aging treatment, internal and external surface treatment, overall non-destructive testing, and finally final testing according to the design input. In other embodiments, other methods can also be used to fine-process the bottle body.

[0074] Finally, the performance of the manufactured high-pressure gas cylinder was tested. In this embodiment, the casting and subsequent performance test of the high-pressure gas cylinder with a design pressure of 35MPa and 70MPa were carried out. The materials used in the casting were all AL6061 metal powder, wherein the AL6061 metal powder included alloy metal powders of 97.2% aluminum, 1.0% magnesium, 0.6% silicon, 0.2% iron, 0.4% copper, 0.08% manganese, 0.06% titanium, 0.11% manganese, and 0.08% zinc. r is the radius of the inner diameter of the bottle mouth, and its experimental data are shown in Table 1 below:

[0075] Table 1

[0076]

[0077]

[0078] In summary, the high-pressure gas cylinder manufactured by laser selective melting molding technology and subsequent finishing technology has the entire bottle body formed in one piece, with fast production speed and high material utilization rate. It can be input remotely and can realize the molding and processing of thin-walled high-pressure gas cylinders with a working pressure of 35-70MPa. In addition, the finishing technology is used to finish the bottle body to ensure the manufacturing quality of the high-pressure gas cylinder.

[0079] Example 2

[0080] Based on Example 1, the main difference is that the composite material in the composite material layer is a composite fiber, and the preparation method of the composite fiber includes the following steps: melt blending carbon fiber, styrene-butadiene-styrene block copolymer and lignin at a mass ratio of 1:3:2 at a temperature of 150°C, then adding acrylonitrile copolymer to continue the reaction, and finally adding N,N-dimethylformamide to obtain a spinning solution, and spinning to obtain the composite fiber. Among them, the mass ratio of acrylonitrile copolymer to lignin is 2:1.

[0081] The composite material layer prepared in Example 2 was applied to the metal liner, and the performance of the gas cylinder was tested, as shown in Table 2.

[0082] Table 2

[0083]

[0084] As shown in Table 2, by wrapping the composite material layer around the bottle mouth, bottle shoulder and bottle body respectively, the compatibility of the composite material layer with the metal liner can be improved, while the strength of the high-pressure gas cylinder is improved and the safety factor of the high-pressure gas cylinder is improved.

[0085] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0086] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A high-pressure gas cylinder for use in a liquid helium environment, characterized in that: It includes a high-pressure gas cylinder body and a coating layer coated on the outer surface of the high-pressure gas cylinder body. The shell wall of the high-pressure gas cylinder body includes a metal liner bottle and a composite material layer from the inside to the outside. The coating layer and the composite material layer are bonded by low-temperature epoxy adhesive. The metal liner bottle is made of a mixture of alloy metal powder and solid binder through 3D printing.

2. The high-pressure gas cylinder for use in a liquid helium environment as claimed in claim 1, characterized in that: The alloy metal powder is powder of two or more alloys of copper, iron, aluminum and titanium.

3. The high-pressure gas cylinder for use in a liquid helium environment as claimed in claim 1, characterized in that: The solid phase binder is BJM3DP binder.

4. The high-pressure gas cylinder according to claim 1, characterized in that: The metal lined bottle comprises a bottle body in the middle, an air inlet bottle mouth and a bottle bottom respectively arranged at two ends of the bottle body, and the air inlet bottle mouth and the bottle body are transitioned by a bottle shoulder arc.

5. The high-pressure gas cylinder according to claim 4, characterized in that: The bottle bottom is any one of an ellipsoidal shape, a dish shape or a hemispherical shape.

6. The high-pressure gas cylinder according to claim 4, characterized in that: The thickness of the bottle bottom increases gradually from 5-8 mm at the edge to 10-20 mm at the center of the bottom cover; The inner surface roughness of the bottle body is less than Ra0.8 μm, and the outer surface roughness of the bottle body is less than Ra3.2 μm; The overall straightness of the bottle body is not greater than 0.3 mm / m; The tolerance of the wall thickness of the bottle body is less than or equal to ±0.1 mm; The local straightness of any straight line segment of the bottle body is not greater than 0.3mm / 300mm; The overall straightness of the bottle body is not greater than 2 mm / full length; The roundness of any position of the bottle body is no more than 0.3 mm.

7. The high-pressure gas cylinder according to claim 1, characterized in that: The rated pressure of the metal lined bottle is 35-70Mpa.

8. A method for processing a high-pressure gas cylinder for use in a liquid helium environment as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: (1) According to the calculation formula: Calculate the wall thickness parameter δ of each section of the mouth, shoulder, body and bottom of the metal lined bottle under the design pressure; δ: Design wall thickness, i.e. the minimum wall thickness that can withstand the design pressure; n: safety factor, which is a design parameter and is derived from usage requirements; p: design working pressure; D: Calculate the diameter of the pressure-bearing section; σ: allowable stress of material; K: 3D printing coefficient. The final value of 3D printing coefficient K is between 0.4 and 2.

3. (2) according to the wall thickness parameters δ of the bottle mouth, bottle shoulder, bottle body and bottle bottom obtained in step (1), a three-dimensional solid model of the high-pressure gas cylinder is designed using three-dimensional modeling software, and then the three-dimensional model is sliced ​​and layered using slicing software to obtain contour data of each cross section, and a laser selective melting molding device is used to mold the bottle body according to the contour data to obtain a bottle body; (3) performing subsequent finishing processing on the inner liner bottle body formed in step (2).

9. A method for processing a high-pressure gas cylinder as claimed in claim 8, characterized in that: The composite material layer is wound around the outside of the metal lined bottle and subjected to self-tightening treatment and adhesive curing treatment.

Images