Additive manufacturing device and method for liquid hydrogen storage spherical tank

Abstract

The invention relates to a liquid hydrogen storage spherical tank additive manufacturing device and method, in particular to the technical field of additive manufacturing. The additive manufacturing device comprises a multi-axis motion printing system, a digital multifunctional power supply and control system, a printing consumable feeding and control system and a controller. The manufacturing method comprises the steps that a single-phase aluminum-magnesium alloy or invar alloy material serves as a printing material, and according to the printing speed, the wire diameter and the wire feeding speed, the electric arc power of a printing mechanism of the digital multifunctional power source and control system in the additive and subtractive manufacturing process of the liquid hydrogen storage spherical tank is set; adopting a liquid hydrogen storage spherical tank additive manufacturing device to perform additive manufacturing according to the G code path control program corresponding to the inner and outer surfaces of the spherical tank body, and printing to obtain the spherical tank body; according to the method, additive manufacturing of the liquid hydrogen storage tank can be effectively achieved, uniformity and refinement of the internal structure of a printed product and accurate and controllable appearance are achieved, and the method has huge application value.

Description

Technical Field

[0001] The present application relates to the field of additive manufacturing technology, and in particular to an additive manufacturing device and method for a liquid hydrogen storage spherical tank. Background Art

[0002] Hydrogen is an ideal and important available energy source. The volumetric energy storage density of liquid hydrogen can reach 800 times that of gaseous hydrogen. Therefore, it is most ideal to store and transport it in the form of liquid hydrogen. However, the temperature of liquid hydrogen is very low, about -252.87℃, which brings two potential hazards to the materials used in the tanks for storage and transportation. First, low temperature may cause the plastic toughness of the material to drop sharply, resulting in low-temperature embrittlement; second, the strong diffusibility of hydrogen may cause hydrogen-induced brittle fracture of the material. Therefore, the material selection of liquid hydrogen storage tanks must avoid low-temperature embrittlement and hydrogen embrittlement.

[0003] Existing liquid hydrogen storage tanks are usually composed of two layers with a high vacuum layer in the middle. This high vacuum provides extremely high insulation value and is an ideal way to perfectly maintain cryogenic liquids at their temperature; for example, liquid hydrogen with a temperature of -252.9°C, and the double wall can act as a double containment shell; liquid hydrogen storage tanks usually use structural steel / stainless steel as the outer shell, and the shell manufacturing process can usually be summarized as the following steps: (1) Plate cutting: Spherical tanks are usually made of metal plates, and the metal plates are cut into the required size using cutting tools such as plasma cutting machines or laser cutting machines; (2) Shell plate forming: By combining the use of dishing, spinning, progressive forming and other metal processing technologies, the plate is gradually formed into a curved shape to manufacture spherical tank components; (3) Trimming and finishing: After the hemisphere is formed, trimming may be required to remove excess material and reach the final size, and the edges can also be smoothed and finished (4) Forming a hemisphere or prefabricated component: The bent plates are spliced ​​together and fixed with jigs to form the desired shape; (5) Welding and heat treatment: The spliced ​​plates are welded together along their edges to form a hemisphere or prefabricated component and the structure is heat treated to remove stress; (6) Transportation and installation: Each component will be transported to the final location and installed according to the manufacturer's guidelines and industry standards; (7) Welding and post-weld heat treatment: The prefabricated parts are then spliced ​​and welded together along their edges to form a complete sphere, and the structure is heat treated to remove stress; (8) Surface treatment: After welding, the surface is usually treated to remove any defects and prevent corrosion; this may involve processes such as sandblasting, painting or coating; Each step in the above process requires precision and specialized equipment to ensure that the required specifications for strength, quality and dimensional accuracy are met.

[0004] The lining of liquid hydrogen storage tanks can be made of Invar alloy / modified stainless steel and welded using a similar process flow. The lining of large liquid hydrogen tanks is also formed by manually laying Invar alloy sheets and manually welding them. In general, the manufacturing process of liquid hydrogen storage tanks, especially large spherical tanks, is complex, with a long cycle and high cost.

[0005] In view of the above analysis, it is necessary to design a new method for preparing liquid hydrogen storage spherical tanks to solve the above problems. Summary of the invention

[0006] The present application provides an additive manufacturing device and method for a liquid hydrogen storage spherical tank, which is used to solve the problem that the existing liquid hydrogen storage tank preparation is difficult.

[0007] According to a first aspect of the present application, the present application provides an additive manufacturing device for a liquid hydrogen storage spherical tank, comprising: a multi-axis motion printing system, a digital multifunctional power supply and control system, a printing consumables feeding and control system, and a controller;

[0008] The digital multifunctional power supply and control system and the printing consumables feeding and control system are all connected to the multi-axis motion printing system; and the multi-axis motion printing system, the digital multifunctional power supply and control system, and the printing consumables feeding and control system are all electrically connected to the controller to control the preparation of liquid hydrogen storage spherical tank printing products.

[0009] The beneficial effects of adopting the above technical solution are as follows: when wire-arc additive manufacturing is used to manufacture engineering parts with overhanging structures, the printing and stacking direction is affected by gravity, and the melt in the molten pool falls freely. Gravity pulls down the melt, resulting in a rough surface of the printed overhanging structure parts, or even failure to form. Auxiliary support structures are usually required to be installed or additionally printed, which greatly limits the accuracy and quality of wire-arc additive manufacturing and also causes waste of materials. The present application adopts a multi-axis motion printing system based on the structural characteristics of spherical tank containers. Through multi-axis rotation, the tangent of the cross-section of the spherical tank container is always pointed to the center of the earth, that is, the printing and stacking direction is always consistent with the direction of gravity, and the molten pool is evenly and fully supported by the original structure, achieving self-supporting vertical printing, ensuring that the morphology of the molten pool remains unchanged, so that the surface morphology of the workpiece is uniform.

[0010] In a feasible implementation manner, the multi-axis motion printing system includes:

[0011] An X-axis feed module is provided with a print positioner for moving the print positioner in the X-axis direction; a Z-axis feed module is vertically provided with a Y-axis feed module for moving the Y-axis feed module in the Z-axis direction; a Y-axis feed module is provided with a print tooling module for moving the print tooling module in the Y-axis direction; the print positioner has horizontal and vertical rotation functions and is a support platform for printing products of liquid hydrogen storage spherical tanks; and a print tooling module is arranged on the Y-axis feed module and has telescopic and end rotation functions and is provided with tooling for realizing additive and subtractive manufacturing of printing products of liquid hydrogen storage spherical tanks; the tooling includes a printing mechanism, a milling mechanism, a micro-arc oxidation mechanism and a thermal spray gun mechanism; a quick-change device is used to install a variety of tooling that can achieve rapid changeover.

[0012] In a feasible implementation manner, the multi-axis motion printing system includes:

[0013] An X-axis feed module is provided with a print positioner for movement in the X-axis direction; the print positioner has horizontal and vertical rotation functions and is a support platform for printing products of liquid hydrogen storage spherical tanks; a quick-change device is used to install a variety of tooling that can achieve rapid changeover; a gantry mobile gantry mechanism is a gantry robotic arm device that can achieve three-axis movement in the space in the X-axis, Y-axis and Z-axis directions.

[0014] In a feasible implementation manner, the gantry moving truss mechanism includes:

[0015] The X-axis module is used to move the printing mechanism in the X-axis direction, and it includes a motor, a coupling, a transmission shaft, a gear rack and a linear guide connected in sequence; the Y-axis module is used to move the printing mechanism in the Y-axis direction, and it includes a motor, a gear rack and a linear guide connected in sequence; the Y-axis module is also provided with a support platform, and the support platform is provided with a digital multi-functional power supply and control system, a printing consumables feeding and control system and a controller; the Z-axis module is used to move the printing mechanism in the Z-axis direction, and it includes a motor, a gear rack and a linear guide connected in sequence; the printing mechanism, which moves up and down on the Y-axis, includes a robotic arm with two rotational degrees of freedom, and different functions can be realized by replacing tooling.

[0016] In a feasible implementation manner, the digital multifunctional power supply and control system includes a plasma arc power supply control system and a micro-arc oxidation control system;

[0017] The plasma arc power supply control system is used to provide power for the printing tooling module and control the arc power of the printing tooling module in the additive and subtractive manufacturing process of the liquid hydrogen storage spherical tank, so as to achieve uniform and refined internal structure of the printed product and precise and controllable appearance; the micro-arc oxidation control system is used to control the discharge power of the micro-arc oxidation mechanism in the multi-axis motion printing system, so as to achieve the printing and generation of the inner surface coating of the printed product liquid hydrogen storage spherical tank.

[0018] The beneficial effects of adopting the above technical solution are as follows: the plasma arc power supply and control system are used as the power supply of the printing mechanism to control the shape and power of the arc of the printing mechanism during the arc additive manufacturing process. The arc power can be matched and controlled according to the different printing materials (aluminum-magnesium alloy or Invar alloy) selected in the printing, the printing speed, the corresponding wire diameter and the wire feeding speed to ensure that the required extruded metal wire can be fully melted without too much redundant heat, and prevent excessive heat accumulation and harmful thermal effects of the printed body from causing the printed body to collapse during the printing process, and the printed body to be thermally deformed and the performance of the printed body to deteriorate after printing, so as to achieve uniform surface morphology of the workpiece, uniform, refined and controllable internal microstructure, and obtain excellent product geometric morphology accuracy and material properties.

[0019] The plasma arc power supply and control system serve as the power supply of the micro-arc oxidation mechanism and are used to control the discharge power of the micro-arc oxidation mechanism. The micro-arc oxidation mechanism is used to generate an alumina ceramic layer about 30 microns thick on the inner surface of the printed body. The ceramic layer is characterized by high density and firm bonding to the substrate. The alumina coating has been proven to have extremely high resistance to hydrogen permeation, chemical inertness and wear resistance. The alumina coating can also be used as a thermal insulation coating (with extremely low thermal conductivity) to further improve the thermal insulation performance. When the printing material is Invar alloy, the device can be used to plasma thermally spray zirconium oxide powder on the Invar alloy to form a surface thermal insulation and hydrogen permeation resistant coating.

[0020] Micro-arc oxidation is a process in which a high voltage (DC, AC or pulse) is applied between the aluminum alloy workpiece and the tungsten electrode to break down the medium in an over-oxidizing gas environment or in a weakly alkaline electrolyte solution as an insulating medium, forming a transient arc, resulting in the formation of an aluminum oxide ceramic film layer on the surface of the aluminum alloy in the discharge area; Micro-arc oxidation of aluminum alloys can produce a strong connection, and its connection strength can reach more than half of the strength of the metal material;

[0021] Micro-arc oxidation of aluminum alloys is simple to prepare, low in cost, and highly efficient, and has the characteristics of low temperature, low energy, and low pollution. In addition, micro-arc oxidation of aluminum alloys can easily control parameters to obtain oxide film structures with different densities. The high density has a strong ability to prevent hydrogen penetration, while the low-density porous structure has a low thermal conductivity and better thermal insulation performance.

[0022] In a feasible implementation manner, the X-axis feed module includes an X-axis motor, an X-axis transmission screw and an X-axis feed nut which are connected in sequence.

[0023] In a feasible implementation manner, the Z-axis feed module comprises a Z-axis motor, a Z-axis transmission screw and a Z-axis feed nut connected in sequence, and a support platform connected to the Z-axis transmission screw; a digital multifunctional power supply and control system, a printing consumables feeding and control system and a controller are provided on the support platform;

[0024] The printing consumables feeding and control system comprises a wire feeding mechanism, a material tray and a gas cylinder; the wire feeding mechanism is connected to the printing tooling module through a hose; the material tray and the gas cylinder are arranged on the supporting platform.

[0025] In a feasible embodiment, the Y-axis feed module includes a lifting motor, a chain and a linear guide, an H-axis, a telescopic mechanism for driving the H-axis, an N-axis vertically connected to the H-axis, a small swing arm connected to the N-axis and a first M-axis connected to the small swing arm, an end execution axis connected to the first M-axis and a printing tooling module connected to the end execution axis.

[0026] In a feasible embodiment, the printing positioner includes a W-axis, a W-axis gear connected to the W-axis, a slewing support connected to the W-axis, a central rotating mechanism, a second M-axis arranged on the central rotating mechanism, an M-axis motor for driving the second M-axis to rotate, a V-axis, a V-axis motor for driving the V-axis, a swing mechanism connected to the V-axis, and a slewing arm connected to the swing mechanism.

[0027] According to the second aspect disclosed in the present application, the present application provides a method for additively preparing a liquid hydrogen storage spherical tank, comprising the following steps:

[0028] Using single-phase aluminum-magnesium alloy or Invar alloy as the printing material, the arc power of the printing mechanism of the digital multifunctional power supply and control system during the additive and subtractive manufacturing process of the liquid hydrogen storage spherical tank is set according to the printing speed, wire diameter and wire feeding speed;

[0029] The above-mentioned liquid hydrogen storage spherical tank additive manufacturing device is used to perform additive manufacturing according to the G-code path control program corresponding to the inner and outer surfaces of the spherical tank body, and the spherical tank body is printed;

[0030] Under peroxoxia environment or weak alkaline electrolyte solution conditions, micro-arc oxidation treatment is performed on the inner surface of the spherical tank according to the G-code path control program corresponding to the inner surface of the spherical tank to obtain a liquid hydrogen storage spherical tank with an internal coating.

[0031] The beneficial effects of adopting the above technical scheme are as follows: the present application manufactures the spherical tank body through wire-arc additive manufacturing, and the material adopts a single-phase aluminum-magnesium alloy system. A dense alumina ceramic layer is formed on its inner surface by micro-arc oxidation technology. The alumina coating can be firmly combined with the aluminum substrate. At the same time, the alumina coating has extremely high resistance to hydrogen permeability, which can effectively protect the tank body; secondly, the spherical tank body is manufactured through wire-arc additive manufacturing, and the Invar alloy system is adopted as a whole. This type of alloy has the characteristics of no low-temperature brittleness and low hydrogen embrittlement sensitivity. At the same time, zirconium oxide powder can be plasma-sprayed on the Invar alloy to form a surface heat-insulating and hydrogen-resistant permeation coating; at the same time, the present application adopts multi-axis rotation to realize that the tangent of the cross-section of the spherical tank container is always pointed to the center of the earth, that is, the printing stacking direction is always consistent with the gravity direction, and the molten pool is evenly and completely supported by the original structure, so as to achieve self-supporting vertical printing, ensuring that the molten pool morphology remains unchanged, so that the surface morphology of the workpiece is uniform.

[0032] In a feasible implementation, the arc power of the printing mechanism of the digital multifunctional power supply and control system during the additive and subtractive manufacturing process of the liquid hydrogen storage spherical tank is set according to the printing speed, wire diameter and wire feeding speed; specifically:

[0033] The wire diameter is 1.2-2.6 mm; the ratio of the printing speed to the wire feeding speed is 5-64; the arc power of the digital multifunctional power supply and control system is 3000-5600.

[0034] The beneficial effects of adopting the above technical solution are as follows: the plasma arc power supply and control system are used as the power supply of the printing mechanism to control the shape and power of the arc of the printing mechanism during the arc additive manufacturing process. The arc power can be matched and controlled according to the different printing materials (aluminum-magnesium alloy or Invar alloy) selected in the printing, the printing speed, the corresponding wire diameter and the wire feeding speed, to ensure that the required extruded metal wire can be fully melted without too much redundant heat, to prevent the excessive heat accumulation and harmful thermal effects of the printed body from causing the printed body to collapse during the printing process, the printed body to be thermally deformed after printing and the performance of the printed body to deteriorate, so as to achieve uniform surface morphology of the workpiece, uniform, refined and controllable internal microstructure, and obtain excellent product geometric morphology accuracy and material properties.

[0035] In a feasible implementation, the inner surface of the spherical tank is subjected to micro-arc oxidation treatment according to the G-code path control program corresponding to the inner surface of the spherical tank under a peroxic environment or a weakly alkaline electrolyte solution to obtain a liquid hydrogen storage spherical tank with an internal coating; specifically:

[0036] When a single-phase aluminum-magnesium alloy is used as the printing material, when the oxygen content is 50% to 60%, a micro-arc oxidation treatment is performed on the inner surface of the spherical tank body according to a G code path control program corresponding to the inner surface of the spherical tank body to obtain an aluminum oxide film coating combined with the inner surface of the spherical tank body;

[0037] When Invar alloy material is used as the printing material, according to the G code path control program corresponding to the inner surface of the spherical tank body, plasma thermal spraying zirconium oxide powder technology is used to perform micro-arc oxidation treatment to obtain a zirconium oxide film coating combined with the inner surface of the spherical tank body.

[0038] In a feasible implementation, a liquid hydrogen storage spherical tank additive manufacturing device is used to perform additive manufacturing according to a G-code path control program corresponding to the inner and outer surfaces of the spherical tank body, and the spherical tank body is printed; specifically:

[0039] Start the X-axis feed module and move the printing positioner to the preparation work area;

[0040] Position the printing substrate made of single-phase aluminum-magnesium alloy or Invar alloy on the printing positioner, and then move the printing fixture module to the quick-change device by cooperating with the Z-axis feeding module and the Y-axis feeding module, and connect the printing mechanism with the printing fixture module; and then move the connected printing fixture module to the working area through the Z-axis feeding module and the Y-axis feeding module;

[0041] Start the printing positioner, rotate the printing substrate 90 degrees along the V axis to the horizontal plane, and print according to the G code path control program and set process parameters corresponding to the inner and outer surfaces of the spherical tank body. At the same time, rotate the M axis and V axis in the printing positioner to form a printing rotary body;

[0042] Then, the Z-axis feed module and the Y-axis feed module cooperate to move the printing tooling module to the quick-change device, engage the milling mechanism with the printing tooling module, and then move the engaged printing tooling module to the working area through the Z-axis feed module and the Y-axis feed module to perform subtractive processing on the inner and outer surfaces to obtain a printed spherical tank body. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a three-dimensional structural diagram of the additive manufacturing device for the liquid hydrogen storage spherical tank of Example 1 of the present application.

[0044] Figure 2 This is a three-dimensional structural diagram of the additive manufacturing device for the liquid hydrogen storage spherical tank of Example 2 of the present application.

[0045] Figure 3 This is a three-dimensional structural diagram of the X-axis feed module and the printing positioner of Example 1 of the present application.

[0046] Figure 4 This is a schematic diagram of the structure of the Z-axis feed module and the Y-axis feed module of Example 1 of the present application.

[0047] Figure 5 Schematic diagram of the structure of the quick-change device according to an embodiment of the present application.

[0048] Figure 6This is a structural schematic diagram of the gantry moving truss mechanism implemented in embodiment 2 of the present application.

[0049] Figure 7 It is a structural schematic diagram of the X-axis module of the gantry moving gantry mechanism.

[0050] Figure 8 It is a structural schematic diagram of the Z-axis module of the gantry moving gantry mechanism.

[0051] Fig. 9 It is a structural schematic diagram of the Y-axis module of the gantry moving gantry mechanism.

[0052] Fig.10 This is a flow chart of the additive manufacturing method for a liquid hydrogen storage spherical tank according to an embodiment of the present application.

[0053] Fig.11 This is a macroscopic morphology of the product produced under different parameter conditions of the additive manufacturing method for liquid hydrogen storage spherical tanks in this application.

[0054] Fig.12 This is the macroscopic morphology of the single-phase aluminum-magnesium alloy low-power input additive manufacturing sample in the additive manufacturing method of the liquid hydrogen storage spherical tank in this application.

[0055] In the figure, 1, X-axis feed module; 1-1, X-axis motor; 1-2, X-axis transmission screw; 1-3, X-axis feed nut; 2, Z-axis feed module; 2-1, Z-axis motor; 2-2, Z-axis transmission screw; 2-3, Z-axis feed nut; 3, Y-axis feed module; 3-1, telescopic mechanism; 3-2, lifting motor; 3-3, gear; 3-4, wire feeding mechanism; 3-5, gas cylinder; 3-6, H axis; 3-7, N axis; 3-8, small pendulum arm; 3-9, first M axis; 3-10, end execution axis; 3-11, printing tooling module; 3-12, material tray; 3-13, controller; 3-14, linear guide; 3-15, support platform; 4, printing positioner; 4-1, W axis gear; 4-2, slewing support; 4-3, M axis motor; 4-4, swing mechanism; 4-5, center rotation mechanism; 4-6, printing product; 4-7, slewing arm; 4-8, V axis motor; 4- 9. V-axis; 4-10. Second M-axis; 4-11. W-axis; 5. Printing tooling module; 6. Printing products; 7. Quick-change device; 7-1. Micro-arc oxidation mechanism; 7-2. 3D printing mechanism; 7-3. Milling mechanism; 7-4. Quick-change fixture; 8. Gantry moving truss mechanism; 8-1. X-axis module; 8-1-1. X-axis module motor; 8-1-2. X-axis module coupling; 8-1-3. X-axis module transmission shaft; 8-1-4. X-axis module rack and pinion; 8-1-5, X-axis linear guide; 8-2, Z-axis module; 8-2-1, Z-axis module motor; 8-2-2, Z-axis module rack and pinion; 8-2-3, Z-axis module linear guide; 8-3, Y-axis module; 8-3-1, Y-axis membrane group motor; 8-3-2, Y-axis module rack and pinion; 8-3-3, Y-axis module linear guide; 8-4, gantry truss quick-change tooling; 8-5, gantry mobile truss support platform. DETAILED DESCRIPTION

[0056] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0057] Hydrogen is an ideal and important energy source. The volumetric energy storage density of liquid hydrogen can reach 800 times that of gaseous hydrogen. Therefore, it is most ideal to store and transport it in the form of liquid hydrogen. However, the temperature of liquid hydrogen is very low, about -252.87℃, which brings two potential hazards to the materials used in the tanks for storage and transportation: first, low temperature may cause the plastic toughness of the material to drop sharply, resulting in low-temperature embrittlement; second, the strong diffusibility of hydrogen may cause hydrogen-induced brittle fracture of the material. Therefore, the material selection of liquid hydrogen storage tanks must avoid low-temperature embrittlement and hydrogen embrittlement.

[0058] At the same time, the lining of liquid hydrogen storage tanks can be made of Invar alloy / modified stainless steel and welded using a similar process. The lining of large liquid hydrogen tanks is also formed by manually laying Invar alloy sheets and manually welding them. In general, the manufacturing process of liquid hydrogen storage tanks, especially large spherical tanks, is complex, long, and costly.

[0059] In response to the above problems, the present application proposes an additive manufacturing device and method for liquid hydrogen storage spherical tanks. By using the additive manufacturing device for liquid hydrogen storage spherical tanks to perform printing and manufacturing under set conditions, a liquid hydrogen storage spherical tank with uniform surface morphology and uniform, refined and controllable internal microstructure is formed, thereby solving the problem of difficulties in the existing preparation process of liquid hydrogen storage spherical tanks.

[0060] The present application firstly manufactures a spherical tank body by wire-arc additive manufacturing, wherein the material is a single-phase aluminum-magnesium alloy system, and a dense alumina ceramic layer is formed on the inner surface thereof by micro-arc oxidation technology. The alumina coating can be firmly combined with the aluminum substrate, and at the same time, the alumina coating has extremely high resistance to hydrogen permeation, and can effectively protect the tank body; secondly, manufactures a spherical tank body by wire-arc additive manufacturing, wherein the whole body adopts the Invar alloy system, which is characterized by no low-temperature brittleness and low hydrogen embrittlement sensitivity. At the same time, the Invar alloy can be subjected to plasma thermal spraying of zirconium oxide powder to form a surface heat-insulating and hydrogen-permeation-resistant coating.

[0061] When wire-arc additive manufacturing is used to manufacture engineering parts with overhanging structures, the printing and stacking direction is affected by gravity, and the molten pool melt falls freely. Gravity pulls down the melt, resulting in a rough surface of the printed overhanging structure parts, or even failure to form. Auxiliary support structures are usually required to be installed or additionally printed, which greatly limits the accuracy and quality of wire-arc additive manufacturing and also causes material waste. The present application adopts multi-axis rotation to achieve that the tangent of the cross-section of spherical tank containers always points to the center of the earth, that is, the printing and stacking direction is always consistent with the direction of gravity, and the molten pool is evenly and completely supported by the original structure. The corresponding G-code planning path is determined by geometric calculation to achieve self-supporting vertical printing, which ensures that the molten pool morphology remains unchanged, so that the surface morphology of the workpiece is uniform and consistent.

[0062] The following is a detailed description of the technical solution of the surface roughness classification method of the thermal protection material provided by the present application through specific embodiments. It should be noted that the following embodiments can exist alone or in combination with each other, and the same or similar contents may not be repeated in different embodiments.

[0063] Example 1

[0064] Figure 1 For the liquid hydrogen storage spherical tank additive manufacturing device provided in the embodiment of the present application, see Figure 1 , the liquid hydrogen storage spherical tank additive manufacturing device provided in this embodiment includes: a multi-axis motion printing system, a digital multifunctional power supply and control system, a printing consumables feeding and control system and a controller;

[0065] The digital multifunctional power supply and control system and the printing consumables feeding and control system are all connected to the multi-axis motion printing system; the multi-axis motion printing system, the digital multifunctional power supply and control system, and the printing consumables feeding and control system are all electrically connected to the controller to control the preparation of liquid hydrogen storage spherical tank printing products.

[0066] See also Figures 3 to 5 According to one embodiment of the present application, the multi-axis motion printing system includes: an X-axis feeding module 1, on which a printing positioner 4 is provided, for moving the printing positioner 4 in the X-axis direction; the X-axis feeding module 1 includes an X-axis motor 1-1, an X-axis transmission screw 1-2 and an X-axis feeding nut 1-3 connected in sequence;

[0067] A Z-axis feeding module 2 is vertically provided with a Y-axis feeding module 3 for moving the Y-axis feeding module 3 in the Z-axis direction; the Z-axis feeding module 2 comprises a Z-axis motor 2-1, a Z-axis transmission screw 2-2 and a Z-axis feeding nut 2-3 connected in sequence and a supporting platform 3-15 connected to the Z-axis transmission screw 2-2; the supporting platform 3-15 is provided with a digital multifunctional power supply and control system, a printing consumables feeding and control system and a controller 3-13;

[0068] Digital multifunctional power supply and control system includes plasma arc power supply control system and micro-arc oxidation control system; plasma arc power supply control system can be Fronius TPS 600iCMT or Fronius CMT 4000Adv; the micro-arc oxidation control system can be JHMAO-200KVA; the plasma arc power supply control system is used to provide power for the printing tooling module 5 and control the arc power of the printing tooling module in the process of additive and subtractive manufacturing of liquid hydrogen storage spherical tanks, so as to achieve uniform and refined internal structure of the printed product and precise and controllable appearance morphology; the plasma arc power supply and control system, as the power supply of the printing mechanism, is used to control the shape and power of the arc of the printing mechanism in the process of arc additive manufacturing. The arc power can be matched and controlled according to the different printing materials (aluminum-magnesium alloy or Invar alloy) selected in the printing, the printing speed, the corresponding wire diameter, and the wire feeding speed to ensure that the required extruded metal wire can be fully melted without too much redundant heat, to prevent the excessive heat accumulation and harmful thermal effects of the printed body from causing the printed body to collapse during the printing process, and the thermal deformation of the printed body after printing and the deterioration of the performance of the printed body, so as to achieve uniform surface morphology of the workpiece, uniform and refined internal microstructure, and excellent product geometric morphology accuracy and material properties.

[0069] The micro-arc oxidation control system is used to control the discharge power of the micro-arc oxidation mechanism in the multi-axis motion printing system to realize the printing generation of the inner surface coating of the liquid hydrogen storage spherical tank of the printing product.

[0070] The plasma arc power supply and control system serve as the power supply of the micro-arc oxidation mechanism and are used to control the discharge power of the micro-arc oxidation mechanism 7-1. The micro-arc oxidation mechanism 7-1 is used to generate an alumina ceramic layer about 30 microns thick on the inner surface of the printed body. The ceramic layer is characterized by high density and firm bonding to the substrate. The alumina coating has been proven to have extremely high resistance to hydrogen permeation, chemical inertness and wear resistance. The alumina coating can also be used as a thermal insulation coating (with extremely low thermal conductivity) to further improve the thermal insulation performance (except for the vacuum insulation structure). When the printing material is Invar alloy, the device can be used to plasma thermally spray zirconium oxide powder on the Invar alloy to form a surface thermal insulation and hydrogen permeation resistant coating.

[0071] The principle of the microarc oxidation (MAO) process is to apply a (DC, AC or pulse) high voltage between the aluminum alloy workpiece and the tungsten electrode to break down the medium in an overoxidized gas environment or in a weakly alkaline electrolyte solution as an insulating medium, forming a transient arc, resulting in the formation of an aluminum oxide ceramic film layer on the surface of the aluminum alloy in the discharge area; Microarc oxidation of aluminum alloys can produce a strong connection, and its connection strength can reach more than half of the strength of the metal material; The characteristics of microarc oxidation of aluminum alloys are simple preparation, low cost and high efficiency. It has the characteristics of low temperature, low energy and low pollution. In addition, microarc oxidation of aluminum alloys can easily obtain oxide film structures with different densities by controlling parameters. The high density has a strong ability to prevent hydrogen penetration, while the low density porous structure has a low thermal conductivity and good thermal insulation performance; The printing consumables feeding and control system includes a wire feeding mechanism 3-4, a material tray 3-12 and a gas cylinder 3-5; the wire feeding mechanism is connected to the printing tooling module 3-11 through a hose; the material tray 3-12 and the gas cylinder 3-5 are arranged on a support platform 3-15.

[0072] The multi-axis motion printing system also includes a Y-axis feed module 3, on which a printing tooling module 3-11 is provided for moving the printing tooling module 3-11 in the Y-axis direction; the Y-axis feed module 3 includes a lifting motor 3-2, a gear 3-3 and a linear guide rail 3-14, an H-axis 3-6, a telescopic mechanism 3-1 for driving the H-axis, an N-axis 3-7 vertically connected to the H-axis 3-6, a small swing arm 3-8 connected to the N-axis 3-7 and a first M-axis 3-9 connected to the small swing arm 3-8, an end execution axis 3-10 connected to the first M-axis 3-9 and a printing tooling module 3-11 connected to the end execution axis 3-10.

[0073] The printing positioner 4 has the function of rotating in the horizontal and vertical directions and is a support platform for printing products of liquid hydrogen storage spherical tanks; the printing positioner 4 includes a W-axis 4-11, a W-axis gear 4-1 connected to the W-axis 4-11, a slewing support 4-2 connected to the W-axis 4-11, a center rotating mechanism 4-5, a second M-axis 4-10 arranged on the center rotating mechanism 4-5, an M-axis motor 4-3 for driving the second M-axis 4-10 to rotate, a V-axis 4-9, a V-axis motor 4-8 driving the V-axis 4-9, a swing mechanism 4-4 connected to the V-axis 4-9, and a slewing arm 4-7 connected to the swing mechanism 4-4.

[0074] The printing tooling module 5 is arranged on the Y-axis feeding module 3, has the functions of telescopic and end rotation, and is provided with a tooling to realize the additive and subtractive material manufacturing of the liquid hydrogen storage spherical tank printing product; the tooling includes a 3D printing mechanism 7-2, a milling mechanism 7-3, a micro-arc oxidation mechanism 7-1 and a thermal spray gun mechanism;

[0075] The quick-change device 7 is used to install a variety of tooling that can achieve rapid changeover; a tooling with a quick-change fixture 7-4 is installed on it; according to one embodiment of the present application, the tooling includes a 3D printing mechanism 7-2, a milling mechanism 7-3, a micro-arc oxidation mechanism 7-1 and a thermal spray gun.

[0076] Example 2

[0077] This embodiment is an improvement on the basis of embodiment 1, and the difference from embodiment 1 is: Figure 2 The multi-axis motion printing system of this embodiment includes: an X-axis feeding module, on which a printing positioner is provided, which is used to move the printing positioner in the X-axis direction; the printing positioner has the function of rotating in the horizontal direction and the vertical direction, and is used as a support platform for printing products of liquid hydrogen storage spherical tanks; a quick-change device is used to install a variety of tooling that can achieve rapid changeover; a gantry moving gantry mechanism, which is a gantry mechanical arm device that can realize three-axis movement in the space in the X-axis, Y-axis and Z-axis directions;

[0078] See also Figure 6-Figure 9 The gantry moving gantry mechanism 8 includes: an X-axis module 8-1, which is used to move the printing mechanism in the X-axis direction, and includes an X-axis module motor 8-1-1, an X-axis module coupling 8-1-2, an X-axis module transmission shaft 8-1-3, an X-axis module gear rack 8-1-4 and an X-axis module linear guide 8-1-5 connected in sequence;

[0079] The Y-axis module 8-3 is used to move the printing mechanism in the Y-axis direction, and includes a Y-axis membrane group motor 8-3-1, a Y-axis module gear rack 8-3-2 and a Y-axis module linear guide 8-3-3 connected in sequence; the Y-axis module is also provided with a gantry quick-change tooling 8-4 and a gantry mobile gantry support platform 8-5, and the gantry mobile gantry support platform 8-5 is provided with a digital multi-functional power supply and control system, a printing consumables feeding and control system and a controller; the Z-axis module 8-3 is used to move the printing mechanism in the Z-axis direction, and includes a Z-axis module motor 8-3-1, a Z-axis module gear rack 8-3-2 and a Z-axis module linear guide 8-3-3 connected in sequence; the printing mechanism, which moves up and down on the Y-axis, includes a robotic arm with two rotational degrees of freedom, and different functions can be realized by replacing the tooling.

[0080] Example 3

[0081] like Fig.10 As shown, according to one embodiment of the present application, based on the liquid hydrogen storage spherical tank additive manufacturing device of embodiment 1 and embodiment 2, the present application provides a liquid hydrogen storage spherical tank additive manufacturing method, which includes:

[0082] Using single-phase aluminum-magnesium alloy or Invar alloy as the printing material, the arc power of the printing mechanism of the digital multifunctional power supply and control system during the additive and subtractive manufacturing process of the liquid hydrogen storage spherical tank is set according to the printing speed, wire diameter and wire feeding speed;

[0083] According to one embodiment of the present application, the power output power of the power supply matching the alloy type, wire diameter and wire feeding speed (deposition rate) is set, and the setting parameters include the ratio of AC (variable polarity) and DC, the pulse current size, the pulse frequency and the duty cycle, as shown in Table 1 below:

[0084] Table 1 Specific process parameters of single-phase aluminum-magnesium alloy additives that cannot be formed and are suitable for forming

[0085]

[0086] See also Fig.11 , Fig.11 Macroscopic morphology of two additive manufacturing parameters of single-phase aluminum-magnesium alloy specimens. The left side has too high forming power, resulting in shape collapse, while the right side has appropriate forming power and has a regular geometric shape. Fig.12 It is the macroscopic morphology of the low-power input additive sample of single-phase aluminum-magnesium alloy. It can be seen that there are obvious unfused areas on the surface. Therefore, by adjusting the power supply parameters, the power supply power that matches the alloy type, wire diameter and wire feeding speed (deposition rate) is set.

[0087] The above-mentioned liquid hydrogen storage spherical tank additive manufacturing device is used to perform additive manufacturing according to the G-code path control program corresponding to the inner and outer surfaces of the spherical tank body, and the spherical tank body is printed;

[0088] According to an embodiment of the present application, the additive path control program prints the spherical tank body blank according to the G code deposition path corresponding to the vertical tangent of the spherical tank body contour line in the coordinate system; taking a sphere with a diameter of Φ = 1600 mm as an example, the additive path G code control program (U angle, V angle, B wire length and F speed) given by the wire diameter of 1.2 mm and the magnification ratio of 10 is as follows (the first 5 degrees of the V angle program, the 90-degree hemisphere is detailed in Table 2 below):

[0089] Table 2 Additive path control program

[0090]

[0091] U: Roll axis, generally a multiple of 360 degrees, corresponding to the second M axis of the print positioner 4, controls the rotation of the rotating body; V: Pitch axis, corresponding to 0-180 degree change when printing a hemisphere, corresponding to the V axis of the print positioner 4, controls the rocker arm; B: The length of the printing wire used, which is the total length of the wire output by the printing consumables feeding system at a certain moment in a certain printing process, and is controlled and recorded by the material tray in the printing consumables feeding and control system; F: The wire feeding speed during the printing process, which is controlled and recorded by the wire feeding mechanism in the printing consumables feeding and control system, and B and F are linkage variables;

[0092] Cutting of the inner and outer surfaces of the sphere: CNC rough and fine machining is performed according to the G code path corresponding to the inner and outer surfaces of the spherical tank in the coordinate system to achieve the required surface finish.

[0093] Under peroxoxia environment or weak alkaline electrolyte solution conditions, micro-arc oxidation treatment is performed on the inner surface of the spherical tank according to the G-code path control program corresponding to the inner surface of the spherical tank to obtain a liquid hydrogen storage spherical tank with an internal coating.

[0094] According to one embodiment of the present application, a method for additive manufacturing using an additive manufacturing device for a liquid hydrogen storage spherical tank includes: an inner tank body preparation process flow:

[0095] Wire-arc additive manufacturing of the inner tank body: The tank body is first divided into two halves and printed separately, and then the inner and outer surfaces are processed, and then the two hemispheres are welded together through the 3D printing nozzle after being combined; specifically:

[0096] Start the X-axis feeding module 1, use its guide rail to move the printing positioner 4 to the preparation work area, place the printing substrate (which can be a cylindrical tube of sufficient thickness of the same material as the printing product, that is, a single-phase aluminum-magnesium alloy or Invar alloy material), position and clamp the printing substrate on the printing positioner 4, and fix the printing substrate to the platform at one end of the second M-axis by using bolts or welding. During the printing process, the second M-axis gear of the printing positioner 4 rotates to drive the printing substrate to rotate; after the printing substrate is clamped, start the X-axis feeding module 1, use its guide rail to transfer the printing positioner 4 and the fixed printing base to the printing work area, and then set the current workpiece coordinates; The Z-axis feed module 2 cooperates with the Y-axis feed module 3 to move the printing tooling module 5 to the quick-change device 7, and the print head of the 3D printing mechanism 7-2 is joined with the printing tooling module 5 by means of the quick-change fixture 7-4 manually or by an industrial robot. After the joining is completed, the Z-axis feed module 2 and the Y-axis feed module 3 cooperate to move the printing tooling module 5 to the working area, and then the printing positioner 4 is started to rotate the printing substrate 90 degrees along the V-axis 4-9 to be parallel to the horizontal plane, and printing is started according to the trajectory path generated by the computer slicing and the set printing process parameters. At the same time, the second M-axis 4-10 and the V-axis 4-9 in the printing positioner 4 are rotated to form a printing rotary body.

[0097] In-situ machining of the inner and outer surfaces of the inner tank body: After the hemispherical printing is completed, the Z-axis feed module 2 and the Y-axis feed module 3 of the driving unit are then driven, and the printing fixture module 5 cooperates to return the printing fixture module 5 to the tool quick change device 7, place the print head back to the quick change device 7, and switch to the milling head of the milling mechanism 7-3, continue to return to the working area, and switch to the subtractive surface treatment program to perform on the inner and outer surfaces of the hemispherical printed body; after the surface treatment, the workpiece is driven by the X-axis feed module 1 to drive the print positioner 4 to move to the preparation work area, and the workpiece is manually hoisted out of the workstation through the X-axis feed module 1 and the print positioner 4. Micro-arc oxidation of the inner surface of the composite equipment inner tank body: Under the condition that the inner tank body is filled with weak alkaline electrolyte solution as an insulating medium, a micro-arc oxidation mechanism is used to apply (DC, AC or pulse) high voltage between the aluminum alloy printed workpiece and the tungsten electrode to break down the medium, forming a transient arc, resulting in the formation of an aluminum oxide ceramic film layer on the surface of the aluminum alloy tank body in the discharge area.

[0098] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A liquid hydrogen storage spherical tank additive manufacturing device, characterized in that: include: Multi-axis motion printing system, digital multi-functional power supply and control system, printing consumables feeding and control system and controller; The digital multifunctional power supply and control system and the printing consumables feeding and control system are all connected to the multi-axis motion printing system; and the multi-axis motion printing system, the digital multifunctional power supply and control system, and the printing consumables feeding and control system are all electrically connected to the controller to control the preparation of the liquid hydrogen storage spherical tank printing product; The digital multifunctional power supply and control system includes a plasma arc power supply control system and a micro-arc oxidation control system; The plasma arc power supply control system is used to provide power to the printing tooling module and control the arc power of the printing tooling module in the process of additive and subtractive manufacturing of liquid hydrogen storage spherical tanks, so as to achieve uniform and refined internal structure of the printed product and precise and controllable appearance; The micro-arc oxidation control system is used to control the discharge power of the micro-arc oxidation mechanism in the multi-axis motion printing system to realize the generation of the inner surface coating of the liquid hydrogen storage spherical tank of the printed product.

2. The liquid hydrogen storage spherical tank additive manufacturing device according to claim 1 is characterized in that: The multi-axis motion printing system comprises: An X-axis feeding module, on which a printing positioner is provided, for movement of the printing positioner in the X-axis direction; a Z-axis feeding module, on which a Y-axis feeding module is vertically provided, for movement of the Y-axis feeding module in the Z-axis direction; a Y-axis feeding module, on which a printing tooling module is provided, for movement of the printing tooling module in the Y-axis direction; a printing positioner, which has horizontal and vertical rotation functions, and is used as a support platform for printing products of liquid hydrogen storage spherical tanks; and The printing tooling module is arranged on the Y-axis feeding module, has the functions of telescopic and end rotation, and is provided with a tooling to realize the additive and subtractive manufacturing of the liquid hydrogen storage spherical tank printing product; the tooling includes a printing mechanism, a milling mechanism, a micro-arc oxidation mechanism and a thermal spray gun mechanism; Quick-change device, used to install a variety of tooling that can achieve rapid changeover.

3. The liquid hydrogen storage spherical tank additive manufacturing device according to claim 1 is characterized in that: The multi-axis motion printing system comprises: An X-axis feed module is provided with a print positioner for movement in the X-axis direction; the print positioner has horizontal and vertical rotation functions and is a support platform for printing products of liquid hydrogen storage spherical tanks; a quick-change device is used to install a variety of tooling that can achieve rapid changeover; a gantry mobile gantry mechanism is a gantry robotic arm device that can achieve three-axis movement in the space in the X-axis, Y-axis and Z-axis directions.

4. The liquid hydrogen storage spherical tank additive manufacturing device according to claim 3 is characterized in that: The gantry moving truss mechanism comprises: The X-axis module is used to move the printing mechanism in the X-axis direction, and it includes a motor, a coupling, a transmission shaft, a gear rack and a linear guide connected in sequence; the Y-axis module is used to move the printing mechanism in the Y-axis direction, and it includes a motor, a gear rack and a linear guide connected in sequence; the Y-axis module is also provided with a support platform, and the support platform is provided with a digital multi-functional power supply and control system, a printing consumables feeding and control system and a controller; the Z-axis module is used to move the printing mechanism in the Z-axis direction, and it includes a motor, a gear rack and a linear guide connected in sequence; the printing mechanism, which moves up and down on the Y-axis, includes a robotic arm with two rotational degrees of freedom, and different functions can be realized by replacing tooling.

5. The liquid hydrogen storage spherical tank additive manufacturing device according to claim 2 is characterized in that: The X-axis feed module includes an X-axis motor, an X-axis transmission screw and an X-axis feed nut which are connected in sequence.

6. The liquid hydrogen storage spherical tank additive manufacturing device according to claim 2 is characterized in that: The Z-axis feed module includes a Z-axis motor, a Z-axis transmission screw and a Z-axis feed nut connected in sequence, and a support platform connected to the Z-axis transmission screw; a digital multifunctional power supply and control system, a printing consumables feeding and control system and a controller are arranged on the support platform; The printing consumables feeding and control system comprises a wire feeding mechanism, a material tray and a gas cylinder; the wire feeding mechanism is connected to the printing tooling module through a hose; the material tray and the gas cylinder are arranged on the supporting platform.

7. The liquid hydrogen storage spherical tank additive manufacturing device according to claim 2 is characterized in that: The Y-axis feeding module includes a lifting motor, gears and linear guides, an H-axis, a telescopic mechanism for driving the H-axis, an N-axis vertically connected to the H-axis, a small swing arm connected to the N-axis and a first M-axis connected to the small swing arm, an end execution axis connected to the first M-axis and a printing tooling module connected to the end execution axis.

8. The liquid hydrogen storage spherical tank additive manufacturing device according to claim 2 is characterized in that: The printing positioner includes a W-axis, a W-axis gear connected to the W-axis, a slewing support connected to the W-axis, a central rotating mechanism, a second M-axis arranged on the central rotating mechanism, an M-axis motor for driving the second M-axis to rotate, a V-axis, a V-axis motor for driving the V-axis, a swing mechanism connected to the V-axis, and a slewing arm connected to the swing mechanism.

9. A method for preparing a liquid hydrogen storage spherical tank by additive manufacturing, characterized in that: The following steps are involved: Using single-phase aluminum-magnesium alloy or Invar alloy as the printing material, the arc power of the printing mechanism of the digital multifunctional power supply and control system during the additive and subtractive manufacturing process of the liquid hydrogen storage spherical tank is set according to the printing speed, wire diameter and wire feeding speed; Using the liquid hydrogen storage spherical tank additive manufacturing device according to any one of claims 1 to 8, additive manufacturing is performed according to the G code path control program corresponding to the inner and outer surfaces of the spherical tank body, and the spherical tank body is printed; Under peroxoxia environment or weak alkaline electrolyte solution conditions, micro-arc oxidation treatment is performed on the inner surface of the spherical tank according to the G-code path control program corresponding to the inner surface of the spherical tank to obtain a liquid hydrogen storage spherical tank with an internal coating.

10. The additive manufacturing method for a liquid hydrogen storage spherical tank according to claim 9 is characterized in that: The arc power of the printing mechanism of the digital multifunctional power supply and control system during the additive and subtractive manufacturing process of the liquid hydrogen storage spherical tank is set according to the printing speed, wire diameter and wire feeding speed; specifically: The wire diameter is 1.2-2.6 mm; the ratio of the printing speed to the wire feeding speed is 5-64; the arc power of the digital multifunctional power supply and control system is 3000-5600.

11. The additive manufacturing method for a liquid hydrogen storage spherical tank according to claim 9 is characterized in that: The method comprises: performing micro-arc oxidation treatment on the inner surface of the spherical tank body according to the G code path control program corresponding to the inner surface of the spherical tank body under the peroxygen environment or weak alkaline electrolyte solution conditions to obtain a liquid hydrogen storage spherical tank with an internal coating; specifically: When a single-phase aluminum-magnesium alloy is used as the printing material, when the oxygen content is 50% to 60%, a micro-arc oxidation treatment is performed on the inner surface of the spherical tank body according to a G code path control program corresponding to the inner surface of the spherical tank body to obtain an aluminum oxide film coating combined with the inner surface of the spherical tank body; When Invar alloy material is used as the printing material, according to the G code path control program corresponding to the inner surface of the spherical tank body, plasma thermal spraying zirconium oxide powder technology is used to perform micro-arc oxidation treatment to obtain a zirconium oxide film coating combined with the inner surface of the spherical tank body.

12. The additive manufacturing method for a liquid hydrogen storage spherical tank according to claim 9 is characterized in that: The liquid hydrogen storage spherical tank additive manufacturing device according to any one of claims 1 to 9 is used to perform additive manufacturing according to the G code path control program corresponding to the inner and outer surfaces of the spherical tank body, and print the spherical tank body; Specifically: Start the X-axis feed module and move the printing positioner to the preparation work area; Position the printing substrate made of single-phase aluminum-magnesium alloy or Invar alloy on the printing positioner, and then move the printing fixture module to the quick-change device by cooperating with the Z-axis feeding module and the Y-axis feeding module, and connect the printing mechanism with the printing fixture module; Then, the joined printing tooling module is moved to the working area through the Z-axis feeding module and the Y-axis feeding module; Start the printing positioner, rotate the printing substrate 90 degrees along the V axis to the horizontal plane, and print according to the G code path control program and set process parameters corresponding to the inner and outer surfaces of the spherical tank body. At the same time, rotate the M axis and V axis in the printing positioner to form a printing rotary body; Then, the Z-axis feed module and the Y-axis feed module cooperate to move the printing tooling module to the quick-change device, engage the milling mechanism with the printing tooling module, and then move the engaged printing tooling module to the working area through the Z-axis feed module and the Y-axis feed module to perform subtractive processing on the inner and outer surfaces to obtain a printed spherical tank body.

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