Lunar base aluminum alloy additive manufacturing apparatus and method

Abstract

The application discloses a lunar base aluminum alloy additive manufacturing device and manufacturing method, relates to the lunar base aluminum alloy additive manufacturing technical field, and comprises a heating bearing assembly, a stirring assembly, a pressure injection assembly and an extrusion nozzle assembly. The heating bearing assembly comprises an outer frame support, a graphite inner cylinder is arranged in the middle of the outer frame support, a feeding pipe is arranged on the upper portion of the graphite inner cylinder, the feeding pipe and the graphite inner cylinder are mutually penetrated, and the feeding pipe is used for adding aluminum alloy raw materials into the graphite inner cylinder. Through a series of improvements such as mechanical melt feeding, solar light condensation auxiliary heating and modular integrated design, the application constructs a complete aluminum alloy additive manufacturing technical scheme which is suitable for the extreme environment conditions of the moon surface, such as high vacuum, weak gravity, large temperature difference, strong radiation, limited energy and crude raw materials, realizes in-situ, low-energy-consumption and high-quality direct manufacturing from raw materials to components, and provides a feasible technical path for on-site manufacturing of structural components of a lunar scientific research station and other large facilities.

Description

Technical Field

[0001] This invention relates to the field of lunar-based aluminum alloy additive manufacturing technology, specifically to a lunar-based aluminum alloy additive manufacturing apparatus and manufacturing method. Background Technology

[0002] The extreme environment on the lunar surface (high vacuum, weak gravity, large temperature difference, and strong radiation) poses a severe challenge to the in-situ manufacturing of metal components. Currently, extraterrestrial manufacturing technology mainly relies on the "Earth prefabrication-lunar assembly" model. This model is limited by the extremely high cost of Earth-Moon transportation and is difficult to meet the large-scale, customized manufacturing needs of metal structural components for future large-scale infrastructure such as lunar research stations.

[0003] Metal additive manufacturing technology, characterized by on-demand forming, rapid response, and controllable automation, is a potentially feasible method for manufacturing structural components for lunar research stations. Existing metal additive manufacturing technologies typically include the following components: a molten metal module, a pneumatic propulsion module, an auxiliary heat source module, and a motion platform module. The molten metal module melts the metal material using resistance heating or induction heating; the pneumatic propulsion module forces the molten metal solution to be extruded from a bottom nozzle by applying gas pressure to the molten metal surface; the auxiliary heat source module uses a non-consumable electrode inert gas shielded welding power source to reheat the molten metal droplets; and the motion platform module receives the molten metal droplets and completes the layer-by-layer additive manufacturing process. This technology has been used for micro-droplet jet printing of low-melting-point alloys in atmospheric pressure environments on Earth, but it faces challenges in the lunar vacuum environment, such as the inability to use high-pressure gas as a propulsion medium and the inability of the electric arc heat source to generate a discharge arc column in a vacuum environment. Therefore, existing molten extrusion equipment is mainly used in atmospheric pressure or protective atmosphere environments on Earth, and a reliable technical solution has not yet been developed for vacuum environments, weak gravity conditions, and scenarios with extremely limited energy.

[0004] Therefore, this invention proposes a lunar-based aluminum alloy additive manufacturing apparatus and manufacturing method. Summary of the Invention

[0005] The purpose of this invention is to provide a lunar-based aluminum alloy additive manufacturing device and manufacturing method, which can realize high-quality, low-energy consumption, and in-situ resource-adaptive aluminum alloy additive manufacturing in the lunar environment, solve the outstanding problems of existing technologies in energy utilization, material adaptation, and environmental adaptation, and provide principle verification support for the on-site manufacturing of large structural components such as lunar research stations.

[0006] According to a first aspect of the present invention, in order to achieve the above-mentioned objective, the present invention provides the following technical solution: a lunar-based aluminum alloy additive manufacturing apparatus, comprising a heating and bearing assembly, a stirring assembly, an injection assembly, and an extrusion nozzle assembly, wherein: The heating support assembly includes an outer frame support, a graphite inner cylinder installed in the middle of the outer frame support, a feeding pipe installed on the upper part of the graphite inner cylinder, the feeding pipe communicating with the graphite inner cylinder, and used to add aluminum alloy raw materials into the graphite inner cylinder; a resistance heating wire is wound around the outside of the graphite inner cylinder, and an alumina ceramic tube and an alumina fiber insulation layer are sequentially sleeved on the outside of the graphite inner cylinder. The stirring assembly includes a stirring tube fixedly installed on the upper part of the graphite inner cylinder, and a rotating stirring rod is rotatably arranged inside the stirring tube, the stirring rod extending into the graphite inner cylinder through the stirring tube; The injection assembly includes a push piston that is slidably connected inside the graphite inner cylinder. A push rod is installed on the top of the push piston, and a servo electric cylinder is installed above the push rod. The servo electric cylinder is installed on the top of the outer frame support. The extrusion nozzle assembly includes an outlet channel fixedly installed at the bottom of the graphite inner cylinder, and a detachable nozzle is installed at the outlet end of the outlet channel for extruding the pressurized molten aluminum alloy in the form of jet droplets.

[0007] Furthermore, the graphite inner cylinder is configured as a cylindrical cavity structure, and a cap is provided at the top of the graphite inner cylinder. The push rod passes through the cap and can move up and down inside the cap.

[0008] Furthermore, the feeding pipe, stirring pipe and graphite inner cylinder are integrally formed, the feeding pipe and stirring pipe are inclinedly arranged on both sides of the graphite inner cylinder, and the top of the feeding pipe is provided with a sealing cap.

[0009] Furthermore, a motor bracket is installed at the middle position of the outer frame support, and a stirring servo drive structure is fixedly installed on the motor bracket. The stirring servo drive structure includes a rotary drive mechanism and a linear feed mechanism. The linear feed mechanism includes a linear feed servo motor, a ball screw, a screw nut, a guide rail, and a sliding seat. The linear feed servo motor is fixedly mounted on a motor bracket. The ball screw is arranged along the axial direction of the stirring tube. The screw nut is fixedly connected to the sliding seat, and the sliding seat is slidably mounted on the guide rail. The rotary drive mechanism includes a rotary servo motor, a coupling, and a stirring rod connecting seat. The rotary servo motor is fixedly mounted on the sliding seat, and the output end of the rotary servo motor is connected to the stirring rod connecting seat through the coupling. The upper end of the stirring rod is fixedly mounted on the stirring rod connecting seat. When the linear feed servo motor drives the ball screw to rotate, the screw nut drives the sliding seat, the rotary drive mechanism, and the stirring rod to move axially along the stirring tube. When the rotary servo motor is working, it drives the stirring rod to rotate around its own axis.

[0010] Furthermore, the nozzle and the outlet channel are connected by a threaded connection or a snap-fit ​​connection to achieve detachable installation. The nozzle includes an intermediate pipe formed by multiple sets of arc-shaped tubes continuously surrounding each other. The intermediate pipe is annular in shape. One end of the intermediate pipe is connected to the upper pipe, and the other end of the intermediate pipe is connected to the lower pipe.

[0011] Furthermore, the additive manufacturing apparatus also includes an auxiliary heating component, which includes a movable support. The movable support is composed of three legs and a central column. The ends of the legs are provided with adjustable flat pads. The central column is a rod-shaped structure with adjustable height. A reflector mounting bracket is installed at the top of the column. A reflector is fixedly installed on the reflector mounting bracket. A dual-axis solar tracking mechanism is provided between the column and the reflector mounting bracket to realize the orientation and pitch adjustment of the reflector. An optical tracker is installed on the reflective mounting bracket. The optical tracker is located at the edge below the reflector, and an optical fiber mounting base is provided at the focal point of the reflector. The optical fiber mounting base is used to fix the receiving end of the multi-core optical fiber. In this configuration, the probe end of the optical tracker faces the focal region of the reflector, and the receiver end of the multi-core fiber is aligned with the focal point of the reflector.

[0012] Furthermore, the auxiliary heating component also includes a composite focusing lens, specifically including an aspherical collimating lens, a Fresnel lens, and an aspherical converging lens, used to refract and focus the sunlight beam; In this process, the divergent sunlight output from the multi-core fiber bundle passes through the aspherical collimating lens in the composite focusing lens to form a parallel beam. The collimated beam then passes through the Fresnel lens and the aspherical converging lens to form a real image spot with adjustable spot size and focusing position. Finally, the focused spot is projected onto the position of the aluminum alloy droplet forming for auxiliary heating.

[0013] Furthermore, the additive manufacturing apparatus also includes a molding platform assembly, which includes a three-dimensional moving structure and a preheating structure disposed on the three-dimensional moving structure; The three-dimensional moving structure includes a three-dimensional motion platform, which is driven by a ball screw guide rail in conjunction with a stepper motor to realize the on-demand movement of the overlap spacing, forming layer height and planned trajectory. The preheating structure includes a preheating platform installed on a three-dimensional moving structure. The preheating platform is equipped with a resistance heater, and a forming substrate is fixedly installed on the top of the preheating platform by bolts. Under the combined heating action of the auxiliary heating components and the preheating structure, the jet droplets are deposited, wetted, spread and solidified drop by drop on the forming substrate, and layer by layer to form a three-dimensional component.

[0014] Furthermore, the additive manufacturing apparatus includes an integrated control component, which employs a PLC controller or an embedded microcontroller.

[0015] According to a second aspect of the present invention, the present invention provides a method for additive manufacturing of lunar-based aluminum alloys, employing a lunar-based aluminum alloy additive manufacturing apparatus described in the first aspect, comprising the following steps: S1: Add an appropriate amount of smelted aluminum alloy product into the graphite inner cylinder through the feeding pipe, start the resistance heating wire for heating, and after the aluminum alloy melts, start the linear feed servo motor, which drives the sliding seat, rotary drive mechanism and stirring rod to insert into the graphite inner cylinder along the stirring tube axis through the ball screw and screw nut. After reaching the set working position, stop feeding, start the rotary servo motor, and drive the stirring rod to rotate at low speed around its own axis through the coupling and stirring rod connecting seat to achieve the homogenization of the composition of the molten aluminum alloy. S2: The rotary servo motor stops working, and the linear feed servo motor is started to rotate in the opposite direction. Through the ball screw, screw nut and sliding seat, the stirring rod is driven to exit the graphite inner cylinder along the stirring tube axis; the servo electric cylinder is activated to move it downward, and the push piston is moved to contact the aluminum alloy melt, the preheating structure is started, and the printing trajectory, motion parameters and working pressure parameters are preset in the integrated control component. S3: Connect the reflector to an unobstructed outdoor area with sunlight or the working area of ​​the solar simulator, and adjust the position and size of the focusing spot according to the falling position of the aluminum alloy jet droplets; S4: Start the servo electric cylinder and increase the pressure to the set value. After the jet droplets stabilize, turn on the composite focusing lens assembly and start the three-dimensional moving structure to complete the additive manufacturing process according to the set trajectory. S5: After the predetermined additive manufacturing process is completed, the servo electric cylinder retracts; the preheating structure stops heating, and the three-dimensional moving structure retracts to a safe position; the work stops after heating is stopped or the remaining aluminum alloy melt in the graphite inner cylinder is removed.

[0016] This invention has at least the following beneficial effects: 1. This invention employs a servo-driven electric cylinder-based mechanical propulsion system to replace the traditional pneumatic drive, completely eliminating the reliance on high-pressure gas. The propulsion piston directly applies mechanical pressure to the molten aluminum alloy within the graphite inner cylinder, forcing the melt to be extruded from the nozzle to form jet droplets. This solves the inherent defects of the lack of gas medium and the complexity and easy leakage of pneumatic drive systems in the high vacuum environment of the lunar surface, enabling the device to operate stably and reliably in a vacuum environment. Simultaneously, the dynamic sealing fit between the cap at the top of the graphite inner cylinder and the propulsion rod, along with the integrated feeding tube and stirring tube structure, together construct a sealed melting cavity, effectively preventing melt evaporation and leakage, further improving operational reliability in a vacuum environment.

[0017] 2. This invention employs an auxiliary heating scheme that uses a reflector to focus sunlight, a multi-core fiber for flexible transmission, and a composite focusing lens to precisely deliver concentrated heat. This replaces the high-energy-consuming heat sources commonly used in terrestrial additive manufacturing, such as lasers, electron beams, and electric arcs. This design fully utilizes the abundant solar energy resources on the lunar surface, using free, clean, and sustainable solar energy as a secondary heating energy source. This significantly reduces reliance on high-power electrical energy supply and effectively alleviates the power supply pressure on the lunar energy system. At the same time, the resistance heater built into the preheating platform uses electric heating, complementing the solar concentrating heating: concentrating heating meets the needs for high-intensity, localized instantaneous heating, while resistance heating meets the needs for continuous, large-area basic heating. The two work together to achieve optimized energy allocation and precise control of the thermal field, constructing a highly efficient energy utilization system adapted to the characteristics of lunar energy supply.

[0018] 3. The preheating platform of this invention actively preheats the substrate, eliminating the chilling effect that may be caused by the extreme low temperature environment on the lunar surface, and creating thermodynamic conditions for the initial wetting and spreading of the molten droplets; the auxiliary heating component performs secondary heating on the aluminum alloy droplets and the surface of the deposited layer, improving the spreading behavior of the droplets in a weak gravity and large temperature difference environment, and promoting interlayer metallurgical bonding; the stirring mechanism homogenizes the melt, reduces the risk of porosity formation and mitigates component segregation, and improves the purity of the melt. The synergistic effect of the dual heat sources combined with the melt pretreatment effectively suppresses typical additive manufacturing defects such as porosity, cracks, lack of fusion, and spheroidization, significantly improving the density, mechanical properties and dimensional accuracy of the formed components, laying the foundation for manufacturing high-quality structural components on the lunar surface.

[0019] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0020] Figure 1 This is a cross-sectional view of the overall structure of the present invention; Figure 2 This is a side sectional view of the overall structure of the present invention; Figure 3 This is a three-dimensional schematic diagram of the auxiliary heating component structure of the present invention; Figure 4 This is a three-dimensional schematic diagram of the nozzle structure of the present invention.

[0021] Figure label: 1. Graphite inner cylinder; 2. Feeding tube; 3. Resistance heating wire; 4. Alumina ceramic tube; 5. Alumina fiber insulation layer; 6. Outer frame support; 7. Stirring tube; 8. Stirring rod; 9. Stirring servo drive structure; 10. Motor support; 11. Propulsion piston; 12. Propulsion rod; 13. Servo electric cylinder; 14. Outlet channel; 15. Nozzle; 16. Moving support; 17. Reflector; 18. Optical tracker; 19. Multi-core optical fiber; 20. Composite focusing lens; 21. Three-dimensional moving structure; 22. Preheating structure. Detailed Implementation

[0022] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0023] Example 1: Please see Figures 1-3 This invention provides a technical solution: a lunar-based aluminum alloy additive manufacturing apparatus, comprising a heating and bearing assembly, a stirring assembly, an injection assembly, an extrusion nozzle assembly, and an auxiliary heating assembly, wherein: The heating support assembly includes an outer frame support 6, a graphite inner cylinder 1 installed in the middle of the outer frame support 6, and a feeding pipe 2 installed on the upper part of the graphite inner cylinder 1. The feeding pipe 2 is connected to the graphite inner cylinder 1 and is used to add aluminum alloy raw materials into the graphite inner cylinder 1. In response to the above solution, this embodiment uses a graphite inner cylinder 1 as a melting container, making full use of the excellent high-temperature resistance, good thermal conductivity and excellent thermal shock resistance of graphite material. It can withstand the large temperature difference cycle on the lunar surface and the severe thermal shock during the aluminum alloy melting process, ensuring the reliability of long-term use. A resistance heating wire 3 is wound around the outside of the graphite inner cylinder 1. The resistance heating wire 3 is directly wound around the outside of the graphite inner cylinder 1. Heat is uniformly conducted through the graphite body, realizing direct and efficient heating of aluminum alloy raw materials. This avoids complex heat conduction paths and can melt coarse aluminum alloy raw materials with different particle sizes and morphologies, significantly improving the adaptability to in-situ smelting products on the lunar surface. An alumina ceramic tube 4 and an alumina fiber insulation layer 5 are sequentially fitted on the outside of the graphite inner cylinder 1 to form a composite heat insulation structure, which is used for heat insulation and heat preservation of the graphite inner cylinder 1, respectively. By utilizing the high temperature resistance and support characteristics of ceramics and the low thermal conductivity of fiber materials, heat loss to the outside is effectively reduced in a vacuum environment. This not only significantly reduces the power consumption required to maintain the molten state, but also prevents the thermal impact of high temperature on external mechanisms and the lunar surface environment.

[0024] Regarding the technical solution of this embodiment, a motor bracket 10 is installed in the middle of the outer frame bracket 6. A stirring servo drive structure 9 is fixedly installed on the motor bracket 10. The stirring servo drive structure 9 is connected to the stirring rod 8 through a linear feed mechanism and a rotary drive mechanism. The linear feed mechanism includes a linear feed servo motor, a ball screw, a screw nut, a guide rail, and a sliding seat. The linear feed servo motor is fixedly installed on the motor bracket 10. The ball screw is arranged along the axial direction of the stirring tube 7. The screw nut is fixedly connected to the sliding seat. The sliding seat is slidably installed on the guide rail. When the linear feed servo motor is started, the ball screw and screw nut drive the sliding seat, the rotary drive mechanism, and the stirring rod to insert into the graphite inner cylinder along the axial direction of the stirring tube. The feeding stops after reaching the set working position. The rotary drive mechanism includes a rotary servo motor, a coupling, and a stirring rod connecting seat. The rotary servo motor is fixedly mounted on the sliding seat, and the output end of the rotary servo motor is connected to the stirring rod connecting seat through the coupling. The upper end of the stirring rod 8 is fixedly mounted on the stirring rod connecting seat. When the linear feed servo motor drives the ball screw to rotate, the screw nut drives the sliding seat, the rotary drive mechanism, and the stirring rod 8 to move axially along the stirring tube 7. The rotary servo motor is started, and the stirring rod is driven to rotate at low speed around its own axis through the coupling and the stirring rod connecting seat. This is used to drive the stirring rod 8 to rotate around its own axis and move axially along the stirring tube 7, which is used to stir and homogenize the molten aluminum alloy in the graphite inner cylinder 1. In this embodiment, the stirring tube 7 is fixedly mounted on the upper part of the graphite inner cylinder 1, providing precise guidance and stable support for the stirring rod 8, ensuring that the stirring rod 8 can accurately extend into the core area of ​​the molten pool, while avoiding the thermal impact of the high-temperature melt on the upper drive mechanism. Secondly, the stirring rod 8 is connected to the graphite inner cylinder 1 through the stirring tube 7 and rotates inside the molten aluminum alloy. The rotation of the stirring rod 8 generates a shearing effect in the melt, which can promote the coalescence and escape of gases entrained or generated during the melting process, significantly reducing the gas content in the melt. This effectively suppresses the formation of metallurgical defects such as porosity and looseness in the subsequent printed components, laying the foundation for improving the density and mechanical properties of the formed parts.

[0025] The injection assembly includes a push piston 11 that is slidably connected inside the graphite inner cylinder 1. A push rod 12 is mounted on the top of the push piston 11. A servo electric cylinder 13 is mounted above the push rod 12. The servo electric cylinder 13 is mounted on the top of the outer frame bracket 6. The servo electric cylinder 13 drives the push rod 12 to move, thereby controlling the displacement of the push piston 11 inside the graphite inner cylinder 1. In response to the above solution, this embodiment uses a servo electric cylinder 13 as a power source to achieve mechanical pressure establishment and precise control. The servo electric cylinder 13 converts the rotational motion into the linear motion of the push rod 12 through the lead screw, which can accurately control the displacement speed and position of the push piston 11, thereby applying a stable and adjustable extrusion pressure to the molten aluminum alloy. This design completely eliminates the dependence of traditional pneumatic drive on high-pressure gas, fundamentally solving the fatal defects of gas medium being unusable and gas delivery system being complex and prone to leakage in the high vacuum environment of the lunar surface, ensuring the absolute reliability of the feeding system in a vacuum environment. It should be noted that in this embodiment, a worm gear reducer can also be used instead of a ball screw. A servo electric cylinder drives the worm to rotate, and the worm gear drives a coaxial gear or a directly connected push rod 12 (via a rack and pinion mechanism) to achieve linear propulsion. The worm gear mechanism has the advantages of a large reduction ratio and significant self-locking characteristics. After power failure, the push piston 11 can automatically lock in its current position to prevent molten material backflow or accidental dripping, thus improving system safety. However, the worm gear transmission efficiency is relatively low, and the lubrication requirements are high. In the vacuum environment of the lunar surface, solid lubrication or special grease lubrication schemes are required.

[0026] The extrusion nozzle assembly includes an outlet channel 14 fixedly installed at the bottom of the graphite inner cylinder 1, and a nozzle 15 is detachably installed at the outlet end of the outlet channel 14 for extruding the pressurized molten aluminum alloy in the form of jet droplets. In response to the above-mentioned solution, this embodiment designates the flow channel 14 as a passage for the molten aluminum alloy to transition from the graphite inner cylinder 1 to the nozzle 15, playing a crucial role in stabilizing the flow field and accumulating pressure. When the melt flows within the flow channel, the geometric constraints of the flow channel cross-section and the wall friction consume the turbulent kinetic energy that may be generated by the extrusion of the propulsion piston 11, transforming the melt from a disordered flow state to an ordered and stable laminar flow state, laying the fluid dynamics foundation for the subsequent formation of uniform and continuous jet droplets. Secondly, the nozzle 15 adopts a detachable installation structure (such as a threaded + snap-fit ​​combination), which gives the equipment a strong process adaptability. Lunar manufacturing tasks are diverse, which may require the rapid printing of large-sized components (requiring large-diameter nozzle 15 and high extrusion flow rate) or the fine forming of complex structures (requiring small-diameter nozzle 15 and high-precision droplet). The detachable design allows operators to quickly change nozzles 15 with different apertures and materials on the lunar surface according to specific task requirements.

[0027] Regarding the technical solution of this embodiment, the outlet channel 14 and the nozzle 15 are connected by threads and locked with a snap-fit ​​mechanism to achieve detachable installation. The nozzle 15 adopts a continuously alternating, circumferentially curved structure with a 0.5mm cylindrical through hole in the middle. The nozzle 15 includes a central pipe formed by multiple sets of continuously circumferentially curved arc-shaped tubes. The central pipe is annular in shape, with one end connected to an upper pipe and the other end connected to a lower pipe. Figure 4 As shown.

[0028] Regarding the technical solution of this embodiment, the graphite inner cylinder 1 is configured as a cylindrical cavity structure, and a cover is provided at the top of the graphite inner cylinder 1. The push rod 12 passes through the cover and can move up and down inside the cover. Specifically, the cap acts as a thermal barrier at the top of the graphite inner cylinder 1, effectively blocking the upward radiation and convection of heat from the molten pool. Together with the insulation layer of the cylinder wall, it forms a fully enclosed insulation system, ensuring that the heat generated by the resistance heating wire 3 is confined to the molten cavity to the maximum extent for melting the raw materials; Furthermore, the cap is equipped with a guide hole that precisely matches the push rod 12, providing stable support and precise guidance for the reciprocating motion of the push rod 12. This design ensures that the push piston 11 always moves vertically along the axis within the graphite inner cylinder 1, avoiding jamming, uneven wear, or melt leakage caused by piston misalignment. At the same time, the fit clearance between the push rod 12 and the guide hole of the cap has been optimized, minimizing the overflow of molten volatiles and heat loss while ensuring smooth movement, thus achieving effective sealing under dynamic operating conditions.

[0029] Regarding the technical solution of this embodiment, the feeding pipe 2, stirring pipe 7, and graphite inner cylinder 1 are integrally formed, completely eliminating potential leakage paths such as welds, threads, or flange connections in traditional split designs. In the high vacuum environment of the lunar surface, any tiny gap may lead to the leakage of molten pool volatiles or the intrusion of external ultra-low pressure gas, which could disrupt the stability of the melt. The integrally formed structure fundamentally eliminates the risk of leakage, ensures the airtightness of the molten cavity, and creates a fundamental prerequisite for the stable existence of the melt in a vacuum environment. The feeding pipe 2 and the stirring pipe 7 are inclinedly arranged on both sides of the graphite inner cylinder 1, and the top of the feeding pipe 2 is equipped with a sealing cap. The inclined angle design makes full use of the characteristics of the weak gravity environment on the moon: the inclination of the feeding pipe 2 is conducive to the raw material sliding into the molten pool by relying on weak gravity, reducing the possibility of raw material accumulating or bridging on the pipe wall, and improving the smoothness of feeding; the inclination of the stirring pipe 7 allows the stirring rod 8 to cut into the molten pool at the optimal angle, forming a more effective three-dimensional convection flow field when rotating and stirring, avoiding the stirring dead zone that may be generated by vertical insertion. The symmetrical inclined layout on both sides also balances the overall center of gravity of the equipment, making the graphite inner cylinder 1 uniformly stressed, and reducing the risk of deformation of the sealing surface or wear of moving parts due to uneven loading.

[0030] Regarding the technical solution of this embodiment, the additive manufacturing apparatus further includes an auxiliary heating component. The auxiliary heating component includes a movable support 16, which is composed of three legs and a central column. The ends of the legs are provided with adjustable flat pads. The central column is a rod-shaped structure with adjustable height. A reflective mounting bracket is installed at the top of the column. A reflector 17 is fixedly installed on the reflective mounting bracket. A dual-axis solar tracking mechanism is provided between the column and the reflective mounting bracket to realize the orientation and pitch adjustment of the reflector 17. In the natural environment of the lunar surface, the terrain is uneven, rocks are scattered, and lunar soil is soft. The tripod structure can adaptively contact three high points and automatically form a stable support plane, avoiding the suspension and swaying problems that inevitably exist for four-legged or multi-legged structures on uneven ground. The adjustable flat pads at the end of each leg can rotate to adjust the height according to the actual terrain, further compensating for local terrain undulations, so that the central column can be precisely adjusted to a vertical state, providing a stable reference platform for subsequent optical solar tracking; The dual-axis solar tracking mechanism installed between the top of the column and the reflector mounting frame is a two-degree-of-freedom active tracking mechanism for adjusting the attitude of the reflector 17. Through the coordinated movement of the azimuth and pitch axes, the reflector 17 can achieve rotation in the azimuth direction and precise oscillation in the pitch direction, meeting the real-time pointing adjustment requirements of the reflector 17 during solar tracking. The dual-axis solar tracking mechanism can use a rotary actuator to achieve azimuth adjustment and a linear actuator to achieve altitude adjustment. With the feedback signal output from the optical tracker 18, the attitude of the reflector 17 is controlled in a closed loop, thereby ensuring that the receiving end of the multi-core fiber 19 is continuously aligned with the focal position of the reflector 17, improving the stability of sunlight convergence and coupling transmission. The dual-axis solar tracking mechanism has the characteristics of compact structure, high adjustment accuracy, timely response and reliable locking. With the help of the braking or locking mechanism, it can achieve rigid holding after adjustment, ensuring that the reflector 17 maintains stable pointing under equipment operation vibration and lunar surface environmental disturbances. In the vacuum environment of the lunar surface, the rotary joints, articulated joints and transmission components of the dual-axis solar tracking mechanism can adopt self-lubricating materials, solid lubricating coatings or vacuum-adaptive transmission structures to achieve maintenance-free and long-term reliable operation. Among them, the optical tracker 18 is parallel to the center of the mirror surface of the reflector 17 and is used to sense the solar incident deviation in real time, providing feedback signals for the attitude adjustment of the reflector 17. The receiving end of the multi-core fiber 19 is aligned with the focal point of the reflector 17 and is used to receive the solar energy gathered by the reflector 17 and transmit the solar energy to external devices through the fiber optic cable. An optical tracker 18 is mounted on the reflector mounting bracket. The optical tracker 18 is located at the lower edge of the reflector 17, and an optical fiber mounting base is set at the focal position of the reflector 17. The receiving end of the multi-core optical fiber 19 is fixedly mounted on the optical fiber mounting base. By mounting the tracker below the reflector 17 rather than directly in front of or above it, its detection field of view completely avoids the obstruction of the reflector 17 itself, and it can directly observe the true position of the sun in the sky. In the vacuum environment of the moon surface without atmospheric scattering, the outline of the sun is sharp and the background starry sky is dark. The tracker can accurately calculate the sun's azimuth and pitch angle in real time based on the principle of solar imaging or four-quadrant light intensity balance, and provide a high-precision feedback signal for the pointing adjustment of the reflector 17. The parabolic surface of reflector 17 focuses parallel sunlight to its focal point, forming a focal spot with extremely high energy density. By precisely fixing the fiber optic mount at this focal position, and ensuring that the receiving end face of the multi-core fiber 19 is directly facing the center of the focal spot, maximum coupling reception of concentrated solar energy is achieved.

[0031] Regarding the technical solution of this embodiment, the auxiliary heating component also includes a composite focusing lens 20, specifically including an aspherical collimating lens, a Fresnel lens, and an aspherical converging lens, used to achieve the refraction and focusing of the sunlight beam; Among them, the composite focusing lens 20 collimates, focuses and shapes the diverging sunlight output from the end of the multi-core fiber 19, realizes the adjustment of the spot size and focusing position, and finally projects the focused spot onto the position of the aluminum alloy droplet forming for auxiliary heating.

[0032] Regarding the technical solution of this embodiment, the additive manufacturing apparatus further includes a molding platform assembly, which includes a three-dimensional moving structure 21 and a preheating structure 22 disposed on the three-dimensional moving structure 21; The three-dimensional moving structure 21 includes a three-dimensional motion platform, which is driven by a ball screw guide rail and a stepper motor to realize the on-demand movement of the overlap spacing, forming layer height and planned trajectory. Specifically, in the vacuum environment of the lunar surface, traditional sliding guides may become sticky or wear due to a lack of lubricant, while ball screws can use solid lubricating coatings or self-lubricating materials to maintain smooth rolling, ensuring long-term operational reliability and stable motion accuracy. As a support and guiding element, the guide rail provides a highly rigid motion reference for the three-dimensional motion platform, enabling it to maintain its predetermined trajectory even when subjected to external forces such as molten droplet impacts and cable drag chain tension. The combination of ball screw and stepper motor enables precise reproduction of overlap spacing, layer height, and planned trajectory. Additive manufacturing demands extremely high precision in motion trajectory: the accuracy of overlap spacing determines the bonding quality between adjacent melt channels, layer height accuracy determines Z-axis dimensional accuracy and interlayer bonding strength, and trajectory reproduction accuracy determines the fit between the component contour and the design model. This three-dimensional moving structure 21 can precisely execute the scanning path of each layer according to preset parameters, ensuring that the molten droplet is deposited at the designated position, laying the kinematic foundation for high-precision forming. In addition, the structure has sufficient rigidity and load-bearing capacity. The three-dimensional motion structure 21 needs to support the preheating structure, the forming substrate, and the growing components. As the height of the components increases, the load mass gradually increases. The high rigidity of the ball screw guide pair ensures that the motion accuracy can be maintained under different load conditions, avoiding trajectory deviation or vibration caused by load changes, and ensuring the stability of the forming process.

[0033] The preheating structure 22 includes a preheating platform installed on the three-dimensional moving structure 21. The preheating platform is equipped with a resistance heater, and a forming substrate is fixedly installed on the top of the preheating platform by bolts. Under the heating action of the auxiliary heating component and the resistance heater, the jet molten droplets are deposited, wetted, spread and solidified drop by drop on the forming substrate, and the three-dimensional components are formed layer by layer. The preheating platform incorporates a built-in resistance heater, enabling active preheating and temperature control of the substrate. In the extreme low-temperature environment of the lunar surface (down to -100 degrees Celsius in the shadow region), if molten aluminum alloy is directly dripped onto the cold substrate, the melt will rapidly solidify, failing to adequately wet and spread, leading to spheroidization, poor interlayer bonding, or even forming failure. The preheating platform actively heats the substrate through its built-in resistance heater, raising the substrate temperature to a suitable range for aluminum alloy spreading, thus creating the thermodynamic conditions for initial wetting of the molten droplet.

[0034] Regarding the technical solution of this embodiment, the additive manufacturing apparatus also includes an integrated control component, which is used to control the heating, melting and heat preservation process of aluminum alloy, the propulsion extrusion process, the auxiliary heating process and the movement process of the three-dimensional motion platform. It mainly consists of a multi-functional electrical control box component and a control software component. The multi-functional electrical control box component includes a sensor unit, a motion control unit, and a main control unit, which mainly realizes the power supply and distribution of various sensors, heating devices, and moving devices; the system control software component, through human-computer interaction units such as temperature control adjustment, pressure setting, and motion trajectory planning, mainly realizes closed-loop control of heating temperature, coordinated control of propulsion pressure and displacement, and planning of motion path.

[0035] It should be noted that the integrated control components can also use radiation-hardened PLC controllers (programmable logic controllers) or embedded microcontrollers to improve operational reliability in the strong radiation environment of the lunar surface. Radiation-hardened PLC controllers enhance their adaptability to single-event and total dose effects through radiation-resistant components, shielding design, and redundant control strategies, ensuring long-term stable operation of the control system without maintenance. Their modular structure allows for independent replacement of the power supply module, CPU module, and I / O module, enabling rapid repair via spare modules during lunar base construction. Embedded microcontrollers integrate the CPU, memory, and various interfaces onto a single chip, resulting in extremely low power consumption and high integration. Given that lunar energy relies primarily on solar power and power supply is relatively tight, low power consumption translates to less energy consumption and longer continuous operating time. Simultaneously, high integration allows for smaller and lighter control circuit boards, reducing the overall launch mass and size of the additive manufacturing apparatus and improving transportation efficiency.

[0036] Example 2: This embodiment provides a lunar-based aluminum alloy additive manufacturing method, using a lunar-based aluminum alloy additive manufacturing apparatus described in Embodiment 1, and includes the following steps: S1: Add an appropriate amount of smelted aluminum alloy product to the graphite inner cylinder 1 through the feeding pipe 2, start the resistance heating wire 3 to heat it, and after the aluminum alloy melts, drive the stirring rod 8 to be placed into the graphite inner cylinder 1 to stir the molten aluminum alloy and achieve uniformity of the composition of the molten aluminum alloy. S2: Remove the stirring rod 8, activate the servo electric cylinder 13 to extend it, move the push piston 11 to contact the aluminum alloy melt, start the preheating structure 22, and preset the printing trajectory, motion parameters, and working pressure parameters in the integrated control component; S3: Connect the reflector 17 to an unobstructed outdoor area with sunlight or the working area of ​​the solar simulator, and adjust the position and size of the focusing spot according to the falling position of the aluminum alloy jet droplets; S4: Start the servo electric cylinder 13 and increase the pressure to the set value. After the jet droplets stabilize, turn on the composite focusing lens 20 component and start the three-dimensional moving structure 21 to complete the additive manufacturing process according to the set trajectory. S5: After the predetermined additive manufacturing process is completed, the servo electric cylinder 13 retracts; the preheating structure 22 stops heating, and the three-dimensional moving structure 21 retracts to a safe position; the work stops after heating is stopped or the remaining aluminum alloy melt in the graphite inner cylinder 1 is removed.

[0037] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0038] For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances. When an element is referred to as being "assembled on," "mounted on," "fixed to," or "set on" another element, it may be directly on the other element or there may be an intermediate element present. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible embodiments.

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0040] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

Claims

1. A lunar-based aluminum alloy additive manufacturing apparatus, characterized in that, It includes a heating support assembly, a stirring assembly, an injection assembly, and an extrusion nozzle assembly, wherein: The heating support assembly includes an outer frame support (6), a graphite inner cylinder (1) is installed in the middle of the outer frame support (6), a feeding pipe (2) is installed on the upper part of the graphite inner cylinder (1), the feeding pipe (2) is connected to the graphite inner cylinder (1) and is used to add aluminum alloy raw materials into the graphite inner cylinder (1); a resistance heating wire (3) is wound around the outside of the graphite inner cylinder (1), and an alumina ceramic tube (4) and an alumina fiber insulation layer (5) are sequentially sleeved on the outside of the graphite inner cylinder (1); The stirring assembly includes a stirring tube (7) fixedly installed on the upper part of the graphite inner cylinder (1), and a stirring rod (8) is rotatably arranged inside the stirring tube (7). The stirring rod (8) extends into the graphite inner cylinder (1) through the stirring tube (7). The injection assembly includes a thrust piston (11) slidably connected inside the graphite inner cylinder (1), a thrust rod (12) is installed on the top of the thrust piston (11), a servo electric cylinder (13) is provided above the thrust rod (12), and the servo electric cylinder (13) is installed on the top of the outer frame bracket (6). The extrusion nozzle assembly includes an outlet channel (14) fixedly installed at the bottom of the graphite inner cylinder (1), and a detachable nozzle (15) is installed at the outlet end of the outlet channel (14) for extruding the pressurized molten aluminum alloy in the form of jet droplets.

2. The lunar-based aluminum alloy additive manufacturing apparatus according to claim 1, characterized in that: The graphite inner cylinder (1) is configured as a cylindrical cavity structure, and a cover is provided at the top of the graphite inner cylinder (1). The push rod (12) passes through the cover and can push the piston (11) to move up and down inside the cover.

3. The lunar-based aluminum alloy additive manufacturing apparatus according to claim 2, characterized in that: The feeding pipe (2) and stirring pipe (7) are integrally formed with the graphite inner cylinder (1). The feeding pipe (2) and stirring pipe (7) are arranged obliquely on both sides of the graphite inner cylinder (1), and a sealing cap is provided on the top of the feeding pipe (2).

4. The lunar-based aluminum alloy additive manufacturing apparatus according to claim 2, characterized in that: A motor bracket (10) is installed in the middle of the outer frame bracket (6), and a stirring servo drive structure (9) is fixedly installed on the motor bracket (10). The stirring servo drive structure (9) includes a rotary drive mechanism and a linear feed mechanism. The linear feed mechanism includes a linear feed servo motor, a ball screw, a screw nut, a guide rail, and a sliding seat. The linear feed servo motor is fixedly mounted on the motor bracket (10). The ball screw is arranged along the axial direction of the stirring tube (7). The screw nut is fixedly connected to the sliding seat, and the sliding seat is slidably mounted on the guide rail. The rotary drive mechanism includes a rotary servo motor, a coupling, and a stirring rod connecting seat. The rotary servo motor is fixedly mounted on the sliding seat, and the output end of the rotary servo motor is connected to the stirring rod connecting seat through the coupling. The upper end of the stirring rod (8) is fixedly mounted on the stirring rod connecting seat. When the linear feed servo motor drives the ball screw to rotate, the screw nut drives the sliding seat, the rotary drive mechanism, and the stirring rod (8) to move axially along the stirring tube (7). When the rotary servo motor is working, it drives the stirring rod (8) to rotate around its own axis.

5. The lunar-based aluminum alloy additive manufacturing apparatus according to claim 4, characterized in that: The nozzle (15) and the outlet channel (14) are connected by thread or snap-fit ​​to achieve detachable installation. The nozzle (15) includes an intermediate pipe formed by multiple sets of arc-shaped tubes continuously surrounding each other. The intermediate pipe is annular in shape. One end of the intermediate pipe is connected to the upper pipe, and the other end of the intermediate pipe is connected to the lower pipe.

6. The lunar-based aluminum alloy additive manufacturing apparatus according to claim 4, characterized in that: It also includes an auxiliary heating component, which includes a movable support. The movable support is composed of three legs and a central column. The ends of the legs are provided with adjustable flat pads. The central column is a rod-shaped structure with adjustable height. A reflector mounting bracket is installed at the top of the column. A reflector (17) is fixedly installed on the reflector mounting bracket. A dual-axis solar tracking mechanism is provided between the column and the reflector mounting bracket to realize the orientation and pitch adjustment of the reflector (17). An optical tracker (18) is installed on the reflector mounting bracket. The optical tracker (18) is located at the edge below the reflector (17). An optical fiber mounting base is provided at the focal position of the reflector (17). The receiving end of the multi-core optical fiber (19) is fixedly installed on the optical fiber mounting base. The optical tracker (18) has its probe end facing the focal region of the reflector (17), and the receiver end of the multi-core fiber (19) is aligned with the focal point of the reflector (17).

7. The lunar-based aluminum alloy additive manufacturing apparatus according to claim 6, characterized in that: The auxiliary heating component also includes a composite focusing lens (20), specifically including an aspherical collimating lens, a Fresnel lens, and an aspherical converging lens, used to achieve the refraction and focusing of the sunlight beam; Among them, the divergent sunlight output by the multi-core fiber bundle (19) is formed into a parallel beam by the aspherical collimating lens in the composite focusing lens (20). The collimated beam is formed into a real image spot by the Fresnel lens and the aspherical converging lens, and finally the focused spot is projected onto the position of the aluminum alloy droplet forming for auxiliary heating.

8. The lunar-based aluminum alloy additive manufacturing apparatus according to claim 6, characterized in that: It also includes a molding platform assembly, which includes a three-dimensional moving structure (21) and a preheating structure (22) disposed on the three-dimensional moving structure (21); The three-dimensional moving structure (21) includes a three-dimensional motion platform, which is driven by a ball screw guide rail in conjunction with a stepper motor to realize the on-demand movement of the overlap spacing, forming layer height and planned trajectory. The preheating structure (22) includes a preheating platform installed on the three-dimensional moving structure (21). The preheating platform is equipped with a resistance heater, and a forming substrate is fixedly installed on the top of the preheating platform by bolts. Under the combined heating action of the auxiliary heating component and the preheating structure (22), the jet molten droplets are deposited, wetted, spread and solidified drop by drop on the forming substrate, and layer by layer are accumulated to form a three-dimensional component.

9. The lunar-based aluminum alloy additive manufacturing apparatus according to claim 8, characterized in that: It also includes an integrated control component, which employs a PLC controller or an embedded microcontroller.

10. A method for additive manufacturing of lunar-based aluminum alloys, using the lunar-based aluminum alloy additive manufacturing apparatus according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1: Add an appropriate amount of smelted aluminum alloy product to the graphite inner cylinder (1) through the feeding pipe (2), start the resistance heating wire (3) for heating, and after the aluminum alloy melts, start the linear feed servo motor, drive the sliding seat, rotary drive mechanism and stirring rod to insert into the graphite inner cylinder along the stirring tube axis through the ball screw and screw nut, stop feeding after reaching the set working position, start the rotary servo motor, drive the stirring rod to rotate slowly around its own axis through the coupling and stirring rod connecting seat, so as to achieve the homogenization of the composition of the molten aluminum alloy; The tilting stirring mechanism includes a stirring rod (8) and a stirring servo drive structure (9). The stirring servo drive structure (9) has a rotary-linear composite execution capability. The linear feed mechanism of the stirring servo drive structure (9) drives the stirring rod (8) to insert into the graphite inner cylinder (1) along a preset tilt direction through a lead screw. After reaching the set working position, the feed stops. The rotary drive mechanism of the stirring servo drive structure (9) drives the stirring rod to rotate slowly around its own axis to achieve homogenization of the composition of the molten aluminum alloy. S2: The rotary servo motor stops working, and the linear feed servo motor is started to rotate in the opposite direction. Through the ball screw, screw nut and sliding seat, the stirring rod is driven to exit the graphite inner cylinder along the stirring tube axis. The servo electric cylinder (13) is activated to move it downward, and the push piston (11) is moved to contact the aluminum alloy melt. The preheating structure (22) is started, and the printing trajectory, motion parameters and working pressure parameters are preset in the integrated control component. S3: Connect the reflector (17) to an outdoor area with unobstructed sunlight or the working area of ​​the solar simulator, and adjust the position and size of the focusing spot according to the falling position of the aluminum alloy jet droplets; S4: Start the servo electric cylinder (13) and increase the pressure to the set value. After the jet droplets stabilize, turn on the composite focusing lens (20) assembly and start the three-dimensional moving structure (21) to complete the additive manufacturing process according to the set trajectory. S5: After the predetermined additive manufacturing process is completed, the servo electric cylinder (13) retracts; the preheating structure (22) stops heating, and the three-dimensional moving structure (21) retracts to a safe position; the work stops after heating is stopped or the remaining aluminum alloy melt in the graphite inner cylinder (1) is removed.

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