Compact phase change heat storage honeycomb structure heterogeneous metal microdroplet interactive printing forming method

Abstract

The invention discloses a compact phase change heat storage honeycomb structure heterogeneous metal microdroplet interactive printing forming method, and belongs to the field of metal additive manufacturing. According to the method, the characteristic that aluminum alloy and a phase-change material are a solubility gap system is utilized, a micro-droplet interactive printing forming method is adopted, and aluminum alloy micro-droplets and phase-change metal micro-droplet double nozzles are controlled to conduct collaborative printing by designing a honeycomb structure and planning a printing track, so that alternate deposition and space integration of a structural material and the phase-change material are achieved; therefore, the compact honeycomb metal phase change heat storage structure is prepared. Compared with a traditional method, the method has the advantages that high-density integrated printing forming of the aluminum alloy and the phase change metal heterostructure can be achieved without reserving a flow channel, an exhaust hole and a packaging auxiliary structure, the manufacturing process is simplified, meanwhile, the compactness and the overall sealing performance of the heat storage structure are remarkably improved, and the manufacturing cost is reduced. The problem of high-heat-flux heat management in a narrow space is solved.

Description

Technical Field

[0001] The present invention belongs to the field of metal additive manufacturing, and specifically relates to a method for interactively printing and forming heterogeneous metal droplets of a compact phase-change heat storage honeycomb structure. The method utilizes interactive printing of heterogeneous metal droplets of aluminum alloy and tin-bismuth alloy to form a compact honeycomb metal phase-change heat storage structure. Background Art

[0002] With the rapid development of tiny remote sensing satellites, high-speed aircraft, and miniaturized intelligent communication equipment, the power density and heat flux of equipment have increased significantly. However, due to the limited installation space and harsh external environment, the thermal control problem of intelligent equipment is becoming increasingly severe. High-throughput transient heat dissipation and storage has become a key bottleneck restricting the performance improvement of information equipment. To this end, it is urgent to develop more advanced compact phase change heat storage structures to achieve instantaneous absorption and storage of high heat flux density, alleviate temperature rise, maintain system temperature stability, and meet the challenges of high heat flux density and limited installation space.

[0003] Existing metal phase-change heat storage structures are mostly manufactured using the method of "infusing phase-change materials after structural formation." That is, the preparation of the metal box is separated from the filling process of the phase-change metal material. The box is first formed and sealed through processes such as machining and casting, and then filled with phase-change metal. Finally, the box is encapsulated by brazing to form a heat storage structure. Due to the need to reserve infusion channels and packaging structures, this type of method generally has problems such as large box volume, low structural density and complexity, and leakage risks. At present, the use of advanced additive manufacturing methods such as selective laser melting (SLM) can reduce the volume of the box and increase the complexity of forming, but it still has limitations in the coordinated deposition of materials, and still requires subsequent filling with phase-change metal and brazing packaging. The above methods are difficult to meet the manufacturing needs of metal phase-change heat storage structures with compact structures, high heat storage efficiency, and fast response speed in small spaces.

[0004] In the paper “C. Hu, H. Li, D. Tang, J. Zhu, K. Wang, X. Hu, M. Bai, Pore-scale investigation on the heat-storage characteristics of phase change material in graded copper foam, Appl. Therm. Eng. 2020, 178: 115609”, the researchers designed and manufactured a copper foam skeleton with a porosity gradient transition as a high thermal conductivity skeleton material, and then filled it with a paraffin-based phase change material (PCM). The heat storage performance of the paraffin-based phase change metal (PCM) was improved by designing the porosity gradient of the skeleton material. This method shows that by optimizing the structural distribution of metal pores, the full melting time of the phase change metal can be shortened and the average heat storage rate can be increased. Although this type of structure realizes the positive effect of a high thermal conductivity porous skeleton on phase change thermal management, it is still necessary to preform the metal foam frame and then infuse the liquid phase change metal into it. This type of phase change heat storage structure still has the problems of large overall volume, difficulty in sealing, uneven filling and cavity, which limits the application of phase change heat storage structure in small space scenarios.

[0005] Therefore, it is necessary to provide a compact phase change heat storage honeycomb structure heterogeneous metal droplet interactive printing molding method to solve the above problems. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, the present invention provides a method for interactively printing heterogeneous metal droplets to form a compact phase-change heat storage honeycomb structure. By utilizing the solubility gap between aluminum alloy (structural material) and phase-change material (phase-change material) (they do not melt together below the solidus), this method employs interactive droplet printing to achieve alternating deposition and spatial integration of the structural and phase-change materials, thereby fabricating a compact honeycomb metal phase-change heat storage structure. This method overcomes the existing challenges of conventional methods for fabricating metal phase-change heat storage structures, which involve separate steps for structural material preparation and phase-change material filling, followed by subsequent packaging. This method results in a complex manufacturing process, resulting in a bulky, poorly compact, and airtight product, making it unsuitable for high-heat-flux thermal management in confined spaces.

[0007] The technical solution of the present invention is: a compact phase change heat storage honeycomb structure heterogeneous metal droplet interactive printing molding method, comprising: The geometric model and parameters of the compact phase change heat storage honeycomb structure are designed using topology optimization method; Inputting the geometric model and its parameters into the trajectory planning software to generate a collaborative control code; the collaborative control code includes a first collaborative control code for controlling the collaborative action of the first nozzle and the three-dimensional motion platform, a second collaborative control code for controlling the collaborative action of the second nozzle and the three-dimensional motion platform, and a third collaborative control code for controlling the collaborative action of the first nozzle and the three-dimensional motion platform; Inputting the collaborative control code into the PMAC software built into the PC control machine to generate a printing control program; the printing control program is used by the control machine to control the coordinated actions of the first nozzle, the second nozzle, and the three-dimensional motion platform, wherein the first nozzle contains molten aluminum alloy material, and the second nozzle contains molten phase change material, the alloy material and the phase change material are not mutually soluble below the solidus line, and the three-dimensional motion platform is used to move and carry the printed product; The first nozzle and the second nozzle are heated to a preset temperature respectively, and the heated bed on the three-dimensional motion platform is heated to a preset temperature; In the printing step, the PC controller controls the coordinated action of the first nozzle and the three-dimensional motion platform according to the printing control program to print the honeycomb bottom and honeycomb wall of the honeycomb structure on the hot bed; when the height of the honeycomb wall in the honeycomb structure reaches the set height, forming multiple honeycombs, the second nozzle and the three-dimensional motion platform are switched to coordinate action to fill each honeycomb; when the honeycomb filling is completed, the first nozzle and the three-dimensional motion platform are switched to coordinate action to encapsulate the top of the honeycomb structure filled with phase change material, thus completing the printing of the first layer of honeycomb structure units; The printing steps are cyclically performed to print a set number of honeycomb structure units layer by layer on the first layer of honeycomb structure units until the compact phase change heat storage honeycomb structure is printed.

[0008] A further technical solution of the present invention is that the parameters of the geometric model include the number of layers of the honeycomb structure unit, the number of honeycombs in the honeycomb structure unit, the height of the honeycomb structure unit, the equivalent length of the honeycomb structure unit plane figure and the printing step distance.

[0009] A further technical solution of the present invention is: when heat-conducting pin-fins are designed in the honeycomb, the parameters of the geometric model also include the number of the heat-conducting pin-fins.

[0010] A further technical solution of the present invention is: the preset temperature for heating the first nozzle is 800°C±10°C, the preset temperature for heating the second nozzle is 100°C±5°C, and the preset temperature for heating the hot bed is 400°C.

[0011] A further technical solution of the present invention is: the aluminum alloy material is 6061 aluminum alloy or 6063 aluminum alloy, and the phase change material is tin-bismuth alloy or Wood's alloy.

[0012] A further technical solution of the present invention is that the droplet particle sizes of the first nozzle and the second nozzle are controlled within 100-500 μm.

[0013] A compact phase-change heat storage honeycomb structure printed by the molding method includes multiple layers of honeycomb structural units with the same structure, and the multiple layers of honeycomb structural units are stacked layer by layer from bottom to top to form a compact phase-change heat storage honeycomb structure; wherein the honeycomb structural unit includes a honeycomb structural body, in which a plurality of honeycombs are arranged, each honeycomb is filled with phase change material, and the honeycomb structural body seals and wraps the honeycomb.

[0014] A further technical solution of the present invention is that the honeycomb structure can be designed as a polygon or a column with an irregular cross section.

[0015] A system for interactive printing of heterogeneous metal droplets in a compact phase-change heat storage honeycomb structure, comprising: Trajectory planning software, built into the computer, is used to generate collaborative control code text for the coordinated actions of the first nozzle, the second nozzle, and the three-dimensional motion platform based on the designed geometric model of the compact phase-change heat storage honeycomb structure and its parameters; A PC control machine, a first nozzle, a second nozzle and a three-dimensional motion platform, the PC control machine is electrically connected to the first nozzle, the second nozzle and the three-dimensional motion platform, the PC control machine is used to control the actions of the first nozzle, the second nozzle and the three-dimensional motion platform; the PC control machine has built-in PMAC software, the PMAC software is used to generate a printing control program according to the input collaborative control code text; the PC control machine amplifies its control instructions through an amplifier and then transmits them to the first nozzle and the second nozzle.

[0016] A further technical solution of the present invention is: the three-dimensional motion platform can realize movement in three directions of space, X, Y, and Z. The three-dimensional motion platform is provided with a hot bed, which can be heated to a set temperature; the first nozzle and the second nozzle are both provided with corresponding induction heating furnaces for preheating the nozzles to the set temperature.

[0017] The beneficial effects of the present invention are as follows: a method for interactively printing heterogeneous metal droplets for compact phase-change heat storage honeycomb structures employs an interactive printing method using aluminum alloy materials and phase-change metal dual nozzles. The aluminum alloy material is used to print the honeycomb structure, and the phase-change metal is used to print and fill the honeycombs within the honeycomb structure. The printing of the honeycomb structure first constructs the honeycomb bottom and honeycomb walls, then fills each honeycomb with phase-change metal. Finally, based on the support of the phase-change metal, the top of the honeycomb structure is printed for encapsulation to form a honeycomb structure unit. As needed, the number of honeycomb structure units required for the array can be printed from bottom to top to achieve the printing of a compact phase-change heat storage honeycomb structure. This method, based on the process characteristics of discrete deposition molding using metal droplet printing, controls the coordinated printing of aluminum alloy droplets and phase-change metal droplet dual nozzles by topologically optimizing the honeycomb structure and planning the printing trajectory. When the printed honeycomb structure reaches a certain height, the system automatically switches or simultaneously activates the phase-change metal nozzle to complete the alternating deposition and spatial integration of the two materials. This technology achieves high-precision control of honeycomb wall thickness and layer height in honeycomb structural units, ensuring an optimized balance between heat path continuity, heat storage efficiency and structural stability. The formed phase change heat storage honeycomb structure has the characteristics of compact structure, small volume, uniform filling of phase change material, high heat storage efficiency and good sealing.

[0018] The dual-nozzle interactive printing method achieves high-density integrated printing of aluminum alloy and phase-change metal heterostructures without requiring pre-reserved flow channels, vents, or packaging auxiliary structures. This simplifies the manufacturing process while significantly improving the compactness and overall sealing of the thermal storage structure. This provides technical support for the construction of high-throughput transient thermal storage systems in confined spaces, filling a gap in the fabrication of efficient metal phase-change thermal storage structures for micro-devices.

[0019] Compared with traditional methods, this method has the following advantages: 1. This method utilizes a dual-nozzle interactive printing process to construct a metal phase change composite structure composed of numerous microscale honeycomb cells. Compared to traditional manufacturing methods that require the design of infusion channels and packaging steps, this method eliminates the need for additional phase change material filling channels and brazing sealing structures, significantly simplifying the overall structure. Furthermore, the honeycomb cells are isolated from each other, and the phase change material within each cell is independently sealed, effectively controlling material migration and leakage paths. This significantly reduces the risk of leakage caused by thermal cycling and improves the reliability and service life of the overall thermal control structure.

[0020] 2. This method uses droplet particle size that can be controlled within 100–500 μm, with submillimeter precision printing capability. It can flexibly arrange heterogeneous materials in a limited space, achieving diverse structural configurations and spatial layouts, significantly improving manufacturing complexity and the degree of freedom of heterogeneous structure integration, and providing a fine construction path for compact heat storage structures. While ensuring a high filling rate, it significantly increases the thermal interaction area and the complexity of the heat conduction channel, thereby enhancing the overall heat transfer efficiency.

[0021] 3. During the printing process, since the tin-bismuth alloy is in liquid form below the solidus of the aluminum alloy and forms an interstitial miscible system with the aluminum alloy, and when co-deposited and formed in the same printing layer, the aluminum alloy droplets anchor the tin-bismuth alloy droplets. After the outer wall of the aluminum alloy is constructed, the tin-bismuth alloy droplets can directly and evenly fill the interior of the honeycomb cells in liquid form, realizing dense printing of heterogeneous materials.

[0022] 4. The interactive printing mechanism of aluminum alloy and tin-bismuth alloy breaks through the structural limitations of traditional single-material manufacturing methods, and can achieve high-precision collaborative construction of multiple materials in a single-layer configuration, thereby fundamentally enhancing the design flexibility of the heat conduction path and the overall performance of the thermal management system, providing a new manufacturing method for the preparation of multi-scale, complex topology honeycomb structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 This is a schematic diagram of the aluminum alloy structure printing state in the present invention; Figure 2 This is a schematic diagram of the tin-bismuth alloy printing state in the present invention; Figure 3 The product structure diagrams of each step in the printing steps of Example 1 of the present invention are provided to illustrate the printing process (wherein, a is a cross-sectional view of the designed product, with a regular hexagonal cross-section; b shows the honeycomb structure walls printed to a certain height; c shows the honeycombs filled with printed phase-change metal; d shows the top of the honeycomb structure encapsulated with the support of the phase-change metal, forming the first layer of honeycomb structure units; e shows repeated printing on the first layer of honeycomb structure units, from bottom to top, completing the filling of the honeycomb structure units with the phase-change metal; f shows the top of the fourth layer of honeycomb structure units encapsulated). Figure 4The product structure diagrams of each step in the printing process of Example 2 of the present invention are shown to illustrate the printing process (wherein, a is a cross-sectional view of the designed product, with an irregular polygonal cross-section; b shows the honeycomb structure with the honeycomb walls printed to a certain height and heat-conducting pins and fins printed inside the honeycombs; c shows the honeycombs fully filled with printed phase-change metal; d shows the top of the honeycomb structure encapsulated with the support of the phase-change metal, forming the first layer of honeycomb structure units; e shows repeated printing on the first layer of honeycomb structure units, from bottom to top, completing the phase-change metal filling of the third layer of honeycomb structure units; f shows the top of the honeycomb structure encapsulated with the third layer of honeycomb structure units). In the figure: 1. Three-dimensional motion platform; 2. Hot bed; 3. Honeycomb bottom and honeycomb wall of the honeycomb structure printed by the first nozzle; 4. Aluminum alloy droplets; 5. Molten aluminum alloy; 6. First nozzle; 7. Second nozzle; 8. Molten phase change metal; 9. Phase change metal droplets; 10. Amplifier; 11. PC control machine; 12. Phase change heat storage structure printed interactively by the second nozzle and the first nozzle. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] An embodiment of a compact phase change heat storage honeycomb structure heterogeneous metal droplet interactive printing molding method of the present invention is as follows Figure 1 、 Figure 2 As shown, the method includes: Step 1. Design the geometric model and parameters of the compact phase change heat storage honeycomb structure; determine the geometric model and parameters of the compact honeycomb structure according to the use environment requirements. The parameters of the geometric model include the number of honeycombs in the honeycomb structure unit. n , the height of the honeycomb structure unit H , the equivalent length of the honeycomb unit plane figure L , the number of layers of honeycomb structure unit array ArrayZ , Print pitch DropletStep If the honeycomb is designed with heat-conducting pin fins, the parameters of the geometric model also include the number of heat-conducting pin fins. N .

[0027] The design of the compact honeycomb structure geometric model is achieved using the existing SIMP topology optimization method. This method controls the distribution of materials in the region by material density variables, thereby optimizing the thermal conductivity of the structure. During the topology optimization process, boundary conditions are set: a constant thermal power is applied to the fixed heat source area, and the heat sink area is set as a convection boundary; an upper limit constraint is imposed on the material volume fraction; the initial design space can be set to a hollow or solid area, depending on the specific application requirements. The objective function is to maximize the thermal conductivity efficiency or minimize the thermal resistance as the optimization goal. The temperature field is solved by the finite element method, and the moving asymptote method (MMA) is used for optimization iteration. The final output structure presents a non-uniform pore distribution, has good heat flow channel guidance, and is suitable for additive manufacturing.

[0028] Step 2. Input the geometric model and its parameters into the trajectory planning software to generate a collaborative control code. The collaborative control code includes a first collaborative control code for controlling the collaborative action of the first nozzle and the three-dimensional motion platform, a second collaborative control code for controlling the collaborative action of the second nozzle and the three-dimensional motion platform, and a third collaborative control code for controlling the collaborative action of the first nozzle and the three-dimensional motion platform. The trajectory planning software in this embodiment adopts the trajectory planning software with registration number 2025SR0563612, and the software is famous as "Aluminum Alloy Uniform Micro-droplet Jet 3D Configuration Printing Trajectory Visualization Software" V1.0. This software converts the mathematical model of the lattice structure into a discretized droplet model suitable for micro-droplet 3D printing based on the process characteristics of discrete deposition molding of metal micro-droplet 3D printing, realizes the spatial arraying of the lattice by multiplying the homogeneous three-dimensional coordinates with the transformation matrix, and corrects the intersection position problem in the branch structure. The feature deposition planning method is used for trajectory planning to effectively improve the trajectory accuracy and efficiency, and finally outputs the micro-droplet 3D printing CNC code to achieve high-precision, automatic and rapid generation of the printing trajectory of the complex lightweight lattice sandwich panel structure. The trajectory planning software is built into the computer. By inputting the designed geometric model and its parameters, the CNC code for micro-droplet 3D printing can be output.

[0029] Step 3. Input the collaborative control code into the PMAC software built into the PC controller. PMAC software is an existing print control program. By inputting the print numerical control code into it, a print control program corresponding to the first, second, and third collaborative control codes is generated based on the print numerical control code. The print control program controls the coordinated movement of the first and second nozzles and the three-dimensional motion platform to perform metal droplet 3D printing.

[0030] The present invention adopts two printing nozzles, namely the first nozzle and the second nozzle. The first nozzle is filled with molten aluminum alloy material, and the second nozzle is filled with molten phase change material. The aluminum alloy material is selected from 6061 aluminum alloy or 6063 aluminum alloy, and the phase change material is selected from tin-bismuth alloy or Wood's alloy. The three-dimensional motion platform is used to move and carry printed products. The three-dimensional motion platform can realize movement in three directions of space X, Y, and Z. The three-dimensional motion platform is provided with a hot bed, which can be heated to a set temperature, and the printed product is placed on the hot bed. The first nozzle and the second nozzle are both provided with corresponding induction heating furnaces for preheating the nozzles to a set temperature. The first nozzle, the second nozzle, and the three-dimensional motion platform are all electrically connected to the PC control machine.

[0031] Step 4. First, turn on the induction heating furnace on the two nozzles to preheat the two nozzles, preheat the first nozzle to 800℃±10℃, preheat the second nozzle to 100℃±5℃, and turn on the hot bed heating to preheat the hot bed to 400℃.

[0032] At the beginning of the printing process, the PC controller controls the coordinated action of the first nozzle and the three-dimensional motion platform according to the printing control program, and prints the honeycomb bottom and honeycomb wall of the honeycomb structure with aluminum alloy on the hot bed. If there are heat-conducting pin fins in the structural design, the heat-conducting pin fins will be printed at the same time. When the height of the honeycomb wall in the honeycomb structure reaches the set height, the honeycomb bottom and honeycomb wall will be printed at the same time. H , switching to the second nozzle and the 3D motion platform to work together to print and fill each honeycomb. When the honeycomb filling is complete, that is, the phase change material fills each honeycomb, switching to the first nozzle and the 3D motion platform to work together. Based on the support of the phase change material in the honeycomb, the top of the honeycomb structure is encapsulated with aluminum alloy, enclosing the phase change material in each honeycomb in its own independent space. This completes the printing of the first layer of honeycomb structure units. The droplet size of the first and second nozzles is controlled at 100-500μm, with submillimeter precision printing capability, to achieve diverse structural configurations and layouts in a small space.

[0033] Step 5, looping the printing steps of step 4, completing the printing of the set number of array layers of honeycomb structure units layer by layer on the first layer of honeycomb structure units, until the entire compact phase change heat storage honeycomb structure is printed.

[0034] The above method was used to fabricate a compact phase-change heat storage honeycomb structure. This structure comprises multiple layers of identical honeycomb units stacked layer by layer from bottom to top, forming a compact phase-change heat storage honeycomb structure. The honeycomb units comprise a honeycomb structure body, which contains multiple cells, each filled with phase-change material, and hermetically encapsulates the cells. The honeycomb structure body can be designed as a polygon or a cylinder with an irregular cross-section, depending on the application environment.

[0035] The compact phase-change heat storage honeycomb structure heterogeneous metal droplet interactive printing molding method is achieved through the following system: The system includes trajectory planning software, built into a computer, for generating collaborative control code text based on the designed geometric model of a compact phase-change heat storage honeycomb structure and its parameters. It also includes a PC controller, a first nozzle, a second nozzle, and a three-dimensional motion platform. The PC controller is electrically connected to the first, second, and three-dimensional motion platforms and is used to control the movements of the first, second, and three-dimensional motion platforms. The PC controller also includes built-in PMAC software, which is used to generate a print control program based on the input collaborative control code text. The PC controller amplifies its control instructions through an amplifier and then transmits them to the first and second nozzles.

[0036] Specific application example 1: The above-mentioned heterogeneous metal droplet interactive printing and molding method is used to print a compact aluminum alloy and tin-bismuth alloy heat storage honeycomb structure with a regular hexagonal shape.

[0037] Step 1. Design a specific geometric model structure of a compact metal phase change structure with a regular hexagonal cross section and determine the structural parameters. The maximum outer diameter of the regular hexagon at the bottom of the honeycomb R =4mm, the number of honeycombs in each unit is 72 and the number of unit array layers ArrayZ The internal skeleton structure (i.e., honeycomb structure) is designed based on the level set topology optimization method, using the honeycomb pore heat transfer model as the objective function. The design results are shown in Figure 2. Figure 3 As shown in (a), the porosity of the structure is 95%.

[0038] Step 2. Develop collaborative control code based on the "Trajectory Visualization Software for Uniform Microdroplet Jetting 3D Configuration Printing of Aluminum Alloys," previously developed by our research group. Input the geometric model and its parameters designed in Step 1 into the trajectory planning software to generate the NC code for microdroplet 3D printing. This NC code is then input into the PMAC software built into the PC controller. The PMAC software then generates a NC program for printing, outputting it using the PMAC communication protocol. This program controls the coordinated movement of the first and second nozzles 6 and 7, along with the 3D motion platform 1, for metal microdroplet 3D printing. The trajectory planning method involves layer-by-layer printing, with adjustments made to the print step size and frequency.

[0039] Step 3. Turn on the induction heating furnace of the two nozzles, preset the temperature of the first nozzle 6 to 800℃±10℃, and the temperature of the second nozzle 7 to 100℃±5℃. Turn on the hot bed 2 for heating, and preset the temperature of the hot bed 2 to 400℃. Fill the first nozzle 6 with 6061 aluminum alloy, and the second nozzle 7 with tin-bismuth alloy. The composition of the tin-bismuth alloy is Bi-58% and Sn-42%. After the temperature of the two nozzles and the hot bed 2 stabilizes, test the print step length. DropletStep , adjust to the set step distance of 0.45mm.

[0040] Step 4. Run the printing NC program to make the first nozzle 6 and the three-dimensional motion platform 1 work together to print the droplets on the honeycomb bottom and honeycomb wall. H = 5mm, close the first nozzle 6 (the printing structure is as follows Figure 3 (b)). The 3D motion platform 1 is moved below the second nozzle 7 and reset to its origin. The second nozzle 7 is turned on, and the CNC program is run, causing the second nozzle 7 and the 3D motion platform 1 to coordinately print and fill the honeycomb cavities with the phase change metal (tin-bismuth alloy) until each honeycomb cavity is completely filled with the tin-bismuth alloy.

[0041] Step 5. After the printing and filling is completed, the unit honeycomb structure is encapsulated using the first nozzle 6 with the tin-bismuth alloy in the honeycomb cavity as support to complete the phase change structure printing of a single honeycomb structure unit (i.e., the bottom honeycomb structure unit).

[0042] Step 6. Repeat steps 4 to 5, printing the set 4-layer honeycomb structure unit layer by layer from bottom to top, and finally completing the printing of a compact honeycomb phase change heat storage structure with a regular hexagonal cross-sectional shape.

[0043] Specific application example 2 The above-mentioned heterogeneous metal droplet interactive printing and molding method is used to print a compact aluminum alloy and Wood's alloy heat storage honeycomb structure with an irregular polygonal cross-section.

[0044] Step 1. Design a specific geometric model structure of a compact metal phase change structure with an irregular polygonal cross section and determine the structural parameters. The maximum outer diameter of the honeycomb bottom polygon R =3mm, the wall thickness between two adjacent honeycombs is 0.35mm, the number of honeycombs in each unit is 8, the number of heat conduction pin fins inside the honeycomb is 41, and the number of unit array layers is ArrayZ is 3, the design results are as follows Figure 4 (a) shown.

[0045] Step 2. Develop collaborative control code based on the "Trajectory Visualization Software for Uniform Microdroplet Jetting 3D Configuration Printing of Aluminum Alloys," previously developed by our research group. Input the geometric model and its parameters designed in Step 1 into the trajectory planning software to generate the NC code for microdroplet 3D printing. This NC code is then input into the PMAC software built into the PC controller. The PMAC software generates a NC program for printing, which is then output using the PMAC communication protocol. This program controls the coordinated movement of the first and second nozzles 6 and 7, along with the 3D motion platform 1, for metal microdroplet 3D printing. The trajectory planning method involves layer-by-layer printing, with the PC controlling the positioning of the 3D motion platform 1.

[0046] Step 3. Turn on the induction heating furnace of the two nozzles, preset the temperature of the first nozzle 6 to 850℃±10℃, and preset the temperature of the second nozzle 7 to 100℃±5℃. Turn on the hot bed 2 for heating, and preset the temperature of the hot bed 2 to 450℃. Fill the first nozzle 6 with 6063 aluminum alloy, and the second nozzle 7 with Wood's alloy. The composition of Wood's alloy is Bi-50%, Pb-26.7%, Sn-13.3% and Cd-10.0%. After the temperature of the two nozzles and the hot bed 2 is stable, test the print step distance. DropletStep , adjust to the set step distance of 0.4mm.

[0047] Step 4. Run the printing NC program to make the first nozzle 6 and the three-dimensional motion platform 1 work together to print the droplets on the honeycomb bottom and honeycomb wall, and print the heat-conducting pin fins. When the height of the honeycomb wall reaches the predetermined height, H = 3mm, close the first nozzle 6 (the printing structure is as follows Figure 4 (b)). The 3D motion platform 1 moves below the second nozzle 7 and resets its origin. The second nozzle 7 is turned on, and the CNC program runs, allowing the second nozzle 7 and the 3D motion platform 1 to coordinately print and fill the honeycomb cavities with Wood's metal until each honeycomb cavity is completely filled with Wood's metal. Each honeycomb is equipped with multiple thermally conductive pin fins, which are perpendicular to the bottom wall of the honeycomb structure and have the same height as the honeycomb wall. The pin fins provide structural support and heat conduction.

[0048] Step 5. After the printing and filling is completed, the Wood's alloy in the honeycomb cavity is used as a support to encapsulate the unit honeycomb structure using the first nozzle 6 to complete the phase change structure printing of a single honeycomb structure unit (i.e., the bottom honeycomb structure unit).

[0049] Step 6. Repeat steps 4 to 5, printing the set 4-layer honeycomb structure unit layer by layer from bottom to top, and finally completing the printing of a compact honeycomb phase change heat storage structure with an irregular polygonal cross-sectional shape.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A compact phase change heat storage honeycomb structure heterogeneous metal droplet interactive printing molding method, characterized in that: include: The geometric model and parameters of the compact phase change heat storage honeycomb structure are designed using topology optimization method; Inputting the geometric model and its parameters into the trajectory planning software to generate a collaborative control code, wherein the collaborative control code includes a first collaborative control code for controlling the collaborative action of the first nozzle and the three-dimensional motion platform, a second collaborative control code for controlling the collaborative action of the second nozzle and the three-dimensional motion platform, and a third collaborative control code for controlling the collaborative action of the first nozzle and the three-dimensional motion platform; Inputting the collaborative control code into the PMAC software built into the PC control machine to generate a printing control program; the printing control program is used by the control machine to control the coordinated actions of the first nozzle, the second nozzle, and the three-dimensional motion platform, wherein the first nozzle contains molten aluminum alloy material, and the second nozzle contains molten phase change material, the alloy material and the phase change material are not mutually soluble below the solidus line, and the three-dimensional motion platform is used to move and carry the printed product; The first nozzle and the second nozzle are heated to a preset temperature respectively, and the heated bed on the three-dimensional motion platform is heated to a preset temperature; In the printing step, the PC controller controls the coordinated action of the first nozzle and the three-dimensional motion platform according to the printing control program to print the honeycomb bottom and honeycomb wall of the honeycomb structure on the hot bed; when the height of the honeycomb wall in the honeycomb structure reaches the set height, forming multiple honeycombs, the second nozzle and the three-dimensional motion platform are switched to coordinate action to fill each honeycomb; when the honeycomb filling is completed, the first nozzle and the three-dimensional motion platform are switched to coordinate action to encapsulate the top of the honeycomb structure filled with phase change material, thus completing the printing of the first layer of honeycomb structure units; The printing steps are cyclically performed to print a set number of honeycomb structure units layer by layer on the first layer of honeycomb structure units until the compact phase change heat storage honeycomb structure is printed.

2. The method for interactive printing of heterogeneous metal droplets in a compact phase-change heat storage honeycomb structure according to claim 1 is characterized in that: The parameters of the geometric model include the number of layers of the honeycomb structure unit, the number of honeycombs in the honeycomb structure unit, the height of the honeycomb structure unit, the equivalent length of the honeycomb structure unit plane graph and the printing step distance.

3. The method for interactive printing and forming of heterogeneous metal droplets with a compact phase change heat storage honeycomb structure according to claim 2 is characterized in that: When heat-conducting pin-fins are designed in the honeycomb, the parameters of the geometric model also include the number of heat-conducting pin-fins.

4. The method for interactive printing and forming of heterogeneous metal droplets in a compact phase-change heat storage honeycomb structure according to claim 1 is characterized in that: The preset temperature for the first nozzle heating is 800°C±10°C, the preset temperature for the second nozzle heating is 100°C±5°C, and the preset temperature for the hot bed heating is 400°C.

5. The method for interactive printing and forming of heterogeneous metal droplets with a compact phase-change heat storage honeycomb structure according to claim 1 is characterized in that: The aluminum alloy material is 6061 aluminum alloy or 6063 aluminum alloy, and the phase change material is tin-bismuth alloy or Wood's alloy.

6. The method for interactive printing of heterogeneous metal droplets in a compact phase-change heat storage honeycomb structure according to claim 1 is characterized in that: The droplet size of the first nozzle and the second nozzle is controlled in the range of 100–500 μm.

7. A compact phase change heat storage honeycomb structure printed by the molding method according to any one of claims 1 to 6, characterized in that: The structure includes multiple layers of honeycomb structural units with the same structure, and the multiple layers of honeycomb structural units are stacked layer by layer from bottom to top to form a compact phase change heat storage honeycomb structure; wherein the honeycomb structural unit includes a honeycomb structural body, and a plurality of honeycombs are arranged in the honeycomb structural body, each honeycomb is filled with phase change material, and the honeycomb structural body seals and wraps the honeycomb.

8. The compact phase change heat storage honeycomb structure according to claim 7, characterized in that: The honeycomb structure can be designed as a polygon or a column with an irregular cross section.

9. A system for interactive printing and molding of heterogeneous metal droplets in a compact phase-change heat storage honeycomb structure, the system being applicable to the molding method according to any one of claims 1 to 6, characterized in that: include: Trajectory planning software, built into the computer, is used to generate collaborative control code text for the coordinated actions of the first nozzle, the second nozzle, and the three-dimensional motion platform based on the designed geometric model of the compact phase-change heat storage honeycomb structure and its parameters; A PC control machine, a first nozzle, a second nozzle and a three-dimensional motion platform, the PC control machine is electrically connected to the first nozzle, the second nozzle and the three-dimensional motion platform, the PC control machine is used to control the actions of the first nozzle, the second nozzle and the three-dimensional motion platform; the PC control machine has built-in PMAC software, the PMAC software is used to generate a printing control program according to the input collaborative control code text; the PC control machine amplifies its control instructions through an amplifier and then transmits them to the first nozzle and the second nozzle.

10. The system for interactive printing of heterogeneous metal droplets in a compact phase-change heat storage honeycomb structure according to claim 9, characterized in that: The three-dimensional motion platform can realize movement in three directions of space, X, Y, and Z. The three-dimensional motion platform is provided with a hot bed, which can heat to a set temperature; the first nozzle and the second nozzle are both provided with corresponding induction heating furnaces for preheating the nozzles to the set temperature.

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