A method and device for 3D printing of multilayer structures of functionally gradient materials

Abstract

The present application discloses a method and apparatus for 3D printing a multilayer structure of a functional gradient material, which introduces a step-by-step printing strategy. Unlike the printing of other traditional materials and processes, the single-layer printing process is carried out in steps, corresponding to different printing areas: a border area and a filling area; a top heating module is added to preliminarily pre-cure the liquid material that is easy to flow. The degree of pre-curing is controlled in a semi-cured state. According to the printed functional gradient material, a specific optimized value is selected. The filling area is constrained by the border area, and the material is confined within the border, ensuring the morphology of the entire part. The present application solves the problem of easy spreading during the printing process of thermosetting liquid materials, and realizes the precision, integration, and efficient manufacturing of functional gradient multilayer structures.

Description

Technical Field

[0001] The present application belongs to the technical field of additive manufacturing and functional gradient material manufacturing, and specifically relates to a method and device for 3D printing of a multilayer structure of functional gradient material. Background Art

[0002] Functionally graded materials (FGMs) are advanced heterogeneous composite engineering materials characterized by spatially graded composition, pores, or microstructures. Compared to conventional composite materials, their macroscopic properties exhibit a continuous (or quasi-continuous) gradient in the same direction. This gives them advantages such as excellent insulation, lightweight, corrosion resistance, and ease of processing. Consequently, they are widely used in a wide range of fields, including aerospace, construction, transportation, biomedical engineering, flexible hybrid electronics, national defense, nuclear engineering, and soft robotics, and are attracting increasing attention from scholars and experts both domestically and internationally.

[0003] There are many existing methods for preparing functionally gradient materials (FGMs), including electrodeposition, vapor deposition, plasma spraying, self-propagating high-temperature synthesis (SHS), and powder metallurgy. Although these methods have been widely used to prepare compositionally gradient FGMs, they still have many shortcomings. Electrodeposition can produce FGMs at low temperatures and has low production costs, but it is only suitable for the preparation of thin-film gradient materials. Vapor deposition has a low deposition rate and, in some cases, can form flammable, explosive, or even toxic gases, resulting in significant environmental pollution and high equipment requirements. Plasma spray repair offers high production efficiency and ease of achieving continuous composition changes. It can spray gradient layers onto complex substrates, but its disadvantages include expensive carrier gas, high requirements for spray material quality, and poor interlayer bonding. SHS has limitations in material composition selection, difficulty controlling the reaction process, and poor material performance. Powder metallurgy, while highly reproducible, has complex processes, making it difficult to prepare complex FGMs. Overall, none of these methods can achieve the integrated fabrication of FGMs and three-dimensional structures, and they each suffer from issues such as complex forming processes, high equipment requirements, low efficiency, and high costs.

[0004] Existing 3D printing technologies for manufacturing functionally graded materials include material extrusion processes such as low-temperature deposition, fused deposition, and low-temperature extrusion; powder bed fusion processes such as selective laser melting / sintering and electron beam melting; directed energy deposition technologies such as laser near-net shaping, laser cladding, and laser metal deposition; and stereolithography technologies such as stereolithography and surface exposure rapid prototyping. However, these technologies still have many drawbacks and shortcomings when manufacturing functionally graded materials: powder bed fusion technology is limited in size and prone to the formation of micropores; directed energy deposition materials have a narrow application range and poor surface quality; and stereolithography materials have high loss and demanding working environments. Furthermore, for thermosetting liquid functionally graded materials / structures, the liquid material exhibits severe spreading (flow infiltration) characteristics during the initial printing phase, making precise geometric control difficult. These materials are typically cured using a bottom platform heating method. However, as the number of layers and height of printed parts increase, traditional curing methods using bottom platform heating cannot meet the requirements for timely curing. Therefore, a printing method for thermosetting liquid materials is needed that can achieve precise part shape control while ensuring good interlayer bonding.

[0005] The above information disclosed in this background technology is only used to increase the understanding of the background technology of this application. Therefore, it may contain information that does not constitute the prior art known to ordinary technicians in this field. Summary of the Invention

[0006] In response to some of the problems existing in the prior art, this application provides a method and apparatus for 3D printing of multilayer structures made of functionally gradient materials. This application solves the problem of easy spreading during the printing process of thermosetting liquid materials, achieving precise, integrated, and efficient manufacturing of functionally gradient multilayer structures.

[0007] This application introduces a step-by-step printing strategy. Unlike traditional printing methods using different materials and processes, this strategy divides the single-layer printing process into separate steps, corresponding to different printing zones: the border zone and the fill zone. A top heating module is added to pre-cure the free-flowing liquid material. The pre-cure level is controlled to a semi-cured state, with the optimized value selected based on the functionally gradient material being printed.

[0008] 1) Applying a top heating module improves printing accuracy in the border area and improves curing efficiency in the fill area. When printing high-rise structures, insufficient base heating temperature can cause material flow. Applying top heating ensures the same curing effect when printing high-rise functional gradient structures.

[0009] 2) The border area plays a supporting role. The top heating module quickly pre-cures the border area, bringing it to a semi-cured state and finalizing its shape. The border area effectively improves overall printing accuracy and ensures the desired topography of the entire part. Its auxiliary function enables the formation of complex functionally graded 3D structures.

[0010] 3) The filling area is constrained by the border area, and the material is confined within the border, ensuring the morphology of the entire part.

[0011] In some embodiments of the present application, a 3D printing device for a multilayer structure of a functionally gradient material is provided, wherein the printing device is capable of printing the multilayer structure of the functionally gradient material in steps, dividing the single-layer printing process into steps corresponding to different printing areas: a border area and a fill area; applying top heating to pre-solidify the liquid material;

[0012] The printing device comprises:

[0013] XYZ three-axis motion module, the XYZ three-axis motion module includes an X-axis motion module, a Y-axis motion module, and a Z-axis motion module, wherein the X-axis, Y-axis, and Z-axis are orthogonally installed on the frame in pairs;

[0014] A multi-material and multi-scale printing module for printing functionally gradient materials, mounted on an XYZ three-axis motion module;

[0015] A top heating module, which can be used to pre-curing the liquid material in the border area;

[0016] The multi-material multi-scale printing module is connected to the feeding module and the positive pressure air circuit; the multi-material multi-scale printing module includes multiple supports and multiple printing modules; a printing platform for placing a substrate is provided below the multi-material multi-scale printing module;

[0017] The top heating module includes a bracket V, a fixture I, and a UV curing module. The UV curing module is position-adjusted on the bracket V by the fixture I, and the Z-axis motion module can drive the UV curing module to move up and down.

[0018] In some embodiments of the present application, the multi-material multi-scale printing module includes support I, support II, support III, support IV, printing module I, printing module II, printing module III, and printing module IV.

[0019] In some embodiments of the present application, the feeding module includes barrel I, barrel II, barrel III, and barrel IV, barrel I is used to place printing material I, barrel II is used to place printing material II, barrel III is used to place printing material III, and barrel IV is used to place printing material IV. Printing materials I, II, III, and IV are respectively mixed liquid materials obtained by mixing a first printing raw material and a second printing raw material, and the content of the second printing raw material varies.

[0020] In some embodiments of the present application, each printing module includes a printing nozzle and an adapter. The printing nozzle is mounted on the adapter, and the adapter is connected to the air tube.

[0021] In some embodiments of the present application, a heat insulation device is added to the print head, and the heat insulation device is a hollow design; preferably, the printing platform is installed above the base plate through a bracket VI, the printing platform is equipped with a heating device, and the printing platform can be leveled.

[0022] In some embodiments of the present application, each air pipe air inlet is connected to a solenoid valve, and the solenoid valve is used to control the air inlet switch to achieve air pressure supply.

[0023] In some embodiments of the present application, a method for 3D printing a multilayer structure of a functionally gradient material is further provided, comprising the following steps:

[0024] Step 1: Design the Model

[0025] Design the multilayer structure of functionally gradient materials according to actual needs and obtain a three-dimensional model that meets the requirements;

[0026] Step 2: Model processing and printing preprocessing

[0027] Import the 3D model file into the slicing software to slice it layer by layer, set the model layer information, and export the print model file program.

[0028] The printing substrate is dust-free and placed on the printing platform. The corresponding printing materials are placed on each print head. The working position of each part of the structure and the printing parameters are adjusted accordingly. The printing path program is imported and the printing preparation is completed.

[0029] Step 3: Fabrication of multilayer structures of functionally graded materials

[0030] It includes the following steps:

[0031] Step 3-1: Print the border area

[0032] When printing the base layer, only the printing platform is heated. When printing the gradient layer, the print head and top heating module are activated, the solenoid valve is turned on, and the border area is printed according to the set program. At the same time, top heating is used to complete the printing and pre-curing of the border area.

[0033] Step 3-2: Print the fill area:

[0034] Start the print head and move it to the initial working position according to the designed program running path. Open the solenoid valve to print the fill area within the border area. After printing is completed, the top heating module is used for pre-curing.

[0035] Step 3-3: Switch the print head, adjust the position of the top heating module, and print the mixed solution with different content of the reinforcement phase material in sequence, gradually increasing the number of layers until all functionally gradient layer structures are printed;

[0036] Step 4: Post-printing processing:

[0037] After all printing is completed, turn off the printing module; turn on the top heating module to heat the printed part until it is completely cured; after complete curing, turn off the top heating module and return to the original workstation; turn off the printing platform heating function; remove the printed part from the printing platform.

[0038] In some embodiments of the present application, the printing preprocessing specifically includes:

[0039] (1) Prepare the printing substrate: The printing substrate is a hard float glass sheet. First, wipe the entire float glass sheet with anhydrous ethanol and place it in a vacuum drying oven for heating and drying. Place the glass sheet on the printing platform and fix it;

[0040] (2) Prepare printing materials: Prepare a mixture of different contents for each layer according to the materials required for the printed part;

[0041] (3) Import the printing path program: import the designed printing model file program into the 3D printer;

[0042] (4) Adjust the printing parameters: set the printing pressure, printing speed, and printing platform temperature. If different materials are used to print different functional layers, the parameters will also be different;

[0043] (5) Adjust the XYZ three-axis motion module and solenoid valve to the initial working state.

[0044] In some embodiments of the present application, the process of printing the border area includes the following steps:

[0045] The Z-axis motion module drives the print head and the top heating module down to the designated station. The print head is used to apply positive pressure to the print head, and the printing material is pushed out by the positive pressure to complete the printing of the border area according to the set program path. When printing the base layer, only the printing platform is heated. When printing the gradient layer, the top heating module is turned on and pre-curing is performed along the printing path. After printing is completed, the top heating module is turned off, and the Z-axis motion module drives the print head and the top heating module up to their original position.

[0046] In some embodiments of the present application, the printing fill area process includes the following specific steps:

[0047] The print head moves to the designated station, the air pressure is turned on, and the printing of the filling area is completed according to the set program path; after printing is completed, the top heating module is adjusted so that it and the bottom heating platform are pre-cured together according to the set time; after pre-curing is completed, the top heating module is turned off, and the Z-axis motion module drives the print head and the top heating module to rise to their original position.

[0048] In some embodiments of the present application, the multi-material multi-scale printing module is a multi-nozzle printing module.

[0049] In some embodiments of the present application, the top heating module includes a bracket V, a clamp I, and a UV curing module.

[0050] In some embodiments of the present application, the UV curing module includes a laser, and the position of the laser is adjusted on the bracket V through the clamp I; the Z-axis motion module can drive the laser to move up and down.

[0051] In some embodiments of the present application, due to requirements for different printing accuracies, the number of lasers in the UV curing module may be greater than one.

[0052] In some embodiments of the present application, the feeding module includes a barrel I, a barrel II, a barrel III, and a barrel IV, wherein barrel I is used to place printing material I, barrel II is used to place printing material II, barrel III is used to place printing material III, and barrel IV is used to place printing material IV, and printing materials I, II, III, and IV are respectively mixed liquid materials obtained by mixing a first printing raw material and a second printing raw material with a varying content of the second printing raw material;

[0053] In some embodiments of the present application, the first printing raw material is a thermosetting material, the second printing raw material is an enhanced phase micro-nano material; and the mixed liquid material is a photothermal material.

[0054] In some embodiments of the present application, a heat insulation device is added to the print head. The heat insulation device adopts a hollow design, which greatly reduces heat transfer, ensures smooth material discharge from the print head, and improves printing quality.

[0055] In some embodiments of the present application, the thermal insulation device is a thermal insulation sleeve.

[0056] In some embodiments of the present application, another method for 3D printing a multilayer structure of a functionally gradient material is provided, which specifically includes the following steps:

[0057] Step 1: Printing preprocessing:

[0058] The printing substrate is dust-free and fixed on the printing workbench. The corresponding printing material is placed on the print head. The working position of each component structure and each printing parameter are adjusted accordingly. The printing path program is imported and the printing preparation is completed.

[0059] Step 2: Print the border area:

[0060] When printing the base layer, only the platform is heated. When printing the gradient layer, the print head and top heating module are activated, the solenoid valve is turned on, and the border area is printed according to the set program. At the same time, top heating is used to complete the printing and pre-curing of the border area.

[0061] Step 3: Print the filled area:

[0062] Start the print head and move it to the initial working position according to the designed program running path. Turn on the air pump and solenoid valve to print the fill area within the border area. After printing is completed, the top heating module is used for pre-curing.

[0063] Step 4: Repeat steps 2-3 until all functionally gradient layer structures are printed:

[0064] Switch the print head, adjust the position of the top heating module, and print the mixed liquid with different content of the reinforcement phase material in sequence, gradually increasing the number of layers until all printing is completed.

[0065] Step 5: Post-printing processing:

[0066] Post-printing processing: After all printing is completed, close the printing module; turn on the top heating module to heat the printed part until it is completely cured; after complete curing, turn off the top heating module and return to the original workstation; turn off the printing platform heating function; and remove the printed part from the printing platform.

[0067] In some embodiments of the present application, the printing preparation work in step 1 is specifically as follows:

[0068] (1) Prepare the printing substrate: The printing substrate is a hard float glass sheet. First, wipe the entire float glass sheet (size: 100 mm × 100 mm × 1 mm) with anhydrous ethanol, place it in a vacuum dryer and heat it at 80°C for 5 minutes to make it dust-free. Place the glass sheet on the printing platform and fix it;

[0069] (2) Prepare printing materials: Prepare a mixture of different contents for each layer according to the materials required for the part;

[0070] (3) Prepare the printing program: according to the structure of the manufactured device, make a CAD drawing, use the printing path software to carve out the printing path and convert it into the corresponding G code and import it into the 3D printer;

[0071] (4) Adjust printing parameters: Set printing parameters such as printing pressure, printing speed, and printing platform temperature. If different materials are used to print different functional layers, the parameters will also be different;

[0072] (5) Adjust the XYZ three-axis motion platform, solenoid valve and other parts to the initial working state.

[0073] In some embodiments of the present application, the process of printing the border area in step 2 is specifically as follows:

[0074] The Z-axis motion platform lowers the print head and top heating module to the designated station. The print head then applies positive pressure, pushing the printed material out and completing the printing of the border area according to the programmed path. When printing the base layer, only the platform heats the base layer. When printing the gradient layer, the top heating module is activated, pre-curing the material along the printing path. After printing is complete, the top heating module is turned off, and the Z-axis motion module raises the print head and top heating module to their original position.

[0075] In some embodiments of the present application, the process of printing the filling area in step 3 is as follows:

[0076] The print head moves to the designated station, the air pressure is turned on, and the infill area is printed according to the programmed path. After printing is complete, the top heating module is adjusted so that it and the bottom heating platform perform pre-curing according to the set time. After pre-curing is complete, the top heating module is turned off, and the Z-axis motion module drives the print head and the top heating module to rise to their original position.

[0077] Compared with the prior art, this application has at least the following advantages:

[0078] (1) It can introduce a border area constraint structure to solve the problem of single printing shape, achieve precise control of geometric shapes, and effectively improve printing accuracy and printing stability.

[0079] (2) Applying a top heating module allows for rapid pre-curing of the border area, ensuring the printing accuracy of the part; and improves the curing efficiency of the fill area. In addition, as the number of printing layers increases, the base heating efficiency decreases. Adding an auxiliary heating device allows for rapid heating and curing, achieving precise control of the part shape.

[0080] (3) The single layer is heated to a semi-cured state, which not only achieves precise control of the shape of the part but also provides good interlayer bonding performance.

[0081] (4) Through the step-by-step 3D printing method, precise control of shape and size accuracy can be achieved; the problem of poor performance and accuracy of parts caused by material flow in the existing technology is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] The drawings in the specification, which constitute a part of this application, are used to provide further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute improper limitations on this application.

[0083] Figure 1 Schematic diagram of the overall structure of the 3D printing device of the embodiment of the present application;

[0084] Figure 2 This is a schematic diagram of the structure of a multi-nozzle printing module and its feeding module in an embodiment of the present application;

[0085] Figure 3 This is a schematic diagram of the top heating module structure of an embodiment of the present application;

[0086] Figure 4 Schematic diagram of the print head structure of an embodiment of the present application;

[0087] Figure 5 This is a flow chart of the 3D printing method of the embodiment of the present application;

[0088] Figure 6 It is a schematic diagram of the specific steps of an implementation example of this application.

[0089] Among them, 1. Laser controller, 2. Air pressure pump, 3. Air pipe I, 4. Air pressure gauge, 5. Solenoid valve, 6. Air pipe II, 7. Air pipe III, 8. Air pipe IV, 9. Air pipe V, 10. Z-axis motion module, 11. Connecting frame I, 12. X-axis motion module, 13. Connecting frame II, 14. Y-axis motion module, 15. Y-axis bracket, 16. Multi-nozzle printing module, 1601. Printing module I, 1602. Printing module II, 1603. Bracket I, 1604. Bracket II, 1605. 05. Bracket III, 1606. Dovetail groove I, 1607. Bracket IV, 1608. Print module IV, 160801. Adapter, 160802. Barrel, 160803. Print nozzle, 160804. Thermal insulation sleeve, 1609. Print module III, 17. Print platform, 18. Top heating module, 1801. Fixture I, 1802 Bracket V, 1803. Dovetail groove II, 1804. Laser, 19. Bracket VI, 20. Substrate, 21 Laser power cord. DETAILED DESCRIPTION

[0090] 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.

[0091] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, inside, outside...) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly. In actual applications, due to the limitations of equipment accuracy or installation errors, absolute parallel or vertical effects are difficult to achieve. In the present invention, the description of verticality, parallelism or same direction is not an absolute limiting condition, but means that a vertical or parallel structural setting can be achieved within a preset error range (such as an upper and lower deviation of 5°) and the corresponding preset effect can be achieved. In this way, the technical effect of the limited features can be maximized, and the corresponding technical solution can be easy to implement and has high feasibility.

[0092] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0093] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connect" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. In addition, when describing pipelines, the "connected" and "connected" used in the present invention have the meaning of conducting. When describing electronic components, the "connected" and "connected" used in the present invention have the meaning of conducting through current. The specific meaning needs to be understood in conjunction with the context.

[0094] In embodiments of the present invention, the terms "comprises," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, article, or apparatus comprising a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional identical elements in the process, article, or apparatus comprising the element.

[0095] In the embodiments of the present invention, words such as "exemplarily" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present invention should not be construed as preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0096] The following is combined with Figure 1-6 , further introduce the solution of this application:

[0097] In some embodiments of the present application, a 3D printing device for a multilayer structure of a functionally gradient material is provided, wherein the printing device is capable of printing the multilayer structure of the functionally gradient material in steps, dividing the single-layer printing process into steps corresponding to different printing areas: a border area and a fill area; applying top heating to pre-solidify the liquid material;

[0098] The printing device comprises:

[0099] XYZ three-axis motion module, the XYZ three-axis motion module includes an X-axis motion module 12, a Y-axis motion module 14, and a Z-axis motion module 10, wherein the X-axis, Y-axis, and Z-axis are orthogonally installed on the frame in pairs;

[0100] A multi-material and multi-scale printing module for printing functionally gradient materials, mounted on an XYZ three-axis motion module;

[0101] A top heating module 18, which can be used to pre-curing the liquid material in the border area;

[0102] The multi-material multi-scale printing module is connected to the feeding module and the positive pressure air circuit; the multi-material multi-scale printing module includes multiple brackets and multiple printing nozzles; a printing platform 17 for placing the substrate is provided below the multi-material multi-scale printing module;

[0103] In some embodiments of the present application, the multi-material multi-scale printing module is a multi-nozzle printing module 16, and the multi-nozzle printing module 16 includes multiple supports and multiple printing nozzles.

[0104] The top heating module 18 includes a bracket V1802, a fixture I1801, and a UV curing module. The UV curing module is position-adjusted on the bracket V1802 by the fixture I1801, and the Z-axis motion module 10 can drive the UV curing module to move up and down.

[0105] In some embodiments of the present application, the multi-nozzle printing module includes bracket I 1603, bracket II 1604, bracket III 1605, bracket IV 1607, printing module I 1601, printing module II 1602, printing module III 1609, and printing module IV 1608; each printing nozzle is fixed on the corresponding bracket.

[0106] In some embodiments of the present application, the feeding module includes multiple barrels 160802, preferably including barrel I, barrel II, barrel III, and barrel IV, barrel I is used to place printing material I, barrel II is used to place printing material II, barrel III is used to place printing material III, and barrel IV is used to place printing material IV. Printing materials I, II, III, and IV are respectively mixed liquid materials obtained by mixing a first printing raw material and a second printing raw material, and the content of the second printing raw material varies.

[0107] In some embodiments of the present application, each printing module includes a printing nozzle 160803 and an adapter 160801. The printing nozzle 160803 is installed with the adapter 160801, and the adapter 160801 is connected to the corresponding air tube.

[0108] In some embodiments of the present application, a heat insulation device is added to the print head, and the heat insulation device is a hollow design.

[0109] In some embodiments of the present application, the thermal insulation device is a thermal insulation sleeve 160804.

[0110] In some embodiments of the present application, the printing platform 17 is installed above the base plate through a base, the printing platform 17 is equipped with a heating device, and the printing platform 17 can be leveled.

[0111] In some embodiments of the present application, each air pipe air inlet is connected to the solenoid valve 5, and the solenoid valve 5 is used to control the air inlet switch to achieve air pressure supply.

[0112] The 3D printing device of the embodiment of the present application includes: an XYZ three-axis motion module, a multi-nozzle printing module 16, a top heating module 18, an air pressure supply module, and a frame; the XYZ three-axis motion module includes an X-axis motion module 12, a Y-axis motion module 14, and a Z-axis motion module 10; wherein the three axes are orthogonally installed on the frame.

[0113] In some embodiments of the present application, the Y-axis motion module 14 is a double Y-axis, the X-axis motion module 12 is installed above the double Y-axis through the connecting frame Ⅱ 13, the double Y-axis is installed on the substrate 20 through two Y-axis brackets 15 and is parallel to the substrate 20, and the Z-axis motion module 10 is installed on the X-axis motion module 12 through the connecting frame Ⅰ 11 and is perpendicular to it.

[0114] In some embodiments of the present application, the multi-nozzle printing module 16 can be an ink direct writing printing nozzle, which is used to print functional gradient materials with a variety of different mixing ratios. The multi-nozzle printing module 16 includes a dovetail groove I 1606, a printing nozzle 160803, an insulation sleeve 160804, an adapter 160801 and an air tube. Each printing nozzle is fixed on the dovetail groove I 1606 by a bracket and can be adjusted in position.

[0115] In some embodiments of the present application, the UV curing module includes a laser 1804, and the position of the laser 1804 is adjusted on the bracket V1802 through the clamp I1801; the Z-axis motion module 10 can drive the laser 1804 to move up and down.

[0116] In some embodiments of the present application, the laser 1804 is preferably an ultraviolet laser 1804, and the laser 1804 is fixed on the dovetail groove II 1803 using a clamp, and the position is adjusted by the dovetail structure.

[0117] In some embodiments of the present application, the laser controller 1 is connected to the laser 1804 via a laser power line.

[0118] The air pressure supply module includes an air pressure pump 2, an air pressure gauge 4, an air pipe and an electromagnetic valve 5. The air circuit of each printing module is switched on and off by the electromagnetic valve 5.

[0119] In some embodiments of the present application, specifically, the gas pumped out by the air pressure pump 2 passes through the air pipe I3, and then flows through the air pipe II6, the air pipe III7, the air pipe IV8, and the air pipe V9 into each corresponding nozzle module.

[0120] In some embodiments of the present application, a pressure gauge 4 is provided on the air pipe I3 ​​for monitoring the air pressure during the printing process so as to facilitate regulation according to actual needs.

[0121] In some embodiments of the present application, the solenoid valve 5 is arranged between the air pipe I3 ​​and other branch air pipes for switching control of the air circuit.

[0122] In one embodiment of the present application, a method for 3D printing a multilayer structure of a functionally gradient material includes the following steps:

[0123] Step 1: Design the Model

[0124] First, analyze the structure and function of the parts to be printed, and then design the structure according to the requirements;

[0125] Step 2: Model processing and printing preprocessing

[0126] Model processing includes: importing the model file into the slicing software to slice it layer by layer, setting the model layer information (layer structure, motion path, printing layer thickness), and then exporting the printing model file program.

[0127] Printing preprocessing includes: dust-free treatment of the printing substrate and placing it on the printing platform, placing the corresponding printing material on each printing nozzle, adjusting the working position of each structure and the printing parameters accordingly, importing the printing path program, and preparing for printing; specifically, it can include setting the material ratio (mass fraction or volume fraction), then pre-mixing the materials (ball milling, vacuuming), and setting the functional gradient printing (multi-nozzle 3D printing) parameters (nozzle movement speed, base plate temperature, air pressure, etc.).

[0128] Step 3: Fabrication of multilayer structures of functionally graded materials

[0129] Step 3-1: Print the border area (top auxiliary heating to pre-curing state).

[0130] Step 3-2: Print the filling area, close the air valve after completion, and turn on the top heating device to heat to a semi-cured state.

[0131] Step 3-3: Determine whether printing is complete. If not, replace the print head according to the design requirements (change the relevant printing parameters) and repeat steps 3-1 and 3-2 to print the required number of layers.

[0132] Step 4: Post-printing processing: Post-processing is performed after printing is completed.

[0133] In another embodiment of the present application, Figure 1 The device shown in the figure prints a multilayer structure of a functionally gradient material in an integrated manner, comprising the following steps:

[0134] Step 1: Design the Model

[0135] The multilayer structure of functional gradient materials is designed according to actual needs, and a three-dimensional model that meets the requirements is obtained.

[0136] Step 2: Model processing and printing preprocessing

[0137] (2-1): Model processing. Import the 3D model file into the slicing software and slice it layer by layer. Set the model layer information, including the layer structure, printing motion path, and layer thickness. Finally, export the model file program for printing. Design the functionally graded material multilayer structure to be 4 layers.

[0138] (2-2): Printing material selection. Based on the designed functionally gradient multilayer structure, select and configure the appropriate printing material. In this example, the printing material is polydimethylsiloxane (PDMS), and the reinforcement material is silicon carbide (SiC) with a particle size of 600 nm.

[0139] (2-3): Sample preparation. The mass ratio of PDMS elastomer to curing agent is 10:1. Weigh a certain amount of PDMS elastomer and curing agent, mix them with a glass rod to evenly mix the PDMS elastomer and curing agent, and evacuate for 30 minutes in a -0.07MPa negative pressure vacuum drying oven to remove bubbles, prepare PDMS, and store it in a refrigerator. Weigh a certain amount of SiC particles and PDMS (the content of main agent and curing agent is 10:1) and mix them, then use ultrasound to evenly disperse the SiC particles in the matrix PDMS. Place in a -0.1MPa negative pressure vacuum drying oven for 40 minutes to remove bubbles. Prepare PDMS / SiC mixed solutions with SiC contents of 0wt%, 15wt%, 30wt%, and 45wt%, respectively.

[0140] (2-4): Set initial printing parameters. Set printing parameters such as air pressure, print speed, and build platform temperature. If different materials are used for different functional layers, these parameters will vary. Return the XYZ three-axis motion platform, solenoid valve, and other components to their initial working state. Set the build platform heating temperature to 80°C.

[0141] Step 3: Fabrication of multilayer structures of functionally graded materials

[0142] (3-1): Print the border area. The print head and top heating module descend to the designated station to print the border area. When printing the base layer, only the platform is heated. When printing the gradient layer, the top heating module is turned on and pre-cured along the printing path. After printing is complete, the top heating module is turned off, and the print head and top heating module rise to their original position.

[0143] (3-2): Print the fill area. The print head prints the fill area. After printing is complete, the top heating module is adjusted to pre-curing the part together with the bottom heating platform according to the set time. After pre-curing is complete, the top heating module is turned off and the print head returns to its original position.

[0144] (3-3) Switch the print head, adjust the position of the top heating module, and print PDMS / SiC composite materials with different SiC contents in sequence, gradually increasing the number of layers, and repeat steps (3-1)-(3-2) until all printing is completed.

[0145] Step 4: Post-processing.

[0146] After all printing is completed, turn off the printing module; turn on the top heating module to heat the printed part until it is completely cured; after complete curing, turn off the top heating module and return to the original workstation; turn off the printing platform heating function; remove the printed part from the printing platform.

[0147] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for 3D printing a multilayer structure of a functionally gradient material, characterized in that: The following steps are involved: Step 1: Design the model: Design the multilayer structure of the functionally gradient material according to actual needs and obtain a three-dimensional model that meets the requirements; Step 2: Model processing and printing preprocessing: Import the 3D model file into the slicing software for slicing layer by layer, set the model layer information, and export the printing model file program; The printing substrate is dust-free and placed on the printing platform. The corresponding printing materials are placed on each print head. The working position of each part of the structure and the printing parameters are adjusted accordingly. The printing path program is imported and the printing preparation is completed. Step 3: Fabrication of a multilayer structure of functionally gradient materials, which includes the following steps: Step 3-1: Printing the border area: When printing the base layer, only the printing platform is heated; when printing the gradient layer, the print head and the top heating module are activated, the solenoid valve is turned on, and the border area is printed according to the set program, supplemented by top heating, to complete the printing and pre-curing of the border area; Step 3-2: Print the fill area: Start the print head and move it to the initial working position according to the designed program running path. Open the solenoid valve to print the fill area within the border area. After printing is completed, the top heating module is used for pre-curing. Step 3-3: Switch the print head, adjust the position of the top heating module, and print the mixed solution with different content of the reinforcement phase material in sequence, gradually increasing the number of layers until all functionally gradient layer structures are printed; Step 4: Post-printing processing: After all printing is completed, turn off the printing module; turn on the top heating module to heat the printed part until it is completely cured; after it is completely cured, turn off the top heating module and return to the original position; turn off the printing platform heating function; remove the printed part from the printing platform; The process of printing the border area includes the following steps: The Z-axis motion module drives the print head and the top heating module down to the designated position. The print head is used to apply positive pressure to the print head, which pushes the printing material out and completes the printing of the border area according to the set program path. When printing the base layer, heating is only performed through the printing platform; when printing the gradient layer, the top heating module is turned on and pre-curing is performed along the printing path; after printing is completed, the top heating module is turned off, and the Z-axis motion module drives the print head and the top heating module to rise to their original position.

2. A 3D printing method for a functionally gradient material multilayer structure according to claim 1, characterized in that: The following steps are involved: The printing preprocessing specifically includes: (1) Prepare the printing substrate: The printing substrate is a hard float glass sheet. First, wipe the entire float glass sheet with anhydrous ethanol and place it in a vacuum drying oven for heating and drying. Place the glass sheet on the printing platform and fix it; (2) Prepare printing materials: Prepare a mixture of different contents for each layer according to the materials required for the printed part; (3) Import the printing path program: import the designed printing model file program into the 3D printer; (4) Adjust the printing parameters: set the printing pressure, printing speed, and printing platform temperature. If different materials are used to print different functional layers, the parameters will also be different; (5) Adjust the XYZ three-axis motion module and solenoid valve to the initial working state.

3. The method for 3D printing a multilayer structure of a functionally gradient material according to claim 1, characterized in that: The printing filling area process includes the following specific steps: The print head moves to the designated station, the air pressure is turned on, and the printing of the filling area is completed according to the set program path; after printing is completed, the top heating module is adjusted so that it and the bottom heating platform are pre-cured together according to the set time; after pre-curing is completed, the top heating module is turned off, and the Z-axis motion module drives the print head and the top heating module to rise to their original position.

4. A method for 3D printing a multilayer structure of a functionally gradient material according to any one of claims 1 to 3, characterized in that: The printing method uses a functional gradient material multilayer structure 3D printing device for printing. The printing device can print the functional gradient material multilayer structure in steps, and the single layer printing process is divided into steps, corresponding to different printing areas: a frame area and a filling area; Apply top heating to pre-cure the liquid material; The printing device comprises: XYZ three-axis motion module, the XYZ three-axis motion module includes an X-axis motion module, a Y-axis motion module, and a Z-axis motion module, wherein the X-axis, Y-axis, and Z-axis are orthogonally installed on the frame in pairs; A multi-material and multi-scale printing module for printing functionally gradient materials, mounted on an XYZ three-axis motion module; A top heating module, which can be used to pre-curing the liquid material in the border area; The multi-material multi-scale printing module is connected to the feeding module and the positive pressure air circuit; the multi-material multi-scale printing module includes multiple supports and multiple printing modules; a printing platform for placing a substrate is provided below the multi-material multi-scale printing module; The top heating module includes a bracket V, a fixture I, and a UV curing module. The UV curing module is adjusted on the bracket V by the fixture I, and the Z-axis motion module can drive the UV curing module to move up and down; The feeding module includes a barrel I, a barrel II, a barrel III, and a barrel IV. Barrel I is used to place printing material I, barrel II is used to place printing material II, barrel III is used to place printing material III, and barrel IV is used to place printing material IV. Printing materials I, II, III, and IV are respectively mixed liquid materials of a first printing raw material and a second printing raw material with a varying content of the second printing raw material. A heat insulation device is added to the printing module, and the heat insulation device is a hollow design.

5. The method for 3D printing a multilayer structure of a functionally gradient material according to claim 4, characterized in that: The multi-material and multi-scale printing module includes a bracket I, a bracket II, a bracket III, a bracket IV, a printing module I, a printing module II, a printing module III, and a printing module IV.

6. The method for 3D printing a multilayer structure of a functionally gradient material according to claim 4, characterized in that: Each printing module includes a printing nozzle and an adapter. The printing nozzle is mounted on the adapter, and the adapter is connected to the air pipe.

7. The method for 3D printing a multilayer structure of a functionally gradient material according to claim 4, characterized in that: The printing platform is installed above the bottom plate through a base. The printing platform is equipped with a heating device and can be leveled.

8. The method for 3D printing a multilayer structure of a functionally gradient material according to claim 6, characterized in that: The air inlet of each air pipe is connected to the solenoid valve, and the air inlet switch is controlled by the solenoid valve to realize the supply of air pressure.

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