WO2022151539A1 - 功能梯度材料和三维结构一体化制造的3d打印设备及方法 - Google Patents

功能梯度材料和三维结构一体化制造的3d打印设备及方法 Download PDF

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WO2022151539A1
WO2022151539A1 PCT/CN2021/074879 CN2021074879W WO2022151539A1 WO 2022151539 A1 WO2022151539 A1 WO 2022151539A1 CN 2021074879 W CN2021074879 W CN 2021074879W WO 2022151539 A1 WO2022151539 A1 WO 2022151539A1
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printing
module
mixing
sacrificial layer
nozzle
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PCT/CN2021/074879
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English (en)
French (fr)
Inventor
兰红波
郭鹏飞
林鑫
张广明
朱晓阳
赵佳伟
许权
杨建军
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青岛理工大学
青岛五维智造科技有限公司
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Priority to US17/636,577 priority Critical patent/US12083745B2/en
Publication of WO2022151539A1 publication Critical patent/WO2022151539A1/zh

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
    • B29C64/10—Processes of additive manufacturing
    • B29C64/106—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material
    • B29C64/124—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material using layers of liquid which are selectively solidified
    • B29C64/129—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material using layers of liquid which are selectively solidified characterised by the energy source therefor, e.g. by global irradiation combined with a mask
    • B29C64/135—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material using layers of liquid which are selectively solidified characterised by the energy source therefor, e.g. by global irradiation combined with a mask the energy source being concentrated, e.g. scanning lasers or focused light sources
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
    • B29C64/10—Processes of additive manufacturing
    • B29C64/106—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B7/00—Mixing; Kneading
    • B29B7/02—Mixing; Kneading non-continuous, with mechanical mixing or kneading devices, i.e. batch type
    • B29B7/06—Mixing; Kneading non-continuous, with mechanical mixing or kneading devices, i.e. batch type with movable mixing or kneading devices
    • B29B7/10—Mixing; Kneading non-continuous, with mechanical mixing or kneading devices, i.e. batch type with movable mixing or kneading devices rotary
    • B29B7/12—Mixing; Kneading non-continuous, with mechanical mixing or kneading devices, i.e. batch type with movable mixing or kneading devices rotary with single shaft
    • B29B7/14—Mixing; Kneading non-continuous, with mechanical mixing or kneading devices, i.e. batch type with movable mixing or kneading devices rotary with single shaft with screw or helix
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
    • B29C64/10—Processes of additive manufacturing
    • B29C64/106—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material
    • B29C64/118—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material using filamentary material being melted, e.g. fused deposition modelling [FDM]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
    • B29C64/20—Apparatus for additive manufacturing; Details thereof or accessories therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
    • B29C64/20—Apparatus for additive manufacturing; Details thereof or accessories therefor
    • B29C64/205—Means for applying layers
    • B29C64/209—Heads; Nozzles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
    • B29C64/30—Auxiliary operations or equipment
    • B29C64/307—Handling of material to be used in additive manufacturing
    • B29C64/314—Preparation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
    • B29C64/30—Auxiliary operations or equipment
    • B29C64/307—Handling of material to be used in additive manufacturing
    • B29C64/321—Feeding
    • B29C64/336—Feeding of two or more materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
    • B29C64/40—Structures for supporting 3D objects during manufacture and intended to be sacrificed after completion thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y10/00—Processes of additive manufacturing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y30/00—Apparatus for additive manufacturing; Details thereof or accessories therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y40/00—Auxiliary operations or equipment, e.g. for material handling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y40/00—Auxiliary operations or equipment, e.g. for material handling
    • B33Y40/10—Pre-treatment
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

Definitions

  • the present invention relates to the technical field of additive manufacturing and functionally graded material/structure manufacturing, in particular to a 3D printing device and method for the integrated manufacture of functionally graded materials and three-dimensional structures.
  • Functionally graded material refers to the use of advanced composite technology in the preparation process of the material, so that the microscopic elements (including material components and microstructure) of the material are continuous in a specific direction (or It is a kind of heterogeneous composite material in which the macroscopic properties of the material also show a continuous (or quasi-continuous) gradient change in the same direction.
  • the distinctive feature of functionally graded materials is to add an intermediate transition layer with a gradient of material content in traditional composite materials, so that the physical properties of the material are in a gradual form, avoiding or alleviating the traditional composite materials due to too much difference in physical properties. Defects such as stress concentration, cracking and spalling during use.
  • functionally graded materials also have very good designability. By changing the volume content of each component material or the spatial distribution of the microstructure in a targeted manner, it can optimize the internal stress distribution of the structure and meet the performance requirements of different parts of the material. . As a new advanced material, it not only solves the interfacial stress problem of composite materials, but also maintains the composite properties of materials, as well as the tailoring characteristics and versatility of performance. Due to their excellent physical and chemical properties, functionally graded materials have been used in aerospace, biomedical, nuclear engineering, energy, electromagnetics, optics, flexible electronics, wearable devices, soft robots, high voltage and many other fields and industries. Broad engineering application prospects.
  • functionally graded materials are divided into: (1) inorganic functionally graded materials, mainly including metal/ceramic, metal/non-metal, metal/metal and ceramic/non-metal, etc.; (2) polymerization functionally graded materials, mainly including polymers/polymers, polymers/ceramics, polymers/metals, and polymers/inorganic fillers, etc., but the current research and development of polymer functionally graded materials is mainly focused on There are two categories of polymers/polymers and polymers/inorganic fillers.
  • PGM Polymer functionally graded materials mainly refer to a general term for a class of functionally graded materials whose matrix materials are polymer materials. Compared with inorganic functionally graded materials, polymer functionally graded materials have more extensive engineering applications.
  • the existing main preparation methods of functionally graded materials chemical vapor deposition method, physical evaporation method, plasma spraying method, self-propagating high temperature synthesis method, powder metallurgy method, centrifugal forming method, grouting method, chemical vapor deposition method Penetration method and electrolytic extraction method, etc.
  • the above-mentioned traditional preparation methods can only be used to manufacture quasi-continuous (layered gradients, and the preparation of continuous functionally graded materials cannot be realized) functionally graded materials, which are formed of functionally graded materials and parts with relatively simple structures, and it is difficult to achieve more than two types of materials.
  • low-viscosity matrix materials no filler added or low filler content
  • the solid phase content of the added second material is high or the second material with a larger particle size is added, there is severe material sedimentation, stable printing cannot be achieved, and it is difficult to ensure continuous gradient performance.
  • the accuracy of printing functionally graded parts is poor.
  • the existing 3D printing technology for manufacturing functionally graded materials/structural parts cannot yet realize the manufacture of functionally graded materials/structural parts with micro-scale and sub-micro-scale precision.
  • the minimum amount of printing material (droplets, filaments) from extrusion/jetting is still relatively large, especially for the layer thickness that cannot be precisely controlled (the composition of filler or the second material does not change continuously, and the process parameters vary. Real-time adjustment cannot be ensured, and curing control consistency is poor).
  • the functionally graded materials/structural parts prepared by various 3D printing technologies have poor interlayer bonding strength and continuous gradient performance. Due to the constant changes in the components of the printing materials, it is difficult to achieve accurate and rapid curing (especially UV light).
  • the composition of the material is constantly changing, which brings great challenges to printing.
  • the parameters optimized for the existing 3D printing process are all for specific materials, even if it is a composite material, the composition/component of the material will not change during the printing process.
  • the composition/composition of the material is constantly changing, especially the process parameters of curing and the parameters affecting properties such as rheology are constantly changing, which will lead to the printed structure even using optimized process parameters. Small changes occur, resulting in constant changes in performance and geometry and surface quality, which create serious challenges for print consistency.
  • the existing technology (especially for photosensitive resin-based materials) is not fully cured, and the material thickness of each layer varies unevenly (due to the uncertainty of the degree of spread of the printed liquid photosensitive material), resulting in the thickness of each layer and the internal and external geometry. Changes occur, and the consistency of each print is poor and cannot meet actual production requirements. (6) The mixing of each component material is uneven. None of these existing technologies provide a dedicated mixing unit, resulting in uneven mixing, which makes it impossible to prepare truly high-performance functionally graded materials/structural parts.
  • the materials currently suitable for LENS and laser cladding processes are basically powder and wire, and the shapes and geometric dimensions of powder and wire are also strictly limited; the currently suitable material for FDM is wire, and its geometric There are also stricter limits on size; polymer jetting is currently only suitable for very low-viscosity photosensitive resin materials; powder bed fusion is suitable for powdery materials, which have more stringent restrictions on geometry and size. (11) Each manufacturing technology also has strict restrictions on suitable forming materials. LENS, laser cladding and powder bed fusion technology are mainly used for metal-based functionally graded materials/structure manufacturing, and FDM is mainly used for thermoplastic-based functionally graded materials. / structure manufacturing, Polyjet is mainly used for photocurable resin-based functionally graded materials / structure manufacturing.
  • An invention patent previously disclosed by the inventor discloses a 3D printer and working method for the integrated manufacturing of functionally graded materials and molding structures.
  • the method is mainly applicable to the manufacture of functionally graded parts with relatively simple geometric shapes, that is, the raw materials are all solid (solid), that is, powder/granular solid and powder/granular solid mixed printing realizes the integrated manufacture of functionally graded materials and molding structures.
  • the methods of manufacturing functionally graded materials/structures based on 3D printing are divided into three categories: (1) The raw materials are all liquid (liquid), that is, different volume fractions (or mass fractions) of liquid-liquid mixed 3D Printing; (2) One raw material is liquid (liquid state), and the other is solid (powder or granular solid, and can be uniformly mixed in the first liquid raw material), that is, liquids with different volume fractions (or mass fractions) Solid hybrid 3D printing; (3) The raw materials are all solid (solid, powder, granular, wire, etc.), that is, solid-solid hybrid 3D printing with different volume fractions (or mass fractions).
  • This invention patent cannot realize the printing of functionally graded materials/structural parts of the previous two material systems.
  • due to the very long distance from the raw material feed end to the printing nozzle there are a lot of materials stored in the entire pipeline, and the hysteresis of printing is very serious, especially if it is impossible to realize small-sized functionally graded materials/structural parts, it is also difficult to achieve complex Fabrication of 3D geometric structures.
  • This invention patent is completely unable to realize the integrated manufacturing of the first two types of material systems, energy gradient materials and molding structures.
  • Another invention patent previously disclosed by the inventor application number: 2020101020099, 3D printing device and printing method for integrated manufacturing of functionally graded materials and structures
  • the main purpose of the invention is to realize the realization of liquid (matrix) and powdered solid (enhanced It can effectively remove the bubbles generated during the mixing process of the liquid and the powdery solid, so as to ensure the quality of the 3D printed product.
  • the problem aimed at is that in the process of mixing liquid and solid powder, there are usually the following problems: (1) During the mixing process, the powder is easy to agglomerate and difficult to disperse, which is a common problem in the existing solid-liquid mixing; (2) If the liquid is mixed If the viscosity is too high, air will be brought in during the mixing process, bubbles will easily appear, and it is difficult for the solid powder to be mixed evenly in the liquid; (3) The solid-liquid mixed materials of different proportions can realize feeding, mixing and extrusion during the printing process. The whole process takes a short time and requires a fast response speed.
  • the control valve After maintaining for a certain period of time, the control valve is opened to restore normal pressure, and then a certain positive pressure is applied, and the high-voltage power supply is turned on.
  • the three-dimensional moving bracket follows the programmed X and Y trajectories. It is necessary to pump negative pressure to the mixing chamber to remove air bubbles in the mixed material. At this time, the printing process will stop, and the integration of continuous functional gradient materials and complex three-dimensional structures cannot be realized. manufacture.
  • the raw materials are liquid and powdered solid mixed printing to realize the integrated manufacturing of continuous functionally graded materials and molding structures.
  • the solid fillers of high solid content materials have serious sedimentation, especially When the particle size is relatively large, there will be problems such as uneven mixing and low mixing efficiency.
  • powders are easy to agglomerate, especially nanomaterials, which are difficult to disperse uniformly.
  • the purpose of the present invention is to provide a 3D printing device and method for the integrated manufacture of functionally graded materials and three-dimensional structures, which is suitable for the integrated manufacture of polymer-based continuous functionally graded materials and complex three-dimensional structures, especially It can realize the integrated manufacturing of continuous functionally graded materials with high solid content and high viscosity and complex three-dimensional structures, which solves the problem of printing large-sized parts, due to long printing time or materials with high solid content and materials containing micro-scale fillers.
  • embodiments of the present invention provide a 3D printing device for integrated manufacturing of functionally graded materials and three-dimensional structures, including an active hybrid module, a passive hybrid printing module, and a constrained sacrificial layer printing module, and the input of the active hybrid module The end is connected with multiple anti-settling feeding modules to realize active mixing of various materials; the output end of the active mixing module is connected to the passive mixing printing module, which is used to connect the actively mixed materials to the passive mixing printing module for static mixing ;
  • the passive hybrid printing module and the constraining sacrificial layer printing module are installed on one side of the XYZ three-axis module; the constraining sacrificial layer printing module is connected to the constraining sacrificial layer feeding module, and can print to form complex shapes with the assistance of the constraining sacrificial layer material.
  • Functional gradient three-dimensional structure
  • the active mixing module includes a vibrating mixing chamber and an active stirring screw installed in the vibrating mixing chamber.
  • the vibrating mixing chamber can perform ultrasonic vibration; the various materials entering the active mixing module are uniformly stirred under the action of ultrasonic vibration and active stirring screw. Mixed and extruded by active stirring screw;
  • the passive hybrid printing module includes a passive hybrid printing nozzle and a cylinder module I that can drive the passive hybrid printing nozzle to move up and down;
  • the constrained sacrificial layer printing module includes a constrained sacrificial layer printing nozzle and a cylinder module II that can drive the constrained sacrificial layer printing nozzle to move up and down. .
  • the embodiment of the present invention also provides a 3D printing device for the integrated manufacture of functionally graded materials and three-dimensional structures, including an active mixing module, a passive mixing printing module, and an FDM printing module, wherein the input end of the active mixing module is connected to the A plurality of anti-settling feeding modules are connected to realize active mixing of various materials; the output end of the active mixing module is connected to the passive mixing printing module for connecting the actively mixed materials to the passive mixing printing module for static mixing;
  • the passive hybrid printing module and the FDM printing module are installed on one side of the XYZ three-axis module; the FDM printing module is connected to the FDM wire feeding module, and the FDM wire feeding module can transport the wire into the FDM printing module;
  • the active mixing module includes a vibrating mixing chamber and an active stirring screw installed in the vibrating mixing chamber.
  • the vibrating mixing chamber can perform ultrasonic vibration; the various materials entering the active mixing module are uniformly stirred under the action of ultrasonic vibration and active stirring screw. Mixed and extruded by active stirring screw;
  • the passive hybrid printing module includes a passive hybrid printing nozzle and a cylinder module I that can drive the passive hybrid printing nozzle to move up and down;
  • the FDM printing module includes an FDM printing nozzle and a cylinder module IV that can drive the FDM printing nozzle to move up and down.
  • the active stirring screw is connected to a stepping motor, and the active stirring screw is axially installed along the interior of the vibrating mixing chamber; one end of the vibrating mixing chamber is provided with a discharge port, and the discharge port is connected to the passive mixing printing nozzle. Connected; the side of the vibrating mixing chamber is provided with a plurality of feeding ports for connecting the anti-settling feeding module.
  • the side of the vibrating mixing chamber is provided with a feeding port I and a feeding port II, the feeding port I is connected with the anti-settling feeding module I, and the feeding port II is connected with the anti-settling feeding module II ;
  • the anti-settling feeding module I is used to place the printing material I, and the printing material I is the first printing raw material, and the first printing raw material is a light-curing or heat-curing material; the anti-settling feeding module II is used to place the printing material II, and the printing material II It is a uniform mixing liquid of the first printing raw material and the second printing raw material; the second printing raw material adopts micro-nano material.
  • the passive mixing printing nozzle includes a static mixer and a passive mixing printing nozzle.
  • the passive mixing printing nozzle is installed at one end of the static mixer, and the other end of the static mixer is connected to the passive mixing feed port and the passive mixing positive pressure. air port;
  • the passive mixing feed port is connected to the active mixing module through a hose, and the passive mixing positive pressure air port is connected to the positive pressure air circuit through a hose; the passive mixing printing nozzle is connected to the positive electrode of the high-voltage DC power supply.
  • the constraining sacrificial layer printing nozzle includes a constraining sacrificial layer storage bucket, one end of the constraining sacrificial layer storage bucket is installed with a heating block for the constraining sacrificial layer nozzle and a constraining sacrificial layer printing nozzle, and the other end of the constraining sacrificial layer storage bucket is installed
  • An adapter is installed, and the constraining sacrificial layer storage barrel is connected with the constraining sacrificial layer feed port and the constraining sacrificial layer positive pressure air port through the adapter; the constraining sacrificial layer printing nozzle is connected to the positive pole of the high-voltage direct current power supply.
  • the UV curing module includes a UV curing unit and a cylinder module III that can drive the UV curing unit to move up and down.
  • a printing platform for placing the substrate is arranged below the passive hybrid printing nozzle, the printing platform is installed above the bottom plate through a base, a heating device is installed on the printing platform, and the printing platform can be leveled.
  • the embodiments of the present invention also provide a 3D printing method for the integrated manufacture of functionally graded materials and three-dimensional structures, using the 3D printing equipment, including:
  • Step 1 Print Processing:
  • Print material II mix the first printing material and the second printing material uniformly according to the design requirements; place printing material I in anti-settling feeding module I, printing material II in anti-settling feeding module II, and place printing material III in anti-settling feeding module II To the constraining sacrificial layer feeding module or FDM wire feeding module;
  • Step 2 Print the Constraint Sacrificial Layer:
  • Cylinder module II or cylinder module IV drives the constraining sacrificial layer printing nozzle or FDM printing nozzle to descend to the printing station IIB, activate the constraining sacrificial layer feeding module or FDM wire feeding module, and use the constraining sacrificial layer printing nozzle or FDM printing nozzle according to Set the path to complete the printing of the constraint layer and support structure;
  • Step 3 Print the functional gradient layer:
  • the passive hybrid printing nozzle moves to the printing station IA, and the cylinder module II drives the passive hybrid printing nozzle to descend to the printing station IB; according to the set gradient ratio, the anti-settling feeding module I and the anti-settling feeding module II move to the active mixing respectively.
  • the vibrating mixing chamber in the module feeds the material, which is stirred and vibrated by the active stirring screw in the active mixing and further uniformly mixed by the static mixer; under the control of the extrusion force of the positive pressure control unit, the functionally graded material is extruded. Go to the discharge port of the printing nozzle, and complete the printing of the functional gradient layer according to the set path; the printed functional gradient layer material is in the constraining sacrificial layer;
  • the UV curing unit moves to the printing station IIIA, and the cylinder module III drives the UV curing unit to descend to the printing station IIIB; according to the set time, the printed functional gradient layer is pre-cured and formed by UV light curing or heat curing; After the gradient layer is pre-cured and formed, the cylinder module III drives the UV curing unit to rise to the initial printing station III C;
  • Step 5 Repeat the operations of steps 2-4 until the printing of all functional gradient layer structures is completed;
  • Step 6 Post-Print Processing:
  • the anti-settling feeding module I After all functional gradient layers are printed, turn off the anti-settling feeding module I, anti-settling feeding module II, constrained sacrificial layer feeding module or FDM wire feeding module; active mixing module, passive hybrid printing nozzle, constrained sacrificial layer printing nozzle or The FDM printing nozzle and UV curing unit return to the initial position; the heating function of the printing platform is turned off; the positive pressure air circuit and the high-voltage DC power supply are turned off;
  • the printed functionally graded part is removed from the printing platform and placed in a UV curing oven or a vacuum oven for post-curing; the constraining sacrificial layer is removed to obtain a finished functionally graded part.
  • step 2 if the printed constraining layer and support structure are microscale, the material jet printing mode is adopted; if the printed structure is mesoscopic and macroscale, the material extrusion printing mode is adopted.
  • the material jet printing mode is adopted; if the printed structure is mesoscopic and macro-scale, the material extrusion printing mode is adopted.
  • lift-off and removal methods are used depending on the chosen confinement sacrificial layer material. If it is a water-soluble material, first perform manual peeling, and then place it in hot water at 40-70 ° C to remove it completely. If it is a special material such as HIPS, limonene solution is mainly used for dissolution and removal. If it is ABS, PLA and other materials, it is mainly removed by manual peeling, and other processing methods such as ultrasound can be assisted, but the principle of not destroying the functionally graded parts is followed.
  • the printed functionally graded layer is pre-cured, and the degree of pre-curing is controlled within the range of 60-90% of the fully cured, and specific optimized values are selected according to the printed functionally graded material.
  • One or more embodiments of the present invention adopt the method of uniform mixing of three-stage materials to solve the problems of material agglomeration and uneven mixing, and realize efficient mixing of two or more materials, and printing of continuous gradient materials.
  • the first level of mixing is to fully premix the printing material II (the composite material after the first printing raw material and the second printing raw material are uniformly mixed), and use surface modification (to avoid agglomeration, especially nanoscale fillers and high solid content) Filler, there is a serious agglomeration phenomenon), ultrasonic vibration or ball milling and other processes to achieve full and even mixing of the filler and the liquid matrix material.
  • the second-stage mixing, the second-stage mixing of the materials is realized by screw mixing, so that the printing material I and the printing material II are continuously and stably mixed uniformly in the vibrating mixing chamber.
  • the third-stage mixing, the third-stage mixing of the materials is realized by means of vibration. Finally, it is sent to the passive mixing nozzle to achieve continuous and stable printing. In this way, after the multi-stage mixing of the material, it is ensured that the printing material reaching the nozzle has a better continuous functional gradient performance.
  • One or more embodiments of the present invention solve the problem of functional gradient manufacturing of high-solid content, high-viscosity materials by introducing active mixing (screw extrusion + ultrasonic vibration); at the same time, active mixing can effectively prevent materials from being in the printing process.
  • the problem of sedimentation occurs in the production process; fully utilizes and combines the advantages of the active mixing module and the passive mixing printing nozzle to realize the integrated manufacturing of continuous functional gradient materials and complex three-dimensional structures of raw materials with high solid content and high viscosity; by setting the anti-settling supply Material module I, anti-settling feeding module II, etc., solve the problem that printing materials, especially those containing micro-scale fillers and high-solid content fillers, are prone to sedimentation, resulting in inability to print stably, especially for large-sized parts, due to the long printing time. This results in serious material settling, making it impossible to print stably; using the inverted active mixing module and other strategies to solve the problem of mixed bubble removal in multi-material printing, and improve the performance and accuracy of printing functionally graded parts.
  • One or more embodiments of the present invention introduce a constrained sacrificial layer structure.
  • the composition and properties of the material remain basically unchanged during the printing process, and the optimized printing process parameters are usually applicable throughout the printing process.
  • the introduction of a constrained sacrificial layer structure is proposed. Its advantages and significant effects:
  • the optimized process window is applicable in a very wide range.
  • Using the constrained sacrificial layer structure can ensure that the thickness of each layer of the printed functionally graded material/structure is the set thickness, regardless of whether it is in the low-content filler functionally graded region or the high-content filler functionally graded region for a single functionally graded part printed , using the constrained sacrificial layer structure can ensure the same thickness (or set variable thickness, or adaptive thickness), especially for the same print in different areas, the same batch, and different batches, the printed energy gradient The parts have good consistency.
  • One or more embodiments of the present invention introduce a two-step curing strategy, and with the assistance of constraining the sacrificial layer structure, the printing efficiency can be effectively improved, and the interlayer bonding strength and continuous gradient performance of functionally graded parts can be improved.
  • the specific method is: in the printing process of each layer, the printed layer (forming structure layer) is not completely cured (ie pre-cured); after the current layer is printed, the pre-cured printing layer is fully cured, and the current layer is fully cured. Pre-cured. After the introduction of a two-step curing process, precise control of the bond strength and gradient properties between layers can be achieved. It solves the problems of poor bonding strength between layers, poor continuous gradient performance and poor accuracy in the prior art.
  • FIG. 1 is a schematic structural diagram of a printing apparatus for printing a constrained sacrificial layer using a material extrusion or jet forming process according to one or more embodiments of the present invention
  • FIG. 2 is a schematic diagram of printing using material jet forming for constrained sacrificial layer printing according to one or more embodiments of the present invention
  • FIG. 3 is a schematic diagram of the structure of the printing nozzle for the constrained sacrificial layer printing using a material extrusion or jet forming process according to one or more embodiments of the present invention
  • FIG. 4 is a schematic structural diagram of a passive hybrid printing nozzle according to one or more embodiments of the present invention.
  • FIG. 5 is a schematic structural diagram of an active hybrid module according to one or more embodiments of the present invention.
  • FIG. 6 is a schematic structural diagram of a printing device employing a traditional FDM printing process for constrained sacrificial layer printing according to one or more embodiments of the present invention
  • FIG. 7 is a schematic diagram of printing using a conventional FDM process for constrained sacrificial layer printing according to one or more embodiments of the present invention.
  • FIG. 8 is a schematic structural diagram of a conventional FDM printing process for constrained sacrificial layer printing according to one or more embodiments of the present invention, and a constrained sacrificial layer printing nozzle;
  • FIG. 9 is a process flow diagram of material extrusion or spray forming for constrained sacrificial layer printing according to one or more embodiments of the present invention.
  • FIG. 10 is a flow chart of a conventional FDM printing process for constrained sacrificial layer printing according to one or more embodiments of the present invention
  • Constrained sacrificial layer feeding module 2. Anti-settling feeding module I, 3. Anti-settling feeding module II, 4. Active mixing module, 5. Air pressure regulating valve table I, 6. Air pressure regulating valve table II , 7. Z-axis motion module, 8. Connection frame VII, 9. Connection frame I, 10. Connection frame II, 11. X-axis motion module, 12. Positive pressure air circuit, 13. High voltage DC power supply, 14. Auxiliary Observation camera module, 15. Passive hybrid printing module, 16. Base, 17. Printing platform, 18. Constraint sacrificial layer printing module, 19. UV curing module, 20. Bottom plate, 21. Bracket I, 22. Y-axis motion module , 23. FDM wire feeding module, 24. FDM printing module, 25. Bracket II;
  • Constrained sacrificial layer storage bucket 180106.
  • Constrained Sacrificial layer nozzle heating block 180107.
  • Constrained sacrificial layer printing nozzle 1802. Connection frame IV, 1803. Cylinder module II, 1901. UV curing unit, 1902. Connection frame V, 1903. Cylinder module III, 2401. FDM printing Nozzle, 240101. Stepper motor, 240102. Wire feed port, 240103. Wire, 240104. Heat sink, 240105. Cooling fan, 240106.
  • FDM nozzle heating block 240107.
  • FDM printing nozzle 2402. Connection frame VIII, 2403 .Cylinder Module IV.
  • This embodiment provides a 3D printing device for the integrated manufacture of functionally graded materials and three-dimensional structures, as shown in Figure 1, including an XYZ three-axis module, an anti-settling feeding module I2 (high solid content materials are stored for a long time without sedimentation) ), anti-settling feeding module II3 (high solid content materials are stored for a long time without settlement), constrained sacrificial layer feeding module 1, active mixing module 4, positive pressure gas circuit 12, high voltage DC power supply 13, auxiliary observation camera module 14, passive Hybrid printing module 15, constraining sacrificial layer printing module 18, UV curing module 19, base plate 20, printing platform 17, base 16, etc.;
  • the XYZ three-axis module includes an X-axis motion module 11, a Y-axis motion module 22, and a Z-axis motion module 7, and the Y-axis motion module 22 is fixed above the bottom plate 20 through the bracket I21.
  • Two Y-axis movement modules 22 are provided, and the two Y-axis movement modules 22 are arranged at a certain distance along the length direction of the bottom plate 20 .
  • a bracket II25 is installed above the Y-axis motion module 22, and the X-axis motion module 11 is installed on one side of the bracket II25; the Z-axis motion module 7 is connected to the X-axis motion module 11 through the connecting frame I9.
  • the printing platform 17 is fixed on the base plate 20 through the base 16, and the printing platform 17 corresponds to the lower part of the printing module.
  • the printing platform 17 has a leveling function and an electric heating function.
  • the heating device provided on the printing platform 17 is an electric heating rod or an electric heating sheet, and the heating temperature range is 20-200°C.
  • the flatness of the printing platform is not less than ⁇ 5 ⁇ m, and the leveling method can be realized by the prior art, which will not be repeated here.
  • the X-axis motion module 11 and the Y-axis motion module 22 adopt a gantry structure, and the motion platform working stroke of the X-axis motion module 11 and the Y-axis motion module 22 is 0-900 mm, and the positioning accuracy is not low. Within ⁇ 5 ⁇ m, repeat positioning accuracy is not less than ⁇ 3mm, and the maximum speed is 500mm/s.
  • the Z-axis motion module 7 has a working stroke of 0-300mm, a positioning accuracy of not less than ⁇ 3 ⁇ m, a repeat positioning accuracy of not less than ⁇ 1 ⁇ m, and a maximum speed of 300mm/s.
  • the Z-axis motion module 7 is connected to the connection frame II10 through the connection frame VII8, and the UV curing module 19, the constraint sacrificial layer printing module 18, the passive hybrid printing module 15, and the auxiliary observation camera module 14 are sequentially installed on the connection frame II10.
  • the passive mixing printing module 15 is connected to the active mixing module 4 and the positive pressure air circuit 12 through the pipeline, and the active mixing module 4 is connected to the anti-settling feeding module I2 and the anti-settling feeding module II3;
  • the sacrificial layer supply module 1 and the positive pressure gas path 12 .
  • the pipeline connecting the passive hybrid printing module 15 with the positive pressure air path 12 is installed with the air pressure regulating valve table II6, and the pipeline connecting the constraining sacrificial layer printing module 18 with the positive pressure air path 12 is installed with the air pressure regulating valve table I5.
  • the constraining sacrificial layer printing module 18 and the passive hybrid printing module 15 are connected to the positive pole of the high-voltage DC power supply 13.
  • the high-voltage DC power supply 13 can output DC high voltage, output AC high voltage and output pulse high voltage, and can set a bias voltage,
  • the set bias voltage range is 0-2kV continuously adjustable, DC high voltage 0-5kV, output pulse DC voltage 0- ⁇ 4kV continuously adjustable, output pulse frequency 0-3000Hz continuously adjustable, AC high voltage 0- ⁇ 4kV.
  • the UV curing module 19 includes a UV curing unit 1901, a connecting frame V1902, and a cylinder module III1903.
  • the UV curing unit 1901 is connected to the cylinder module III1903 through the connecting frame V1902, and the cylinder module III1903 is installed on the connecting frame II10. side end.
  • the auxiliary observation camera module 14 includes an auxiliary observation camera 1401 and a connecting frame VI 1402. The auxiliary observation camera 1401 is installed on the other end of the connecting frame II10 through the connecting frame VI 1402.
  • the constrained sacrificial layer printing module 18 includes a constrained sacrificial layer printing nozzle 1801, a connecting frame IV1802, and a cylinder module II 1803, and the constrained sacrificial layer printing nozzle 1801 is connected to the positive electrode of the high-voltage DC power supply 13; the constrained sacrificial layer printing nozzle 1801 is connected by connecting The frame IV1802 is connected to the cylinder module II1803, and the cylinder module II1803 can drive the constraining sacrificial layer printing nozzle 1801 to move up and down.
  • the constrained sacrificial layer printing nozzle 1801 is used to print the constrained sacrificial layer material, including the constrained sacrificial layer feed port 180101, the constrained sacrificial layer positive pressure air port 180102, the adapter 180103, the annular heater 180104,
  • the constraining sacrificial layer storage bucket 180105, the constraining sacrificial layer nozzle heating block 180106 and the constraining sacrificial layer printing nozzle 180107, the end of the constraining sacrificial layer storage bucket 180105 is connected to the constraining sacrificial layer printing nozzle 180107 through the constraining sacrificial layer nozzle heating block 180106, constraining the sacrificial layer
  • An annular heater 180104 is installed on the outer side of the storage tank 180105; an adapter 180103 is installed on the top of the constraining sacrificial layer storage tank 180105, and the top of the constraining sacrificial layer storage tank 180105 is connected to the constraining
  • the positive pressure air port 180102 of the constraining sacrificial layer is connected to the positive pressure air path 12 through a hose, and the air pressure regulating valve table I5 is installed on the hose.
  • the constraining sacrificial layer feeding port 180101 is connected to the constraining sacrificial layer feeding module 1 . Extrusion of the constraining sacrificial layer material only by the positive pressure control unit is defined as the extrusion printing mode, combined with the positive pressure control unit and the high voltage DC power supply 13, the constraining sacrificial layer is jet-formed and defined as the jet printing mode.
  • the constraining sacrificial layer feeding module 1 adopts a precision syringe pump, in which the cartridge can be heated, and is connected to the constraining sacrificial layer feeding port 180101 through a heatable pipe and an adapter. It can be understood that, in other embodiments, the constraining sacrificial layer feeding module 1 may also use a micro-syringe pump, a peristaltic pump, or the like.
  • the constrained sacrificial layer printing nozzle 180107 adopts a Musashi nozzle, which is connected to the positive electrode of the high voltage DC power supply 13 through a wire.
  • the Musashi nozzle forms a strong electric field with the substrate placed on the printing platform 17, which drives the ejection and deposition of the material on the substrate.
  • the passive hybrid printing module 15 includes a passive hybrid printing nozzle 1501, a connecting frame III1502, and a cylinder module I1503.
  • the passive hybrid printing nozzle 1501 is connected to the cylinder module I1503 through the connecting frame III1502, and the cylinder module I1503 can drive the passive hybrid printing nozzle 1501. Moving up and down.
  • the cylinder module I1503, the cylinder module II1803, and the cylinder module III1903 can be replaced with an electric displacement stage, a linear positioning platform, a hydraulic cylinder, and the like.
  • the passive mixing printing nozzle 1501 includes a passive mixing feeding port 150101, a passive mixing positive pressure air port 150102, a static mixer 150103, and a passive mixing printing nozzle 150104.
  • the passive mixing printing nozzle 150104 is installed at one end of the static mixer 150103.
  • the passive mixing feeding port 150101 and the passive mixing positive pressure air port 150102 are installed on the other end of the static mixer 150103;
  • the passive mixing feeding port 150101 is connected to the active mixing module 4 through a hose, and the passive mixing positive pressure air port 150102 is connected to the active mixing module 4 through a hose.
  • the pipe is connected to the positive pressure air circuit 12 .
  • the materials mixed by the active mixing module 4 enter the static mixer 150103, and the static mixer 150103 realizes two functions: first, to further uniformly mix the printing materials delivered by the active mixing module 4; second, to ensure that the printing materials are continuously and stably provided for printing Printheads to ensure the realization and stability of continuous functionally graded materials/and structures printing.
  • the positive pressure air path 12 is used to realize the stable and uniform delivery of the printing material from the static mixer 150103 to the end of the printing nozzle.
  • the passive hybrid printing nozzle 1501 includes but is not limited to metal nozzles, plastic nozzles, glass nozzles, silicon nozzles, etc., and the inner diameter of the nozzle is 0.5 ⁇ m-1 mm.
  • the passive hybrid printing nozzle 1501 uses an extrusion or jet forming process to print the functionally graded material.
  • the working range of the positive pressure gas path 12 is 0.1bar-1Mpa.
  • the active mixing module 4 includes a stepping motor 401, a vibrating mixing chamber 405, and an active stirring screw 406.
  • the active stirring screw 406 is arranged inside the vibrating mixing chamber 405, and the axes of the two are coincident. ;
  • Vibration mixing chamber 405 has the function of ultrasonic vibration.
  • the active stirring screw 406 is connected to the stepping motor 401, and the stepping motor 401 is fixed on the outer side of one end of the vibrating mixing chamber 405; the active stirring screw 406 rotates under the driving action of the stepping motor 401, which can mix the materials evenly and extrude the vibrating mixture.
  • the active stirring screw 406 adopts a common stirring screw structure.
  • the other end of the vibrating mixing chamber 405 is a material outlet 404, and the material outlet 404 is connected to the passive mixing feeding port 150101 of the passive mixing printing nozzle 1501 through a hose.
  • the vibrating mixing chamber 405 is arranged vertically, the discharge port 404 is located at the top end, and the stepper motor 401 is located at the bottom end.
  • the discharge port 404 has a frustum-shaped structure.
  • the side of the vibrating mixing chamber 405 is provided with a feeding port I402 and a feeding port II403, the feeding port I402 is connected with the anti-settling feeding module I2, and the feeding port II403 is connected with the anti-settling feeding module II3 .
  • the printing material I enters the vibrating mixing chamber 405 from the feeding port I402, and the printing material II enters the vibrating mixing chamber 405 from the feeding port II403, and the active stirring screw 406 is driven by the stepping motor 401 to rotate, so that the material is in the vibrating mixing chamber.
  • Mixing is carried out in 405, and as the mixing progresses, the mixed material is sent from the material storage port 404 to the connecting hose, and then enters the passive mixing printing nozzle 1501 through the hose.
  • the anti-settling feeding module I2 and the anti-settling feeding module II3 can be electric stirring pressure barrels, etc., and are connected to the feeding port of the vibrating mixing chamber 405 through hoses and pipe joints.
  • the anti-settling feeding module I2 is used to place the printing material I, and the printing material I is the first printing raw material, which includes but is not limited to the following materials: photosensitive resin, PDMS, hydrogel, thermosetting epoxy resin, etc. or thermally cured materials.
  • Nanomaterials such as SiO 2 , Al 2 O 3 , TiO 2 , SiC, ZrO 2 , graphene, carbon nanotubes and other powder or granular materials.
  • the size of the micro-nano material is 30nm-50 ⁇ m.
  • the constraining sacrificial layer feeding module 1 is used to place the printing material III, and the printing material III is the third printing raw material.
  • the third printing raw material includes but is not limited to the following materials: various water-soluble materials are preferred. materials such as PVA, etc.
  • the method of uniform mixing of three-level materials is adopted to solve the problems of material agglomeration and uneven mixing, and realize the efficient mixing of two or more materials and the printing of continuous gradient materials.
  • the first level of mixing is to fully premix the printing material II (the composite material after the first printing raw material and the second printing raw material are uniformly mixed), and use surface modification (to avoid agglomeration, especially nanoscale fillers and high solid content) Filler, there is a serious agglomeration phenomenon), ultrasonic vibration or ball milling and other processes to achieve full and even mixing of the filler and the liquid matrix material.
  • the second-stage mixing realizes the second-stage mixing of materials through screw mixing, so that the printing material I and the printing material II are continuously and stably mixed uniformly in the vibrating mixing chamber 405 .
  • the third-stage mixing realizes the third-stage mixing of the materials by means of vibration. Finally, it is sent to the passive mixing nozzle to achieve continuous and stable printing. In this way, after the multi-stage mixing of the material, it is ensured that the printing material reaching the nozzle has a better continuous functional gradient performance.
  • the optimized process window is applicable in a very wide range.
  • Using the constrained sacrificial layer structure can ensure that the thickness of each layer of the printed functionally graded material/structure is the set thickness, regardless of whether it is in the low-content filler functionally graded region or the high-content filler functionally graded region for a single functionally graded part printed , using the constrained sacrificial layer structure can ensure the same thickness (or set variable thickness, or adaptive thickness), especially for the same print in different areas, the same batch, and different batches, the printed energy gradient The parts have good consistency.
  • Embodiment 2 is a diagrammatic representation of Embodiment 1:
  • This embodiment provides a 3D printing method for the integrated manufacture of functionally graded materials and three-dimensional structures.
  • the 3D printing equipment described in the first embodiment is used, and the material injection molding process is used for the printing of the constrained sacrificial layer, as shown in FIG. 9 , including the following step:
  • Model information processing Determine the geometric information of each layer (path, layer thickness, etc.), and generate a print data file;
  • Pre-print processing complete the preparatory work before printing. Determine the material ratio, and preprocess printing material I and printing material II respectively; set the printing feeding speed, printing speed, bottom plate temperature, nozzle temperature, air pressure, voltage, etc.;
  • Post-print processing Close each device and module, remove the formed functional gradient structure containing the auxiliary support structure after printing, and then separate the auxiliary support structure from the functional gradient sample (peel, dissolve in special solution or dissolve in hot water, etc.).
  • This embodiment takes the photosensitive resin RGD835/Al 2 O 3 functionally graded ceramic insulator as an example to realize the working method of integrated manufacturing of continuous functionally graded materials and complex three-dimensional structures, and describes the specific process steps:
  • Step 1 Print data file preparation. According to the structural requirements of the printed part, it is determined that the concentration of Al 2 O 3 in the ceramic insulator changes continuously from one side to the other side of 0%-50%, the printing information of each layer is determined, and the printing nozzle of the constraining sacrificial layer 180107 adopts the Musashi nozzle, the inner diameter is 250 ⁇ m , the printing height is 0.1mm, and the line spacing is set to 100 ⁇ m; the passive hybrid printing nozzle 150105 adopts metal stainless steel nozzle, model 21G (outer diameter is 810 ⁇ m, inner diameter is 510 ⁇ m), printing height is 0.05mm, and line spacing is 300 ⁇ m.
  • Step 2 Pre-print processing.
  • the printing material of the constraining sacrificial layer is preferably water-soluble PVA, put it into the constraining sacrificial layer feeding module 1, and the barrel in the constraining sacrificial layer feeding module 1 can be heated , and transport the printing material to the constraining sacrificial layer storage tank 180105 through the heatable pipes and adapters, and then use the positive pressure of the air circuit and the high-voltage DC power supply 13 to form a strong electric field between the nozzle and the substrate placed on the printing platform 17 to drive the
  • the printing material is jet-deposited from the Musashi nozzle.
  • the pure solution of photosensitive resin RGD835 is the printing material I; the configuration of the variable-component printing solution is carried out, and the photosensitive resin RGD835/Al 2 O 3 with 50% Al 2 O 3 content is prepared by ultrasonic and ball mill mixed solution, the Al 2 O 3 particles are uniformly dispersed in the photosensitive resin RGD835 solution, and then vacuumized to make a high-concentration photosensitive resin RGD835/Al 2 O 3 mixed solution as the printing material II.
  • Step 3 Continuous functional gradient structure printing.
  • (3-1) Feeding, based on the printing data information and program information of each layer, set the feeding speed and feeding time, and transport the printing material PVA of the constraining sacrificial layer to the constraining sacrificial layer storage bucket 180105; according to the materials of each component Requirements and material ratio, accurately set the feeding speed and time of the feeding module, deliver the required printing material I and printing material II (volume ratio or weight ratio) to the active mixing module 4, and send it to the passive mixing printing after the mixing is completed.
  • the printing nozzle 1801 is lowered to the printing station IIB, and the air pressure regulating valve table 5 is used to precisely adjust the air pressure (positive pressure 50kpa) of the constrained sacrificial layer.
  • the cylinder module II1803 drives the constraining sacrificial layer printing nozzle 1801 to ascend to the initial printing station IIC (in-situ).
  • the functional gradient layer material is printed on the constrained sacrifice. within the layer.
  • the cylinder module I1503 drives the passive hybrid printing nozzle 1501 to rise to the initial printing station IC (in-situ).
  • the passive hybrid printing nozzle 1501 and the constrained sacrificial layer printing nozzle 1801 cooperate with each other to alternately eject the printing material according to the process parameters, printing path and printing order set by the printing program, and drive the driving according to the geometric information.
  • XYZ three-axis motion first print the sacrificial layer, and then print the functional gradient structure layer for geometric forming.
  • Step 4 After printing one layer of the constraint sacrificial layer, the Z-axis rises by 0.1mm; after each layer of passive mixing is printed, the Z-axis rises by 0.05mm, and after printing one layer, turn on the UV curing unit 1901, Control the UV curing unit 1901 to move to the printing station IIIA, the cylinder module 1903 drives the UV curing unit 1901 to descend to the printing station IIIB, cure the mixed liquid of the layer, cure for 20s, and cure the material of the printing layer about 90%, pre- After curing and forming, the cylinder module 1903 drives the UV curing unit 1901 to ascend to the initial printing station III C (in-situ).
  • the UV curing unit 1901 uses the UV curing unit 1901 to cure for 20s to completely cure the printing material of the previous layer, and the material of this layer is cured about 90%; as the number of layers increases, change the anti-settling
  • the feeding speed of the feeding module I2 and the anti-settling feeding module II3 makes the concentration of Al 2 O 3 change continuously.
  • Step 5 Repeat the above operation to complete all printing.
  • Step 6 Post-Print Processing.
  • This embodiment introduces a two-step curing strategy, and with the assistance of constraining the sacrificial layer structure, the printing efficiency can be effectively improved, and the interlayer bonding strength and continuous gradient performance of the functionally graded part can be improved.
  • the specific method is: during the printing process of each layer, the printed layer (forming structure layer) is not fully cured (ie pre-cured); after the current layer is printed, the pre-cured printing layer is fully cured, and the current layer is fully cured. Pre-cured. After the introduction of a two-step curing process, precise control of the bond strength and gradient properties between layers can be achieved. It solves the problems of poor bonding strength between layers, poor continuous gradient performance and poor accuracy in the prior art.
  • This embodiment provides a 3D printing equipment for the integrated manufacture of functionally graded materials and three-dimensional structures, as shown in Figures 6-8, including XYZ three-axis modules, anti-settling feeding module I2 (high solid content material for a long time Storage without sedimentation), anti-settling feeding module II3 (high solid content materials are stored for a long time without sedimentation), active mixing module 4, positive pressure gas circuit 12, high voltage DC power supply 13, auxiliary observation camera module 14, passive hybrid printing module 15, FDM printing module 24, FDM wire feeding module 23, UV curing module 19, base plate 20, printing platform 17, base 16, etc.;
  • the constrained sacrificial layer printing module 18 in the first embodiment is replaced with an FDM printing module 24 , and the FDM printing module 24 is connected to the FDM wire feeding module 23 .
  • the printing material III is placed in the FDM wire feeding module 23, and the printing material III is ABS, PLA, TUP, etc., which are commonly used in FDM.
  • the FDM printing material adopts PLA.
  • the FDM wire feeding module 23 feeds the wire (thermoplastic filamentous material) 240103 into the FDM printing module 24 .
  • the FDM printing module 24 includes an FDM printing nozzle 2401, a connecting frame VIII 2402, and a cylinder module IV2403.
  • the FDM printing nozzle 2401 is connected to the cylinder module IV2403 through the connecting frame VIII 2402, and the cylinder is connected to the cylinder module IV2403.
  • the module IV2403 is installed on the side of the connecting frame II10.
  • the FDM printing nozzle 2401 includes a stepping motor 240101, a wire supply port 240102, a heat sink 240104, a cooling fan 240105, an FDM nozzle heating block 240106, an FDM printing nozzle 240107, and a wire supply port 240102 for the wire material 240103 to pass through, step
  • the feeding motor 240101 is used to provide the conveying power for the wire 240103.
  • the FDM nozzle heating block 240106 is installed above the FDM printing nozzle 240107 for melting the filament 240103.
  • the stepping motor 240101 transports the prepared printing material from the FDM wire feeding module 23 to the FDM printing nozzle 240107 of the FDM wire feeding module 24 through the wire feeding port 240102. Under the action of the FDM nozzle heating block 240106, the printing material is melted into Semi-liquid, the melted printing material is squeezed out. Since the FDM printing module 24 continuously prints, the temperature will be high for a long time, so the heat sink 240104 and the cooling fan 240105 are required to dissipate and cool down the stepping motor 240101 and the entire FDM printing module 24 .
  • Embodiment 4 is a diagrammatic representation of Embodiment 4:
  • This embodiment provides a 3D printing method for the integrated manufacture of functionally graded materials and three-dimensional structures.
  • the 3D printing device described in the third embodiment is used, and the traditional FDM printing process is used for the printing of the constrained sacrificial layer, as shown in FIG. 10 .
  • Model information processing Determine the geometric information of each layer (path, layer thickness, etc.), and generate a print data file;
  • Pre-print processing complete the preparatory work before printing. Determine the material ratio, preprocess the printing material I and printing material II; set the printing speed, temperature, air pressure, voltage, etc. of the gradient material; set the feeding speed of the FDM printing module (speed of the stepping motor 240101), printing speed, nozzle temperature, etc.;
  • Post-print processing Close each device and module, remove the formed functional gradient structure containing the auxiliary support structure after printing, and then separate the auxiliary support structure from the functional gradient sample (peel, dissolve in special solution or dissolve in hot water, etc.).
  • the functional gradient thermal interface of a BN/PDMS mixed solution with a particle size of 1 ⁇ m and a BN/PDMS mixed liquid with a particle size of 20 ⁇ m is taken as an example to realize the working method of integrated manufacturing of continuous functional gradient materials and complex three-dimensional structures, and the specific process is described. Process steps:
  • Step 1 Print data file preparation. According to the structural requirements of the printed part, it is determined that the concentration change of the functional gradient thermal interface from one side to the other side is the transition of the BN/PDMS mixture with a BN content of 40% with a particle size of 1 ⁇ m to a BN/PDMS mixture with a BN content of 40% with a particle size of 20 ⁇ m.
  • the PDMS mixture is then transitioned to a continuous gradient change of the BN/PDMS mixture with a BN content of 40% by 1 ⁇ m, and the printing information of each layer is determined; FDM printing nozzle 240107, inner diameter 400 ⁇ m, printing height 0.2mm, line spacing set to 350 ⁇ m
  • the passive hybrid printing nozzle 150104 adopts metal stainless steel nozzle, model 21G (outer diameter is 810 ⁇ m, inner diameter is 510 ⁇ m), printing height is 0.2mm, and line spacing is 300 ⁇ m.
  • Step 2 Print preprocessing.
  • the FDM printing material is selected as thermoplastic PLA, put it into the FDM wire feeding module 23, and sent to the FDM printing nozzle 2401 from the wire feeding port 240102, under the action of the nozzle heating block 240106 , melts the printing material into a semi-liquid state and extrudes it.
  • the printing material I (the BN/PDMS mixture with a BN content of 40% in the particle size of 1 ⁇ m) and the printing material II (the BN/PDMS mixture with a BN content of 40% in 20 ⁇ m) respectively in the anti-settling feeding module I2 and the anti-settling.
  • the printing material I and the printing material II are uniformly stirred and vibrated in the vibrating mixing chamber 405 by the screw, and then sent to the static mixer, and the static mixing is carried out by the positive pressure air circuit 12 and the high voltage DC power supply 13.
  • the material in the machine is stably and evenly sent to the printing nozzle, and the evenly mixed printing material is printed out from the stainless steel nozzle.
  • Step 3 Continuous functional gradient structure printing.
  • (3-1) Feeding, based on the printing data information and program information of each layer, set the wire feeding speed (stepping motor 240101 speed) and feeding time, and send the FDM printing wire PLA from the wire feeding port to the FDM printing nozzle ;According to the material requirements and material ratio of each component, accurately set the feeding speed and time of the feeding module, and deliver the required printing material I and printing material II (volume ratio or weight ratio) to the active mixing printing module 4, After the mixing is completed, it is sent to the passive mixing print head.
  • (3-2) Print the constraining sacrificial layer use the FDM wire feeding module 23 to transport the FDM printing filament PLA to the FDM printing nozzle 2401 through the wire feeding port 240102, and then use the cylinder module IV2403 to drive the FDM printing nozzle 2401 down to the printing process Position IIB, extrude the printing filament from the FDM printing nozzle 240107, and print the constraining sacrificial layer of the component according to the path set by the program; after the constraining sacrificial layer is printed, the cylinder module IV2403 drives the FDM printing nozzle 2401 to rise to the initial stage Printing station IIC (in-situ).
  • the passive hybrid printing nozzle 1501 and the FDM printing nozzle 2401 cooperate with each other to alternately eject the printing material according to the process parameters, printing path and printing order set by the printing program, and drive the XYZ three according to the geometric information. Axis movement, first print the sacrificial layer, and then print the functional gradient structure layer for geometric forming.
  • Step 4 After printing one layer of the constraint sacrificial layer, the Z-axis rises by 0.2mm; after each layer of passive mixing is printed, the Z-axis rises by 0.2mm, and after printing one layer, use the printing platform 17 temperature to cure After 30s, the material of the printing layer is cured by about 80%. After the second layer of the mixed solution is printed, the temperature of the printing platform 17 is used to cure for 30s, and the printing material of the upper layer is completely cured, and the material of this layer is cured for 80 seconds. During the printing process, as the number of layers increases, the temperature of the printing platform 17 should also increase appropriately, and when the printing reaches a suitable height, the upper UV curing unit 1901 is turned on to cure the top of the structure. As the number of layers increases, the feeding speed of the anti-settling feeding module I2 and the anti-settling feeding module II3 is changed, so that the concentration of BN changes continuously.
  • Step 5 Repeat the above operation to complete all printing.
  • Step 6 Post-processing.

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Abstract

功能梯度材料和三维结构一体化制造的3D打印设备及方法，包括主动混合模块（4）、被动混合打印模块（15）、约束牺牲层打印模块（18），主动混合模块（4）输入端与多个防沉降供料模块（2,3）相连，主动混合模块（4）输出端与被动混合打印模块（15）相连；被动混合打印模块（15）、约束牺牲层打印模块（18）安装于XYZ三轴模组一侧；约束牺牲层打印模块（18）连接约束牺牲层供料模块（1），在约束牺牲层材料的辅助作用下能够打印形成复杂功能梯度三维结构；主动混合模块（4）包括振动混料室（405）、安装于振动混料室（405）的主动搅拌螺杆（406），进入主动混合模块（4）的多种材料在超声振动及主动搅拌螺杆（406）搅拌作用下均匀混合，并通过主动搅拌螺杆（406）挤出。该打印设备及方法能够实现连续功能梯度材料和复杂三维结构一体化制造，打印效率高、成本低。

Description

功能梯度材料和三维结构一体化制造的3D打印设备及方法 技术领域
本发明涉及增材制造和功能梯度材料/结构制造技术领域，尤其涉及一种功能梯度材料和三维结构一体化制造的3D打印设备及方法。
背景技术
功能梯度材料(Functionally Gradient Material,简称FGM)是指在材料的制备过程中，采用先进的复合技术，使材料的微观要素(包括材料组分和微观结构),在某特定方向上呈连续(或准连续)的梯度变化,从而使材料的宏观性能也在同一方向上呈连续(或准连续)梯度变化的一种非均质复合材料。功能梯度材料的显著特点是在传统的复合材料中加上材料含量配比成梯度变化的中间过渡层，从而使材料的物理性能呈渐变形式，避免或缓解传统复合材料由于物性差异太大而在使用过程中所产生诸如应力集中、开裂及剥落等缺陷。此外，功能梯度材料还具有非常好的可设计性，通过有针对性地改变各组分材料体积含量或者微结构的空间分布，以达到优化结构内部应力分布、满足不同部位对材料使用性能的要求。作为一种全新的先进材料，它既解决了复合材料的界面应力问题，同时又保持了材料的复合特性，以及性能的裁剪特性和多功能性。由于其优异的物化性能，功能梯度材料目前已经被应用于航空航天、生物医疗、核工程、能源、电磁、光学、柔性电子、可穿戴设备、软体机器人、高电压等诸多领域和行业，显示出广阔的工程应用前景。
根据功能梯度材料所含有材料成分的不同，功能梯度材料分为：(1)无机功能梯度材料，主要包括金属/陶瓷、金属/非金属、金属/金属和陶瓷/非金属等；(2)聚合物功能梯度材料，主要包括高聚物/高聚物、高聚物/陶瓷、高聚物/金属和高聚物/无机填料等，但是目前聚合物功能梯度材料的研究与开发还主要集中在高聚物/高聚物和高聚物/无机填料这两大类。聚合物功能梯度材料(PGM)主要指的是基体材料为高分子材料的一类功能梯度材料总称，与无机功能梯度材料相比，聚合物功能梯度材料具有更为广泛的工程化应用。
据发明人了解，功能梯度材料现有的主要制备方法：化学气相沉积法、物理蒸镀法、等离子喷涂法、自蔓延高温合成法、粉末冶金法、离心成形法、注浆成形法、化学气相渗透法和电解析出法等。但是上述这些传统的制备方法只能用来制造准连续(分层梯度，无法实现连续功能梯度材料的制备)功能梯度材料，成形的是结构较简单的功能梯度材料和零件，难以实现两种以上材料的均匀混合(尤其是基体材料是液体材料，填料是纳米材料)，无法实现连续梯度复杂形状零件的成形，尤其是完全无法实现连续功能梯度材料和复杂三维结构一体化制造，而且成形过程复杂，效率低，成本高。近年出现的增材制造技术(3D打印)为功能梯度材料和功能梯度结构件的制造提供了一种全新的技术解决方案，尤其是多材料和多尺度3D打印技术为连续功能梯度材料和复杂三维结构制件(零件或者产品)一体化制造提供了一种理想的解决方案。
根据现有国内外已经公开的研究成果和信息，已经提出用于制造功能梯度材料/结构制件的3D打印技术和工艺主要包括：定向能量沉积(LENS)、激光熔覆、熔融沉积成型(FDM)、聚合物喷射(Polyjet)、粉末床熔融、墨水直写(DIW)等，但是，据发明人研究后，发现现有的这些3D打印技术在制造功能梯度材料/结构件时都还存在许多的缺陷和不足：(1)对于聚合物基功能梯度材料/结构制件，目前还无法实现连续功能梯度材料和复杂三维结构一体化制造，尤其是无法实现连续功能梯度材料和复杂三维结构的一体化制造以及功能与性能精准调控，例如特高压行业亟需的功能梯度盆式绝缘子，目前还没有一种工艺能满足实际工程制造的要求(即要求连续功能梯度介电常数，又要求较为复杂的盆状结构几何形状)。(2)成形的材料受限，尤其是对于目前工程界广泛使用的光敏树脂(第一材料)/微纳米材料填料(第二材料) 体系，难以获得高性能功能梯度制件。通常基体材料的粘度越小，所能添加的固相微纳米填料越高，能够实现的功能梯度就越大，功能梯度制件的性能就越好。然而，低粘度的基体材料(没有添加填料或者填料的含量较低)在打印开始阶段存在严重的摊铺(流动浸润)特性，难以实现精准几何形状控制和表面粗糙度差，成形件的几何形状精度和表面粗糙度较差。此外，当添加的第二材料固相含量较高或者添加的是较大颗粒尺寸的第二材料，存在严重的材料沉降，无法实现稳定的打印，难以确保连续梯度性能。(3)打印功能梯度制件的精度差，现有制造功能梯度材料/结构制件的3D打印技术，还无法实现微尺度和亚微尺度精度的功能梯度材料/结构制件的制造。一方面从挤出/喷射出打印材料的最小量(微滴、细丝)还较大，尤其是对于分层厚度无法精准控制(填料或者第二材料的组分不断不发生变化，工艺参数的实时调整无法确保，固化控制一致性差)。(4)现有各种3D打印技术制备的功能梯度材料/结构制件，层间的结合强度和连续梯度性能差，由于打印材料的组分不断变化，难以实现精准的快速固化(尤其是UV固化树脂基基体材料，随着填料(第二材料)的不断增大，高固含量的区域与低固填料的区域固化时间和功率有着非常大的差异，现有的工艺所有层的打印通常使用相同的固化功率和固化时间，这将导致低固填料的区域出现过固化，层间结合强度差，高固含量的区域存在固化不充分，层间结合强度也较差)。(5)打印的功能梯度制件一致性差，无法满足实际生产所要求的制件具有非常高一致性的严格要求，难以用于实际生产(实际批量化制造过程中，要求制造的所有零件具有非常好的几何尺寸和性能的一致性，同一件不同区域、批次和批间打印件的一致性好)。功能梯度材料打印过程中，材料的成分不断发生变化，这给打印带来很大的挑战。现有3D打印工艺优化的参数，均是针对具体材料，即使是复合材料，材料的成分/组分在打印过程中不会发生变化。但是，对于功能梯度材料的打印，材料的组分/成分不断发生变化，尤其是固化的工艺参数以及影响流变等性能的参数不断发生变化，即使使用优化的工艺参数，也会导致打印的结构出现微小的变化，从而导致性能和几何结构以及表面质量不断发生变化，这就为打印件的一致性带来严重的挑战。例如，现有的技术(尤其对于光敏树脂基材料)由于没有完全固化，每层的材料厚度变化不均匀(由于打印液态光敏材料铺展程度的不确定性)，导致每层厚度以及内外几何形貌都会发生变化，每次打印件的一致性较差，无法满足实际生产要求。(6)各组分材料混合不均匀。现有的这些技术都没有提供专门的混料单元，导致混料不均匀，这导致无法制备出真正的高性能功能梯度材料/结构件。例如现有的LENS、激光熔覆、FDM等技术大都采用的是集成喷头/打印头结构，在集成喷头内完全无法实现多材料的均匀混合，尤其是LENS和激光熔覆材料是各组分材料喷射沉积后是在熔池内进行的混合，混合效果更差。聚合物喷射工艺采用的多喷头结构，同样是多种材料沉积后固化前才进行的混合，无法实现多组分材料完全均匀混合。粉末床熔融工艺制约其更无法实现材料的均匀混合(尤其对铺粉的送料方式)，而且存在材料浪费严重的问题。(7)现有的各种3D打印技术不能实现连续功能梯度材料/结构件的制造，只能实现准连续功能梯度材料/构件的制造，无法制备出真正意义上的功能梯度材料/构件。(8)现有功能梯度材料/结构3D打印技术，大多是简单二维或者2.5维结构一体化制造，还无法实现连续功能梯度材料和复杂三维结构一体化制造。(9)生产效率低，制造工艺稳定性差，例如LENS、激光熔覆、FDM等，由于打印过程中材料配比不断发生变化，打印工艺参数(激光器功率、喷头加热温度等)也必须做出相应的调整，导致整个打印过程工艺稳定性差，打印效率低；尤其是采用集成打印头结构，混料和打印功能集成于一体，对于送料、混料和打印必须保证严格的顺序和同步关系，否则难以成功打印出需要的功能梯度材料和成型结构，加工效率的改进受到很大的限制。(10)可供打印材料种类和形状受限，而且打印材料需要提前加工成需要的形状和尺寸。例如目前LENS和激光熔覆工艺适合的材料基本上是粉材和丝材，而且对于粉材和丝材的形状和几何尺寸也都有严格的限定；FDM目前适合材料是丝材，同样其几何尺寸也有较为严格的限定；聚合物喷射目前只适合粘度非常低光敏树脂材料；粉末床熔融适合的是粉状材料，其几何形状和尺寸有着更为 严格的限制。(11)每种制造技术对于适合成形材料也有较严格的限制，LENS、激光熔覆和粉末床熔融技术主要用于金属基功能梯度材料/结构制造，FDM主要是用于热塑性塑料基功能梯度材料/结构制造，Polyjet主要用于光固化树脂基功能梯度材料/结构制造。
发明人先前已经公开的一项发明专利(申请号：201910204814X，功能梯度材料和成型结构一体化制造的3D打印机及工作方法)公开了一种功能梯度材料和成型结构一体化制造的3D打印机及工作方法，主要适用于原材料均为固态(固体)，即粉末/颗粒状固体和粉末/颗粒状固体混合打印实现功能梯度材料和成型结构一体化制造，几何形状较为简单的功能梯度件制造。根据功能梯度结构3D打印原材料的不同，基于3D打印制造功能梯度材料/结构的方法分为三类：(1)原材料均为液体(液态)，即不同体积分数(或者质量分数)液液混合3D打印；(2)一种原材料是液体(液态)，另外一种是固体(粉末状或者颗粒状固态，而且能够均匀混合在第一种液态原材料中)，即不同体积分数(或者质量分数)液固混合3D打印；(3)原材料均为固态(固体，粉末状、颗粒状、丝材状等)，即不同体积分数(或者质量分数)固固混合3D打印。该发明专利无法实现前面两种材料体系功能梯度材料/结构件的打印。此外，由于从原材料进料端到打印喷头距离非常长，整个管路内储存的材料非常多，打印的滞后性非常严重，尤其无法实现小尺寸功能梯度材料/结构制件的，也难以实现复杂三维几何结构的制造。该发明专利完全无法实现前两类材料体系能梯度材料和成型结构的一体化制造。
发明人先前已经公开的另外一项发明专利(申请号：2020101020099，功能梯度材料与结构一体化制造的3D打印装置及打印方法)主要发明目的是用于实现液体(基体)与粉末状固体(增强相)的均匀混合，且可以有效去除液体与粉末状固体混合过程中产生的气泡，以保证3D打印产品的质量。主要用于离散功能梯度件的制造。针对的问题是在液体和固体粉末混合过程中，通常存在以下问题：(1)在混合过程中，粉末易于团聚，难以分散，是现有固-液混合的常见问题；(2)如果液体的粘度过高，在混合过程中会带入空气，容易出现气泡，固体粉末难以在液体中混合均匀；(3)不同配比的固-液混合材料在打印过程中实现供料、混料和挤出等动作，整个过程耗时短，要求响应速度快。例如，对于PDMS基功能梯度材料，PDMS的粘度大，固体纳米颗粒难以在PDMS液体中混合均匀，而且在混合过程中容易出现气泡，固体纳米颗粒分布不均匀以及产生的气泡都会严重影响3D打印产品的质量等。该项发明专利(申请号：2020101020099)虽然声称其能够实现连续梯度材料与复杂结构的一体化制造，实际上在混料工步，打印过程是停止的(混料过程中，真空泵动作，对混料室抽负压，去除混合物料中的气泡，维持一定时间后，控制阀打开，恢复常压，然后施加一定正压，打开高压电源，三维移动支架按照程序设定的X和Y方向的轨迹运动，进行打印成型该层结构的几何形状)，需要对混料室抽负压，去除混合物料中的气泡，此时，打印会出现停顿过程，无法实现连续功能梯度材料和复杂三维结构一体化制造。
此外，原材料是液体和粉末状固体混合打印实现连续功能梯度材料和成型结构一体化制造，在液体和固体混合过程中，还存在以下问题，(1)高固含量材料固体填料沉降严重，尤其是颗粒尺寸比较大时会出现混合不均匀、混合效率低等问题。(2)在混合过程中，粉末易于团聚，尤其是纳米材料，难以均匀分散。(3)如果液体的粘度过高，在混合过程中会带入空气，容易出现气泡，固体粉末难以在液体中混合均匀，会影响打印成品的质量；(4)不同配比的固-液混合材料是在打印过程中实现供料、混料、真空和挤出等动作，整个过程耗时短，要求响应速度快。例如，对于柔性电子领域，目前广泛使用的各种单材料柔性衬底越来越不能满足实际工程应用的需求。
发明内容
针对现有技术存在的不足，本发明的目的是提供一种功能梯度材料和三维结构一体化制造的3D打印设备及方法，适合聚合物基连续功能梯度材料和复杂三维结构一体化制造，尤其是能够实现原材料是高固 含量以及高粘度的连续功能梯度材料和复杂三维结构一体化制造，解决了打印较大尺寸制件，由于打印时间长或者高固含量材料以及包含微尺度填料的材料，导致极易出现打印原材料的填料沉降导致无法打印的难题，解决了连续功能梯度材料在打印过程中材料的成分/组分不断发生变化，导致传统3D打印方法无法解决的难题(一致性、层间结合性能、精准控形快速固化等)；拓展了适合打印材料的种类；提高了所得性能，更大的梯度范围，更好的层间的结合强度和连续梯度性能；提高打印的功能梯度制件的一致性；提高了打印功能梯度变化的灵活性；提高了打印效率；简化了连续功能梯度制件3D打印机的结构，降低了制造成本。
为了实现上述目的，本发明是通过如下的技术方案来实现：
第一方面，本发明的实施例提供了一种功能梯度材料和三维结构一体化制造的3D打印设备，包括主动混合模块、被动混合打印模块、约束牺牲层打印模块，所述主动混合模块的输入端与多个防沉降供料模块相连，用于实现主动混合多种材料；主动混合模块的输出端与被动混合打印模块相连，用于将主动混合后的材料接入被动混合打印模块进行静态混合；
所述被动混合打印模块、约束牺牲层打印模块安装于XYZ三轴模组一侧；所述约束牺牲层打印模块连接约束牺牲层供料模块，在约束牺牲层材料的辅助作用下能够打印形成复杂功能梯度三维结构；
其中，主动混合模块包括振动混料室、安装于振动混料室的主动搅拌螺杆，振动混料室能够进行超声振动；进入主动混合模块的多种材料在超声振动及主动搅拌螺杆搅拌作用下均匀混合，并通过主动搅拌螺杆挤出；
被动混合打印模块包括被动混合打印喷头、能够带动被动混合打印喷头上下移动的气缸模组I；约束牺牲层打印模块包括约束牺牲层打印喷头、能够带动约束牺牲层打印喷头上下移动的气缸模组II。
第二方面，本发明实施例还提供了一种功能梯度材料和三维结构一体化制造的3D打印设备，包括主动混合模块、被动混合打印模块、FDM打印模块，所述主动混合模块的输入端与多个防沉降供料模块相连，用于实现主动混合多种材料；主动混合模块的输出端与被动混合打印模块相连，用于将主动混合后的材料接入被动混合打印模块进行静态混合；
所述被动混合打印模块、FDM打印模块安装于XYZ三轴模组一侧；所述FDM打印模块连接FDM送丝模块，FDM送丝模块能够将丝材输送到FDM打印模块中；
其中，主动混合模块包括振动混料室、安装于振动混料室的主动搅拌螺杆，振动混料室能够进行超声振动；进入主动混合模块的多种材料在超声振动及主动搅拌螺杆搅拌作用下均匀混合，并通过主动搅拌螺杆挤出；
被动混合打印模块包括被动混合打印喷头、能够带动被动混合打印喷头上下移动的气缸模组I；FDM打印模块包括FDM打印喷头、能够带动FDM打印喷头上下移动的气缸模组IV。
作为进一步的实现方式，所述主动搅拌螺杆连接步进电机，主动搅拌螺杆沿振动混料室内部轴向安装；所述振动混料室一端设有出料口，出料口与被动混合打印喷头相连；振动混料室侧面设有多个用于连接防沉降供料模块的进料口。
作为进一步的实现方式，所述振动混料室侧面设有进料口I、进料口II，进料口I与防沉降供料模块I相连，进料口II与防沉降供料模块II相连；
防沉降供料模块I用于放置打印材料I，打印材料I为第一打印原材料，第一打印原材料采用光固化或者热固化材料；防沉降供料模块Ⅱ用于放置打印材料Ⅱ，打印材料Ⅱ为第一打印原材料和第二打印原材料的均匀混合液体；第二打印原材料采用微纳米材料。
作为进一步的实现方式，所述被动混合打印喷头包括静态混合器、被动混合打印喷嘴，被动混合打 印喷嘴安装于静态混合器一端，静态混合器另一端连接被动混合进料通口和被动混合正压气口；
所述被动混合进料通口通过软管连接主动混合模块，被动混合正压气口通过软管连接正压气路；被动混合打印喷嘴连接高压直流电源的正极。
作为进一步的实现方式，所述约束牺牲层打印喷头包括约束牺牲层储料桶，约束牺牲层储料桶一端安装约束牺牲层喷头加热块和约束牺牲层打印喷嘴，约束牺牲层储料桶另一端安装适配器，且约束牺牲层储料桶通过适配器与约束牺牲层进料通口和约束牺牲层正压气口相连接；约束牺牲层打印喷嘴连接高压直流电源的正极。
作为进一步的实现方式，还包括安装于XYZ三轴模组的UV固化模块、辅助观测相机模块，所述UV固化模块包括UV固化单元、能够带动UV固化单元上下移动的气缸模组III。
作为进一步的实现方式，所述被动混合打印喷头下方设置用于放置基材的打印平台，所述打印平台通过底座安装于底板上方，打印平台安装有加热装置，且打印平台能够调平。
第三方面，本发明实施例还提供了一种功能梯度材料和三维结构一体化制造的3D打印方法，采用所述的3D打印设备，包括：
步骤1：打印处理：
配制打印材料II，将第一打印原材料和第二打印原材料按照设计要求均匀混合；将打印材料Ⅰ放置到防沉降供料模块Ⅰ，打印材料II放置到防沉降供料模块Ⅱ，打印材料III放置到约束牺牲层供料模块或FDM送丝模块；
将打印平台加热到设定温度，约束牺牲层打印喷头或FDM打印喷头、被动混合打印喷头移动到打印工位IIA，其他模块处于打印使能状态；
步骤2：打印约束牺牲层：
气缸模组II或气缸模组IV带动约束牺牲层打印喷头或FDM打印喷头下降到打印工位IIB，启动约束牺牲层供料模块或FDM送丝模块，使用约束牺牲层打印喷头或FDM打印喷头按照设定路径完成约束层和支撑结构的打印；
步骤3：打印功能梯度层：
被动混合打印喷头移动到打印工位IA，气缸模组II带动被动混合打印喷头下降到打印工位IB；按照设定梯度比例，防沉降供料模块Ⅰ和防沉降供料模块Ⅱ分别向主动混合模块中的振动混料室进行供料，经过主动混合内的主动搅拌螺杆搅拌与振动混合后经静态混合器进一步均匀混合；在正压控制单元挤出力的控制下，功能梯度材料被挤出到打印喷嘴出料口处，按照设定路径完成该功能梯度层打印；打印的该功能梯度层材料在约束牺牲层内；
步骤4：功能梯度层固化：
UV固化单元移动到打印工位IIIA，气缸模组III带动UV固化单元下降到打印工位IIIB；按照设定时间，通过UV光固化或者加热固化对于打印完成的功能梯度层进行预固化成形；功能梯度层预固化成形后，气缸模组III带动UV固化单元上升到初始印工位III C；
步骤5：重复步骤2-4的操作，直到完成所有功能梯度层结构的打印；
当完成该层功能梯度层打印后，进行固化处理，对于上一层预固化的功能梯度层进行完全固化，对于该层功能梯度层进行预固化；
步骤6：打印后处理：
所有功能梯度层打印完成后，关闭防沉降供料模块Ⅰ、防沉降供料模块Ⅱ、约束牺牲层供料模块或FDM送丝模块；主动混合模块、被动混合打印喷头、约束牺牲层打印喷头或FDM打印喷头、UV固化单元返 回到初始工位；关闭打印平台加热功能；关闭正压气路、高压直流电源；
将打印的功能梯度制件从打印平台取下，放置到UV固化箱或者真空烘箱中进行后固化；去除约束牺牲层，得到功能梯度件成品。
作为进一步的实现方式，所述步骤2中，如果打印的约束层和支撑结构是微尺度，采用材料喷射打印模式；如果打印的结构是介观和宏观尺度，采用材料挤出打印模式。
所述步骤3中，如果打印的功能梯度层结构是微尺度，采用材料喷射打印模式；如果打印的结构是介观和宏观尺度，采用材料挤出打印模式。
作为进一步的实现方式，根据所选用的约束牺牲层材料的不同，使用不同的剥离和去除方法。如果是水溶性材料，首先进行手工剥离，然后放置到40-70℃的热水中完全去除。如果是HIPS等特殊材料，主要采用柠檬烯溶液进行溶解去除。如果是ABS、PLA等材料，主要采用手工剥离去除，可以辅助超声等其他处理方法，但是遵循不能破坏功能梯度件的原则。
对于打印的功能梯度层进行预固化，预固化的程度控制在完全固化的60-90％范围内，根据所打印功能梯度材料，选用具体优化的数值。
上述本发明的实施例的有益效果如下：
(1)本发明的一个或多个实施方式采用三级材料均匀混合的方法，解决材料团聚和混合不均匀的问题，实现两种以及多种材料高效混合均匀，连续梯度材料的打印。第一级混合，对于打印材料Ⅱ(第一打印原材料和第二打印原材料均匀混合后的复合材料)先进行充分的预混，利用表面改性(避免团聚，尤其是纳米尺度填料和高固含量填料，存在严重的团聚现象)、超声振动或者球磨等工艺实现填料与液态基体材料充分完全均匀混合。第二级混合，通过螺杆混合实现材料的第二级混合，使得打印材料Ⅰ与打印材料Ⅱ在可振动混料室中连续稳定的均匀混合。第三级混合，通过振动的方式实现对材料的第三级混合。最后送入被动混合喷头中实现连续稳定的打印。这样材料经过多级的混合后，确保到达喷嘴处的打印材料具有更好的连续功能梯度性能。
(2)本发明的一个或多个实施方式通过引入主动混合(螺杆挤出+超声振动)，解决高固含量、高粘度材料的功能梯度制造难题；同时主动混合可以有效的防止材料在打印过程中出现沉降的问题；充分利用并结合了主动混合模块和被动混合打印喷头的优势，实现了高固含量原材料以及高粘度原材料的连续功能梯度材料和复杂三维结构一体化制造；通过设置防沉降供料模块I、防沉降供料模块II等，解决打印材料尤其是含有微尺度填料和高固含量填料由于易于沉降，导致无法稳定打印，特别是对于尺寸比较大的制件，由于打印时间长，导致材料沉降严重，从而无法稳定的打印；利用倒置的主动混合模块以及其他策略，解决了多材料打印混合气泡去除的难题，提高了打印功能梯度零件的性能和精度。
(3)本发明的一个或多个实施方式引入约束牺牲层结构。不同于传统材料和工艺的打印，无论是单一材料还是复合材料，打印过程中，材料的组分和性能基本保持不变，优化出的打印工艺参数通常整个打印过程中都适用的。针对连续功能梯度材料/结构在打印过程中材料的成分/组分和物化性能等实时发生变化，带来严重的挑战性打印难题，提出引入约束牺牲层结构。其带来的优势和显著效果：
1)在约束牺牲层的辅助作用下，克服了因连续功能梯度材料/结构打印过程中材料成分/组分和物化性能等不断发生变化所导致打印稳定性和一致性差的问题，打印工艺参数具有非常宽的工艺窗口，能确保打印的精度、几何形状、表面质量、连续梯度性能；
2)利用约束牺牲层结构辅助成形任意复杂功能梯度三维结构。由于打印当前层固化不完全，如果没有约束牺牲层的辅助，难以实现几何形状的精准控制，尤其是解决了已成形层由于处于没有完全固化状态，难以保持打印的几何形状。还可以精准成形低粘度光敏树脂类材料；辅助成形内部复杂结构、悬垂结构、 薄壁结构、倒切结构等；
3)提高打印精度和一致性。优化出的工艺窗口在非常大的范围内均适用。利用约束牺牲层结构，能确保打印的功能梯度材料/结构的每层厚度是设定的厚度，无论对于打印的单个功能梯度制件其在低含量填料功能梯度区域，还是高含量填料功能梯度区域，利用约束牺牲层结构都能确保相同的厚度(或者设定的变厚度，或者自适应厚度)，尤其是对于同一个打印件不同区域、同一批次、以及不同批次，所打印的能梯度制件都具有很好的一致性。
(4)本发明的一个或多个实施方式引入两步固化的策略，并在约束牺牲层结构辅助下，能够有效的提高打印效率，改进功能梯度制件的层间结合强度和连续梯度性能。具体方法是：每层打印过程中，对于已打印层(成形结构层)采用不会完全固化(即预固化)；完成当前层打印后，再将预固化的打印层进行完全固化，当前层实现预固化。引入两步固化工艺后，能够实现精准的控制层间的结合强度和梯度性能。解决了现有技术层间结合强度差，连续梯度性能和精度差的问题。
附图说明
构成本发明的一部分的说明书附图用来提供对本发明的进一步理解，本发明的示意性实施例及其说明用于解释本发明，并不构成对本发明的不当限定。
图1是本发明根据一个或多个实施方式的约束牺牲层打印采用材料挤出或者喷射成形工艺的打印设备结构示意图；
图2是本发明根据一个或多个实施方式的约束牺牲层打印采用材料喷射成形的打印原理图；
图3是本发明根据一个或多个实施方式的约束牺牲层打印采用材料挤出或者喷射成形工艺，约束牺牲层打印喷头结构示意图；
图4是本发明根据一个或多个实施方式的被动混合打印喷头结构示意图；
图5是本发明根据一个或多个实施方式的主动混合模块结构示意图；
图6是本发明根据一个或多个实施方式的约束牺牲层打印采用传统FDM打印工艺的打印设备结构示意图；
图7是本发明根据一个或多个实施方式的约束牺牲层打印采用传统的FDM工艺的打印原理图；
图8是本发明根据一个或多个实施方式的约束牺牲层打印传统的FDM打印工艺，约束牺牲层打印喷头结构示意图；
图9是本发明根据一个或多个实施方式的约束牺牲层打印采用材料挤出或者喷射成形工艺流程图；
图10是本发明根据一个或多个实施方式的约束牺牲层打印采用传统的FDM打印工艺流程图；
其中，1.约束牺牲层供料模块、2.防沉降供料模块I、3.防沉降供料模块II、4.主动混合模块、5.气压调节阀表I、6.气压调节阀表II、7.Z轴运动模组、8.连接架Ⅶ、9.连接架I、10.连接架II、11.X轴运动模组、12.正压气路、13.高压直流电源、14.辅助观测相机模块、15.被动混合打印模块、16.底座、17.打印平台、18.约束牺牲层打印模块、19.UV固化模块、20.底板、21.支架I、22.Y轴运动模组、23.FDM送丝模块、24.FDM打印模块、25.支架II；
401.步进电机、402.进料口I、403.进料口II、404.出料口、405.振动混料室、406.主动搅拌螺杆、1401.辅助观测相机、1402.连接架Ⅵ、1501.被动混合打印喷头、150101.被动混合进料通口、150102.被动混合正压气口、150103.静态混合器、150104.被动混合打印喷嘴、1502.连接架III、1503.气缸模组I、1801.约束牺牲层打印喷头、180101.约束牺牲层进料通口、180102.约束牺牲层正压气口、180103.适配器、180104.环形加热器、180105.约束牺牲层储料桶、180106.约束牺牲层喷头加热块、180107.约束牺牲层打印喷嘴、1802.连接架IV、1803.气缸模组II、1901.UV固化单元、1902.连接架V、1903.气缸模组III、 2401.FDM打印喷头、240101.步进电机、240102.供丝通口、240103.丝材、240104.散热片、240105.散热风扇、240106.FDM喷头加热块、240107.FDM打印喷嘴、2402.连接架Ⅷ、2403.气缸模组IV。
具体实施方式
应该指出，以下详细说明都是例示性的，旨在对本申请提供进一步的说明。除非另有指明，本文使用的所有技术和科学术语具有与本申请所属技术领域的普通技术人员通常理解的相同含义。
需要注意的是，这里所使用的术语仅是为了描述具体实施方式，而非意图限制根据本申请的示例性实施方式。如在这里所使用的，除非上下文另外明确指出，否则单数形式也意图包括复数形式，此外，还应当理解的是，当在本说明书中使用术语“包含”和/或“包括”时，其指明存在特征、步骤、操作、器件、组件和/或它们的组合；
为了方便叙述，本申请中如果出现“上”、“下”、“左”、“右”字样，仅表示与附图本身的上、下、左、右方向一致，并不对结构起限定作用,仅仅是为了便于描述本发明和简化描述，而不是指示或暗示所指的设备或元件必须具有特定的方位，以特定的方位构造和操作，因此不能理解为对本申请的限制。此外，术语“第一”、“第二”仅用于描述目的，而不能理解为指示或暗示相对重要性。
术语解释部分:本申请中的术语“安装”、“相连”、“连接”、“固定”等术语应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或为一体；可以是直接连接，也可以是通过中间媒介间接相连，可以是两个元件内部连接，或者两个元件的相互作用关系，对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本发明的具体含义。
实施例一：
本实施例提供了一种功能梯度材料和三维结构一体化制造的3D打印设备，如图1所示，包括XYZ三轴模组、防沉降供料模块I2(高固含量材料长时间储存无沉降)、防沉降供料模块II3(高固含量材料长时间储存无沉降)、约束牺牲层供料模块1、主动混合模块4、正压气路12、高压直流电源13、辅助观测相机模块14、被动混合打印模块15、约束牺牲层打印模块18、UV固化模块19、底板20、打印平台17、底座16等；
其中，XYZ三轴模组包括X轴运动模组11、Y轴运动模组22、Z轴运动模组7，Y轴运动模组22通过支架I21固定在底板20上方，在本实施例中，Y轴运动模组22设置两个，两个Y轴运动模组22沿底板20长度方向间隔一定距离设置。Y轴运动模组22上方安装有支架II25，支架II25一侧安装X轴运动模组11；Z轴运动模组7通过连接架I9与X轴运动模组11连接。
进一步的，打印平台17通过底座16固定在底板20上，且打印平台17对应于打印模块下方。所述打印平台17具有调平功能和电加热功能，打印平台17设有的加热装置为电加热棒或电加热片，其加热温度范围为20-200℃。打印平台的平面度不低于±5μm，其调平方式可以通过现有技术实现，此处不再赘述。
在本实施例中，X轴运动模组11、Y轴运动模组22采用龙门式结构，X轴运动模组11、Y轴运动模组22的运动平台工作行程0-900mm，定位精度不低于±5μm，重复定位精度不低于±3mm，最大速度500mm/s。所述Z轴运动模组7工作行程0-300mm，定位精度不低于±3μm，重复定位精度不低于±1μm，最大速度300mm/s。
进一步的，所述Z轴运动模组7通过连接架Ⅶ8与连接架II10相连，连接架II10上依次安装UV固化模块19、约束牺牲层打印模块18、被动混合打印模块15、辅助观测相机模块14；被动混合打印模块15通过管路连接主动混合模块4和正压气路12，主动混合模块4与防沉降供料模块I2、防沉降供料模块II3相连；约束牺牲层打印模块18通过管路连接约束牺牲层供料模块1和正压气路12。被动混合打印模块15与正压气路12相连的管路安装气压调节阀表II6，约束牺牲层打印模块18与正压气路12相连的管路安装 气压调节阀表I5。
约束牺牲层打印模块18和被动混合打印模块15与高压直流电源13的正极相连，在本实施例中，高压直流电源13能够输出直流高压、输出交流高压和输出脉冲高压，且能够设置偏压，设置的偏压范围0-2kV连续可调，直流高压0-5kV，输出脉冲直流电压0-±4kV连续可调，输出脉冲频率0-3000Hz连续可调，交流高压0-±4kV。
如图2所示，所述UV固化模块19包括UV固化单元1901、连接架V1902、气缸模组III1903，UV固化单元1901通过连接架V1902连接气缸模组III1903，气缸模组III1903安装于连接架II10侧面一端。所述辅助观测相机模块14包括辅助观测相机1401、连接架Ⅵ1402，辅助观测相机1401通过连接架Ⅵ1402安装于连接架II10另一端。
进一步的，所述约束牺牲层打印模块18包括约束牺牲层打印喷头1801、连接架IV1802、气缸模组II1803，约束牺牲层打印喷头1801连接高压直流电源13的正极；约束牺牲层打印喷头1801通过连接架IV1802连接气缸模组II1803，气缸模组II1803能够带动约束牺牲层打印喷头1801上下移动。
更进一步的，如图3所示，约束牺牲层打印喷头1801用于打印约束牺牲层材料，包括约束牺牲层进料通口180101、约束牺牲层正压气口180102、适配器180103、环形加热器180104、约束牺牲层储料桶180105、约束牺牲层喷头加热块180106和约束牺牲层打印喷嘴180107，约束牺牲层储料桶180105末端通过约束牺牲层喷头加热块180106连接约束牺牲层打印喷嘴180107，约束牺牲层储料桶180105外侧安装环形加热器180104；约束牺牲层储料桶180105顶部安装适配器180103，且约束牺牲层储料桶180105顶端通过适配器180103连接约束牺牲层进料通口180101和约束牺牲层正压气口180102。
所述约束牺牲层正压气口180102通过软管与正压气路12相连，且此软管上安装气压调节阀表I5。约束牺牲层进料通口180101与约束牺牲层供料模块1相连接。仅仅通过正压控制单元挤出约束牺牲层材料定义为挤出打印模式，结合正压控制单元和高压直流电源13，约束牺牲层被喷射成形定义为喷射打印模式。
在本实施例中，约束牺牲层供料模块1采用精密注射泵，其中料筒可以进行加热，并通过可加热管道和转接头与约束牺牲层进料通口180101相连接。可以理解的，在其他实施例中，约束牺牲层供料模块1也可以采用微量注射泵、蠕动泵等。
约束牺牲层打印喷嘴180107采用武藏喷嘴，其通过导线与高压直流电源13的正极相连接。武藏喷嘴与放置在打印平台17上的基材形成强电场，驱动材料喷射沉积在基底上。
进一步的，被动混合打印模块15包括被动混合打印喷头1501、连接架III1502、气缸模组I1503，被动混合打印喷头1501通过连接架III1502连接气缸模组I1503，气缸模组I1503能够带动被动混合打印喷头1501上下移动。在本实施例中，所述气缸模组I1503、气缸模组II1803、气缸模组III1903可替换为电动位移台、直线定位平台和液压缸等。
如图4所示，被动混合打印喷头1501包括被动混合进料通口150101、被动混合正压气口150102、静态混合器150103、被动混合打印喷嘴150104，被动混合打印喷嘴150104安装于静态混合器150103一端，被动混合进料通口150101和被动混合正压气口150102安装于静态混合器150103另一端；所述被动混合进料通口150101通过软管连接主动混合模块4，被动混合正压气口150102通过软管连接正压气路12。
主动混合模块4混合后的材料进入静态混合器150103，静态混合器150103实现两个功能：其一，对于主动混合模块4输送的打印材料进一步均匀混合；其二，确保打印材料连续稳定提供给打印喷头，确保连续功能梯度材料/和结构打印的实现和稳定性。利用正压气路12实现打印材料从静态混合器150103稳定均匀的输送到打印喷嘴末端。
在本实施例中，所述被动混合打印喷头1501包括但不限定于金属喷嘴、塑料喷嘴、玻璃喷嘴、硅材料喷嘴等，喷嘴的内径尺寸0.5μm-1mm。所述被动混合打印喷头1501打印功能梯度材料采用挤出或者喷射成形工艺。所述正压气路12的工作范围0.1bar-1Mpa。
进一步的，如图5所示，所述主动混合模块4包括步进电机401、振动混料室405、主动搅拌螺杆406，主动搅拌螺杆406设于振动混料室405内部，二者的轴线重合；振动混料室405具有超声振动功能。所述主动搅拌螺杆406连接步进电机401，步进电机401固定于振动混料室405一端外侧；主动搅拌螺杆406在步进电机401驱动作用下旋转，能够将材料混合均匀并挤出振动混料室405。在本实施例中，主动搅拌螺杆406采用通常的搅拌螺杆结构。
振动混料室405另一端为出料口404，出料口404通过软管与被动混合打印喷头1501的被动混合进料通口150101相连。使用时，所述振动混料室405竖直设置，出料口404位于顶端，步进电机401位于底端。在本实施例中，出料口404呈锥台型结构。
所述振动混料室405侧面设置若干进料口，以接入两种或两种以上的材料。在本实施例中，振动混料室405的侧面设有进料口I402、进料口II403，进料口I402与防沉降供料模块I2相连，进料口II403与防沉降供料模块II3相连。
打印材料I从进料口I402进入振动混料室405，打印材料II从进料口II403进入振动混料室405，由步进电机401带动主动搅拌螺杆406旋转，以使材料在振动混料室405中进行混合，随着混合的进行将混合好的材料从储料口404送入连接软管，通过软管进入被动混合打印喷头1501。
进一步的，所述防沉降供料模块Ⅰ2、防沉降供料模块Ⅱ3可以是电动搅拌压力桶等，并通过软管和管接头等与振动混料室405的进料口相连接。所述防沉降供料模块Ⅰ2中用于放置打印材料I，打印材料I是第一打印原材料，其包括但不限定于以下材料：光敏树脂、PDMS、水凝胶、热固性环氧树脂等光固化或者热固化材料。
所述防沉降供料模块Ⅱ3中用于放置的打印材料II，打印材料II是第一打印原材料和第二打印原材料的均匀混合液体，第二打印原材料包括但不限定于以下材料：各种微纳米材料，诸如SiO 2、Al 2O 3、TiO 2、SiC、ZrO 2、石墨烯、碳纳米管等粉体或者颗粒材料。微纳米材料的尺寸30nm-50μm。
在本实施例中，约束牺牲层供料模块1中用于放置打印材料III，打印材料III是第三种打印原材料，第三种打印原材料包括但不限定于以下材料：优先选用各种水溶性的材料如PVA等。
综上所述，本实施例的技术方案为：
(1)采用三级材料均匀混合的方法，解决材料团聚和混合不均匀的问题，实现两种以及多种材料高效混合均匀，连续梯度材料的打印。第一级混合，对于打印材料Ⅱ(第一打印原材料和第二打印原材料均匀混合后的复合材料)先进行充分的预混，利用表面改性(避免团聚，尤其是纳米尺度填料和高固含量填料，存在严重的团聚现象)、超声振动或者球磨等工艺实现填料与液态基体材料充分完全均匀混合。
第二级混合通过螺杆混合实现材料的第二级混合，使得打印材料Ⅰ与打印材料Ⅱ在振动混料室405中连续稳定的均匀混合。第三级混合通过振动的方式实现对材料的第三级混合。最后送入被动混合喷头中实现连续稳定的打印。这样材料经过多级的混合后，确保到达喷嘴处的打印材料具有更好的连续功能梯度性能。
(2)通过引入主动混合(螺杆挤出+超声振动)，解决高固含量、高粘度材料的功能梯度制造难题；同时主动混合可以有效的防止材料在打印过程中出现沉降的问题。
(3)引入约束牺牲层结构。不同于传统材料和工艺的打印，无论是单一材料还是复合材料，打印过程中，材料的组分和性能基本保持不变，优化出的打印工艺参数通常整个打印过程中都适用的。针对连续 功能梯度材料/结构在打印过程中材料的成分/组分和物化性能等实时发生变化，带来严重的挑战性打印难题，提出引入约束牺牲层结构。其带来的优势和显著效果：
1)在约束牺牲层的辅助作用下，克服了因连续功能梯度材料/结构打印过程中材料成分/组分和物化性能等不断发生变化所导致打印稳定性和一致性差的问题，打印工艺参数具有非常宽的工艺窗口，能确保打印的精度、几何形状、表面质量、连续梯度性能；
2)利用约束牺牲层结构辅助成形任意复杂功能梯度三维结构。由于打印当前层固化不完全，如果没有约束牺牲层的辅助，难以实现几何形状的精准控制，尤其是解决了已成形层由于处于没有完全固化状态，难以保持打印的几何形状。还可以精准成形低粘度光敏树脂类材料；辅助成形内部复杂结构、悬垂结构、薄壁结构、倒切结构等；
3)提高打印精度和一致性。优化出的工艺窗口在非常大的范围内均适用。利用约束牺牲层结构，能确保打印的功能梯度材料/结构的每层厚度是设定的厚度，无论对于打印的单个功能梯度制件其在低含量填料功能梯度区域，还是高含量填料功能梯度区域，利用约束牺牲层结构都能确保相同的厚度(或者设定的变厚度，或者自适应厚度)，尤其是对于同一个打印件不同区域、同一批次、以及不同批次，所打印的能梯度制件都具有很好的一致性。
实施例二：
本实施例提供了一种功能梯度材料和三维结构一体化制造的3D打印方法，采用实施例一所述的3D打印设备，约束牺牲层打印采用材料喷射成形工艺，如图9所示，包括以下步骤：
(1)模型设置。确定打印零件的几何结构；
(2)模型信息处理。确定每层的几何信息(路径、层厚等)，生成打印数据文件；
(2)打印前处理，完成打印前的准备工作。确定材料的配比，分别对打印材料Ⅰ、打印材料Ⅱ进行预处理；设置打印的供料速度、打印速度、底板温度、喷头温度、气压、电压等；
(3)打印功能梯度结构，主要包括被动混合打印喷头1501与约束牺牲层打印喷头1801相互配合、按配比输送材料和喷射材料，先打印牺牲层，再打印功能梯度结构层，完成几何成形；
(4)每层打印完成后，Z轴升高一个层厚的高度，再完成下一层结构的打印。重复以上过程，直至完成所有层结构打印完成；
(5)打印后处理。关闭各个装置、模块，取下打印完成含有辅助支撑结构的成形功能梯度结构件，然后把辅助支撑结构与功能梯度样件进行分离(剥离、特殊溶液溶解或热水溶解等)。
所述打印功能梯度结构，根据实际打印的需要(打印效率和实际打印要求或者精度要求等)，可以设置多层具有相同的材料信息。
本实施例以光敏树脂RGD835/Al 2O 3功能梯度陶瓷绝缘子为施例，实现连续功能梯度材料和复杂三维结构一体化制造的工作方法，并说明具体工艺流程步骤：
步骤1：打印数据文件准备。根据打印件的结构要求，确定陶瓷绝缘子从一侧到另一侧Al 2O 3的浓度0％-50％呈连续变化，确定每层打印信息，约束牺牲层打印喷嘴180107采用武藏喷头，内径250μm，打印高度为0.1mm，线间距设为100μm；被动混合打印喷嘴150105采用金属不锈钢喷嘴，型号21G(外径为810μm，内径为510μm)，打印高度0.05mm，线间距300μm。
步骤2：打印前处理。
(2-1)约束牺牲层打印，约束牺牲层打印材料优选为具有水溶性的PVA，将其放入约束牺牲层供料模块1中，约束牺牲层供料模块1中的料筒可以进行加热，并通过可加热管道和转接头将打印材料输送到约束牺牲层储料桶180105，然后利用气路正压和高压直流电源13，喷嘴与放置在打印平台17上的基材形 成强电场，驱动打印材料从武藏喷嘴中喷射沉积出来。
(2-2)主被动混合打印，光敏树脂RGD835纯溶液为打印材料I；进行变组份打印液的配置，使用超声、球磨机制备Al 2O 3含量50％的光敏树脂RGD835/Al 2O 3混合液，使Al 2O 3颗粒均匀分散在光敏树脂RGD835溶液中，然后进行抽真空处理，制作成高浓度光敏树脂RGD835/Al 2O 3混合液为打印材料II。将打印材料I(纯光敏树脂RGD835)、打印材料II(Al 2O 3含量50％浓度光敏树脂RGD835/Al 2O 3混合液)分别放置到防沉降供料模块I2和防沉降供料模块II3中，然后利用主动搅拌螺杆406对打印材料I和打印材料II在振动混料室405进行均匀搅拌及振动后并送入静态混合器150103中，利用正压气路12、高压直流电源13将静态混合器150103中的材料稳定均匀的送到打印喷嘴，将混合均匀的打印材料从不锈钢喷嘴打印出来。
(2-3)把打印平台17加热温度设置到80℃，约束牺牲层供料模块1中的料筒、加热管道、约束牺牲层喷头加热块180106、环形加热器180104加热到200℃，UV固化模块19、辅助观测相机模块14和高压直流电源13处于待机状态，被动混合打印喷头、约束牺牲层打印喷头1801移动到打印工位IIA，并处于待机状态，各个运动平台处于使能状态，完成整个打印前的准备。
步骤3：连续功能梯度结构打印。
(3-1)送料，基于每层打印数据信息、程序信息，设置供料速度和供料时间，将约束牺牲层的打印材料PVA输送到约束牺牲层储料桶180105；根据各组分的材料要求和材料配比，准确的设置供料模块的供料速度和时间，向主动混合模块4输送需要的打印材料I和打印材料II(体积比或者重量比)，混合完成后送入被动混合打印喷头1501。
(3-2)打印约束牺牲层，利用约束牺牲层供料模块1将约束牺牲层打印材料PVA(打印材料III)输送到约束牺牲层储料桶180105，然后利用气缸模组II1803带动约束牺牲层打印喷头1801下降到打印工位IIB，用约束牺牲层打印气压调节阀表5精密调整气路压力(正压50kpa)，把打印材料输送到约束牺牲层储料桶180105，开启高压直流电源13，并把电压值调至1500V，使喷嘴与放置在打印平台17上的基材形成强电场，将打印材料从武藏喷嘴拉出来，按照程序设定的路径，打印构件的约束牺牲层；该约束牺牲层打印完成后，气缸模组II1803带动约束牺牲层打印喷头1801上升到初始印工位IIC(原位)。
(3-3)打印功能梯度层，利用防沉降供料模块I2和防沉降供料模块II3将打印材料I和打印材料II输送到主动混合模块4中，通过主动混合模块4混合后，材料通过主动混合模块出料口404软管送入静态混合器150103，然后用气压调节阀表II6精密调整气路压力(正压10kpa)，把打印材料输送到被动混合打印喷嘴150104，开启高压直流电源13，并把电压值调至800V，使喷嘴与放置在打印平台17上的基材形成强电场，将打印材料从不锈钢喷嘴拉出来，按照程序设定的路径，该功能梯度层材料打印在约束牺牲层内。功能梯度层打印完成后，气缸模组I1503带动被动混合打印喷头1501上升到初始印工位I C(原位)。
(3-4)根据打印需要，被动混合打印喷头1501与约束牺牲层打印喷头1801相互配合，按照打印程序设定的工艺参数、打印路径和打印顺序交替喷出打印材料，并根据几何信息，驱动XYZ三轴运动，先打印牺牲层，再打印功能梯度结构层，进行几何成形。
步骤4：约束牺牲层每打印完一层，Z轴上升0.1mm的高度；被动混合每打印完一层，Z轴上升0.05mm的高度，并且在打印完一层后，开启UV固化单元1901，控制UV固化单元1901移动到打印工位IIIA，气缸模组1903带动UV固化单元1901下降到打印工位IIIB，固化该层的混合液，固化20s，把该打印层的材料固化90％左右，预固化成形后，气缸模组1903带动UV固化单元1901上升到初始印工位III C(原位)。在混合液的第二层打印完成后，然后再用UV固化单元1901固化20s，把上一层的打印材料完全固化，该层的材料固化90％左右；随着层数的增高，改变防沉降供料模块I2和防沉降供料模块II3的供料速度，使Al 2O 3的浓度呈连续变化。
步骤5：重复以上操作，完成所有的打印。
步骤6：打印后处理。
(6-1)打印完成后，关闭约束牺牲层供料模块1、防沉降供料模块I2、防沉降供料模块II3，关闭材料约束牺牲层加热块180106、环形加热器180104和打印平台17的加热功能，关闭高压直流电源13，关闭UV固化单元1901，关闭主动混合模块4，把被动混合打印喷头1501、约束牺牲层打印喷头1801、UV固化单元1901返回工作台初始打印位置，
(6-2)将打印完成的含有PVA约束牺牲层的光敏树脂RGD835/Al 2O 3功能梯度陶瓷绝缘子零件从打印平台17上取下，放置到UV固化箱中进行后固化，实现更充分的固化，提高产品的良率。
(6-3)去除约束牺牲层。然把整个零件放在温水中，进行PVA约束牺牲层与功能梯度样件的分离，得到功能梯度件成品。对于水溶性材料，首先进行手工剥离，然后放置到40-70℃的热水中完全去除。如果是HIPS等特殊材料，主要采用柠檬烯溶液进行溶解去除。
本实施例引入两步固化的策略，并在约束牺牲层结构辅助下，能够有效的提高打印效率，改进功能梯度制件的层间结合强度和连续梯度性能。具体方法是：每层打印过程中，对于已打印层(成形结构层)采用不会完全固化(即预固化)；完成当前层打印后，再将预固化的打印层进行完全固化，当前层实现预固化。引入两步固化工艺后，能够实现精准的控制层间的结合强度和梯度性能。解决了现有技术层间结合强度差，连续梯度性能和精度差的问题。
实施例三：
本实施例提供了一种功能梯度材料和三维结构一体化制造的3D打印设备，如图6-图8所示，包括XYZ三轴模组、防沉降供料模块I2(高固含量材料长时间储存无沉降)、防沉降供料模块II3(高固含量材料长时间储存无沉降)、主动混合模块4、正压气路12、高压直流电源13、辅助观测相机模块14、被动混合打印模块15、FDM打印模块24、FDM送丝模块23、UV固化模块19、底板20、打印平台17、底座16等；
本实施例与实施例一的区别在于将实施例一中的约束牺牲层打印模块18替换为FDM打印模块24，FDM打印模块24连接FDM送丝模块23。FDM送丝模块23中放置打印材料III,打印材料III为FDM常用的材料ABS、PLA、TUP等。在本实施例中，FDM打印材料采用PLA。FDM送丝模块23将丝材(热塑性丝状材料)240103输送到FDM打印模块24中。
进一步的，如图7和图8所示，所述FDM打印模块24包括FDM打印喷头2401、连接架Ⅷ2402、气缸模组IV2403，所述FDM打印喷头2401通过连接架Ⅷ2402连接气缸模组IV2403，气缸模组IV2403安装于连接架II10侧面。
所述FDM打印喷头2401包括步进电机240101、供丝通口240102、散热片240104、散热风扇240105、FDM喷头加热块240106、FDM打印喷嘴240107，供丝通口240102用于丝材240103通过，步进电机240101用于为丝材240103提供输送动力。FDM喷头加热块240106安装于FDM打印喷嘴240107上方，用于熔化丝材240103。
步进电机240101将准备好的打印材料从FDM送丝模块23通过供丝通口240102输送入FDM送丝模块24的FDM打印喷嘴240107，在FDM喷头加热块240106的作用下，把打印材料熔化成半液态，熔化后的打印材料被挤压出来。由于FDM打印模块24连续打印，会长时间高温，所以需要散热片240104和散热风扇240105对步进电机240101和整个FDM打印模块24进行散热降温。
实施例四：
本实施例提供了一种功能梯度材料和三维结构一体化制造的3D打印方法，采用实施例三所述的3D 打印设备，约束牺牲层打印是采用传统的FDM打印工艺，如图10所示，包括以下步骤：
(1)模型设置。确定打印零件的几何结构；
(2)模型信息处理。确定每层的几何信息(路径、层厚等)，生成打印数据文件；
(2)打印前处理，完成打印前的准备工作。确定材料的配比，对打印材料Ⅰ、打印材料Ⅱ进行预处理；设置梯度材料打印的速度、温度、气压、电压等；设置FDM打印模块的供料速度(步进电机240101的转速)、打印速度、喷头温度等；
(3)打印功能梯度结构，主要包括被动混合打印喷头1501与FDM打印喷头2401相互配合、按配比输送材料和挤出，先打印牺牲层，再打印功能梯度结构层，完成几何成形；
(4)每层打印完成后，Z轴升高一个层厚的高度，再完成下一层结构的打印。重复以上过程，直至完成所有层结构打印完成；
(5)打印后处理。关闭各个装置、模块，取下打印完成含有辅助支撑结构的成形功能梯度结构件，然后把辅助支撑结构与功能梯度样件进行分离(剥离、特殊溶液溶解或热水溶解等)。
所述打印功能梯度结构，根据实际打印的需要(打印效率和实际打印要求或者精度要求等)，可以设置多层具有相同的材料信息。
本实施例以粒径1μm的BN/PDMS混合液与粒径20μm的BN/PDMS混合液功能梯度热界面为例，实现连续功能梯度材料和复杂三维结构一体化制造的工作方法，并说明具体工艺流程步骤：
步骤1：打印数据文件准备。根据打印件的结构要求，确定功能梯度热界面从一侧到另一侧的浓度变化为粒经1μm的BN含量40％的BN/PDMS混合液过渡到粒经20μm的BN含量40％的BN/PDMS混合液再过渡到粒经1μm的BN含量40％的BN/PDMS混合液的连续梯度变化，确定每层打印信息；FDM打印喷嘴240107，内径400μm，打印高度为0.2mm，线间距设为350μm；被动混合打印喷嘴150104采用金属不锈钢喷嘴，型号21G(外径为810μm，内径为510μm)，打印高度0.2mm，线间距300μm。
步骤2：打印预处理。
(2-1)FDM打印，FDM打印材料选为具有热塑性的PLA，将其放入FDM送丝模块23中，由供丝通口240102送至FDM打印喷头2401，在喷头加热块240106的作用下，把打印材料熔化成半液态，然后被挤压出来。
(2-2)主被动混合打印，将PDMS弹性体和固化剂按照20：1混合后，再使用超声波振动法制备粒经1μm的BN含量40％的BN/PDMS混合液，进行搅拌混合，使BN颗粒均匀分散在PDMS溶液中，然后进行抽真空处理，制作成粒经1μm的BN含量40％BN/PDMS混合液为打印材料I；进行另一组份打印液的配置，将PDMS弹性体和固化剂按照5：1混合后，再使用超声波振动法制备粒经20μm的BN含量40％的BN/PDMS混合液，进行搅拌混合，使BN颗粒均匀分散在PDMS溶液中，然后进行抽真空处理，制作成粒经20μm的BN含量40％BN/PDMS混合液为打印材料II。
将打印材料I(粒经1μm的BN含量40％的BN/PDMS混合液)、打印材料II(20μm的BN含量40％的BN/PDMS混合液)分别放置到防沉降供料模块I2和防沉降供料模块II3中，然后利用螺杆对打印材料I和打印材料II在振动混料室405进行均匀搅拌及振动后并送入静态混合器中，利用正压气路12、高压直流电源13将静态混合器中的材料稳定均匀的送到打印喷嘴，将混合均匀的打印材料从不锈钢喷嘴打印出来。
(2-3)把打印平台17加热温度设置到80℃，FDM喷头加热块240106加热到200℃，散热风扇240105、UV固化模块19、辅助观测相机模块14和高压直流电源13处于待机状态，被动混合打印喷头1501、FDM打印喷头2401移动到打印工位IIA，并处于待机状态，各个运动平台处于使能状态，完成整个打印前的准 备。
步骤3：连续功能梯度结构打印。
(3-1)送料，基于每层打印数据信息、程序信息，设置供丝速度(步进电机240101转速)和供丝时间，将FDM的打印丝材PLA由供丝通口送至FDM打印喷嘴；根据各组分的材料要求和材料配比，准确的设置供料模块的供料速度和时间，向主动混合打印模块4输送需要的打印材料I和打印材料II(体积比或者重量比)，混合完成后送入被动混合打印喷头。
(3-2)打印约束牺牲层，利用FDM送丝模块23将FDM打印丝材PLA通过供丝通口240102输送到FDM打印喷头2401，然后利用气缸模组IV2403带动FDM打印喷头2401下降到打印工位IIB，将打印丝材从FDM打印喷嘴240107挤压出来，按照程序设定的路径，打印构件的约束牺牲层；该约束牺牲层打印完成后，气缸模组IV2403带动FDM打印喷头2401上升到初始印工位IIC(原位)。
(3-3)打印功能梯度层，利用防沉降供料模块I2和防沉降供料模块II3将打印材料I和打印材料II输送到主动混合模块4中，经过混合将混均匀的材料送入被动混合打印模块15中，通过静态混合器150103，然后用气压调节阀表II6精密调整气路压力(正压30kpa)，把混合均匀的打印材料输送到被动混合打印喷嘴150104，开启高压直流电源13，并把电压值调至1200V，使喷嘴与放置在打印平台17上的基材形成强电场，将打印材料从不锈钢喷嘴拉出来，按照程序设定的路径，打印功能梯度构件。功能梯度层打印完成后，气缸模组I1503带动被动混合打印喷头1501上升到初始印工位I C(原位)。
(3-4)根据打印需要，被动混合打印喷头1501与FDM打印喷头2401相互配合，按照打印程序设定的工艺参数、打印路径和打印顺序交替喷出打印材料，并根据几何信息，驱动XYZ三轴运动，先打印牺牲层，再打印功能梯度结构层，进行几何成形。
步骤4：约束牺牲层每打印完一层，Z轴上升0.2mm的高度；被动混合每打印完一层，Z轴上升0.2mm的高度，并且在打印完一层后，利用打印平台17温度固化30s，把该打印层的材料固化80％左右，在混合液的第二层打印完成后，然后再利用打印平台17温度固化30s，把上一层的打印材料完全固化，该层的材料固化80％左右；在打印过程中，随着层数的增加，打印平台17温度也要适当增加，而且，在打印到合适的高度时候，开启上部的UV固化单元1901，对结构顶部进行固化。随着层数的增高，改变防沉降供料模块I2和防沉降供料模块II3的供料速度，使BN的浓度呈连续变化。
步骤5：重复以上操作，完成所有的打印。
步骤6：后处理。
(6-1)打印完成后，关闭步进电机240101、防沉降供料模块I2、防沉降供料模块II3、主动混合模块4，关闭FDM喷头加热块240106、打印平台17的加热功能，关闭高压直流电源13，关闭UV固化单元1901，把被动混合打印喷头1501、FDM打印喷头2401、UV固化单元1901返回工作台初始打印位置，
(6-2)将打印完成的含有PLA约束牺牲层的1μm颗粒BN/PDMS混合液与20μm颗粒BN/PDMS混合液功能梯度热界面零件从打印平台17上取下，放置到真空烘箱(120℃)中进行后固化，实现更充分的固化，提高产品的良率。
(6-3)去除约束牺牲层。主要采用手工剥离去除，进行PLA约束牺牲层与功能梯度样件的分离，得到功能梯度件成品。对于ABS、PLA等材料，主要采用手工剥离去除，可以辅助超声等其他处理方法，但是遵循不能破坏功能梯度件的原则。
以上所述仅为本申请的优选实施例而已，并不用于限制本申请，对于本领域的技术人员来说，本申请可以有各种更改和变化。凡在本申请的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本申请的保护范围之内。

Claims (10)

  1. 功能梯度材料和三维结构一体化制造的3D打印设备，其特征在于，包括主动混合模块、被动混合打印模块、约束牺牲层打印模块，所述主动混合模块的输入端与多个防沉降供料模块相连，用于实现主动混合多种材料均匀混合；主动混合模块的输出端与被动混合打印模块相连，用于将主动混合后的材料接入被动混合打印模块进行静态混合；
    所述被动混合打印模块、约束牺牲层打印模块安装于XYZ三轴模组一侧；所述约束牺牲层打印模块连接约束牺牲层供料模块，在约束牺牲层材料的辅助作用下能够打印形成复杂功能梯度三维结构；
    其中，主动混合模块包括振动混料室、安装于振动混料室的主动搅拌螺杆，振动混料室能够进行超声振动；进入主动混合模块的多种材料在超声振动及主动搅拌螺杆搅拌作用下均匀混合，并通过主动搅拌螺杆挤出；
    被动混合打印模块包括被动混合打印喷头、能够带动被动混合打印喷头上下移动的气缸模组I；约束牺牲层打印模块包括约束牺牲层打印喷头、能够带动约束牺牲层打印喷头上下移动的气缸模组II。
  2. 功能梯度材料和三维结构一体化制造的3D打印设备，其特征在于，包括主动混合模块、被动混合打印模块、FDM打印模块，所述主动混合模块的输入端与多个防沉降供料模块相连，用于实现主动混合多种材料均匀混合；主动混合模块的输出端与被动混合打印模块相连，用于将主动混合后的材料接入被动混合打印模块进行静态混合；
    所述被动混合打印模块、FDM打印模块安装于XYZ三轴模组一侧；所述FDM打印模块连接FDM送丝模块，FDM送丝模块能够将丝材输送到FDM打印模块中；
    其中，主动混合模块包括振动混料室、安装于振动混料室的主动搅拌螺杆，振动混料室能够进行超声振动；进入主动混合模块的多种材料在超声振动及主动搅拌螺杆搅拌作用下均匀混合，并通过主动搅拌螺杆挤出；
    被动混合打印模块包括被动混合打印喷头、能够带动被动混合打印喷头上下移动的气缸模组I；FDM打印模块包括FDM打印喷头、能够带动FDM打印喷头上下移动的气缸模组IV。
  3. 根据权利要求1或2所述的功能梯度材料和三维结构一体化制造的3D打印设备，其特征在于，所述主动搅拌螺杆连接步进电机，主动搅拌螺杆沿振动混料室内部轴向安装；所述振动混料室一端设有出料口，出料口与被动混合打印喷头相连；振动混料室侧面设有多个用于连接防沉降供料模块的进料口。
  4. 根据权利要求3所述的功能梯度材料和三维结构一体化制造的3D打印设备，其特征在于，所述振动混料室侧面设有进料口I、进料口II，进料口I与防沉降供料模块I相连，进料口II与防沉降供料模块II相连；
    防沉降供料模块I用于放置打印材料I，打印材料I为第一打印原材料，第一打印原材料采用光固化或者热固化材料；防沉降供料模块Ⅱ用于放置打印材料Ⅱ，打印材料Ⅱ为第一打印原材料和第二打印原材料的均匀混合液体；第二打印原材料采用微纳米材料。
  5. 根据权利要求1或2所述的功能梯度材料和三维结构一体化制造的3D打印设备，其特征在于，所述被动混合打印喷头包括静态混合器、被动混合打印喷嘴，被动混合打印喷嘴安装于静态混合器一端，静态混合器另一端连接被动混合进料通口和被动混合正压气口；
    所述被动混合进料通口通过软管连接主动混合模块，被动混合正压气口通过软管连接正压气路；被动混合打印喷嘴连接高压直流电源的正极。
  6. 根据权利要求1所述的功能梯度材料和三维结构一体化制造的3D打印设备，其特征在于，所述约束牺牲层打印喷头包括约束牺牲层储料桶，约束牺牲层储料桶一端安装约束牺牲层喷头加热块和约束牺牲 层打印喷嘴，约束牺牲层储料桶另一端安装适配器，且约束牺牲层储料桶通过适配器与约束牺牲层进料通口和约束牺牲层正压气口相连接；约束牺牲层打印喷嘴连接高压直流电源的正极。
  7. 根据权利要求1或2所述的功能梯度材料和三维结构一体化制造的3D打印设备，其特征在于，还包括安装于XYZ三轴模组的UV固化模块、辅助观测相机模块，所述UV固化模块包括UV固化单元、能够带动UV固化单元上下移动的气缸模组III。
  8. 根据权利要求1或2所述的功能梯度材料和三维结构一体化制造的3D打印设备，其特征在于，所述被动混合打印喷头下方设置用于放置基材的打印平台，所述打印平台通过底座安装于底板上方，打印平台安装有加热装置，且打印平台能够调平。
  9. 功能梯度材料和三维结构一体化制造的3D打印方法，其特征在于，采用如权利要求1或2所述的3D打印设备，包括：
    步骤1：打印处理：
    配制打印材料II，将第一打印原材料和第二打印原材料按照设计要求均匀混合；将打印材料Ⅰ放置到防沉降供料模块Ⅰ，打印材料II放置到防沉降供料模块Ⅱ，打印材料III放置到约束牺牲层供料模块或FDM送丝模块；
    将打印平台加热到设定温度，约束牺牲层打印喷头或FDM打印喷头、被动混合打印喷头移动到打印工位IIA，其他模块处于打印使能状态；
    步骤2：打印约束牺牲层：
    气缸模组II或气缸模组IV带动约束牺牲层打印喷头或FDM打印喷头下降到打印工位IIB，启动约束牺牲层供料模块或FDM送丝模块，使用约束牺牲层打印喷头或FDM打印喷头按照设定路径完成约束层和支撑结构的打印；
    步骤3：打印功能梯度层：
    被动混合打印喷头移动到打印工位IA，气缸模组II带动被动混合打印喷头下降到打印工位IB；按照设定梯度比例，防沉降供料模块Ⅰ和防沉降供料模块Ⅱ分别向主动混合模块中的振动混料室进行供料，经过主动混合内的主动搅拌螺杆搅拌与振动混合后经静态混合器进一步均匀混合；在正压控制单元挤出力的控制下，功能梯度材料被挤出到打印喷嘴出料口处，按照设定路径完成该功能梯度层打印；打印的该功能梯度层材料在约束牺牲层内；
    步骤4：功能梯度层固化：
    UV固化单元移动到打印工位IIIA，气缸模组III带动UV固化单元下降到打印工位IIIB；按照设定时间，通过UV光固化或者加热固化对于打印完成的功能梯度层进行预固化成形；功能梯度层预固化成形后，气缸模组III带动UV固化单元上升到初始印工位III C；
    步骤5：重复步骤2-4的操作，直到完成所有功能梯度层结构的打印；
    当完成该层功能梯度层打印后，进行固化处理，对于上一层预固化的功能梯度层进行完全固化，对于该层功能梯度层进行预固化；
    步骤6：打印后处理：
    所有功能梯度层打印完成后，关闭防沉降供料模块Ⅰ、防沉降供料模块Ⅱ、约束牺牲层供料模块或FDM送丝模块；主动混合模块、被动混合打印喷头、约束牺牲层打印喷头或FDM打印喷头、UV固化单元返回到初始工位；关闭打印平台加热功能；关闭正压气路、高压直流电源；
    将打印的功能梯度制件从打印平台取下，放置到UV固化箱或者真空烘箱中进行后固化；去除约束牺牲 层，得到功能梯度件成品。
  10. 根据权利要求9所述的功能梯度材料和三维结构一体化制造的3D打印方法，其特征在于，所述步骤2中，如果打印的约束层和支撑结构是微尺度，采用材料喷射打印模式；如果打印的结构是介观和宏观尺度，采用材料挤出打印模式；
    所述步骤3中，如果打印的功能梯度层结构是微尺度，采用材料喷射打印模式；如果打印的结构是介观和宏观尺度，采用材料挤出打印模式。
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CN109732905A (zh) * 2019-03-18 2019-05-10 青岛五维智造科技有限公司 功能梯度材料和成型结构一体化制造的3d打印机及工作方法
CN111284004A (zh) * 2020-02-19 2020-06-16 青岛理工大学 功能梯度材料与结构一体化制造的3d打印装置及打印方法
CN112895441A (zh) * 2021-01-18 2021-06-04 青岛理工大学 连续功能梯度材料和结构一体化制造的3d打印装置及方法

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CN116175963A (zh) * 2022-12-30 2023-05-30 福建工程学院 功能梯度结构的slm设备送料装置及其运行方法

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