Method and system for printing gradient material by depositing multiple powders on a roller base.

Abstract

To provide a method for making 3D components having graded material properties.SOLUTION: There are provided method and system of using a roller-based deposition process to place two or more powders at some level of precision to build a multi-material, functionally-graded component. Instead of formulating a liquid ink by dispersing powder feed stocks (metal or ceramic) in some binder-solvent mixtures, there is detailed the use of two different types of fluid deposited in a digital form on a roller surface. The two different types of fluids generate a "wetted pixel" that subsequently can capture a specific powder type with an affinity only to that fluid. Alternatives such as electrostatics, electrophotography, and the like are also provided to be used exclusively or with fluids to create an affine pixel to a particular powder type.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to the fabrication of multi-scale heterogeneous materials, and more specifically, to the fabrication of these materials by roller-based deposition of multiple powders.

Background Art

[0002] Additive manufacturing, also known as three-dimensional (3D) printing, enables the creation of three-dimensional objects by depositing a desired material or materials in successive layers. Prior to printing, the material is stored in one or more reservoirs of a 3D printer and extruded through one or more print heads that move within a predefined path and move to extrude the desired material at different points within the layer. When the stored material is extruded from one of the heads during separation, the extrusion is relatively straight, but the extrusion becomes more complex if a functionally graded material ("FGM") has to be created using 3D printing or similar fused deposition modeling ("FDM") printing. An FGM is a composite of two or more input materials whose concentration varies in different parts of the FGM, and those parts have properties that are a hybrid of the properties of the input materials and that depend on the relative amounts of the input materials within each part. Examples of the properties of a functionally graded material include organic structures such as muscle tissue that smoothly transitions into tendon to allow for a strong bond with strain relief when connecting to rigid bone. Similarly, in 3D printing, the ability to manufacture FGMs enables the creation of highly optimized part designs that meet bulk performance requirements such as weight, elasticity in a particular direction, and rigidity in other directions.

[0003] Creating a FGM requires mixing two or more input materials in a desired ratio within the 3D printer, and then extruding the mixture to the desired FGM proportions. Such mixing takes place in a chamber within the printer, where the input materials are supplied from a storage reservoir and the mixture is extruded through the print head. The composition of the mixture within the mixing chamber can only change at a specific rate, which is regulated by both the printer's characteristics and the initial composition of the mixture. The printer head is limited by this rate of change, which allows it to extrude a mixture of a particular composition. Therefore, if the predefined path of the extruder head requires the head to extrude a mixture of compositions that do not match the rate of change, the printer head may not be able to adapt to the extrusion command, and the FGM may not print properly without purging the contents of the mixing chamber. Such purging would not only significantly slow down the printing process but also waste material in the mixing chamber.

[0004] Existing technologies, which can be characterized as a combination of micromixing and extrusion molding, have several problems that need to be solved, such as the ability to handle high-viscosity inks, the ability to perform on-the-fly mixing in response to gradient changes, and the ability to handle completion speed. For these reasons, there is a need in the art to fabricate 3D parts with gradient material properties that have gradient resolution of particle size in one dimension (z) and gradient resolution of the linear order of particle size in the other two directions (x, y). [Overview of the project]

[0005] According to aspects of the embodiments, a method and system are provided that uses a roller-based deposition process for positioning two or more powders with several levels of precision to construct multi-material, functional gradient parts. Instead of formulating liquid inks by dispersing powder raw materials (metals or ceramics) in some binder-solvent mixture, the use of two different types of fluids deposited digitally on a roller surface is detailed. The two different types of fluids generate "wet pixels," which can then capture specific powder types that have affinity only for that fluid. Also provided are electrostatic, electrophotographic, and other methods to be used exclusively or in conjunction with fluids to generate affine pixels for specific powder types. [Brief explanation of the drawing]

[0006] Various exemplary embodiments of the disclosed apparatus, mechanisms, and methods are described in detail with reference to the following drawings, where similar reference numerals indicate similar or identical elements.

[0007] [Figure 1] This is a schematic diagram of a prior art system for modifying the composition of a material mixture that can be extruded onto the characteristics of a 3D printer.

[0008] [Figure 2] This is a schematic diagram of a system for the deposition of multiple powders on a roller base, useful for fabricating 3D parts, according to one embodiment.

[0009] [Figure 3] Figure 1 shows a roller and construction platform made of different materials according to one embodiment.

[0010] [Figure 4A] This shows a 2D representation of the roller surface after induction of two affine treatments. [Figure 4B] This shows a representation of particles having affinity for the applied treatment according to one embodiment.

[0011] [Figure 5A] This example demonstrates the introduction of a support material by inkjet deposition (5A) of a solidifying liquid wax according to one embodiment. [Figure 5B] This describes the introduction of a support material by doctoring (5B) of the support powder material according to one embodiment.

[0012] [Figure 6] One embodiment shows the xy arrangement of adhesive and the deposition of two materials for constructing a subsequent layer on top of a first layer using roller-based deposition.

[0013] [Figure 7] This flowchart shows the operation of a method for creating hierarchical gradient materials according to one embodiment.

[0014] [Figure 8] This flowchart shows how environmental factors can induce affinity of a powder type to specific pixels within a roller. [Modes for carrying out the invention]

[0015] Exemplary examples of the devices, systems, and methods disclosed herein are provided below. An embodiment of a device, system, or method may include any one or more, and any combination of, the embodiments described below. However, the present invention may be embodied in many different forms and should not be construed as being limited to the embodiments described below. Rather, these exemplary embodiments are provided to make this disclosure thorough and complete and fully convey the scope of the invention to those skilled in the art. Accordingly, the exemplary embodiments are intended to encompass all substitutes, modifications, and equivalents that may fall within the spirit and scope of the devices, mechanisms, and methods described herein.

[0016] In one aspect, a method of fabricating a hierarchical gradient material, comprising: treating a selected area of a roller surface to induce an affinity for a powder type for specific pixels on the roller surface; moving particles only to the treated selected areas of the roller surface, and then traversing the roller surface after treating across one or more powder beds such that the particles adhere to the selected areas of the roller surface, wherein the one or more powder beds have a powder feedstock having an affinity specific to the treated selected areas of the roller surface; depositing the powder on the roller surface onto a substrate to fabricate a gradient material layer by layer.

[0017] In another aspect, the method wherein the treatment of the selected area is selected from the group consisting of fluid, electrostatic, electrophotographic, or combinations thereof.

[0018] In another aspect, the method further comprising providing at least one reservoir for supplying fluid to a plurality of print heads.

[0019] In yet another aspect, the treating further comprises operating at least one of a plurality of print heads in communication with at least one reservoir to deposit at least one defined volume of at least one of the fluids onto the selected area of the roller surface.

[0020] In yet another aspect, the deposited fluid from at least one of the fluids imparts an affinity for a specific type of particles of one or more powder beds to the area of the roller surface.

[0021] In yet another aspect, the treatment of the selected area when using two or more powder beds is performed continuously or simultaneously.

[0022] In another aspect, the powder feedstock is selected from the group consisting of metals, ceramics, alloys, superalloys, refractory alloys, non-metals, polymers, composite materials, and mixtures thereof that enable deposition of the powder onto the substrate.

[0023] In another embodiment, the method further includes applying energy to a selected area of ​​the roller surface, thereby releasing powder particles onto the substrate.

[0024] In yet another embodiment, the coating of a support material is carried out layer by layer according to a pattern defined for supporting the gradient material during fabrication, wherein the layers of support material are coated following the formation of a corresponding powder layer on the substrate.

[0025] In another embodiment, the applied energy evaporates the fluid on a selected area of ​​the roller surface, thereby releasing the powder particles.

[0026] In a further embodiment, a system for manufacturing an object, comprising: a processing subsystem for processing selected areas of a roller surface to induce affinity of a powder type to specific pixels on the roller surface; and a processor coupled to a memory device having instructions for the processor to perform a method of manufacturing a hierarchical gradient material by running the roller surface after processing over one or more powder beds, where one or more powder beds have powder raw materials having an affinity specific to the processed selected areas of the roller surface, and depositing the powder on the roller surface onto a substrate to manufacture a gradient material layer by layer.

[0027] It is noted in advance that, in order to avoid unnecessarily obscuring the details of this disclosure, descriptions of well-known starting materials, processing techniques, components, equipment, and other well-known details may be simply summarized or omitted. Accordingly, where details are otherwise well-known, it is left to the application of this disclosure to propose or indicate options regarding those details. The drawings illustrate various embodiments of exemplary methods, apparatus, and systems for printing and using inline air bearing heaters after a surface coating has been applied to a recording medium.

[0028] Where any numerical range of a value is referred to herein, such a range is understood to include each and all numbers and / or fractions between the minimum and maximum values ​​of the range described. For example, the range 0.5–6% explicitly includes all intermediate values ​​such as 0.6%, 0.7%, and 0.9%, as well as 5.95%, 5.97%, and 5.99%, in addition to the endpoints 0.5% and 6%. Unless otherwise explicitly indicated in the context, this also applies to each other's numerical properties and / or element ranges described herein.

[0029] The modifier "approximately" used in relation to quantity includes the stated value and has a meaning determined by the context (for example, it includes at least the degree of error related to the measurement of a particular quantity). When used with a specific value, it should be considered that it discloses that value. For example, the term "approximately 2" also discloses the value "2", and the range "approximately 2 to approximately 4" also discloses the range "2 to 4".

[0030] As used herein, the term “affinity” refers to a liquid, charge, or electrophotographic pixel that specifically binds to a target particle or molecule(s) in a powder bed. It is well known in the art that affinity does not need to bind the target particle as a whole, but rather typically interacts with a defined portion of it.

[0031] A “hierarchical material” is a material having a structure spanning multiple orders of magnitude on a length scale. A “gradient material” is a material having a continuous and smooth spatial gradient in its composition. A “digital material” has a controlled spatial composition and form, i.e., the spatial composition consists of two planar 2D dimensions (XY) and Z dimensions that create 3D. The unit of a digital material is a voxel, which is a three-dimensional droplet or characteristic volume of material. A “multimaterial composite” is a material consisting of a suspension material, which may be a metal, ceramic, or polymer, also known as a matrix, and a dispersed reinforcing material, which may be a continuous or discontinuous phase, also known as a filler or reinforcing material. The reinforcing material may include macroscopic additives such as colloidal clay, carbon nanotubes, or carbon fibers or ceramic plates.

[0032] As used herein, the terms “printing device” or “printer” encompass any device that performs a print output function for the purpose of solid freeform fabrication (“SFF”), which includes a class of manufacturing methods that enable the direct fabrication of three-dimensional structures from computer-aided design (“CAD”) data. The SFF process is generally additive, in which the material is selectively deposited to build the product rather than being removed from a block or billet. Almost any product shape is achievable with SFF, no tools are required, mating parts and fully assembled mechanisms can be fabricated in a single process, multiple materials can be combined, and functional gradient material properties can be enabled. As used herein, printer includes 3D printers capable of fabricating 3D objects, such as functional gradient material (“FGM”) printers, fused deposition modeling (“FDM”) printers, and stereolithography (“SLA”) printers. Structures shown in figures may include additional features not shown for simplification, but it will be understood that the shown structures may be removed or modified.

[0033] The term “control device” is used herein to describe various devices relating to the operation of one or more devices that direct or regulate a process or machine. Control devices can be implemented in numerous ways (e.g., dedicated hardware) for performing the various functions considered herein. A “processor” is an example of a control device that employs one or more microprocessors that can be programmed using software (e.g., microcode) for performing the various functions considered herein. Control devices may be implemented with or without processors, or as a combination of dedicated hardware for performing some functions and processors (e.g., one or more programmed microprocessors and associated circuits) for performing other functions. Examples of control device components that may be used in various embodiments of this disclosure include, but are not limited to, conventional microprocessors, application-specific integrated circuits (ASICs), and field-programmable gate arrays (FPGAs).

[0034] The embodiments further include at least one machine-readable medium containing a plurality of instructions when executed on a computing device for carrying out or performing a method as disclosed herein. Such a computer-readable medium may be any available medium accessible by a general-purpose or dedicated computer. For example, but not limited to, such a computer-readable medium may include RAM, ROM, EEPROM, CD-ROM, or other optical disk storage devices, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to hold or store desired program code means in the form of computer-executable instructions or data structures. When information is transferred to or provided to a computer via a network or another communication connection (either wired, wireless, or a combination thereof), the computer appropriately checks the connection as a computer-readable medium. Thus, any such connection is appropriately referred to as a computer-readable medium. The above combinations should also be included within the scope of a computer-readable medium.

[0035] Computer executable instructions include, for example, instructions and data for invoking a general-purpose computer, a dedicated computer, or a dedicated processing device that performs a specific function or set of functions. Computer executable instructions also include program modules executed by a computer in a standalone or networked environment. Generally, program modules include routines, programs, objects, components, and data structures that perform a specific task or implement a specific abstract data type. In additive manufacturing, examples of these modules may include one or more roller modules for operating rollers in a desired order, fabrication modules for depositing material onto a substrate or build platform, applicator modules, actuator modules for depositing material onto a print head in a specific order, and energy applicator modules. Computer executable instructions, associated data structures, and program modules represent examples of program code means for performing steps of the methods disclosed herein. A particular sequence of such executable instructions or associated data structures represents an example of a corresponding action for performing the function described therein.

[0036] Embodiments of the present invention are not limited in this respect, but for example, considerations using terms such as “process,” “compute,” “calculate,” “determine,” “use,” “establish,” “analyze,” and “check” may refer to operations and / or processes of a computer, computing platform, computing system, or other electronic computing device that operate and / or convert data represented as physical (e.g., electronic) quantities in the computer’s registers and / or memory to other data similarly represented as physical quantities in the computer’s registers and / or memory, or to other information storage media capable of storing instructions to perform operations and / or processes.

[0037] The described embodiments of roller-based deposition are particularly useful for producing gradient materials for metal-ceramic, metal-metal, and ceramic-ceramic composites, which are typically produced in a non-digital, non-3D printing-based manner. Using the present invention, the fabricated 3D object has the desired geometric shape (an advantage of 3D printing) and is designed to conform to the intended geometric shape with digital gradients, i.e., pixel by pixel. In addition, roller-based deposition provides a resolution of material gradients down to the powder size scale in z, as well as several powder sizes (approximately 2-5x) in X and y.

[0038] In the descriptions of embodiments in this specification, parts that are the same as those in the previously described embodiments are indicated by the same reference numerals, and descriptions of parts that are the same as those in the previously described embodiments are omitted.

[0039] Figure 1 is a schematic diagram of a prior art system for modifying the composition of a material mixture that can be extruded on the characteristics of a 3D printer.

[0040] The illustrated prior art system 10 heavily relies on the rate of change of the composition of the material mixture that can be extruded on the characteristics of the 3D printer. Such dependence makes on-the-fly mixing difficult and makes it difficult to confirm reliable resolution. Two storage reservoirs 31 and 32 hold two different input materials, designated as material A and material B. Reservoirs 31 and 32 are connected to a mixing chamber 33 in which the input materials can be mixed and the output material can be mixed to be supplied to the print head 34 for extrusion printing of the part. Extrusion printing of parts has several problems, such as its inability to cope with high-viscosity inks that have significant pressure requirements for printing at small part resolutions (e.g., tracks with a diameter of 100 microns), the challenges of on-the-fly mixing where the mixer can easily change gradients within a range of a few voxels (i.e., switching from 100% A to 100% B), the inability to predictably determine the minimum achievable gradient resolution (i.e., ...49%, 50%, 51% vs. 49.5%, 50%, 50.5%) in a voxel context, and, most importantly, the inherent trade-off between print resolution and print speed, which is consistent with fused deposition modeling (FDM) printers. The upper limit of print speed is inherent in all serial, point deposition-based 3D printing processes. In addition, the minimum achievable volume can be large depending on the details of the extrusion machine system. In some auger-based displacement systems, this minimum comparable volume, corresponding to the floor voxel size for defining the gradient in the composition, can be anywhere in the range of 0.5 to 5 microliters, parallel to a cube with dimensions of 0.79 to 1.71 mm on each side. This is considerably larger compared to the powder size of 1 to 100 microns in diameter.

[0041] Figure 2 is a schematic diagram of a system for the deposition of multiple powders on a roller base, useful for fabricating 3D parts, according to one embodiment.

[0042] The illustrated system comprises a roller 330, a processing subsystem including an inkjet head 310 and a non-fluid exposure device 320, a control device 120, powder beds (340, 345), a raw material having affinity for specific pixels in the roller as induced by the processing subsystem, and a construction platform 360 such as a substrate for increasing fabrication layer by layer.

[0043] The inkjet head 310 can deposit multiple fluids (e.g., two or more) simultaneously without changing the fluid. A key advantage of inkjet for fluid deposition is its fine resolution (down to the scale of powder raw materials) or high-resolution material gradient, especially when working with functionally dependent materials manufactured in thin films. The very small volumes achievable with inkjet droplets (e.g., picoliters) are particularly well suited to this. Inkjet droplets of multiple fluids ejected in the same location react very rapidly, allowing for localized control of chemical reactions or physical interactions (e.g., wetting) within the deposited material, enabling very small-scale structuring of chemical activity, wetting, and other obtained material properties. The inkjet head 310 can distribute droplets of a defined volume of at least one of the fluids, ranging from 2 to 50 picoliters, or droplets onto a selected area of ​​the roller surface 330. High resolution and point-by-point deposition of materials enable the practical realization of structures (such as linear features that vary with length, or multi-material grids), allowing inkjet tools to produce products at a minimum level complementary to what can be achieved by stream-type deposition tools such as extrusion / syringe tools.

[0044] Returning to Figure 2, the embodiment illustrates the use of a roller-based deposition process for constructing multi-material, functional gradient components on a substrate such as the construction platform 360 by arranging two or more powders with several levels of precision. Instead of formulating liquid ink by dispersing powder raw materials (metal or ceramic) in several binder solvent mixtures used in printing systems such as those shown in Figure 1, the embodiment shown in Figure 2 illustrates the direct placement of powder onto a construction platform using rollers 330.

[0045] The idea is to use two different types of inductive affinity with a fluid by processing the roller, and then each “wetting pixel” captures a specific powder type that has affinity only to that fluid. To adhere the powder to the roller surface (330) with a selected component, embodiments inkjet (310) a defined volume of fluid onto the roller surface, or, in alternative use, use an exposure device 320 that causes temporary powder adhesion to the roller surface as the roller passes through the powder beds (340, 345) over (330p1, 330p2). In the release step, an energy device 363 is used to evaporate any liquid, thereby releasing the powder particles into the construction platform 360 or substrate. Powder already present in the construction platform 360 may or may not be wetted with the same liquid or a different liquid such as an adhesive, and then allow the movement of powder particles between the roller and the construction platform. To achieve a functional gradient using two or more different powders such as powder beds 340 and 345, the system can inkjet two or more different fluids whose affinity is intrinsic to the powder raw material. In the main embodiment, this may be one hydrophilic and one hydrophobic liquid, which may be designed to attract or adhere to base metal / ceramic particles (hydrophilic) or wax or polymer-coated metal / ceramic particles (hydrophobic). Such powder raw materials (340, 345) are available for use in conventional metal and ceramic manufacturing processes. For example, wax or polymer-coated metal particles are typically used in metal injection molding. The intended process then inkjet (310) the two fluids continuously or simultaneously onto a roller surface 330 (creating a pixel map of the intended multi-material or gradient structure within the layers), and then run the roll 330 sequentially through the two powder beds (340, 345) to adhere the two powder types to the roller. These powders are then, using instructions in the fabrication module, all moved to a construction platform 360 365 to fabricate parts layer by layer.Support materials can be introduced by either inkjet deposition of a solidifying liquid wax or by doctoring a support powder material as shown in Figures 5a-5B and 6. These support materials may be designed to burn off during post-printing sintering by melting at high temperatures or to be removed by de-powdering. With a powder (365) having an average diameter of 10 microns, the disclosed embodiments can obtain an xy arrangement resolution (rough surface area covered by inkjet droplets on several compatible substrates) of 20-50 microns and a z arrangement resolution of 10 microns (average diameter size). Both of these dimensions are at least an order of magnitude smaller than the dimensions of cubic voxels corresponding to the minimum compatible volume of some paste extrusion molding systems, which are in size from 0.79 to 1.71 mm.

[0046] The exemplary control system 120 may include one or more local processors 124 that individually operate the exemplary control system 120 and perform effect control and manipulation functions for additive manufacturing ("AM") 3D object formation, such as fabrication using gradient materials, specifically for implementing fluid, electrostatic, or electrophotographic pixel formation schemes. The processor(s) 124 may include at least one conventional processor or microprocessor that interprets and executes instructions that direct the control of specific functions of the exemplary control system 120 and the AM3D object formation process using the exemplary control system 120.

[0047] An exemplary control system 120 may include one or more data storage devices 122. Such data storage devices 122 may be used to store data or operating programs used by the exemplary control system 120, specifically by the processor(s) 122. The data storage devices 122 may, for example, be used to store information about one or more 3D object models for generating 3D objects in an AM 3D object forming device to which the exemplary control system 120 is associated. The stored 3D object model information may be transferred to data for printing a series of 2D slices (useful for creating pixel images on the surface of the roll 330) to form a 3D object in the manner generally described above with respect to the construction platform 360. The data storage devices 122 may also store updatable database information and may include, for example, random access memory (RAM) or another type of dynamic storage device for separately storing instructions for executing system operations by the processor(s) 124.

[0048] In the illustrated embodiment, the roll 330 rotates clockwise 335, starting with a clean surface. A fluid-type device 310 is disposed in a first location of the processing subsystem, which discharges a fluid with affinity for a particular powder type and forms an image thereon. The illustrated fluid-type device is one or more inkjet printheads that uniformly wet selected portions of the roll surface, such as pixels as shown in Figure 4A, so that one or more fluids form a layer with uniform and controlled thickness, adhering a particular powder to its surface at its selected location. In this way, the fluids can be paired by inkjeting two or more different fluids whose affinity is specific to the powder raw material. Sensors (not shown), such as an in-situ non-contact laser gloss sensor or a laser contrast sensor, can be used to verify the uniformity and position of the layer. Figure 3 shows an isometric view of a roller having different materials according to one embodiment.

[0049] For example, other forms of imaging and methods that induce a powder type affinity to specific pixels within a roller 330 without the use of fluid, such as electrostatic or electrophotographic methods. The same fluid-powder pair technique can be used for a fluid system of a first material and an electrophotographic or electrostatic system of a second material. A well-known exposure device 320 for creating a pixel image includes a raster output scanner (ROS) that illuminates a charged portion of the outer surface of the roll 330 to record a first electrostatic latent image, a light-emitting diode (LED) print head that emits an irradiated exposure light, or other electrostatic interactions with induced negative charges placed on the roll 330 via a mechanism that uses corona discharge to recharge to a relatively high, substantially uniform potential or similar mechanism.

[0050] Figure 3 shows a diagram of a roller having different materials according to one embodiment. In the illustrated embodiment, the roll 330 rotates counterclockwise in this depiction to place the first type of particles 410 and the second type of particles 420 onto a construction platform such as a substrate 360. As shown, the particles are diffused to any location on the surface of the roll 330 and can be gradually used to construct the fabricated part.

[0051] Figure 4A shows a 2D representation of the roller surface after induction of two affine treatments, and Figure 4B shows a representation of particles having affinity for the applied treatment according to one embodiment. Figure 4A is a 2D representation of a selected area of ​​the roll 330. The selected area details the use of two different types of fluids (or charged pixels) deposited digitally, continuously or simultaneously, on the 2D roller surface. The idea of ​​having two different types of fluids / charges is that each “wet pixel” or charged pixel then captures a specific powder type that has affinity only to that fluid or charged space. Figure 4A may have a first affine treatment (AT1) and a second affine treatment (AT2). This inductive affinity can be of a type selected from the group consisting of fluids, electrostatics, electrophotography, or combinations thereof. Generally, wet pixels are designed to attract or adhere to base metal / ceramic particles (hydrophilic) or wax or polymer-coated metal / ceramic particles (hydrophobic) in the powder bed. Figure 4B shows particles that are attractive to the applied inductive affinities AT1 and AT2. Roll 330 is labeled as 330B to indicate that powder particles (450) are attached to the surface of the roll, based on their respective affinities.

[0052] Figures 5A and 5B illustrate the introduction of a support material by either inkjet deposition of a solidifying liquid wax (5A) or doctoring of an exemplary support powder material (Figure 5B) according to one embodiment. The coated material is a separate sacrificial support material. The role of the support material in a 3D printer is to provide a platform for overhanging geometric shapes on subsequent layers during rising, layer-by-layer fabrication, and weakly solidifying materials that can be washed or dissolved are typically used as supports. Related techniques use wax as a support material, which hardens immediately after deposition and is melted in a post-processing purging step. As used herein, “support” refers to a material that can satisfy this structural requirement and at the same time be easily removed. Examples include polymer powders such as polyvinyl alcohol, polylactic acid, waxes having a defined melting temperature, free powder materials, salts, and other water-soluble or organic solvent-soluble powder raw materials. The support material can be introduced by inkjet deposition 312 of a liquid wax 505 that solidifies 510, or by doctoring 520 a support powder material 535 on a construction platform 360, substrate, or previously formed powder slice. When the support material is doctored 520, the support material consists of powder having an average particle size smaller than the average particle size of the main raw material in order to facilitate easy doctoring. For example, for a metal or ceramic powder with an average particle size of 10 microns, the doctored material may include wax or polymer particles having an average particle size of 1 to 3 microns. These support materials may be designed to burn off during post-printing sintering by melting at high temperatures or by de-powdering.

[0053] It should be understood that in some embodiments, planarization of the deposited layer may be performed before the deposition of another layer. The planarization process may be performed when a support material is used, or simply after the complete deposition of the layer, but before the deposition of the subsequent layer. Planarization establishes a flat surface on which subsequent layers are deposited, and is essential for removing raised irregular features that may result in leveling and other printing defects of the subsequent layer. These raised irregular features may result from the arrangement of the powder material, from the inherent size dispersion of the powder material (e.g., coarse particles or agglomerates), or from the introduction of a support material. Planarization may consist of running a heavy roller over the deposited surface to compact and flatten it, or running a sharp edge or doctoring blade along the surface at an intended height to remove raised, loose features in specific gaps. If the support material is wax or some other heated powder, planarization may be applied while the wax is sufficiently warm and molten, and the operation of either a roller or a doctor blade imposes liquid leveling of the molten material into a given gap.

[0054] Figure 6 shows a blanket deposition of adhesive material over the entire construction and selective xy arrangement of two materials using roller-based deposition on an existing layer including a support, according to one embodiment. In this embodiment, the system and method deposit adhesive 610 over the entire construction plate 360 ​​to facilitate the transfer process of a new powder layer 620 from roller 330 to an existing powder layer 602. A figure of the adhesive applicator 312 may be positioned to supply adhesive to the substrate 360 ​​(or over the layer 602 thereon) before the transfer process. Such adhesive 610 facilitates the transfer of layer 630 from roller 330 to the substrate 360 ​​or to an existing powder layer such as 602 on the construction platform. The adhesive 610 applied by the applicator 312 may be any commercially available adhesive product selected so as not to affect the support 510 or powder material 365, and can be applied by spraying, rolling, brushing, etc. The adhesive 610 itself may be a polymer material such as commercially available epoxy and other fast-curing materials, or it may be an inert liquid such as water, silicone, or mineral oil that has a general affinity for all different powder materials 365, and this affinity leads to the transfer of powder from the roller to the part. The adhesive 610 may be removed during post-printing sintering or during other finishing processes. Methods for removing the adhesive along with any support material used may include mechanical means such as heating in or inside a furnace or vibration, or chemical means such as a mineral oil or alcohol bath to selectively dissolve the adhesive and / or support.

[0055] A 3D printer using a printhead such as 312 can deposit solidified and non-solidified (e.g., adhesive) areas or areas(s) within the construction platform 360. A roller 330 can then deposit another layer of powder 620 onto the adhesive structure 610, as described with reference to Figure 2. The deposited adhesive structure 610 is shown sandwiched between the newly deposited material 630, with the previous layer 602 providing a bond between the layers.

[0056] During operation, the roller 330 fabricates a 3D object by depositing the supply material by moving the roller onto the substrate 360 ​​along a determined path. Typically, product fabrication is carried out by layer-by-layer deposition of the supply material. This planar layer deposition method for gradient material fabrication allows for the placement of multiple powders to create gradients in the material composition within the 3D object with finer resolution than currently enabled by methods relying on micromixing and extrusion (Figure 1). This roller-based technique should allow for particle placement with a resolution of particle diameter order in the z direction and linear coefficients of particle diameter in the x and y directions. An example relating to an average particle size of about 10 microns may correspond to a corresponding voxel dimension of about 10 microns (z) × 50 microns (y) × 50 microns (x). This corresponds to 25,000 cubic microns or 2.5 x 10 -5 This corresponds to a voxel volume of microliters. This is several orders of magnitude smaller than the achievable voxel size in some extrusion-based systems, which is about 0.5–5 microliters, which imposes different limits on the material gradients that can be fabricated without considering the minimum dead volume required for mixing.

[0057] Methods 700 and 720 detail a process for constructing a 3D object by digitally depositing multiple powder types onto a substrate such as a construction platform 360 using rollers. An inkjet head 310 and / or exposure device 320 exposes the rollers 330 to record images representing a pixel map of the intended multi-material or gradient structure. Some images have affinity with a particular type of construction material, and others have affinity with a different type of material, and so on. These images are then sequentially aligned with each other and transferred to the substrate-like construction platform 360 to form the gradient structure or 3D part.

[0058] Figure 7 is a flowchart illustrating the operation of Method 700 for manufacturing hierarchical gradient materials according to one embodiment. Method 700 begins with operation 710, which initiates an event such as system initialization or pressing a start button to manufacture / fabricate a part or object. For example, manufacturers of metal and ceramic parts for various applications such as aerospace, automotive, biomedical, energy, and other functional applications. Control is then passed to operation 720, in which Method 700 processes a selected area of ​​a roller surface, such as a roll 330, to induce an affinity of powder type to a particular pixel. Figure 4A is an example of a selected area adapted to different fluid types. Next, operation 740 is passed to operation 740, in which the roll 330 travels / rotates across a floor containing the raw material of material A. In operation 750, the roll 330 travels across a floor containing the stock of material B. In operations 740 and 750, a control device 120 using the roller module transmits a rotation signal or command to a mechanism such as an electric motor to rotate the roll 330. Similarly, the controller 120 using a program module can instruct another mechanism or a motor having cams and gears to position the roll 330 at a selected location such as the powder bed 340, 345 or the construction platform 360 to pick up the affine material and deliver / deposit the material attached to its surface.

[0059] After the roller has been run across the powder bed (340, 345), control is then passed to operation 760 for running the roll 330 across the construction bed 360 or substrate to deposit slices of the inclined material. This process is repeated until the material is produced layer by layer. In operation 780, the roller is cleaned using a well-known method such as IR lamp irradiation, chemical agents, solvents, shaking, or application of an electric field such as an electric field produced by a corona discharge device. Cleaning 780 may be performed between layers after the layer sequence or after all layers have been deposited by the roll 330. Note that operation 760 includes processes performed within the operation of the main roller for multiple powder volumes. Once the multi-material powder layers have been transferred to the construction, support, and adhesive materials described above, the deposition process described above (Figures 5, 6) may be performed before operations 710 and subsequent operations 720, etc., for depositing subsequent layers.

[0060] Figure 8 is a flowchart of method 720 for inducing affinity of a powder type to a specific pixel in a roller based on the environment. Method 720 begins with operation 722, in which affinity for the powder type is selected. As described above, affinity can take the form of fluid type or charged type, and the two types can be combined on the surface of the roll 330. When producing two distinct types of materials, such as two or more distinct fluid powder pairs, where each powder material has a wet affinity to one fluid and not to the other, or other means for inducing transient particle affinity to the roller surface—e.g., the use of electrophotography. Although described as applicable to two distinct materials, method 722 can extend from two fluid powder pairs to the use of a roller to construct a 3D object by digitally depositing multiple fluid powder pairs and multiple powder types onto a substrate.

[0061] In operation 724, the affinity of the fluid system is induced to these pixels within a selected area on the surface of the roll 330.

[0062] In operation 726, the method induces non-fluid affinity, such as static charge, within a selected area of ​​the surface of the roll 330.

[0063] In operation 728, fluid and non-fluid techniques are selected to induce affinity for each pixel. Then, in operation 724, operation 726, or operation 728, control is passed to operation 732 to attract the appropriate powder for the selected affinity.

[0064] It will be understood that some of the features and functions disclosed above, or their substitutes, may be desirablely combined with many other different systems or applications. Furthermore, various substitutes, modifications, variations, or improvements not currently anticipated or anticipated may subsequently be made by those skilled in the art.

Claims

1. A method for fabricating a multi-material 3D object, Processing a selected area of ​​a roller surface to impart affinity for a plurality of material powder types to specific pixels on the roller surface, wherein the processing includes adhering a first fluid to the roller surface and adhering a second fluid different from the first fluid to the roller surface, each of the first and second fluids being affinity types that impart affinity to each of the plurality of material powder types, and the plurality of material powder types including first material powder particles and second material powder particles, and processing After processing across one or more powder beds containing the plurality of material powder types, the first material powder particles are moved from one powder bed to only the processed selected area of ​​the roller surface having one of the first fluid and the second fluid on its surface, and the second material powder particles are further moved from another powder bed to only the processed selected area of ​​the roller surface having the other of the first fluid and the second fluid on its surface, thereby causing the roller surface to adhere to the selected area of ​​the roller surface. The first material powder particles and the second material powder particles each have an inherent affinity for the treated selected region of the roller surface having a corresponding one of the first and second fluids on its surface, and are to be driven. A method comprising simultaneously depositing first material powder particles and second material powder particles from the roller surface onto a substrate to produce the multi-material 3D object layer by layer.

2. The method according to claim 1, wherein running the roller surface over one or more powder beds containing the plurality of material powder types includes rolling with the roller having affinity type in direct contact with the first material powder particles and the second material powder particles when the powder particles are contained in the one or more powder beds.

3. The method described above is The method according to claim 1, further comprising coating a support material layer by layer according to a pattern defined for supporting the multi-material 3D object during manufacturing, wherein the layers of support material are coated following the formation of corresponding layers of the plurality of material powder types on the substrate.

4. The method described above is The method according to claim 1, further comprising supplying an adhesive to the substrate, wherein the adhesive facilitates the transfer of the plurality of material powder types from the roller surface to the substrate, or to existing layers of the plurality of material powder types on the substrate.

5. The method according to claim 2, wherein the processing uses the first fluid and the second fluid from at least one reservoir adapted to supply the fluid to a plurality of print heads.

6. The method according to claim 5, further comprising activating at least one of the plurality of printheads communicating with the at least one reservoir to deposit a defined volume of 2 to 50 picoliters of at least one of the first fluid and the second fluid on the selected area of ​​the roller surface.

7. The method according to claim 1, wherein running the roller surface after processing over one or more powder beds causes the plurality of material powder types to adhere to the selected area of ​​the roller surface during a single pass of the roller surface over the one or more powder beds.

8. The method according to claim 1, further comprising imparting simultaneous affinity of multiple material powder types to specific pixels on the roller surface by the above process.

9. The method according to claim 2, wherein the first material powder particles and the second material powder particles are selected from the group consisting of metals, ceramics, alloys, low-temperature alloys, high-temperature alloys, nonmetals, polymers, composite materials, and mixtures thereof, which enable the deposition of the powder onto the substrate.

10. The further includes supplying an adhesive to the substrate, wherein the adhesive facilitates the transfer of the plurality of material powder types on the roller surface to the substrate, or onto an existing layer of the plurality of material powder types on the substrate. The method according to claim 1, wherein the applied energy evaporates the fluid on the selected region of the roller surface, thereby releasing the first material powder particles and the second material powder particles.

11. The method according to claim 1, further comprising forming a patterned layer of a functionally graded material by the simultaneous deposition of the first material powder particles and the second material powder particles, wherein the patterned layer of the functionally graded material has a resolution of material gradient in terms of size of the first material powder particles and the second material powder particles.

12. The method according to claim 11, wherein the resolution of the material gradient is less than or equal to the average particle size of one of the first material powder particles and the second material powder particles, and the average particle size is within 10 to 1000 microns in x-y and 1 to 100 microns in z, leading to a voxel volume capable of corresponding to a composition of 5 to 100 picoliters.

13. The method described above is The method involves depositing support material layer by layer according to a defined pattern for supporting the functionally graded material during manufacturing, wherein the layers of support material are deposited after forming corresponding layers of the first material powder particles and the second material powder particles on the substrate. The method according to claim 12, further comprising planarizing the layer immediately after coating, wherein the layer may consist of a mixture of the deposited first material powder particles, the second material powder particles, and the support material.

14. A system for fabricating multi-material 3D objects, A processing subsystem for processing a selected area of ​​a roller surface to impart affinity to a plurality of material powder types for adhesion to specific pixels on the roller surface, wherein the processing includes adhering a first fluid to the roller surface and adhering a second fluid different from the first fluid to the roller surface, each of the first and second fluids being affinity types that impart affinity to each of the plurality of material powder types, the plurality of material powder types including first material powder particles and second material powder particles, One or more powder beds containing the plurality of material powder types, wherein each of the first material powder particles and the second material powder particles has an inherent affinity for the treated selected region of the roller surface having one of the first fluid and the second fluid on its surface, At least one processor configured to execute code, A roller module is configured such that, after processing over one or more powder beds, the roller surface is run to move the first material powder particles from one powder bed to only the processed selected area of ​​the roller surface having one of the first fluid and the second fluid on its surface, and further move the second material powder particles from another powder bed to only the processed selected area of ​​the roller surface having the other of the first fluid and the second fluid on its surface, thereby adhering the plurality of material powder types to the selected area of ​​the roller surface, A system comprising at least one processor, including a fabrication module configured to simultaneously deposit the first material powder particles and the second material powder particles onto a substrate from the roller surface to produce the multi-material 3D object layer by layer.

15. The system according to claim 14, wherein the roller module is further configured to roll with rollers having affinity type that directly contact the first material powder particles and the second material powder particles when the powder particles are contained in the one or more powder beds.

16. The system according to claim 14, wherein the processing subsystem further includes at least one reservoir that supplies fluid to a plurality of print heads.

17. The system according to claim 16, further comprising an actuator module configured to operate at least one of a plurality of printheads communicating with the at least one reservoir for depositing a defined volume of 2 to 50 picoliters of at least one of the first fluid and the second fluid on the selected area of ​​the roller surface.

18. The system according to claim 14, wherein the roller module is run over the roller surface after processing over one or more powder beds, so that the plurality of material powder types adhere to the selected area of ​​the roller surface in a single pass over the one or more powder beds.

19. The system according to claim 14, wherein the processing subsystem imparts simultaneous affinity of multiple material powder types to specific pixels on the roller surface.

20. The system according to claim 14, wherein the first material powder particles and the second material powder particles are selected from the group consisting of metals, ceramics, alloys, low-temperature alloys, high-temperature alloys, nonmetals, polymers, composite materials, and mixtures thereof, enabling the deposition of the powder onto the substrate.

21. The fabrication module is further configured to form a patterned layer of functionally graded material by the simultaneous deposition of the first material powder particles and the second material powder particles, and the patterned layer of functionally graded material has a resolution of material gradient in terms of the size of the first material powder particles and the second material powder particles. The aforementioned processor, An applicator module configured to deposit support material layer by layer according to a pattern defined to support the functional gradient material during fabrication, wherein the layers of support material are applied following the formation of corresponding layers of the first material powder particles and the second material powder particles on the substrate. The system according to claim 14, further comprising:

22. The applicator module is further configured to supply adhesive to the substrate, the adhesive facilitating the transfer of powder on the roller surface to the substrate or to existing layers of the plurality of material powder types on the substrate, The system according to claim 21, wherein the processor applies energy to the selected region of the roller surface to evaporate the fluid on the selected region of the roller surface, thereby releasing the first material powder particles and the second material powder particles.

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