DIMENSIONAL PRINTING

FIELD OF THE INVENTION

The present invention generally relates to the field of three-dimensional (3D) printing. The invention particularly relates to a system with a dynamic variable size nozzle orifice for three-dimensional printing of objects based on crafting and molding techniques and a method thereof. These variable size nozzle orifices are useful for printing of paste-based crafting media.

BACKGROUND OF THE INVENTION

Three-dimensional printers are used to build solid models by performing layer by layer printing of a building material. The building material can be of different forms, such as a liquid or a semiliquid at the three-dimensional printhead. For example, a solid material can be heated and then extruded from a three-dimensional printer nozzle. The layers of building materials can be solidified on a substrate. Three- dimensional printer systems can use a fused filament fabrication (FFF) process (sometimes called a fused deposition modeling (FDM) process) in which a filament is moved by a filament moving mechanism, toward a heated zone. The filament can be melted and extruded on a platform to form a three-dimensional object. However, the melted filament can adhere to the walls of the heated printhead, resulting in deformed printed lines. A commercially available FFF system uses a heated nozzle to extrude a melted material such as a plastic wire. The starting material is in the form of a filament which is being supplied from a spool. The filament is introduced into a flow passage of the nozzle and is driven to move like a piston inside this flow passage. The front end, near the nozzle tip, of this piston is heated to become melted. The rear end or solid portion of this piston pushes the melted portion forward to exit through the nozzle tip. The nozzle is translated under the control of a computer system in accordance with previously generated CAD data that has been sliced into constituent layers.

A number of different types of accessories for three-dimensional printing are described in the prior art. For example, the following patents are provided for their supportive teachings and are all incorporated by reference: Prior art document, US5121329 to S Scott Crump discloses an apparatus for making three-dimensional physical objects of a predetermined shape by sequentially depositing multiple layers of solidifying material on a base member in a desired pattern. The reference does not appear to disclose the formation of a mold (“mould”) or the use of any crafting medium.

Another prior art document, US20140291886 to Mark et al discloses three dimensional printers, and reinforced filaments, and their methods of use. In one embodiment, a void-free reinforced filament is fed into an extrusion nozzle. The reinforced filament includes a core, which may be continuous or semi-continuous, and a matrix material surrounding the core. The reinforced filament is heated to a temperature greater than the melting temperature of the matrix material and less than the melting temperature of the core prior to extruding the filament from the extrusion nozzle. The three-dimensional printer further includes a heating element which is used to heat the core and/or surrounding material.

Yet another prior art document, US20150314532 to Mark Gordon discloses manufacturing of inter-layer bonding in objects by three-dimensional printing techniques using one or more targeted heat sources (THSs) that preheat a targeted portion of an existing object material before additional material is added to the object. Three-dimensional printing is also improved, optimized or calibrated by pre- or post- heating of a targeted area. THS elements may be fixed, mobile, or a combination thereof to apply heat to targeted areas. In some embodiments a single print head may have multiple print nozzles. The print nozzle emits or deposits material fed through the print head. The print nozzle may be any suitable material, e.g., brass. The print nozzle may have one or more orifices to emit the printing material. However, this prior art document does not appear to discuss a dynamic variable nozzle orifice or the use of a crafting material paste.

Yet another prior art document, US20150174824 to Gifford discloses a modular three-dimensional printer system including a base subsystem and multiple exchangeable components. The base subsystem can have a three-dimensional motion module, a printhead module and a platform module. The multiple exchangeable components can include printheads having different configurations and functionalities, which can be exchangeably installed in the printhead module. In one of these embodiments, the system has a radiant heat source, which is located on a moving printhead to focus the heat in the area that is about to be fused. The heated substrate can increase the penetration of the bond between the substrate and the freshly deposited material. This document does not appear to discuss the use of a dynamic variable nozzle orifice for fabricating stronger bonds between the layers.

Yet another prior art document, US20160325498 to Daniel Gilbert discloses a three-dimensional printer based on a two-dimensional staggered nozzle array for depositing each layer in a raster scan mode. Each nozzle contains an individually controlled mechanical high-speed valve. Multiple nozzles are fed from a constant pressure reservoir, typically containing a molten polymer. However, this prior art document does not appear to discuss the use of a variable size or dynamic nozzle orifice for fabrication by layer-by-layer three-dimensional printing.

Yet another prior art document, US20080042321 to Russell et al. discloses an apparatus and methods for producing three-dimensional objects and auxiliary systems used in conjunction therewith. The apparatus and methods involve continuously printing radially about a circular and/or rotating build table using multiple printheads. The apparatus and methods also include optionally using multiple build tables. The auxiliary systems relate to build material supplies, printhead cleaning, diagnostics, and a monitoring operation of the apparatus. This prior art document discusses the concept of inducing a pressure differential for dispensing the binder through the nozzles. However, this prior art document fails to disclose varying the nozzle orifice size by changing the pressure flow.

Yet another prior art document, US8475946 to Dion et al. discloses a method of preparing a ceramic precursor article, a ceramic precursor made thereby, a method of making a ceramic article, and a ceramic article made by that method. It also includes a method of replicating a ceramic shape. This prior art document describes that one of the main challenges of the use of ceramic products with modern technologies is its reduction factor (shrinkage). Depending on the process used, e.g., such as drying, firing or hot pressing, a ceramic object can shrink by as much as 20 percent. Such shrinkage can be undesirable if the nature of the ceramic article requires precise dimensional control.

A non-patent literature prior art document, a Master degree thesis of Brady Godbey discloses surface finish control for three-dimensional printed metal tooling. The document reports that the tip orifice diameter of a nozzle may vary and will affect build speed and quality. Depending on the tip and build parameters, the minimum feature size ranges from 0.016 inches to 0.024 inches and the layer thickness may range from 0.005 inches to 0.013 inches. Despite its capability for small features, the manufacture of tall thin projections are not recommended as contact of the nozzle tip with the previously deposited layers may distort the part. However, this prior art document fails to provide a solution for depositing the layer without distortion using a single dynamic variable nozzle orifice.

Yet another prior art document, SE1500245 to Mats Moosberg discusses a three-dimensional imaging process for making objects, preferably metal objects or ceramic objects, on a layer-by-layer basis under the control of a data processing system. The process also includes the use of a filament material (in the form of a solid that melts to a fluid during the printing process) to build the mold and a crafting medium (in the form of a paste) for filling the hollow mold cavity. The method for building the three-dimensional model by extruding a crafting medium in parallel with a molding material as described in the prior art document, SE1500245, requires that it is sometimes necessary to fill thin whereas at other times it is necessary to fill out the large voids in layer-by-layer three-dimensional printing. Further, it also requires that the paste deposited on the layer is flat. For example, it requires filling very thin voids in a layer and to build thin walls, the paste extruder orifice needs to be small. However, a small orifice on the nozzle means that it can be difficult to fill large voids in an efficient way. Also, when the paste is extruded in a layer there is a need to make ensure that the paste in the layer is flat. This prior art document fails to provide the solution of the present invention for such cases.

However, the above mentioned references have one or more of the following shortcomings: (a) not discussing molding techniques; (b) not discussing the use of a building or crafting medium; (c) requiring multiple printheads with different size nozzles; (d) requiring nozzles with different size orifices; (e) the finishing of the final three-dimensional printed object is not of sufficient quality; and (f) none of the references discuss dynamic variable nozzle orifices comprising a soft flexible material.

It should be appreciated that during the three-dimensional layer-by-layer deposition of a crafting material paste, there can be two different problematic situations that can arise. In the first situation - where there are small voids requiring filling and the nozzle orifice is wider than the voids, the paste material being deposited can be spilled outside the voids. In the second situation - where there are large voids requiring filling and the nozzle orifice is small, then deposition will be ineffective because only a small amount of paste can be extruded through the small orifice. A solution to these two problematic situations is achieved by the dynamic variable nozzle orifice of the present invention. To construct a dynamic variable nozzle orifice, for example a soft flexible material, such as rubber, latex or silicone can be used. Such a dynamic variable nozzle would function such that when the extrusion pressure of the material being deposited is high the orifice will enlarge and allow for a wider extrusion flow and greater volume for filling, for example, large or wide voids. In another scenario, when the extrusion pressure is lower, the orifice will be narrower and provide a precise narrower extrusion to fill small voids. The hole size of the orifice can by this method is controlled by changing the pressure in the nozzle.

Another method of controlling the orifice size can be by a separate control mechanical function that is independent of the pressure at the nozzle. Such a method can be a iris type of device which can provide a range of orifice diameters at the nozzle tip. Both of these types of nozzles, i.e. the pressure-dependent variable dynamic nozzle and the independently controlled dynamic nozzle, and their delivery of crafting media, such as paste-based crating media, are embodiments of the present invention

By utilizing the function of a dynamic orifice size of the nozzle when depositing a crafting material inside a mold structure as described here, the printing time can be reduced without a reduction in resolution or detailing abilities.

The present application addresses the above-mentioned concerns and short comings with regard to providing an improved system for depositing a construction material for three-dimensional printing and filling variable size voids by using a dynamic variable nozzle orifice.

SUMMARY OF THE INVENTION

The present invention relates to three-dimensional printing and in particular to a system and method of printing with a dynamic variable size nozzle orifice for printing objects based on crafting and molding techniques, and a method thereof. In some embodiments the present invention provides a dynamic variable nozzle orifice which is made up of soft flexible material, wherein the diameter of the nozzle orifice is controlled by varying the pressure of the material being extruded through the nozzle. In other embodiments the present invention provides a nozzle orifice whose diameter is varied by a mechanical function that is separately controlled independently of the pressure of the material being extruded through the nozzle. The present invention relates to a system for three-dimensional printing of an object comprising a dynamic variable size nozzle orifice. In further embodiments the present invention relates to a system for printing of a three-dimensional object from a crafting medium.

In further embodiments the present invention relates to an orifice comprising a soft flexible material.

In further embodiments the present invention relates to an orifice comprising a soft flexible material selected from the group consisting of rubber, latex or silicone.

In further embodiments the present invention relates to an orifice for extruding a crafting medium at a pressure from about 200 kPa to about 10 MPa.

In further embodiments the present invention relates to an orifice having a variable diameter from about 0.05 mm to about 20 mm, and in other embodiments from about 0.2 mm to about 5 mm. It is contemplated that the diameter of the orifice can be varied depending upon the pressure at which the crafting medium is extruded and also upon the viscosity of the crafting medium. For example, at 500 kPa the orifice is 0.2 mm in diameter, at 2 MPa the orifice is 1 mm in diameter, at 3MPa the orifice is 2 mm in diameter, and at 5 MPa the orifice is 5 mm in diameter. In further embodiments the present invention relates to an orifice controlled by a mechanical function independent of the pressure at the nozzle.

In further embodiments the present invention relates to an orifice wherein the diameter of the orifice is controlled by an iris device.

In further embodiments the present invention relates to a system wherein the crafting medium comprises:

(i) from about 40% to about 80% by volume basis of a powder selected from metal powders, ceramic powders, and combinations, thereof; (ii) from about 0.5% to about 10% by volume of a binder; and

(iii) from about 15% to about 60% by volume of an aqueous solvent.

In further embodiments the present invention relates to a system wherein the crafting medium comprises:

(i) from about 40% to about 80% by volume basis of a powder selected from metal powders, ceramic powders, and combinations, thereof;

(ii) from about 0.5% to about 10% by volume of a binder; and

(iii) from about 15% to about 60% by volume of a non-aqueous solvent.

In further embodiments the present invention relates to a crafting medium wherein the metal or ceramic powder comprises particles having a size in the range from 0.1 - 100 micrometers. In further embodiments the present invention relates to a crafting medium wherein the metal powder is selected from silver, gold, copper, tin, nickel, chromium, zinc, tungsten, cobalt, aluminum, molybdenum, boron, iron, titanium, vanadium, niobium, silicon, manganese, steel, metal alloys, and combinations thereof. In further embodiments the present invention relates to a crafting medium wherein the ceramic powder is selected from silicon carbide, boron carbide, aluminum carbide, tungsten carbide, titanium carbide, tantalum carbide, silicon nitride, boron nitride, aluminum nitride, titanium nitride, zirconium nitride, steatite, forsterite, alumina, zircon beryllia, magnesia, mullite, cordierite, aluminum titanate, zirconia, and combinations thereof.

In further embodiments the present invention relates to a crafting medium wherein the binder is selected from organic binders, inorganic binders, and combinations thereof.

In further embodiments the present invention relates to a crafting medium wherein the in organic binder is selected from epoxy, polyurethane, agar-agar, starch, cellulosic materials, arrow root, Agar (E406), Alginic acid (E400), Sodium alginate (E401 ), Carrageenan (E407), Gum arabic (E414), Gum ghatti, Gum tragacanth (E413), Karaya gum (E416), Guar gum (E412), Locust bean gum (E410), Beta-glucan, Chicle gum, Dammar gum, Glucomannan (E425), Mastic gum, Psyllium seed husks, Spruce gum, Tara gum (E417), Gellan gum (E418), Xanthan gum (E415), polyethylene oxide , polycarboxylic acids (polyacrylic acid), polycarboxylates, polyvinyl alcohol, cellulose gum (Aquacel GSA and Aquacel GSH), hydroxymethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, and combinations thereof.

In further embodiments the present invention relates to a crafting medium wherein the inorganic binder is selected magnesium oxide, magnesic, cement, sorel cement, inorganic salts, and combinations thereof.

In further embodiments the present invention relates to a crafting medium wherein said aqueous solvent is selected from water, or water in combination with one or more non-aqueous solvents selected from the group consisting of methanol, ethanol, 1 -propanol, 2-propanol, acetone, acetaldehyde, ethyl acetate, C2-C4 diols, glycerol, acetonitrile, C4-alcohols, 2-ethoxyethanol, 2-ethyl hexanol, 1 ,2- dichloroethane, diisopropyl amine, isoamyl alcohol, propyl acetate, isopropyl acetate, and mixtures thereof. Also, contemplated are azeotropes.

In further embodiments the present invention relates to a crafting medium comprising a non-aqueous solvent instead of an aqueous solvent, such nonaqueous solvents selected from the group consisting of methanol, ethanol, 1 -propanol, 2- propanol, acetone, acetaldehyde, ethyl acetate, C2-C4 diols, glycerol, acetonitrile, C4- alcohols, 2-ethoxyethanol, 2-ethyl hexanol, 1 ,2-dichloroethane, diisopropyl amine, isoamyl alcohol, propyl acetate, isopropyl acetate, and mixtures thereof.

In further embodiments the present invention relates to a method of three- dimensional printing an object using the system of the present invention.

In further embodiments the present invention relates to a three-dimensional object printed using the system of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and objects other than those set forth above will become apparent when consideration is achieved to the following detailed description thereof. Such description makes reference to the annexed drawings wherein: FIG.1 depicts a schematic representation of the system in accordance with the present invention.

FIG. 2A depicts exploded views of the dynamic flexible nozzle orifice of the system, at high pressure, in accordance with the present invention.

FIG. 2B depicts exploded views of the dynamic flexible nozzle orifice of the system, at low pressure, in accordance with the present invention.

FIG. 3A depicts the extrusion of a crafting paste into a wide void defined by a molding layer, with a dynamic variable flexible nozzle orifice.

FIG. 3B depicts the extrusion of a crafting paste into a narrow void defined by a molding layer, with a dynamic variable flexible nozzle orifice. FIG. 4 illustrates a flow chart for an example of a method for generating a mold and then printing a three-dimensional object in accordance with the present invention.

FIG. 5 shows a soft flexible variable dynamic nozzle with the nozzle in a non- expanded mode defining a small orifice. FIG. 6 shows a soft flexible variable dynamic nozzle with the nozzle in an expanded mode defining a large orifice.

FIG. 7 shows a variable dynamic nozzle with a mechanical iris type device to control the orifice diameter. A separate control mechanism for the iris device is not shown.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention can be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that the embodiments can be combined, or that other embodiments can be utilized and that structural and logical changes can be made without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense.

Many Rapid Prototype processes have been developed in recent years and many more are currently being researched, but until recently, few of them have been used to fabricate paste or clay-based objects. Methods of three-dimensional printing using clay or ceramic materials and preparing molds are also known in the prior art documents. With three-dimensional printing techniques for fabricating objects on a layer-by-layer basis, it is very important to have good integration or inter-layer bonding within the objects. Due to undesired void formation, the inter-layer bonding might not be as strong as required and the resultant three-dimensional object quality can be compromised. Furthermore, different size voids can also form during or after the printing process. Flowever, filling these voids with crafting paste material using a single size orifice can be problematic. Either one has to use multiple printheads with multiple nozzles having different nozzle orifice diameters for the same material or one has to switch nozzles. During the three-dimensional layer-by-layer printing by depositing crafting material pastes, there can be two different situations: (i) First situation - when there are small voids required to be filled out and the nozzle orifice is wider than the voids, then the crafting paste material can spill or flow outside the voids; (ii) n the second situation - if there are large voids needed to be filled out and the nozzle orifice is small, then deposition of the crafting paste can be ineffective and only a small amount of paste can be extruded through the small orifice, which can be time-consuming. The present invention provides a solution in certain embodiments to solve the problem of filling different size voids and building strong inter-layer bonding by using a single, dynamic flexible nozzle orifice. The dynamic flexible nozzle orifice of the present invention is made up of a soft flexible material, so the orifice diameter can be varied by changing the extrusion pressure. In other embodiments, the present invention provides a solution by providing a dynamic nozzle orifice that is controlled by an external means. An example of such a dynamic nozzle orifice is an iris type of orifice.

FIG.1 depicts a schematic representation of a system for filling variable size voids by using a dynamic variable nozzle orifice which is made up of soft flexible material according to one of the embodiments of the present invention. The system 100 for drying a paste based crafting model during three-dimensional printing comprises: (a) supply arrangement for a filament material 101 for forming a mold layer for the object; (b) an extruder 103; (c) a feeding channel 106; (d) a plurality of nozzles 107 and 113; (e) a plurality of heating elements/systems 108 for melting the filament and 119 for drying the crafting medium; (f) a plurality of discharge orifices 109 and 114; (g) a supply arrangement for a crafting medium 110; (h) an actuator 112 for controlling the flow of the crafting medium; (i) a mold 116 (formed from the layer-by-layer deposition of the filament material); and (j) a platform 115 on which the system of the three-dimensional printer is fixed. The system has dual printhead which comprise a first dispensing nozzle 107 for depositing the filament 102 in flowable fluid form by the discharge orifice 109 to supply a filament 102 or a first material layer and a second dispensing nozzle 113 for depositing a crafting medium 111 or the second material layer which is in a paste form by the discharge dynamic variable nozzle orifice 114. The dynamic variable nozzle orifice 114 can be made up of a soft material, such as rubber, latex or silicone. In other embodiments the dynamic variable nozzle orifice can comprise an orifice that is controlled by an external device and is an iris-type shutter orifice. The system further comprises a holding element 118 which holds a dual printhead and a heating element/system 119.

A filament feeding device comprising a stepper motor (not shown) and idler and driving rollers 104 and 105 located opposite to drive rollers which work together to grip the filament there between and to advance it through a filament feeding channel 106 thereby regulating the flow of filament through the feeding channel. The extruder 103 can be of any different type such as roller, gear system, etc. The heating system 121 can consist of a radiating heater, and possibly an air circulation fan. The heating system may also have connectors 120, which can be of electric wire or pipes/tubes for blowing air. The heating system can also provide cooling or can reduce the temperature and can function as a temperature control system. Further, the temperature control system can include without limitation one or more of a heater, coolant, a fan, a blower, or the like.

As shown in the FIG. 1 , a system 100 in accordance with a preferred embodiment of the present invention comprises a supply 101 of filament material such as acrylonitrile butadiene- styrene (ABS) or Polylactic acid (PLA); a filament feeding device comprising a stepper motor (not shown), idler rollers 104 located opposite to drive rollers 105 which work together to grip the filament there between and to advance it through a filament feeding channel 106 thereby regulating the flow of filament through the feeding channel 106. The feeding channel 106 is made of a material having low thermal conductivity, such as for example Teflon. The system further includes a first dispensing nozzle 107, preferably made of a material with a thermal conductivity greater than 25 W/(m K), such as for example brass or similar metallic alloys. The first dispensing nozzle 107 can be heated to a temperature sufficiently high for the filament 102 to liquify. Heating elements 108, in the form of a resistance heating tape or sleeve, and a temperature sensor (not shown) are arranged around a lower portion of the nozzle 107 to regulate the temperature of the nozzle 107 to a temperature of approximatively 200°C to 240°C to convert a leading portion of the filament 102 into a flowable fluid state. The solid (un-melted) portion of the filament 102 inside the feeding channel 106 acts like a piston to drive the melted liquid for dispensing through a first discharge orifice 109. The drive motor (not shown) can be controlled to regulate the advancing rate of the filament 102 in the feeding channel 106 so that the volumetric dispensing rate of the fluid can be closely controlled. The filament material is preferably a thermoplastic polymer that softens and liquifies for easy deposition and which rapidly cools and hardens to provide a suitable mold. Thermoplastic polymers useful for forming the mold from the filament material can include the following: poly(propylene), poly(styrene), poly(lactic acid) (PLA), acrylonitrilebutadiene- styrene (ABS), polycarbonate abs (PC-ABS), nylon, poly(carbonate), poly(phenyl sulfone), ultem, poly(ethylene), acrylic [poly(methyl methacrylate)], poly(benzimidazole), poly(ether sulfone), poly(etherether ketone), poly(etherimide), poly(phenylene oxide), poly(phenylene sulfide), poly(vinyl chloride), poly(vinyldiene fluoride), poly(acetal), poly(vinyl acetate), poly(vinyl butyrate), poly(vinyl alcohol), poly(4-hydroxystyrene), poly(vinyl formate), poly(vinyl stearate), poly(acrylamide), poly(caprolactone), chitosan and combinations thereof.

As shown in the Figure 1 , the apparatus further includes a supply 110 of a crafting medium 111 , such as for example a metal clay or a ceramic clay. In a preferred embodiment of the invention, the crafting medium 111 comprises microscopic metal particles of metal, such as silver, gold, copper or alloys or combinations thereof, mixed with an organic binder and water. The supply 110 is preferably shaped as a conventional clay extruder comprising a cylindrical cavity and valve means 112 to control and regulate the flow of crafting medium toward a second dispensing nozzle 113 and through a second discharge orifice 114.

Both nozzles 107 and 113 are arranged at a predetermined distance from an object supporting platform 115. The dual printhead and the platform 115 are moved relative to one another in a movement pattern corresponding to a predetermined object 117. The fused filament is deposited through the first discharge orifice 109 while the dual printhead is moving in an X-Y-plane relative to the platform 115, to build one layer of a mold 116. Thereafter, the crafting medium 111 is deposited while the dual printhead is moving in an X-Y-plane relative to the platform 115 in order to fill the layer of the mold 116.

The crafting medium 111 is in the paste form. The layer of the crafting medium is required to be dried immediately, or a short time interval after printing, but in any event prior to the printing of the next crafting medium layer. The system 100 includes the heating system or drying apparatus 119 which can be connected on the printhead. The heating system is used for drying a paste of the crafting medium 111. This drying is accomplished by moving print head and it is possible after finishing each layer of the object (both mold and paste), to have the print head repeatedly scan the printed layer and apply heat and air circulation to improve drying in a controlled way. The drying apparatus can comprise a radiating heater, and possibly an air circulation fan. This can enable better evenness in the drying and reduce risks for cracks and also reduces problems in the next steps. Thereafter the dual printhead and the platform 115 are displaced in the Z- direction from one another by a distance corresponding to the thickness of a single layer so that the next layer can be deposited. The first and second dispensing nozzles 107 and 113 are used to deposit the melted filament and the crafting medium respectively and to alternate the deposition on a layer by layer basis, in such a manner that the mold is alternately built and then filled with crafting medium for each layer. When the deposition is achieved, the object 117 is embedded inside the mold 116. The mold 116 will thereafter be removed in order to release the object 117. That removal step is preferably achieved by heating the mold 116 to a temperature of approximately 200°C until the mold building material is melted away from the object 117. If the object 117 is made of metal clay, the metal contained in the object 117 is thereafter sintered to obtain a pure metal object.

In an alternate embodiment of the present invention, the apparatus further includes a heating means (not shown) for heating and melting the mold 116. Such heating means can consist of an insulated chamber, or an oven, inside which the mold 116 is exposed to heat energy to release the object 117.

A first supply of filament material used to build the mold. The supply of filament can comprise a rotatable spool on which the filament is wound. Such a filament material can be comprised of, but is not limited to, one or more of the following materials including various waxes, thermoplastic polymers, thermoset polymers, and combinations thereof. However, the primary modeling material preferably comprises an organic polymer with a reasonably low softening or melting point, e.g., acrylonitrile-butadiene-styrene (ABS) or Polylactic acid (PLA). As described above, thermoplastic polymers useful for forming the mold from the filament material can include the following: poly(propylene), poly(styrene), poly(lactic acid) (PLA), acrylonitrilebutadiene- styrene (ABS), polycarbonate abs (PC-ABS), nylon, poly(carbonate), poly(phenyl sulfone), ultem, poly(ethylene), acrylic [poly(methyl methacrylate)], poly(benzimidazole), poly(ether sulfone), poly(etherether ketone), poly(etherimide), poly(phenylene oxide), poly(phenylene sulfide), poly(vinyl chloride), poly(vinyldiene fluoride), poly(acetal), poly(vinyl acetate), poly(vinyl butyrate), poly(vinyl alcohol), poly(4-hydroxystyrene), poly(vinyl formate), poly(vinyl stearate), poly(acrylamide), poly(caprolactone), chitosan and combinations thereof. A second supply of crafting medium can be in paste form. Such a medium can comprise silicone, a ceramic material or the like. The crafting medium is preferably a commercially available metal clay usually comprising very small particles of metal such as silver, gold, bronze, or copper mixed with an organic binder and water commonly used in making jewelry, beads and small sculptures. FIG. 2A depicts exploded views of the dynamic flexible nozzle orifice of the system, at high pressure, in accordance with the present invention. FIG. 2B depicts exploded views of the dynamic flexible nozzle orifice of the system, at low pressure, in accordance with the present invention. The dynamic flexible nozzle orifice 14 for the second print head is made up of soft material. When the extrusion pressure is high (201A) to deposit the crafting paste material, the dynamic flexible nozzle orifice 14 is compressed and it widens the orifice 202A. Further, when the extrusion pressure is low (201 B) to deposit the crafting paste material, the dynamic flexible nozzle orifice 114 is not compressed, then the orifice diameter is narrower 202B.

The present invention how it works while filling out the crafting paste materials at different sizes of the voids during mold extrusion step is also clearly depicted in the FIG. 3A and FIG. 3B. FIG. 3A depicts mold extrusion step (302) at higher pressure 301A for filling or depositing wide void 303A with paste by widening a dynamic flexible nozzle orifice. FIG. 3B depicts mold extrusion step 302 at lower pressure 301 B for filling or depositing narrow void 303B with paste by narrowing a dynamic flexible nozzle orifice. The wide void is needed to be filled during mold extrusion step, the extrusion pressure is increases, and it compresses the dynamic flexible nozzle orifice. The more paste material is extruded from the nozzle orifice by widening the diameter of the orifice (FIG. 3A). The nozzle and the dynamic flexible nozzle orifice have geometry to smoothen the paste extrusion 304. During the deposition of the crafting material, it is require controlling the top surface of the extruded paste a flattening geometry, this flattening geometry will control the height of the extruded paste and make sure it completely fills the void. In other situation, when the small voids are require filling out during the mold extrusion step, the extrusion pressure is lowered, and it would not have effect on the dynamic flexible nozzle orifice. The only required paste material will be extruded from the nozzle orifice by narrow diameter of the orifice (FIG. 3B). FIG. 4 illustrates by a flow chart an example of a method for generating mold and then printing a three-dimensional object in accordance with the present invention. The method starts with providing three-dimensional model to the computer or any digital media, at block 401. Then digitally generating mold at block 402. At block 403, combining digitally generated mold and three-dimensional model. This step is one of the important steps of the present invention, it compares the three dimensional parameters of the digitally generated mold and three-dimensional model.

Then the system generates the detailed tool paths and extrusion instructions at block 404. The system also calculates and generates instructions for giving the correct paste extruder pressure in combination with a wanted extrusion width. The system also finalizes the thickness of the mold required and it selects the as thin as possible. The thickness of the mold surface, i.e. the mold skin thickness can be about 0.1 to about 10 mm. Further, the holes are made up of having a diameter from about 0.1 to about 0.4 mm. The holes should be evenly distributed over the mold surface. Then the instructions are sending to the printer or a system (as explained above and depicted in Fig. 1 ). Then the apparatus/printer starts printing of the combined mold and three-dimensional model layer by layer, at block 406. At block 407, extruding and depositing a mold material (filament material) with structural additive and crafting material in a layer by layer form. In block 407, there are several sub-steps involved (which are not depicted in the Fig. 3): such as providing a supply of mold building material in filament form; feeding the filament to enter one end of a flow passage of the first dispensing nozzle having a first discharge orifice on another end; heating the first dispensing nozzle to convert a leading portion of the filament therein to a flowable fluid; and dispensing the flowable fluid through the first discharge orifice to an object-supporting platform. Further, in block 407, there are several sub-steps involved: such as providing a supply of crafting medium in paste form; feeding the crafting medium to enter one end of a flow passage of the second dispensing nozzle having a second discharge orifice on another end; and during the dispensing step, operating the second dispensing nozzle for extruding the crafting medium on a layer.

Next at block 408, thereafter the dual printhead and the platform are displaced in the Z-direction from one another by a distance corresponding to the thickness of a single layer so that the next layer can be deposited. Next at block 409, if the printing of the all layers, meaning that the crafted object and mold is complete then it moves to the next step, block 410. Otherwise, the process starts repeats from block 407 until the entire object is completed.

At block 410, processing step involves the removing of the mold material. The mold material can be removed by for example burning or melting or by chemical, and all of these processes are easier if thinner layer. The next processing step is to remove the binder material at block 411. At block 412, the crafting material is transformed to the final finished product. Further, in an alternate example, the molding material can also include the structural additive such as metal, charcoal particles, ceramic, or other particles. The material of the mold material with structural additive is such that it prevents the fusing of the object (crafting layer) with the support structure material. In another scenario, the material of the structural additive also prevents fusing between one part of the object with another part of the object to create gap or space between them.

The present invention relates to a three-dimensional imaging process for making objects, preferably metal objects or ceramic objects, on a layer-by-layer basis under the control of a data processing system. Some of the process steps which are not included above in detail are: (a) providing a dual printhead including a first dispensing nozzle and a second dispensing nozzle; (b) during the dispensing step, moving the dual printhead and the object-supporting platform relative to one another in a plane defined by first and second directions and in a third direction orthogonal to said plane to form the flowable fluid into a three-dimensional hollow pattern having a molding cavity shaped in accordance with a predetermined three dimensional object; (c) by layer basis through the second discharge orifice onto the three-dimensional hollow pattern in order to gradually fill the molding cavity, thereby forming the predetermined three-dimensional object; and (d) removing the three- dimensional hollow pattern in order to release the predetermined three-dimensional object.

Crafting Medium

Although a wide variety of crafting media can be used with the methods and systems of the present invention, a particularly useful crafting medium contains a very low concentration of the binder organic base materials, such as starches, cellulose, cellulose derivatives, agar, etc., and around 15 to 60 volume% water. The binding organic base material content can be varied from 1 to 10 volume%. The binder can act as glue between the powder particles, and also as filler between the particles. The method of preparation of the three-dimensional object also includes the step of drying on a layer-by-layer basis. The drying is a continuous process in the present invention and can remove most of the water and/or other solvents or carriers from the binder composite material from each layer after depositing.

An exemplary crafting material useful herein comprises: (i) from about 40% to about 80% by volume basis of a powder selected from metal powders, ceramic powders, and combinations, thereof;

(ii) from about 0.5% to about 10% by volume of a binder; and

(iii) from about 15% to about 60% by volume of an aqueous solvent.

An exemplary crafting material useful herein comprises:

(i) from about 40% to about 80% by volume basis of a powder selected from metal powders, ceramic powders, and combinations, thereof;

(ii) from about 0.5% to about 10% by volume of a binder; and

(iii) from about 15% to about 60% by volume of a non-aqueous solvent.

Another crafting material useful herein comprises,

(i) from about 60% to about 70% by volume basis of a powder;

(ii) from about 1 % to about 5% by volume of a binder; and

(iii) from about 25% to about 35% by volume of an aqueous solvent.

Another crafting material useful herein comprises,

(i) from about 60% to about 70% by volume basis of a powder;

(ii) from about 1 % to about 5% by volume of a binder; and

(iii) from about 25% to about 35% by volume of a non-aqueous solvent.

The solvent or carrier for the crafting material can be an aqueous solvent. Such an aqueous solvent can be solely or primarily water, or can comprise other solvent materials which are generally water miscible. In other embodiments, a nonaqueous solvent or mixtures of non-aqueous solvents can be employed. Such non-aqueous solvents can be selected from the group consisting of methanol, ethanol, 1 -propanol, 2-propanol, acetone, acetaldehyde, ethyl acetate, C2-C4 diols, glycerol, acetonitrile, C4-alcohols, 2-ethoxyethanol, 2-ethyl hexanol, 1 ,2- dichloroethane, diisopropyl amine, isoamyl alcohol, propyl acetate, isopropyl acetate, and mixtures thereof. Also, contemplated are azeotropes.

In further embodiments the present invention relates to a crafting medium comprising a non-aqueous solvent instead of an aqueous solvent, such nonaqueous solvents selected from the group consisting of methanol, ethanol, 1 -propanol, 2- propanol, acetone, acetaldehyde, ethyl acetate, C2-C4 diols, glycerol, acetonitrile, C4- alcohols, 2-ethoxyethanol, 2-ethyl hexanol, 1 ,2-dichloroethane, diisopropyl amine, isoamyl alcohol, propyl acetate, isopropyl acetate, and mixtures thereof. Several materials can be used as the leaving component, i.e. the solvent or carrier, in the deposition technique involving continuous, layer-by-layer drying. One example of a departing component is water, with a vapor pressure of about 2.4 kPa. Higher vapor pressures, i.e. low boiling points, are in general preferred, as they will require less energy to drive away from the deposited part. However, including materials with vapor pressures which are very high as compared to water (acetaldehyde, for example) can in some instances cause difficulties with layer-to- layer and strand-to-strand bonding if the leaving component departs prior to the formation of a significant bond. In this case controlled drying, achieved via depression of the print temperature, can be employed during formation of the object. After formation of the object, the temperature (or other thermodynamic variable) can be changed to complete the removal of the leaving component.

Solvents used can be aqueous (e.g., water, and water with salts or surfactants), organic and primarily carbon based solvents, and organic solvents with halogen groups, fluorinated organic solvents, or mixtures of any of those aforementioned items. Mixtures of components may be chosen such that when the components leave the part, the components leave in a proportion identical or substantially similar to the proportion of the components in the deposited material.

In addition to the list provided below, materials such as dichloroethane, diiodoethane, fluorinated or chlorinated refrigerants, or degreaser materials as manufactured by DuPont (Operteron) or MicroCare (Tergo) can be used. Further, solvent drying specialty fluids added to liquids such as water or ethanol (and their mixtures), can be used. Such a solvent drying specialty fluid iis Vertrel XP10 Solvent Drying Specialty fluid by MicroCare.

In the three-dimensional printing process, it is necessary to use binders to provide rigidity to the crafting medium of the object during fabrication. Different types of binding materials can be used in these three-dimensional printing processes. Organic binders, such as epoxy, polyurethane, agar-agar, starch, cellulosic materials, Agar (E406), Alginic acid (E400), Sodium alginate (E401 ), Carrageenan (E407), Gum arabic (E414), Gum ghatti, Gum tragacanth (E413), Karaya gum

(E416), Guar gum (E412), Locust bean gum (E410), Beta-glucan, Chicle gum, Dammar gum, Glucomannan (E425), Mastic gum, Psyllium seed husks, Spruce gum, Tara gum (E417), Gellan gum (E418), Xanthan gum (E415), polyethylene oxide , polycarboxylic acids (polyacrylic acid), polycarboxylates, polyvinyl alcohol, cellulose gum (Aquacel GSA and Aquacel GSH), hydroxymethyl cellulose, hydroxypropyl cellulose, Carboxymethyl cellulose, etc. can be used while Inorganic binders, such as magnesium oxides, magnesic, cement, sorel cement, salts, etc. are used.

The three-dimensional objects with a powder plus binder constitution for sintering can pose several problems. The binder can be difficult to remove because it needs to be dissolved or burned out after the object is finished. The binder can also be hazardous and or can require toxic substances to dissolve it away. While removing the binder there is a risk for developing cracks and deformities in the resulting object. Furthermore, methods of three-dimensional printing using clay or ceramic materials and preparing a mold are also well known in the prior art documents. Most of these prior art documents discusses the drying or heating of the mold or clay paste post processing. A major problem is cracking of the deposited object when the drying is carried out at the end of the full deposition processing. Cracks and unevenness can develop on the mold or on the object. The present invention is providing solution to solve these problems of cracks and unevenness of the object or the mold.

A solution to this cracking problem is achieved in the present patent application. This solution is achieved by providing a crafting medium comprising a metal or ceramic, binder organic base materials, and water. The crafting medium which is in the paste form includes 40 volume% - 80 volume% metal/ceramic powder, 1 volume% - 10 volume% organic base material, and 15 volume% - 60 volume% water. The metal or ceramic powder particle size is in the range from 0.1 - 100 micrometers. In another embodiment of the invention, the crafting medium comprises microscopic particles of a metal, such as silver, gold, copper, tin, nickel, chromium, zinc, tungsten, cobalt, aluminum, molybdenum, boron, iron, titanium, vanadium, niobium, silicon, manganese, steel or alloys or combinations thereof, and also oxides of these metals, mixed with the binder, organic base material, and water. Also, additional corrosion inhibitors or sintering aiding or lubrication additives, generally in the range of 0.1 - 2 volume%, can be added.

In another embodiment, the powder is instead a ceramic powder such as silicon carbide, boron carbide, aluminum carbide, tungsten carbide, titanium carbide, tantalum carbide, silicon nitride, boron nitride, aluminum nitride, titanium nitride, zirconium nitride, steatite, forsterite, alumina, zircon beryllia, magnesia, mullite, cordierite, aluminum titanate and zirconia mixed with the binder organic base material and water. Also additional corrosion inhibitors, sintering aiding or lubrication additives, generally in the range of 0.1 - 2 volume%, can be added.

In both these immediately foregoing embodiments, the binder organic base material can be polyurethane, agar-agar, starch, cellulosic materials, Agar (E406), Alginic acid (E400), Sodium alginate (E401 ), Carrageenan (E407), Gum arabic (E414), Gum ghatti, Gum tragacanth (E413), Karaya gum (E416), Guar gum (E412), Locust bean gum (E410), Beta-glucan, Chicle gum, Dammar gum, Glucomannan (E425), Mastic gum, Psyllium seed husks, Spruce gum, Tara gum (E417), Gellan gum (E418), Xanthan gum (E415), polyethylene oxide , polycarboxylic acids (polyacrylic acid), polycarboxylates, polyvinyl alcohol, cellulose gum (Aquacel GSA and Aquacel GSH), hydroxymethyl cellulose, hydroxypropyl cellulose, Carboxymethyl cellulose, or combinations thereof.

Sintering aids such as salts, gum rosin or pine rosin, isopropyl alcohol, propylene glycol, copper oxides, other metal oxides, low melting point metals or alkaline earth metals can be used. Lubricants aids such as essential oils, glycerin, zinc stearate or other stearates, carbon black, silica and ferrous oxide can be used. Corrosion inhibitors such as those selected from the group consisting of nitrates of lithium, sodium, potassium, calcium, magnesium, zinc, cobalt, iron, chromium, and copper, and the nitrite of lithium, sodium, potassium, calcium, magnesium, zinc, can be used.

With the compositions and processes of the present invention, substantially all of the moisture, i.e. the water, and other solvent or carrier components for the binder of the crafting medium is removed immediately after deposition of each layer by use of the drying means or apparatus. By“substantially all of the moisture” is meant that at least about 90% by weight, and in further embodiments at least about 95% by weight, and yet in further embodiments at least about 99% by weight of the water and other solvent or carrier components are removed. This novel method of three-dimensional object building does not require the use of a post-processing debinding step. Furthermore, the present invention also provides a system for improved drying in a controlled manner of a paste based crafting model during three- dimensional printing and methods thereof. The drying means or apparatus can take the forms described above. These means make drying possible after printing each layer of the object (both mold and paste).

EXAMPLES

It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-discussed embodiments may be used in combination with each other. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description.

The benefits and advantages which may be provided by the present invention have been described above with regard to specific embodiments. These benefits and advantages, and any elements or limitations that may cause them to occur or to become more pronounced are not to be construed as critical, required, or essential features of any or all of the embodiments.

While the present invention has been described with reference to particular embodiments, it should be understood that the embodiments are illustrative and that the scope of the invention is not limited to these embodiments. Many variations, modifications, additions and improvements to the embodiments described above are possible. It is contemplated that these variations, modifications, additions and improvements fall within the scope of the invention.

EXAMPLES

The following examples further described and demonstrate embodiments within the scope of the present invention. The Examples are given solely for purpose of illustration and are not to be construed as limitations of the present invention, as many variations thereof are possible without departing from the spirit and scope of the invention. Example 1 : Crafting Medium and Process for Making

A crafting medium comprising the following components was prepared. The components are each on a volume % basis. Stainless steel powder 17-4: 62%

Distilled water : 32%

Arrow root powder: 4%

Xanthan gum 1 %

Polycarboxylate 1 %

A premix of the water and arrow root powder is prepared by heated to 80 °C with stirring. The premix is then cooled to room temperature. A separate premix of xanthan gum and the polycarboxylate is made by combining them with stirring to form a thick paste. Next, the stainless steel powder and the xanthan gum premix are added to the arrow root premix and combined using a mechanical stirrer.

The resulting paste is useful for three-dimensional printing. The paste can be printed on a line-by-line and layer-by-layer basis in conjunction with a mold layer. Each deposited paste layer is dried according to the present invention. The resulting three-dimensional object is then subsequently debound and then sintered to provide the stainless steel three-dimensional object.

It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-discussed embodiments may be used in combination with each other. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description.

The benefits and advantages which may be provided by the present invention have been described above with regard to specific embodiments. These benefits and advantages, and any elements or limitations that may cause them to occur or to become more pronounced are not to be construed as critical, required, or essential features of any or all of the embodiments.

While the present invention has been described with reference to particular embodiments, it should be understood that the embodiments are illustrative and that the scope of the invention is not limited to these embodiments. Many variations, modifications, additions and improvements to the embodiments described above are possible. It is contemplated that these variations, modifications, additions and improvements fall within the scope of the invention.

Incorporation by Reference The entire disclosure of each of the patent documents, including certificates of correction, patent application documents, scientific articles, governmental reports, websites, and other references referred to herein is incorporated by reference herein in its entirety for all purposes. In case of a conflict in terminology, the present specification controls.

Equivalents

The invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The foregoing embodiments are to be considered in all respects illustrative rather than limiting on the invention described herein. In the various embodiments of the methods and systems of the present invention, where the term comprises is used with respect to the recited steps of the methods or components of the compositions, it is also contemplated that the methods and compositions consist essentially of, or consist of, the recited steps or components. Furthermore, it should be understood that the order of steps or order for performing certain actions is immaterial so long as the invention remains operable. Moreover, two or more steps or actions can be conducted simultaneously.

In the specification, the singular forms also include the plural forms, unless the context clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In the case of conflict, the present specification will control.

Furthermore, it should be recognized that in certain instances a composition can be described as being composed of the components prior to mixing, or prior to a further processing step such as drying, binder removal, heating, sintering, etc. It is recognized that certain components can further react or be transformed into new materials.

All percentages and ratios used herein are on a volume (volume/volume) or weight (weight/weight) basis as shown, or otherwise indicated.