Method and apparatus for manufacturing three-dimensional formed object, and system for forming

Abstract

To provide a method for manufacturing a three-dimensional formed object excellent in forming quality with a reduced number of steps.SOLUTION: A method for manufacturing a three-dimensional formed object includes: a green body forming step that forms a green body in a forming tank using a powder; a drying step that dries the green body in the forming tank; a pressurizing step that pressurizes the green body dried in the forming tank; a defatted-body forming step that forms a defatted body from the green body pressurized; and a sintered body forming step that forms a sintered body by heating the defatted body.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for manufacturing a three-dimensional object, and a modeling system. [Background technology]

[0002] Known methods for forming a molded object include, for example, the SLS method, which selectively irradiates with a laser, the EBM method, which irradiates with an electron beam, and the binder jet (BJ) method, which applies a binding liquid (molding liquid).

[0003] Furthermore, as a three-dimensional modeling method, for example, a three-dimensional modeling method has been proposed that includes an additive manufacturing process in which secondary particles obtained by granulating primary particles are stacked to produce a three-dimensional object, and a sintering process in which the three-dimensional object is heated to produce a sintered body (see, for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a method for manufacturing a three-dimensional object with improved productivity and high quality. [Means for solving the problem]

[0005] The method for manufacturing a three-dimensional object of the present invention as a means for solving the above problems comprises the steps of: a green body forming step of forming a green body in a building tank using the powder; a drying step of drying the green body in the building tank; a pressurizing step of pressurizing the dried green body in the building tank; a degreased body forming step of forming a degreased body from the pressed green body; and a sintered body forming step of heating the degreased body to form a sintered body. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a method for manufacturing a three-dimensional object with improved productivity and high quality. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram of a green body forming means according to one embodiment of the present invention. [Figure 2A] FIG. 2A is a schematic explanatory view (part 1) for explaining a green body forming step according to one embodiment of the present invention. [Figure 2B] FIG. 2B is a schematic explanatory view (part 2) for explaining the green body forming step according to one embodiment of the present invention. [Figure 2C] FIG. 2C is a schematic explanatory view (part 3) for explaining the green body forming step according to one embodiment of the present invention. [Figure 2D] FIG. 2D is a schematic explanatory view (part 4) for explaining the green body forming step according to one embodiment of the present invention. [Figure 2E] FIG. 2E is a schematic explanatory view for explaining the green body forming step according to one embodiment of the present invention (part 5). [Figure 3] FIG. 3 is a flowchart showing a method for manufacturing a three-dimensional object according to one embodiment of the present invention. [Figure 4] FIG. 4 is a schematic explanatory diagram of a modeling system according to one embodiment of the present invention. [Figure 5] FIG. 5 is a schematic diagram for explaining the amount of deformation of the sintered body in the example. DETAILED DESCRIPTION OF THE INVENTION

[0008] Conventionally, three-dimensional objects are manufactured by applying a manufacturing liquid to a powder layer containing powder to form a green body, followed by processes such as a pressurizing process, a degreasing process, and a sintering process. In such conventional manufacturing methods, the unpressurized (not sufficiently solidified) green body needs to be removed from the manufacturing tank before being introduced into a pressurizing device, and the green body may be damaged during this process. In other words, conventional manufacturing methods for three-dimensional objects, including those described in Patent Document 1, have raised concerns about a decline in manufacturing quality. Furthermore, from the perspective of improving productivity, there is also room for improvement in the number of manufacturing steps.

[0009] The method for manufacturing a three-dimensional object of the present invention includes a green body forming step of forming a green body in a manufacturing tank using powder, a drying step of drying the green body in the manufacturing tank, a pressurizing step of pressing the dried green body in the manufacturing tank, a degreased body forming step of forming a degreased body from the pressed green body, and a sintered body forming step of heating the degreased body to form a sintered body. Therefore, it is possible to improve productivity and realize a manufacturing method for a high-quality three-dimensional object.

[0010] The present invention will be described in detail below.

[0011] (Method for manufacturing a three-dimensional object and an apparatus for manufacturing a three-dimensional object) The method for manufacturing a three-dimensional object of the present invention includes a green body forming step, a drying step, a pressing step, a degreased body forming step, and a sintered body forming step, and may include other steps as necessary. The apparatus for manufacturing a three-dimensional object of the present invention includes a green body forming means, a drying means, a pressurizing means, a degreased body forming means, and a sintered body forming means, and may include other means as necessary. The method for manufacturing a three-dimensional object can be suitably carried out by a three-dimensional object manufacturing apparatus, the green body forming step can be suitably carried out by a green body forming means, the drying step can be suitably carried out by a drying means, the pressurizing step can be suitably carried out by a pressurizing means, the degreased body forming step can be suitably carried out by a degreased body forming means, the sintered body forming step can be suitably carried out by a sintered body forming step, and the other steps can be suitably carried out by other means.

[0012] <Green Body Forming Step and Green Body Forming Means> The green body forming step is a step of forming a green body in a building tank using powder. The green body forming step is preferably a step of forming a green body by repeating a powder layer forming step and a modeling liquid applying step. The green body forming means is a means for forming a green body in a building tank using powder. The green body forming means preferably includes a powder layer forming means and a modeling liquid applying means. Since the build tank contains powder, the green body is buried in the powder in the build tank.

[0013] In this specification, the "powder layer" formed by the powder layer forming process and the layer formed by the modeling liquid application process (hereinafter sometimes referred to as the "modeling layer") refer to a single layer formed by each process. In this specification, the term "green body" refers to a stack of modeling layers formed by repeating the powder layer forming step and the modeling liquid applying step.

[0014] <<Powder layer forming step and powder layer forming means>> The powder layer forming step is a step of forming a powder layer using powder. The powder layer forming means is a means for forming a powder layer using a powder. The powder layer forming step can be suitably carried out by the powder layer forming means. The powder layer forming means is not particularly limited and can be appropriately selected depending on the purpose, and for example, a recoating member, a hopper, etc. Among the powder layer forming means, a means having the function of flattening the powder layer is sometimes called a "flattening means."

[0015] -Powder- The powder is not particularly limited and can be appropriately selected depending on the purpose, but preferably contains metal particles. The powder may further contain a ceramic filler and, if necessary, other components. Other components in the powder are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include leveling agents, sintering aids, polymer resin particles, and the like. Leveling agents are effective in controlling the wettability of the powder surface. For example, improving the wettability of the powder makes it easier for the modeling liquid to penetrate, increasing the strength of the green body and resulting in high-quality three-dimensional objects. Sintering aids are materials that promote sintering when sintering green bodies. For example, they can increase the density and strength of three-dimensional objects, resulting in high-quality three-dimensional objects. They also improve productivity by enabling sintering to be completed at low temperatures and in a short time. Polymer resin particles are an effective material for increasing the fluidity of powders, for example, by increasing the density of the green body and increasing its strength, resulting in high-quality three-dimensional objects.

[0016] --Metal particles-- Metal particles are particles that contain metal as a constituent material. The constituent material of the metal particles is not particularly limited as long as it contains a metal, and may contain materials other than metal, but it is preferable that the main material is metal. Here, "mainly metal" means that the mass of the metal contained in the metal particles is 50.0 mass% or more relative to the total mass of the metal particles. The mass of the metal contained in the metal particles is preferably 60.0 mass% or more, more preferably 70.0 mass% or more, even more preferably 80.0 mass% or more, and particularly preferably 90.0 mass% or more relative to the total mass of the metal particles.

[0017] The metal is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include aluminum (Al), magnesium (Mg), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), lead (Pd), silver (Ag), indium (In), tin (Sn), tantalum (Ta), tungsten (W), neodymium (Nd), and alloys of these metals. Among these, aluminum (Al), stainless steel (SUS), iron (Fe), copper (Cu), silver (Ag), titanium (Ti), and alloys of these metals are preferred due to their high versatility as metals, and pure aluminum (pure Al) and aluminum alloys (Al alloys) are more preferred. These may be used alone or in combination of two or more.

[0018] Examples of aluminum alloys include AlSi10Mg, AlSi12, AlSi7Mg0.6, AlSi3Mg, AlSi9Cu3, Scalmalloy, ADC12, and AlSi3.

[0019] The metal particles to be used may be appropriately manufactured or commercially available. Metal particles can be produced by a conventionally known method. Examples of methods for producing metal particles include a pulverization method in which a solid is subjected to compression, impact, friction, or the like to be broken down into small particles, an atomization method in which a molten metal is sprayed to obtain a rapidly cooled powder, a precipitation method in which a component dissolved in a liquid is precipitated, and a gas-phase reaction method in which vaporization and crystallization occur. Among these, the atomization method is preferred because it produces particles with a spherical shape and little variation in particle size. Examples of atomization methods include water atomization, gas atomization, centrifugal atomization, and plasma atomization, and any of these methods can be suitably used.

[0020] Commercially available metal particles include, for example, AlSi10Mg powder (Si10Mg-30BB, average particle size 35 μm, manufactured by Toyo Aluminum K.K.), pure Al (A1070-30BB, manufactured by Toyo Aluminum K.K.), pure Ti (manufactured by Osaka Titanium Technologies Co., Ltd.), and SUS316L (PSS316L, manufactured by Sanyo Special Steel Co., Ltd.).

[0021] The volume average particle size of the metal particles is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 2 μm or more and 100 μm or less, and more preferably 8 μm or more and 50 μm or less. When the volume average particle size of the metal particles is 2 μm or more, aggregation of the metal particles is suppressed, and the production efficiency of the green body and the handleability of the metal particles can be improved. When the volume average particle size of the metal particles is 100 μm or less, it is possible to prevent a decrease in contact points between the metal particles and an increase in voids, and it is possible to prevent a decrease in the strength of the green body.

[0022] The particle size distribution of the metal particles is not particularly limited and can be appropriately selected depending on the purpose, but a sharper distribution is preferable. The volume average particle size and particle size distribution of the metal particles can be measured using a known particle size measuring device, such as a particle size distribution measuring device Microtrac MT3000II series (manufactured by Microtrac Bell).

[0023] --Ceramic filler-- The ceramic filler is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include inorganic nitrides, carbides, borides, and oxides of zirconium, tantalum, titanium, tungsten, silicon, aluminum, beryllium, etc. Specific examples of ceramic fillers include alumina (Al2O3), zirconia (ZrO2), silicon carbide (SiC), aluminum nitride, beryllia, zirconium nitride, zirconium boride, titanium nitride, titanium oxide, silicon oxide, tantalum carbide, tungsten carbide, zirconium carbide, titanium carbide, aluminum boride, and titanium boride. Among these, alumina (Al2O3), zirconia (ZrO2), and silicon carbide (SiC) are preferred. These ceramic fillers remain as solids without becoming liquid during the sintered body formation process and function as a skeleton that supports the sintered body, thereby suppressing deformation of the sintered body after sintering.

[0024] The content of the ceramic filler is not particularly limited and can be selected appropriately depending on the purpose, but from the viewpoint of achieving a good effect of suppressing deformation of the sintered body after sintering, it is preferably 5 vol% or more and 30 vol% or less, and more preferably 5 vol% or more and 20 vol% or less, of the total amount of powder.

[0025] The average particle size of the ceramic filler is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 20 μm or more and 100 μm or less. When the average particle size of the ceramic filler is 20 μm or more, the aggregation of the ceramic filler is suppressed and the ceramic filler is uniformly distributed in the sintered body, thereby suppressing deformation of the sintered body. When the average particle size of the ceramic filler is 100 μm or less, a green body can be molded even with a narrow layer pitch, and the layer step difference can be reduced, thereby improving the dimensional accuracy of the molded product.

[0026] The angle of repose of the powder is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 60° or less, more preferably 40° or less, so that the powder can be stably placed in a predetermined area. The angle of repose of a powder can be measured, for example, using a powder property measuring device (Powder Tester PT-N type, manufactured by Hosokawa Micron Corporation).

[0027] <<Modeling fluid application process and modeling fluid application means>> The modeling liquid application step is a step of applying a modeling liquid to the powder layer. The modeling liquid applying means is a means for applying the modeling liquid to the powder layer. The modeling liquid applying step can be suitably carried out by the modeling liquid applying means.

[0028] The modeling liquid application means is not particularly limited and can be appropriately selected depending on the purpose, and examples include a dispenser method, a spray method, an inkjet method, etc. Among these, the inkjet method is preferred from the viewpoint of being able to precisely and efficiently form a complex modeled object, as it has the advantages of being able to dispense droplets more quantitatively than the spray method and being able to apply a larger area than the dispenser method.

[0029] When an inkjet method is used as the modeling liquid applying means, the modeling liquid applying means is an inkjet head having nozzles for ejecting the modeling liquid. As the inkjet head, an inkjet head in a known inkjet printer can be suitably used.

[0030] -Modeling liquid- The molding liquid is not particularly limited and can be appropriately selected depending on the purpose. For example, it contains a resin and an organic solvent, and may contain additives and other components as needed.

[0031] --resin-- The resin in the modeling liquid functions as a binder. The resin is not particularly limited and can be appropriately selected depending on the purpose, but it is preferable to contain a resin having at least one structural unit selected from the structural unit represented by structural formula (1) and the structural unit represented by structural formula (2). In this specification, the term "structural unit" refers to a partial structure in the resin derived from one or more polymerizable compounds.

[0032] [ka]

[0033] [ka]

[0034] ---Resin having a structural unit represented by structural formula (1)--- The resin having the structural unit represented by structural formula (1) is placed in the powder layer when the modeling liquid is applied to the powder layer containing metal particles, and by undergoing appropriate heating according to the softening point of the resin, it functions as a binder that binds the metal particles together in the area where the modeling liquid is applied, forming a green body. This green body has improved bending strength because it is formed from a resin having the structural unit represented by structural formula (1), which imparts flexibility.

[0035] Resins having structural units represented by structural formula (1) have excellent thermal decomposition properties, allowing them to be appropriately removed in the degreased body formation process, resulting in improved density in the sintered body produced through the subsequent sintered body formation process. Therefore, when metal particles, which are intended to be sintered or are preferred for sintering, are used as the material for forming the three-dimensional object, the resulting effect is particularly pronounced. Specifically, when the resin having structural units represented by structural formula (1) is heated from 30°C to 550°C, it is preferable that 95% by mass or more, and more preferably 97% by mass or more, of the resin is thermally decomposed. In this specification, the phrase "thermal decomposition of resin" means that random decomposition of the main chain or depolymerization at the molecular chain terminal occurs, and the resin is removed by vaporization, oxidative decomposition, combustion, or the like. Thermal decomposition can be measured using a TG-DTA (thermogravimetric and differential thermal analyzer) by heating the sample from 30°C to 550°C at a rate of 10°C / min in air or nitrogen atmosphere, and then holding the temperature at 550°C for 2 hours, after which the weight loss rate is measured.

[0036] Furthermore, the resin having the structural unit represented by structural formula (1) has improved solubility in organic solvents due to the hydrophobicity of the structural unit represented by structural formula (1). Therefore, when the modeling liquid contains an organic solvent, the solubility of the resin having the structural unit represented by structural formula (1) is improved, which in turn reduces the viscosity of the modeling liquid, allowing the modeling liquid to be appropriately ejected, for example, by an inkjet method. Note that the resin having the structural unit represented by structural formula (1) is preferably soluble in the organic solvent of the modeling liquid and insoluble in water.

[0037] The glass transition temperature (Tg) of the resin having the structural unit represented by structural formula (1) is preferably 0°C or higher, more preferably 10°C or higher, and even more preferably 20°C or higher. The glass transition temperature (Tg) of the resin having the structural unit represented by structural formula (1) is preferably 100°C or lower, more preferably 90°C or lower, and even more preferably 80°C or lower.

[0038] The softening point of the resin having the structural unit represented by structural formula (1) is preferably 70°C or higher, more preferably 80°C or higher, and even more preferably 90°C or higher. The softening point of the resin having the structural unit represented by structural formula (1) is preferably 150°C or lower, more preferably 140°C or lower, and even more preferably 130°C or lower.

[0039] The number average molecular weight (Mn) of the resin having the structural unit represented by structural formula (1) is preferably from 5,000 to 50,000, and more preferably from 10,000 to 30,000. When the number average molecular weight (Mn) of the resin having the structural unit represented by structural formula (1) is within the above range, it is possible to simultaneously achieve improvements in strength and modeling accuracy, a reduction in the viscosity of the modeling liquid, and an improvement in the resin concentration in the modeling liquid.

[0040] The resin having a structural unit represented by structural formula (1) may be either a resin having a structural unit represented by a formula other than structural formula (1) or a resin having no structural unit represented by a formula other than structural formula (1). Preferred structural units represented by a formula other than structural formula (1) include, for example, structural units represented by structural formula (3) and structural formula (4).

[0041] [ka]

[0042] [ka]

[0043] A resin having a structural unit represented by structural formula (3) in addition to a structural unit represented by structural formula (1) improves the bending strength of the green body. The structural unit represented by structural formula (3) also has hydrophobicity similar to the structural unit represented by structural formula (1), and this improves the solubility of the resin in organic solvents.

[0044] A resin having a structural unit represented by structural formula (4) in addition to a structural unit represented by structural formula (1) improves affinity with metal particles in the powder layer to which the modeling liquid is applied due to the hydroxyl group in the structural unit represented by structural formula (4), thereby further improving the bending strength of the green body, and further improving the density of the green body and the density of the modeled product after sintering.

[0045] Specific examples of resins having a structural unit represented by structural formula (1) include polyvinyl acetate resin, partially saponified polyvinyl acetate resin, polyvinyl butyral resin, etc. Among these, polyvinyl acetate resin and partially saponified polyvinyl acetate resin are preferred because they can reduce the viscosity of the modeling liquid. In this specification, the term "partially saponified polyvinyl acetate resin" refers to a polyvinyl acetate resin that has been partially saponified. These resins may be used alone or in combination of two or more, and either commercially available products or synthetic products may be used.

[0046] The polyvinyl acetate resin is a resin that has a structural unit represented by structural formula (1) and is substantially free of a structural unit represented by structural formula (3) and a structural unit represented by structural formula (4). The partially saponified polyvinyl acetate resin is a resin having a structural unit represented by structural formula (1) and a structural unit represented by structural formula (4), and substantially no structural unit represented by structural formula (3). The polyvinyl butyral resin is a resin having a structural unit represented by structural formula (1) and a structural unit represented by structural formula (3), or a resin having a structural unit represented by structural formula (1), a structural unit represented by structural formula (3), and a structural unit represented by structural formula (4).

[0047] The content of the resin having the structural unit represented by structural formula (1) is preferably 5.0 mass% or more, more preferably 7.0 mass% or more, even more preferably 10.0 mass% or more, and particularly preferably 11.0 mass% or more, based on the total mass of the modeling liquid. Also, the content of the resin having the structural unit represented by structural formula (1) is preferably 30.0 mass% or less, more preferably 25.0 mass% or less, and even more preferably 20.0 mass% or less, based on the total mass of the modeling liquid. When the content of the resin having the structural unit represented by structural formula (1) is 5.0% by mass or more, the bending strength of the green body is further improved. When the content of the resin having the structural unit represented by structural formula (1) is 30.0 mass % or less, the viscosity of the modeling liquid is further reduced, and the modeling liquid can be appropriately ejected using, for example, an inkjet method.

[0048] ---Resin having a structural unit represented by structural formula (2)--- The resin having the structural unit represented by structural formula (2) is placed in the powder layer when the modeling liquid is applied to the powder layer containing metal particles, and by undergoing appropriate heating according to the softening point of the resin, it functions as a binder that binds the metal particles together in the area where the modeling liquid is applied, forming a green body. These green bodies are formed from resins having the structural unit represented by structural formula (2), which has a five-membered ring lactam structure that has a high affinity for metals, so the metal particles are firmly bound together and bending strength is improved.

[0049] Resins having structural units represented by structural formula (2) have excellent thermal decomposition properties when the temperature rise profile is appropriately controlled. Therefore, the resins are appropriately removed in the degreased body formation process, and the density of the sintered body produced through the subsequent sintered body formation process is improved. Therefore, when metal particles, which are intended to be sintered or are preferred to be sintered, are used as the material for forming the shaped object, the effect obtained is significant. Specifically, when the resin having structural units represented by structural formula (2) is heated from 30°C to 550°C, it is preferable that 95% by mass or more, and more preferably 97% by mass or more, of the resin is thermally decomposed.

[0050] Furthermore, the resin having the structural unit represented by structural formula (2) has a five-membered ring lactam structure, which improves its solubility in certain organic solvents (mainly polar solvents). This reduces the viscosity of the modeling liquid, allowing the modeling liquid to be appropriately ejected using, for example, an inkjet method.

[0051] The softening point of the resin having the structural unit represented by structural formula (2) is preferably 70°C or higher, more preferably 80°C or higher, and even more preferably 90°C or higher. The softening point of the resin having the structural unit represented by structural formula (2) is preferably 180°C or lower, more preferably 170°C or lower, and even more preferably 160°C or lower.

[0052] The number average molecular weight (Mn) of the resin having the structural unit represented by structural formula (2) is preferably 3,000 or more and 50,000 or less, and more preferably 5,000 or more and 40,000 or less. The number average molecular weight (Mn) of the resin having the structural unit represented by structural formula (2) is 3,000 or more and 50,000 or less, which makes it possible to simultaneously improve the strength and molding accuracy, reduce the viscosity of the molding liquid, and improve the resin concentration in the molding liquid.

[0053] Specific examples of resins having a structural unit represented by structural formula (2) include polyvinylpyrrolidone resins, etc. The resin having a structural unit represented by structural formula (2) may be appropriately synthesized or may be a commercially available product.

[0054] The content of the resin having the structural unit represented by structural formula (2) is preferably 7.0 mass% or more, more preferably 10.0 mass% or more, even more preferably 11.0 mass% or more, and particularly preferably 13.0 mass% or more, relative to the total mass of the modeling liquid. Also, the content of the resin having the structural unit represented by structural formula (2) is preferably 25.0 mass% or less, more preferably 20.0 mass% or less, and even more preferably 15.0 mass% or less, relative to the total mass of the modeling liquid. When the content of the resin having the structural unit represented by structural formula (2) is 7.0 mass % or more relative to the total mass of the modeling liquid, the bending strength of the green body is further improved. When the content of the resin having the structural unit represented by structural formula (2) is 25.0 mass% or less relative to the total mass of the modeling liquid, the viscosity of the modeling liquid is further reduced, and the modeling liquid can be appropriately ejected using, for example, an inkjet method.

[0055] --Organic solvents-- The organic solvent is a liquid component used to make the modeling liquid liquid at room temperature. The modeling liquid preferably contains an organic solvent, making it a non-aqueous modeling liquid. In this specification, the term "non-aqueous modeling liquid" refers to a modeling liquid that contains an organic solvent as a liquid component, and in which the organic solvent is the component with the largest mass among the liquid components. The content of the organic solvent relative to the content of the liquid components in the modeling liquid is preferably 90.0 mass% or more, and more preferably 95.0 mass% or more. A non-aqueous modeling liquid improves the solubility of resins, particularly those having a structural unit represented by Structural Formula (1), and reduces the viscosity of the modeling liquid, allowing the modeling liquid to be appropriately ejected using an inkjet method. In addition, a non-aqueous modeling liquid can sometimes be rephrased as a modeling liquid that does not substantially contain water, which makes it possible to apply the modeling liquid even when the material constituting the metal particles is a highly reactive metal (a water-rejecting material such as aluminum, zinc, or magnesium).

[0056] The boiling point of the organic solvent is not particularly limited and can be selected appropriately depending on the purpose, but a high boiling point is preferable. Specifically, a boiling point of 150°C or higher is preferable, and a boiling point of 180°C or higher is more preferable. When the modeling liquid is ejected using an inkjet method or the like, a high boiling point of the organic solvent is preferable because it can prevent the modeling liquid from drying in the nozzle or near the nozzle and prevent nozzle clogging due to precipitated resin. Examples of high-boiling organic solvents include γ-butyrolactone (boiling point: 204°C), propylene carbonate (boiling point: 242°C), cyclohexanone (boiling point: 155.6°C), diethylene glycol dimethyl ether (boiling point: 162°C), and triethylene glycol dimethyl ether (boiling point: 216°C). In addition to these organic solvents, for example, n-octane, m-xylene, solvent naphtha, diisobutyl ketone, 3-heptanone, 2-octanone, acetylacetone, butyl acetate, amyl acetate, n-hexyl acetate, n-octyl acetate, ethyl butyrate, ethyl valerate, ethyl caprylate, ethyl octanoate, ethyl acetoacetate, ethyl 3-ethoxypropionate, diethyl oxalate, diethyl malonate, diethyl succinate, diethyl adipate, bis-2-ethylhexyl maleate, and triacetin , tributyrin, propylene glycol monomethyl ether acetate, ethylene glycol monobutyl ether acetate, dibutyl ether, 1,2-dimethoxybenzene, 1,4-dimethoxybenzene, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, 2-methoxy-1-methylethyl acetate, γ-butyrolactone, propylene carbonate, cyclohexanone, and butyl cellosolve can also be used. These may be used alone or in combination of two or more.

[0057] The viscosity of the organic solvent is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 5.0 mPa·s or more and 50.0 mPa·s or less, and more preferably 8.0 mPa·s or more and 30.0 mPa·s or less, at 25°C. When the viscosity of the organic solvent is 5.0 mPa·s or more and 50.0 mPa·s or less at 25°C, the viscosity of the modeling liquid containing the organic solvent is also easily reduced, stabilizing the ejection from the modeling liquid application means, such as an inkjet head. Furthermore, accurate ejection of the modeling liquid further improves the bending strength of the green body and also improves dimensional accuracy. The viscosity of the organic solvent can be measured, for example, in accordance with JIS K7117.

[0058] When a resin having a structural unit represented by Structural Formula (1) is used as the resin contained in the modeling liquid, the organic solvent used in combination is not particularly limited, but for example, it is preferable to use an organic solvent having at least one structure selected from an alkoxy group, an ether bond, and an ester bond, it is more preferable to use an organic solvent having an ether bond, and alkylene glycol dialkyl ethers are particularly preferable. When such an organic solvent is used, the solubility of the resin having the structural unit represented by Structural Formula (1) is further improved, which in turn can further reduce the viscosity of the modeling liquid, allowing the modeling liquid to be appropriately ejected, for example, by an inkjet method.

[0059] In this specification, "alkylene glycol dialkyl ethers" are represented by R1-(O-R2)m-OR3. Here, R1 and R3 are each independently an alkyl group having 1 to 5 carbon atoms, which may be linear or branched, and preferably has 1 or 2 carbon atoms. R2 is an alkylene group having 2 to 5 carbon atoms, which may be linear or branched, and more preferably has 2 or 3 carbon atoms. m represents an integer of 1 to 5, and more preferably 2 or 3. Specific examples of alkylene glycol dialkyl ethers include diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol butyl methyl ether, etc. Among these, diethylene glycol dimethyl ether and triethylene glycol dimethyl ether are preferred, and triethylene glycol dimethyl ether is more preferred.

[0060] When a resin having a structural unit represented by Structural Formula (2) is used as the resin contained in the modeling liquid, it is preferable that the organic solvent used in combination is a polar solvent. Specifically, it is preferable to use at least one selected from Component 1, which is a group consisting of cyclic esters (lactones), cyclic ketones, and alkylene glycol monoalkyl ethers. It is more preferable to use at least one selected from Component 2, which is a group consisting of alkylene glycol dialkyl ethers, in addition to at least one selected from Component 1. When such an organic solvent is used, the solubility of the resin having a structural unit represented by Structural Formula (2) is further improved, thereby further reducing the viscosity of the modeling liquid, and enabling the modeling liquid to be appropriately ejected, for example, by an inkjet method. Note that, from the viewpoint of further improving the solubility of the resin having a structural unit represented by Structural Formula (2), it is preferable that Component 1 is a group consisting of cyclic esters (lactones) and cyclic ketones.

[0061] Specific examples of component 1, which is a group consisting of cyclic esters (lactones), cyclic ketones, and alkylene glycol monoalkyl ethers, include γ-butyrolactone, propylene carbonate, and cyclohexanone. Specific examples of component 2, which is a group consisting of alkylene glycol dialkyl ethers, include diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol butyl methyl ether, etc. Among these, diethylene glycol dimethyl ether and triethylene glycol dimethyl ether are preferred.

[0062] In this specification, "alkylene glycol monoalkyl ethers" are represented by R4-(O-R5)n-OH. Here, R4 is an alkyl group having 1 to 5 carbon atoms, which may be linear or branched. R5 is an alkylene group having 2 to 5 carbon atoms, which may be linear or branched. n is an integer of 1 to 5.

[0063] The content of the organic solvent is preferably 60.0% by mass or more and 95.0% by mass or less, and more preferably 70.0% by mass or more and 95.0% by mass or less, relative to the total mass of the modeling liquid. When the content of the organic solvent is 60.0% by mass or more and 95.0% by mass or less, relative to the total mass of the modeling liquid, the solubility of the resin is further improved, and as a result, the viscosity of the modeling liquid can be further reduced, and the modeling liquid can be appropriately ejected using, for example, an inkjet system.

[0064] --Additives-- The modeling liquid may contain additives such as surfactants, drying inhibitors, viscosity adjusters, penetrants, antifoaming agents, pH adjusters, preservatives, antifungal agents, colorants, preservatives, and stabilizers, depending on the purpose. For example, surfactants are added to adjust the surface tension of the modeling liquid. Conventionally known materials can be used for these additives.

[0065] --Other ingredients-- Other components contained in the molding liquid include, for example, water. The other components contained in the modeling liquid can be selected appropriately taking into consideration various conditions such as the type of modeling liquid application means, frequency of use, and amount.For example, when the modeling liquid is applied by a liquid ejection method, the components can be selected taking into consideration the effects of clogging the nozzles of the liquid ejection head, etc.

[0066] The modeling liquid does not substantially contain water. In this specification, "substantially does not contain water" means that water is not actively used as a material in the production of the modeling liquid, or that the water content in the modeling liquid is below the detection limit when using a publicly known and common technical knowledge method. More specifically, this means that the water content is 10.0 mass% or less with respect to the total mass of the modeling liquid. The water content is preferably 5.0 mass% or less with respect to the total mass of the modeling liquid, more preferably 3.0 mass% or less, and even more preferably 1.0 mass% or less, and it is particularly preferable that the modeling liquid does not contain water. Since the modeling liquid is substantially free of water, the solubility of the resin is improved, which in turn reduces the viscosity of the modeling liquid. Furthermore, the formation of a hydrogel, which contains a large amount of water around the resin, is suppressed, which in turn suppresses the increase in viscosity of the modeling liquid. Therefore, the modeling liquid can be appropriately ejected using, for example, an inkjet method.

[0067] --Manufacturing method of modeling liquid-- The method for producing the modeling liquid is not particularly limited and can be appropriately selected depending on the purpose. For example, a method in which various materials are mixed and stirred can be used.

[0068] --Physical properties of modeling liquid-- The viscosity of the modeling liquid is not particularly limited and can be selected appropriately depending on the purpose, but a low viscosity is preferable. Specifically, at 25°C, a viscosity of 5 mPa·s or more and 50 mPa·s or less is preferable, more preferably 5 mPa·s or more and 40 mPa·s or less, and even more preferably 5 mPa·s or more and 30 mPa·s or less is preferable. When the viscosity of the modeling liquid at 25°C is 5 mPa·s or more and 50 mPa·s or less, the ejection from the modeling liquid applying means such as an inkjet head is stabilized, and the accurate ejection of the modeling liquid further improves the bending strength of the green body and also improves dimensional accuracy. The viscosity can be measured, for example, in accordance with JIS K7117.

[0069] The surface tension of the modeling liquid is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 40 mN / m or less, and more preferably 10 mN / m or more and 30 mN / m or less, at 25° C. If the surface tension of the modeling liquid is 40 mN / m or less, the ejection from the modeling liquid applying means such as an inkjet head is stabilized, and the accurate ejection of the modeling liquid further improves the bending strength of the green body and also improves the dimensional accuracy. The surface tension can be measured, for example, using a DY-300 manufactured by Kyowa Interface Science Co., Ltd.

[0070] Here, an embodiment of the method for manufacturing a three-dimensional object according to the present invention will be described with reference to the drawings. However, the use of the method for manufacturing a three-dimensional object according to the present invention is not limited to these embodiments. In each drawing, the same components are denoted by the same reference numerals, and redundant explanations may be omitted. Furthermore, the number, position, shape, etc. of the following components are not limited to this embodiment, and may be any number, position, shape, etc. that is preferable for implementing the present invention.

[0071] [Figure 1] FIG. 1 is a schematic diagram of a green body forming means according to one embodiment of the present invention.

[0072] The molding apparatus 100 serving as the green body forming means includes a powder layer forming means 1 and a molding liquid applying means 5. The powder layer forming means 1 forms a powder layer 31 containing powder 20. The modeling liquid applying means 5 applies the modeling liquid 10 to the powder layer 31 to form a modeling layer 30. The molding apparatus 100 forms a green body as a stack of multiple molding layers 30.

[0073] -Powder layer forming means- The powder layer forming means 1 includes a powder tank 11 and a lamination unit 16 . The powder tank 11 includes a supply tank 21, a modeling tank 22, a supply stage 23, a modeling stage 24, and a surplus powder tank 25. The powder tank 11 has a box-like shape. The tops of the supply tank 21, the modeling tank 22, and the surplus powder tank 25 are open. The lamination unit 16 includes a flattening section 12 as a flattening means, and a powder removing section 13 .

[0074] The supply tank 21 is a tank that supplies the powder 20 to the modeling tank 22. The supply tank 21 also holds the powder 20 to be supplied to the modeling tank 22. A supply stage 23 is provided at the bottom of the supply tank 21. The supply stage 23 moves up and down in the vertical direction (Z direction). The side of the supply stage 23 is disposed so as to contact the inner surface of the supply tank 21. The upper surface of the supply stage 23 is kept horizontal.

[0075] The powder 20 required for modeling is supplied from the supply tank 21 to the modeling tank 22. A powder layer 31 and a modeling layer 30 are formed in the modeling tank 22. Furthermore, a plurality of modeling layers 30 are stacked in the modeling tank 22 to form a green body. Since the modeling tank 22 contains the powder 20, the green body is buried in the powder 20 in the modeling tank 22. The modeling tank 22 is detachable. A modeling stage 24 is provided at the bottom of the modeling tank 22. The modeling stage 24 moves up and down in the vertical direction (Z direction). The side of the modeling stage 24 is disposed so as to contact the inner surface of the modeling tank 22. The upper surface of the modeling stage 24 is kept horizontal.

[0076] The surplus powder tank 25 is a tank that holds surplus powder 20 among the powder 20 flattened by the flat portion 12 when forming the powder layer 31. A means for sucking the powder 20 may be provided at the bottom of the surplus powder tank 25, or the surplus powder tank 25 may be configured to be removable. The surplus powder tank 25 is disposed next to the modeling tank 22. The surplus powder 20 held in the surplus powder tank 25 may be returned to the supply tank 21, or may be returned to the supply tank 21 via a powder supply device. The powder supply device may be disposed above the supply tank 21, and may supply the powder 20 to the supply tank 21 before the start of modeling or when the amount of powder 20 in the supply tank 21 decreases. Note that the powder tank 11 may have only the modeling tank 22, and powder may be supplied to the modeling tank 22 from the powder supply device. Methods for transporting the powder 20 from the powder supply device to the supply tank 21 include a screw conveyor system using a screw, and a pneumatic transport system using air.

[0077] The flattening unit 12 flattens the modeling layer 30 and the powder layer 31. The flattening unit 12 flattens the modeling layer 30 by rotating the recoater as a rotating body. When the flattening unit 12 is driven to rotate, the powder 20 from the supply stage 23 of the supply tank 21 is supplied to the modeling tank 22, forming the powder layer 31. The flattening unit 12 moves back and forth in the Y direction along the stage surface (the surface on which the powder 20 is loaded) of the modeling stage 24. More specifically, the flattening unit 12 moves horizontally from the outside of the supply tank 21, passing above the supply tank 21 and the modeling tank 22. As a result, the powder 20 is transferred and supplied onto the modeling tank 22, and the flattening unit 12 passes over the modeling tank 22, thereby forming the powder layer 31. The flattening unit 12 is a member longer than the inner dimensions of the modeling tank 22 and the supply tank 21. Note that the flattening unit 12 may be a blade or a bar as a plate-like member.

[0078] Powder removal unit 13 removes powder adhering to flat portion 12. Powder removal unit 13 moves together with flat portion 12 while being in contact with the circumferential surface of flat portion 12.

[0079] -Modeling liquid application means- The modeling liquid applying means 5 includes a carriage 51 and a head 52 . The head 52 applies the modeling liquid 10 to the powder layer 31. The head 52 is, for example, an inkjet head, and has a nozzle row in which a plurality of nozzles are arranged. A colored model may be formed by applying a cyan modeling liquid, a magenta modeling liquid, a yellow modeling liquid, and a black modeling liquid, or a single color modeling liquid may be applied from multiple nozzles. The modeling liquid may be applied by an inkjet method or a dispenser method. At least one head 52 is mounted on a carriage 51, and is reciprocated in the X (main scanning), Y (sub-scanning), and Z directions by a motor, a guide member, and the like.

[0080] [Figure 2] Next, a description will be given of a green body forming step that is performed using the molding apparatus 100 shown in Fig. 1. Figs. 2A to 2E are schematic explanatory views for explaining the green body forming step according to one embodiment of the present invention.

[0081] FIG. 2A shows a state in which a first modeling layer 30 is formed on the modeling stage 24 of the modeling tank 22. First, the supply stage 23 of the supply tank 21 is raised in the Z1 direction, and the modeling stage 24 of the modeling tank 22 is lowered in the Z2 direction. At this time, the lowering distance of the modeling stage 24 is set so that the distance between the upper surface of the modeling tank 22 (the surface on which the powder layer is deposited) and the lower part of the flat part 12 (the lower tangent part) is Δt1. This distance Δt1 corresponds to the thickness of the powder layer 31 to be formed next. The distance Δt1 is preferably several tens to 100 μm. The powder 20 located above the top surface level of the supply tank 21 is transferred and supplied to the modeling tank 22 by moving in the Y2 direction (towards the modeling tank 22) while rotating the flat portion 12 in the forward direction (direction of the arrow) (see Figure 2B). Furthermore, the flat portion 12 is moved parallel to the stage surface of the modeling stage 24 of the modeling tank 22, and a powder layer 31 having a predetermined thickness Δt1 is formed on the modeling layer 30 of the modeling stage 24 (flattening) (see FIG. 2C). After forming the powder layer 31, the flat portion 12 is moved in the Y1 direction and returned to its initial position. Here, the flat portion 12 is configured to be able to move while maintaining a constant distance from the top surface levels of the modeling tank 22 and the supply tank 21. By being able to move the flat portion 12 while maintaining a constant distance, the flat portion 12 can transport the powder 20 onto the modeling tank 22, and form a powder layer 31 of uniform thickness Δt1 on the modeling tank 22 or on an already formed modeling layer 30 (see FIG. 2D). Thereafter, droplets of the modeling liquid 10 are ejected from the head 52 of the modeling liquid applying means 5 to model the modeling layer 30 on the next powder layer 31 (modeling) (see FIG. 2E). Thereafter, the powder layer forming step and the modeling liquid applying step are repeated as many times as necessary to form a green body. Note that since the modeling tank 22 contains the powder 20, the green body is buried in the powder 20 in the modeling tank 22.

[0082] <Drying process and drying means> The drying step is a step of drying the green body in the modeling tank. The drying means is a means for drying the green body in the building tank. The green body is dried while being embedded in the powder in the molding tank. In the present invention, the green body obtained in the green body formation step is dried together with the shaping tank, which eliminates the step of removing the green body from the shaping tank. This reduces the number of steps required to manufacture a three-dimensional object, reduces the risk of damaging the green body, and improves the shaping quality. The drying means is not particularly limited as long as it can dry the entire modeling layer, and can be appropriately selected depending on the purpose. For example, known dryers and thermo-hygrostats are available.

[0083] <Pressing step and pressing means> The pressing step is a step of pressing the dried green body in the molding tank. The pressing step is a means for pressing the dried green body in the building tank. The green body is pressed while buried in the powder in the molding tank. In the present invention, by pressurizing the green body obtained in the drying step together with the modeling tank, the step of removing the green body from the modeling tank can be omitted. This means that the number of steps required to manufacture a three-dimensional object can be reduced, the risk of damaging the green body can be reduced, and the modeling quality can be improved. The pressing means is not particularly limited as long as it can pressurize the entire shaping layer, and can be appropriately selected depending on the purpose. For example, cold isostatic pressing (CIP) can be used.

[0084] The pressure in the pressurizing step is not particularly limited and can be appropriately selected depending on the purpose. For example, from the viewpoint of easily removing the green body from the molding tank and easily removing the powder adhering to the green body, it is preferable that the pressure is such that the powder in the molding tank does not solidify. More specifically, it is preferable that the pressure is 50 MPa or more and 200 MPa or less.

[0085] The pressing step is preferably carried out by a uniaxial pressing method, from the viewpoint that pressing can be performed with a simple device configuration and the cost of the device can be reduced. The pressing step is preferably carried out by a biaxial pressing method, from the viewpoint of being able to suppress uneven density at the upper and lower ends of the object to be pressed.

[0086] The drying and pressing steps are preferably performed while the green body obtained in the green body forming step remains embedded in the powder. This eliminates the need to remove the green body from the molding tank. This reduces the number of steps required to manufacture a three-dimensional object, reduces the risk of damaging the green body, and improves molding quality.

[0087] <Degreased Body Forming Step and Degreased Body Forming Means> The degreased body forming step is a step of forming a degreased body from the pressed green body. The degreased body forming means is a means for forming a degreased body from the pressed green body. In this specification, the term "degreased body" refers to a three-dimensional object obtained by degreasing organic components such as resin from a green body. In the degreased body forming step, the degreased body may be formed by heating the green body to remove the resin, or by immersing the green body in a solvent to extract the resin.

[0088] When the degreased body forming step is carried out by heating, the means for forming the degreased body is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include known sintering furnaces and electric furnaces.

[0089] When the degreased body forming process is carried out by heating, the degreased body forming means heats the green body for a certain period of time (e.g., 1 to 10 hours) at a temperature equal to or higher than the thermal decomposition temperature of the organic components such as resin and lower than the melting point or solidus temperature of the material constituting the metal particles (e.g., approximately 570°C when AlSi10Mg particles are used), thereby decomposing and removing the organic components.

[0090] <Sintered body forming step and sintered body forming means> The sintered body forming step is a step of heating the degreased body to form a sintered body. The sintered body forming means is a means for heating the degreased body to form a sintered body. In this specification, the term "sintered body" refers to a three-dimensional object formed by integrating metal material constituting metal particles as inorganic particles, and is formed by sintering a degreased body. The sintered body forming means is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include known sintering furnaces. The sintered body forming means may be the same as the means used when the degreased body forming means is performed by heating. Furthermore, the degreased body forming step and the sintered body forming step may be performed consecutively.

[0091] In the sintered body forming process, the degreased body is heated for a certain period of time (e.g., 1 to 10 hours) using a sintered body forming means at a temperature equal to or higher than the solidus temperature (e.g., approximately 570°C when AlSi10Mg particles are used) and lower than the liquidus temperature (e.g., approximately 600°C when AlSi10Mg particles are used) of the metal material that constitutes the metal particles as inorganic particles, thereby integrating the metal material that constitutes the metal particles.

[0092] <Other steps and other means> The other steps are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a powder removal step and a post-treatment step. The other means are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include powder removal means and post-processing means.

[0093] <<Powder Removal Step and Powder Removal Means>> The powder removing step is a step of removing the green body from the shaping tank after the pressing step and before the degreased body forming step, and removing the powder adhering to the green body. The powder removing means is a means for removing powder adhering to the green body. The removed powder becomes excess powder. The powder removal means is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include air blowing.

[0094] <<Post-processing step and post-processing means>> The post-treatment step is a step in which post-treatment is performed on the sintered body. The post-treatment step is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a surface protection treatment step and a painting step. The post-treatment means is a means for performing post-treatment on the sintered body. The post-treatment means is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include surface protection treatment means and painting means.

[0095] The surface protection treatment step is a step of forming a protective layer on the surface of the sintered body. By performing the surface protection treatment step, durability and the like can be imparted to the surface of the sintered body. Specific examples of the protective layer include a water-resistant layer, a weather-resistant layer, a light-resistant layer, a heat-insulating layer, and a glossy layer. Examples of the surface protection treatment means include known surface protection treatment devices, such as spray devices and coating devices.

[0096] The painting step is a step of painting the sintered body. By carrying out the painting step, the sintered body can be colored in a desired color. Examples of the coating means include known coating devices such as spray, roller, and brush coating devices.

[0097] Here, an embodiment of the method for manufacturing a three-dimensional object according to the present invention will be described with reference to the drawings. However, the use of the method for manufacturing a three-dimensional object according to the present invention is not limited to these embodiments.

[0098] FIG. 3 is a flowchart showing a method for manufacturing a three-dimensional object according to one embodiment of the present invention. First, as the green body forming process, a powder layer forming process is performed to form a powder layer containing powder (S1), and a modeling liquid applying process is performed to apply a modeling liquid to the powder layer. The powder layer forming process and the modeling liquid applying process are sequentially repeated to form the green body. Next, a drying step (S3) is performed to dry the green body obtained in the green body formation step. In the drying step, the green body is dried while it is placed in the modeling tank. A pressurizing step (S4) is performed to pressurize the dried green body. In the pressurizing step, the green body is pressed while it is placed in the modeling tank. The dried green body is removed from the modeling tank and a powder removal step (S5) is performed to remove powder adhering to the green body. A degreased body formation step (S6) is performed to form a degreased body from the green body from which the powder has been removed. Finally, a sintered body formation step (S7) is performed to heat the degreased body to form a sintered body. A three-dimensional object is manufactured through the above steps.

[0099] (Modeling system) The molding system of the present invention includes a green body forming means for forming a green body in a molding tank using powder, a drying means for drying the green body in the molding tank, a pressurizing means for pressurizing the dried green body in the molding tank, a degreased body forming means for forming a degreased body from the pressurized green body, and a sintered body forming means for heating the degreased body to form a sintered body, and may include other parts as necessary. Some of the devices in the modeling system of the present invention are the same as those already described, so duplicated descriptions will be omitted.

[0100] Here, an embodiment of the shaping system of the present invention will be described with reference to the drawings, but the use of the shaping system of the present invention is not limited to these embodiments.

[0101] FIG. 4 is a schematic explanatory diagram of a modeling system according to one embodiment of the present invention. The molding system 1000 includes a molding device 100 as a green body forming means, a drying device 200 as a drying means, a pressure applying device 300 as a pressure applying means, a powder removing device 400 as a powder removing means, and a sintering device 500 as a degreased body forming means and a sintered body forming means. The molding apparatus 100 molds a green body in a molding tank. The drying apparatus 200 dries the green body formed by the forming apparatus 100 together with the forming layer. The pressurizing device 300 pressurizes the green body dried in the drying device 200 together with the molding tank. The powder removal device 400 removes powder adhering to the green body pressed by the pressing device 300 . The sintering apparatus 500 degreases and sinters the green body from which the powder has been removed. The modeling system 100 may be composed of five separate devices: the modeling device 100, the drying device 200, the pressure device 300, the powder removal device 400, and the sintering device 500; the five devices may be integrated into a single device; or some of the functions may be installed in the modeling device 100 or the sintering device 500. [Example]

[0102] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following examples and comparative examples, unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass".

[0103] Example 1 A green body was formed using the molding apparatus shown in FIG. A powder layer was formed in the modeling tank using the powder layer forming means to an average thickness of 84 μm. Next, the modeling liquid was applied to the modeling area using the modeling liquid application means. By repeating these steps, a green body was formed in the modeling tank. The green body was buried in the powder in the modeling tank. Here, AlSi10Mg powder (Si10Mg-30BB, average particle size 35 μm, manufactured by Toyo Aluminum) was used as the powder. The modeling liquid used here was a resin dissolved in a solvent. Specifically, 88% by mass (total mass, not solid resin content) of partially saponified polyvinyl acetate resin (JMR-10LL, manufactured by Nippon Vinyl Acetate & Poval Co., Ltd.) was mixed with 12% by mass of triethylene glycol dimethyl ether, and the mixture was heated to 80°C and stirred for 2 hours using a magnetic stirrer to dissolve the resin. After stirring, the mixture was passed through a 1 μm filter to prepare the modeling liquid.

[0104] Next, the modeling tank was removed from the modeling apparatus, and the green body was dried while still submerged in the powder by heating (140°C, 8 hours) in a vacuum dryer (DP610P, Yamato Scientific) under reduced pressure. After drying, the green body was uniaxially pressed from above the powder layer in the building tank using a cold isostatic pressing (CIP) machine (manufactured by Nikkiso Co., Ltd.) at 150 MPa for 1 minute. Next, the green body was removed from the building tank and the powder was removed. The green body was then debound by heating in a small vacuum sintering furnace (manufactured by DOWA THERMOTECH) to form a debound body. The heating was performed using a small vacuum sintering furnace (manufactured by DOWA THERMOTECH) at a temperature above the thermal decomposition temperature of the resin but below the solidus temperature of the AlSi10Mg powder (approximately 300°C to 567°C). The resulting debound body was then subsequently held above the solidus temperature but below the liquidus temperature (567°C to 593°C) to form a sintered body.

[0105] Examples 2 to 12 The procedure was the same as in Example 1, except that the powder or pressing process was changed as shown in Table 1. The ceramic fillers used were alumina (ZWSK220 manufactured by Treibacher Schleifmittel), zirconia (YTZ-0.05 manufactured by Nikkato), and SiC (Silicon carbide manufactured by Sigma-Aldrich). The powder and filler were mixed using a bead mill (DYNO-MILL, manufactured by Shinmaru Enterprises Co., Ltd.).

[0106] (Comparative Example 1) In Comparative Example 1, after drying, the green body was removed from the modeling tank and placed in a flexible container together with powdered wax as a pressure medium, which was then vacuum-sealed. The container was then placed in a cold isostatic pressing (CIP) device and pressurized at 150 MPa for 1 minute. The other steps were the same as in Example 1.

[0107] (Comparative Example 2) Comparative Example 2 was the same as Example 1, except that the pressurizing step was not carried out.

[0108] (Comparative Example 3) After drying, the green body was removed from the build tank and placed in a flexible container with powdered wax as a pressure medium, which was then vacuum-sealed. The container was then placed in a cold isostatic pressing (CIP) device and pressurized at 150 MPa for 1 minute. The other steps were the same as in Example 6.

[0109] Next, productivity and quality were evaluated for each example and comparative example. Productivity was evaluated by man-hours. Quality was evaluated by the rate of breakage of the green body, powder removability, density, and deformation of the sintered body.

[0110] [Evaluation of man-hours] In each example and comparative example, the number of steps required from the time when drying was completed until the green body was introduced into the pressing device was judged based on the "criteria for judging the number of steps." The results are shown in Tables 1 and 2. -Effort criteria- ○: Less than 30 minutes ×: 30 minutes or more

[0111] [Damage rate of green body] In each example and comparative example, the percentage of breakage of the dried green body when it was introduced into the pressure device was visually confirmed and judged based on the "criteria for judging the percentage of breakage." Specifically, a plate-shaped (rectangular parallelepiped) sample was prepared, and if the plate cracked due to pressure, it was judged to be broken. The number of samples was 30. The results are shown in Tables 1 and 2. - Criteria for determining the damage ratio - ○: The number of damaged green bodies is less than 10% of the total. ×: The number of broken green bodies is 10% or more of the total.

[0112] [Powder removability] In each example and each comparative example, the powder removability of the green body after pressing was judged based on the "criteria for judging powder removability." The results are shown in Tables 1 and 2. - Criteria for powder removal performance - ○: All powder can be removed from the green body ×: Some of the powder adheres to the green body and cannot be removed.

[0113] [Density of the green body after pressing and density of the sintered body] In each example and comparative example, the density of the green body after pressing and the sintered body was measured by Archimedes' method. The results are shown in Tables 1 and 2. The details of the Archimedes' method are as follows. After measuring the weight A in air, we measured the weight B when submerged in a liquid with a density of ρ0. The density ρ of the object can be calculated using the following formula: ρ=A / (AB)ρ0 The liquid used in the measurements was pure water.

[0114] [Deformation amount of sintered body] FIG. 5 is a schematic diagram for explaining the amount of deformation of the sintered body in the example. In each example and comparative example, the green body E1 after pressing was formed to have a diameter of 30 mm and an average thickness of 3 mm. Both ends of the green body E1 were supported on alumina rods E3 (support distance: 15 mm), and the body was degreased and sintered. After sintering, the degree of deflection (deformation amount: Δh) at the center of the sintered body E2 caused by its own weight was measured using a dial gauge (ID-C125XB, manufactured by Mitutoyo). Ten samples were used, and the average value was used as the deformation amount. The results are shown in Tables 1 and 2.

[0115] [Table 1]

[0116] [Table 2]

[0117] From Examples 1 to 12, it can be seen that the green bodies were introduced into the pressure device without being removed from the building tank, which reduced the number of steps and reduced the rate of breakage of the green bodies. On the other hand, from Comparative Examples 1 and 3, it can be seen that the green bodies were removed from the building tank after drying, which increased the number of steps and increased the rate of breakage of the green bodies. Furthermore, in Comparative Examples 1 and 3, the rate of breakage of the green bodies was evaluated as "×", so no other evaluations were performed. Comparing Examples 1 to 12 with Comparative Example 2, it is found that the density of the green body is improved by performing the pressing step, and the density of the sintered body is also improved accordingly. Furthermore, it is found that the increased density of the green body also reduces the amount of deformation in the sintered body. In Example 5, the density unevenness in the powder layer was reduced by applying pressure using the biaxial pressure method, and therefore the green body density and the sintered body density were improved, and accordingly the effect of suppressing deformation in the sintered body was also improved. Examples 6 to 9 show that the deformation suppression effect in the sintered body is improved by adding 5 to 20 vol% of alumina powder as a ceramic filler, and Examples 10 and 11 show that the deformation suppression effect in the sintered body is improved by adding zirconia or silicon carbide as a ceramic filler. In Example 12, when alumina powder with an average particle size of approximately 100 nm was added as a ceramic filler, the density of the sintered body decreased and the deformation suppression effect of the sintered body was also inferior compared to Example 7. This is because the alumina powder had a small particle size and a strong adhesive force, which caused it to aggregate within the sintered body and inhibit sintering. In addition, the ability to support the sintered body was also reduced, suppressing the deformation suppression effect of the sintered body.

[0118] The present invention includes, for example, the following aspects. <1> a green body forming step of forming a green body in a building tank using the powder; a drying step of drying the green body in the building tank; a pressurizing step of pressurizing the dried green body in the building tank; a degreased body forming step of forming a degreased body from the pressed green body; and a sintered body forming step of heating the degreased body to form a sintered body. <2> The green body forming step forms a green body by repeating a powder layer forming step of forming a powder layer using the powder and a modeling liquid applying step of applying a modeling liquid to the powder layer. <1> 1. A method for producing a three-dimensional object according to claim 1. <3> The powder comprises pure aluminum or an aluminum alloy. <1> or <2> 1. A method for producing a three-dimensional object according to claim 1. <4> The powder contains a ceramic filler. <1> from <3> 10. A method for producing a three-dimensional object according to claim 9. <5> The ceramic filler is at least one selected from alumina, zirconia, and silicon carbide. <4> 1. A method for producing a three-dimensional object according to claim 1. <6> The average particle size of the ceramic filler is 20 μm or more. <4> or <5> 1. A method for producing a three-dimensional object according to claim 1. <7> The content of the ceramic filler is 5 vol% or more and 20 vol% or less with respect to the total amount of the powder. <4> from <6> 10. A method for producing a three-dimensional object according to claim 9. <8> the drying step and the pressing step are performed by burying the green body in the powder in the building tank. <1> from <7> 10. A method for producing a three-dimensional object according to claim 9. <9> The pressing step is performed at a pressure that does not cause the powder to solidify. <1> from <8> 10. A method for producing a three-dimensional object according to claim 9. <10> The pressure in the pressurizing step is 50 MPa or more and 200 MPa or less. <9> 1. A method for producing a three-dimensional object according to claim 1. <11> The pressing step is carried out by a uniaxial pressing method. <1> from <10> 10. A method for producing a three-dimensional object according to claim 9. <12> The pressurizing step is carried out by a biaxial pressurizing method. <1> from <10> 10. A method for producing a three-dimensional object according to claim 9. <13> a powder removing step of removing the green body from the shaping tank after the pressing step and before the degreased body forming step, and removing powder adhering to the green body. <1> from <12> 10. A method for producing a three-dimensional object according to claim 9. <14> a green body forming means for forming a green body in a building tank using powder; drying means for drying the green body in the building tank; a pressurizing means for pressurizing the green body in the shaping tank; a degreased body forming means for forming a degreased body from the green body; and a sintered body forming means for heating the degreased body to form a sintered body. <15> a green body forming means for forming a green body in a building tank using powder; drying means for drying the green body in the building tank; a pressurizing means for pressurizing the green body in the shaping tank; a degreased body forming means for forming a degreased body from the green body; and a sintered body forming means for heating the degreased body to form a sintered body.

[0119] <1> from <13> The method for producing a three-dimensional object according to any one of the above items. <14> The apparatus for manufacturing a three-dimensional object according to the present invention, <15> The molding system described in the above can solve the various problems in the prior art and achieve the object of the present invention. [Explanation of symbols]

[0120] 100 Modeling equipment 1 Powder layer forming means 11 Powder tank 12 Flat area 13 Powder removal section 16 stacked units 20 powder 21 Supply tank 22 Modeling tank 23 Supply Stage 24 Modeling Stage 25 Excess powder tank 30 Modeling layer 31 Powder layer 5 Modeling liquid application means 51 Carriage 52 heads [Prior art documents] [Patent documents]

[0121] [Patent Document 1] Japanese Patent Application Publication No. 2016-175202

Claims

1. a green body forming step of forming a green body in a building tank using the powder; a drying step of drying the green body in the building tank; a pressurizing step of pressurizing the dried green body in the building tank; a degreased body forming step of forming a degreased body from the pressed green body; and a sintered body forming step of heating the degreased body to form a sintered body.

2. 2. The method for manufacturing a three-dimensional object according to claim 1, wherein the green body forming step forms a green body by repeating a powder layer forming step of forming a powder layer using the powder and a modeling liquid applying step of applying a modeling liquid to the powder layer.

3. The method for manufacturing a three-dimensional object according to claim 1 or 2, wherein the powder contains pure aluminum or an aluminum alloy.

4. The method for manufacturing a three-dimensional object according to claim 1 or 2, wherein the powder contains a ceramic filler.

5. The method for manufacturing a three-dimensional object according to claim 4 , wherein the ceramic filler is at least one selected from the group consisting of alumina, zirconia, and silicon carbide.

6. The method for manufacturing a three-dimensional object according to claim 4 , wherein the ceramic filler has an average particle size of 20 μm or more.

7. The method for manufacturing a three-dimensional object according to claim 4 , wherein the content of the ceramic filler is 5 vol % or more and 20 vol % or less with respect to the total amount of the powder.

8. The method for manufacturing a three-dimensional object according to claim 1 or 2, wherein the drying step and the pressurizing step are performed by burying the green body in the powder in the manufacturing tank.

9. The method for manufacturing a three-dimensional object according to claim 1 or 2, wherein the pressurizing step applies a pressure that does not solidify the powder.

10. The method for manufacturing a three-dimensional object according to claim 9 , wherein the pressure in the pressurizing step is 50 MPa or more and 200 MPa or less.

11. The method for manufacturing a three-dimensional object according to claim 1 or 2, wherein the pressurizing step is performed by a uniaxial pressurizing method.

12. The method for manufacturing a three-dimensional object according to claim 1 or 2, wherein the pressurizing step is performed by a biaxial pressurizing method.

13. 3. The method for manufacturing a three-dimensional object according to claim 1, further comprising a powder removal step of removing the green body from the molding tank after the pressing step and before the degreased body forming step, and removing powder adhering to the green body.

14. a green body forming means for forming a green body in a building tank using the powder; drying means for drying the green body in the building tank; a pressurizing means for pressurizing the green body in the shaping tank; a degreased body forming means for forming a degreased body from the green body; and a sintered body forming means for heating the degreased body to form a sintered body.

15. a green body forming means for forming a green body in a building tank using the powder; drying means for drying the green body in the building tank; a pressurizing means for pressurizing the green body in the shaping tank; a degreased body forming means for forming a degreased body from the green body; and a sintered body forming means for heating the degreased body to form a sintered body.

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