Manufacturing method for three-dimensional formed article, forming device and forming system

Abstract

To provide a manufacturing method for a high-density, high-precision three-dimensional formed article.SOLUTION: A manufacturing method for a three-dimensional formed article includes: a forming step of forming a powder layer with a powder containing a ceramic material; an applying step of applying a liquid to the powder layer; and a heating step of heating the powder layer to which the liquid has been applied. The viscosity of a formed article obtained by repeating the forming step and the applying step one or more times is 1,000 Pa s or more and 100,000 Pa s or lower. In the heating step, the temperature of the powder layer to which the liquid has been applied is controlled to be 30°C or higher and 60°C or lower.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] 2. Description of the Related Art As one of the three-dimensional modeling methods, a binder jetting method is known in which a three-dimensional object is obtained by jetting a binder onto a material.

[0003] For example, Patent Document 1 discloses that, in order to obtain a dense three-dimensional object, fine powdered resin is granulated to form secondary particles, and then a solvent that dissolves the resin is applied.

[0004] However, the technique disclosed in Patent Document 1 has a problem in that it is difficult to manufacture a three-dimensional object with high density and high accuracy. Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a method for manufacturing a three-dimensional object with high density and high accuracy. [Means for solving the problem]

[0006] As a means for solving the above-mentioned problems, the method for manufacturing a three-dimensional object of the present invention includes a forming step of forming a powder layer with a powder containing a ceramic material, an applying step of applying a liquid to the powder layer, and a heating step of heating the powder layer to which the liquid has been applied, wherein the viscosity of the object obtained by repeating the forming step and the applying step one or more times is 1,000 Pa·s or more and 100,000 Pa·s or less, and the temperature of the powder layer to which the liquid has been applied is controlled in the heating step to be 30°C or more and 60°C or less. Effect of the Invention

[0007] According to the present invention, it is possible to provide a method for manufacturing a three-dimensional object with high density and high accuracy. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a conceptual diagram illustrating an example of a molding system according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a functional block diagram illustrating an example of a molding system according to an embodiment of the present invention. [Figure 3A] FIG. 2 is a schematic diagram for explaining an example of a powder containing a ceramic material according to one embodiment of the present invention. [Figure 3B] FIG. 1 is a schematic diagram for explaining an example of a method for producing a three-dimensional object according to an embodiment of the present invention (part 1). [Figure 3C] FIG. 2 is a schematic diagram for explaining an example of a method for producing a three-dimensional object according to one embodiment of the present invention (part 2). [Figure 4] 1 is a flowchart showing an example of a process flow in a manufacturing method of a three-dimensional object according to an embodiment of the present invention. [Diagram 5] FIG. 4 is a diagram illustrating a function of a control unit according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (Method of manufacturing three-dimensional objects) The method for producing a three-dimensional object of the present invention includes a forming step of forming a powder layer with a powder containing a ceramic material, an applying step of applying a liquid to the powder layer, and a heating step of heating the powder layer to which the liquid has been applied, wherein the viscosity of the object obtained by repeating the forming step and the applying step one or more times is 1,000 Pa s or more and 100,000 Pa s or less, and in the heating step, the temperature of the powder layer to which the liquid has been applied is controlled to 30°C or more and 60°C or less, and the method for producing a three-dimensional object includes other steps as necessary.

[0010] According to the present invention, by setting the viscosity of the object to a predetermined range, a three-dimensional object with high density and high accuracy can be obtained. The generation of viscosity facilitates mass transfer in a direction to fill voids present in the area where the liquid is applied, and a three-dimensional object with high density can be obtained. Furthermore, a relatively high viscosity state prevents the liquid from diffusing outside the area where the liquid is applied and also mitigates the tendency for the liquid to shrink, enabling stable modeling.

[0011] The area where the liquid is applied to the powder layer is a paste-like material that is a mixture of ceramic powder, solvent, resin, etc. The viscosity is determined by the combination of the material and the process. Therefore, even if the material is different, the viscosity can be adjusted to a specified range by adjusting the process. It is also possible to increase the density of the object and reduce the viscosity by applying vibrations to the object during the modeling process.

[0012] The viscosity of the molded object of the present invention is characterized by being 1,000 Pa·s or more and 100,000 Pa·s or less. In order to suppress warping of the three-dimensional object, the viscosity of the molded object is preferably 70,000 Pa·s or less, and more preferably 55,000 Pa·s or less. In order to mold a three-dimensional object with high precision, the viscosity of the molded object is preferably 5,000 Pa·s or more, more preferably 10,000 Pa·s or more, and even more preferably 20,000 Pa·s or more.

[0013] Here, the following definitions are used for terms used in the present invention. In the present invention, the term "in the process of forming" refers to a state in which a forming step and an applying step are repeatedly performed. The term "shaped object" refers to an object formed on the application part, which is obtained by repeatedly carrying out the forming step and the application step. The term "three-dimensional object" refers to an object that has been degreased and sintered, i.e., the state after all steps have been completed.

[0014] The method for producing a three-dimensional object of the present invention includes a forming step and an applying step, and further includes other steps as necessary. By repeating the forming step and the applying step a predetermined number of times, it is possible to obtain a high-density and high-precision object.

[0015] <Formation process> In the forming step, a powder layer is formed from powder containing a ceramic material. The powder is in the form of secondary particles containing primary particles.

[0016] -Primary particles- The main component of the primary particles in the present invention is ceramics, which means a sintered body obtained by heat-treating and baking an inorganic material. Here, the term "main component" means that the primary particles contain ceramics at more than 50 mass %, and the ceramic content in the primary particles is preferably 80 mass % or more, and more preferably 90 mass % or more. Examples of raw materials for ceramics include glass, metal oxides, metal carbides, and metal nitrides.

[0017] Examples of glass include silica glass (quartz glass) and soda-lime silica glass. Examples of metal oxides include zirconia, alumina, and mullite (aluminosilicate mineral). Examples of metal carbides include silicon carbide and tungsten carbide. Examples of metal nitrides include silicon nitride and aluminum nitride. The ceramics may be used alone or in combination of two or more. Among these, from the viewpoint of maintaining high strength, zirconia, alumina, mullite (aluminosilicate mineral), tungsten carbide, silicon carbide, silicon nitride, and aluminum nitride are preferred. The particle size of the primary particles is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 2 μm or less. A particle size of 10 μm or less is preferable in that sintering easily proceeds.

[0018] -Secondary particles- The powder for three-dimensional modeling is obtained by producing secondary particles from the primary particles. Since the primary particles have a small particle size, they have low fluidity and are difficult to handle, but by making the secondary particles contain a binder resin, they become easier to handle.

[0019] The method for producing the secondary particles is not particularly limited and can be appropriately selected depending on the purpose. For example, a method of mixing a binder resin with the primary particles according to a known method can be mentioned. The method for granulating the primary particles with a binder resin is not particularly limited and can be appropriately selected from known granulation methods, such as a rolling fluidization method, a spray drying method, an agitation granulation method, a dipping method, and a kneader coating method. These granulation methods can be carried out using various known commercially available coating devices and granulation devices. More specifically, the primary particles and the binder resin may be mixed together in a solvent and thoroughly dispersed to prepare a slurry, which may then be dried and pulverized to obtain secondary particles.

[0020] -Binding resin- The binder resin contained in the secondary particles contributes to, for example, binding between primary particles and binding again to surrounding ceramic particles after dissolving when the liquid is dropped. The type of binder resin is not particularly limited and can be appropriately selected according to the purpose.The binder resin is preferably a thermoplastic resin, and examples thereof include acrylic, maleic acid, silicone, butyral, polyester, polyvinyl acetate, vinyl chloride / vinyl acetate copolymer, polyethylene, polypropylene, polyacetal, ethylene / vinyl acetate copolymer, ethylene / (meth)acrylic acid copolymer, α-olefin / maleic anhydride copolymer, esterified product of α-olefin / maleic anhydride copolymer, acrylic polyol, polystyrene, poly(meth)acrylic acid ester, α-olefin / maleic anhydride / vinyl group-containing monomer copolymer, styrene / maleic anhydride copolymer, styrene / (meth)acrylic acid ester copolymer, polyamide, epoxy resin, xylene resin, ketone resin, petroleum resin, rosin or its derivative, coumarone-indene resin, terpene resin, polyurethane resin, synthetic rubber such as styrene / butadiene rubber, polyvinyl butyral, nitrile rubber, acrylic rubber, ethylene / propylene rubber, and nitrocellulose. Among these, polyvinyl butyral, polyvinyl acetate, and acrylic polyol are preferred from the viewpoints of ease of degreasing and adhesion to ceramics. These may be used alone or in combination of two or more.

[0021] The content of the binder resin in the secondary particles is not particularly limited and can be appropriately selected depending on the purpose, but from the viewpoint of preventing cracks, defect formation, and deformation of the three-dimensional object, it is preferably 25% by mass or less, more preferably 20% by mass or less, even more preferably 15% by mass or less, and particularly preferably 10% by mass or less. Also, from the viewpoint of the strength of the object, the lower limit of the content of the binder resin is preferably 1% by mass or more, more preferably 3% by mass or more.

[0022] <Application process> In the application process, a liquid is applied to the powder layer formed in the formation process. This dissolves the binder resin contained in the secondary particles, turning the secondary particles into primary particles, and the primary particles fill the gaps formed between the secondary particles. As a result, the area where the liquid is applied to the powder layer is fixed by the binder resin, and the shape of the secondary particles is distorted, making the area where the liquid is applied homogenized, and the area where the liquid is applied can have fewer gaps and unsolidified areas. In addition, the ends of the area where the liquid is applied can reduce unevenness in the planar direction caused by the secondary particles, making it possible to achieve high-precision modeling.

[0023] The application step is not particularly limited as long as it is a step of applying a liquid that dissolves the binder resin contained in the secondary particles to a predetermined area, and can be appropriately selected depending on the purpose. The area to which the liquid is applied may be a part or the entire powder layer. In addition, it is preferable that the amount of the liquid applied can be adjusted. Examples of methods for applying liquid to a predetermined area include a dispenser method, a spray method, and an inkjet method, with the inkjet method being particularly preferred. The inkjet method has the advantage of being able to apply droplets more quantitatively than the spray method and being able to apply a larger area than the dispenser method, making it possible to form complex shapes with high precision and high efficiency. In the case of the inkjet method, the application unit has a nozzle capable of applying the liquid to a predetermined area. As the nozzle, a nozzle (ejection head) in a known inkjet printer can be suitably used. In addition, by controlling the amount of liquid applied by each of the multiple nozzles, the amount or area of ​​the liquid applied to the powder layer can be adjusted.

[0024] <<Liquid>> There are no particular limitations on the liquid, so long as it is capable of dissolving the binder resin of the secondary particles, and the liquid can be appropriately selected depending on the purpose. The liquid contains a solvent and, if necessary, further contains other components.

[0025] -solvent- The solvent is not particularly limited as long as it can dissolve the binder resin of the secondary particles, and can be appropriately selected according to the purpose, but is preferably an organic solvent. The organic solvent must have a high boiling point to perform stable application, and the boiling point of the organic solvent is preferably 75°C or higher, more preferably 100°C or higher, and even more preferably 150°C or higher. The organic solvent is preferably dimethyl sulfoxide (DMSO), diacetone alcohol (DAA), or ethyl acetate. These may be used alone or in combination of two or more.

[0026] The content of the solvent in the liquid is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 90% by mass or more, more preferably 95% by mass or more, and particularly preferably 100% by mass.

[0027] -Other ingredients- The other components are not particularly limited and can be appropriately selected according to the purpose, and examples thereof include dispersants, surfactants, resins, and inorganic particles. By containing inorganic particles, the density of the three-dimensional object can be improved. When the liquid contains other components, the lower limit of the content of the solvent in the liquid is preferably 30% by mass or more, more preferably 40% by mass or more, and the upper limit of the content of the solvent in the liquid is preferably 95% by mass or less, more preferably 90% by mass or less.

[0028] <Heating process> In the heating step, the powder layer to which the liquid has been applied is heated. The heating unit is not particularly limited, and examples thereof include an IR heater and a ceramic heater. The timing of heating is preferably when the liquid is not being applied in the application unit, such as immediately after the application step is completed or during the formation step. In particular, if heating is performed immediately after the liquid is applied to the powder layer in the application step, the liquid dissolves the binder resin due to heating, the viscoelasticity becomes a predetermined state, and the three-dimensional object has a high density and high accuracy, which is preferable. In the heating step, heating is performed for a certain period of time before the formation step begins, and the heating step is completed when the predetermined temperature is maintained for a certain period of time. For example, it is preferable to heat for about 5 to 30 seconds immediately after the liquid hits the powder layer. The heating unit preferably also has a cooling function to control the temperature of the powder layer to which the liquid has been applied. An example of the cooling function is a blower fan. This controls the temperature of the powder layer to 30° C. or higher and 60° C. or lower. By controlling the temperature of the powder layer within the above range, the viscosity of the model in the powder layer can be controlled.

[0029] <Other processes> The other steps are not particularly limited and can be appropriately selected depending on the purpose. Examples of the other steps include a vibration step, a measuring step, a drying step, a degreasing step, and a sintering step.

[0030] In the vibration process, the powder layer is vibrated to increase the density of the molded object and thereby reduce the viscosity of the molded object. The vibration applied to the powder layer preferably has an amplitude of 0.1 mm and a frequency of 1 kHz, but is not limited thereto.

[0031] In the measurement process, the viscosity of the object being modeled is measured. Each time the forming process and the applying process are repeated, the viscosity of the surface of the object being modeled is measured. By performing the measurement process, it is possible to confirm the change in the viscosity of the object being modeled over time. In addition, the amount or area of ​​the liquid applied in the next repeated applying process can be adjusted so that the measured viscosity becomes a specified value. As a means for measuring the viscosity of the object being modeled, non-contact measurements such as measurements using low-frequency sound waves and a laser displacement meter or the DWS method in which a sample is irradiated with laser light and the vibration of the intensity of the reflected scattered light is evaluated are preferable, but a direct method in which the object being modeled is removed with tweezers or the like and measured using a rheometer can also be used.

[0032] In the drying step, the organic solvent is removed from the shaped object. The drying step can be performed for each layer after the forming step and the applying step using an infrared heater, etc. There is no particular limitation on the drying method, and any known method can be used, but it is necessary to select a method that does not cause cracking or deformation depending on the type of solvent. For example, when ethanol is used as the solvent, it is preferable to perform drying at 50°C for 24 hours.

[0033] In the degreasing step, the shaped object dried in the drying step is degreased. The degreasing method is not particularly limited, and any well-known method can be used. For example, when alumina is used as the primary particles, the degreasing can be suitably performed by heat treatment at 500°C for 3 hours in a nitrogen-substituted environment, but the method is not limited thereto.

[0034] In the sintering step, the shaped object degreased in the degreasing step is sintered. There is no particular restriction on the sintering method, and any known method can be used, but in order to maximize the effects of the present invention, it is preferable to sinter under normal pressure. The atmosphere, heat treatment temperature, and heat treatment time must be adjusted depending on the material. For example, when alumina is used as the primary particles, heat treatment at 1,550°C for 3 hours in an argon atmosphere is preferable. It is possible to increase the density by increasing the heat treatment temperature, but there are also disadvantages such as reduced strength and deformation due to the formation of coarse particles, so optimization of the conditions is required. As a sintering method, for example, in the case of a graphite mold, a current sintering method using pulse current heating or the like can be suitably used, but the sintering method is not limited to this.

[0035] It is possible to carry out a drying process, a degreasing process, and a sintering process according to the molding material, but since the molded object generally has a characteristic shape, a pressurizing means is often not used to prevent the object from collapsing. In particular, in the sintering process, pressure sintering (hot pressing) is often performed to improve the sintered density, but in the present invention, hot pressing is not used and normal pressure sintering is basically used. In the present invention, in the method for producing a three-dimensional ceramic object, the raw materials of the three-dimensional ceramic object are temporarily bound together, and then the three-dimensional ceramic object is obtained. In this case, even if a resin is used for binding, the amount of the resin used for binding is small, so that the volume shrinkage after sintering is small. As a result, even when a large structural member is manufactured, cracks during sintering can be prevented, and a model with dimensions that can be used as a structural member can be manufactured.

[0036] The object formed by repeating the forming step and the applying step is embedded in the powder, and the three-dimensional modeling ends. At this stage, the molded object contains a large amount of solvent, making it weak and difficult to handle, and so drying is required. The drying method is not particularly limited, and any known method can be used. However, it is necessary to select a method that does not cause cracking or deformation depending on the type of solvent. For example, when ethanol is used as the solvent, it is preferable to dry at 50° C. for 24 hours.

[0037] (3D model) The three-dimensional object of the present invention is produced by the method for producing a three-dimensional object of the present invention.

[0038] The uses of the three-dimensional objects are not particularly limited and can be appropriately selected depending on the purpose. For example, they can be suitably used for meters and operation panels of automobiles, office automation equipment, electric and electronic devices, cameras, various parts, daily necessities, prototypes, etc.

[0039] Here, an example of a method for manufacturing a three-dimensional object and a modeling apparatus according to the present invention will be described with reference to the drawings.

[0040] FIG. 1 is a conceptual diagram showing an example of a method for producing a three-dimensional object according to an embodiment of the present invention.

[0041] FIG. 2 is a functional block diagram illustrating an example of a modeling system according to an embodiment of the present invention. The modeling system 100 includes a computer 101 , a modeling apparatus 102 , a drying apparatus 103 , a degreasing apparatus 104 , and a sintering apparatus 105 . The molding apparatus 102 has a forming unit 1, an applying unit 2, a heating unit 3, a vibration applying unit 4, a measuring unit 5, and a control unit 6. The drying apparatus 103 has a drying unit 7. The degreasing apparatus 104 has a degreasing unit 8. The sintering apparatus 105 has a sintering unit 9.

[0042] The computer 101 transmits 3D data of a three-dimensional object to be modeled to the modeling apparatus 102 .

[0043] The modeling apparatus 102 models a modeled object based on 3D data. The modeling of the modeled object is performed through a forming process by a forming unit 1, an imparting process by an imparting unit 2, a heating process by a heating unit 3, a vibration process by a vibration imparting unit 4, and a measurement process by a measuring unit 5.

[0044] The forming part 1 performs a forming step of forming a powder layer with a powder containing a ceramic material. FIG. 3A is a schematic diagram for explaining an example of a powder containing a ceramic material according to an embodiment of the present invention. As the powder containing a ceramic material used for forming the forming part 1, primary particles and a binder resin are used to granulate secondary particles. These secondary particles are used to form the forming part 1. For example, the primary particles containing the ceramic material and the binder resin are mixed together in a solvent and thoroughly dispersed to prepare a slurry. The slurry is then dried and pulverized to form secondary particles. The secondary particles have a three-dimensional structure in which fine primary particles are bonded to each other and have gaps, and are approximately spherical in shape. 3B is a schematic diagram for explaining an example of a manufacturing method of a three-dimensional object according to an embodiment of the present invention. The modeling apparatus 102 includes a stage 50, a supply-side powder storage tank 52, a stage 53, a modeling-side powder storage tank 54, and a flattening means 55 as a forming unit 1. The supply-side powder storage tank 52 stores the powder 51. The supply-side powder storage tank 52 has a stage 50 that can be raised and lowered. The manufacturing-side powder storage tank 54 forms a powder layer. The manufacturing-side powder storage tank 54 has a stage 53 that can be raised and lowered. When a roller, for example, as the flattening means 55, moves from the supply-side powder storage tank 52 to the manufacturing-side powder storage tank 54, the powder 51 in the supply-side powder storage tank 52 moves to the manufacturing-side powder storage tank 54. As a result, a powder layer of the powder 51 is formed on the stage 53. There is no particular restriction on the average thickness of the powder layer, and it can be appropriately selected depending on the purpose, but the average thickness per layer is preferably 10 μm to 200 μm, more preferably 30 μm to 100 μm.

[0045] The applying unit 2 performs an applying step of applying a liquid to the powder layer formed in the forming unit 1. As a result, the binder resin contained in the powder 51 is dissolved. 3C is a schematic diagram for explaining an example of a method for manufacturing a three-dimensional object according to an embodiment of the present invention. An example is shown in which an inkjet head 57 is used as the application unit 2. The inkjet head 57 is used to apply liquid 58 to the powder layer 56. This dissolves the binder resin, and the primary particles fill the voids formed between the secondary particles. As a result, the region to which the liquid 58 is applied is fixed by the binder resin, and the shape of the secondary particles is distorted, so that the region to which the liquid 58 is applied is homogenized, and the region to which the liquid 58 is applied can have fewer voids and unsolidified regions. The application unit 2 can also adjust the amount and area to which the liquid 58 is applied. Specifically, the application unit 2 may control the amount of liquid 58 applied by each of the multiple inkjet heads 57 in response to an instruction from the control unit 6. This makes it possible to adjust the viscosity of the object being modeled.

[0046] The heating unit 3 performs a heating step of heating the powder layer 56 to which the liquid 58 has been applied in the application unit 2 . The heating unit 3 preferably also has a cooling function in order to control the temperature of the powder layer 56 to which the liquid 58 has been applied at a predetermined temperature. The heating unit 3 may control the viscosity of the powder layer 56 by, for example, setting the temperature of the powder layer 56 to 30° C. or more and 60° C. or less in accordance with an instruction from the control unit 6. As the heating unit 3, as shown in FIG. 3B, it is preferable to control the temperature of the powder layer 56 by heating the powder layer 56 or the entire inside of the modeling apparatus using, for example, an infrared heater or a ceramic heater, but this is not limited thereto.

[0047] The vibration applying unit 4 performs a vibration step of applying vibration to the powder layer 56. The vibration applying unit 4 can be provided, for example, below the stage 53 as shown in FIG. 3B, but is not limited to this. By applying vibration to the powder layer 56 to which the liquid 58 has been applied, the density of the powder layer 56 can be increased and the viscosity of the powder layer 56 can be reduced. The amplitude and frequency of the vibration applied to the powder layer 56 by the vibration applying unit 4 may be controlled by the control unit 6.

[0048] The measuring unit 5 performs a measuring process of measuring the viscosity of the object being modeled in a non-contact manner. The measuring unit 5 can be attached to the side of the inkjet head 57 as shown in Fig. 3C, for example, but is not limited to this.

[0049] The control unit 6 controls the operation of each unit including the applying unit 2 and the heating unit 3. The control unit 6 may be, for example, a calculation processing device such as a CPU (Central Processing Unit). The control unit 6 can adjust the amount or area of ​​the liquid 58 applied in the next applying step and the temperature of the powder layer so that the viscosity measured in the measurement step becomes a predetermined value. The viscosity of the molded object is correlated with the amount of the liquid 58 applied, and the viscosity is low when the amount of liquid is large, and the viscosity is high when the amount of liquid is small. The viscosity of the molded object is also correlated with the temperature of the powder layer, and the viscosity is low when the temperature is high, and the viscosity is high when the temperature is low. The viscosity of the molded object responds sensitively to the amount of liquid and responds slowly to the temperature. By utilizing this difference in responsiveness, it is possible to quickly adjust the viscosity to the target viscosity by responding with the temperature when the measurement result changes slowly, and by responding with the amount of liquid when the measurement result changes rapidly. The control unit 6 may be provided in the computer 101 .

[0050] The drying unit 7 performs a drying step to remove the organic solvent from the shaped object. The drying step can be performed for each layer after the forming step and the applying step using an infrared heater or the like. There is no particular limitation on the drying method, and any known method can be used, but it is necessary to select a method that does not cause cracking or deformation depending on the type of solvent. For example, when ethanol is used as the solvent, it is preferable to perform drying at 50°C for 24 hours.

[0051] The degreasing unit 8 performs a degreasing step of degreasing the shaped object dried in the drying step. There is no particular limitation on the degreasing method, and any well-known method can be used. For example, when alumina is used as the primary particles, the degreasing can be suitably performed by performing a heat treatment at 500°C for 3 hours in a nitrogen-substituted environment, but the method is not limited thereto.

[0052] The sintering unit 9 performs a sintering step of sintering the shaped object degreased in the degreasing step, thereby obtaining a three-dimensional shaped object.

[0053] 4 is a flow chart showing an example of a process flow in a method for manufacturing a three-dimensional object according to one embodiment of the present invention. The process flow in the method for manufacturing a three-dimensional object according to the present invention will be described. Note that descriptions of points that overlap with the contents described in FIGS. 2 to 3C will be omitted as appropriate.

[0054] In step S1, when the user inputs the number of repetitions to the molding apparatus 102, the process proceeds to S2.

[0055] In step S2, when the user inputs k=0 to the modeling apparatus 102, the process proceeds to S3.

[0056] In step S3, the forming unit 1 performs a forming step of forming the powder layer 56, and then the process proceeds to S4.

[0057] In step S4, the application unit 2 performs an application step of applying liquid 58 to the powder layer 56, and then the process proceeds to S5.

[0058] In step S5, the heating unit 3 performs a heating step of heating the powder layer 56, and then the process proceeds to S6.

[0059] In step S6, the vibration applying unit 4 performs a vibration step of applying vibration to the powder layer 56, and then the process proceeds to S7.

[0060] In step S7, the measuring unit 5 performs a measurement process of measuring the viscosity of the molded object, and then the process proceeds to S8. Based on the result of the measurement in the measurement process, the molding device 102 adjusts the amount or area to which the liquid 58 is applied, and the temperature of the powder layer 56, so that the viscosity becomes a predetermined value. As a means for measuring the viscosity of the molded object during molding, a non-contact measurement such as a measurement using a low-frequency sound wave and a laser displacement meter or a DWS method in which a laser beam is irradiated onto a sample and the vibration of the intensity of the reflected and scattered light is evaluated is preferable. The amount or area of ​​the applied liquid 58 and the temperature of the powder layer 56 may be adjusted using a trained model based on machine learning. The details of the adjustment using the trained model will be described later.

[0061] In step S8, when k+1=k is input, the process proceeds to S9.

[0062] In step S9, if the control section 6 determines that k is smaller than the number of repetitions, it shifts the process to S3, and if it determines that k is equal to or greater than the number of repetitions, it shifts the process to S10. The forming step, the applying step, the heating step, the vibrating step, and the measuring step are repeated until a desired number of layers is reached, thereby obtaining a shaped object on the stage 53.

[0063] In step S10, the drying unit 7 performs the drying process, and then the process proceeds to S11.

[0064] In step S11, the degreasing unit 8 performs the degreasing process, and then the process proceeds to S12.

[0065] In step S12, the sintering unit 9 performs a sintering process, whereby the entire process is completed and a three-dimensional object is obtained.

[0066] Now, with reference to FIG. 5, adjustment of the amount or area of ​​applied liquid 58 and the temperature of powder layer 56 by control unit 6 will be described.

[0067] The control unit 6 in this embodiment may estimate the amount or area of ​​the liquid 58 and the temperature of the powder layer 56 that will make the viscosity of the modeled object a predetermined value, using the trained model. In this case, in the modeling apparatus 102, the control unit 6 controls the application unit 2 in accordance with the estimation result using the trained model, thereby adjusting the amount or area of ​​the liquid 58 so that the viscosity of the modeled object becomes the predetermined value. Also, in the modeling apparatus 102, the control unit 6 controls the heating unit 3 in accordance with the estimation result using the trained model, thereby adjusting the temperature of the powder layer 56 so that the viscosity of the modeled object becomes the predetermined value.

[0068] 5 is a diagram illustrating functions of a control unit according to an embodiment of the present invention. The control unit 6 of this embodiment has a data accumulation unit 85, a learning unit 86, and an estimation unit 87. The functions of the data accumulation unit 85, the learning unit 86, and the estimation unit 87 may be realized by a machine learning program implemented in the control unit 6.

[0069] The data accumulation unit 85 accumulates data including modeling conditions including at least one of the amount or area of ​​the liquid 58 applied by the application unit 2, and the temperature of the powder layer 56. Note that the data accumulation unit 85 may accumulate data indicating the viscosity of the modeled object measured by the measurement unit 5 together with the data on the modeling conditions, etc.

[0070] The learning unit 86 extracts feature amounts based on the data stored in the data storage unit 85, and learns the relationship between the viscosity of the object and the modeling conditions based on the feature amounts. The learning unit 86 may, for example, use a data set that associates the modeling conditions stored in the data accumulation unit 85 with the viscosity of the modeled object measured by the measurement unit 5 as teacher data to generate a trained model 88 that has learned the relationship between the modeling conditions and the viscosity of the modeled object, and cause the trained model 88 to be stored in the estimation unit 87. When a value indicating the viscosity of the modeled object is input, for example, the trained model 88 may estimate modeling conditions under which the viscosity of the modeled object becomes the input value. The algorithm used by the learning unit 86 is not particularly limited, and deep learning using a neural network, an unsupervised learning model, a supervised learning model, a reinforcement learning model, etc. can be applied.

[0071] The estimation unit 87 estimates modeling conditions corresponding to the input viscosity of the object based on the learning by the learning unit 86. For example, when a value indicating the viscosity of the object is input, the estimation unit 87 inputs the input value to the trained model 88 and estimates modeling conditions to be output from the trained model 88.

[0072] The control unit 6 controls the applying unit 2 or the heating unit 3 based on the modeling conditions estimated by the estimation unit 87. The control unit 6 controls the applying unit 2 and the heating unit 3 based on, for example, the amount or area of ​​the liquid 58 to be applied and the temperature of the powder layer 56, which are included in the modeling conditions estimated by the estimation unit 87.

[0073] In this embodiment, by doing so, the amount or area of ​​the applied liquid 58 and the temperature of the powder layer 56 can be adjusted using a machine learning trained model. EXAMPLES

[0074] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0075] A three-dimensional object was manufactured according to the manufacturing method of the three-dimensional object shown in Figures 3A to 3C and the flowchart shown in Figure 4. The powders and organic solvents used in each of the examples and comparative examples are shown in Table 1.

[0076] First, a powder was prepared. Example 1 <Preparation of Primary and Secondary Particles> First, primary particles (alumina: high purity alumina AHP200, manufactured by Nippon Light Metal Co., Ltd.) of 0.4 μm and binder resin (polyvinyl butyral (PVB): manufactured by Kuraray Co., Ltd., Mobital B30) of 10 wt % shown in Table 1 were mixed together in a solvent (methyl ethyl ketone: manufactured by Sankyo Chemical Co., Ltd.) and thoroughly dispersed to prepare a slurry. The slurry was then dried and pulverized to obtain secondary particles with a median particle size of 20 μm. The secondary particles have a three-dimensional structure in which fine primary particles are bonded to each other and have gaps between them, forming approximately spherical secondary particles. The median particle sizes of the primary particles and the secondary particles were measured as follows.

[0077] -Measurement of median particle size of primary and secondary particles- The median particle size of the primary particles and secondary particles is the cumulative 50% particle size (D50) based on the volume-based particle size distribution measured for each particle using a laser diffraction / scattering particle size analyzer (LA-300, manufactured by Horiba, Ltd.).

[0078] <Modeling> The molding was performed using a binder jet molding device (Desktopmetal) and a simplified prototype that was partially solvent-compatible. In this example, printing was performed at 600 DPI, and the layer thickness was 100 μm. In addition, three cubes measuring 10 mm x 10 mm x 10 mm and three flat plates measuring 40 mm x 40 mm x 1 mm were molded as molded objects. One of the cubes was removed immediately after molding, and the viscosity was measured. The remaining two cubes were dried at 50° C. for 24 hours together with the three flat plates.

[0079] <Amount of liquid (organic solvent) applied> DMSO (StG grade, manufactured by Toray Fine Chemicals Co., Ltd.) was used as the liquid (organic solvent) and the amount of the applied liquid was 50 Voxel%. A voxel is a unit volume in the three-dimensional modeling method, Voxel[L]=1 / (DPI / 2.54)*1 / (DPI / 2.54)*t It is calculated as follows, where t is the layer thickness. The volume of the ejected liquid [L] can be calculated from the weight of any number of droplets ejected and the density of the liquid. The amount applied (Voxel%) can be calculated by the amount of liquid ejected [L] / Voxel [L].

[0080] <Powder surface temperature> The powder surface temperature in the heating section was 30° C. Here, the powder surface temperature is the temperature of a part of the powder layer formed by the forming section or a region where the liquid is applied to the powder layer by the application section.

[0081] <Debinding and sintering> Debinding and sintering were performed in an electric furnace by increasing the temperature to each of the designated temperatures from 1,100°C to 1,500°C at a rate of 5°C / min, holding each temperature for 2 hours, and then cooling the furnace to obtain a three-dimensional object.

[0082] Example 2 In Example 2, a molded object and a three-dimensional molded object were obtained in the same manner as in Example 1, except that the powder surface temperature was changed from 30°C to 60°C.

[0083] Example 3 In Example 3, a shaped object and a three-dimensional shaped object were obtained in the same manner as in Example 1, except that the primary particle size was changed from 0.4 μm to 2.1 μm and the powder surface temperature was changed from 30° C. to 50° C.

[0084] Example 4 In Example 4, a shaped object and a three-dimensional shaped object were obtained in the same manner as in Example 1, except that the primary particle size was changed from 0.4 μm to 2.1 μm.

[0085] Example 5 In Example 5, a molded object and a three-dimensional molded object were obtained in the same manner as in Example 3, except that the amount of binder resin was changed from 10 wt % to 5 wt % and the powder surface temperature was changed from 50°C to 60°C.

[0086] Example 6 In Example 6, a shaped object and a three-dimensional shaped object were obtained in the same manner as in Example 3, except that the amount of binder resin was changed from 10 wt % to 5 wt %, and the type of organic solvent was changed from DMSO to DAA.

[0087] Example 7 In Example 7, a shaped object and a three-dimensional shaped object were obtained in the same manner as in Example 6, except that the type of organic solvent was changed from DAA to ethyl acetate (manufactured by Hayashi Pure Chemical Industries, Ltd., special grade ≧99.5%).

[0088] Example 8 In Example 8, a molded object and a three-dimensional molded object were obtained in the same manner as in Example 3, except that the amount of binder resin was changed from 10 wt % to 8 wt %, and the amount of organic solvent was changed from 50 voxel % to 51 voxel %.

[0089] Example 9 In Example 9, a shaped object and a three-dimensional shaped object were obtained in the same manner as in Example 8, except that the amount of binder resin was changed from 8 wt % to 5 wt %.

[0090] Example 10 In Example 10, a shaped object and a three-dimensional shaped object were obtained in the same manner as in Example 8, except that the amount of binder resin was changed from 8 wt % to 4 wt %.

[0091] Example 11 In Example 11, a shaped object and a three-dimensional shaped object were obtained in the same manner as in Example 9, except that the primary particle size was changed from 2.1 μm to 0.4 μm and the amount of organic solvent was changed from 51 voxel % to 55 voxel %.

[0092] Example 12 In Example 12, a shaped object and a three-dimensional shaped object were obtained in the same manner as in Example 11, except that the amount of the organic solvent was changed from 55 voxel % to 60 voxel %.

[0093] (Example 13) In Example 13, a shaped object and a three-dimensional shaped object were obtained in the same manner as in Example 11, except that the amount of the organic solvent was changed from 55 voxel % to 65 voxel %.

[0094] (Comparative Examples 1 to 16) In Comparative Examples 1 to 16, the primary particle diameter, binder resin amount, organic solvent, and powder surface temperature were changed to those shown in Table 1, and shaped objects and three-dimensional shaped objects were obtained.

[0095] The measurement results for the three-dimensional objects obtained in each of the Examples and Comparative Examples are shown in Table 2.

[0096] <Viscosity measurement> Using one of the cubic objects, the viscosity of the surface of the object was measured in accordance with ISO6721-10. A rheometer (MCR302, manufactured by Anton Paar Japan Co., Ltd.) was used to measure the viscosity. The viscosity was measured under the following conditions: method: shear viscosity, plate: PP20, gap: 0.1 mm, temperature: 25°C, frequency: 1 Hz. The viscosity at a strain of 0.1% was adopted as it is considered to be close to the state of the object during printing.

[0097] <Can three-dimensional objects be created?> The feasibility of creating a three-dimensional object was judged based on the following criteria. [Evaluation Criteria] Y: The modeling was successful. N1: The print failed due to the excessive warping of the print and contact with the recoater. N2: The model failed due to the model becoming too thick and coming into contact with the recoater. N3: The print failed due to cracks.

[0098] <Filling rate> The density of the cubic three-dimensional object was measured by the Archimedes method, and the packing ratio was calculated.

[0099] <Warpage and center thickness> The amount of warping and the central thickness of the plate were measured using a height gauge.

[0100] [Table 1]

[0101] [Table 2] In Comparative Examples 3, 8, 9, and 10, the molded objects maintained a powdery state and did not exhibit viscosity, so the viscosity could not be measured. Also, "-" in Table 2 indicates that molding was unsuccessful and therefore there were no measurement results.

[0102] When the amount of organic solvent was small (Comparative Example 3) or when a material with a large particle size was used (Comparative Example 9), the model maintained a powdery state so that it did not show any viscosity, resulting in a low-density model. When the viscosity was too low (Comparative Examples 5, 7, 11, 13, and 16), the model became thicker than the printed area and could come into contact with the recoater during printing. This proves that when the viscosity exceeds a certain value, mass transfer occurs and voids become more easily filled. Furthermore, when the viscosity is too high (Comparative Examples 1 and 4), the model warped significantly and could come into contact with the recoater during printing. Therefore, there is an appropriate range for the viscosity of the model.

[0103] For example, aspects of the present invention are as follows. <1> A method for manufacturing a three-dimensional object, comprising: a forming step of forming a powder layer with a powder containing a ceramic material; an applying step of applying a liquid to the powder layer; and a heating step of heating the powder layer to which the liquid has been applied, wherein the viscosity of the object obtained by repeating the forming step and the applying step one or more times is 1,000 Pa s or more and 100,000 Pa s or less; and in the heating step, the temperature of the powder layer to which the liquid has been applied is controlled to 30°C or more and 60°C or less. <2> a measuring step of measuring a viscosity of the object after the heating step, and adjusting an amount or an area to which the liquid is applied so that the viscosity becomes a predetermined value. <1> 2. A method for producing a three-dimensional object according to claim 1 . <3> The method further comprises a vibration step of applying vibration to the shaped object after the heating step. <1> from <2> 10. A method for producing a three-dimensional object according to claim 9, <4> In the heating step, heating is performed immediately after the liquid is applied to the powder layer. <1> from <3> 10. A method for producing a three-dimensional object according to claim 9, <5> The powder is characterized in that it is a secondary particle containing a primary particle. <1> from <4> 10. A method for producing a three-dimensional object according to claim 9, <6> The particle size of the primary particles is 10 μm or less. <5> 2. A method for producing a three-dimensional object according to claim 1 . <7> The secondary particles contain a binder resin. <5> or <6> 2. A method for producing a three-dimensional object according to claim 1 . <8> The binder resin contains at least one of polyvinyl butyral, polyvinyl acetate, and acrylic polyol. <7> 2. A method for producing a three-dimensional object according to claim 1 . <9> The liquid contains one or more of dimethyl sulfoxide, diacetone alcohol, and ethyl acetate. <1> from <8> 10. A method for producing a three-dimensional object according to claim 9, <10> The present invention relates to an apparatus for forming a three-dimensional object, the apparatus comprising: a forming unit that forms a powder layer using a powder containing a ceramic material; an application unit that applies liquid to the powder layer; and a heating unit that heats the powder layer to which the liquid has been applied, the apparatus being characterized in that the heating unit controls the temperature of the powder layer to which the liquid has been applied to be between 30°C and 60°C. <11> a data storage unit that stores data including modeling conditions including at least one of the amount or area of ​​the liquid applied by the application unit, or the temperature of the powder layer; a measurement unit that measures the viscosity of a modeled object; a learning unit that extracts features based on the data stored in the data storage unit, and learns a relationship between the viscosity of the modeled object and the modeling conditions based on the features; an estimation unit that estimates the modeling conditions corresponding to the input viscosity of the modeled object based on the learning by the learning unit; and a control unit that controls the application unit or the heating unit based on the modeling conditions estimated by the estimation unit. <10> 2 is a molding apparatus according to the first embodiment. <12> <10> or <11> and a sintering device having a sintering section that sinters a molded object.

[0104] The above <1> from <9> The method for producing a three-dimensional object according to any one of the preceding claims. <10> or <11> 2. The molding apparatus according to claim 1 , <12> According to the molding system described above, the conventional problems can be solved and the object of the present invention can be achieved. [Explanation of symbols]

[0105] 1 forming part 2. Granting Department 3 heating section 4 Vibration applying section 5. Measurement section 6 Control Unit 8 Sintering Section 51 powder 56 powder layer 58 liquid 85 Data Storage Department 86 Learning Department 87 Estimation Department 100 Modeling System 102 Molding equipment 105 Sintering Equipment [Prior art documents] [Patent documents]

[0106] [Patent Document 1] Patent Publication No. 2022-026529

Claims

1. A forming step of forming a powder layer using a powder containing a ceramic material; applying a liquid to the powder layer; and a heating step of heating the powder layer to which the liquid has been applied, a viscosity of a shaped object obtained by repeating the forming step and the applying step one or more times is 1,000 Pa·s or more and 100,000 Pa·s or less; The method for manufacturing a three-dimensional object, wherein in the heating step, a temperature of the powder layer to which the liquid has been applied is controlled to be 30° C. or higher and 60° C. or lower.

2. a measuring step of measuring a viscosity of the object after the heating step, The method for manufacturing a three-dimensional object according to claim 1 , further comprising adjusting an amount or area to which the liquid is applied so that the viscosity becomes a predetermined value.

3. The method for manufacturing a three-dimensional object according to claim 1 , further comprising a vibration step of applying vibration to the object after the heating step.

4. The method for manufacturing a three-dimensional object according to claim 1 , wherein in the heating step, the powder layer is heated immediately after the liquid is applied to the powder layer.

5. The method for producing a three-dimensional object according to claim 1 , wherein the powder is a secondary particle containing a primary particle.

6. The method for producing a three-dimensional object according to claim 5 , wherein the primary particles have a particle size of 10 μm or less.

7. The method for producing a three-dimensional object according to claim 5 , wherein the secondary particles contain a binder resin.

8. The method for manufacturing a three-dimensional object according to claim 7, wherein the binder resin contains at least one of polyvinyl butyral, polyvinyl acetate, and acrylic polyol.

9. The method for manufacturing a three-dimensional object according to claim 1 , wherein the liquid contains at least one of dimethyl sulfoxide, diacetone alcohol, and ethyl acetate.

10. An apparatus for forming a three-dimensional object, comprising: a forming unit that forms a powder layer using a powder containing a ceramic material; An application unit that applies a liquid to the powder layer; a heating unit that heats the powder layer to which the liquid has been applied, The temperature of the powder layer to which the liquid has been applied is controlled to 30° C. or more and 60° C. or less by the heating unit. Modeling equipment.

11. a data storage unit that stores data including a modeling condition including at least one of an amount or area of ​​the liquid applied by the application unit, or a temperature of the powder layer; and A measurement unit that measures the viscosity of the object; a learning unit that extracts feature amounts based on the data stored in the data storage unit, and learns a relationship between the viscosity of the object and the modeling conditions based on the feature amounts; and an estimation unit that estimates the modeling conditions corresponding to the input viscosity of the modeled object based on learning by the learning unit; and a control unit that controls the applying unit or the heating unit based on the modeling conditions estimated by the estimation unit. The molding apparatus of claim 10.

12. 12. A molding system comprising: the molding apparatus according to claim 10 or 11; and a sintering apparatus including a sintering unit that sinters a molded object.

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