Layered structure manufacturing device and layered structure manufacturing method

Abstract

The purpose of the present invention is to provide a layered structure manufacturing device with which it is possible to perform simple modelling of a layered structure. Selected is a layered structure manufacturing device comprising a casing (2) in which a shield gas atmosphere is formed in a space inside thereof, an analysis unit (3) that analyzes the component of the shield gas atmosphere, a control unit (4) having a function of controlling the shield gas atmosphere so as to be constituted from a required component, a modelling unit (7) that forms a modelling solidification layer (25a) and models a connected body (25) in which the modelling solidification layers (25a) are layered, a drying unit (8) for heating and drying the connected body (25), a powder removal unit (9) for removing unneeded raw material powder from the dried connected body (25), and a powder recovery unit (10) for recovering the unneeded raw material powder. The modelling unit (7), the drying unit (8), the powder removal unit (9), and the powder recovery unit (10) are located in the space inside the casing (2).

Description

Apparatus and method for manufacturing laminated structure

[0001] The present invention relates to an apparatus for manufacturing a laminated structure and a method for manufacturing a laminated structure.

[0002] As in additive manufacturing, layered structures can be manufactured using energy beams. For example, based on computer-aided design (CAD) data, metal layers obtained by laser irradiation are sequentially stacked to produce three-dimensional layered structures of any shape.

[0003] Additive manufacturing technology is attracting attention as a promising technology, being applied to fields such as industrial equipment, including aircraft-related components, and medical equipment. Recently, a method for manufacturing laminated structures using the binder jet method has been proposed, in which a laminated structure is obtained by stacking multiple solidified layers formed by applying a binder to a powder bed of raw powder. However, conventional methods for manufacturing laminated structures using the binder jet method have had problems, such as the powder present in the manufacturing stage other than the laminated structure potentially becoming the source of dust explosions or reacting with air components and moisture.

[0004] Patent Document 1 discloses a technique for suppressing dust explosions by forming a resin coating film on the surface of fine particles that become raw material powder. Patent Document 2 discloses a technique for changing the conditions for forming a powder layer depending on the moisture content of the raw material powder, since the liquid bridging force acting between particles varies depending on the moisture content. Patent Document 3 discloses a technique for ALD coating of active metals to enable safe handling of the active metals in air or in high-humidity environments.

[0005] Japanese Patent Application Laid-Open No. 2021-011107 Japanese Patent Application Laid-Open No. 2020-082432 Special Publication No. 2021-504568

[0006] However, as in Patent Documents 1 to 3, conventional binder jet methods for manufacturing layered structures require surface treatment of the raw material powder and changes to the conditions for forming the powder bed, making it difficult to achieve simple manufacturing. Furthermore, there are issues with the binder scattering and the solvent contained in the binder vaporizing and being released to the outside, which can lead to health hazards if workers inhale the binder or vaporized solvent.

[0007] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a laminated structure manufacturing apparatus and a laminated structure manufacturing method that enable simple formation of laminated structures and prevent health hazards.

[0008] In order to solve the above problems, the present invention has the following configuration: [1] A laminated structure manufacturing device that obtains a laminated structure by stacking a plurality of shaped solidified layers formed by applying a binder to a powder bed of raw material powder, the device comprising: a housing that forms a shielding gas atmosphere in an internal space, an analysis unit that analyzes the components of the shielding gas atmosphere, a control unit that has the function of controlling the shielding gas atmosphere to have a required component, a manufacturing unit that forms shaped solidified layers and manufactures a bonded body by stacking the shaped solidified layers, a drying unit that heats and dries the bonded body, a powder removal unit that removes unnecessary raw material powder from the dried bonded body, and a powder recovery unit that recovers the unnecessary raw material powder, wherein the manufacturing unit, the drying unit, the powder removal unit, and the powder recovery unit are located in the internal space of the housing. [2] The laminated structure manufacturing device according to [1], wherein the housing has a plane that divides the space in the vertical direction, and the modeling unit, the drying unit, and the powder removal unit are located in the space above the plane. [3] The laminated structure manufacturing device according to [2], wherein the modeling unit, the drying unit, and the powder removal unit are arranged in this order in one direction on the plane. [4] The laminated structure manufacturing device according to [3], further comprising a first guide rail arranged along the one direction, and wherein a modeling tank having a modeling stage moves on the first guide rail. [5] The laminated structure manufacturing device according to [4], wherein the powder removal unit has an elevating mechanism that moves the modeling stage up and down in the vertical direction. [6] The laminated structure manufacturing device according to [4], further comprising a second guide rail arranged along another direction intersecting with the one direction on the plane, wherein the first guide rail and the second guide rail intersect between the modeling unit and the drying unit, and the modeling tank moves on the first guide rail and the second guide rail. [7] The laminated structure manufacturing device according to any of [1] to [6], wherein the analysis unit has either or both of a moisture concentration meter and a hydrogen concentration meter. [8] The laminated structure manufacturing device according to any of [1] to [6], further comprising a nitrogen PSA device using air as a raw material as a shielding gas supply source that supplies shielding gas to the housing.[9] A method for manufacturing a laminated structure, in which a laminated structure is obtained by stacking multiple shaped solidified layers formed by applying a binder to a powder bed of raw material powder, the method comprising: a manufacturing process for forming shaped solidified layers in a shielding gas atmosphere of required components and manufacturing a bonded body in which the shaped solidified layers are stacked; a drying process for heating and drying the bonded body in a shielding gas atmosphere of required components; and a removal process for removing unnecessary raw material powder from the bonded body dried in a shielding gas atmosphere of required components.

[10] A method for manufacturing a laminated structure according to [9], in which the manufacturing process, the drying process, and the removal process involve controlling either or both of the moisture concentration and the hydrogen concentration of the shielding gas atmosphere.

[11] A method for manufacturing a laminated structure according to [9], in which the manufacturing process, the drying process, and the removal process involve using a shielding gas atmosphere containing oxygen.

[0009] The method for manufacturing a laminated structure of the present invention makes it easy to form a laminated structure and can prevent health hazards.

[0010] Fig. 1 is a block diagram showing an example of the configuration of a laminated structure manufacturing apparatus applicable to this embodiment; Fig. 2 is a side view of a housing constituting the laminated structure manufacturing apparatus applicable to this embodiment; Fig. 3 is a top view of a housing constituting the laminated structure manufacturing apparatus applicable to this embodiment; Fig. 4 is a cross-sectional schematic view of a molding unit constituting the laminated structure manufacturing apparatus of this embodiment when a powder bed is formed; Fig. 5 is a cross-sectional schematic view of a molding unit constituting the laminated structure manufacturing apparatus of this embodiment when a binder is applied.

[0011] Hereinafter, a manufacturing apparatus and a manufacturing method for a laminated structure according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the drawings used in the following description may show characteristic portions enlarged for convenience in order to make the characteristics easier to understand, and the dimensional proportions of the respective components may not necessarily be the same as those in reality.

[0012] The meanings and definitions of terms used in this specification are as follows: A numerical range expressed as "to" means that the numerical values ​​before and after "to" are the lower and upper limits of the numerical range.

[0013] <Laminated structure manufacturing apparatus> First, the configuration of a laminated structure manufacturing apparatus according to one embodiment of the present invention will be described. Fig. 1 is a block diagram showing the configuration of the laminated structure manufacturing apparatus of this embodiment. Fig. 2 is a side (front) view of a housing constituting the laminated structure manufacturing apparatus of this embodiment. Fig. 3 is a top view of a housing constituting the laminated structure manufacturing apparatus of this embodiment. Figs. 4 and 5 are cross-sectional schematic views of a molding unit constituting the laminated structure manufacturing apparatus of this embodiment.

[0014] As shown in Fig. 1, a laminated structure manufacturing apparatus (hereinafter also simply referred to as "manufacturing apparatus") 1 of this embodiment is roughly configured to include a housing 2, an analysis unit 3, a control unit 4, a shielding gas supply unit (shielding gas supply source) 5, and an exhaust gas treatment unit 6. Note that solid arrows shown in Fig. 1 indicate the direction of gas (vapor) flow, and dotted arrows indicate the direction of electrical signal transmission.

[0015] The manufacturing device 1 is a so-called binder jet type manufacturing device that obtains a layered structure by stacking multiple shaped solidified layers formed by applying a binder to a powder bed of raw material powder in a shielding gas atmosphere inside the housing 2.

[0016] 2 and 3, the housing 2 has an airtight space inside, in which are arranged the modeling unit 7, drying unit 8, powder removal unit 9, and powder recovery unit 10. With this structure, a series of operations can be performed within the airtight space of the housing 2, which eliminates the need for surface treatment of the raw material powder or changing the conditions for forming the powder bed, allowing for simple modeling, and also prevents workers from inhaling scattered binder or vaporized solvent, thereby preventing health hazards.

[0017] A work stage 11 is located inside the housing 2. The work stage 11 divides the space inside the housing 2 into an upper space and a lower space.

[0018] The upper surface (plane) 11a of the working stage 11 is a flat surface. As shown in Fig. 3, a first guide rail 12 is disposed on the upper surface 11a of the working stage 11 along the X-axis direction (one direction), and a second guide rail 13 is disposed along the Y-axis direction (the other direction).

[0019] 2 and 3 , in the manufacturing apparatus 1 of this embodiment, a modeling tank 15 having a modeling stage 14 can be transported along the first guide rails 12 and the second guide rails 13 manually or automatically by a control signal from the control unit 4. In other words, the first guide rails 12 and the second guide rails 13 are transport rails for the modeling tank 15 and are part of the transport mechanism for the modeling tank 15.

[0020] Of the above-mentioned modeling unit 7, drying unit 8, powder removal unit 9, and powder recovery unit 10, the modeling unit 7, drying unit 8, and powder removal unit 9 are arranged in this order on the first guide rail 12. That is, the modeling unit 7, drying unit 8, and powder removal unit 9 are arranged along the X-axis direction on the upper surface 11a of the work stage 11 (the upper space inside the housing 2).

[0021] Therefore, by moving the modeling tank 15 along the first guide rail, the modeling tank 15 can be transported to any area of ​​the modeling section 7, drying section 8, and powder removal section 9 depending on the modeling process.

[0022] The first guide rail 12 and the second guide rail 13 intersect between the modeling unit 7 and the drying unit 8. This allows the transport direction of the modeling tank 15 to be changed at the position where the first guide rail and the second guide rail intersect. Therefore, the modeling tank 15 before processing can be kept waiting on the second guide rail 13 and moved from the second guide rail 13 to the first guide rail 12 at any timing, and the processed modeling tank 15 can be moved (waiting or retracted) from the first guide rail 12 to the second guide rail 13. This makes it possible to simultaneously process multiple processes in parallel and to model multiple layered structures under the same conditions, thereby enabling simpler modeling without changing the powder bed formation conditions.

[0023] 3, the housing 2 may be configured to include an upper housing opening door 16 that constitutes a part of the upper side of the housing 2 and is a cover that covers the upper part of the working stage 11. By opening the upper housing opening door 16 upward as needed, the modeling tank 15 can be directly attached and detached from above the working stage 11.

[0024] That is, the second guide rail 13 constitutes a replacement unit 17 of the modeling tank 15. The replacement unit 17 is located on the first guide rail 12 between the modeling unit 7 and the drying unit 8, as shown in FIGS.

[0025] 4 and 5, the modeling unit 7 has a powder bed forming unit 18 and a binder applying unit 19. The powder bed forming unit 18 and the binder applying unit 19 are electrically connected to the control unit 4, and move back and forth in the X-axis direction and the Y-axis direction in response to control signals from the control unit 4.

[0026] The powder bed forming unit 18 has a powder storage unit 20 and a recoater 21. The powder bed forming unit 18 forms a powder bed 22 of raw material powder on the molding stage 14 of the molding tank 15 located in the molding unit 7.

[0027] The powder storage unit 20 stores raw material powder to be supplied to the manufacturing tank 15 to form a powder bed 22 on the manufacturing stage 14. A nozzle for discharging the raw material powder is provided below the powder storage unit 20, and as the powder storage unit 20 moves, the raw material powder is deposited above the upper surface of the manufacturing stage 14, as shown in Figure 4.

[0028] The raw material powder is not particularly limited and can be appropriately selected depending on the application of the laminated structure. Examples of raw material powders include powders of various metals such as magnesium, calcium, chromium, platinum, gold, silver, copper, iron, manganese, molybdenum, cobalt, nickel, hafnium, niobium, titanium, and aluminum, as well as alloys thereof, and ceramic powders. Examples of ceramic powders include powders of silicides, oxides, nitrides, carbides, and borides of the above metals. The raw material powder may be any one of these, a mixed powder of two or more of these, or a mixed powder of a raw material powder and a ceramic powder. In this embodiment, it is preferable to use a precious metal such as gold or platinum, a titanium alloy, or an aluminum alloy as the raw material powder.

[0029] The particle size of the raw material powder is not particularly limited, and can be, for example, about 1 to 200 μm.

[0030] 4, the recoater 21 flattens the surface of the raw material powder (i.e., the surface of the powder bed 22) deposited above the upper surface of the modeling stage 14. As a result, a powder bed 22 of the raw material powder is formed on the modeling stage 14 of the modeling tank 15 located in the modeling unit 7.

[0031] The powder bed 22 is deposited above the upper surface of the manufacturing stage 14 in the manufacturing tank 15 where the raw material powder is placed. The manufacturing stage 14 has the function of moving up and down in the vertical direction (Z-axis direction) inside the manufacturing tank 15. Therefore, the powder bed 22 of the raw material powder is movable up and down, i.e., in the Z-axis direction, within the housing 2.

[0032] To form the powder bed 22, first, the manufacturing stage 14 of the manufacturing tank 15 located in the manufacturing unit 7 is lowered in the Z-axis direction by an arbitrary height Δh. Next, a raw material powder layer is deposited on the upper surface of the manufacturing stage 14 in the manufacturing tank 15, and then the surface of the deposited raw material powder layer is smoothed by the recoater 21. In this way, the powder bed 22 on which the raw material powder layer is deposited to the arbitrary deposition thickness Δh is formed.

[0033] The modeling stage 14 in the modeling tank 15 located in the modeling unit 7 is electrically connected to the control unit 4. Therefore, the lowering distance (movement amount) of the modeling stage 14 is controlled in accordance with a control signal (instruction) from the control unit 4 so that the deposition thickness of the powder bed 22 becomes Δh.

[0034] The binder application unit 19 has a binder application nozzle 23 and a heat source unit 24 for solidifying the binder. The binder application unit 19 selectively applies a binder to a powder bed 22 of raw material powder formed on the modeling stage 14 to bond the raw material powder particles together.

[0035] The binder application nozzle 23 is not particularly limited as long as it has a mechanism for selectively applying the binder supplied from a binder reservoir (not shown) to any position on the powder bed 22. The heat source unit 24 is not particularly limited as long as it is a heat source that can solidify the binder to form the shaped solidified layer 25a.

[0036] The binder is a binding material that binds the raw material powder together. The binder is not particularly limited as long as it can be applied from the binder application nozzle 23, and can be appropriately selected depending on the type of raw material powder and the laminate structure. As the binder, for example, a liquid resin or a solution in which a resin component is dissolved in a solvent (specifically, a mixed solution containing 10 to 25% ethylene glycol, a mixed solution containing 2.5 to 10% ethylene glycol monobutyl ether, etc.) can be used.

[0037] 5, the shaped solidified layer 25a is formed by solidifying a binder applied to a raw material powder layer deposited on the upper surface of the combined body 25 located on the powder bed 22 in the forming tank 15 (i.e., the upper surface of the forming stage 14). In other words, the forming unit 7 forms the shaped solidified layer 25a and forms the combined body 25 in which multiple shaped solidified layers 25a are stacked.

[0038] 2 and 3 , the drying unit 8 is located on the first guide rail 12 and dries the combined body 25 formed in the shaping unit 7. Specifically, the drying unit 8 has a heat source 26 that dries the combined body 25.

[0039] The heat source 26 is attached to a heating chamber 27 that surrounds the periphery of the modeling tank 15 located in the drying unit 8. As shown in Fig. 2, the heating chamber 27 is movable up and down in the vertical direction (Z-axis direction). With the heating chamber 27 lifted upward in the Z-axis direction, the modeling tank 15 is transported from the modeling unit 7 to the drying unit 8 using the first guide rails 12, and then the heating chamber 27 is lowered downward in the Z-axis direction to store the modeling tank 15 inside the heating chamber 27. In this state, the combined body 25 is heated and dried by the heat source 26.

[0040] According to the manufacturing apparatus 1 of this embodiment, the shaping unit 7 and the drying unit 8 are located inside the housing 2, so that the combined body 25 can be dried in a shielding gas atmosphere.

[0041] 2 and 3, the powder removal unit 9 is located on the first guide rail 12, and removes unnecessary raw material powder from the combined body 25 dried in the drying unit 8. As shown in FIG. 2, the powder removal unit 9 has an elevating mechanism 28 that moves the modeling stage 14 up and down in the vertical direction.

[0042] The lifting mechanism 28 has a pedal 28a, which can be operated to move the modeling stage 14 of the modeling tank 15 located in the powder removal unit 9 up and down in the vertical direction (Z-axis direction), thereby removing unnecessary raw material powder around the combined body 25. In the powder removal unit 9, unnecessary raw material powder may be removed from the combined body 25 using an air gun, a suction nozzle, a brush, or the like. The air gun can be positioned above or on the side of the powder removal unit 9 to supply air. The air used is preferably the same as the shielding gas supplied into the housing 2. When removing unnecessary raw material powder using an air gun, it is preferable to have a partition wall separating the drying unit 8 and the powder removal unit 9. The partition wall prevents raw material powder from scattering inside the housing 2. If a partition wall is provided, it is preferable that only the portion through which the modeling tank 15 passes be openable and closable.

[0043] 2, powder collection unit 10 is disposed below work stage 11 (the lower space inside housing 2). Also, as shown in FIGS. 2 and 3, powder collection unit 10 has a powder passing member 29, a tilting member 30, and a collection container 31.

[0044] Powder passing member 29 is a plate-like member having a plurality of holes passing through it from the top to the bottom. Powder passing member 29 is disposed on work stage 11 across the area where refilling unit 17, drying unit 8, and powder removing unit 9 are disposed. Powder passing member 29 is not particularly limited, but may be, for example, a punching board with a plurality of through holes or a member with a mesh structure.

[0045] As shown in FIG. 2, the inclined member 30 is a cylindrical member having a funnel function, and its upper opening is connected to the work stage 11 so as to cover the lower part of the powder passing member 29, and its lower opening is connected to the entrance of the collection container 31.

[0046] The collection container 31 is an airtight container capable of storing the raw material powder. The collection container 31 can be separated from the housing 2 in a sealed state and removed.

[0047] Since the powder recovery section 10 is arranged below the replacement section 17, drying section 8, and powder removal section 9, raw material powder that falls from the molding tank 15 in the replacement section 17, drying section 8, and powder removal section 9 can be recovered into the recovery container 31 via the powder passing member 29 and the inclined member 30.

[0048] In addition, except for the replacing section 17, the drying section 8, and the powder removing section 9, raw material powder spilled onto the upper surface 11a of the work stage 11 can be collected in the collection container 31 by dropping it downward from the powder passing member 29 using an air gun, a suction nozzle, a brush, or the like. The cylindrical space inside the tilting member 30 and the space within the collection container 31 are filled with a shielding gas atmosphere.

[0049] 2 and 3, the housing 2 has a first transfer chamber 32 and a second transfer chamber 33 in the upper space inside the housing 2. The first transfer chamber 32 and the second transfer chamber 33 have the function of evacuating the internal atmosphere and replacing it with a shielding gas. This makes it possible to transfer materials between the inside and outside of the housing 2 while maintaining the shielding gas atmosphere inside the housing 2.

[0050] In this embodiment, the first transfer chamber 32 allows the dried combined body 25 to be taken out from the inside to the outside of the housing 2 .

[0051] Furthermore, the second transfer chamber 33 allows the raw material powder container 34 to be brought in from the outside to the inside of the housing 2. This allows the raw material powder to be replenished in the powder storage section 20 of the manufacturing section 7 in a shielding gas atmosphere, thereby preventing oxidation of the raw material powder and moisture absorption by the raw material powder.

[0052] 2, the housing 2 has a supply port 2a for supplying a shielding gas to an upper space inside the housing 2, and an exhaust port 2b for exhausting the atmospheric gas inside the housing 2. The manufacturing apparatus 1 of this embodiment can form a shielding gas atmosphere in the space inside the housing 2 by exhausting the atmospheric gas inside the housing 2 and supplying a shielding gas.

[0053] The shielding gas is not particularly limited and can be appropriately selected depending on the type of raw material powder. As the shielding gas, an inert gas is preferable, and among these, nitrogen gas and argon gas are more preferable. Depending on the type of raw material powder, a shielding gas containing an oxidizing gas such as oxygen that reacts with the raw material may be used. Here, when a shielding gas containing an oxidizing gas other than an inert gas is used, the raw material powder and the oxidizing gas react with each other, and an oxide film can be formed on the surface of the raw material powder.

[0054] The analysis unit 3 analyzes the components of the atmospheric gas (shielding gas atmosphere) in the space within the housing 2. As shown in Figures 1 and 2, the analysis unit 3 is located on the secondary side of the housing 2 in the flow direction of the shielding gas. The analysis unit 3 preferably has either or both of a hydrogen concentration meter and a moisture concentration meter. This makes it possible to detect the hydrogen concentration or moisture concentration in the atmospheric gas discharged from the space within the housing 2 (i.e., the atmospheric gas within the housing 2).

[0055] The upper limit of the hydrogen concentration in the atmospheric gas inside the housing 2 is preferably set to 4% or less. Incidentally, the binder used in the molding unit 7 may contain moisture. This moisture may react with the raw material powder to generate hydrogen. Therefore, setting the upper limit of the hydrogen concentration to 4% can prevent explosions caused by hydrogen.

[0056] The moisture concentration in the atmospheric gas inside the housing 2 is preferably 1,000 ppm or less. By setting the upper limit of the moisture concentration at 1,000 ppm, moisture adsorption to the raw material powder can be suppressed, and a decrease in the fluidity of the raw material powder can be prevented.

[0057] The analysis unit 3 preferably further includes an oxygen concentration meter, a binder component concentration meter, etc. This makes it possible to analyze the oxygen concentration and binder component concentration in the atmospheric gas within the housing 2.

[0058] The upper limit of the oxygen concentration in the atmospheric gas within the housing 2 is preferably 20,000 ppm or less, and more preferably 10,000 ppm or less from the viewpoint of preventing oxidation of the raw material powder. Furthermore, when the raw material powder is a highly active metal such as a titanium alloy or an aluminum alloy, the lower limit of the oxygen concentration in the atmospheric gas within the housing 2 is preferably 1,000 ppm or more. Setting the lower limit of the oxygen concentration to 1,000 ppm promotes surface oxidation of the raw material powder, thereby preventing rapid oxidation, heat generation, and explosion.

[0059] The binder component concentration in the atmospheric gas inside the housing 2 is preferably 10,000 ppm or less, more preferably 5,000 ppm or less, even more preferably 2,000 ppm or less, and particularly preferably 1,000 ppm or less. Setting the upper limit of the binder component concentration to 10,000 ppm can prevent the binder component from igniting and adhering to the layered object and raw material powder.

[0060] The concentration of each component in the atmospheric gas inside the housing 2 can be adjusted by the amount of shielding gas supplied into the housing 2. That is, by increasing the amount of shielding gas supplied into the housing 2, the concentration of each component can be reduced.

[0061] The control unit 4 has a function of controlling the atmospheric gas (shielding gas atmosphere) in the space within the housing 2 so that it has required components. Specifically, the control unit 4 may calculate the amount of shielding gas to be supplied into the housing 2 from the measured values ​​of the concentrations of each component in the atmospheric gas obtained from the analysis unit 3, and send a supply signal (control signal) to the shielding gas supply unit (shielding gas supply source) 5.

[0062] The control unit 4 may be configured to include a central processing unit (CPU), a memory, and a hard disk drive. The hard disk drive may include a CAD application and a CAM (Computer Aided Manufacturing) application. In this case, the control unit 4 can create three-dimensional structural data for a laminated structure of a desired shape.

[0063] The control unit 4 may be configured to create processing condition data based on the three-dimensional structure data. Processing condition data can be created for each solidified model layer. The control unit 4 may control the powder bed formation unit 18 and the binder application unit 19 based on the processing condition data to adjust the amount of binder applied, the nozzle scanning speed, the scanning interval, and the application position.

[0064] The shielding gas supply unit 5 is a shielding gas supply source that supplies shielding gas into the housing 2. The type of shielding gas supply source is not particularly limited and can be selected appropriately depending on the type and amount of shielding gas used. A gas cylinder, a cold evaporator (CE), a PSA device, etc. can be applied. When nitrogen gas is used as the shielding gas, it is preferable to use a nitrogen PSA device that uses air as the raw material as the shielding gas supply unit 5. By using a nitrogen PSA device as the shielding gas supply unit 5, nitrogen gas containing a trace amount of oxygen can be supplied into the housing 2 as the shielding gas.

[0065] The exhaust gas treatment unit 6 treats the atmospheric gas discharged from the housing 2 as exhaust gas. The exhaust gas treatment unit 6 is not particularly limited and can be appropriately selected depending on the type of shielding gas and the atmospheric gas inside the housing 2. For example, a detoxification device such as a water scrubber, a filter, a trapping device, etc. can be used as the exhaust gas treatment unit 6. By having the exhaust gas treatment unit 6, when at least one of the binder, the vaporized solvent released by vaporizing a solvent (e.g., an organic solvent) contained in the binder, and the raw material powder is discharged, it can be treated by the exhaust gas treatment unit 6 and is not released to the outside, thereby preventing health hazards.

[0066] <Method for Manufacturing a Laminated Structure> Next, a method for manufacturing a laminated structure according to one embodiment of the present invention will be described using the above-described manufacturing apparatus 1 as an example. The method for manufacturing a laminated structure according to this embodiment involves stacking multiple solidified layers 25a formed by applying a binder to a powder bed 22 of raw material powder to obtain a laminated structure. The solidified layers 25a are formed in a shielding gas atmosphere containing required components, a bonded body 25 formed by stacking the solidified layers 25a is formed, the bonded body 25 is heated and dried, and unnecessary raw material powder is removed from the dried bonded body 25. Specifically, the method for manufacturing a laminated structure according to this embodiment involves the following steps.

[0067] (Atmospheric Gas Adjustment Process) In the atmospheric gas adjustment process, the atmospheric gas inside the casing 2 is adjusted to become a shielding gas atmosphere with the required components. First, shielding gas is supplied from the shielding gas supply unit 5 into the casing 2 via the supply port 2a. The atmospheric gas inside the casing 2 is discharged from the discharge port 2b. At this time, the analysis unit 3 analyzes the oxygen concentration, hydrogen concentration, moisture concentration, and binder concentration in the atmospheric gas (shielding gas atmosphere) in the space inside the casing 2.

[0068] The supply of shielding gas into the housing 2 and the analysis of the concentration of each component in the atmospheric gas in the housing 2 are continued, and the manufacturing process is started when the concentration of each component in the atmospheric gas in the housing 2 becomes equal to or less than a required value. When the concentration of each component in the atmospheric gas in the housing 2 becomes equal to or less than a required value, the control unit 4 may perform control to reduce the supply amount of shielding gas.

[0069] The adjustment of the atmospheric gas in the housing 2 continues throughout the molding process, drying process, bond removal process, and raw material powder replenishment process, which will be described later. The concentration of each component in the atmospheric gas in the housing 2 is monitored through analysis by the analysis unit 3, and the supply amount of shielding gas is adjusted, so that the oxygen concentration, hydrogen concentration, moisture concentration, and binder concentration can be controlled so as not to exceed their upper limit values.

[0070] 2 and 3 , the unprocessed shaping tank 15 waiting on the second guide rail 13 is moved along the second guide rail 13 to the position of the replacement unit 17, and then moved along the first guide rail 12 to the position of the shaping unit 7.

[0071] Next, as shown in FIG. 4 , the powder bed forming unit 18 is operated to supply and spread raw material powder from the powder storage unit 20 into the tank of the modeling tank 15 by gravity falling, thereby forming a raw material powder layer of a predetermined thickness on the modeling stage 14. The raw material powder layer is smoothed by a recoater 21 that moves in conjunction with the powder storage unit 20 so that the surface is flat and of uniform thickness. In this way, a powder bed 22 is formed on the modeling stage 14. The thickness of the raw material powder layer is, for example, about 40 to 50 μm, but can be appropriately set within a range of approximately 100 μm or less.

[0072] Next, as shown in FIG. 5 , the binder application unit 19 is operated to selectively spray a binder from a binder application nozzle 23 onto the raw material powder layer (powder bed 22) stacked on the building stage 14. The raw material powder in the area where the binder is sprayed is then heated by a binder solidification heat source 24, and the binder solidifies, bonding and hardening the powder. In this way, a solidified layer 25a is formed on the building stage 14. The binder application nozzle 23 can be computer-controlled by the control unit 4 based on three-dimensional data corresponding to the shape of the desired three-dimensional sintered body (layered structure), and can be driven over the raw material powder layer.

[0073] Next, raw material powder is again supplied from the powder reservoir 20 onto the first raw material powder layer, including the shaped solidified layer 25a bonded by selective binder application, and the layer is flattened by the recoater 21, and a second raw material powder layer is then laminated. Next, a binder is selectively sprayed onto the second raw material powder layer from the binder application nozzle 23, and the raw material powder is bonded by the binder to form the shaped solidified layer 25a.

[0074] In this way, raw material powder is stacked on the first raw material powder layer, which includes a shaped solidified layer 25a bonded by selective binder application, to form the next raw material powder layer, and then binder is selectively sprayed onto that raw material powder layer.This process is repeated multiple times to form a bonded body 25, which is a stack of shaped solidified layers 25a, inside the powder bed 22 consisting of multiple raw material powder layers.

[0075] In addition, in order to form a single bonded body 25, the adjacent overlapping shaped solidified layers 25a are bonded to each other at least partially by overlapping the binder supply portions, thereby forming a continuous bonded body 25 in the vertical direction (Z-axis direction).

[0076] (Drying Process) In the drying process, the combined body 25 is heated and dried. First, as shown in FIGS. 2 and 3 , the modeling tank 15, for which the modeling process has been completed, is moved along the first guide rails 12 from the modeling unit 7 to the drying unit 8. At this time, the heating chamber 27 is retracted upward in the Z-axis direction. Next, the modeling tank 15 is transported to the drying unit 8, and then the heating chamber 27 is lowered downward in the Z-axis direction to store the modeling tank 15 inside the heating chamber 27. In this state, the combined body 25 is heated by the heat source 26 to dry it.

[0077] The binder 25 in the modeling tank 15 is dried by volatilizing the binder component during the drying process. It is preferable that the binder 25 is completely dried to the inside, but a part of the binder 25 may remain dry.

[0078] After the modeling tank 15 for which the modeling process has been completed is moved along the first guide rails 12 from the modeling unit 7 to the position of the drying unit 8, a new modeling tank 15 that has been waiting on the second guide rails 13 of the replacement unit 17 is moved to the modeling unit 7. Then, in the modeling unit 7, the modeling process is started using the new modeling tank 15 in parallel with the drying process. As described above, although it takes time to dry the bonded body 25 in the drying process, according to the manufacturing method of the laminated structure of this embodiment, the modeling process of the new modeling tank 15 is started in parallel with the drying process, thereby improving production efficiency.

[0079] (Removal Process) In the removal process of the combined body 25, unnecessary raw material powder is removed from the dried combined body 25. First, the manufacturing tank 15 that has completed the drying process is moved along the first guide rail 12 from the drying unit 8 to the position of the powder removal unit 9. At this time, the heating chamber 27 is retracted upward in the Z-axis direction. Next, after the manufacturing tank 15 is transported to the powder removal unit 9, the pedal 28a of the lifting mechanism 28 is operated to swing the manufacturing stage 14 of the manufacturing tank 15 up and down in the vertical direction (Z-axis direction), thereby removing unnecessary raw material powder around the combined body 25. Note that the method for removing the raw material powder is not particularly limited, and the unnecessary raw material powder may be removed from the combined body 25 using an air gun, a suction nozzle, a brush, or the like.

[0080] (Step of Removing the Combined Body) Next, the combined body 25 from which the unnecessary raw material powder has been removed is removed from the first transfer chamber 32 to the outside of the housing 2. At this time, it is preferable to gradually open the outer door of the first transfer chamber 32 to gradually replace the atmosphere in the first transfer chamber 32 with air. The rate at which air is introduced into the first transfer chamber 32 is preferably set to a flow rate that allows the atmosphere in the first transfer chamber 32 to be replaced in 10 seconds to 10 minutes. In this way, by gradually increasing the oxygen concentration in the first transfer chamber 32 until it becomes the same as the atmosphere outside the housing 2, a rapid reaction between the raw material powder contained in the combined body 25 and oxygen can be prevented.

[0081] (Sintering Step) Next, the dried bonded body 25 removed from the housing 2 is sintered to obtain a sintered body (laminate structure). Specifically, the bonded body 25 is sintered under required sintering conditions using a heating device such as an oven that can heat at a required temperature. In this way, according to the method for manufacturing a laminated structure of this embodiment, the laminated structure can be obtained through a simple process.

[0082] (Step of Replenishing Raw Material Powder) In addition to the steps described above, the method for manufacturing a laminated structure according to this embodiment includes a step of replenishing raw material powder. Specifically, in the molding unit 7 within the housing 2, the powder reservoir 20 constituting the powder bed forming unit 18 is periodically replenished with raw material powder.

[0083] First, the outer door of the second transfer chamber 33 located at the top of the housing 2 is opened, and the raw material powder container 34 containing the raw material powder is placed inside the chamber, and then the door is closed.

[0084] Next, the atmosphere inside the second transfer chamber 33 is evacuated and then replaced with a shielding gas. This creates a shielding gas atmosphere inside the second transfer chamber 33. After the shielding gas atmosphere has been created inside the second transfer chamber 33, the door on the inside (housing 2 side) of the second transfer chamber 33 is opened, and the raw material powder container 34 is removed into the space inside the housing 2. Next, the raw material powder container 34 is opened, and the powder storage section 20 of the powder bed forming section 18 is replenished with raw material powder.

[0085] As described above, according to the manufacturing method of the laminated structure of this embodiment, raw material powder can be replenished in the powder storage section 20 of the forming section 7 in a shielding gas atmosphere, thereby preventing oxidation of the raw material powder and moisture absorption by the raw material powder.

[0086] (Control by control unit 4) In the manufacturing method of the laminated structure of this embodiment, the above-mentioned atmospheric gas adjustment process, the molding process, and some or all of the drying process, as well as the movement of the molding tank 15 within the housing 2, can also be performed automatically by control signals from the control unit 4.

[0087] Furthermore, in the manufacturing method of the laminated structure of this embodiment, as shown in FIG. 1 , the control unit 4 is electrically connected to the analysis unit 3 and the shielding gas supply unit 5, so that the shielding gas atmosphere in the housing 2 may be automatically controlled by the control unit 4.

[0088] Specifically, the analysis unit 3 has an oxygen concentration meter, and the control unit 4 sets the lower limit of the oxygen concentration in the atmospheric gas within the housing 2 to 0% and the upper limit to 1%. When the oxygen concentration reaches the lower limit, the supply amount (flow rate) of the shielding gas can be reduced. On the other hand, when the oxygen concentration exceeds the upper limit, the supply amount (flow rate) of the shielding gas can be increased and the molding process and drying process can be stopped. Furthermore, when the oxygen concentration exceeds the upper limit, the opening and closing of the housing upper opening door 16, the first transfer chamber 32, and the second transfer chamber 33 can be restricted (locked) from a safety standpoint.

[0089] The analysis unit 3 also includes a hydrogen concentration meter. The control unit 4 sets the lower limit of the hydrogen concentration in the ambient gas within the housing 2 to 0% and the upper limit to 4%. When the hydrogen concentration reaches the lower limit, the supply amount (flow rate) of the shielding gas can be reduced. On the other hand, when the hydrogen concentration exceeds the upper limit, the supply amount (flow rate) of the shielding gas can be increased and the molding process and drying process can be stopped. Furthermore, the opening and closing of the housing top opening door 16, the first transfer chamber 32, and the second transfer chamber 33 can be controlled (locked). This prevents oxygen from flowing into the housing 2 from the outside. For example, when a highly active metal powder is used as the raw material powder, hydrogen generated by the reaction between water and the metal powder can be prevented from causing the atmosphere within the housing 2 to deviate from the safe operating range.

[0090] The analysis unit 3 also has a moisture concentration meter, and the control unit 4 sets the lower limit of the moisture concentration in the atmospheric gas within the housing 2 to 0% and the upper limit to 0.1%. When the moisture concentration reaches the lower limit, the supply amount (flow rate) of the shielding gas can be reduced. On the other hand, when the moisture concentration exceeds the upper limit, the supply amount (flow rate) of the shielding gas can be increased and the molding process and drying process can be stopped. Furthermore, when the moisture concentration exceeds the upper limit, the opening and closing of the housing upper opening door 16, the first transfer chamber 32, and the second transfer chamber 33 can be restricted (locked) from a safety standpoint.

[0091] The analysis unit 3 also has a binder component concentration meter, and the control unit 4 sets the lower limit of the binder component concentration in the atmospheric gas within the housing 2 to 0% and the upper limit to 0.1%. When the binder component concentration reaches the lower limit, the supply amount (flow rate) of the shielding gas can be reduced. On the other hand, when the binder component concentration exceeds the upper limit, the supply amount (flow rate) of the shielding gas can be increased and the molding process and drying process can be stopped. Furthermore, when the binder component concentration exceeds the upper limit, the opening and closing of the housing upper opening door 16, the first transfer chamber 32, and the second transfer chamber 33 can be restricted (locked) from a safety standpoint.

[0092] The analysis unit 3 also has an oxygen concentration meter and a hydrogen concentration meter, and the control unit 4 sets a safe operating range for the atmospheric gas within the housing 2 (for example, a safe range generally indicated by a hydrogen-air-nitrogen triangle diagram). When both the oxygen concentration and the hydrogen concentration are within the safe operating range, the supply amount (flow rate) of the shielding gas can be reduced. On the other hand, when at least one of the oxygen concentration and the hydrogen concentration is outside the safe operating range, the supply amount (flow rate) of the shielding gas can be increased and the molding process and the drying process can be stopped. Furthermore, from a safety standpoint, the opening and closing of the housing top opening door 16, the first transfer chamber 32, and the second transfer chamber 33 can be restricted (locked).

[0093] Furthermore, in the method for manufacturing a laminated structure of this embodiment, as shown in FIG. 1, the control unit 4 is electrically connected to the housing 2, the shielding gas supply unit 5, and the exhaust gas treatment unit 6, so that when various abnormal signals are detected, the control unit 4 can automatically stop the operation of each device.

[0094] Specifically, when the control unit 4 detects an abnormality in the shielding gas supply unit 5, it can stop the manufacturing process and the drying process. Furthermore, when the control unit 4 detects overheating in the drying unit 8, it can increase the supply amount (flow rate) of the shielding gas and stop the manufacturing process and the drying process. Furthermore, when the control unit 4 detects an abnormality in each concentration meter of the analysis unit 3, it can stop the manufacturing process and the drying process. Furthermore, when the control unit 4 detects an abnormality in the exhaust gas treatment unit 6, it can stop the manufacturing process and the drying process. As described above, according to the manufacturing method of the laminated structure of this embodiment, the laminated structure can be manufactured safely.

[0095] As described above, according to the laminated structure manufacturing apparatus 1 and manufacturing method of this embodiment, the forming section 7 and drying section 8 are arranged within the housing 2, and the forming process and drying process can be carried out continuously in the required shielding gas atmosphere, so that a combined body 25 that serves as a precursor to the laminated structure can be easily obtained with a simple device configuration.

[0096] Furthermore, the laminated structure obtained by sintering the bonded body 25 obtained by the laminated structure manufacturing apparatus 1 and manufacturing method of the present embodiment has advantageous effects on various product groups in a wide range of industrial fields. For example, it provides advantages such as being able to satisfy various requirements for the properties of the laminated structure.

[0097] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. According to the manufacturing apparatus 1 and manufacturing method described above, the analysis unit 3 has a hydrogen concentration meter and a moisture concentration meter as an example, but is not limited to this. For example, the analysis unit 3 may not have a hydrogen concentration meter.

[0098] Specifically, the analysis unit 3 may be configured to include an oxygen concentration meter and a moisture concentration meter. When a highly active metal powder is used as the raw material powder, hydrogen may be generated by the reaction between water and the metal powder. In this case, it is preferable to predict the moisture content and hydrogen generation amount depending on the type of metal powder and set an upper limit for the moisture concentration in the atmospheric gas within the housing 2. The control unit 4 then sets a safe operation range (e.g., a safe range generally represented by a hydrogen-air-nitrogen triangular diagram) based on the oxygen concentration and moisture concentration (the amount of hydrogen generation predicted from the moisture concentration) in the atmospheric gas within the housing 2. When the oxygen concentration and moisture concentration fall within the safe operation range, the supply amount (flow rate) of the shielding gas can be reduced. On the other hand, when at least one of the oxygen concentration and moisture concentration falls outside the safe operation range, the supply amount (flow rate) of the shielding gas can be increased and the molding process and drying process can be stopped. Furthermore, from a safety perspective, the opening and closing of the housing top opening door 16, the first transfer chamber 32, and the second transfer chamber 33 can be restricted (locked).

[0099] REFERENCE SIGNS LIST 1 Manufacturing apparatus (apparatus for manufacturing laminated structures) 2 Housing 3 Analysis section 4 Control section 5 Shielding gas supply section (shielding gas supply source) 6 Exhaust gas treatment section 7 Building section 8 Drying section 9 Powder removal section 10 Powder recovery section 11 Work stage 11a Top surface (flat surface) 12 First guide rail 13 Second guide rail 14 Building stage 15 Building tank 16 Housing upper opening door 17 Replacement section 18 Powder bed formation section 19 Binder application section 20 Powder storage section 21 Recoater 22 Powder bed 23 Binder application nozzle 24 Heat source section 25 Bonded body 25a Building solidification layer

Claims

1. A manufacturing apparatus for a laminated structure, which obtains a laminated structure by stacking a plurality of shaped solidified layers formed by applying a binder to a powder bed of raw material powder, A housing that forms a shielding gas atmosphere in an inner space; an analysis unit for analyzing components of the shielding gas atmosphere; A control unit having a function of controlling the shielding gas atmosphere to have a required composition; a molding unit that forms a shaped solidified layer and molds a combined body by stacking the shaped solidified layers; a drying section for heating and drying the bonded body; a powder removing section for removing unnecessary raw material powder from the dried combined body; A powder recovery unit that recovers unnecessary raw material powder, The apparatus for manufacturing a laminated structure, wherein the modeling unit, the drying unit, the powder removal unit, and the powder recovery unit are located in the space inside the housing.

2. the housing has a plane that divides and partitions the space in an up-down direction, The laminated structure manufacturing apparatus according to claim 1 , wherein the modeling unit, the drying unit, and the powder removing unit are located in a space above the plane.

3. The laminated structure manufacturing apparatus according to claim 2 , wherein the modeling unit, the drying unit, and the powder removing unit are arranged in this order in one direction on the plane.

4. Further comprising a first guide rail arranged along the one direction, The laminated structure manufacturing apparatus according to claim 3 , wherein a modeling tank having a modeling stage moves on the first guide rail.

5. The laminated structure manufacturing apparatus according to claim 4 , wherein the powder removing unit has a lifting mechanism that moves the modeling stage up and down in the vertical direction.

6. Further, a second guide rail is provided along another direction intersecting the one direction on the plane, The first guide rail and the second guide rail intersect between the modeling unit and the drying unit, The laminated structure manufacturing apparatus according to claim 4 , wherein the molding tank moves on the first guide rail and the second guide rail.

7. The laminated structure manufacturing apparatus according to claim 1 , wherein the analysis section has one or both of a moisture concentration meter and a hydrogen concentration meter.

8. 7. The laminate structure manufacturing apparatus according to claim 1, further comprising a nitrogen PSA device using air as a raw material as a shielding gas supply source for supplying a shielding gas to the case.

9. A work stage is provided inside the housing, 7. The laminated structure manufacturing apparatus according to claim 1, wherein at least one of the work stage and the powder removal section has at least one of an air gun, a suction nozzle, and a brush, and the at least one of the air gun, the suction nozzle, and the brush removes unnecessary raw material powder from the combined body.

10. A method for manufacturing a laminated structure by stacking a plurality of shaped solidified layers formed by applying a binder to a powder bed of raw material powder, the method comprising the steps of: a molding process in which a shaped solidified layer is formed in a shielding gas atmosphere having a required composition, and a combined body is formed by stacking the shaped solidified layers; a drying step of heating and drying the bonded body in a shielding gas atmosphere of a required composition; and a removing step of removing unnecessary raw material powder from the dried bonded body in a shielding gas atmosphere of a required component.

11. The method for manufacturing a laminated structure according to claim 10 , wherein in the shaping step, the drying step, and the removing step, either one or both of a moisture concentration and a hydrogen concentration of the shielding gas atmosphere are controlled.

12. The method for manufacturing a laminate structure according to claim 10 , wherein the shaping step, the drying step, and the removing step are performed in a shielding gas atmosphere containing oxygen.