Manufacturing method of three-dimensional object

Abstract

To provide a production method of a three-dimensional molded object capable of holding a high temperature of a material in processes, by suppressing thermal conduction by devising a shape of a three-dimensional molded object, for controlling a metal tissue and mechanical characteristics of the three-dimensional molded object.SOLUTION: There is provided a method for producing a three-dimensional molded object 10 in which a molded object layer is laminated using a metal powder lamination molding device, in which, the three-dimensional molded object 10 has a slender rod support part 30 which is connected to the base 20 and is formed into a shape in which thermal resistance becomes a prescribed value, a shell shaped main body part 50, and a taper shape part 40 for connecting, the main body part 50 and the slender rod support part 30 in a structural state. The metal powder lamination molding device comprises: a step for forming a thin layer of a powder material including metal particles; a step for selectively radiating laser light to the thin layer, for forming a molded object layer in which the metal particles included in the powder material are sintered or molten and coupled; and a step for, repeating multiple times the step for forming the thin layer and the step for forming the molded object layer in the order, for laminating the molded object layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a three-dimensional object using powder bed fusion. [Background technology]

[0002] Powder Bed Fusion (PBF) uses a laser or electron beam to locally and instantaneously melt and solidify raw material powder to produce samples of any shape (see, for example, Patent Documents 1 and 2). PBF is characterized by faster cooling and solidification rates than processes such as forging and casting. Due to the thermal history during this process, the metal structure of the resulting sample tends to become finer, which also affects its mechanical properties.

[0003] In particular, because metal structures with fine structures have poor ductility, heat treatment is generally performed on samples fabricated by powder bed fusion to coarsen the crystal grains of the fabricated samples. Furthermore, there have been reported studies on changing the metal structure and mechanical properties of fabricated samples by changing process conditions (e.g., heat source output, scanning speed, substrate temperature [see, for example, Non-Patent Document 1]). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3010312 [Patent Document 2] Japanese Patent Application Laid-Open No. 2018-80393 [Non-patent literature]

[0005] [Non-Patent Document 1] R. Mertens et al. “Application of base plate preheating during selective laser melting” Procedia CIRP 74 (2018) 5-11, Science Direct Summary of the Invention [Problem to be solved by the invention]

[0006] As explained above, in conventional powder bed fusion, raw material powder is melted and solidified locally and instantaneously using a laser or electron beam, but the cooling rate of the three-dimensional object is fast, and the raw material powder solidifies instantaneously. Therefore, since the mechanical properties are improved by heat treatment after the fabrication process, such as coarsening of the metal structure, phase transformation, and precipitation, there was an issue that there was room for improvement in the manufacturing process. The present invention aims to solve the above-mentioned problems and provides a method for manufacturing a three-dimensional object that suppresses heat conduction by devising the shape of the three-dimensional object, thereby maintaining a high material temperature of the metal powder during the manufacturing process and enabling control of the metal structure and mechanical properties of the three-dimensional object. [Means for solving the problem]

[0007] [1] The method for manufacturing a three-dimensional object of the present invention is, for example, a method for manufacturing a three-dimensional object 10 by stacking object layers using a metal powder additive manufacturing apparatus, as shown in FIG. 1, wherein the three-dimensional object 10 is connected to a base 20 and includes a thin rod support portion 30 having a shape that provides a predetermined thermal resistance, a shell-shaped main body portion 50, and a tapered portion 40 that structurally connects the main body portion 50 and the thin rod support portion 30; The metal powder additive manufacturing apparatus includes a step of forming a thin layer of powder material containing metal particles; selectively irradiating the thin layer with a laser beam to form a shaped object layer in which metal particles contained in the powder material are sintered or melt-bonded; The method includes a step of repeating the step of forming the thin layer and the step of forming the object layer in this order a plurality of times to stack the object layers.

[0008] [2] In the method for manufacturing a three-dimensional object of the present invention, the step of stacking the object layers preferably includes a step of forming a thin rod support portion 30, a step of forming a tapered-shaped portion 40 connected to the thin rod support portion 30, and a step of forming a main body portion 50 connected to the tapered-shaped portion 40. [3] In the method for forming a three-dimensional object of the present invention, preferably, the tapered portion 40 has a shape that expands from the thin rod support portion 30 side toward the main body portion 50 side, and the angle of expansion is greater than or equal to 60 degrees and less than or equal to 120 degrees in total.

[0009] [4] In the method for manufacturing a three-dimensional object of the present invention, preferably, the shape of the thin rod support portion 30 that makes the thermal resistance of the thin rod support portion 30 a predetermined value is determined so that, in the process of manufacturing the main body portion 50, the temperature rise of the object layer in the process of forming the object layer by irradiating laser light using the metal powder additive manufacturing device satisfies the heat treatment temperature and heat treatment time of the object layer. [5] In the method for forming a three-dimensional object of the present invention, the heat treatment temperature and heat treatment time of the object layer may be determined so that the crystal grain shape of the powder material of the object layer maintains a predetermined crystal grain size, for example, 60 to 180 μm, which corresponds to the ASTM grain size range of 2-5. [6] In the method for forming a three-dimensional object of the present invention, the main body 50 is preferably a turbine stator blade or a turbine rotor blade.

[0010] [7] The method for forming a three-dimensional object of the present invention preferably further includes a step of removing the tapered portion 40 from the main body portion 50, or a step of removing the thin rod support portion 30 from the tapered portion 40.

[0011] In the method for manufacturing a three-dimensional object according to the present invention, the tapered portion and the thin rod support portion are structurally connected to the main body, thereby suppressing heat conduction to the base and maintaining a high temperature of the manufacturing sample during the manufacturing process of the three-dimensional object, thereby controlling the metal structure and mechanical properties of the manufacturing sample. The shapes of the tapered portion and thin rod support portion are such that the cross-sectional area of ​​the sample (the area of ​​the cross section parallel to the substrate) is reduced, and when the main body is fabricated using powder bed fusion, heat conduction to the base via the tapered portion and thin rod support portion is suppressed, making it possible to maintain a high temperature at the main body. The temperature at which the main body is maintained changes depending on how much the cross-sectional area of ​​the tapered portion and thin rod support portion is reduced, and the metal structure and mechanical properties of the main body can also be controlled. [Effects of the Invention]

[0012] In the powder bed fusion method of the present invention, the metal powder material can be maintained at a high temperature during the manufacturing process, and the formation of crystal grains can be controlled by slowing the cooling and solidification rates. Therefore, by maintaining a high temperature during the manufacturing process, the coarsening of the metal structure, phase transformation, precipitation, etc. caused by conventional heat treatment after the manufacturing process can be replaced, eliminating the need for heat treatment after the manufacturing process and simplifying the manufacturing process. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a front view of a shaped object showing an embodiment of the present invention. [Figure 2] FIG. 1 is an overall functional block diagram showing one embodiment of a metal powder 3D printer used in the powder bed fusion method of the present invention. [Figure 3] 1 is a flowchart of a method for forming a three-dimensional object according to an embodiment of the present invention. [Figure 4] 1 is a flowchart of a method for forming a three-dimensional object according to an embodiment of the present invention. [Figure 5A] 1 is a photograph showing the microstructure of a cross section of a shaped object taken with a scanning electron microscope (SEM) according to an embodiment of the present invention, illustrating a base 20. FIG. [Figure 5B]1 is a photograph showing the microstructure of a cut surface of a shaped object taken with a scanning electron microscope (SEM) according to an embodiment of the present invention, illustrating a tapered portion 40. FIG. [Figure 5C] 1 is a photograph showing the microstructure of a cross section of a shaped object taken with a scanning electron microscope (SEM) according to an embodiment of the present invention, illustrating a main body portion 50. FIG. [Figure 6A] 1 is a photograph showing crystal grains in a cross section of a shaped object by electron backscatter diffraction (EBSD), illustrating one embodiment of the present invention, and shows a base 20. FIG. [Figure 6B] 1 is a photograph showing crystal grains in a cross section of a shaped object by electron backscatter diffraction (EBSD), illustrating one embodiment of the present invention, and shows a tapered portion 40. FIG. [Figure 6C] 1 is a photograph showing crystal grains in a cross section of a shaped object obtained by electron backscatter diffraction (EBSD), illustrating one embodiment of the present invention, and shows a main body portion 50. FIG. [Figure 7A] The width and length of the grains obtained from the EBSD images are plotted against the height of the part. [Figure 7B] The width and length of the grains obtained from the EBSD images are plotted against the height of the part. [Figure 8] FIG. 10 is a diagram showing the results of a hardness test in accordance with an embodiment of the present invention, illustrating the distribution in the height direction of a shaped object. [Figure 9] 1 is an explanatory diagram of a temperature distribution measured by an infrared camera on a molded object according to an embodiment of the present invention, showing the temperature distribution for each part of the molded object. [Figure 10] FIG. 10 is an explanatory diagram of the temperature distribution measured on a molded object by an infrared camera, illustrating the distribution in the height direction of the molded object, according to an embodiment of the present invention. [Figure 11] This is an explanatory diagram of the measured temperature distribution of a molded object using thermal analysis using the finite element method, showing the distribution in the height direction of the molded object. [Figure 12] This is an explanatory diagram of the measured temperature distribution of a molded object using thermal analysis using the finite element method, showing each part of the molded object. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention will be described below with reference to the drawings. FIG. 1 is a front view of a molded object according to one embodiment of the present invention. The method for manufacturing a three-dimensional object of the present invention is a method for manufacturing a three-dimensional object 10 by stacking object layers using a metal powder additive manufacturing apparatus. The three-dimensional object 10 includes a base 20, a thin rod support portion 30, a tapered portion 40, and a main body portion 50, with the main body portion 50 being the final manufacturing object. Therefore, in order to obtain the main body portion 50, which is the final manufacturing object, it is preferable to include a step of removing the tapered portion 40 from the main body portion 50, or a step of removing the thin rod support portion 30 from the tapered portion 40.

[0015] The base 20 is provided at the site where one end of the thin rod support part 30 is joined, in order to facilitate handling of the three-dimensionally shaped object 10 in a state where the thin rod support part 30 is connected to the tapered part 40. In this embodiment, the base 20 has a disk shape with an outer diameter Φ2 of 14 mm and a thickness (H0-H1) of 5 mm, but is not limited to this shape.

[0016] The thin rod support member 30 is a rod-shaped member connected at one end to the base 20 and has a shape that provides a predetermined thermal resistance, e.g., an outer diameter Φ1 of 2.5 mm and a length (H1-H2) of 10 mm. The shape of the thin rod support member 30 that provides the predetermined thermal resistance may be determined so that, in the process of forming the main body 50, the temperature of the object layer in the process of forming the object layer by irradiating the object layer with laser light using a metal powder additive manufacturing device satisfies the heat treatment temperature and heat treatment time of the object layer. The heat treatment temperature and heat treatment time of the object layer may be determined so that the crystal grain shape of the powder material of the object layer maintains a predetermined crystal grain size.

[0017] The tapered portion 40 structurally connects the main body portion 50 and the thin rod support portion 30, and has the same cross-sectional shape as the thin rod support portion 30 at height H2, and the same cross-sectional shape as the main body portion 50 at height H3. The length (H2-H3) of the tapered portion 40 is 5 mm. The umbrella shape of the tapered portion 40 expands from the thin rod support portion 30 side to the main body portion 50 side, and the expansion angle is preferably between 60 degrees and 120 degrees in total, and is approximately 98 degrees in this case.

[0018] In this embodiment, the main body 50 has a round bar shape with a circular cross section, an outer diameter Φ2 of 14 mm, and a length (H4-H3) of 30 mm, but is not limited to this shape and may also have a shell shape with a concave curved surface, such as a turbine stator blade or turbine rotor blade.

[0019] A molded object having such a shape is manufactured using, for example, a metal powder additive manufacturing apparatus called SLM280 manufactured by SLM Solutions GmbH, located in Lübeck, Federal Republic of Germany. Metal powder additive manufacturing apparatuses are known, for example, from Patent Document 2 mentioned above.

[0020] [Outline of the laser metal powder additive manufacturing device] 2 is an overall functional block diagram showing an embodiment of a metal powder 3D printer used in the powder bed fusion method of the present invention. Referring to FIG. 2, the additive manufacturing apparatus 100 is, for example, a laser additive manufacturing apparatus. The additive manufacturing apparatus 100 includes a laser device 110, a galvanometer mirror 120, a control device 130, and a chamber 200.

[0021] The laser device 110 emits laser light. The laser device 110 is, for example, a fiber laser or a CO2 laser. The laser device 110 may be provided with a lens system (not shown). The lens system receives the laser light from the laser device 110 and focuses the laser light to form a laser 112. The galvanometer mirror 120 controls the irradiation of the laser 112. In other words, the galvanometer mirror 120 adjusts the position where the laser 112 is irradiated.

[0022] The chamber 200 includes a layer formation chamber 210, a modeling table 230, a powder supply chamber 220, and a recoater 250. To prevent oxidation of the metal powder particles 140 during irradiation with the laser 112, the chamber 200 is filled with an inert gas (argon, nitrogen, etc.) or maintained in a vacuum state.

[0023] The layer formation chamber 210 is a housing-like structure with an opening at the top. The modeling table 230 is housed in the layer formation chamber 210 and supported so as to be movable up and down. The modeling table 230 is raised and lowered by a motor (not shown).

[0024] The powder supply chamber 220 is located next to the layer formation chamber 210. The powder supply chamber 220 is shaped like a housing and includes a piston 240 that can move up and down. Metal powder particles 140 are stacked on the piston 240. The metal powder particles 140 serve as the raw material for the molded object. As the piston 240 rises, a layer of the metal powder particles 140 is discharged from the top opening of the layer formation chamber 210. The metal powder particles 140 are, for example, highly heat-resistant metal powders of nickel-based superalloys, cobalt-based superalloys, or iron-based superalloys, and are commercially available under the trade name Hastelloy. Note that instead of the metal powder particles 140, ceramics such as Al2O3 may be used together with the metal powder particles 140, or inorganic powder particles such as ceramic particles may be used alone.

[0025] The recoater 250 is disposed near the upper opening of the powder supply chamber 220. The recoater 250 is moved in a specific direction (horizontal direction) by a motor (not shown), and reciprocates between the powder supply chamber 220 and the layer formation chamber 210. In Figure 2, the recoater 250 reciprocates in the X direction. The recoater 250 moves in the X direction, thereby moving the layer of metal powder particles 140 discharged from the powder supply chamber 220 in the horizontal direction and supplying it to the layer formation chamber 210. The metal powder particles 140 deposited on the modeling table 230 in the layer formation chamber 210 form a metal powder layer 260 made of the metal powder particles 140 on the modeling table 230. As the recoater 250 moves in the X direction, the metal powder particles 140 move in the horizontal direction, smoothing the surface of the metal powder layer 260.

[0026] The control device 130 includes a central processing unit (CPU), a memory, and a hard disk drive (hereinafter referred to as HDD), which are not shown. The HDD stores well-known CAD (Computer Aided Design) applications and CAM (Computer Aided Manufacturing) applications. The control device 130 uses the CAD application to create three-dimensional shape data of the object to be manufactured.

[0027] The control device 130 further uses a CAM application to create processing condition data based on the three-dimensional data. In the additive manufacturing method, a model is formed by stacking multiple model portions formed by the laser 112. The processing condition data includes the processing conditions when each model portion is formed. In other words, processing condition data is created for each model portion. The control device 130 controls the laser device 110, the lens system, and the galvanometer mirror 120 based on the processing condition data to adjust the output, scanning speed, scanning interval, and irradiation position of the laser 112.

[0028] [Manufacturing process details] 3 and 4 are flowcharts of a method for manufacturing a three-dimensional object according to one embodiment of the present invention. In the metal powder additive manufacturing apparatus, the above-mentioned object is manufactured in the following steps according to the flowchart shown in FIGS. As a preliminary preparation step for the metal powder additive manufacturing apparatus, a vacuum pump is used to evacuate the chamber 200. After the chamber 200 is evacuated, an inert gas (argon, nitrogen, etc.) is supplied into the chamber 200. The manufacturing table 230 of the layer formation chamber 210 may be preheated.

[0029] Next, a metal powder layer 260, which is a thin layer of powder material containing metal particles, is formed (S100). Next, a laser beam is selectively irradiated onto the thin layer to form a model layer in which the metal particles contained in the powder material are sintered or melt-bonded (S110). The steps of forming the thin layer and forming the model layer are repeated in this order multiple times to stack the model layers (S120).

[0030] In the step of stacking the object layers (S120), first, the base 20 is formed (S122). Next, the thin rod support portion 30 is formed (S124). Next, the tapered portion 40 connected to the thin rod support portion 30 is formed (S126). Next, the main body portion 50 connected to the tapered portion 40 is formed (S128). In the step of forming the main body portion, the temperature rise of the object layer in the step of forming the object layer by irradiating it with laser light using a metal powder additive manufacturing device is determined so as to satisfy the heat treatment temperature and heat treatment time of the object layer, and as a result, the crystal grain shape of the powder material of the object layer located in the main body portion 50 maintains a predetermined crystal grain size (S129). Then, the tapered portion 40 is removed from the main body portion 50, or the thin rod support portion 30 is removed from the tapered portion 40 (S130), to obtain the desired shape of the main body portion 50 (S132). In this way, the desired shape of the three-dimensional object is obtained (S140). [Example]

[0031] In this example, Hastelloy X alloy was used as the raw material for the metal powder. The manufacturer, Hayes International, provides documentation for the hardness and grain size of this metal powder, based on the material solution-treated at 1177°C. The typical ASTM grain size of 2-5 corresponds to an average grain size of 60-180 μm. [Table 1]

[0032] FIG. 5 is a photograph showing the microstructure of a cross section of a molded object taken with a scanning electron microscope (SEM), illustrating one embodiment of the present invention, where (A) shows the base 20, (B) shows the tapered portion 40, and (C) shows the main body portion 50. FIG. 6 is a photograph showing the crystal grains of the cross section of a molded object by electron backscatter diffraction (EBSD), illustrating one embodiment of the present invention, where (A) shows the base 20, (B) shows the tapered portion 40, and (C) shows the main body portion 50.

[0033] Figure 7 shows the width and length of the crystal grains obtained from the EBSD image plotted against the height of the built object. The crystal grains were measured by counting the number of intersections between a line and the grain boundary, and then dividing the line length by the number of intersections, as per "JIS G 0551:2020 Steel - Microscopic Test Method for Grain Size." Because the crystal grains had grown elongated in the build direction (height direction), lines were drawn horizontally (perpendicular to the build direction) and vertically (parallel to the build direction) on the image, and these were used to represent the width and length of the crystal grains, respectively. As shown in Figure 7, the crystal grains in the base 20 are 25 µm or less in width and 50 µm or less in length. In the tapered portion, the width of the crystal grains increases from 27.5 µm to 33.2 µm and the length from 55.7 µm to 84.5 µm as the build height increases from 15 mm to 20 mm. On the other hand, the crystal grains in the molded object located 50 µm below the main body portion are 30 µm to 50 µm in width and 60 µm to 155 µm in length. In other words, the structure is coarser in the main body portion 50 and the tapered portion 40 compared to the base 20.

[0034] FIG. 8 shows the results of a hardness test according to an embodiment of the present invention, illustrating the distribution of hardness in the height direction of the shaped object. At heights of 20-50 mm, which corresponds to the height range (H4-H3) of the main body 50, the Vickers hardness Hv is 190-220. In contrast, at heights of 15-20 mm, which corresponds to the height range (H2-H3) of the tapered-shaped portion 40, the Vickers hardness Hv is 210-250. At heights of 5-15 mm, which corresponds to the height range (H1-H2) of the thin rod support portion 30, the Vickers hardness Hv is 265-275. At heights of 0-5 mm, which corresponds to the height range (H0-H1) of the base 20, the Vickers hardness Hv is 265-275. In other words, the material of the main body 50 is softer than that of the tapered-shaped portion 40 and the thin rod support portion 30.

[0035] FIG. 9 is an explanatory diagram of the temperature distribution measured by an infrared camera on a molded object according to one embodiment of the present invention, showing each part of the molded object. The infrared camera used was a FAST M350 manufactured by Telops. The temperature distribution was measured at a frame rate of 4 Hz and an exposure time of 100 μs. The figure shows the temperature distribution measured immediately after laser irradiation of each layer. In this example, the metal powder additive manufacturing device produced 1,668 layers, a height of 50 mm, and a total elapsed time from the first layer to the final layer of 5 hours, 32 minutes, and 57 seconds. The build height and number of layers were 4.98 mm and the 167th layer for H1 in Figure 1, 15.00 mm and the 500th layer for H2, and 19.98 mm and the 667th layer for H3. The build time was 33 minutes and 13 seconds for H1, 1 hour, 39 minutes, and 50 seconds for H2, and 2 hours, 13 minutes, and 1 second for H3.

[0036] FIG. 10 is an explanatory diagram of the temperature distribution measured on the outermost surface of a molded object using an infrared camera, illustrating one embodiment of the present invention, showing the distribution in the height direction of the molded object. The vertical axis represents the temperature distribution, and the horizontal axis represents the molding time. The frame rate is 4 Hz, and the temperature measurement values ​​represent a moving average every 20 frames (5 seconds). The measured temperature distribution of the base 20 was in the range of 50-300°C over a time range of 0-1993 seconds. The measured temperature distribution of the thin rod support portion 30 was in the range of 50-200°C over a time range of 1994-5990 seconds. The measured temperature distribution of the tapered-shaped portion 40 was in the range of 100-1100°C over a time range of 5991-7981 seconds, with the temperature being lower on the side closer to the thin rod support portion 30 and increasing as the temperature approached the main body portion 50. In contrast, the measured temperature distribution of the main body portion 50 was higher at 1000-1100°C over a time range of 7982-19977 seconds near the tapered-shaped portion 40, but slightly lower at 800-900°C near the top end of the main body portion 50.

[0037] Figure 11 is an explanatory diagram of the measured temperature distribution of the molded object using thermal analysis using the finite element method, showing the distribution in the height direction of the molded object. In the area corresponding to the base 20, the temperature distribution was 50-400°C. In the area corresponding to the thin rod support portion 30, the temperature distribution was 100-400°C. In the area corresponding to the tapered portion 40, the temperature distribution was 150-1300°C. In these areas, the energy from the laser light irradiation by the metal powder additive manufacturing device is also diffused toward the base 20, and the temperature of the processed area does not rise. The surface temperature distribution was 1150-1250°C in the areas of the main body 50 close to the tapered portion 40. In these areas, the energy generated by the laser light irradiation by the metal powder additive manufacturing device was prevented from diffusing toward the base 20 due to the high thermal resistance of the thin rod support portion 30, and the processing temperature of the main body 50, which is the processing area, was maintained at 1150-1250°C.

[0038] Figure 12 is an explanatory diagram of the measured temperature distribution of the molded object using thermal analysis using the finite element method, and shows each part of the molded object. The finite element method was performed using ABAQUS 2019 software from Dassault Systems. Thermal analysis of each layer using a metal powder additive manufacturing device was performed using the finite element method. Surface temperature calculations using the finite element method showed that the temperature distribution in the layer corresponding to the base 20 was 50-250°C. In the layer corresponding to the thin rod support portion 30, the temperature distribution ranged from 50-850°C, with the temperature lower on the side closer to the thin rod support portion 30 and increasing as the temperature approached the main body portion 50. In the area near the tapered portion 40 of the main body portion 50, the temperature distribution was 800-950°C.

[0039] In the above embodiment, the energy generated by the laser light irradiation by the metal powder additive manufacturing device is retained at the processing site of the main body 50, and thermal diffusion to the base side is prevented by the high thermal resistance of the thin rod support portion 30. However, the present invention is not limited to this embodiment, and various embodiments are possible within the scope that is obvious to those skilled in the art. [Industrial Applicability]

[0040] According to the powder bed fusion method of the present invention, the energy generated by the laser light irradiation by the metal powder additive manufacturing device is retained at the processing site of the main body 50, and thermal diffusion to the base side is prevented by the high thermal resistance of the thin rod support portion 30. Therefore, the crystal particle shape of the powder material of the object layer that constitutes the main body 50 maintains a large crystal grain size, and post-processing such as coarsening of the metal structure by heat treatment after the manufacturing process, or improvement of mechanical properties by phase transformation or precipitation can be omitted. [Explanation of symbols]

[0041] 10: Three-dimensional sculpture 20: Foundation 30: Thin rod support part 40: Tapered section 50: Main body 100: Additive manufacturing equipment 110: Laser device 112: Laser 120: Galvanometer mirror 130: Control device 140: Metal powder particles 200: Chamber 210: Layer formation chamber 220: Powder supply room 230: Modeling table 250: Recoater 260: Metal powder layer

Claims

1. A method for manufacturing a three-dimensional object by stacking object layers using a metal powder additive manufacturing apparatus, the three-dimensional object comprising: a thin rod support portion connected to the base and having a shape that provides a predetermined thermal resistance; a shell-shaped main body; a tapered portion that structurally connects the main body portion and the thin rod support portion; Equipped with The metal powder additive manufacturing apparatus includes: forming a thin layer of powder material comprising metal particles; selectively irradiating the thin layer with a laser beam to form a shaped object layer in which metal particles contained in the powder material are sintered or melt-bonded; a step of repeating the step of forming the thin layer and the step of forming the object layer in this order a plurality of times to stack the object layers; A method for forming a three-dimensional object, comprising: The step of stacking the object layers includes: forming the thin rod support portion; forming the tapered portion connected to the thin rod support portion; forming a main body portion connected to the tapered portion; A method for forming a three-dimensional object comprising the steps of:

2. the tapered portion has a shape expanding from the thin rod support portion side to the main body portion side, and the expanding angle is equal to or greater than 60 degrees and equal to or less than 120 degrees in total angle; The method for forming a three-dimensional object according to claim 1 .

3. The shape of the thin rod support portion that provides a predetermined thermal resistance is In the step of forming the main body portion, a temperature rise of the object layer in the step of forming the object layer by irradiating the object layer with laser light using the metal powder rapid prototyping device is determined so as to satisfy a heat treatment temperature and a heat treatment time of the object layer. The method for forming a three-dimensional object according to claim 1 or 2.

4. the heat treatment temperature and heat treatment time of the object layer are determined so that the crystal grain shape of the powder material of the object layer maintains a predetermined crystal grain size; The method for forming a three-dimensional object according to claim 3 .

5. The method for forming a three-dimensional object according to claim 1 , wherein the main body portion is a turbine stationary blade or a turbine rotor blade.

6. The method further includes a step of removing the tapered portion from the main body portion, or a step of removing the thin rod support portion from the tapered portion. The method for forming a three-dimensional object according to claim 1 .

Images