Layered manufacturing device and layered manufacturing method

Abstract

To obtain an additive manufacturing device that can control increase in a production cost.SOLUTION: An additive manufacturing device 100 comprises a vacuum chamber 1, a work bed 4 provided in the vacuum chamber 1 and having a vertically height-adjustable work table 41 forming a bottom surface of a molding area R for molding an additive manufacturing object M, a powder supply part 6 that reserves powder material 5 that is a raw material for the additive manufacturing object M and supplies the powder material 5 to the molding area R, an electron gun 2 that irradiates the molding area R with an electron beam EB that solidifies the powder material 5 and is housed in an electron gun chamber 3 having, in a floor 3a, an opening 3b that can be opened and closed during irradiation of the electron beam EB, a shield member 7 provided in the vacuum chamber 1 and covering at least a part of the side surface of a passage area S1 that is an area through which the electron beam EB passes, and a gas supply part 8 that supplies gas that is ionized by the irradiation of the electron beam EB in a gas feed space G that is a space through which the side surface of the passage area S1 is covered by the shield member 7.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an additive manufacturing apparatus and an additive manufacturing method for manufacturing a three-dimensional additively manufactured object using a powder material that can be solidified by irradiating it with an electron beam. [Background technology]

[0002] There is a known additive manufacturing device that builds up powder beds made of powder material, such as metal particles that can be melted and solidified by irradiation with an electron beam, in a vacuum chamber, and then selectively solidifies each layer of the powder bed to create a three-dimensional additively manufactured object.

[0003] In an electron beam-based additive manufacturing device, the powder material becomes negatively charged when irradiated with the electron beam, which can cause the individual powder particles to repel each other due to Coulomb force, resulting in the powder material scattering.

[0004] The method and apparatus for producing three-dimensional objects described in Patent Document 1 describes a technology in which, in order to prevent the powder material from scattering, a scattering prevention gas is introduced into the vacuum chamber of the apparatus, and the scattering prevention gas is positively charged near the irradiation point of the electron beam, thereby electrically neutralizing the powder material.

[0005] Furthermore, the 3D additive manufacturing device described in Patent Document 2 describes a technology in which a metal cover is placed above the manufacturing area, and a positive voltage is applied to the metal cover or the metal cover is set at GND potential, thereby trapping secondary electrons, which are generated in large quantities, with the metal cover and preventing the powder material from scattering. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2010-526694 [Patent Document 2] International Publication No. 2016 / 059644 Summary of the Invention [Problem to be solved by the invention]

[0007] However, because the anti-scattering gas introduced into the vacuum chamber easily diffuses, the method and apparatus for producing three-dimensional objects described in Patent Document 1 introduces the anti-scattering gas to the entire vacuum chamber to prevent the powder material from scattering.As the vacuum chamber becomes larger, particularly when producing large layered objects, the amount of anti-scattering gas required also increases, resulting in increased production costs.

[0008] Even if the 3D additive manufacturing device described in Patent Document 2 is configured to introduce anti-scattering gas, it is necessary to introduce the anti-scattering gas throughout the vacuum chamber, making it impossible to reduce the amount of anti-scattering gas supplied and increasing production costs. Furthermore, the 3D additive manufacturing device described in Patent Document 2 requires a device for applying voltage to the metal cover, which increases the cost of the device.

[0009] The present invention has been made to solve the above-mentioned problems, and aims to provide an additive manufacturing apparatus and an additive manufacturing method that can suppress increases in production costs. [Means for solving the problem]

[0010] The layered manufacturing apparatus of the present invention includes: a vacuum chamber; a work base provided within the vacuum chamber and having a work table whose height is adjustable in the vertical direction and which forms the bottom surface of a manufacturing region for manufacturing a layered object; a powder supply unit that stores powder material as a raw material for the layered object and supplies the powder material to the manufacturing region; an electron gun housed in an electron gun chamber having an opening in its floor that can be opened and closed during electron beam irradiation and that irradiates the manufacturing region with an electron beam that solidifies the powder material; a shield member provided within the vacuum chamber and covering at least a portion of a side surface of a passage region that is a region through which the electron beam passes; and a gas supply unit that supplies a gas that is ionized by electron beam irradiation into a gas supply space that is a space in which the side surface of the passage region is covered with the shield member. The opening communicates the vacuum chamber with the electron gun chamber.

[0011] The layered manufacturing method of the present invention includes a step of supplying a powder material as a raw material of the layered object to a manufacturing region for manufacturing the layered object, and The electron gun is housed in an electron gun chamber that can be opened and closed during electron beam irradiation and has an opening in the floor that connects the vacuum chamber and the electron gun chamber. The electron beam that solidifies the powder material is irradiated by the electron gun. and a step of supplying a gas that is ionized by irradiation with an electron beam into a gas supply space, which is a space in which the side of a passing area is covered by a shielding member that covers at least a portion of the side of the passing area, which is an area through which the electron beam passes. [Effects of the Invention]

[0012] According to the layered manufacturing device of the present invention, an increase in production costs can be suppressed.

[0013] According to the additive manufacturing method of the present invention, an increase in production costs can be suppressed. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic diagram showing an additive manufacturing apparatus according to a first embodiment of the present invention. [Figure 2] 3A to 3C are diagrams illustrating examples of shapes of shield members of the layered manufacturing apparatus according to the first embodiment of the present invention. [Figure 3] FIG. 1 is an explanatory diagram of a layered manufacturing method using the layered manufacturing device according to the first embodiment of the present invention. [Figure 4] FIG. 1 is an explanatory diagram of a layered manufacturing method using the layered manufacturing device according to the first embodiment of the present invention. [Figure 5] FIG. 1 is an explanatory diagram of a layered manufacturing method using the layered manufacturing device according to the first embodiment of the present invention. [Figure 6] FIG. 1 is an explanatory diagram of a layered manufacturing method using the layered manufacturing device according to the first embodiment of the present invention. [Figure 7] FIG. 1 is an explanatory diagram of a layered manufacturing method using the layered manufacturing device according to the first embodiment of the present invention. [Figure 8] FIG. 1 is an explanatory diagram of a layered manufacturing method using the layered manufacturing device according to the first embodiment of the present invention. [Figure 9]FIG. 1 is an explanatory diagram of a layered manufacturing method using the layered manufacturing device according to the first embodiment of the present invention. [Figure 10] FIG. 10 is a schematic diagram showing a layered manufacturing apparatus according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the additive manufacturing apparatus disclosed in the present application will be described in detail with reference to the accompanying drawings. Note that the embodiments described below are merely examples, and the present invention is not limited to these embodiments.

[0016] Embodiment 1 1 is a schematic diagram showing an additive manufacturing apparatus 100 according to Embodiment 1. As shown in Fig. 1, the additive manufacturing apparatus 100 includes a vacuum chamber 1, an electron gun 2 housed in an electron gun chamber 3 installed above the vacuum chamber 1 and irradiating an electron beam EB, a work base 4 installed in the vacuum chamber 1 and having a manufacturing region R where an additively manufactured object M is manufactured, a powder supply unit 6 that supplies powder material 5, which is the material for the additively manufactured object M, to the manufacturing region R, a shield member 7 that covers at least a portion of the side surface of a passage region S1, which is the region in the vacuum chamber 1 through which the electron beam EB passes, and a gas supply unit 8 that supplies an inert gas into a gas supply space G, which is a space where the side surface of the passage region S1 is covered by the shield member 7. The work platform 4 divides the vacuum chamber 1 in the height direction and has a base portion 4a extending horizontally.

[0017] The vacuum chamber 1 is evacuated by a vacuum device (not shown) and the inside of the vacuum chamber 1 is maintained at a vacuum.

[0018] The electron gun 2 faces the base 4a of the work platform 4 and irradiates an electron beam EB onto a predetermined scanning range. An opening 3b is provided in the floor 3a of the electron gun chamber 3, connecting the electron gun chamber 3 to the vacuum chamber 1, and the electron beam EB emitted from the electron gun 2 is irradiated into the vacuum chamber 1 through the opening 3b. The opening 3b can be opened and closed by a shutter (not shown), and is closed except when the electron beam EB is being irradiated. In other words, the vacuum chamber 1 and the electron gun chamber 3 are isolated from each other except when the electron beam EB is being irradiated, making it possible to maintain the degree of vacuum within the vacuum chamber 1. The electron gun 2 may be installed in the vacuum chamber 1 together with the electron gun chamber 3 while being housed in the electron gun chamber 3 .

[0019] The electron beam EB can be deflected by electromagnetic force to control the irradiation location. The electron beam EB spreads at a predetermined spread angle from the electron gun 2 to the base 4a. In other words, the spread of the electron beam EB is greater toward the base 4a. Generally, the electron beam EB spreads in a conical shape. In the first embodiment, the region through which the path of the electron beam moves when the irradiation target of the electron beam EB moves within the scanning range is defined as the electron beam EB passage region, and the passage region within the vacuum chamber 1 is defined as passage region S1, and the passage region within the electron gun chamber 3 is defined as passage region S2.

[0020] The opening area of ​​the opening 3b is equal to or greater than the horizontal cross-sectional area of ​​the passage region S2 at the height of the floor 3a. Therefore, the electron beam EB enters the vacuum chamber 1 through the opening 3b regardless of the path taken within the passage region S2.

[0021] The work platform 4 has a base 4a with an opening 4b, a work table 41 below the opening 4b whose vertical height can be adjusted by a lifting mechanism 42, and a build plate 43 placed on the work table 41. A build region R is formed on the work platform 4, to which powder material 5, the raw material of the layered object M, is supplied. The build region R is the space between the work table 41 and the opening 4b in the base 4a. The height of the work table 41 can be adjusted by the lifting mechanism 42. The bottom surface of the build region R is formed by the work table 41, and the depth of the build region R is adjusted by raising and lowering the work table 41. The lifting mechanism 42 is, for example, a rack and pinion or a ball screw. The build plate 43 is placed on the work table 41 with the powder material 5 spread all around it, and the layered object M is built on the build plate 43. The build plate 43 is grounded to the work table 41, which is at GND potential, via a GND line (not shown). The build plate 43 is, for example, a metal plate.

[0022] The powder material 5 is a powdered material that solidifies to form the layered object M, and is melted, solidified, or sintered and solidified when irradiated with an electron beam EB from the electron gun 2. The powder material 5 is, for example, a powder material of metal particles such as a cobalt-chromium-molybdenum alloy or a titanium alloy, but is not limited to a powder material of metal particles and may be any material that can be melted, solidified, or sintered when irradiated with an electron beam EB.

[0023] A powder supply unit 6 is installed on the base unit 4a. The powder supply unit 6 has a powder box 61 that stores powder material 5, and a powder bed formation mechanism 62 that spreads the powder material 5 supplied from the powder box 61 over the building region R. The powder box 61 is, for example, a rectangular parallelepiped box, and the powder bed formation mechanism 62 is, for example, a recoater. The powder bed formation mechanism 62 moves above the building region R, supplying a predetermined amount of powder material 5 into the building region R and spreading the powder material 5 over the work table 41. It should be noted that the powder box 61 need not necessarily be provided on the base portion 4a as long as it can supply the powder material 5 to the powder bed forming mechanism 62.

[0024] FIG. 2 is a diagram illustrating an example of the shape of the shield member 7. FIG. 2(a) is an upper perspective view of the shield member 7, and FIG. 2(b) is a lower perspective view of the shield member 7. The shield member 7 is attached to the vacuum chamber by a support mechanism (not shown). The shield member 7 has a shape that covers at least a portion of the side surface of the passage region S1, and is, for example, cylindrical, conical, or quadrangular pyramidal, as shown in FIGS. 2(a) and 2(b), respectively. Here, the irradiation region L shown in FIG. 2 is the region in the printing region R that is irradiated with the electron beam EB.

[0025] 2, the shield member 7 defines therein a gas supply space G, which is a space to which the anti-scattering gas is supplied. The gas supply space G is a space in which the side surface of the passage area S1 is covered by the shield member 7. As shown in FIG. 1, the horizontal cross-sectional area of ​​the gas supply space G in a horizontal plane at a point at an arbitrary height h from the base portion 4a is larger than the horizontal cross-sectional area of ​​the passage area S1 at the point at the height h. The scattering prevention gas is a gas that is ionized by irradiation with the electron beam EB.

[0026] 2, the shield member 7 is provided with an opening 7a on the electron gun 2 side and an opening 7b on the fabrication region R side so that the electron beam EB passes through the gas supply space G and reaches the fabrication region R. The opening areas of the openings 7a and 7b are larger than the horizontal cross-sectional areas of the passage regions S1 in the horizontal planes of the openings 7a and 7b. The shapes of the openings 7a and 7b are, for example, approximately circular or rectangular.

[0027] The shape of the shield member 7 is not limited to the shape shown in Fig. 2 as long as it covers at least a part of the side surface of the passage region S1, which is the region in the vacuum chamber 1 through which the electron beam EB passes. Furthermore, the shape of the openings 7a and 7b of the shield member 7 is not limited to the shape shown in Fig. 2.

[0028] The shield member 7 is made of a metal material such as aluminum or SUS (Steel Use Stainless), for example.

[0029] The gas supply unit 8 supplies the anti-scattering gas at a constant flow rate into the gas supply space G. The gas supply unit 8 has a vacuum pump 81 provided outside the vacuum chamber 1 to reduce the pressure of the anti-scattering gas, a container 82 provided outside the vacuum chamber 1 to hold the anti-scattering gas, a gas inlet 83 provided on the side wall of the vacuum chamber 1, and a gas outlet 84 provided on the base 4a. Furthermore, the constant flow rate at which the gas supply unit 8 supplies the anti-scattering gas into the gas supply space G is significantly smaller than the flow rate exhausted by the vacuum device that maintains the vacuum chamber 1 at a vacuum, and therefore does not affect the maintenance of the vacuum level in the vacuum chamber 1.

[0030] Vacuum pump 81 is connected to container 82 via piping 801 and reduces the pressure of the anti-scattering gas held in container 82. Gas inlet 83 is connected to container 82 via piping 802 and to gas outlet 84 via piping 803. Gas inlet 83 introduces the anti-scattering gas held in container 82 into gas outlet 84. Gas outlet 84 is connected to shield member 7 via piping 804 and supplies the anti-scattering gas to gas supply space G within shield member 7 from gas supply port 8a, which is the connection between shield member 7 and piping 804. The gas supply ports 8a may be provided in multiple locations along the height of the shield member 7 so that the anti-scattering gas can be efficiently supplied into the gas supply space G, or may be provided in multiple locations along the circumferential direction of the shield member 7 so that the anti-scattering gas can be uniformly supplied into the gas supply space G.

[0031] Since the gas supply space G is a space in which the side of the passage area S1 is covered by the shielding member 7, no matter what path the electron beam EB passes through in the passage area S1, the electron beam EB irradiates the anti-scattering gas, and the anti-scattering gas is positively ionized by the irradiation of the electron beam EB. The anti-scattering gas is not particularly limited as long as it is cationized by irradiation with the electron beam EB, but from the viewpoint of preventing oxidation of the powder material 5, it is desirable to use an inert gas such as argon or helium.

[0032] It is desirable that the anti-scattering gas be supplied as a molecular flow to the gas supply space G. By supplying the anti-scattering gas as a molecular flow to the gas supply space G, scattering, which occurs in the case of a viscous flow, is prevented, and the anti-scattering gas can be efficiently supplied into the gas supply space G.

[0033] In the first embodiment, if the inner diameters of the pipe 804 and the gas supply port 8a are defined as D, the Knudsen number K, which is an index indicating whether the flow of the anti-scattering gas is a viscous flow or a molecular flow, is expressed as K=λ / D, where λ is the mean free path of the anti-scattering gas and D is the inner diameter of the pipe 804 and the gas supply port 8a. The Knudsen number K is set by adjusting the mean free path λ and the inner diameter D of the pipe 804 and the gas supply port 8a. The mean free path λ can be adjusted by adjusting the pressure of the anti-scattering gas. When adjusting the inner diameter D of the pipe 804 and the gas supply port 8a to adjust the Knudsen number K, the number of pipes 804 may be increased or decreased to adjust the Knudsen number K. Here, the mean free path refers to the average distance that particles such as molecules or electrons can travel without being hindered by scattering from a scattering source in the kinetic theory of gases. The mean free path λ and the inner diameter D of the pipe 804 and the gas supply port 8a are set so that the Knudsen number K is greater than 0.3, for example.

[0034] The anti-scattering gas supplied to the gas supply space G by the gas supply unit 8 is irradiated with the electron beam EB and is ionized in the gas supply space G above the powder material 5 in the modeling region R, thereby efficiently electrically neutralizing the negatively charged powder material 5 in the modeling region R.

[0035] The additive manufacturing apparatus 100 supplies the anti-scattering gas into the gas supply space G, so there is no need to supply the anti-scattering gas to the entire vacuum chamber 1, and it is possible to reduce the amount of anti-scattering gas supplied by the gas supply unit 8. Because the additive manufacturing apparatus 100 reduces the amount of anti-scattering gas supplied, it is possible to suppress increases in production costs.

[0036] Furthermore, the layered manufacturing apparatus 100 does not need to supply anti-scattering gas to the entire vacuum chamber 1, which prevents an increase in gas molecules inside the vacuum chamber 1 and prevents a decrease in the degree of vacuum in the vacuum chamber 1. Because the layered manufacturing apparatus 100 can prevent a decrease in the degree of vacuum inside the vacuum chamber 1, it can manufacture the layered object M with high accuracy.

[0037] Furthermore, the additive manufacturing apparatus 100 reduces the supply amount of the anti-scattering gas, thereby suppressing a decrease in the energy of the electron beam EB due to collisions between the electron beam EB and gas molecules of the anti-scattering gas. The additive manufacturing apparatus 100 suppresses a decrease in the energy of the electron beam EB and reduces the amount of energy input to the electron beam EB, thereby suppressing an increase in production costs.

[0038] Next, the suppression of a decrease in the temperature of the powder material 5 or the building plate 43 in the building region R by providing the shield member 7 above the building region R will be described.

[0039] Generally, the higher the temperature of the powder material 5 that can be melted, solidified, or sintered by electron beam irradiation, the lower the electrical resistance. In other words, the higher the temperature of the powder material 5, the more conductive the charge becomes, which suppresses charging due to electron beam irradiation and prevents particles of the powder material 5 from repelling each other due to Coulomb force and scattering.

[0040] Therefore, in order to prevent the powder material 5 from scattering, it is desirable to adjust beam parameters such as beam output, beam focus, or beam scanning speed, and irradiate the powder material 5 with a preheating electron beam PB, which has a lower output than the electron beam EB that melts and solidifies the powder material 5, thereby increasing the temperature of the powder material 5 and suppressing charging of the powder material 5.

[0041] In order to prevent the powder material 5 from becoming charged, it is necessary to preheat the powder material 5 to a temperature of several hundred degrees. However, after the powder material 5 is preheated, radiant heat is emitted from the surface of the powder material 5, causing the temperature of the surface of the powder material 5 to drop. If the powder material 5 is irradiated with an electron beam EB that melts and solidifies the powder material 5 when the surface temperature of the powder material 5 has dropped and the electrical resistance of the powder material 5 has not yet dropped sufficiently, the powder material 5 will charge up and scatter. Furthermore, supplying heat so as not to drop the temperature of the powder material 5 will increase production costs.

[0042] On the other hand, the layered manufacturing apparatus 100 according to the first embodiment is provided with a shield member 7 above the manufacturing region R, which covers at least a portion of the side surface of the passage region S1. As shown in FIG. 2 , when the opening area of ​​the opening 7a on the electron gun 2 side is smaller than the opening area of ​​the opening 7b on the manufacturing region R side, the shield member 7 reflects radiant heat emitted from the manufacturing region R toward the manufacturing region R, thereby suppressing a decrease in temperature of the powder material 5 in the manufacturing region R. Specifically, when the shield member 7 has a tapered shape in which the horizontal cross-sectional area of ​​the gas supply space G decreases from the manufacturing region R side toward the electron gun 2 side, the shield member 7 reflects radiant heat emitted from the manufacturing region R toward the manufacturing region R, thereby suppressing a decrease in temperature of the powder material 5 in the manufacturing region R. In addition, if the shaping plate 43 is preheated before the powder material 5 is irradiated with the electron beam EB, the radiant heat emitted from the shaping plate 43 is reflected back to the shaping plate 43, thereby suppressing a decrease in the temperature of the shaping plate 43.

[0043] The surface of the shield member 7 facing the build region R is desirably larger than the irradiation region L, which is the region in the build region R that is irradiated with the electron beam EB. In other words, the area of ​​the surface of the shield member 7 facing the build region R is desirably larger than the horizontal cross-sectional area of ​​the passage region S1 at the height of the base portion 4a. By making the surface of the shield member 7 facing the build region R larger than the irradiation region L, the shield member 7 can efficiently reflect the radiant heat emitted from the build region R back to the build region R.

[0044] The radiant heat emitted from the building region R is reflected back to the building region R by the shield member 7, thereby suppressing a decrease in temperature of the powder material 5 or the building plate 43 in the building region R. Therefore, the additive manufacturing apparatus 100 according to the first embodiment suppresses a decrease in temperature of the powder material 5 or the building plate 43 by using the shield member 7 provided above the building region R, thereby reducing the amount of energy input to the preheating electron beam PB and electron beam EB and suppressing an increase in production costs.

[0045] Next, we will explain how the shield member 7 suppresses the temperature drop of the powder material 5 or the build plate 43 in the build region R. We measured and compared the temperature change of the build plate 43 when the shield member 7 was installed and the build plate 43 was irradiated with the preheating electron beam PB, and when the shield member 7 was not installed and the build plate 43 was irradiated with the preheating electron beam PB. The surface of the shield member 7 facing the printing region R is larger than the irradiation region L and has a shape that covers about 20% of the operation region S1.

[0046] The build plate 43 was irradiated with a preheating electron beam PB whose beam parameters had been adjusted in advance, and the time it took for the temperature of the build plate 43 to reach 850°C was measured. A sheathed thermocouple was attached to the build plate 43, and the temperature of the sheathed thermocouple was measured. The temperature of the sheathed thermocouple was taken as the temperature of the build plate 43.

[0047] When the shield member 7 was not provided, it took 1200 seconds for the temperature of the build plate 43 to reach 850°C, and the temperature rise rate was 0.69°C / sec. When the shield member 7 was provided, it took 640 seconds for the temperature of the build plate 43 to reach 850°C, and the temperature rise rate was 1.21°C / sec.

[0048] Therefore, it was confirmed that by providing the shield member 7, the additive manufacturing device 100 can reflect the radiant heat emitted from the manufacturing area R back to the manufacturing area R, thereby suppressing a decrease in temperature of the powder material 5 or the manufacturing plate 43 within the manufacturing area R.

[0049] Next, the operation of the layered manufacturing apparatus 100 will be described with reference to Fig. 3 to Fig. 9. Fig. 3 to Fig. 9 are explanatory diagrams of an layered manufacturing method using the layered manufacturing apparatus 100 according to embodiment 1. However, in Fig. 3 to Fig. 9, some of the components shown in Fig. 1 are omitted for visibility reasons.

[0050] The vacuum device draws a vacuum inside the vacuum chamber 1 to stabilize the degree of vacuum inside the vacuum chamber 1. Next, as shown in FIG. 3, the height of the work table 41 is adjusted so that the upper surface of the modeling plate 43 is at the same height as the upper surface of the base portion 4a.

[0051] Next, as shown in FIG. 4, the electron gun 2 irradiates the build plate 43 with a preheating electron beam PB, thereby heating the build plate 43. The preheating electron beam PB has its output reduced compared to the electron beam EB that melts and solidifies the powder material 5 by adjusting beam parameters such as beam output, beam focus, and beam scanning speed.

[0052] Next, as shown in FIG. 5, the work table 41 is lowered so that the height from the top surface of the build plate 43 to the top surface of the base portion 4a is equal to the height of one layer of the powder bed 44a. Next, as shown in FIG. 6, the powder supply unit 6 spreads powder material 5 in the build region R on the work table 41 to form the first layer of the powder bed 44a. The first layer of the powder bed 44a is preheated by heat conduction from the heated build plate 43, and its temperature rises. As the temperature of the powder material 5 increases, its electrical resistance decreases, allowing electrical charges to conduct, suppressing charging due to irradiation with the electron beam EB and preventing the powder material 5 from repelling each other due to Coulomb force and scattering.

[0053] Next, as shown in FIG. 7, the gas supply unit 8 sends the anti-scattering gas stored in the container 82 to the gas inlet 83, and supplies the anti-scattering gas to the gas supply space G through the gas outlet 84. The electron gun 2 then irradiates the first powder bed 44a with the electron beam EB according to a preset irradiation pattern, selectively solidifying the powder material 5 in the first powder bed 44a and obtaining the first layer of layered object Ma. The anti-scattering gas supplied by the gas supply unit 8 is irradiated with the electron beam EB and cationized. The cations electrically neutralize the powder material 5 in the first powder bed 44a, which has been negatively charged by the irradiation with the electron beam EB. Once the fabrication of the first layer of layered object Ma is complete, the irradiation with the electron beam EB is stopped.

[0054] Next, as shown in Fig. 8, the work table 41 is lowered so that the height from the top surface of the first powder bed 44a to the top surface of the base part 4a becomes equal to the thickness of the second powder bed 44b. Next, the powder supplying part 6 forms the second powder bed 44b on top of the first powder bed 44a in the same manner as for the first layer. The temperature of the second powder bed 44b rises due to heat conduction from the layered object Ma of the first layer solidified by the electron beam EB. When the second powder bed 44b is heated by thermal conduction from the first-layer additive manufacturing object Ma, the shield member 7 reflects the radiant heat emitted from the second powder bed 44b back to the second powder bed 44b. Because the shield member 7 reflects the radiant heat emitted from the second powder bed 44b back to the second powder bed 44b, a drop in temperature of the second powder bed 44b is prevented, and the second powder bed 44b can be heated efficiently. Therefore, the electrical resistance of the second powder bed 44b is reduced, and the powder material forming the second powder bed 44b is negatively charged by irradiation with the electron beam EB and repels the electron beam EB due to Coulomb force, preventing the powder material 5 from scattering.

[0055] Next, as shown in FIG. 9, the electron gun 2 irradiates the second layer powder bed 44b with an electron beam EB according to a preset irradiation pattern, selectively solidifying the powder material in the second layer powder bed 44b and obtaining a second layer layered object Mb. Before irradiating the second powder bed 44b with the electron beam EB, the second powder bed 44b may be preheated by irradiating it with a preheating electron beam PB.

[0056] For the third and subsequent layers, as in the case of the second layer, the process of stacking powder beds and selectively solidifying the powder beds of each layer is repeated, thereby forming a layered object M on the work base 4.

[0057] The additive manufacturing apparatus according to the first embodiment comprises a vacuum chamber, a work base provided within the vacuum chamber and having a work table whose height can be adjusted vertically and which forms the bottom surface of a manufacturing area for manufacturing an additive object, a powder supply unit which stores powder material as the raw material for the additive object and supplies the powder material to the manufacturing area, an electron gun which irradiates the manufacturing area with an electron beam to solidify the powder material, a shielding member provided within the vacuum chamber and covering at least a portion of the side of a passage area which is an area through which the electron beam passes, and a gas supply unit which supplies gas which is ionized by irradiation with the electron beam into a gas supply space which is a space whose side surface of the passage area is covered by the shielding member.

[0058] With the above-described configuration, the additive manufacturing apparatus 100 according to embodiment 1 can prevent individual powder materials that have been negatively charged by irradiation with an electron beam from repelling each other due to Coulomb force, thereby preventing the powder materials from scattering, while suppressing increases in production costs.

[0059] In addition, the shielding member of the additive manufacturing apparatus according to embodiment 1 has an opening on the electron gun side and an opening on the manufacturing area side through which the electron beam passes through the gas supply space and reaches the manufacturing area, and is characterized in that the opening area of ​​the opening on the electron gun side is smaller than the opening area of ​​the opening on the manufacturing area side.

[0060] The shield member of the layered manufacturing apparatus according to the first embodiment is characterized by having a tapered shape in which the horizontal cross-sectional area of ​​the gas supply space decreases from the manufacturing region side toward the electron gun side.

[0061] Furthermore, the surface of the shield member of the layered manufacturing apparatus according to the first embodiment that faces the manufacturing region is larger than the irradiation region, which is the region in the manufacturing region that is irradiated with the electron beam.

[0062] With the above-described configuration, the additive manufacturing apparatus 100 according to embodiment 1 reflects the radiant heat emitted from the manufacturing area R back to the manufacturing area R, thereby reducing the amount of energy input required for preheating and suppressing increases in production costs.

[0063] The gas supply unit of the layered manufacturing apparatus according to the first embodiment is characterized in that it supplies gas as a molecular flow of gas.

[0064] With the above configuration, the layered manufacturing apparatus 100 according to the first embodiment can reduce the amount of gas supplied, thereby suppressing an increase in production costs.

[0065] The additive manufacturing method according to the first embodiment includes the steps of supplying powder material, which is the raw material of the additive manufacturing object, to a manufacturing area for manufacturing the additive manufacturing object; irradiating the manufacturing area with an electron beam to solidify the powder material; and supplying gas that is ionized by irradiation with the electron beam into a gas supply space, which is a space in which the side of a passing area, through which the electron beam passes, is covered by a shielding member that covers at least a portion of the side of the passing area.

[0066] With the above-described configuration, the additive manufacturing method according to the first embodiment can suppress increases in production costs.

[0067] Embodiment 2 The configuration of an additive manufacturing apparatus 200 according to embodiment 2 of the present invention will be described. Note that descriptions of configurations that are the same as or correspond to those in embodiment 1 will be omitted, and only different parts of the configuration will be described.

[0068] Fig. 10 is a diagram illustrating the configuration of an additive manufacturing apparatus 200 according to embodiment 2. As shown in Fig. 10, the shield member 7 of the additive manufacturing apparatus 200 has an end portion on the electron gun 2 side joined to a surface of the vacuum chamber 1 on the electron gun 2 side.

[0069] By joining the end of the shield member 7 on the electron gun 2 side to the surface of the vacuum chamber 1 on the electron gun 2 side, it is possible to prevent the anti-scattering gas supplied into the gas supply space G from leaking out from the opening 7a on the electron gun 2 side of the shield member 7. Furthermore, by joining the end of the shield member 7 on the electron gun 2 side to the surface of the vacuum chamber 1 on the electron gun 2 side, it is possible to prevent the radiant heat emitted from the printing region R from leaking out from the opening 7a on the electron gun 2 side of the shield member 7.

[0070] The layered manufacturing apparatus according to the second embodiment is characterized in that the electron-side end of the shield member is joined to the electron gun-side surface of the vacuum chamber.

[0071] With the above-described configuration, the additive manufacturing apparatus 200 according to embodiment 2 can prevent individual powder materials that have been negatively charged by irradiation with an electron beam from repelling each other due to Coulomb force, thereby preventing the powder materials from scattering, while suppressing increases in production costs.

[0072] Furthermore, the present invention allows the embodiments and configurations to be combined as appropriate, and allows some configurations to be modified or omitted, without departing from the spirit of the present invention. [Explanation of symbols]

[0073] 100,200 additive manufacturing equipment, 1 vacuum chamber, 2 electron gun, 3 electron gun chamber, 4 work base, 5 powder material, 6 powder supply unit, 7 shield member, 8 gas supply unit, 3a floor portion, 3b opening portion, 4a base portion, 8a gas supply port, 41 work table, 42 lifting mechanism, 43 build plate, 44a, 44b powder bed, 61 powder box, 62 powder bed forming mechanism, 81 vacuum pump, 82 container, 83 gas inlet, 84 gas outlet, 801,802,803,804 Piping, EB,PB electron beam, G gas supply space, L irradiation area, M laminated object, R printing area, S1, S2 passing area.

Claims

1. a vacuum chamber; a work base provided in the vacuum chamber and having a work table whose height can be adjusted in a vertical direction and which forms a bottom surface of a building area for building a layered object; a powder supply unit that stores a powder material that is a raw material for the layered object and supplies the powder material to the modeling area; an electron gun housed in an electron gun chamber having an opening in a floor portion that can be opened and closed during irradiation of the electron beam, the electron gun irradiating the fabrication region with an electron beam that solidifies the powder material; a shield member provided in the vacuum chamber and covering at least a part of a side surface of a passage region through which the electron beam passes; a gas supply unit that supplies a gas that is ionized by irradiation with the electron beam into a gas supply space, which is a space in which a side surface of the passage area is covered with the shielding member; Equipped with the opening communicates the vacuum chamber with the electron gun chamber; An additive manufacturing device characterized by:

2. 2. The additive manufacturing device according to claim 1, wherein the shielding member has an opening on the electron gun side and an opening on the manufacturing region side through which the electron beam passes through the gas supply space and reaches the manufacturing region, and the opening area of ​​the opening on the electron gun side is smaller than the opening area of ​​the opening on the manufacturing region side.

3. The layered manufacturing apparatus according to claim 2 , wherein the shield member has a tapered shape in which a horizontal cross-sectional area of ​​the gas supply space decreases from the manufacturing region side toward the electron gun side.

4. The layered manufacturing apparatus according to claim 3 , wherein a surface of the shield member facing the manufacturing region is larger than an irradiation region in the manufacturing region that is an area irradiated with the electron beam.

5. 5. The layered manufacturing apparatus according to claim 1, wherein an end of the shield member on the electron gun side is joined to a surface of the vacuum chamber on the electron gun side.

6. The layered manufacturing apparatus according to any one of claims 1 to 5, wherein the gas supply unit supplies the gas as a molecular flow of the gas.

7. supplying a powder material serving as a raw material for the layered object to a building region for building the layered object; irradiating the electron beam to the fabrication region to solidify the powder material by an electron gun housed in an electron gun chamber, the electron gun chamber having an opening in its floor that can be opened and closed during electron beam irradiation and that communicates with a vacuum chamber and the electron gun chamber; supplying a gas that is ionized by irradiation with the electron beam into a gas supply space, which is a space in which a side surface of a passage region, through which the electron beam passes, is covered with a shield member that covers at least a part of the side surface of the passage region; An additive manufacturing method comprising:

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