Method for producing mixed powder, apparatus for producing mixed powder, additive manufacturing method, and additive manufacturing apparatus

Abstract

To provide a mixed powder production method and a mixed powder production apparatus which can precisely and swiftly mix plural kinds of powders at a desired mixing ratio, and an additional production method and an additional production apparatus.MEANS FOR SOLVING THE PROBLEM: A mixed powder production method using plural kinds of powders as raw material has: a first step of pumping the plural kinds of powders to a gap space using plural raw material powder feed passages provided per powder; a second step of jetting the pumped plural kinds of powders to the gap space having a cross sectional area larger than the total cross sections (total cross sectional areas) of the plural raw material powder feed passages so as to be mixed to obtain a mixed powder; and a third step of discharging the mixed powder from a discharge port provided at the downstream side of the gap space.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a mixed powder manufacturing method, a mixed powder manufacturing apparatus, an additive manufacturing method, and an additive manufacturing apparatus for manufacturing a mixed powder by mixing a plurality of types of powders. [Background technology]

[0002] In recent years, additive manufacturing methods and additive manufacturing devices have been developed that premix multiple metal powders and then use the mixed metal powder to create a shape. To improve the efficiency and reduce manufacturing time, additive manufacturing devices with a powder mixing function that can quickly mix multiple powders at a desired ratio are needed. For example, Patent Document 1 discloses a technology for controlling the amount of powder supplied. This technology involves providing a branch valve in the supply path leading to the heat source beam irradiation point to distribute the pressure-fed powder to the desired supply amount. The branch valve's opening and closing ratio controls the amount of powder supplied and compensates for the reduced pressure-fed power due to the branching.

[0003] Furthermore, Patent Document 2 discloses a mixing technology for mixing powders, which has a material chamber with a shutter that opens and closes at the bottom, and a mixing chamber provided below it, in which multiple types of materials are stored in each material chamber, and the supply amount of the materials is adjusted by the opening and closing area of the shutter at the bottom so that the materials are mixed in the mixing chamber at a desired mixing ratio. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-125772 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-52129 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0005] However, in Patent Document 1, it is necessary to provide a branch valve and its adjustment and control mechanism for each powder, which makes the device large-scale, and there are problems such as variations in the opening / closing ratio and the actual supply amount due to wear of the branch valve, and powder adhering to the branch valve and clogging the supply flow path, making it difficult to supply mixed powder with the desired mixture ratio.

[0006] Furthermore, in the method of Patent Document 2, the mixing ratio of the materials is controlled by adjusting the opening and closing degree of the shutter, and the materials are mixed by dropping them into a mixing chamber, so it is difficult to quickly achieve a stable mixed state.

[0007] Therefore, an object of the present invention is to provide a mixed powder manufacturing method and apparatus, and an additive manufacturing method and apparatus, which can accurately and quickly mix multiple types of powder in a desired mixing ratio. [Means for solving the problem]

[0008] The present invention is a method for producing a mixed powder using a plurality of types of powder as raw materials, the method comprising: a first step of pressure-feeding the plurality of types of powder by a pressure-feeding gas for each of the plurality of raw material powder supply paths provided for the plurality of types of powder to a gap space in a mixing chamber comprising a container, an insert member disposed in the container and having an outer wall facing the inner wall of the container, a gap space formed between the inner wall of the container and the outer wall of the insert member, and openings connected to the plurality of raw material powder supply paths at an upper portion of the gap space; a second step of ejecting the pressure-fed plurality of types of powder into the gap space to mix them, thereby obtaining a mixed powder; and a third step of discharging the mixed powder from a discharge port provided downstream of the gap space, Raw material This is a mixed powder manufacturing method characterized in that the relationship equations S2 / S1>1, S2 / S3>1, and S1 / S3≧0.9 hold between the sum S1 of the cross-sectional areas of the powder supply paths, the cross-sectional area S2 of the gap space, and the area S3 of the opening of the discharge port.

[0009] The present invention also provides an apparatus for manufacturing a mixed powder using a plurality of types of powder as raw materials, the apparatus comprising: a plurality of raw material powder supply paths provided for the respective powders; a mixing chamber to which the plurality of raw material powder supply paths are connected; and a discharge path having a discharge port for discharging the mixed powder, the mixing chamber comprising: a container; an insert member disposed in the container and having an outer wall facing the inner wall of the container; a gap space formed between the inner wall of the container and the outer wall of the insert member; and openings at an upper portion of the gap space that are connected to the plurality of raw material powder supply paths; the discharge path is connected to a lower portion of the gap space; and the plurality of raw material powder supply paths are connected to a lower portion of the gap space. Raw material This mixed powder manufacturing device is characterized in that the relationship between the sum S1 of the cross-sectional areas of the powder supply paths, the cross-sectional area S2 of the gap space, and the area S3 of the opening of the discharge port satisfies the following equations: S2 / S1>1, S2 / S3>1, and S1 / S3≧0.9.

[0010] Preferably, the surface roughness of the inner wall of the container is an arithmetic mean roughness of Ra 12.5 μm or less, and the surface roughness of the outer wall of the insertion member is an arithmetic mean roughness of Ra 12.5 μm or less.

[0011] The present invention also provides an additive manufacturing apparatus for additive manufacturing using a mixed powder made from a plurality of types of powder as raw materials, the apparatus comprising: a powder supply device provided for each of the plurality of types of powder; a plurality of raw material powder supply paths provided for each of the powders; a mixing chamber to which the plurality of raw material powder supply paths are connected; and a discharge path provided with a discharge port for discharging the mixed powder, the mixing chamber comprising: a container; an insert member disposed in the container and having an outer wall facing the inner wall of the container; a gap space formed between the inner wall of the container and the outer wall of the insert member; and openings at an upper part of the gap space that are connected to the plurality of raw material powder supply paths, the discharge path being connected to a lower part of the gap space, Raw materialIt is characterized in that, among the total cross-sectional area S1 of the powder supply paths, the cross-sectional area S2 of the gap space, and the area S3 of the opening of the discharge port, the relational expressions S2 / S1 > 1, S2 / S3 > 1, and S1 / S3 ≥ 0.9 are satisfied. A manufacturing apparatus for mixed powder, comprising a head portion that irradiates a heat source beam toward a shaping location. The powder supply device is connected to a plurality of raw material powder supply paths provided for each of the powders. The head portion is connected to the discharge path by a mixed powder supply path that conveys the mixed powder. It is an additive manufacturing apparatus.

[0012] Also, the present invention relates to a method of using a plurality of types of powders, using a plurality of raw material powder supply paths provided for each of the plurality of types of powders, and for each of the raw material powder supply paths, by a pressure-feeding gas, a container, an insertion member disposed in the container and having an outer wall facing the inner wall of the container, a gap space formed between the inner wall of the container and the outer wall of the insertion member, and at the upper part of the gap space, each opening connected to the plurality of raw material powder supply paths. A step of pressure-feeding to the gap space in a mixing chamber provided with the above, a step of ejecting and mixing the pressure-fed plurality of types of powders into a space having a cross-sectional area larger than the total cross-sectional area of the plurality of raw material powder supply paths to obtain a mixed powder, a step of discharging the mixed powder from a discharge port provided on the downstream side of the gap space to a mixed powder supply path, and a step of pressure-feeding the mixed powder discharged from the discharge port to a head portion connected to the mixed powder supply path. A step of discharging the mixed powder pressure-fed to the head portion toward a shaping location and melting and solidifying it. Among the total cross-sectional area S1 of the plurality of powder supply paths, the cross-sectional area S2 of the gap space, and the area S3 of the opening of the discharge port, it is an additive manufacturing method characterized in that the relational expressions S2 / S1 > 1, S2 / S3 > 1, and S1 / S3 ≥ 0.9 are satisfied. Gap space to eject and mix to obtain a mixed powder, a step of discharging the mixed powder from a discharge port provided on the downstream side of the gap space to a mixed powder supply path, and the mixed powder discharged from the discharge port Ta He is pressure-fed to a head portion, and a step of discharging the mixed powder pressure-fed to the head portion toward a shaping location and melting and solidifying it. The plurality of Raw material It is an additive manufacturing method characterized in that, among the total cross-sectional area S1 of the powder supply paths, the cross-sectional area S2 of the gap space, and the area S3 of the opening of the discharge port, the relational expressions S2 / S1 > 1, S2 / S3 > 1, and S1 / S3 ≥ 0.9 are satisfied.

Effects of the Invention

[0013] According to the present invention, it is possible to provide a mixed powder manufacturing method and apparatus, as well as an additive manufacturing apparatus and method, which are capable of accurately and quickly mixing multiple types of powder in a desired mixing ratio. [Brief explanation of the drawings]

[0014]

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[0015] Hereinafter, embodiments of an additive manufacturing apparatus and a mixed powder manufacturing apparatus according to the present invention will be described in detail with reference to the drawings. Then, an additive manufacturing method will be described together with a mixed powder manufacturing method. However, the present invention is not limited to the following embodiments. Furthermore, the following description and drawings have been simplified as appropriate for clarity of explanation.

[0016] (First embodiment) <Additive manufacturing equipment> FIG. 1 shows a schematic diagram of an additive manufacturing system 10 including a mixed powder manufacturing apparatus 100. The additive manufacturing apparatus 10 is composed of a plurality of powder supply devices 11 provided for each of a plurality of types of raw material powders (hereinafter simply referred to as powders 40) 40, a mixed powder manufacturing apparatus 100, a powder supply path 12 connecting the powder supply devices 11 and the mixed powder manufacturing apparatus 100, a head unit 14 that irradiates a heat source beam 15 while ejecting the mixed powder 41, and a mixed powder supply path 13 connecting the head unit 14 and the mixed powder manufacturing apparatus 100. Note that, in this embodiment, a case has been described in which a metal deposition method equipped with the head unit 14 is used, but a powder bed method may also be used.

[0017] When the powder bed method is used, for example, the mixed powder 41 is not discharged using the head unit 14, but the mixed powder 41 produced in advance by the mixed powder production apparatus 100 is deposited in a predetermined area (bed), and then the heat source beam 15 is irradiated from the head unit 14 onto the deposited layer to form a solidified layer that is melted and solidified. This operation can be repeated to carry out additive manufacturing.

[0018] [Powder] There are no particular limitations on the type of material for the powder 40 used as raw material. If the particle size of the powder 40 has an average particle size (D50) of approximately 0.1 to 100 μm, the options for the powder supply device 11 can be increased. Here, in the metal deposition method, the average particle size (D50) is 30 to 250 μm, more preferably 60 to 150 μm, in the cumulative distribution curve that shows the relationship between particle size and volume cumulative from the small particle size side, as determined by laser diffraction.

[0019] [Powder feeding device] The powder supplying devices 11 can be installed according to the number of powders 40 to be mixed, and each stores a powder 40. Each powder supplying device 11 is connected to the mixed powder manufacturing apparatus 100 by a powder supply path 12, and is a device that pressure-feeds a predetermined amount of each powder 40 to the mixed powder manufacturing apparatus 100.

[0020] The method of supplying and controlling the powder 40 is not particularly limited, but a disk type can be used. The disk type is a method in which the powder to be supplied is dropped into a groove on a rotating plate (plate) located below the container storing the powder, and the powder is then pressurized into the supply path using a pressurized fluid (pressurized gas). With this method, it is easy to stably control the amount of powder supplied by controlling the rotation speed of the rotating plate. In addition, since the amount of powder supplied can be changed by changing the speed of the rotating plate, the mixing ratio can be quickly changed even during additive manufacturing, allowing additive manufacturing. The medium used for pressure feeding is a pressurized gas 20 such as an inert gas or compressed air.

[0021] Although not shown in FIG. 1, it is preferable to provide a pressure-feed fluid replenishment mechanism in the powder supply path 12 to replenish the pressure-feed fluid in order to compensate for the pressure loss in the powder supply path 12.

[0022] [Head section] The head unit 14 is connected to the mixed powder manufacturing apparatus 100 by a mixed powder supply path 13 that pressure-feeds the mixed powder 41. The head unit 14 is connected to an external control device, and ejects the mixed powder 41 while irradiating it with a heat source beam 15.

[0023] <Mixed powder manufacturing equipment> An apparatus 100 for producing mixed powder according to the present invention will now be described. FIGS. 2 to 4 show an example of the apparatus for producing mixed powder. Here, the apparatus 100 for producing mixed powder is composed of a plurality of powder supply paths 12 provided for each powder 40, a mixing chamber 110 to which the plurality of powder supply paths 12 are connected, and a discharge path 150 for discharging the mixed powder 41. The material of the powder supply path 12 is not particularly limited, but a metal or resin pipe member can be used. From the viewpoints of pressure resistance and abrasion resistance, for example, stainless steel or engineering plastic can be used.

[0024] The mixing chamber 110 has a container 120 and an insertion member 170 disposed within the container 120 and having an outer wall facing the inner wall 121 of the container 120. A gap space 140 is formed between the inner wall 121 of the container 120 and the outer wall 171 of the insertion member 170. At the upper part of the gap space 140, there are respective openings 130 connected to a plurality of powder supply paths 12. On the other hand, at the lower part of the gap space 140, there is a discharge path 150 having a cross-sectional area equal to or smaller than the minimum cross-sectional area of the gap space 140. The discharge path 150 is connected to a discharge port 160. Here, in the present embodiment, one of the features is that the cross-sectional area of the upper part of the gap space 140 is larger than the sum of the cross-sectional areas of the plurality of powder supply paths 12. Note that the cross-sectional area referred to here is the cross-sectional area in a cross-section perpendicular to the direction in which the powder 40 flows, that is, the supply / discharge direction (vertical direction).

[0025] Since the cross-sectional area of the upper part of the gap space 140 is larger than the sum (total cross-sectional area) of the cross-sectional areas of the plurality of powder supply paths 12, even if there is a difference in the supply amount for each powder 40, the powder 40 can be jetted into the gap space 140 without clogging and can be mixed at a desired mixing ratio. Also, with respect to the pressure applied in the powder supply path 12, if the inside of the gap space 140 is maintained in a negative pressure state and a flow is generated that draws the powder 40 into the gap space 140 when the powder 40 is jetted (introduced) from the powder supply path 12 through the opening 130 into the gap space 140, the powder 40 can be jetted into the gap space 140 without clogging.

[0026] By doing so, it contributes to accurately and quickly obtaining the mixed powder 41 with a desired mixing ratio even for a plurality of types of powder 40.

[0027] Also, in order to efficiently mix the mixed powder 41, it is preferable that the powders 40 are jetted so that they can flow smoothly through the gap space 140 without stagnation and do not collide with each other from opposite directions (opposing directions) or directions close to the advancing direction. Specifically, for example, the cross-sectional outline of the gap space 140 when viewed from the direction in which the powder 40 flows, that is, the supply / discharge direction (vertical direction), can be a gap space 140 having an annular shape such as a circular shape or a polygonal shape.

[0028] The configuration of the mixed powder manufacturing apparatus 100 according to the first embodiment of the present invention will be described in detail below with reference to Figures 2 to 4. Figure 2 shows a schematic diagram and a partial cross-sectional view of the mixed powder manufacturing apparatus 100 according to the first embodiment of the present invention. Figure 2(a) is a view of the mixed powder manufacturing apparatus 100 as seen from the direction in which the powder 40 flows, i.e., from the top side, Figure 2(b) is a cross-sectional view at the center position as seen perpendicular to the flow direction of the powder 40, Figure 2(c) is a cross-sectional view as seen from the AA cross section, and Figure 2(d) is a cross-sectional view as seen from the BB cross section.

[0029] Fig. 3 is an enlarged perspective view of the upper part of the mixed powder manufacturing apparatus 100, showing the state in which the powder supply path 12, the opening 130 connected to the powder supply path 12, and the gap space 140 are connected together. Fig. 4 is a schematic diagram showing example shapes (a) and (b) of the gap space 140.

[0030] 2(a) and (b), the mixing chamber 110 includes a container 120, an inserting member 170 disposed in the container 120 and having an outer wall facing an inner wall 121 of the container 120, a gap space 140 formed between the inner wall 121 of the container 120 and the outer wall 171 of the inserting member 170, openings 130 connected to the plurality of powder supply paths 12 at the top of the gap space 140, and a discharge port 160 connected to a discharge path 150 at the bottom of the gap space 140. Each component will be described below.

[0031] [container] From the viewpoints of pressure resistance and abrasion resistance, the container 120 can be made of a metal material, a resin material, a fiber-reinforced resin material, or the like. Among these, a metal material such as stainless steel is preferably used. Furthermore, in order to ensure that the powder 40 flowing through the gap space 140 (described later) is pressure-fed smoothly to the discharge port 160, the smaller the surface roughness of the inner wall 121 of the container 120, the better. Specifically, for example, the arithmetic mean roughness Ra is preferably Ra 12.5 μm or less, more preferably Ra 6.3 μm or less, and even more preferably Ra 1.6 μm or less.

[0032] [Insertion member] The shape of the insertion member 170 will be described later. As for the material, from the viewpoints of pressure resistance and wear resistance, a metal material, a resin material, a fiber-reinforced resin material, etc. can be used. Further, in order for the powder 40 and the mixed powder 41 flowing in the container 120 to be pumped smoothly to the discharge port 160 without delay, the smaller the surface roughness of the inner wall 121 of the container 120, the better. Specifically, for example, the arithmetic mean roughness Ra is preferably Ra12.5 μm or less, more preferably Ra6.3 μm or less, and even more preferably Ra1.6 μm or less.

[0033] [Opening] The opening 130 is an opening for introducing the powder 40 flowing in the powder supply path 12 into the mixing chamber 110. The opening 130 is connected to the upper part of the container 120, and it may be arranged in the same number as or more than the number of the powder supply paths 12. As the arrangement of the opening 130, for example, as shown in FIGS. 2 and 3, a plurality of openings 130 can be arranged at rotationally symmetric positions. Further, for the opening 130 through which the pressure-feeding gas 20 and the powder 40 do not flow, the opening 130 may be sealed as appropriate.

[0034] [Clearance space] The clearance space 140 is a space formed between the inner wall 121 of the container 120 and the outer wall 171 of the insertion member 170 inside the container 120. The upper part is connected to the opening 130, and the lower part is connected to the discharge path 150. Further, as shown in FIGS. 2 and 3, the clearance space 140 is a place where a plurality of types of powders 40 are introduced into one space through the opening 130 connected to each powder supply path 12 provided for each of the plurality of types of powders 40. That is, the clearance space 140 can also be referred to as a mixing space.

[0035] The cross-sectional area of the upper part of the clearance space 140 connected to the opening 130 has a cross-sectional area larger than the total cross-sectional area of the powder supply paths 12. On the other hand, the cross-sectional area of the lower part connected to the discharge path 150 may be equal to or larger than the total cross-sectional area of the powder supply paths 12. Here, the "total cross-sectional area of the powder supply paths 12" means the sum of the cross-sectional areas of the hollow parts of each powder supply path.

[0036] In the case of the gap space 140 having the above-described characteristics, even if there is a difference in the supply amount for each powder 40, the powder 40 can be introduced and mixed into the gap space 140 without clogging. Therefore, even with a plurality of types of powder 40, a mixed powder with a desired mixing ratio can be obtained.

[0037] At this time, since the mixing is performed by the pressure feeding by the pressure feeding gas 20, a mechanical driving force such as a rotating member is not required. For example, the configuration of the present embodiment is suitable even when mixing powders having a density difference of 5 Mg / m 3 or more (1.5 times or more). In a state where the space from the powder supply path 12 through the gap space 140 to the discharge path 150 is in communication, the powder 40 is mixed while flowing, so that a highly uniform mixing can be stably realized.

[0038] Further, it is preferable that the gap space 140 has the maximum cross-sectional area at the upper part connected to the opening 130 and the minimum cross-sectional area at the lower part connected to the discharge path 150. Further, it is preferable that the change in the cross-sectional area changes smoothly. For example, the general shape of the gap space 140 is an inverted conical shape or an inverted polygonal pyramid shape, and it is preferable that the cross-sectional shape of the gap space 140 when viewed perpendicularly to the flowing direction of the powder 40 is smoothly inclined from the upper part to the lower part of the gap space 140.

[0039] Further, as shown in FIGS. 2(c) and (d), it is preferable that the cross-sectional shape of the gap space 140 when viewed from the flowing direction of the powder 40 is annular. By doing so, for example, even if the particle size and specific gravity of the powder 40 are different, it is possible to suppress the powder 40 from dancing in the gap space 140. Further, the powder 40 or the mixed powder 41 can be pressure-fed to the discharge path 150 without clogging in the gap space 140. Further, an effect of suppressing the generation of turbulent flow of the pressure feeding gas 20 can also be expected.

[0040] The gap space 140 is constituted by the inner wall 121 of the container 120 and the outer wall 171 of the inserted member 170. FIGS. 4(a) to (c) are diagrams showing the shape of the gap space 140.

[0041] Figs. 4(a) to 4(c) show the case where the shape of the gap space 140 is an inverted conical shape, and illustrate the case where the angle α when the diameter expands from the apex of the central axis of the cone toward the bottom of the cone is changed. As a specific angle, it may be more than 0° and less than 90°, but in order to gently change the cross-sectional area, about 15° to 60° is preferable. By doing so, when the powder 40 merges in the gap space 140, it can flow toward the discharge port 160 without delay. Note that (a) shows the case where the apex angle is 60°, (b) shows the case where the apex angle is more than 0 and less than 60° (<60°), and (c) shows the case where the apex angle is more than 60° and less than 90° (60° < 90°).

[0042] Here, in Fig. 4(b), by making the angle sharper and elongating the gap space 140 in the flow direction of the powder 40, the powder 40 can flow while sliding down inside the gap space 140. Further, in Fig. 4(c), by making the angle blunter and shortening it in the flow direction of the powder 40, it can be expected to suppress the pressure loss of the pressure-feeding gas 20 that pressure-feeds the powder 40, and it is effective when the number of powders 40 to be mixed is small and pressure-feeding is performed at a low pressure.

[0043] Note that it is also possible to mix in the mixing chamber 110 without using the insertion member 170. By doing so, the mixing chamber 110 can be further miniaturized by the amount corresponding to not inserting the insertion member 170. When it is desired to use the insertion member 170, for example, the flow velocity (flow rate) of the pressure-feeding gas 20 that pressure-feeds the powder 40 may be decreased so that the powder 40 is less likely to fly up.

[0044] [Discharge path] One end of the discharge path 150 is connected to the gap space 140, and the other end is provided with a discharge port 160 that discharges the mixed powder 41 pressure-fed from the gap space 140. Note that the discharge port 160 can also be used as a connection portion when pressure-feeding the mixed powder 41 to a device or the like connected to the mixed powder supply path 13 and arranged further downstream.

[0045] The shape of the discharge path 150 can be equal to or less than, for example, the minimum cross-sectional area of the gap space 140. When it is less than the minimum cross-sectional area of the gap space 140, it is preferable that it does not decrease rapidly from the minimum cross-sectional area of the gap space 140. The opening area of the discharge port 160 can be less than or equal to the cross-sectional area of the discharge path 150. Also, at least one or more discharge ports 160 may be provided, and the discharge path 150 may be branched to provide a plurality of them.

[0046] (Second Embodiment) Figures 4(d) to (f) show a gap space 240, which is another form of the gap space 140 formed by the inner wall 121 of the container 120 and the insertion member 170. The gap space 240 can be formed by the inner wall 221 of the container 220 and the outer wall 271 of the insertion member 270 having a shape facing it, as shown in Figures 4(d) to (f).

[0047] As shown in Figure 4, when viewed perpendicularly to the flow direction of the powder 40, the cross-section may be other than an inverted conical shape, such as the inner wall 221 surface of the container 220 bulging outward toward the outside of the gap space as shown in Figure 4(d), the inner wall 221 surface of the container 220 bulging inward toward the inside of the gap space as shown in Figure 4(e), or having a plurality of angle changes as shown in Figure 4(f).

[0048] (Third Embodiment) A mixing chamber 310 having a container 320 in a form different from the mixing chamber 110 of the first embodiment will be described. The mixing chamber 310 in this embodiment is a mixing chamber 310 including a container 320 formed by combining divided blocks. Figure 5 shows the mixing chamber 310 including the container 320 formed by combining divided blocks.

[0049] The container 320 can be made into the mixing chamber 310 by joining, for example, an upper block 321 having an opening 130, a lower block 322 having a discharge port 160, and an intermediate block 323. More specifically, for example, a columnar hollow portion 331 that penetrates in the thickness direction and forms part of the powder supply path 12 may be formed in the upper block 321, and a columnar hollow portion 332 that penetrates in the thickness direction and constitutes the discharge path 150 may be formed in the lower block 322. The intermediate block 323 may be provided with a funnel-shaped hollow portion 333 that penetrates in the thickness direction and communicates with the columnar hollow portion 331 of the upper block and the columnar hollow portion 332 of the lower block.

[0050] In this way, by making the division, for example, when increasing the number or supply amount of the powder 40, there may be a case where it is desired to increase the volume of the gap space 140 in order to avoid powder collision and fluidization. Even in such a case, a spacer can be inserted between the upper block 321 having the opening 130 and the intermediate block 323 to easily change the volume of the gap space 140. Further, for example, if the position where the inclination of the inner wall 321 of the container 320 changes is set as the division position, the configuration and assembly of the container 320 can be simplified.

[0051] (Fourth Embodiment) (Pressure Supplementing Mechanism) FIG. 6 shows a mixed powder manufacturing apparatus 400 according to another embodiment of the present invention. The mixed powder manufacturing apparatus 400 is different from the mixed powder manufacturing apparatus 100 in that a pressure supplementing mechanism 410 is provided in the discharge path 150.

[0052] The pressure supplementing mechanism 410 is for controlling an increase in the flow rate of the pressure-feeding gas 20 that pressure-feeds the mixed powder 41 when pressure-feeding the mixed powder 41 that has flowed from the gap space 140 to the discharge path 150 to the head portion 14.

[0053] The pressure replenishment mechanism 410 can be disposed between the discharge path 150 and the discharge port 160, in a direction perpendicular to the discharge path 150. The pressure replenishment mechanism 410 can introduce the pressurized gas 20 into the discharge path 150 at any flow rate, and is expected to create a greater negative pressure in the gap space 140 depending on the flow rate of the introduced pressurized gas. It is also expected to pressure-feed the mixed powder 41 to the head portion 14 more smoothly.

[0054] (Fifth embodiment) <Method of manufacturing mixed powder> Next, one embodiment of a mixed powder manufacturing method for obtaining mixed powder 41 by mixing a plurality of types of powders 40 will be described with reference to FIG.

[0055] This embodiment is a method for producing a mixed powder using multiple types of powder as raw materials, and is characterized by comprising: a first step of pressure-feeding the multiple types of powder to a gap space using multiple raw powder supply paths provided for each of the multiple types of powder; a second step of spraying the pressure-fed multiple types of powder into the gap space having a cross-sectional area larger than the sum of the cross-sectional areas of the multiple raw powder supply paths to mix and obtain a mixed powder; and a third step of discharging the mixed powder from a discharge port provided downstream of the gap space. Therefore, as described above, the mixed powder production apparatus 100 is configured so that the sum of the cross-sectional areas of the multiple powder supply paths 12 (total cross-sectional area) is less than the upper cross-sectional area of the gap space 140.

[0056] In the mixed powder manufacturing method of this embodiment, by maintaining a negative pressure state in the gap space 140 relative to the pressure applied to the powder supply path 12, it is expected that when the powder 40 is introduced from the powder supply path 12 into the gap space 140 through the opening 130, a flow that draws the powder 40 into the gap space 140 will be generated. Due to this drawing flow, even if there are differences in the supply amounts of each powder 40, the powder 40 can be introduced and mixed into the gap space 140 without clogging, and therefore a mixed powder of a desired mixing ratio can be accurately and quickly obtained even if multiple types of powder 40 are used.

[0057] Since mixing is carried out by the pressure feeding with the pressure feeding gas 20, it does not require a mechanical driving force such as a rotating member. For example, the configuration of the present embodiment is also suitable when mixing powders having a density difference of 5 Mg / m 3 or more (1.5 times or more). In a state where the space from the powder supply path 12 through the gap space 140 to the discharge path 150 is in communication, the powders 40 are mixed while flowing, so that it is possible to stably realize highly uniform mixing. Hereinafter, it will be described step by step.

[0058] (First step) The first step is a step of pressure feeding a plurality of types of powders 40 to be mixed up to the gap space 140 using a plurality of powder supply paths 12 provided for each powder 40.

[0059] As a method of pressure feeding the powder 40, the pressure feeding gas 20 can be used. As the pressure feeding gas 20, for example, compressed air, an inert gas, etc. can be used, but it is preferable to use an inert gas that can be expected to prevent oxidation, specifically, argon gas or nitrogen gas. The flow rate of the pressure feeding gas can be appropriately changed by the powder supply device 11.

[0060] (Second step) The second step is a step of mixing a plurality of types of powders 40 ejected into the gap space 140 within the gap space 140. At this time, by ejecting into the gap space 140 having a cross-sectional area larger than the total cross-sectional area of the plurality of powder supply paths 12, the powder can be ejected into the gap space 140 without clogging, and a highly uniform mixed powder can be obtained. When ejecting the powder 40 into the gap space 140, it is preferable to eject and mix it into the gap space 140 where the atmospheric pressure is lower than that in the upstream (powder supply path 12). In other words, it may be ejected and mixed into the gap space 140 having a lower pressure, that is, a gap space 140 in a negative pressure region, with respect to the pressure applied to the upstream (powder supply path 12) of the gap space 140.

[0061] Specifically, regarding the relationship between the sum of the cross-sectional areas of the plurality of powder supply paths 12 and the cross-sectional area of the gap space 140, it is sufficient if the ratio (S2 / S1) of the cross-sectional area S2 of the gap space 140 to the sum S1 of the cross-sectional areas of the plurality of powder supply paths 12 exceeds 1, preferably 2 or more, more preferably 20 or more, and even more preferably 50 or more.

[0062] Also, regarding the ratio (S2 / S3) of the cross-sectional area S2 of the gap space 140 to the area (opening area) S3 of the opening of the discharge port 150, it is sufficient if it exceeds 1, preferably 2 or more, more preferably 20 or more, and even more preferably 50 or more. Further, the ratio (S1 / S3) of the sum S1 of the cross-sectional areas of the plurality of powder supply paths 12 to the area S3 of the opening of the discharge port 150 is preferably 0.9 or more, and more preferably 1.2 or more.

[0063] Also, the cross-section of the gap space 140 when viewed from the direction in which the powder 40 flows may be annular. If the gap space 140 is annular, there are expected effects of suppressing the fluttering of the powder 40 jetted into the gap space 140 and suppressing the collision of multiple types of powder 40 from the opposite direction (facing direction) or a direction close to the traveling direction, so that they gradually mix. As a result, the powder 40 can flow smoothly through the gap space 140, and the mixed powder 41 can be efficiently produced. For example, as shown in FIG. 7, a flow 50 in which the powder 40 flows along the shape of the gap space 140 toward the discharge path 150 in the gap space 140 or a flow 51 in which the powder 40 spreads and flows toward the discharge path 150 in the gap space 140 can be formed.

[0064] (Third step) The third step is a step of discharging the mixed powder 41 obtained in the second step through the discharge path 150 provided downstream of the gap space 140 by the discharge port 160. The discharge path 150 is provided with an opening 130 that becomes the discharge port 160 at one end. Also, at least one or more discharge ports 160 may be provided, and the discharge path 150 can be branched and provided in a plurality.

[0065] Further, it is preferable that the cross-sectional area of the gap space 140 gradually decreases toward the discharge port 150. For example, the shape of the gap space 140 is an inverted conical shape or an inverted polygonal pyramid shape, and it is preferable that the cross-sectional shape of the gap space 140 when viewed perpendicularly to the flowing direction of the powder 40 smoothly inclines from the upper part to the lower part of the gap space 140.

[0066] (Seventh Embodiment) <Additive Manufacturing Method> Next, an additive manufacturing method for additive manufacturing using the additive manufacturing apparatus of the present embodiment will be described. The additive manufacturing method using the additive manufacturing apparatus of the present embodiment includes a step A of pumping a plurality of types of powders 40 to the gap space 140 using a plurality of powder supply paths 12 provided for each of the plurality of types of powders 40, and the plurality of types of powders 40 pumped Gap are ejected into a space 140 having a cross-sectional area larger than the total cross-sectional area of the plurality of powder supply paths 12 and mixed to obtain a mixed powder 41, and the mixed powder 41 is discharged from a discharge port 160 provided on the downstream side of the gap space 140 to a mixed powder supply path 13 in a step C, a step D of pumping the mixed powder 41 discharged from the discharge port 160 to a head portion 14 connected to the mixed powder supply path 13, and a step E of discharging the mixed powder 41 pumped to the head portion 14 toward the shaping location 30 and melting and solidifying it, which is one of the features.

[0067] And in the additive manufacturing method for additive manufacturing using the additive manufacturing apparatus of the present embodiment, additive manufacturing can be performed while accurately and quickly mixing a plurality of types of powders at a desired mixing ratio.

[0068] The additive manufacturing method is not particularly limited. For example, a directed energy deposition method such as laser metal deposition, a powder bed method (powder bed melting and bonding method), plasma powder surfacing, etc. can be used. Further, as a heat source for melting the mixed powder 41, the heat source beam 15 can be used, and for example, a laser beam, an electron beam, plasma, an arc, etc. can be used.

[0069] (Example) The following is a detailed description of the example. In this example, the following were used as the mixed powder manufacturing apparatus 100. As the powder supply apparatuses, two TP-Z180111VEFDR manufactured by JEOL Ltd. and two PF2 / 2 manufactured by GTV were used, for a total of four, to mix four types of raw material powders (powder A, powder B, powder C, powder D). The total flow rate of the pressure-feeding gas was set to 6.0 L, and the supply amount of the raw material powder and the flow rate of the pressure-feeding gas were set for each of the four powder supply apparatuses.

[0070] In the mixed powder manufacturing apparatus, resin tubes with an inner diameter of 2.5 mm and an inner diameter of 4 mm were used for the powder supply path, and a member with an inverted conical apex angle of 60° and an arithmetic mean roughness Ra of the outer wall surface of 1.6 μm or less was used for the inserted member. The mixing chamber is provided with an inverted conical inner wall facing the inverted conical inserted member, and is configured by connecting an upper block having four openings with an inner diameter of 2.0 mm, a lower block having a discharge port with a diameter of 6.0 mm, and an intermediate block connecting from the above openings to the above discharge port. As shown in FIG. 5, in the upper block, a columnar hollow portion penetrating in the thickness direction, which forms a part of the powder supply path, and in the lower block, a columnar hollow portion penetrating in the thickness direction, which forms the discharge path, are formed. The intermediate block is provided with a funnel-shaped hollow portion penetrating in the thickness direction, which communicates with the columnar hollow portion of the upper block and the columnar hollow portion of the lower block. Note that for each block, the material was stainless steel (SUS303), and the arithmetic mean roughness Ra of the surface in contact with the raw material powder was 1.6 μm or less.

[0071] Regarding the gap space formed between the inner wall of the container and the outer wall of the inserted member used in this example, the upper end of the gap space had the largest cross-sectional area, and the cross-sectional area S2 was 364 mm 2 There was. On the other hand, the total cross-sectional area (total cross-sectional area) S1 of the powder supply path was (2.5 / 2) 2 × π × 2 (number of ports) + (4 / 2) 2 × π × 2 (number of ports) = 35.0 mm 2 The opening area S3 of the discharge port was 28.3 mm 2, it could be calculated. That is, the ratio (S2 / S1) of the total cross-sectional area S1 of the powder supply path and the cross-sectional area S2 of the gap space was 10, and it was confirmed that the ratio (S2 / S3) of the cross-sectional area S2 of the gap space and the area (opening area) S3 of the opening of the discharge port was 13. Also, the ratio (S1 / S3) of the opening area S3 of the discharge port 150 and the total cross-sectional area S1 of the plurality of powder supply paths 12 was 1.2.

[0072] (Raw material powder and its supply conditions) In this example, four types of raw material powders (hereinafter, powders A to D) shown in Table 1 were prepared.

Table 1

[0073] (Example 1) Using the powder supply devices prepared for each of powders A to D, the supply amounts of powders A to D were set respectively. The respective supply amounts were 6.3 g / min for powder A, 1.2 g / min for powder B, 2.4 g / min for powder C, and 6.0 g / min for powder D (total supply amount of powders A to D: 15.9 g / min). Argon gas was used as the pressure-feeding gas. The supply pressure of the argon gas was kept constant at 0.4 MPa (gauge pressure), and the flow rate of the pressure-feeding gas (argon gas) was set such that powders A and B were 2.0 L / min, and powders C and D were 0.3 L / min.

[0074] (Examples 2 to 4) In addition, as Examples 2 to 4, cases were implemented where the type of the pressure-fed gas, the supply pressure of the pressure-fed gas, and the flow rate of the pressure-fed gas were the same as those in Example 1, and the supply amounts of Powders A to D were changed. In Example 2, the supply amounts of Powders A to D were set as Powder A: 6.3 g / min, Powder B: 1.2 g / min, Powder C: 1.0 g / min, and Powder D: 3.5 g / min, with a total of 12.0 g / min. In Example 3, the supply amounts of Powders A to D were set as Powder A: 1.3 g / min, Powder B: 4.2 g / min, Powder C: 4.5 g / min, and Powder D: 6.0 g / min, with a total of 16.0 g / min. In Example 4, the supply amounts of Powders A to D were set as Powder A: 1.3 g / min, Powder B: 4.2 g / min, Powder C: 3.6 g / min, and Powder D: 3.5 g / min, with a total of 12.6 g / min. The conditions of Examples 1 to 4 are shown in Table 2 above.

[0075] (Comparative Example 1) Also, as a comparative example, two types of Powder C and Powder D were mixed using a one-touch pipe joint KQ2 series reducing double union made by SMC Co., Ltd. (Model: KQ2U04-06A). The relationship of the cross-sectional areas at this time was such that the total cross-sectional area S1 of the powder supply paths was 4π (mm 2 ) × 2 (ports) = 25.1 mm 2 , the cross-sectional area S2 of the confluence part was 7.1 mm 2 , and the area of the opening of the discharge port (opening area) S3 was 28.3 mm 2 . That is, the ratio (S2 / S1) of the total cross-sectional area S1 of the powder supply paths to the cross-sectional area S2 of the confluence part was 0.28, and the ratio (S2 / S3) of the opening area S3 of the discharge port to the cross-sectional area S2 of the confluence part was 0.25. Also, the ratio (S1 / S3) of the opening area S3 of the discharge port 150 to the total cross-sectional area S1 of the plurality of powder supply paths 12 was 0.89.

[0076] The supply amount of Powder C was 2.5 g / min, the supply amount of Powder D was 7.0 g / min, and the total supply amount was 9.5 g / min. Argon gas was used as the pressure-fed gas, the supply pressure was kept constant at 0.4 MPa (gauge pressure), and the flow rate of the argon gas was set such that it was 5.7 L / min for Powder C and 0.3 L / min for Powder D. The conditions of the comparative example are shown in Table 3 above.

[0077] (Method for Evaluating Discharge Amount) In this example, the mixed powder obtained by mixing each powder was discharged from the head portion, and the amount of the mixed powder (hereinafter, total discharge amount) was measured and evaluated. For Examples 1 to 4, specifically, Powders A to D were supplied to a mixed powder manufacturing apparatus and discharged from the head portion. More specifically, Powders A to D were pressure-fed with argon gas from a mixed powder supply apparatus to the mixed powder manufacturing apparatus, mixed in the mixed powder manufacturing apparatus to obtain a mixed powder, the mixed powder was pressure-fed to the head portion, and the mixed powder was discharged toward a measuring container provided below the head portion.

[0078] The total discharge amount was measured by measuring the weight change of the measuring container with a measuring instrument (electronic balance) provided below the measuring container. The measurement period was set to about 0.25 s, and the average value for 100 seconds was measured. The results are shown in Table 2. Further, the measured weight change was differentiated, and a conversion value was obtained from this differentiated value so as to be the supply amount (g / min) per minute. Evaluation was performed with the total discharge amount (g / min) on the vertical axis and the elapsed time (s) on the horizontal axis. Also, the comparative example was measured and evaluated in the same manner.

[0079] (Results) Table 2 shows the measurement results of the total discharge amount for each example, and Table 3 shows the measurement results of Comparative Example 1. Further, FIG. 8 shows the change over time for each sampling period of the total ejection amount of each powder in Example 1, and FIG. 9 shows the change over time for each sampling period of the ejection amount of the powder in Comparative Example 1.

[0080] In Examples 1 to 4, as shown in Table 2 and FIG. 8, the difference between the average value for 100 seconds in the steady state (after 60 s) and the target value was at most 0.6 g, from which it was confirmed that mixing could be performed with high accuracy. Also, the change in the supply amount in the steady state (after 60 s) was within 10% of the supply amount, and a mixed powder having a desired mixing ratio could be obtained even when operating for a long period of time.

[0081] Also, even in the cases of Examples 2 to 4 where the flow rate of argon gas for each powder was kept under the same conditions as in Example 1 and the mixing ratio of Powders A to D was changed, the average value of the total discharge amount was in the vicinity of the total value (target value) of each supply amount. That is, it was confirmed that a mixed powder having a desired mixing ratio could be obtained without being affected by the difference in the properties (such as specific gravity) of the powders. Specifically, powders with a density difference of 5 Mg / m 3 or more (1.5 times or more) could be stably mixed.

[0082] On the other hand, in Comparative Example 1, as shown in Table 3 and Fig. 9, the total discharge amount did not stabilize, and the average value of the total discharge amount over 100 s could not be calculated. Also, a result of a gradually decreasing ejection amount was obtained.

Table 2

Table 3

Explanation of Reference Signs

[0083] 10: Additive manufacturing apparatus 11: Powder supply apparatus 12: Powder supply path 13: Mixed powder supply path 14: Head part 15: Heat source beam 20: Pressure-fed gas 30: Modeling location 40: Powder 41: Mixed powder 50: Flow 51: Flow 100: Apparatus for manufacturing mixed powder 110: Mixing chamber 120: Container 121: Inner wall 130: Opening 140: Gap space 150: Discharge path 160: Discharge port 170: Insertion member 171: Outer wall 220: Container 221: Inner wall 240: Gap space 270: Insertion member 271: Outer wall 310: Mixing chamber 320: Container 321: Upper block 322: Lower block 323: Intermediate block 331: Cylindrical hollow part 332: Cylindrical hollow part 333: Funnel-shaped hollow part 400: Mixed powder manufacturing device 410: Pressure replenishment mechanism

Claims

1. A method for manufacturing a mixed powder using a plurality of types of powders as raw materials, comprising: a first step of feeding the plurality of types of powders, for each of the plurality of types of powders, through a plurality of raw material powder supply paths provided for each of the plurality of types of powders, by a pressure-feeding gas, to a gap space in a mixing chamber provided with a container, an insertion member disposed in the container and having an outer wall facing the inner wall of the container, and an opening provided at an upper portion of the gap space and connected to each of the plurality of raw material powder supply paths; a second step of ejecting and mixing the pressure-fed plurality of types of powders in the gap space to obtain a mixed powder; a third step of discharging the mixed powder from a discharge port provided on the downstream side of the gap space, and a relational expression of S2 / S1 > 1, S2 / S3 > 1, and S1 / S3 ≥ 0.9 is satisfied among the total cross-sectional area S1 of the plurality of raw material powder supply paths, the cross-sectional area S2 of the gap space, and the area S3 of the opening of the discharge port, wherein the method for manufacturing a mixed powder is characterized in that.

2. A manufacturing apparatus for a mixed powder using a plurality of types of powders as raw materials, comprising: a plurality of raw material powder supply paths provided for each of the powders, a mixing chamber to which the plurality of raw material powder supply paths are connected, and a discharge path provided with a discharge port for discharging the mixed powder; wherein the mixing chamber includes: a container; an insertion member disposed in the container and having an outer wall facing the inner wall of the container; a gap space formed between the inner wall of the container and the outer wall of the insertion member; and openings provided at an upper portion of the gap space and connected to each of the plurality of raw material powder supply paths, the discharge path is connected to a lower portion of the gap space, and a relational expression of S2 / S1 > 1, S2 / S3 > 1, and S1 / S3 ≥ 0.9 is satisfied among the total cross-sectional area S1 of the plurality of raw material powder supply paths, the cross-sectional area S2 of the gap space, and the area S3 of the opening of the discharge port. A manufacturing apparatus for a mixed powder, characterized in that.

3. An additive manufacturing apparatus for additive manufacturing using a mixed powder made of a plurality of types of powders as raw materials, comprising: a powder supply device provided for each of the plurality of types of powders; a plurality of raw material powder supply paths provided for each of the powders, a mixing chamber to which the plurality of raw material powder supply paths are connected, and a discharge path provided with a discharge port for discharging the mixed powder; wherein the mixing chamber includes: a container; an insertion member disposed in the container and having an outer wall facing the inner wall of the container; A gap space formed between the inner wall of the container and the outer wall of the inner insertion member, at the upper part of the gap space, each opening connected to the plurality of raw material powder supply paths, the discharge path is connected to the lower part of the gap space, a manufacturing apparatus for mixed powder, characterized in that a relational expression of S2 / S1 > 1, S2 / S3 > 1, and S1 / S3 ≥ 0.9 holds among the total cross-sectional area S1 of the plurality of raw material powder supply paths, the cross-sectional area S2 of the gap space, and the area S3 of the opening of the discharge port, a head unit that irradiates a heat source beam toward a shaping location, the powder supply apparatus is connected to a plurality of raw material powder supply paths provided for each of the powders, the head unit is connected to the discharge path by a mixed powder supply path that conveys the mixed powder, characterized by an additive manufacturing apparatus.

4. A step of pumping a plurality of types of powders to a gap space in a mixing chamber, the mixing chamber including a container, an inner insertion member having an outer wall facing the inner wall of the container and disposed in the container, a gap space formed between the inner wall of the container and the outer wall of the inner insertion member, and at the upper part of the gap space, each opening connected to the plurality of raw material powder supply paths, by using a plurality of raw material powder supply paths provided for each of the plurality of types of powders and by a pressure gas for each of the raw material powder supply paths, a step of ejecting and mixing the pumped plurality of types of powders in the gap space to obtain a mixed powder, a step of discharging the mixed powder from a discharge port provided on the downstream side of the gap space to a mixed powder supply path, a step of pumping the mixed powder discharged from the discharge port to a head unit connected to the mixed powder supply path, a step of discharging the mixed powder pumped to the head unit toward a shaping location and melting and solidifying it, and an additive manufacturing method, characterized in that a relational expression of S2 / S1 > 1, S2 / S3 > 1, and S1 / S3 ≥ 0.9 holds among the total cross-sectional area S1 of the plurality of raw material powder supply paths, the cross-sectional area S2 of the gap space, and the area S3 of the opening of the discharge port.

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