Mixed powder manufacturing device, additive manufacturing method and additive manufacturing device

Abstract

The objective of the present invention is to provide a mixed powder production method, a mixed powder production device, an additive manufacturing method, and an additive manufacturing device, with which a plurality of types of powders can be accurately and quickly mixed in a desired mixing ratio.　This mixed powder production method uses a plurality of types of powders as a raw material, and has: a first step, in which a plurality of raw material powder supply passages, which are provided respectively for each of the plurality of types of powders, are used to pressure-feed the plurality of types of powders to a gap space; a second step, in which the pressure-fed plurality of types of powders are sprayed into the gap space, which has a cross-sectional area larger than the total of the cross-sectional areas (the total cross-sectional area) of the plurality of raw material powder supply passages, thereby mixing the plurality of types of powders and obtaining a mixed powder; and a third step, in which the mixed powder is discharged from a discharge opening provided downstream from the gap space.

Description

[Technical Field]

[0001] The present invention is directed to a method for producing a mixed powder by mixing a plurality of types of powder. Mixed powder manufacturing equipment, The present invention relates to additive manufacturing methods and apparatus. [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 pressurizing the plurality of types of powder to a gap space formed between an inner wall of a container and an outer wall of an inserting member by using a plurality of raw material powder supply paths provided for each of the plurality of types of powder, and a second step of pressurizing the plurality of types of powder to a gap space formed between an inner wall of a container and an outer wall of an inserting member by using a pressurized gas for each of the plurality of raw material powder supply paths; From the raw material powder supply path Negative pressure state And, Within the interstitial space , vertically Let it squirt , by the pressure gas The mixed powder manufacturing method includes a second step of mixing the powder to obtain a mixed powder, and a third step of discharging the mixed powder from a discharge port provided downstream of the gap space.

[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; gap spaces formed between the inner wall of the container and the outer wall of the insert member; and openings at the upper part of the gap spaces connected to the plurality of raw material powder supply paths, the discharge paths being connected to the lower part of the gap spaces, the gap spaces being connected to the openings, the cross-sectional area of ​​the gap spaces being larger than the sum of the cross-sectional areas of the plurality of raw material powder supply paths, The pressure is lower than that of the raw material powder supply path; The plurality of types of powders are pressure-fed to the gap space by a pressure-fed gas through the plurality of raw material powder supply paths. The mixture is jetted vertically into the gap space and mixed by the pressure-feeding gas. The mixed powder manufacturing apparatus is characterized by the above.

[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. The gap space is preferably an annular space that is smoothly inclined and whose cross-sectional area gradually decreases from the top to the bottom. The mixing chamber is preferably formed by combining a plurality of divided blocks divided in the vertical direction. It is preferable to provide a pressure replenishing mechanism in the discharge path between the lower part of the gap space and the discharge port.

[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; gap spaces formed between the inner wall of the container and the outer wall of the insert member; and openings at upper portions of the gap spaces connected to the plurality of raw material powder supply paths, the discharge paths being connected to lower portions of the gap spaces, the gap spaces being connected to the openings, the cross-sectional area of ​​the gap spaces being greater than the sum of the cross-sectional areas of the plurality of raw material powder supply paths, With respect to the raw material powder supply path Maintain negative pressure death The plurality of types of powders are pressure-fed to the gap space by a pressure-fed gas through each of the plurality of raw material powder supply paths, The mixture is sprayed vertically into the gap space and mixed by the pressure-feeding gas. and a head unit that irradiates a heat source beam toward a part to be manufactured, wherein the powder supply device and the mixed powder manufacturing device are connected by a plurality of raw powder supply paths provided for each powder, and the mixed powder manufacturing device and the head unit are connected by a mixed powder supply path that transports the mixed powder.

[0012] The present invention also provides a method for producing a powder having a cross-sectional area larger than the sum of the cross-sectional areas of the plurality of raw material powder supply paths, the method comprising the steps of: using a plurality of raw material powder supply paths provided for each of the plurality of powders; and pressurizing the plurality of powders by a pressurized gas for each of the raw material powder supply paths to a gap space formed between an inner wall of a container and an outer wall of an inserting member; From the raw material powder supply path In the gap space under negative pressure , vertically Let it squirt , by the pressure gasThis is an additive manufacturing method characterized by having the steps of: mixing the powders to obtain a mixed powder; discharging the mixed powder from a discharge port provided downstream of the gap space into a mixed powder supply path; pressure-feeding the mixed powder discharged from the discharge port to the head section connected to the mixed powder supply path; and discharging the mixed powder pressure-feeded to the head section toward a molding location, melting it, and solidifying it. [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] [Figure 1] 1 is a schematic diagram of an additive manufacturing system including a mixed powder manufacturing device in accordance with an embodiment of the present invention; FIG. [Figure 2] 1 is a schematic diagram and a partial cross-sectional view of a mixed powder manufacturing apparatus according to an embodiment of the present invention. [Figure 3] FIG. 2 is an enlarged perspective view of an upper portion of the mixed powder manufacturing apparatus according to the embodiment of the present invention. [Figure 4] 3A to 3F are schematic diagrams showing examples of the shape of a gap space in an embodiment of the present invention. [Figure 5] FIG. 2 is a schematic diagram of a mixing chamber configured from divided blocks in an embodiment of the present invention. [Figure 6] FIG. 2 is a schematic diagram of a pressure refill port in an embodiment of the present invention. [Figure 7] FIG. 1 is a schematic diagram of powder flow before mixing within the interstitial space in an embodiment of the present invention. [Figure 8] 1 shows the change in the total discharge amount by the mixed powder manufacturing apparatus of the example. [Figure 9] 10 shows the change in the total discharge amount by the mixed powder manufacturing apparatus of the comparative example. DETAILED DESCRIPTION OF THE INVENTION

[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 includes a container 120 and an insert member 170 disposed within the container 120, the insert member 170 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 insert member 170. The upper portion of the gap space 140 includes openings 130 connected to the multiple powder supply paths 12. The lower portion of the gap space 140 includes 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. One of the features of this embodiment is that the cross-sectional area of ​​the upper portion of the gap space 140 is larger than the sum of the cross-sectional areas of the multiple powder supply paths 12. The cross-sectional area here refers to the cross-sectional area of ​​a cross section perpendicular to the flow direction of the powder 40, i.e., the supply / discharge direction (vertical direction).

[0025] Because 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 multiple powder supply paths 12, even if there is a difference in the supply amount of each powder 40, the powder 40 can be ejected into the gap space 140 without clogging and mixed at a desired mixing ratio. Furthermore, by maintaining a negative pressure state within the gap space 140 relative to the pressure applied within the powder supply path 12 and generating a flow that draws the powder 40 into the gap space 140 when the powder 40 is ejected (introduced) from the powder supply path 12 through the opening 130 into the gap space 140, the powder 40 can be ejected into the gap space 140 without clogging.

[0026] This contributes to accurately and quickly obtaining mixed powder 41 with a desired mixing ratio even when multiple types of powder 40 are used.

[0027] Furthermore, in order to efficiently mix the mixed powder 41, it is preferable to eject the powders 40 from the directions of their movement (opposite directions) or from directions close to the directions of their movement so as not to collide with each other, allowing the powders 40 to flow smoothly through the gap spaces 140. Specifically, for example, the gap spaces 140 may have a cross section that is roughly circular or polygonal annular when viewed from the direction in which the powders 40 flow, i.e., the supply / discharge direction (vertical direction).

[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 insert 170 will be described later, but the material may be a metal, resin, fiber-reinforced resin, or the like, from the viewpoints of pressure resistance and abrasion resistance. Furthermore, the smaller the surface roughness of the inner wall 121 of the container 120, the better, so that the powder 40 and mixed powder 41 flowing through the container 120 are guided smoothly and without delay to the discharge port 160. 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.

[0033] Opening Openings 130 are openings for introducing powder 40 flowing through powder supply path 12 into mixing chamber 110. Openings 130 are connected to the top of container 120, and the number of openings 130 may be equal to or greater than the number of powder supply paths 12. As shown in FIGS. 2 and 3, for example, multiple openings 130 may be arranged in rotationally symmetrical positions. Furthermore, openings 130 that do not allow the flow of pressurized gas 20 and powder 40 may be appropriately sealed.

[0034] [Gap space] The gap space 140 is a space formed within the container 120 between the inner wall 121 of the container 120 and the outer wall 171 of the inserting member 170, and is connected at its upper part to the opening 130 and at its lower part to the discharge path 150. As shown in FIGS. 2 and 3 , the gap space 140 is a space where multiple types of powders 40 are introduced into one space through the openings 130 connected to the powder supply paths 12 provided for each type of powder 40. In other words, the gap space 140 can also be referred to as a mixing space.

[0035] The cross-sectional area of ​​the upper part of gap space 140 connected to opening 130 is larger than the total cross-sectional area of ​​powder supply paths 12. On the other hand, the cross-sectional area of ​​the lower part connected to discharge path 150 may be equal to or larger than the total cross-sectional area of ​​powder supply paths 12. Note that the "total cross-sectional area of ​​powder supply paths 12" here refers to the sum of the cross-sectional areas of the hollow portions of each powder supply path.

[0036] If the gap space 140 has the characteristics described above, even if there are differences in the supply amount of each powder 40, the powder 40 can be introduced and mixed into the gap space 140 without clogging, so even if there are multiple types of powder 40, a mixed powder with the desired mixing ratio can be obtained.

[0037] At this time, mixing is performed by pressure feeding using the pressure gas 20, so no mechanical driving force such as a rotating member is required. For example, in the configuration of this embodiment, 3This is also suitable for mixing powders that are different in size by 1.5 times or more (1.5 times or more). Since the spaces from the powder supply path 12 through the gap space 140 to the discharge path 150 are connected, the powders 40 are mixed while flowing, making it possible to stably achieve highly uniform mixing.

[0038] Furthermore, it is preferable that the cross-sectional area of ​​the gap space 140 is largest at the upper portion connected to the opening 130 and smallest at the lower portion connected to the discharge path 150. It is also preferable that the cross-sectional area changes smoothly. For example, it is preferable that the general shape of the gap space 140 is an inverted cone or an inverted polygonal pyramid, and that the cross-sectional shape of the gap space 140 when viewed perpendicular to the flow direction of the powder 40 slopes smoothly from the top to the bottom of the gap space 140.

[0039] 2(c) and 2(d), the cross-sectional shape of the gap space 140 as viewed from the direction in which the powder 40 flows is preferably annular. This can prevent the powder 40 from floating around in the gap space 140, even if the powder 40 has different particle sizes or specific gravities. Furthermore, the powder 40 or the mixed powder 41 can be pumped to the discharge path 150 without clogging the gap space 140. Another expected effect is that the generation of turbulence in the pumped gas 20 can be suppressed.

[0040] The gap space 140 is defined by the inner wall 121 of the container 120 and the outer wall 171 of the insertion member 170. FIGS.

[0041] 4(a) to 4(c) show examples in which the gap space 140 has an inverted conical shape, with the angle α of the cone expanding from the apex of the central axis toward the base of the cone being varied. A specific angle α may be greater than 0° and less than 90°, but a value of approximately 15° to 60° is preferred to ensure a gradual change in cross-sectional area. This allows the powder 40 to flow toward the discharge port 160 without delay when joining together in the gap space 140. (a) shows the case where the apex angle is 60°, (b) shows the case where the apex angle is greater than 0° and less than 60° (<60°), and (c) shows the case where the apex angle is greater than 60° and less than 90° (60°<90°).

[0042] 4(b), the angle is made more acute and the gap space 140 is extended in the flow direction of the powder 40, allowing the powder 40 to slide down and flow within the gap space 140. In addition, FIG. 4(c) shows that the angle is made more obtuse and shortened in the flow direction of the powder 40, which is expected to reduce the pressure loss of the pumping gas 20 that pumps the powder 40, and is effective when the number of powders 40 to be mixed is small and the powders 40 are pumped at low pressure.

[0043] 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 made even smaller by the amount of insertion member 170 not being inserted. When using the insertion member 170, it is possible to make the powder 40 less likely to fly up by, for example, reducing the flow rate (flow rate) of the compression gas 20 that compresses and feeds the powder 40.

[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. The discharge port 160 can also be connected to the mixed powder supply path 13 and used as a connecting part when pressure-fed the mixed powder 41 to a device or the like disposed further downstream.

[0045] The shape of the discharge path 150 can be, for example, equal to or smaller than the minimum cross-sectional area of ​​the gap space 140. When the shape is set to be equal to or smaller than the minimum cross-sectional area of ​​the gap space 140, it is preferable that the area does not decrease sharply from the minimum cross-sectional area of ​​the gap space 140. The opening area of ​​the discharge port 160 can be set to be equal to or smaller than the cross-sectional area of ​​the discharge path 150. Furthermore, it is sufficient to provide at least one discharge port 160, and multiple discharge ports 160 can also be provided by branching the discharge path 150.

[0046] (Second embodiment) 4(d) to (f) show a gap space 240, which is another form of the gap space 140 formed between 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 the inner wall 221, as shown in FIGS.

[0047] As shown in Figure 4, the cross section when viewed perpendicularly to the flow direction of the powder 40 may have a shape other than an inverted cone shape, such as one in which the inner wall 221 surface of the container 220 is convex toward the outside of the void space as shown in Figure 4(d), one in which the inner wall 221 surface of the container 220 is convex toward the inside of the void space as shown in Figure 4(e), or one with multiple angle changes as shown in Figure 4(f).

[0048] (Third embodiment) A mixing chamber 310 having a container 320 with a different shape from the mixing chamber 110 of the first embodiment will be described. The mixing chamber 310 in this embodiment is a mixing chamber 310 equipped with a container 320 configured by combining divided blocks. Fig. 5 shows the mixing chamber 310 equipped with a container 320 configured by combining divided blocks.

[0049] The container 320 may be divided into an upper block 321 having the opening 130, a lower block 322 having the discharge port 160, and an intermediate block 323, and these blocks may be joined together to form the mixing chamber 310. More specifically, for example, the upper block 321 may be formed with a cylindrical hollow portion 331 that penetrates through the thickness direction and forms part of the powder supply path 12, and the lower block 322 may be formed with a cylindrical hollow portion 332 that penetrates through the thickness direction and forms the discharge path 150. The intermediate block 323 may be formed with a funnel-shaped hollow portion 333 that penetrates through the thickness direction and communicates with the cylindrical hollow portion 331 of the upper block and the cylindrical hollow portion 332 of the lower block.

[0050] By dividing the container 320 in this manner, for example, when the number or supply amount of powder 40 is increased, it may be necessary to increase the capacity of the gap space 140 to avoid collisions or turbulence of the powder. Even in such a case, the volume of the gap space 140 can be easily changed by inserting a spacer between the upper block 321 having the opening 130 and the middle block 323. Furthermore, for example, if the position where the inclination of the inner wall 321 of the container 320 changes is set as the dividing position, the configuration and assembly of the container 320 can be simplified.

[0051] (Fourth embodiment) (Pressure replenishment mechanism) 6 shows a mixed powder manufacturing apparatus 400 according to another embodiment of the present invention. The mixed powder manufacturing apparatus 400 differs from the mixed powder manufacturing apparatus 100 in that a pressure replenishment mechanism 410 is provided in the discharge passage 150.

[0052] The pressure replenishment mechanism 410 is used to increase and control the flow rate of the pressure-feeding gas 20 that pressurizes the mixed powder 41 when the mixed powder 41 that has flowed from the gap space 140 to the discharge path 150 is pressurized 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 performed by pressure feeding using the pressure gas 20, no mechanical driving force such as a rotating member is required. For example, the configuration of this embodiment is a mixture of 10 ... 3 This method is also suitable for mixing powders that are different in size by more than 1.5 times (1.5 times or more). Since the powders 40 flow and are mixed in a state in which the space from the powder supply path 12 through the gap space 140 to the discharge path 150 is connected, it is possible to stably achieve highly uniform mixing. Each step will be explained below.

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

[0059] The powder 40 can be pressure-fed using a pressure-fed gas 20. For example, compressed air or an inert gas can be used as the pressure-fed gas 20. However, it is preferable to use an inert gas, such as argon gas or nitrogen gas, which is expected to prevent oxidation. The flow rate of the pressure-fed gas can be appropriately changed by the powder supplying device 11.

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

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

[0062] Furthermore, 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 may be greater than 1, and is preferably 2 or more, more preferably 20 or more, and even more preferably 50 or more. Furthermore, the ratio (S1 / S3) of the total cross-sectional area S1 of the multiple 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] Furthermore, the cross section of the gap space 140 when viewed from the direction in which the powder 40 flows may be annular. The annular gap space 140 is expected to have the effect of suppressing the powder 40 ejected into the gap space 140 from flying up and suppressing collisions between multiple types of powder 40 from the direction of their mutual movement (opposing direction) or from a direction close to the direction of their movement, thereby gradually mixing them together. This allows the powder 40 to flow smoothly within the gap space 140, allowing the mixed powder 41 to be produced efficiently. For example, as shown in FIG. 7 , a flow 50 in which the powder 40 flows through the gap space 140 toward the discharge path 150, following the shape of the gap space 140, or a flow 51 in which the powder 40 flows while spreading through the gap space 140 toward the discharge path 150 can be formed.

[0064] (Third step) The third step is a step of discharging the mixed powder 41 obtained in the second step through a discharge path 150 provided downstream of the gap space 140 and from a discharge port 160. The discharge path 150 has an opening 130 at one end that becomes the discharge port 160. It is sufficient to provide at least one discharge port 160, and multiple discharge ports 160 can be provided by branching the discharge path 150.

[0065] It is also preferable that the cross-sectional area of ​​the gap space 140 gradually decreases toward the discharge port 150. For example, it is preferable that the shape of the gap space 140 is an inverted cone or an inverted polygonal pyramid, and that the cross-sectional shape of the gap space 140 when viewed perpendicular to the flow direction of the powder 40 smoothly slopes from the top to the bottom of the gap space 140.

[0066] (Seventh embodiment) <Additive manufacturing method> Next, an additive manufacturing method for additive manufacturing using the additive manufacturing device of this embodiment will be described. The additive manufacturing method using the additive manufacturing apparatus of this embodiment is characterized by having the following steps: step A: pressurizing multiple types of powders 40 to a gap space 140 using multiple powder supply paths 12 provided for each of the multiple types of powders 40; step B: spraying the pressurized multiple types of powders 40 into a gap space 140 having a cross-sectional area larger than the sum of the cross-sectional areas of the multiple powder supply paths 12 and mixing them to obtain a mixed powder 41; step C: ejecting the mixed powder 41 from an outlet 160 provided downstream of the gap space 140 into the mixed powder supply path 13; step D: pressurizing the mixed powder 41 ejected from the outlet 160 to a head portion 14 connected to the mixed powder supply path 13; and step E: ejecting the mixed powder 41 pressurized to the head portion 14 toward the modeling location 30, melting and solidifying it.

[0067] Furthermore, in an additive manufacturing method using the additive manufacturing apparatus of this embodiment, additive manufacturing can be performed while accurately and quickly mixing multiple types of powder in a desired mixing ratio.

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

[0069] (Example) An example will be described in detail below. In this example, the following mixed powder manufacturing apparatus 100 was used. A total of four powder supplying apparatuses were used: two TP-Z180111VEFDRs manufactured by JEOL Ltd. and two PF2 / 2s manufactured by GTV, to mix four types of raw material powders (powder A, powder B, powder C, and powder D). The total flow rate of the compressed gas was set to 6.0 L, and the amount of raw material powder supplied and the flow rate of the compressed gas were set for each of the four powder supplying apparatuses.

[0070] The mixed powder manufacturing equipment used resin tubes with inner diameters of 2.5 mm and 4 mm as the powder supply paths, and the inserting member was an inverted cone with an apex angle of 60° and an outer wall surface with an arithmetic mean roughness Ra of 1.6 μm or less. The mixing chamber had an inverted cone-shaped inner wall facing the inverted cone-shaped insert. It was composed of an upper block with four openings with an inner diameter of 2.0 mm, a lower block with a discharge port with a diameter of 6.0 mm, and an intermediate block connecting the openings to the discharge port. As shown in Figure 5, the upper block had a cylindrical hollow portion that penetrated through its thickness and formed part of the powder supply path, and the lower block had a cylindrical hollow portion that penetrated through its thickness and formed the discharge path. The intermediate block had a funnel-shaped hollow portion that penetrated through its thickness and communicated with the cylindrical hollow portions of the upper block and the lower block. Each block was made of stainless steel (SUS303), with an arithmetic mean roughness (Ra) of 1.6 μm or less on the surface that came into contact with the raw powder.

[0071] In this example, the gap formed by the inner wall of the container and the outer wall of the insert member has the largest cross-sectional area at the top of the gap, and the cross-sectional area S2 is 364 mm 2 On the other hand, the total cross-sectional area of ​​the powder supply path (total cross-sectional area) S1 is (2.5 / 2) 2 ×π×2(number of units)+(4 / 2) 2 ×π×2(number of holes)=35.0mm 2 , the opening area S3 of the outlet is 28.3 mm 2That is, it was confirmed that the ratio (S2 / S1) of the sum of the cross-sectional areas of the powder supply paths S1 to the cross-sectional area S2 of the gap space was 10, and the ratio (S2 / S3) of the area (opening area) S3 of the opening of the discharge port to the cross-sectional area S2 of the gap space was 13. In addition, the ratio (S1 / S3) of the opening area S3 of the discharge port 150 to the sum of the cross-sectional areas S1 of the multiple powder supply paths 12 was 1.2.

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

[0073] Example 1 The supply rates of powders A to D were set using powder supply devices prepared for each powder. The respective supply rates 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 rate for powders A to D: 15.9 g / min). Argon gas was used as the compressed gas. The supply pressure of the argon gas was kept constant at 0.4 MPa (gauge pressure), and the flow rate of the compressed gas (argon gas) was set to 2.0 L / min for powders A and B, and 0.3 L / min for powders C and D.

[0074] Examples 2 to 4 Additionally, in Examples 2 to 4, the type of compressed gas, the supply pressure of the compressed gas, and the flow rate of the compressed gas were kept the same as in Example 1, but the supply rates of Powders A to D were changed. In Example 2, the supply rates of Powders A to D were 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, for a total of 12.0 g / min. In Example 3, the supply rates of Powders A to D were 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, for a total of 16.0 g / min. In Example 4, the supply rates of Powders A to D were 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, for a total of 12.6 g / min. The conditions for Examples 1 to 4 are shown in Table 2.

[0075] (Comparative Example 1) As a comparative example, two types of powders, C and D, were mixed using a one-touch pipe fitting, KQ2 series, different diameter double union Y (model: KQ2U04-06A) manufactured by SMC Corporation. The cross-sectional area relationship at this time was such that the total cross-sectional area S1 of the powder supply path was 4π (mm 2 )×2(mouth)=25.1mm 2 , the cross-sectional area S2 of the confluence is 7.1 mm 2 The area of ​​the outlet opening (opening area) S3 is 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 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 was 0.25. In addition, the ratio (S1 / S3) of the opening area S3 of the discharge port 150 to the total cross-sectional area S1 of the multiple powder supply paths 12 was 0.89.

[0076] The supply rate of Powder C was 2.5 g / min, and the supply rate of Powder D was 7.0 g / min, for a total supply rate of 9.5 g / min. Argon gas was used as the compressed gas, and the supply pressure was constant at 0.4 MPa (gauge pressure). The flow rates of the argon gas were set to 5.7 L / min for Powder C and 0.3 L / min for Powder D. The conditions for the comparative example are shown in Table 3.

[0077] (Method for evaluating discharge volume) In the present examples, a mixed powder obtained by mixing the powders was discharged from the head, and the amount of the mixed powder (hereinafter referred to as the total discharged amount) was measured and evaluated. Specifically, for Examples 1 to 4, powders A to D were supplied to a mixed powder manufacturing apparatus and discharged from the head. More specifically, powders A to D were pumped from the mixed powder supply apparatus to the mixed powder manufacturing apparatus using argon gas, then mixed in the mixed powder manufacturing apparatus to form a mixed powder, which was then pumped to the head and discharged toward a measuring container provided below the head.

[0078] The total discharge amount was determined by measuring the weight change of the measuring container using a measuring device (electronic balance) installed below the measuring container. The measurement cycle was approximately 0.25 seconds, and the average value was measured over 100 seconds. The results are shown in Table 2. Furthermore, the measured weight change was subtracted, and a conversion value was obtained from this subtraction value to obtain the supply amount per minute (g / min), and evaluation was performed with the total discharge amount (g / min) on the vertical axis and the elapsed time (s) on the horizontal axis. Similar measurements and evaluations were also performed on the comparative example.

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

[0080] In Examples 1 to 4, as shown in Table 2 and Figure 8, the difference between the average value over 100 seconds in the steady state (after 60 seconds) and the target value was a maximum of 0.6 g, confirming that mixing was achieved with high precision. Furthermore, the change in the supply amount in the steady state (after 60 seconds) was also within 10% of the supply amount, and mixed powder with the desired mixing ratio could be obtained even in long-term operation.

[0081] Furthermore, in Examples 2 to 4, in which the mixing ratio of powders A to D was changed while the argon gas flow rate for each powder was kept the same as in Example 1, it was confirmed that the average total discharge rate was close to the total value (target value) of each supply rate, that is, it was possible to obtain a mixed powder with the desired mixing ratio without being affected by differences in the properties of the powders (specific gravity, etc.). Specifically, 3 It was confirmed that powders with different ratios (1.5 times or more) could be stably mixed.

[0082] On the other hand, in Comparative Example 1, the total ejection amount did not stabilize, and the average value of the total ejection amount over 100 seconds could not be calculated, as shown in Table 3 and Fig. 9. In addition, the ejection amount gradually decreased. [Table 2] [Table 3] [Explanation of symbols]

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

Claims

1. An apparatus for manufacturing a mixed powder using multiple types of powder as raw materials, 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 comprises: A container and an insert member disposed within the container and having an outer wall facing an inner wall of the container; a gap space formed between an inner wall of the container and an outer wall of the insert; and openings connected to the plurality of raw material powder supply paths at an upper portion of the gap space, The discharge passage is connected to a lower portion of the gap space, the gap space is connected to the opening, and a cross-sectional area of ​​the gap space is larger than a sum of cross-sectional areas of the plurality of raw material powder supply paths, and the gap space is in a negative pressure state compared to the raw material powder supply paths; The surface roughness of the inner wall of the container is an arithmetic mean roughness Ra of 12.5 μm or less, The surface roughness of the outer wall of the insert member is an arithmetic mean roughness Ra of 12.5 μm or less, The mixed powder manufacturing apparatus is characterized in that the multiple types of powders are pressurized by a pressurized gas to the gap space for each of the multiple raw material powder supply paths, and are sprayed vertically into the gap space, and are mixed by pressurization by the pressurized gas without mechanical driving force.

2. A mixed powder manufacturing apparatus as described in Claim 1, characterized in that the mixing chamber is composed of a combination of multiple divided blocks divided in the vertical direction.

3. A mixed powder manufacturing apparatus as described in either claim 1 or 2, characterized in that a pressure replenishment mechanism is provided in the discharge path between the lower part of the gap space and the discharge outlet.

4. An additive manufacturing apparatus for additive manufacturing using a mixed powder made from multiple types of powders, a powder supplying device provided for each of the plurality of types of powder; 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 comprises: A container and an insert member disposed within the container and having an outer wall facing an inner wall of the container; a gap space formed between an inner wall of the container and an outer wall of the insert; and openings connected to the plurality of raw material powder supply paths at an upper portion of the gap space, The discharge passage is connected to a lower portion of the gap space, the gap space is connected to the opening, and a cross-sectional area of ​​the gap space is larger than a sum of cross-sectional areas of the plurality of raw material powder supply paths, and a negative pressure state is maintained with respect to the raw material powder supply paths; a mixed powder manufacturing apparatus in which the plurality of types of powders are pressure-fed to the gap space by a pressure gas through the plurality of raw material powder supply paths, and are ejected vertically into the gap space, and mixed by pressure-fed by the pressure gas without mechanical driving force to produce a mixed powder; a head unit that irradiates a heat source beam toward a target object, the powder supplying device and the mixed powder manufacturing device are connected by a plurality of raw material powder supply paths provided for each of the powders; The mixed powder manufacturing device and the head unit are connected by a mixed powder supply path that transports the mixed powder. An additive manufacturing device characterized by:

5. An additive manufacturing apparatus as described in Claim 4, characterized in that the mixing chamber is made up of a combination of multiple divided blocks divided in the vertical direction.

6. An additive manufacturing apparatus as described in claim 4 or 5, characterized in that a pressure replenishment mechanism is provided in the discharge path between the lower part of the gap space and the discharge outlet.

7. A process of using a plurality of raw powder supply paths provided for each of the plurality of types of powder to pressure-feed a plurality of types of powder with a pressurized gas for each of the raw powder supply paths 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 respective openings at the top of the gap space that are connected to the plurality of raw powder supply paths; a step of vertically ejecting the pressure-fed multiple types of powders into the gap space, which has a cross-sectional area larger than the sum of the cross-sectional areas of the multiple raw material powder supply paths and is in a negative pressure state relative to the raw material powder supply paths, and mixing the multiple types of powders by pressure-fed by the pressure-fed gas without mechanical driving force, thereby obtaining a mixed powder; a step of pressure-feeding the mixed powder discharged from the discharge port to a head portion connected to a mixed powder supply path; a step of discharging the mixed powder pressure-fed to the head portion toward a shaping location, melting and solidifying the mixed powder; 1. An additive manufacturing method comprising:

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