JP2018172739A - Mold material for use in powder laminate molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold material that is improved in fluidity for favorable supply even if supplied from a storage tank of a fall-supply type.SOLUTION: A mold material is provided for use in powder laminate molding. The mold material contains a powder consisting of at least one selected from a group consisting of a metal material and an inorganic material. The integrated mass of a particle having a particle size exceeding 45 μm accounts for 0.5 mass% or greater, and the number of particles having a particle size of 20 μm or smaller based on electron microscope observation is 15 number-of-particles% or smaller.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a modeling material for use in powder additive manufacturing.

  Additive manufacturing (also referred to as three-dimensional modeling) means creating an object from a numerical representation of a three-dimensional shape (typically three-dimensional CAD data) by attaching additive manufacturing materials. Defined as a process that has become rapidly popular in recent years. As one method of this additional manufacturing, powder material is spread in a thin layer, then joined or sintered into a shape corresponding to the cross-section of the object to be shaped, and the thin layers are sequentially stacked together Laminated modeling is known. In this powder additive manufacturing, modeling of resin products using a resin material has been widely performed so far because of its ease of handling. However, in recent years, the need for rapid prototyping that directly forms a member made of metal or cermet using a powder material containing a metal or cermet other than a resin material without the need for a molding die is expanding. Therefore, materials for modeling having various compositions made of metal, ceramics, cermet, and the like are provided (see, for example, Patent Documents 1 and 2).

  On the other hand, an apparatus for powder additive manufacturing typically has a storage tank for storing powder material, a modeling tank in which powder material is supplied and modeling is performed, and transfer and flattening of the powder material. With squeegee to do. In the conventional powder additive manufacturing apparatus, the bottom part of the modeling tank is generally configured by a modeling table that can be moved up and down, and a storage tank for storing the powder material is provided adjacent to the side of the modeling tank. Then, the powder material is pushed out from the storage tank by raising the bottom of the storage tank, and the extruded powder material is transferred to the modeling tank by a squeegee, and leveled flat, thereby forming a thin layer of the powder material on the modeling table. prepare. In order to increase modeling accuracy in powder additive manufacturing, it is necessary to spread the powder material uniformly and uniformly, and to make the surface flat, and the powder material is required to have good fluidity.

JP 2001-152204 A Japanese Patent Laid-Open No. 2006-029194 JP 2007-216595 A

  Recently, for the purpose of increasing the modeling speed and reducing the installation area of the modeling device, a storage tank is provided above the modeling tank, and the powder material is gravity dropped from the lower part of the modeling tank and supplied to the modeling tank. A powder additive manufacturing apparatus is provided (for example, Patent Document 3). In this type of powder additive manufacturing apparatus, for example, the storage tank and the modeling tank are configured to be relatively movable in the horizontal direction. The powder material is dropped while the modeling tank moves above the storage tank, and the dropped powder material is flattened by a squeegee. The thickness of the thin layer of the powder material is as thin as, for example, about 30 to 100 μm, and the supply port of the powder material provided at the lower portion of the storage tank is relatively narrow so that the powder material can be supplied little by little. Therefore, if the powder supply material used in the conventional extrusion supply type additive manufacturing device is used in the drop supply type additive manufacturing device as it is, the supply port may become clogged or the supply amount may be reduced. An unprecedented new problem that unevenness is likely to occur has occurred. In addition, problems such as clogging are more likely to be manifested as the frequency of reusing a powder material that has been repeatedly modeled and did not contribute to modeling increases. Furthermore, if unevenness occurs in the supply amount of the powder material from the storage tank and it is not constant, even if the powder material is leveled by the squeegee, unevenness occurs in the thin layer, and it is inevitable that the modeling accuracy is reduced. There was also.

  The present invention has been made in view of such points, and its purpose is, for example, the fluidity is improved so that the supply can be satisfactorily performed even when supplied from a drop supply storage tank. The object is to provide a powdery modeling material for use in powder additive manufacturing.

  As a technique for solving the above problems, the technology disclosed herein provides a modeling material used for powder additive manufacturing. The modeling material includes a powder made of at least one selected from the group consisting of a metal material and an inorganic material, and an accumulated mass of particles having a particle diameter exceeding 45 μm is 0.5 mass% or more of the whole, The number of particles having a particle diameter of 20 μm or less based on microscopic observation is 15% by number or less.

  A conventional powder material for additive manufacturing is adjusted in particle size by general pulverization and classification. According to the study by the present inventors, very fine particles are unavoidably present in these powders. The proportion of the fine particles is very small (for example, about 3% or less) based on, for example, volume and weight. However, it has been found that the presence of the powder regardless of the average particle diameter of the powder can greatly affect the powder flowability. Therefore, in the technique disclosed herein, the ratio of fine particles having a particle diameter of 20 μm or less that can affect the fluidity is limited to a small amount of 15% or less on the number basis. Thereby, even if it is a case where it uses, for example for a drop supply type powder layered modeling apparatus, generation | occurrence | production of the clogging of the modeling material at the time of powder supply, etc. can be suppressed. As a result, the homogeneity and surface flatness of one layer of the powder material formed on the modeling table can be improved. By this, the modeling material provided with suitable fluidity | liquidity suitable for powder layered modeling is provided.

  In a preferred embodiment of the technology disclosed herein, the powder has a volume-based average particle diameter of 20 μm or more and 130 μm or less based on a laser diffraction / scattering method. Thereby, in the modeling apparatus currently used widely, the modeling material which enables modeling with high modeling precision is provided.

  In a preferred embodiment of the technology disclosed herein, the powder has a cumulative mass of particles having a particle diameter exceeding 45 μm of 45% by mass or less. A metal material or a ceramic material is less likely to be melted when energy such as an electron beam or a laser beam is supplied compared to a resin material. Therefore, by limiting the ratio of coarse particles as described above, a modeling material that is easily melted and capable of modeling a dense model is provided. As a result, for example, a modeling material capable of modeling in a short time by increasing the laser scanning speed is provided.

  In a preferred embodiment of the technology disclosed herein, the powder is any one method selected from the group consisting of a pulverization method, a plasma atomization method, a gas atomization method, a water atomization method, a powder spray method, and a granulation method. It is manufactured. The powder produced by these methods is produced as a collection of non-spherical particles with a wide particle diameter, unlike resin particles that can be more precisely adjusted in particle shape and size based on the production method. Is done. Therefore, it is preferable to apply the present invention to such a powder because the effects of the present invention are suitably exhibited.

  In a preferred embodiment of the technology disclosed herein, the powder contains at least a metal powder in a proportion of 50% by mass or more. The metal powder has a relatively high specific gravity as compared with a resin material, a ceramic material, and the like, and tends to be clogged in a drop supply type powder additive manufacturing apparatus. Therefore, it is preferable to apply the present invention to such a powder because the effects of the present invention are suitably exhibited.

  In a preferred embodiment of the technology disclosed herein, the powder includes at least a ceramic powder in a proportion of 50% by mass or more. Ceramic powders tend to absorb moisture in the environmental atmosphere relatively easily compared to resin materials and metal materials. Therefore, depending on the storage environment or modeling environment of the modeling material, there is a concern that the modeling material absorbs moisture and easily becomes clogged. Therefore, it is preferable to apply the present invention to such a powder because the effects of the present invention are suitably exhibited.

  In a preferred embodiment of the technology disclosed herein, the powder includes a resin material at least partially. For example, the modeling material may be configured to include a binder material in advance depending on the modeling method of the powder additive manufacturing apparatus to be used. Moreover, the resin material may be included as a material which comprises the target molded article. These resin materials are made by attaching finer particles in powder to coarser particles and distorting the particle shape, and because they are soft, they fit with particles made of metal material or ceramic material, etc. The fluidity of the powder can be reduced. Therefore, it is preferable to apply the present invention also to such a powder because the decrease in fluidity can be suppressed.

  The fluidity of the above modeling materials is improved by particle size control different from the conventional materials. Therefore, it is possible to supply a material that is more uniform and more uniform than usual under general supply conditions. As a result, it becomes possible to improve the modeling accuracy in powder additive manufacturing. Alternatively, it may be possible to perform modeling at a higher speed while maintaining modeling accuracy under severer conditions. From such a viewpoint, the technique disclosed herein also provides a method for manufacturing a three-dimensional structure using the above modeling material. Furthermore, in another aspect, the technology disclosed herein also provides a manufacturing method of a modeling material for manufacturing the modeling material.

FIG. 1 is a diagram illustrating an electron microscope image of a conventional modeling material. FIG. 2 is a diagram illustrating an electron microscope image of a modeling material according to an embodiment. FIG. 3 is a cross-sectional view illustrating the configuration of a drop-feed type additive manufacturing apparatus.

  Hereinafter, preferred embodiments of the present invention will be described. Note that matters other than matters specifically mentioned in the present specification and necessary for the implementation of the present invention include the teachings on the implementation of the invention described in the present specification and the common general technical knowledge at the time of filing in this field. Can be understood and implemented by those skilled in the art based on the above. Further, the drawings are not necessarily limited to those reflecting actual dimensional relationships (length, width, thickness, etc.). In this specification, “X to Y” indicating a range means “X or more and Y or less”.

(Material for modeling)
The “modeling material” disclosed herein is a powdery material for use in powder layered modeling. Powder additive manufacturing broadly encompasses various types of modeling techniques using powdered materials as materials for modeling objects in the additive manufacturing technology. Specifically, for example, a directed energy deposition represented by a binder jetting method represented by a binder jet method, a laser beam welding, an electron beam welding, an arc welding, and the like. And a so-called powder bed fusion method represented by a laser sintering method, a selective laser sintering (SLS) method, an electron beam sintering method, and the like. From the viewpoint that this modeling material is suitable for modeling a dense model, it is more preferable to employ a directional energy deposition method and a powder bed fusion bonding method.

  As a result of intensive studies on the fluidity of conventional powder molding materials, the present inventors have found the following matters. That is, the conventional modeling material typically has a purpose of ensuring modeling quality, and is pulverized by a pulverizer or the like according to required modeling accuracy (for example, modeling thickness for each layer), a vibration sieve machine, etc. Grain size adjustment by sieving by, etc. was generally performed. For example, the particle size of the metal powder for additive manufacturing is generally adjusted to about −45 + 15 μm (that is, smaller than 45 μm and larger than 15 μm). As a result, the particle size distribution (frequency distribution) of the material for modeling subjected to such particle size adjustment, for example, ideally has a shape close to a normal distribution near the center, and has a large particle size side and a small particle size side. And the particles may be cut (removed) to show a shape with reduced frequency. For the management of the particle size distribution of industrially produced modeling materials, generally, a volume-based particle size distribution is adopted based on a laser diffraction / scattering method. However, as a result of detailed observations by the present inventors, the conventional modeling material was observed with an electron microscope, for example, whether or not the particle size was adjusted. In some cases, it was confirmed that a large number of fine particles were present. The inventors have studied various methods for adjusting the particle size, and as a result of selectively removing such fine particles, the present inventors have found that the fluidity of the modeling material is dramatically improved, thereby completing the present invention. It came to.

  The modeling material disclosed here includes at least one powder selected from the group consisting of metal materials and inorganic materials. The cumulative mass of particles having a particle diameter exceeding 45 μm in this powder is 0.5% by mass or more of the whole, and the number of particles having a particle diameter of 20 μm or less based on observation with an electron microscope is 15% by number or less. .

(Metal material)
The metallic material essentially comprises a metal. The powder containing a metal material typically contains a metal as a main component. A main component here means the component which occupies 70 mass% or more of the said metal material containing powder. The metal material-containing powder is preferably 80% by mass or more, more preferably 90% by mass or more, particularly preferably 95% by mass or more (typically 98% by mass or more).

  It does not restrict | limit especially as a metal, For example, the alloy etc. which consist of the simple substance of various metal elements, these elements, and 1 or more types of other elements may be sufficient. As a simple metal, for example, typically, magnesium (Mg), aluminum (Al), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel ( Ni), copper (Cu), zinc (Zn), zirconium (Zr), gold (Au), silver (Ag), platinum (Pt), iridium (Ir), bismuth (Bi), niobium (Ni), molybdenum ( Examples include Mo), tin (Sn), tungsten (W), and lead (Pb). Of course, inclusion of elements other than those exemplified here is allowed as a matter of course.

Moreover, as an alloy, specifically, as an example, a Cu-Al alloy, a Cu-Al-Fe alloy, a Cu-Ni alloy, a Cu-Ni-In alloy, a copper alloy, a Ni-Al alloy, Ni-Cr alloy (for example, Ni-20Cr alloy, Ni-50Cr alloy, Inconel 600, Inconel 625, Inconel 718, Inconel X750 etc. Inconel), Ni-Cr-Fe alloy (for example, Incoloy), Ni-Cr-Al alloy , Hastelloy (e.g., Ni-Fe-Mo alloy, Ni-Cr-Mo alloy), nickel alloy represented by Ni-Cu alloy (e.g., Monel), cobalt as a main component, Co-Cr-W alloy ( For example, stellite), Co-Cr-Ni-WC alloy, Co-Mo-Cr-Si alloy, Co-Cr-Al-Y alloy, etc. Alloys, Ni-Cr-Fe-Si-BC alloys, Ni-Cr-Mo-Cu-Fe-Si-BC alloys, and other Ni self-fluxing alloys, Co-Ni-Cr-Mo-Fe -Co self-fluxing alloy represented by Si-B-C, Al-Cu alloy, Al-Si-Mg alloy, aluminum alloy represented by Al-Mg alloy, Fe-36Ni alloy, Fe-Ni-Co alloy Invar alloy typified by, etc., Kovar alloy typified by Fe-29Ni-17Co alloy, etc., low carbon steel typified by maraging steel, carbon steel, SUS304, SUS316, SUS316L, SUS410, SUS420J2, SUS431, SUS630, etc. Stainless steel represented by Ti, titanium alloy represented by Ti-6Al-4V, and the like. In addition, an alloy here is the meaning which includes the substance which consists of said metal element and one or more other elements, and shows a metallic property, Comprising: The mixing method is a solid solution, an intermetallic compound. And a mixture thereof. Furthermore, other elements may be added to the composition system exemplified above.
Any one of the above metals and alloys may be included alone, or two or more of them may be included in combination.

(Inorganic material)
Inorganic materials essentially comprise inorganic materials. The powder containing an inorganic material typically contains an inorganic material as a main component. A main component here means the component which occupies 60 mass% or more of the said inorganic material containing powder. The inorganic material-containing powder is preferably 70% by mass or more, more preferably 75% by mass or more, and particularly preferably 80% by mass or more (typically 90% by mass or more) made of an inorganic material. Inorganic materials typically include ceramic.

The ceramic may be, for example, a ceramic (oxide ceramic) material made of various metal oxides, or a ceramic made of non-oxide such as carbide, boride, nitride, apatite (phosphate), etc. It may be a material.
Here, the oxide-based ceramic is not particularly limited, and may be various metal oxides. Examples of the metal element constituting such an oxide-based ceramic include metalloid elements such as boron (B), silicon (Si), germanium (Ge), antimony (Sb), and bismuth (Bi), magnesium (Mg), Typical elements such as calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), aluminum (Al), gallium (Ga), indium (In), tin (Sn), lead (Pb), scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), silver (Ag), gold ( selected from a transition metal element such as u), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Er), lutetium (Lu) 1 type or 2 types or more are mentioned. Especially, it is preferable that it is 1 type, or 2 or more types of elements selected from Mg, Y, Ti, Zr, Cr, Mn, Fe, Zn, Al, and Er.

  More specifically, as an oxide-based ceramic, for example, alumina, zirconia, yttria, chromia, titania, cobaltite, magnesia, silica, calcia, ceria, ferrite, spinel, zircon, nickel oxide, silver oxide, copper oxide, oxidation Zinc, gallium oxide, strontium oxide, scandium oxide, samarium oxide, bismuth oxide, lanthanum oxide, lutetium oxide, hafnium oxide, vanadium oxide, niobium oxide, tungsten oxide, manganese oxide, tantalum oxide, terpium oxide, europium oxide, neodymium oxide , Tin oxide, antimony oxide, antimony-containing tin oxide, indium oxide, tin-containing indium oxide, zirconium oxide aluminate, zirconium oxide silicate, hafnium oxide aluminate, oxide huff Um silicate, titanium silicate, lanthanum oxide silicate, lanthanum oxide aluminate, yttrium oxide silicate, titanium oxide silicates include tantalum oxide silicates and the like.

Examples of non-oxide ceramics include tungsten carbide (WC), chromium carbide (CrC), vanadium carbide (VC), niobium carbide (NbC), molybdenum carbide (Mo ₂ C), tantalum carbide (TaC), Carbides such as titanium carbide (TiC), zirconium carbide (ZrC), hafnium carbide (HfC), silicon carbide (SiC), boron carbide (BC), titanium boride (TiB ₂ ), zirconium boride (ZrB ₂ ), boron Borides such as tantalum boride (TaB ₂ ), hafnium boride (HfB ₂ ), chromium boride (CrB ₂ , CrB), tungsten boride (WB), molybdenum boride (MoB), boron nitride (BN), nitriding Nitride such as titanium (TiN), silicon nitride (SiN), aluminum nitride (AlN), forsterite Composites such as steatite, cordierite, mullite, barium titanate, lead titanate, lead zirconate titanate, Mn-Zn ferrite, Ni-Zn ferrite, sialon, phosphate compounds such as hydroxyapatite, calcium phosphate, etc. Can be mentioned.

  The above ceramics may contain elements other than those described above. In addition, these ceramics may be either one kind of simple substance, or two or more kinds may be combined. For example, when two or more kinds of ceramics are included, part or all of them may form a composite. Examples of such composite ceramics include, for example, yttria stabilized zirconia, partially stabilized zirconia, gadolinium doped ceria, lanthanum doped lead zirconate titanate, the above sialon, and the above composite oxide. Thing etc. are mentioned.

(cermet)
In addition, said metal material and inorganic material may comprise the cermet. For example, the cermet can be prepared by using the above ceramic powder as a hard phase and using the above metal powder as a binder (metal phase) and mixing and sintering them. The material constituting the cermet is not particularly limited. Examples of the ceramic component include oxide ceramics such as alumina, carbide ceramics such as tungsten carbide and titanium carbide, and nitride ceramics such as titanium nitride and titanium carbonitride. Hard materials such as boride ceramics represented by titanium boride, zirconium boride, tantalum boride, hafnium boride, chromium boride, tungsten boride, molybdenum boride and the like can be preferably used. Moreover, as a metal component, nickel, cobalt, molybdenum etc. can be used preferably, for example. In mixing and sintering these materials, a powder containing cermet can be suitably prepared by using a known spray drying method or the like.

  Here, the ratio of the hard phase and the metal phase in the cermet is not particularly limited. For example, the ratio of the metal phase to the entire cermet (the total of the hard phase and the metal phase) can be 10 mass% or more, for example, 15 mass% or more and 85 mass% or less. This makes it possible to obtain a modeling material capable of being precisely modeled by suitably spreading the metal phase on the surface of the hard phase that is not easily melted. The proportion of the metal phase can be appropriately adjusted according to the physical properties of the desired shaped article, but is preferably 20% by mass or more, more preferably 25% by mass or more, and particularly preferably 30% by mass or more. However, too much metal phase is not preferable because the characteristics of the hard phase containing ceramic may be impaired. Therefore, the ratio of the metal phase is specified to be less than 85% by mass. The proportion of the metal phase can be appropriately adjusted according to the physical properties of the desired shaped article, but is preferably 80% by mass or less, more preferably 75% by mass or less, and particularly preferably 70% by mass or less.

(Resin material)
Moreover, the modeling material disclosed here can contain a resin material in addition to the metal material and the inorganic material. Various materials can be considered as the resin material. For example, a modeling component included for the purpose of modeling and a binder component included for the purpose of the binder function can be considered.

(Modeling ingredients)
The resin material used as the modeling component has a role as a functional material for imparting desired characteristics to the modeled object in a modeled object obtained by modeling, and can also serve as a binder for binding powder. Such a resin material is not particularly limited, and various resin materials can be appropriately selected and used according to desired characteristics and the like. For example, specifically, a thermoplastic resin or a thermosetting resin that can be suitably formed by heating can be used.

  As a thermoplastic resin, the synthetic resin which can obtain the thermoplasticity of the grade which can be shape | molded by heating can be included widely without a restriction | limiting. In the present specification, the term “thermoplastic” means a property that reversibly softens when heated and can be plastically deformed, and reversibly cures when cooled. In general, a resin having a chemical structure composed of a linear or branched polymer can be considered. Specifically, for example, polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polystyrene (PS), thermoplastic polyester, acrylonitrile butadiene styrene (ABS), acrylonitrile styrene (AS), poly General purpose resins such as methyl methacrylate (PMMA), polyvinyl alcohol (PVA), polyvinylidene chloride (PVDC), polyethylene terephthalate (PET), vinyl acetate, polyamide (PA), polyacetal (POM), polycarbonate (PC), polyphenylene ether (PPE), modified polyphenylene ether (m-PPE; also referred to as m-PPO), polybutylene terephthalate (PBT), ultrahigh molecular weight polyethylene (UHPE), polyvinylidene fluoride (PVdF), etc. Zineering plastic, polysulfone (PSF), polyethersulfone (PES), polyphenylene sulfide (PPS), polyarylate (PAR), polyamideimide (PAI), polyetherimide (PEI), polyetheretherketone (PEEK) And super engineering plastics such as polyimide (PI), liquid crystal polymer (LCP), and polytetrafluoroethylene (PTFE). Any one of these may be used alone, or two or more may be used in combination.

  As the thermosetting resin, a synthetic resin that undergoes polymerization to form a polymer network structure upon heating and cannot be restored by curing can be widely included without limitation. In the present specification, “thermosetting” is a property in which a reaction proceeds in a polymer by heating and crosslinking occurs to form a network structure and cure. Specifically, for example, phenol resin (PF), epoxy resin (EP), melamine resin (MF), urea resin (urea resin, UF), unsaturated polyester resin (UP), alkyd resin, polyurethane (PUR), Examples thereof include thermosetting polyimide (PI). The thermosetting resin may be, for example, a mixture of low molecular weight monomers or a polymer that has been polymerized to some extent. Any one of these may be used alone, or two or more of them may be used in combination (including a blend).

(Binder component)
As the binder component, it is possible to use various resin materials that become viscous when softened or melted and exhibit binding properties (binder performance) when cured again. Such a resin material is not particularly limited, and examples thereof include polyvinyl alcohol, carboxymethyl cellulose, polyvinyl pyrrolidone, acrylic resin, urethane resin, and polyimide resin.

  These resin materials may be included so as to coat the surface of the powder made of the above metal material and / or inorganic material, and powdery resin particles are mixed or integrated in the above powder. May be.

(Rough particle ratio)
In the powder, the cumulative mass (mass ratio) of particles having a particle diameter exceeding 45 μm is 0.5% by mass or more of the whole. Thereby, it can be grasped that the powder as a whole contains a certain amount of large particles suitable for powder additive manufacturing. The ratio of the particles having a particle diameter exceeding 45 μm is preferably 1% by mass or more, more preferably 5% by mass or more, and particularly preferably 10% by mass or more. From the viewpoint of improving modeling accuracy, the ratio of particles exceeding 45 μm is preferably 45% by mass or less, for example.

  The proportion of particles exceeding 45 μm can be preferably grasped by a screening test using a sieve having an opening of 45 μm. The sieving test can be carried out according to, for example, dry sieving specified in JIS Z8815: 1994.

(Average particle size)
The average particle diameter of the powder is not particularly limited, and can be, for example, a size suitable for the standard of the powder additive manufacturing apparatus to be used. For example, it may be a size suitable for supplying one layer of modeling material in powder additive manufacturing. When the upper limit of the average particle diameter of the powder is larger, it can be, for example, more than 130 μm, typically 130 μm or less, preferably 100 μm or less, more preferably 75 μm. Hereinafter, it is more preferably 50 μm or less, particularly preferably 45 μm or less, for example, 40 μm or less. As the average particle diameter of this powder decreases, for example, the filling rate in the modeling tank of the powder additive manufacturing apparatus can be improved. As a result, the density of the three-dimensional structure to be modeled can be suitably increased. In addition, the surface roughness (Ra) of the three-dimensional structure to be formed can be reduced, and the effect of improving the dimensional accuracy can be obtained.

  The lower limit of the average particle diameter of the powder is not particularly limited as long as it does not affect the fluidity of the modeling material. Although not necessarily limited thereto, the average particle diameter is preferably, for example, 23 μm or more, more preferably 25 μm or more, for example, 30 μm or more, from the viewpoint of limiting the number of particles of 20 μm or less described later. can do. By making the average particle diameter relatively large, for example, handling when forming a modeled object and fluidity of the modeling material can be improved as a whole. As a result, it is preferable because the modeling material can be satisfactorily supplied to the modeling apparatus, and the finished three-dimensional modeled object can be finished well. In addition, the fluidity | liquidity here is mainly intending transportability and workability (laying property). When the powder has such an average particle size, the above requirements can be easily satisfied with respect to the proportion of particles having a particle size exceeding 45 μm.

  The “average particle size” of the above powder is the particle size at 50% cumulative (50% volume average particle size) in the volume-based particle size distribution measured by a particle size distribution measuring apparatus based on the laser diffraction / scattering method, unless otherwise specified. Diameter; Dv 50%).

(Number ratio of fine particles)
In the powder disclosed here, the number of particles having a particle diameter of 20 μm or less based on observation with an electron microscope is regulated to 15% by number or less. According to the study by the present inventors, in various powders that are subjected to general particle size adjustment and satisfy the requirement that the ratio of particles having a particle diameter of more than 45 μm is 0.5 mass% or more, the particle diameter is It is considered that when particles of about 20 μm or less come into contact with coarser particles, the movement of the coarse particles is likely to be inhibited when the coarse particles try to flow, for example, by being sandwiched between the coarse particles. Therefore, by restricting the number of fine particles having a size of 20 μm or less that can greatly affect the decrease in fluidity to 15% by number or less, the fluidity of the powder can be reliably and dramatically increased. The number of fine particles of 20 μm or less is preferably 12% or less, more preferably 10% or less, further preferably 8% or less, particularly preferably 5% or less, and for example, 3% or less. it can.

  The particles having a particle size of 20 μm or less are particles that are difficult to classify by adhering to the surface of coarser particles in the above screening test. Further, when such fine particles are evaluated on a volume basis and a mass basis as in the above-described laser diffraction / scattering method or screening test, the frequency (volume, mass, etc.) can be ignored because the dimensions are minute. It is measured as small as possible. Therefore, in the technique disclosed herein, the number of fine particles having a particle diameter of 20 μm or less is grasped based on the number of observations based on observation with an electron microscope.

  For reference, in various powders that have been subjected to general particle size adjustment and satisfy the requirement that the ratio of particles having a particle diameter exceeding 45 μm is 0.5 mass% or more, fine particles of 20 μm or less are For example, it may be about 5% by volume or less, or 5% by mass or less. On the other hand, when fine particles of 20 μm or less are evaluated on the basis of the number, the ratio can be as high as about 20 to 50 number%. In this respect, the modeling material disclosed herein is clearly distinguished from conventional powders that have been subjected to general particle size adjustment.

  The “particle diameter” for particles having a particle diameter of 20 μm or less is a particle diameter measured based on observation with a general electron microscope. In this specification, an equivalent circle diameter measured based on an observation image with a magnification of 200 times is employed. Although it does not restrict | limit especially as an electron microscope, The scanning electron microscope (SEM), transmission electron microscope (TEM), microscope, etc. which are widely used for this kind of analysis can be used. In calculating the equivalent circle diameter, for example, appropriate image analysis software may be used.

  Further, it is difficult to strictly measure all the number of particles having a particle diameter of 20 μm or less based on observation with an electron microscope, which can be an excessive burden. Furthermore, it is not preferable that the lower limit of the particle size that can be counted depends on the electron microscope used, the resolution of the observation image, and the like. And even if it is a particle | grain with a particle diameter of 20 micrometers or less, about the sufficiently small particle | grain, it is thought that the effect | action which inhibits the flow of a coarse particle is small. Therefore, for example, when the number of particles having a particle size of 20 μm or less is measured using an observation image having a magnification of 200 times as described above, for example, among particles constituting a powder, particles having a particle size of 1 μm or more are measured. Can be targeted. Also, when counting the number of particles having a particle size of 20 μm or less, an observation image having a resolution that can confirm particles having a particle size of 1 μm or more can be used.

  The above modeling material can be typically prepared by appropriately adjusting the particle size of a powder containing a metal and / or ceramic as a raw material. Here, the production method of the powder as a raw material is not particularly limited, but the external shape of the powder may be characteristic depending on the production method. In general, a metal or ceramic that has not been subjected to spheronization treatment tends to have a distorted shape due to its manufacturing method. For example, as an industrial production method of powder, typically, a pulverization method, a plasma atomization method, a gas atomization method, a water atomization method, a powder spray method, a granulation method, and the like can be given. Among these, although the plasma atomization method can obtain particles that are almost spherical, there is a disadvantage that the cost is relatively high. Each of the other powder manufacturing methods has an advantage of relatively low cost, but it is easy to obtain an irregularly shaped powder. In particular, when a ceramic powder that is a pulverized product is included, the tendency is increased because the powder is crushed along the crystal plane. In addition, when a metal powder produced by a gas atomization method, a water atomization method, or the like is included, jade-shaped particles are formed, or particles having a shape in which minute particles are firmly attached to the surface of coarse particles are formed. . As a result, the fluidity of the powder is relatively reduced. However, according to the technique disclosed herein, the fluidity can be suitably increased even in a powder composed of non-spherical particles by adjusting the particle size as described above. From this point of view, the modeling material disclosed herein is not limited to the powder produced by the plasma atomization method, but also the powder produced by the pulverization method, gas atomization method, water atomization method, powder spray method and granulation method. Can also be preferably targeted.

(Method for manufacturing modeling material)
As described above, the modeling material in the present embodiment can be prepared, for example, by appropriately adjusting the particle size of a general powder material, a modeling material provided as a layered modeling powder, or the like. As a method for adjusting the particle size, for example, first, a raw material powder including a powder having a desired composition is prepared. At this time, the raw material powder may be preliminarily adjusted in particle size so that the cumulative mass of particles having a particle diameter exceeding 45 μm is approximately 0.5 mass% or more of the whole. When a raw material powder having a ratio of such particles of 0.5% by mass or more from the original is obtained, there is no need for preliminary adjustment. Next, classification is performed to remove fine particles having a particle diameter of 20 μm or less from the raw material powder. Thereby, as above-mentioned, it can classify so that the ratio of the particle | grains of 20 micrometers or less may be 15 number% or less.

  The method of classification (removal of fine particles) is not limited to the method, and for example, either a wet method or a dry method can be employed. Furthermore, as a specific classification method, for example, a classification method that uses the difference in the drop speed and position of the particles due to gravity, or a classification method that uses centrifugal force by turning a fluid containing powder Etc. can be preferably employed. For example, as an example, centrifugal force acts strongly on coarse particles, and on fine particles, the centrifugal force is suppressed, and both are classified by the critical particle diameter, and the above centrifugal force An inertia classification method combined with inertial force can be employed. In this classification step, as described above, various classification conditions can be controlled for the purpose of selectively removing fine particles of 20 μm or less. Thereby, the modeling material disclosed here can be obtained.

(Method for manufacturing a three-dimensional structure)
The modeling material obtained as described above can be applied to various powder layered modeling. Then, as a suitable example of the manufacturing method of the three-dimensional structure disclosed here, the case where the laser selective sintering method (SLS) is mainly employed will be described as an example, and powder layered modeling will be described.
The manufacturing method of the three-dimensional structure disclosed herein generally includes the following steps.
(1) Supply of modeling material to modeling tank of powder additive manufacturing apparatus (2) Formation of thin layer of modeling material (3) Bonding of modeling material (4) Repeat of steps (1) to (3) above

  FIG. 3 shows an example of a simplified diagram of an additive manufacturing apparatus for powder additive manufacturing. As a rough configuration, the additive manufacturing apparatus has, as a rough configuration, a forming tank 10 that is a space in which powder additive manufacturing is performed, a supply device 20 that stores the forming material 1 and supplies the forming material 1 to the forming tank, and a forming material. Solidifying means (energy supply means such as a laser oscillator) 30 for solidifying 1. The modeling tank 10 typically includes a lifting table 12 that can be moved up and down in a modeling space surrounded by an outer periphery. The upper end of the modeling tank 10 coincides with the modeling surface. The lifting table 12 can move downward by a predetermined thickness Δt1 with respect to the modeling surface, and a target modeled object is modeled on the lifting table 12. The supply device 20 has a long and substantially V-shaped powder container, and a slit-shaped powder supply port is provided at the lower end of the powder container. Further, a squeegee blade 22 that assists the supply of the modeling material to the modeling tank 10 is provided on the lower surface of the supply device 20 along the longitudinal direction. The supply device 20 is horizontally disposed on the frame portion at the upper end of the modeling tank 10 so as to straddle the modeling tank 10, and is movable so as to be able to reciprocate in one direction orthogonal to the longitudinal direction of the supply apparatus 20. (Not shown).

1. Supply of modeling material In such a layered modeling apparatus, the modeling material for a predetermined thickness Δt1 is supplied by supplying the modeling material 1 to the modeling tank 10 in a state where the elevation table 12 is lowered by a predetermined thickness Δt1 from the modeling surface. A layer 40 can be provided. Specifically, the supply device 20 drops the modeling material 1 from the supply port while moving horizontally above the modeling tank 10. As a result, the modeling material 1 is supplied onto the lifting table 12 in the modeling tank 10.

2. Formation of the modeling material layer In parallel with or after the supply of the modeling material 1, the squeegee blade 22 provided on the lower surface of the supply device 20 converts the modeling material 1 supplied onto the lifting table 12. Level evenly. Thereby, the modeling material layer 40 whose surface is leveled can be prepared.

3. Then, for example, a heat source, a solidified composition or the like (hereinafter referred to as energy or the like) is supplied by the solidifying means 30 to the formed first layer of modeling material 40. This energy or the like is supplied only to the solidified region corresponding to the slice data of the first layer. Thereby, the modeling material 1 can be melted and / or sintered in a desired cross-sectional shape to form the first powder solidified layer (40).

4). Repeated Laminate Modeling Thereafter, the elevating table 12 is lowered by a predetermined thickness Δt1 and the modeling material is supplied again and leveled by the squeegee blade 22 to form the second modeling material layer 40. Then, only the solidification region corresponding to the slice data of the second layer of the modeling material layer 40 is applied with energy or the like via the solidifying means 30 to solidify the modeling material. As a result, a second powder solidified layer is formed. At this time, the powder solidified layer of the second layer and the powder solidified layer of the first layer which is the lower layer are integrated to form the laminate 42 up to the second layer.

  Subsequently, the lifting table 12 is lowered by a predetermined thickness Δt1 to form a new modeling material layer 40. Subsequently, energy or the like is supplied to the required location via the solidifying means 30. By repeating these steps, the target three-dimensional structure can be manufactured as the laminate 42 in which the powder solidified layer is integrated.

  In addition, as a means for solidifying the modeling material, for example, a method of injecting a composition for solidifying the modeling material by inkjet, a method of applying heat by a laser to melt and solidify the modeling material, or If the modeling material has a photocuring property, ultraviolet irradiation or the like is selected in accordance with the photocuring property. More preferably, it is a method of melting and solidifying the modeling material. For example, specifically, when the means for solidifying the modeling material is a laser, for example, a carbon dioxide laser or a YAG laser may be used publicly. it can. In the case where the means for solidifying the modeling material is injection of a composition by ink jetting, a composition containing polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl butyral, polyacrylic acid, polyacrylic acid derivative, polyamide or the like as a curing agent Alternatively, for example, a composition containing a polymerization initiator or the like, water, a mixture thereof, or the like can be used. Further, when a material having photocuring properties is used as a modeling material, an excimer laser (308 nm), a He—Cd laser (325 nm), an Ar laser (351 to 346 nm) having a wavelength region of ultraviolet light, visible light curing. When using a resin, an Ar laser (488 nm) or the like can be used. That is, it is preferable to select an appropriate means for solidifying the modeling material according to the characteristics of the modeling material to be used.

  The SLS method is an operation in which a laser beam is scanned on a powder layer on which a modeling material is deposited based on slice data created from three-dimensional CAD or the like, and the powder layer is melted and solidified into a desired shape. This is a technique for modeling a three-dimensional structure by repeatedly laminating each slice data). Similarly, the EBM method forms a three-dimensional structure by selectively melting and solidifying and laminating the powder layer using an electron beam based on slice data created from three-dimensional CAD or the like. Technology. Both techniques include a step of supplying a modeling material, which is a raw material of the structure, to a predetermined modeling position. In particular, in the SLS method and the EBM method, it is necessary to repeat a planarization step in which a modeling material is uniformly and thinly deposited with a thickness corresponding to one cross-sectional thickness over the entire modeling area where a structure is modeled. In the flattening process of the modeling material, the fluidity of the modeling material is an important parameter and greatly affects the finish of the three-dimensional model to be produced. On the other hand, since the modeling material used for the powder additive manufacturing in the present invention has good fluidity, it is possible to produce a three-dimensional structure with a good finish.

[Example]
EXAMPLES Examples relating to the present invention will be described below, but the present invention is not intended to be limited to those shown in the following examples.

  Four types of modeling powder made of SUS316L, which are commercially available as additive manufacturing powders, were prepared. These modeling powders are all manufactured by the gas atomization method, and the particle size is adjusted for a predetermined metal 3D printer. Hereinafter, the obtained powder for modeling may be referred to as a raw material powder.

  Each of the four types of modeling powders prepared was classified while adjusting the classification process conditions, and a process of removing particles of 20 μm or less was performed to obtain processed modeling powders. The classification process used the airflow classifier (prototype) which isolate | separates a coarse powder and a fine powder using the gravity difference by supplying powder in a high-speed swirling airflow.

  The following tests and evaluations were performed for each of the powders (raw material powders) as obtained and the processed powders, and the results are shown in Table 1 below.

  First, the particle size of each powder was measured using a laser diffraction / scattering particle size measuring device (LA-300 manufactured by Horiba, Ltd.). The cumulative 50% particle size (Dv 50%) and the cumulative 3% particle size (Dv 3%) based on the volume standard thus obtained were examined. The cumulative 3% particle size here means the particle size of the particle located at the 3% by volume from the smaller particle size side in the volume-based particle size distribution.

  Next, after preparing 100 g of each powder and sieving using a stainless steel sieve having an opening of 45 μm, the ratio of particles having a particle diameter exceeding 45 μm is measured by measuring the mass of the powder remaining on the sieve (mass%). Was calculated. As the stainless steel sieve, a test sieve that complies with JIS Z8801-1: 2006 was used.

  Further, SEM observation is performed on each powder, and the number of particles having a particle size of 20 μm or less and 1 μm or more in an image with a magnification of 200 times and the number of particles having a particle size of more than 20 μm are counted, and the particles occupy the whole particles The ratio of the number of particles having a diameter of 20 μm or less was calculated. For reference, FIGS. 1 and 2 illustrate SEM images of a raw material powder (Comparative Example 3) having an average particle diameter (Dv of 50%) of 41.2 μm and a powder after classification (Example 3), respectively. did. In addition, for the measurement of the particle diameter, an observation image in a state where each particle constituting the powder is dispersed so as not to overlap is prepared, and one particle is measured using image analysis software (Image-Pro, manufactured by Media Cybernetics). The circle diameter (equivalent circle diameter) of the same area calculated from the area value was adopted.

  Furthermore, the workability and fluidity of each of the raw material powder and the treated powder were evaluated, and the results are also shown in Table 1 below.

  First, evaluation of workability was performed by observing the surface of the powder layer obtained by supplying each powder to a modeling table using a powder layered modeling apparatus. Specifically, as a three-dimensional powder stereolithography apparatus, a laser-sintered three-dimensional powder stereolithography apparatus (manufactured by Matsuura Machinery Co., Ltd., LUMEX Avance-25) is used. A predetermined amount of each powder was stored in the powder supply device. This powder supply apparatus moves in the horizontal direction above the modeling tank while sequentially dropping the powder stored from the supply port provided in the lower part, and traverses the upper part of the modeling tank. At the same time, the supply device is provided with squeegee blades in front and rear in the movement direction of the supply port, and the supply device moves to flatten the powder supplied to the modeling tank by the squeegee blade. Therefore, each powder was supplied onto the modeling table in the modeling tank, with the powder supply conditions set to the movement of the supply device and the squeegee speed of 1 m / min, and the powder supply thickness to 0.5 mm.

  Moreover, the surface of the powder layer obtained in this way was observed visually, and it was observed whether linear after-rubbing was formed in the squeezing direction. The results are shown in Table 1 as “◯” when the surface was not rubbed and “×” when the surface was rubbed.

  Moreover, in order to evaluate the fluidity | liquidity in a supply apparatus, the fluidity | liquidity of the powder was measured according to the "metal powder-fluidity measuring method" prescribed | regulated to JISZ2502: 2012. Specifically, a test funnel was fixed to the funnel support, and 50 g of powder was supplied to the funnel with the orifice closed. Thereafter, the orifice was released and it was checked whether all the powder flowed out of the orifice. As a result, the case where all the powder flowed out was evaluated as “flowing”, and the case where the powder did not flow out at all was evaluated as “not flowing”, and are shown in Table 1.

[Evaluation]
As shown in Table 1, in the raw material powder (untreated powder), fine particles having a particle size of 20 μm or less, although depending on the average particle size, at a high rate of about 20 to 45% by number of the whole. It was confirmed that it was included. These fine particles correspond to very small particles seen between coarse particles in the SEM observation image of FIG. These fine particles are only very small in volume ratio, but when counted as the number, it can be seen that there are more than expected. The raw material powder used here is a relatively low-cost powder produced by a gas atomization method. In this powder, it can be confirmed that relatively small particles are bonded and integrated on the surface of the coarse particles, but these small particles are solidified by being integrated with the coarse particles in a molten state.

  On the other hand, about the powder after a process, it can confirm that the particle | grains below 20 micrometers are removed with high precision with less than 10 number% by the classification process. The removal of the fine particles can also be confirmed from the fact that very small particles are hardly seen between coarse particles in the SEM observation image of FIG. By this classification treatment, it can be confirmed that the average particle diameter (Dv50%) of the treated powder is slightly increased (about 0.5 to 3 μm). In addition, it can be confirmed that the cumulative 3% particle diameter (Dv 3%) has a higher degree of increase in the equivalent particle diameter than Dv 50% (about 1.3 to 3.7 μm). It was confirmed that this tendency was common even when the average particle diameter was significantly different from 25.2 μm (Comparative Example 1) to 46.0 μm (Comparative Example 4).

  In addition, the ratio of the particles remaining on the sieve having an opening of 45 μm by sieving is higher in Example 4 in which the treatment of removing particles of 20 μm or less is performed as compared with Comparative Example 4 and Example 4. . However, for the powders of Comparative Examples 1 to 3 having a large proportion of particles of 20 μm or less, the powders of Examples 1 to 3 after the treatment resulted in fewer particles on the sieve. This is because when the proportion of particles of 20 μm or less is large in ordinary powder (Comparative Examples 1 to 3), fine particles applied during sieving adhere to relatively coarse particles (the above-mentioned integrated particles are Thus, it is considered that the frequency of passing through a sieve having an opening of 45 μm as a whole (aggregated particles of coarse particles and fine particles) has increased. On the other hand, by performing a treatment for removing particles of 20 μm or less, the treated powder (Examples 1 to 3) can have coarse particles in their original size, and have a sieve with an opening of 45 μm. It is assumed that the frequency of passing has increased.

  And about workability, although the streaks could be confirmed on the surface of the powder layer in all examples (Comparative Examples 1 to 4) when the raw material powder was used, all the examples when the processed powder was used ( In Examples 1 to 4), streaks could not be confirmed on the surface of the powder layer. From this, it has been confirmed that the accuracy of powder additive manufacturing is improved by classification that strictly removes particles of 20 μm or less.

  In addition, regarding the fluidity, when the raw material powder was used, the powder was not discharged from the funnel in all the examples (Comparative Examples 1 to 4), whereas when the treated powder was used, all the examples ( In Examples 1 to 4), it was confirmed that the powder smoothly passed through the orifice and flowed out of the funnel. From this, it was confirmed that clogging and catching when passing through the shape of a conical tip such as a funnel are suppressed by classification that strictly removes particles of 20 μm or less, and the fluidity of the powder is remarkably enhanced. .

  The above results are achieved by strictly removing particles of 20 μm or less, regardless of the average particle diameter of the raw material powder. This is considered to be due to the fact that particles having a size of 20 μm or less or in the vicinity of the fluidity of the powder act as a trigger for intertwining larger particles. Therefore, it is considered that the fluidity and workability of the modeling material can be suitably improved by suppressing the ratio of particles of 20 μm or less to 15% by number or less.

  As mentioned above, although this invention was demonstrated by suitable embodiment, it cannot be overemphasized that such description is not a limitation matter and various modification | change is possible. Although not specifically shown, when a metal powder other than SUS steel or a ceramic powder is used as a modeling material, or when a resin material is added to this, a modeling material is used in the same manner as described above. Those skilled in the art can fully understand that the effect of the present technology is exhibited by the configuration. It can also be understood that a modeling object can be modeled with high accuracy and / or high speed by powder lamination modeling using such modeling material. Those skilled in the art can understand that the essence and advantages of the technology disclosed herein can be realized including various aspects.

DESCRIPTION OF SYMBOLS 10 Modeling tank 12 Lifting table 20 Supply apparatus 22 Squeegee blade 30 Solidification means 40 Modeling material layer 42 Laminate

Claims (7)

A modeling material used for powder additive manufacturing,
Including at least one powder selected from the group consisting of metal materials and inorganic materials,
In the powder, the cumulative mass of particles having a particle diameter exceeding 45 μm is 0.5% by mass or more of the whole,
A modeling material in which the number of particles having a particle diameter of 20 μm or less based on observation with an electron microscope is 15% by number or less.   The modeling material according to claim 1, wherein the powder has a volume-based average particle diameter of 20 μm or more and 130 μm or less based on a laser diffraction / scattering method.   The material for modeling according to claim 1 or 2, wherein the powder has an accumulated mass of particles having a particle diameter exceeding 45 µm of 45% by mass or less.   The powder is manufactured by any one method selected from the group consisting of a pulverization method, a plasma atomization method, a gas atomization method, a water atomization method, a powder spray method, and a granulation method. The modeling material according to any one of the above items.   The modeling material according to any one of claims 1 to 4, wherein the powder includes at least a metal powder in a proportion of 50% by mass or more.   The modeling material according to any one of claims 1 to 4, wherein the powder includes at least a ceramic powder in a proportion of 50% by mass or more. The modeling material according to claim 1, wherein the powder includes a resin material at least in part.