JP2020110824A - Mold making method and three-dimensional molding apparatus - Google Patents

Abstract

To provide a mold making method based on a three-dimensional molding apparatus easy to de-powder and allowing for making a mold for molding a casting having high dimensional accuracy and a fine surface, and a three-dimensional molding apparatus.SOLUTION: A mold making method has a direction determining procedure. In the direction determining procedure, the direction of a mold M is determined such that a casting forming surface of the mold M comes to an upper-face side. An upper face of the mold M thus made necessarily serves as a casting forming surface.SELECTED DRAWING: Figure 1

Description

The present invention relates to a mold manufacturing method and a three-dimensional modeling device.

2. Description of the Related Art Conventionally, there is a so-called 3D printer as a three-dimensional modeling device that embodies a three-dimensional shape drawn by computer graphics (CG) or the like with a resin material, a powder material, or the like. There are various methods for producing a three-dimensional object using a 3D printer. For example, there is a material extrusion method for forming a resin material, and a binder injection method (binder jet method) for forming a powder material.

According to the binder injection method, for example, the cement composition for a binder injection type additional manufacturing apparatus described in Patent Document 1 below is used as a powder material, and a powder is obtained by spraying an aqueous binder at a desired position. A solid is made by solidifying the material. The three-dimensional object is used, for example, in a mold into which molten metal, plastic, or the like (hereinafter referred to as “melt”) is injected when casting a casting.

JP, 2017-178671, A

However, the three-dimensional object manufactured from the hydraulic powder material as described above has a procedure of removing the powder material attached to the three-dimensional object (hereinafter, the procedure of removing the powder material is referred to as “depowder”). ), if the powder material is used as a mold with the powder material attached, the dimensional accuracy of the casting is low and the casting surface becomes rough.

The present invention has been proposed in view of such circumstances. That is, it is an object of the present invention to provide a mold manufacturing method and a three-dimensional modeling apparatus capable of easily de-powdering and capable of manufacturing a mold for casting a casting having high dimensional accuracy and a beautiful casting surface.

The three-dimensional object manufactured by the three-dimensional modeling apparatus using the binder injection method has different easiness of depowder (ease of adhesion of powder material) depending on the surface. Therefore, when a mold is manufactured by this three-dimensional modeling apparatus, a surface on which de-powdering is relatively easy is a surface on which a melt is poured and a casting is formed (hereinafter, referred to as "casting forming surface"). As a result, it becomes easy to depowder the molding surface. If the depowder is appropriate, the casting surface will be smooth and appropriate for casting.

In order to achieve the above-mentioned object, a method for producing a mold according to the present invention comprises an ascending/descending procedure of moving a stage for producing a mold to a position relatively lower than a reference plane, and crossing the stage from one side. By a recoater that moves to the other side to move the powder material on one side from the reference surface to the stage to level the material, and a binder is sprayed from the printer head to the powder material on the stage. A molding method for manufacturing a mold used for casting of a casting by including a molding procedure for solidifying the powder material by, and repeating the elevating procedure, the material filling procedure, and the molding procedure, wherein: Among the molds, the mold is manufactured in such a direction that the surface on which the casting is formed is the upper surface side.

The mold manufacturing method according to the present invention is characterized in that the mold is manufactured in such a direction that a portion having the largest surface area in the mold is on the upper surface side.

The mold manufacturing method according to the present invention is characterized by combining the molds to manufacture a core having an outer surface formed on a surface on which the casting is formed.

The mold making method according to the present invention is characterized in that the mold is dried at a temperature of 40 to 150 degrees.

The three-dimensional modeling apparatus according to the present invention includes a stage that moves a predetermined amount to a position relatively low with respect to a reference plane, and a powder that is on one side by moving from one side to the other side across the stage. A recoater that moves the material from the reference surface to the stage to level it, and a printer head that solidifies the powder material by spraying a binder onto the powder material of the stage are provided. A three-dimensional modeling apparatus for producing a mold used for casting of a casting by repeating a raising/lowering procedure, a material filling procedure by the recoater, and a modeling procedure by the printer head, wherein a surface of the casting for molding the casting is And a direction determining means for determining the orientation of the mold on the upper surface side.

The mold manufacturing method according to the present invention is for manufacturing the mold in such a manner that the surface of the mold for molding the casting is the upper surface side. That is, the upper surface of the manufactured die becomes the casting molding surface. The ease of de-powdering in the mold is that the upper surface is superior to the lower surface, so if the upper surface of the mold is a casting molding surface, de-powdering of the molding surface is easy and the casting surface is smooth and appropriate. Become. Therefore, de-powdering is easy, and a mold for casting a casting having high dimensional accuracy and a beautiful casting surface can be produced.

For example, when a plurality of molds are combined to form a main mold, the casting molding surfaces of the respective molds face each other inside. That is, all the casting molding surfaces of the main mold (inside the main mold) are excellent in ease of depowdering. Therefore, it is easy to depowder, and it is possible to produce a main mold for casting a casting having high dimensional accuracy and a beautiful casting surface.

In the mold manufacturing method according to the present invention, the mold is manufactured so that the part having the largest surface area in the mold faces the upper surface side. For example, when casting a casting having a complicated shape, the casting molding surface of the mold is naturally the same shape as the casting and is complicated. Therefore, in order to properly cast a casting having a complicated shape, it is preferable that the casting molding surface be easily depowdered in order to make the casting molding surface appropriate. In general, since a complicated shape has a relatively large surface area, the mold is manufactured so that the casting molding surface having the largest surface area is the upper surface of the mold. Therefore, even if the molding surface is complicated, de-powdering is easy, and a mold for casting a casting having high dimensional accuracy and a beautiful casting surface can be produced.

The mold manufacturing method according to the present invention is to combine molds to manufacture a core having an outer surface formed on a surface for forming a casting. That is, the core is a casting molding surface all of the outer peripheral surface, this core is created, for example, each half, if the mold having a casting molding surface with excellent ease of depowder is combined, All external surfaces of the child are excellent in de-powdering. Therefore, de-powdering is easy, and a core for casting a casting having high dimensional accuracy and a beautiful casting surface can be produced.

The mold making method according to the present invention may be subjected to a procedure of drying at a temperature of 40 to 150 degrees. That is, the ease of depowdering is increased by drying the mold at a predetermined temperature. Therefore, a mold for casting a casting having high dimensional accuracy and a beautiful casting surface can be produced.

The three-dimensional modeling apparatus according to the present invention has a direction determining unit that determines the orientation of the mold, where the surface of the mold on which the casting is formed is the upper surface side. Therefore, de-powdering is easy, and a mold for casting a casting having high dimensional accuracy and a beautiful casting surface can be produced.

1A and 1B are schematic views of a three-dimensional modeling apparatus used in a mold manufacturing method according to a first embodiment of the present invention. FIG. 1A is a plan view and FIG. 1B is a sectional view taken along line AA in FIG. is there. FIG. 2 is an external perspective view of a mold manufactured by the mold manufacturing method according to the first embodiment of the present invention. FIG. 3 is an external perspective view of a mold manufactured by the mold manufacturing method according to the comparative example. FIG. 4 is an external perspective view of a mold manufactured by the mold manufacturing method according to the reference example.

Hereinafter, a mold manufacturing method according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of the configuration of a three-dimensional modeling apparatus (hereinafter, the three-dimensional modeling apparatus is referred to as a “3D printer”) used in a mold manufacturing method.

The 3D printer 1 embodies the mold M by a binder injection method based on the data of the mold M expressed in three dimensions. First, the outline of the configuration of the 3D printer 1 will be described.

As shown in FIG. 1, the 3D printer 1 includes a stage 3 that moves up and down with respect to a reference surface 2, a material placing portion 4 that is outside the stage 3 and is on the reference surface 2, and a material placing portion 4 that is placed on the reference surface 2. A material supply unit (not shown) that supplies the powder material 5 to the placing unit 4, a recoater 6 that moves the powder material 5 from the material placing unit 4 to the stage 3 and smoothes it, and a powder material on the stage 3. The printer head 7 has a printer head 7 for spraying a binder onto the printer 5, and a guide portion 8 for freely moving the printer head 7. In the following description, as shown in FIG. 1, the three axes orthogonal to each other are defined as the X axis, the Y axis, and the Z axis, are parallel to the stage 3, and the lateral width direction of the stage 3 is the X axis. 3, the depth direction of the stage 3 is defined as the Y axis, and the height direction in which the stage 3 moves up and down is defined as the Z axis. On the X-axis, one of the widths is on the right side and the other is on the left side. On the Y-axis, one side is the back side and the other side is the front side.

The stage 3 has a rectangular flat plate shape and is a place where the mold M is produced. An elevating mechanism 9 is attached to the lower surface of the stage 3, and the elevating mechanism 9 operates to move the Z axis up and down. The material placing unit 4 is arranged outside the stage 3 and behind the stage 3. The material supply unit is arranged outside the stage 3 and above the material placing unit 4. Note that the material supply unit may be arranged outside the stage 3 and behind the material placing unit 4. The recoater 6 has a rod shape elongated in the X-axis direction, and is arranged on the reference plane 2. The recoater 6 freely moves on the reference plane 2 in a state parallel to the stage 3 between the back side of the material placing unit 4 and the front side of the stage 3 on the Y axis. The guide portion 8 is long in the X-axis direction and parallel to the stage 3, and freely moves in the Y-axis between the back side and the front side of the stage 3. The printer head 7 is supported by the guide portion 8 and freely moves on the X-axis.

Next, a procedure for producing the template M by the binder injection method using the 3D printer 1 will be described. The 3D printer 1 is input with the data of the desired mold M expressed in three dimensions. The fabrication procedure includes a direction determination procedure, a material supply procedure, a material filling procedure, a molding procedure, a drying procedure, and a depowder procedure. Each procedure is provided in the 3D printer 1 as a direction determining unit, a material supplying unit, a material filling unit, a modeling unit, a drying unit, and a powdering unit. The drying procedure (drying means) and the depowder procedure (depowder means) may be realized by an apparatus (not shown) separate from the 3D printer 1. The drying procedure is not mandatory.

In the direction determining procedure, the orientation of the template M to be produced is determined. More specifically, the orientation of the mold M is determined so that the casting molding surface of the mold M is on the upper surface side. The selection of the casting molding surface is arbitrary, but the portion having the most complicated shape in the mold M is selected as the casting molding surface. For example, in addition to the portion having the largest surface area, the portion where the height difference, unevenness, curve, etc. are most prominent is selected as the casting molding surface. In other words, the surface of the mold M where the melt is not poured and does not contact the casting is the lower surface side or the side surface side.

In the initial state in FIG. 1, the stage 3 is arranged on the same plane as the reference plane 2. In the ascending/descending procedure, the elevating mechanism 9 operates to lower the Z-axis of the stage 3, and the stage 3 moves to a position relatively lower than the reference plane 2 by a predetermined amount.

In the material supply procedure, the powder material 5 is supplied from the material supply unit to the material placement unit 4. The powder material 5 is placed on the material placing portion 4. The ascending/descending procedure and the material supplying procedure may be performed in sequence or simultaneously.

In the material filling procedure, the recoater 6 moves from the inner side of the material placing section 4 to the front side across the stage 3 on the Y axis, so that the powder material 5 moves from the material placing section 4 to the stage 3. Transferred. The powder material 5 is leveled on the stage 3 by the recoater 6 moving on the stage 3 along the reference surface 2. In some cases, the powder material 5 is filled into the stage 3 and leveled by repeating the material supply procedure a plurality of times.

In the modeling procedure, while the guide portion 8 moves in the Y-axis direction and the printer head 7 moves in the X-axis direction, the binder is sprayed from the printer head 7 at a preset position and the binder is sprayed. The powder material 5 is solidified at the point. The operation of the guide unit 8 and the printer head 7 will be described in detail. For example, the guide unit 8 is first arranged at the most front side in the manufacturing position. At this position, the printer head 7 ejects the binder while moving from the right side to the left side along the guide portion 8. Next, the guide portion 8 moves a predetermined amount to the back side, and at this position, the printer head 7 moves the right side to the left side to eject the binder. This operation is repeated, and the guide portion 7 moves to the innermost side in the mold M.

According to the lifting procedure, the material supplying procedure, the material filling procedure, and the molding procedure of the first round, the first laminate having a height corresponding to the predetermined amount of the stage 3 in the desired mold M is molded. In this way, the elevating procedure, the material supplying procedure, the material filling procedure, and the molding procedure are repeated a plurality of times, so that the first to n-th laminates connected in the Z-axis direction become the desired mold M and become the stage. 3 made on. Here, the upper side of the first laminate is the casting molding surface, and the lower surface of the first laminate is the surface that does not come into contact with the melt or the casting.

In the drying procedure, the state of being buried in the powder material 5 or the mold M from which the powder material 5 has been appropriately removed is left for 3 hours or more to be dried. At that time, the mold M is dried in an atmosphere of 40 to 150 degrees. The drying procedure may be shortened at higher temperatures. For example, if it is 150 degrees, it may take about 5 minutes. If it exceeds 150 degrees, the structure may be destroyed and the mold M may become fragile. Further, in the drying procedure, it may be dried at room temperature (for example, room temperature of about 20 degrees) for 3 hours or more. It may also be executed by a device (not shown) other than the 3D printer 1. Even if the drying procedure is not performed, de-powdering is easy on the upper surface side of the mold M, and by performing the drying procedure, de-powdering is also easy on the lower surface side. Even when the core, which is the second embodiment of the present invention described below, is manufactured as an integral body, if the complicated surface is manufactured as the upper surface side and the drying procedure is performed, depowder can be easily produced with a relatively beautiful casting surface. Become a possible core.

In the depowder procedure, the powder material 5 attached to the mold M is removed by, for example, a brush or the air of an air compressor. In the depowder procedure, the drying procedure may be executed by a device (not shown) other than the 3D printer 1.

The shape of the mold M produced in the first embodiment is various. For example, there is a case where a master mold is composed of a single mold M, or a case where a plurality of molds M are combined to form a master mold. In the former case, the specific outer surface of the main mold (single mold M) becomes the casting molding surface, and in the latter case, the inside of the main mold (the inner side surrounded by the plurality of molds M) is the casting molding surface. Becomes In the latter case, for example, among the main molds divided into the upper and lower parts, the upper mold M and the lower mold M are separately produced, and then the respective molds M are combined. Each of the molds M is produced with the casting molding surface facing upward, and when the casting molds M are combined, the casting molding surface of the upper mold M faces downward and the casting molding surface of the lower mold M faces. Is directed upwards. The inside of the completed main mold is the casting molding surface, and the hollow portion inside the main mold is composed only of the casting molding surface.

In the mold making method according to the second embodiment of the present invention, the core M is made by combining the molds M made by the mold making method according to the first embodiment. The core is used, for example, as a mold for a hollow portion when a hollow casting is cast. That is, in the core produced by combining the molds M, all of the outer surfaces are casting molding surfaces.

Next, the powder material 5 used in the manufacturing method will be described.

The powder material 5 is a hydraulic composition such as cement, gypsum, or lime, and contains a polymer in a specific ratio with respect to 100 parts by mass of a binder containing calcium aluminate in a specific ratio. Specifically, the hydraulic composition has the following constitution.

[1] A hydraulic composition containing 2 to 12 parts by mass of a polymer based on 100 parts by mass of a binder containing 50 to 100% by mass of calcium aluminate.
[2] The hydraulic composition according to [1], wherein the calcium aluminate is amorphous calcium aluminate.
[3] The hydraulic composition according to the above [1] or [2], wherein the polymer is polyvinyl alcohol.
[4] The hydraulic composition according to the above [3], wherein the degree of saponification of the polyvinyl alcohol is 80 to 90 mol %.
[5] The hydraulic composition according to the above [3] or [4], wherein the polyvinyl alcohol has an average particle size of 150 μm or less.
[6] The binder contains 0 to 20% by mass of cement having a setting (initial start) within 30 minutes, which is measured in accordance with JIS R 5210, with the entire binder being 100% by mass, [1] ~ The hydraulic composition according to any one of [5].
[7] The hydraulic composition according to any one of the above [1] to [6], wherein the binder contains 0 to 5 mass% of gypsum in terms of anhydrous gypsum with 100 mass% of the entire binder.

Since the hydraulic composition described above has high strength development and high heat resistance, when used in the mold M, it is possible to produce a defect-free casting with less gas generation during casting.

The hydraulic composition contains 2 to 12 parts by mass of the polymer with respect to 100 parts by mass of the binder containing 50 to 100% by mass of calcium aluminate.

Hereinafter, the calcium aluminate, which is an essential component of the binder, and cement, which is an optional component, will be separately described in detail.

<Calcium aluminate>
The calcium _{aluminate, 3CaO · Al 2 O 3,} 2CaO · Al 2 O 3, 12CaO · 7Al 2 O 3, 5CaO · 3Al 2 O 3, CaO · Al 2 O 3, 3CaO · 5Al 2 O 3 or CaO, · _2Al 2 _{O 3} and calcium aluminate; contains calcium aluminate in calcium fluorosilicone aluminate halogen 3CaO _· 3Al was dissolved or substituted ₂ O 3 · CaF _2, and the like _{11CaO · 7Al 2 O 3 · CaF} 2 calcium halo _{aluminate; 8CaO · Na 2 O · 3Al} 2 O 3, and calcium sodium aluminate such as _{3CaO · 2Na 2 O · 5Al 2} O 3; calcium lithium aluminate; alumina cement; further Na thereto, K, Li , Ti, Fe, Mg, Cr, P, F, S, and the like, one or more kinds selected from minerals in which trace elements (including oxides) are solid-solved.
Amorphous calcium aluminate does not substantially have a crystal structure because it is manufactured by melting the raw material and then rapidly cooling it. Usually, the vitrification rate is 80% or more, and the higher the vitrification rate, the higher the vitrification rate. Since the early strength development is high, the vitrification rate is preferably 90% or more.
The CaO/Al ₂ O ₃ molar ratio of calcium aluminate is preferably 1.5 to 3.0, more preferably 1.7 to 2.4. When the molar ratio is 1.5 or more, the early development of strength of the hydraulic composition is high, and when it is 3.0 or less, the heat resistance of the hydraulic composition is high.
In addition, the content of calcium aluminate is preferably 50 to 100% by mass, with the total amount of the calcium aluminate and the binder containing optional components such as cement and gypsum as 100% by mass. When the value is 50 mass% or more, the hydraulic composition has high early strength development and high heat resistance. The value is preferably 60 to 100% by mass, more preferably 70 to 100% by mass, and further preferably 80 to 95% by mass.
Also, the Blaine specific surface area of the calcium aluminate, in order to suppress the generation of dust with obtaining sufficient early strength development, preferably 1000~6000cm ² / g, more preferably 1500~5000cm ² / g. The Blaine specific surface area of the calcium aluminate is more preferably 1000 to 2500 cm ² /g, and particularly preferably 1500 to 2500 cm ² /g, in order that the laying in the additive manufacturing apparatus is uniform and the strength of the mold does not decrease. It is 2000 cm ² /g.

<Cement>
Cement is an optional component of the binder, and if the setting (initial) measured according to JIS R 5210 is within 3 hours and 30 minutes, early strength development after 3 hours from the time of manufacturing the mold M is Since it is high, the condensation (starting) is more preferably within 1 hour.
The content of cement in the binder is preferably 50% by mass or less, more preferably 30% by mass or less, further preferably 20% by mass or less, based on 100% by mass of the entire binder in order to improve early strength development. It is particularly preferably 10% by mass or less.
The content of calcium silicate in the cement is preferably 25% by mass or more. When the content is 25 mass% or more, the strength development is high after one day of age, and when long-term strength development is required, the content is preferably 45 mass% or more.
The cement is selected from fast-setting cement, ultra-fast setting cement, normal Portland cement, early-strength Portland cement, moderate heat Portland cement, low heat Portland cement, white Portland cement, ecocement, blast furnace cement, fly ash cement, and cement clinker powder. One or more may be mentioned. Cement clinker powder is also included in the cement.
Among these, quick-setting cement, ultra-quick-setting cement, or water-stop cement, which has a high early strength development property and preferably has a setting (initial start) within 30 minutes, is preferable. Commercial products such as fast-setting cement are Super Jet Cement (SJC: Taiheiyo Cement Co., Ltd.), Jet Cement (Sumitomo Osaka Cement Co., Ltd.), Lion Sisui (registered trademark, Sumitomo Osaka Cement Co., Ltd.), or Denka Super Cement. (Manufactured by Denka).

<gypsum>
Gypsum is an optional component of the binder, and includes one or more selected from anhydrous gypsum, hemihydrate gypsum, and gypsum dihydrate. Among these, hemihydrate gypsum is preferable because it has higher early strength development.
The content of gypsum in the binder is 100% by mass of the entire binder, preferably 5% by mass or less in terms of anhydrous gypsum, in order to improve strength and prevent gas and graphite spheroidization defects during production of castings. , More preferably 3 mass% or less, and further preferably 1 mass% or less.

Further, the gypsum may be gypsum contained in cement, and ultra-rapid hardening cement (for example, super jet cement manufactured by Taiheiyo Cement Co., Ltd.) whose content of gypsum in the cement is 5% by mass or more in terms of anhydrous gypsum is calcium. By mixing with aluminate and used as a binder, early strength development is improved.

<Polymer>
The content ratio of the polymer in the hydraulic composition is preferably 2 to 12 parts by mass in terms of solid content with respect to 100 parts by mass of the binder in order to further increase the strength of the hydraulic composition. If the content ratio of the polymer is less than 2 parts by mass, the effect of improving the strength is low, and bleeding may occur and the dimensional accuracy may be poor. If it exceeds 12 parts by mass, the mold M may be shrunk and deformed depending on the shape. In some cases, cracks may occur and a mold having a complicated shape cannot be manufactured. The content ratio of the polymer is more preferably 3 to 12 parts by mass and further preferably 4 to 10 parts by mass with respect to 100 parts by mass of the binder.
The polymer is, for example, a polymer dispersion or a re-emulsified powder resin defined in JIS A 6203 in the form of a polymer, or a polyacrylic ester, an ethylene/vinyl acetate copolymer in the form of a polymer. , Styrene/butadiene copolymer, vinyl acetate/vinyl versatic acid ester copolymer, vinyl acetate/vinyl versatic acid/acrylic acid terpolymer, polyvinyl alcohol, maltodextrin, epoxy resin, and urethane resin One or more may be mentioned.
Among these, polyvinyl alcohol (partially saponified or completely saponified polyvinyl acetate) is preferable, and polyvinyl alcohol having a saponification degree of 85 to 90 mol% is more preferable, because early development of strength can be obtained. ..
Further, since the early strength development property is obtained, the average particle size (median diameter D50) of polyvinyl alcohol is preferably 10 to 150 μm, more preferably 30 to 90 μm, because high strength is obtained. Therefore, when polyvinyl alcohol is mixed and pulverized with one or a plurality of binder raw materials and the particle size is adjusted, finer particles can be homogeneously mixed, and early strength development can be enhanced.
The polymer may be used in the form of powder by mixing it with a binder or sand, or may be used by dissolving it in water described later.

<sand>
The sand is not particularly limited as long as it is refractory sand, and one or more kinds selected from silica sand, olivine sand, zircon sand, chromite sand, alumina sand, artificial sand and the like can be mentioned.
The amount of sand is preferably 100 to 600 parts by mass with respect to 100 parts by mass of the binder. When the value is within the range, fire resistance and strength development can be secured. The blending amount is more preferably 150 to 500 parts by mass, and further preferably 200 to 400 parts by mass with respect to 100 parts by mass of the binder.

<Curing accelerator>
The hydraulic composition may further contain a curing accelerator as an optional component in order to improve strength development. The curing accelerator is at least one selected from alkali metal carbonates, alkali metal lactates, alkaline earth metal lactates, and alkali metal silicates. These hardening accelerators have a high effect of improving strength development in a hydraulic composition in which the content ratio of the polymer is 2 to 6 parts by mass with respect to 100 parts by mass of the binder. In addition, these curing accelerators have a high effect of improving strength development when the curing temperature described later is as low as 10 to 40°C.
The (i) alkali metal carbonate includes one or more selected from sodium carbonate, potassium carbonate, and lithium carbonate. Further, (ii) the alkali metal lactate is
One or more selected from sodium lactate, potassium lactate, and lithium lactate can be used. (iii) Examples of the alkaline earth metal lactate include one or more selected from calcium lactate and magnesium lactate. Further, (vi) the alkali metal silicate may be one or more selected from sodium silicate, potassium silicate, and lithium silicate.
The content ratio of the curing accelerator is preferably 3 to 10 parts by mass with respect to 100 parts by mass of the binder. When the content ratio of the curing accelerator is within the range, it is possible to secure early strength development for rapid molding and handleable strength. The content ratio of the curing accelerator is more preferably 4 to 9 parts by mass, and further preferably 5 to 8 parts by mass with respect to 100 parts by mass of the binder. The curing accelerator can be used by mixing it with the hydraulic composition in advance, or by dissolving it in water supplied from the additional manufacturing apparatus.

<Other>
In order to facilitate the work (depowder) of removing the uncured powder of the hydraulic composition remaining after the molding from the mold M, the hydraulic composition is further added to 100 parts by mass of the total amount of the binder. As a component of 0.1 to 2 parts by mass, more preferably 0.5 to 1.5 parts by mass of hydrophobic fumed silica can be contained. Here, the hydrophobic fumed silica is silica powder in which the surface of fumed silica is treated with silane or siloxane to make the surface hydrophobic.
In addition, the BET specific surface area of the hydrophobic fumed silica is preferably 30 to 300 m ² /g in order to further improve the removal efficiency of the powder of the hydraulic composition. When the BET specific surface area of the hydrophobic fumed silica is within the range, the fluidity of the powder is improved, the surface spread by the additional manufacturing device is flat, and the weight of the mold M is reduced without lowering the strength. it can. Further, since the air permeability of the mold M is improved, defects are less likely to occur even if gas is generated during the production of the casting. Further, the hydrophobic fumed silica is effective in preventing the powder from consolidating and improving the mixing property.

In addition, the hydraulic composition may further contain an arbitrary component such as blast furnace slag, fly ash, silica fume, silica fine powder, and limestone powder as a strength developing agent.

<Method for producing template M>
In the mold making method, the mold M is made by using the additive manufacturing apparatus and the hydraulic composition used in the present invention. The additive manufacturing device is not particularly limited, and a commercially available product such as a powder lamination type additive manufacturing device can be used. Further, the hydraulic composition is prepared by mixing the above components with a commercially available mixer or manually. When a plurality of materials are used as the binder, the binder may be mixed in advance by a commercially available mixer or by hand, or may be mixed and ground by a grinder.
Further, water can be used as the binder. As the water, ordinary water supply, well water, or the like can be used. The hydraulic composition is preferably a composition containing 28 to 60 parts by mass of water and sand with respect to 100 parts by mass of the binder. When the blending ratio of water is within the range, strength development can be secured. The mixing ratio of water is preferably 30 to 55 parts by mass, more preferably 32 to 45 parts by mass, from the viewpoint of further increasing the strength and dimensional accuracy of the mold M. It should be noted that water may be used by mixing one or more selected from a thickener, a lubricant, a fluidizing agent, a surfactant, and a surface tension reducing agent in order to impart various necessary functions. Good.

The method of curing the mold M includes air curing alone, air curing followed by water curing, surface impregnating agent curing, and the like. Of these, air curing alone is preferable from the viewpoint of early strength development and suppression of steam generated during casting production. In addition, the temperature for curing in air is preferably 10 to 100° C., more preferably 30 to 80° C., from the viewpoint of strength enhancement by calcium aluminate, cement, and polymer. In addition, the relative humidity of air curing is preferably 10 to 90%, more preferably 15 to 80%, and further preferably 20 to 60% from the viewpoint of sufficient strength development and production efficiency. Further, the air curing time is preferably 1 hour to 1 week, more preferably 2 hours to 5 days, and further preferably 3 hours to 4 days from the viewpoint of sufficient strength development and production efficiency.

Next, an example of the mold manufacturing method will be described.

The 3D printer used in the examples is a binder jet method manufactured by ThreeD Systems Inc. (ProJet 660Pro), and the main specifications are as follows.
Stage: 254 x 381 x 203 (mm)
Stacking pitch: 100 (μm)
Laminating speed: About 28 (mm/h)

The molds M ₁ , M ₂ and M ₃ were prepared using the 3D printer described above. 2 to 4 show the respective templates M ₁ , M ₂ and M _{3 that} were produced. As shown in FIGS. 2 to 4, the molds M ₁ , M ₂ , and M ₃ are rectangular parallelepipeds and have an upper surface 10, a side surface 11, and a lower surface 12. Further, the sides A, B, and C are defined, and the design dimensions of the molds M ₁ , M ₂ , and M ₃ are as follows.
Side A = 10 (mm)
Side B=16 (mm)
Side C=80 (mm)

<Materials used>
The powder material used as the base of the mold M is composed of amorphous calcium aluminate:super jet cement:espearl:cera beads=0.9:0.1:1:1.
2% of the polymer was mixed with this mixture in an external ratio. The details are as follows.
(1) Amorphous calcium aluminate Amorphous calcium aluminate sample, CaO/Al ₂ O ₃ molar ratio is 2.2, vitrification rate is 95% or more, and Blaine specific surface area is 3490 cm ² /g. is there.
(2) Cement Super Jet Cement, manufactured by Taiheiyo Cement Co., Ltd., the content of calcium silicate is 47% by mass, the setting (starting) is 30 minutes, and the Blaine specific surface area is 4700 cm ² /g. However, it contains 14% by mass of anhydrous gypsum.
(3) Sand An equal amount of the following two types of artificial casting sand was mixed and used.
Sand 1 Alumina-based, trade name Spearl #180L, Yamakawa Sangyo Co., Ltd. Sand 2 alumina-based, trade name Naigai Cera Beads #1450 (registered trademark), ITOCHU Ceratech Co., Ltd. (4) Polymer polyvinyl alcohol Part number 22-88S1 (PVA217SS), Kuraray Co., Ltd. Saponification degree is 87 to 89%, average particle diameter (median diameter D50) is 60 μm, content of particles larger than 94 μm is 29% by mass, content of particles larger than 77 μm is 47% by mass, 10% diameter (D10) is 25 μm and 90% diameter (D90) is 121 μm.
(5) Water 3% by mass aqueous glycerol solution (binder solution for ProJet 660Pro), manufactured by 3D Systems. The water amount set value of the device is 65% outside and 90% inside, and the water/binder ratio is about 30%.

The mold M ₁ of the example is manufactured so that the casting molding surface is on the upper surface side. The mold M _{2 of the} comparative example is manufactured so that the casting molding surface is on the lower surface side. The mold M _{3 of the} reference example is the same as the mold M _2, and the lower surface is the casting molding surface. Three molds M ₁ , M ₂ and M ₃ were prepared for each of the examples, comparative examples and reference examples.

In the example, after the mold M ₁ was prepared, it was left in a room at about 20° C. for 3 hours to carry out depowder. In each of the first to third molds M ₁ , the lower surface 12 and the side surface 11 were completely depowdered. Next, a constant amount of air was blown onto each upper surface 10 (casting molding surface) for 30 seconds, and then the weight was measured (Example first measurement value). After that, the upper surface 10 (casting molding surface) was completely depowdered and the weight was measured (second measurement value of Example). The difference between the first measured value of the example and the second measured value of the example is the amount of the powder material adhered to the upper surface 10 (casting molding surface). The results are as follows.

First mold M ₁ : Example first measurement value-Example second measurement value=0.1 g
Second mold M ₁ : Example 1st measurement value-Example 2nd measurement value=0.1 g
Third mold M ₁ : Example first measurement value-Example second measurement value=0.1 g

That is, it can be seen from the examples that the casting molding surface is manufactured so that the casting molding surface is on the upper surface side, and the mold M ₁ is easy to depowder the casting molding surface. In other words, it can be seen that the mold depowder manufactured by the mold manufacturing method has the upper surface 10 easier than the lower surface 12.

In the comparative example, after the mold M ₂ was prepared, it was left in a room at about 20° C. for 3 hours to perform depowder. The upper surface 10 and the side surface 11 of each of the first to third molds M ₂ were completely powdered. Next, each lower surface 12 (casting molding surface) was blown with a constant amount of air for 30 seconds, and then the weight was measured (first measured value of Comparative Example). Then, the lower surface 12 (casting molding surface) was completely depowdered and the weight was measured (the second measured value of the comparative example). The difference between the first measured value of the comparative example and the second measured value of the comparative example is the amount of the powder material adhered to the lower surface 12 (casting molding surface). The results are as follows.

The first mold M _2: Comparative Example First measurement - Comparative Example The second measurement = 1.3 g
The second mold M _2: Comparative Example First measurement - Comparative Example The second measurement = 1.4 g
The third mold M _2: Comparative Example First measurement - Comparative Example The second measurement = 1.4 g

That is, it can be seen from Comparative Examples that it is difficult to depowder the casting molding surface of the mold M ₂ manufactured so that the casting molding surface is on the lower surface side. In other words, it can be seen that the lower surface 12 of the mold depowder manufactured by the mold manufacturing method is more difficult than the upper surface 10.

In the reference example, after being left in a room at about 20 degrees for 3 hours, drying was performed for 3 hours in an atmosphere at 40 degrees. The upper surface 10 and the side surface 11 of each of the first to third molds M ₃ were completely depowdered. Next, a constant amount of air was blown on each lower surface 12 (casting molding surface) for 30 seconds, and then the weight was measured (reference example first measurement value). Then, the lower surface 12 (casting molding surface) was completely depowdered and the weight was measured (reference example second measurement value). The difference between the first measured value of the reference example and the second measured value of the reference example is the amount of the powder material adhered to the lower surface 12 (casting molding surface). The results are as follows.

First mold M ₃ : Reference example first measurement value-reference example second measurement value=0.1 g
The second mold M _3: reference example first measurement value - reference example second measurement = 0.1 g
The third mold M _3: reference example first measurement value - reference example second measurement = 0.1 g

That is, even in the case of the mold M ₃ manufactured so that the casting molding surface is on the lower surface side, it is easy to depowder the casting molding surface by drying for 3 hours in an atmosphere of 40 degrees. I understand from. In other words, it can be seen that the mold manufactured by the mold manufacturing method is more easily de-powdered by drying at a predetermined temperature.

Next, the effects of the mold making method and the 3D printer 1 will be described.

As described above, the mold manufacturing method and the 3D printer 1 have a direction determining procedure (direction determining means), and in this direction determining procedure, the mold M of the mold M is positioned so that the casting molding surface of the mold M is on the upper surface side. The orientation is determined. With this configuration, the upper surface of the produced mold M inevitably becomes the casting molding surface. As can be seen from the examples and the like, the ease of de-powdering in the mold M is that the upper surface is superior to the lower surface, so if the upper surface of the mold M is a casting molding surface, de-powdering of the casting molding surface is easy. Yes, the molding surface is smooth and appropriate. Therefore, de-powdering is easy, and a mold M for casting a casting having high dimensional accuracy and a beautiful casting surface can be produced.

Further, in the direction determining procedure, the portion of the mold M having the most complicated shape is selected as the casting molding surface. Therefore, even if the molding surface is complicated, de-powdering is easy, and it is possible to manufacture the mold M for casting a casting having high dimensional accuracy and a beautiful casting surface.

In the mold making method and the 3D printer 1, as can be seen from the examples, the ease of depowder is increased by drying the mold M for 3 hours or more. Therefore, the mold M for casting a casting having high dimensional accuracy and a beautiful casting surface can be produced.

In the drying procedure, it is dried in an atmosphere of 40 to 150 degrees. That is, as can be seen from the reference example, the ease of depowder is increased by drying the mold M at a predetermined temperature. Therefore, the mold M for casting a casting having high dimensional accuracy and a beautiful casting surface can be produced. Even if the drying procedure of the present embodiment is not performed, the ease of de-powdering remains the same as the upper surface being superior to the lower surface.

In the mold manufacturing method according to the second embodiment, the cores are manufactured by combining the molds M manufactured by the mold manufacturing method according to the first embodiment. That is, in the core produced by combining the molds M, all the outer surfaces are casting molding surfaces, and all the outer surfaces of the core have excellent depowder easiness. Therefore, de-powdering is easy, and a core for casting a casting having high dimensional accuracy and a beautiful casting surface can be produced.

Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment. The present invention can be modified in various ways without departing from the matters described in the claims.

1 3D printer (three-dimensional modeling device)
2 Reference surface 3 Stage 4 Material placement part 5 Powder material 6 Recoater 7 Printer head 8 Guide part 9 Elevating mechanism 10 Upper surface 11 Side surface 12 Lower surface M, M _1-3 Mold (mold)

Claims (5)

The stage for producing the mold is moved up and down to a position relatively lower than the reference plane, and the recoater that moves from one side to the other side across the stage is used to remove the powder material on one side. A material filling step of moving the level material from the reference surface to the stage and leveling it, and a shaping step of solidifying the powder material by spraying a binder from the printer head onto the powder material of the stage, A mold manufacturing method for manufacturing a mold used for casting a casting by repeating the lifting procedure, the material filling procedure, and the molding procedure,
Of the molds, the surface for molding the casting is oriented so that it is the upper surface side, and the molds are manufactured.
A method for producing a mold, comprising: Among the molds, a part having the largest surface area is formed so that the mold is oriented in the direction of the upper surface side.
The method for producing a mold according to claim 1, wherein By combining the molds, a core having an outer surface formed on the surface forming the casting is produced.
The method for producing a mold according to claim 1 or 2, wherein: Undergoing a procedure of drying the mold at a temperature of 40 to 150 degrees;
The mold making method according to any one of claims 1 to 3, wherein: A stage that moves a predetermined amount to a relatively lower position with respect to the reference surface, and a powder material on one side from the reference surface to the stage by moving from one side to the other side across the stage. A moving and leveling recoater, and a printer head for solidifying the powder material by spraying a binder onto the powder material of the stage, and a lifting procedure by the stage, a material filling procedure by the recoater, A three-dimensional modeling apparatus for manufacturing a mold used for casting a casting by repeating a modeling procedure by the printer head,
Of the molds, the surface for molding the casting has a direction determining means for determining the orientation of the mold, which is the upper surface side,
A three-dimensional modeling device characterized in that

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