JP6037756B2 - Mold manufacturing method and mold - Google Patents

Description

  The present invention relates to a mold manufacturing method and a mold.

  As a casting method for producing a casting, there is a precision casting method used when producing a casting with high accuracy. As described in Patent Document 1, in the precision casting method, slurry is applied around a vanishing model (wax mold) having the same shape as the molded part, and then the first layer stucco (flower) is adhered and dried. Let Thereafter, the three steps of slurry application, stucco adhesion, and drying are repeated to produce a mold (outer mold) that covers the outside of the casting.

JP 2001-18033 A

  In the apparatus described in Patent Document 1, an outer mold having a desired thickness is formed by repeatedly performing three steps of slurry application, stucco attachment, and drying, thereby creating an outer mold having a desired strength. Here, the process of slurry application, stucco adhesion, and drying takes half to one day in one treatment. For this reason, the method of producing a template by repeating these three steps a plurality of times takes time to produce the template.

  This invention is made | formed in view of the above, Comprising: It aims at providing the casting_mold | template manufacturing method and casting_mold | template which can produce a casting_mold | template in a short time.

  In order to solve the above-described problems and achieve the object, the present invention provides a mold manufacturing method for manufacturing a mold used for manufacturing a casting, a wax mold manufacturing process for manufacturing a wax mold corresponding to a casting, A slurry application step of applying a first slurry to the wax mold; a step of drying the wax mold to which the first slurry is adhered; and the dried wax mold in an outer box covering the periphery of the wax mold An installation step of installing, a second slurry injection step of injecting a second slurry into the external box in which the wax mold is installed, and a solidification step of solidifying the second slurry injected into the external box. It is characterized by.

  The second slurry is preferably a mixture of delta alumina and water.

  In the second slurry, refractory particles and a polycarboxylic acid serving as a surfactant are mixed, and the refractory particles are dispersed by the surfactant, and the solidification step is performed in the second slurry. It is preferable that the alkali compound is added.

  The refractory particles are preferably mullite.

  Moreover, it is preferable that the said external box is a shape where the inner peripheral surface followed the outer periphery of the said wax type | mold.

  The first slurry preferably contains any one of silica sol, alumina, and zirconia.

  The outer box has a space of 5 mm to 30 mm between the wax mold.

  In order to solve the above-described problems and achieve the object, the present invention is a mold, which is manufactured by any one of the above-described mold manufacturing methods.

  In order to solve the above-described problems and achieve the object, the present invention provides a mold for use in the manufacture of a casting, the core having a shape corresponding to the hollow portion inside the casting, and the shape of the outer peripheral surface of the casting. The outer mold has a two-layer structure of a first layer formed on an inner peripheral surface and a second layer formed on the outer side of the first layer. It is characterized by.

  The present invention can produce a casting mold in a short time, and has an effect that a casting can be efficiently manufactured.

FIG. 1 is a flowchart showing an example of a process of a casting method. FIG. 2 is a flowchart showing an example of the steps of the mold manufacturing method. FIG. 3 is an explanatory view schematically showing a core manufacturing process. FIG. 4 is a perspective view schematically showing a part of the mold. FIG. 5 is an explanatory view schematically showing a wax mold manufacturing process. FIG. 6 is an explanatory view schematically showing a configuration in which slurry is applied to a wax mold. FIG. 7 is an explanatory view schematically showing a manufacturing process of the outer mold. FIG. 8 is an explanatory view schematically showing a part of the mold manufacturing method. FIG. 9 is an explanatory view schematically showing a partial process of the casting method.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following description. In addition, constituent elements in the following description include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in a so-called equivalent range.

  FIG. 1 is a flowchart showing an example of a process of a casting method. Hereinafter, the casting method will be described with reference to FIG. Here, the processing shown in FIG. 1 may be executed fully automatically, or may be executed by an operator operating an apparatus that executes each process. The casting method of this embodiment produces a casting mold (step S1). The mold may be prepared in advance or may be manufactured every time casting is performed.

  Hereinafter, the mold manufacturing method of the present embodiment executed in the step S1 will be described with reference to FIGS. FIG. 2 is a flowchart showing an example of the steps of the mold manufacturing method. Here, the processing shown in FIG. 2 may be executed fully automatically, or may be executed by an operator operating an apparatus that executes each process.

  The mold manufacturing method produces a core (core) (step S12). A core is a shape corresponding to the cavity inside the casting produced with a casting_mold | template. That is, the core is arranged in a portion corresponding to the cavity inside the casting, thereby suppressing the metal that becomes the casting from flowing in at the time of casting. Hereafter, the manufacturing process of a core is demonstrated using FIG. FIG. 3 is an explanatory view schematically showing a core manufacturing process. In the mold manufacturing method, a mold 12 is prepared as shown in FIG. 3 (step S101). The mold 12 has a hollow area corresponding to the core. The portion that becomes the cavity of the core becomes the convex portion 12a. In FIG. 3, the cross section of the mold 12 is shown, but the mold 12 basically covers the entire circumference of the region corresponding to the core except for the opening for injecting the material into the space and the hole for extracting air. It is hollow. In the mold casting method, the ceramic slurry 16 is injected into the mold 12 through an opening for injecting material into the space of the mold 12 as indicated by an arrow 14. Specifically, the core 18 is produced by so-called injection molding in which the ceramic slurry 16 is injected into the mold 12. In the mold manufacturing method, when the core 18 is produced inside the mold 12, the core 18 is removed from the mold 12, and the removed core 18 is placed in the firing furnace 20 and fired. Thereby, the core 18 made of ceramic is baked and hardened (step S102). In the mold casting method, the core 18 is produced as described above. The core 18 is formed of a material that can be removed by a decore process such as a chemical process after the casting is solidified.

  In the mold manufacturing method, after the core 18 is manufactured, an external mold is manufactured (step S14). The outer mold has a shape in which the inner peripheral surface corresponds to the outer peripheral surface of the casting. The mold may be made of metal or ceramic. FIG. 4 is a perspective view schematically showing a part of the mold. As for the metal mold | die 22a shown in FIG. 4, the recessed part formed in the internal peripheral surface respond | corresponds to the outer peripheral surface of a casting. In FIG. 4, only the mold 22a is shown, but a mold corresponding to the mold 22a and corresponding to the mold 22a is also produced so as to close the concave portion formed on the inner peripheral surface. In the mold manufacturing method, two molds are combined to form a mold whose inner peripheral surface corresponds to the outer peripheral surface of the casting.

  After producing the external mold, the mold manufacturing method produces a wax mold (wax mold) (step S16). Hereinafter, a description will be given with reference to FIG. FIG. 5 is an explanatory view schematically showing a wax mold manufacturing process. In the mold manufacturing method, the core 18 is installed at a predetermined position of the mold 22a (step S110). Thereafter, a mold 22b corresponding to the mold 22a is placed on the surface of the mold 22a where the recess is formed, the core 18 is surrounded by the molds 22a and 22b, and the core 18 and the molds 22a and 22b are separated. A space 24 is formed therebetween. The mold manufacturing method starts injection of WAX 28 from the pipe connected to the space 24 toward the inside of the space 24 as indicated by an arrow 26 (step S112). WAX 28 is a substance that melts (having a relatively low melting point) when heated above a predetermined temperature, such as wax. In the mold manufacturing method, the entire space 24 is filled with the WAX 28 (step S113). Thereafter, the wax 28 is solidified to form the wax mold 30 in which the WAX 28 surrounds the core 18. The wax mold 30 basically has the same shape as the casting for which the part formed by the WAX 28 is manufactured. Thereafter, in the casting manufacturing method, the wax mold 30 is separated from the molds 22a and 22b, and the gate 32 is attached (step S114). The gate 32 is a port into which molten metal, which is a metal melted during casting, is charged. As described above, the mold manufacturing method produces the wax mold 30 including the core 18 inside and formed of the WAX 28 having the same shape as the casting.

  In the mold manufacturing method, when the wax mold 30 is produced, slurry application is performed (step S18). FIG. 6 is an explanatory view schematically showing a configuration in which slurry is applied to a wax mold. In the mold manufacturing method, as shown in FIG. 6, the wax mold 30 is immersed in a storage part 41 in which the slurry (first slurry) 40 is stored and taken out. Thereby, the slurry layer (first slurry layer) 42 can be formed on the surface of the wax mold 30. Here, the slurry (first slurry) applied in step S <b> 18 is a slurry applied directly to the wax mold 30. As the first slurry 40, a slurry in which particles having a small particle diameter are dispersed is used. As the first slurry, for example, a slurry in which zirconia having a particle size of 0.3 μm is dispersed, a silica sol having a particle size of 20 nm, and a slurry in which alumina having a particle size of 0.5 μm is dispersed can be used. The first slurry 40 is preferably made of fire-resistant fine particles of about 350 mesh, such as zirconia, as flour. Moreover, when using an alumina and a zirconia for a 1st slurry, it is preferable to use polycarboxylic acid as a dispersing agent. In addition, it is preferable to add a small amount of an antifoaming agent (silicon-based substance) or a wettability improving agent, for example, 0.01% to the first slurry. By adding a wettability improving agent, the adhesion of the slurry to the wax mold can be improved.

  In the mold manufacturing method, when slurry application is performed, the slurry layer 42 formed by application is dried (step S20). In the mold manufacturing method, after the slurry layer is dried, the prepared mold is placed in an external box (step S22). Next, the slurry is injected into the outer box (step S24), and the slurry injected into the outer box is solidified (step S26). Hereinafter, a description will be given with reference to FIG. FIG. 7 is an explanatory view schematically showing a manufacturing process of the outer mold.

  In the mold manufacturing method, the wax mold 30 having the slurry layer 42 formed on the surface thereof is placed inside the external box 50 (step S120). Here, the external box 50 is a box in which a space surrounding the periphery of the wax mold 30 (the wax mold 30 on which the slurry layer 42 is formed) is formed. The outer box 50 of the present embodiment has a shape in which the shape of the inner peripheral surface is along the wax mold 30, specifically, a shape obtained by enlarging the wax mold 30 once (about 10 mm). The wax mold 30 is installed inside the external box 50 with a space 52 formed between the inner peripheral surface of the external box 50 and the wax mold 30.

  In the mold manufacturing method, when the wax mold 30 is arranged inside the outer box 50, the injection of the slurry (second slurry) 54 into the space 52 is started as indicated by the arrow 53 (step S121). In the mold manufacturing method, the slurry (second slurry) 54 is injected until the slurry is filled in the space 52, and the injected slurry (second slurry) 54 is solidified, whereby the slurry layer on the surface of the wax mold 30. A slurry layer (second slurry layer) 55 is formed on the surface of the (first slurry layer) 42 (step S122). Through the above steps, the mold manufacturing method forms a mold in which the first slurry layer 42 and the second slurry layer 55 are formed on the surface of the wax mold 30. The first slurry layer 42 and the second slurry layer 55 form the outer mold 61.

Here, the second slurry 54 is preferably a slurry that hardens in a short time after being put into the space 52. As the second slurry 54, a mixture of delta alumina and water can be used. Delta alumina is δ-phase alumina (aluminum hydroxide, Al (OH) ₃ ). Delta alumina becomes a slurry when mixed with water, and then solidifies after a certain period of time. Further, as the second slurry, a slurry in which refractory particles and polycarboxylic acid serving as a surfactant are mixed and the refractory particles are dispersed by a surfactant can be used. In this case, mullite can be used as the refractory particles. Mullite is an aluminosilicate mineral having a single chain structure, that is, a compound of aluminum oxide and silicon dioxide (3Al ₂ O ₃ .2SiO ₂ to 2Al ₂ O ₃ .SiO ₂ , or Al ₆ O ₁₃ Si ₂ ). When using polycarboxylic acid as a surfactant for the second slurry, the second slurry can be solidified by charging the second slurry into the external box 50 and then adding an alkali compound to the second slurry. The alkali compound is preferably mixed and rubbed before the second slurry is put into the external box. As the second slurry, a solution of sodium silicate (sodium silicate, Na ₂ SiO ₃ , Na ₄ SiO ₄ , Na ₂ Si ₂ O ₅ , Na ₂ Si ₄ O _9, etc.) can also be used. Also in this case, the second slurry 54 can be solidified by charging the second slurry 54 into the outer box 50 and then charging an alkali compound into the second slurry 54. As the alkali compound, limestone (CaCO ₃ ), slaked lime (Ca (OH) ₂ ), alumina cement (calcium aluminate), Portland cement (calcium silicate), or the like can be used. Further, as the second slurry, a slurry mainly composed of sodium silicate can be used. As the second slurry 54, it is preferable to use particles having a larger particle diameter than the particles dispersed in the first slurry 40. Thereby, the second slurry layer 55 formed by the second slurry 54 can be formed at low cost.

  In the mold manufacturing method, when the slurry is solidified, heat treatment is performed on the mold (step S28). Specifically, the wax between the outer mold and the core is removed, and the outer mold and the core are fired. Hereinafter, a description will be given with reference to FIG. FIG. 8 is an explanatory view schematically showing a part of the mold manufacturing method. In the mold manufacturing method, as shown in step S130, a wax mold provided with an outer mold 61 composed of the first slurry layer 42 and the second slurry layer 55 is placed in the autoclave 60 and heated. The autoclave 60 heats the wax mold provided with the outer mold 61 by filling the inside with pressurized steam. As a result, the wax forming the wax mold is melted, and the melted wax 62 is discharged from the space 64 surrounded by the outer mold 61. In the mold manufacturing method, the melted WAX 62 is discharged from the space 64, so that the space 64 is formed in the region filled with WAX between the outer mold 61 and the core 18, as shown in step S131. 72 is produced. Thereafter, in the mold manufacturing method, the mold 72 in which the space 64 is formed between the outer mold 61 and the core 18 is heated in the firing furnace 70 as shown in step S132. As a result, the mold 72 is cured by removing the water component and unnecessary components contained in the outer mold 61 and further firing. In the casting manufacturing method, the mold 72 is produced as described above.

  The description of the casting method will be continued with reference to FIGS. 1 and 9. FIG. 9 is an explanatory view schematically showing a partial process of the casting method. In the casting method, when the mold is produced in step S1, the mold is preheated (step S2). For example, the mold is placed in a furnace (vacuum furnace, firing furnace) and heated to 800 ° C. or higher and 900 ° C. or lower. By performing preheating, it is possible to prevent the mold from being damaged when molten metal (melted metal) is injected into the mold at the time of casting production.

  In the casting method, when the mold is preheated, pouring is performed (step S3). That is, as shown in step S <b> 140 of FIG. 9, the molten metal 80, that is, a molten casting material (for example, steel) is injected between the outer mold 61 and the core 18 from the opening of the mold 72.

  In the casting method, after the molten metal poured into the mold 72 is solidified, the outer mold 61 is removed (step S4). That is, as shown in step S141 of FIG. 9, when the molten metal hardens into the casting 90 inside the mold 72, the outer mold 61 is crushed and removed from the casting 90 as a broken piece 61a.

  In the casting method, when the outer mold 61 is removed from the casting 90, a core removal process is performed (step S5). That is, as shown in step S142 of FIG. 9, the casting 90 is put into the autoclave 92 and the core removal process is performed to melt the core 18 inside the casting 90, and the melted core 94 is put inside the casting 90. To discharge from. Specifically, the casting 90 is put into an alkaline solution inside the autoclave 92, and the core 94 dissolved from the casting 90 is discharged by repeating pressurization and decompression.

  In the casting method, after the core removal process is performed, a finishing process is performed (step S6). That is, finishing is performed on the surface and inside of the casting 90. In the casting method, the casting is inspected together with the finishing process. Thereby, as shown to step S143 of FIG. 9, the casting 100 can be manufactured.

  As described above, the casting method of the present embodiment produces a casting by using a lost wax casting method using WAX (wax) to produce a casting. Here, the mold manufacturing method, the casting method, and the mold of the present embodiment include an outer mold that is an outer portion of the mold, a first slurry layer (initial layer) serving as an inner peripheral surface, and a first slurry layer (initial layer). ) Of the second slurry layer (strength holding mold, strength holding layer) provided outside. Thereby, the layer structure of the outer mold can be simplified. Specifically, there is no need to repeat the three steps of slurry application, stucco (fireproof particles) spraying, and drying, and the step of forming the outer mold layer is performed twice (the formation of the first slurry layer and the second step). Formation of a slurry layer). Thereby, the production time of the mold can be shortened.

  The mold manufacturing method, the casting method, and the mold of the present embodiment use an external box, fill the second slurry between the external box and the first slurry layer, and solidify the second slurry, whereby the second slurry Forming a layer. Thereby, the 2nd slurry layer of various thickness can be formed by adjusting the shape of an external box. Thereby, a thick layer can be formed more efficiently than the step of applying slurry and spraying refractory particles (stucco) and drying. Thereby, a strong outer mold can be produced in a short time.

  In addition, the mold manufacturing method uses a material that is easy to solidify or solidifies when a predetermined treatment is performed as the second slurry, so that even when the second slurry is thickened, the second slurry can be produced in a shorter time than drying the slurry. A layer can be formed. For example, by using a mixture of delta alumina and water as the second slurry, water is added to delta alumina at the time of production to make a slurry, and then quickly put between the outer box and the first slurry layer. Thus, it can be solidified in a short time. In addition, by preparing a second slurry using polycarboxylic acid as a surfactant, the slurry can be solidified if alkali is added to the slurry. As described above, in the mold manufacturing method, the second slurry layer can be formed in a short time by using a material that is easily solidified or solidifies when a predetermined treatment is performed as the second slurry.

  The outer box preferably has a space between the wax mold and 5 mm or more and 30 mm or less. Thereby, the intensity | strength of an outer side casting mold can be made into an appropriate range, reducing the quantity of the 2nd slurry to be used.

  Moreover, in the said embodiment, since the 2nd slurry can be used efficiently, although the internal peripheral surface of the external box was made into the shape along the wax type | mold, it is not limited to this. The inner peripheral surface of the outer box may have a shape that does not follow the wax shape, for example, a rectangular shape.

(Example)
Hereinafter, the mold manufacturing method and the casting method of the present embodiment will be described using examples. In the following examples, the wax mold before the outer mold is formed is a member having a width of 30 mm, a thickness of 8 mm, and a length of 300 mm, and the first slurry layer and the second slurry layer are formed on the wax mold. A mold was prepared.

Example 1
First, high purity ultrafine zirconia (YSZ, specific surface area 20 m ² / g, particle size of about 0.3 μm) was kneaded for 24 hours using a ball mill with a dispersant as polycarboxylic acid to form a slurry. This slurry has a solid content concentration of 50 wt%. In the slurry, as a result of the dispersion treatment, it was confirmed that the zirconia particles were monodispersed in 0.3 μm. Specifically, the particle size distribution was measured using a laser diffraction particle size distribution measuring device, and it was confirmed that the particle size distribution was an average of 0.3 microns (0.2-0.4 microns).
350 mesh zircon powder was added to the prepared slurry containing zirconia. Further, a first slurry was prepared by adding 0.01% of a silicon-based substance and 0.01% of a wettability improving agent as an antifoaming agent to the slurry to which zircon powder was added.

  The slurry is attached to the surface of the wax mold (wax surface) by immersing the wax mold in the produced first slurry and then pulling it up. Thereafter, excess slurry was dropped and dried to form a first slurry layer (a first dry film of the slurry) on the wax-shaped surface (wax surface). Next, an external box designed so that the distance from the wax mold is approximately 10 mm, that is, the thickness of the second slurry layer is approximately 10 mm, and the wax mold in which the first slurry layer is formed is installed in the external box. To do.

  Next, water was added to delta alumina to make a slurry, thereby preparing a second slurry. The produced second slurry was poured into the space between the outer box and the wax mold on which the first slurry layer was formed, and left to stand for 1 hour. As a result of standing for 1 hour, the second slurry was solidified with slight heat generation. After solidification, the wax mold in which the first slurry layer and the second slurry layer were formed was taken out from the external box, dried, and then heat-treated at 1000 ° C. to produce a mold. The produced mold had the same performance as a mold in which slurry and refractory powder were repeatedly added. Thus, by producing the mold, it was possible to greatly reduce the number of manufacturing steps of the mold.

(Example 2)
First, a commercially available silica sol (SiO ₂ , particle size 20 nm, solid content concentration 30 wt%) was prepared, and 350 mesh zircon powder was added to this silica sol. Further, a first slurry was prepared by adding 0.01% of a silicon-based substance and 0.01% of a wettability improving agent as an antifoaming agent to the slurry to which zircon powder was added.

  The slurry is attached to the surface of the wax mold (wax surface) by immersing the wax mold in the produced first slurry and then pulling it up. Thereafter, excess slurry was dropped and dried to form a first slurry layer (a first dry film of the slurry) on the wax-shaped surface (wax surface). Next, an external box designed so that the distance from the wax mold is approximately 10 mm, that is, the thickness of the second slurry layer is approximately 10 mm, and the wax mold in which the first slurry layer is formed is installed in the external box. To do.

  Next, using a polycarboxylic acid as a surfactant, mullite having a particle size of 50 μm was dispersed and slurried to prepare a second slurry. 1 wt% cement powder was added to the second slurry and stirred rapidly, then poured into the space between the outer box and the wax mold on which the first slurry layer was formed, and left to stand for 1 hour. As a result of standing for 1 hour, the second slurry was solidified with slight heat generation. After solidification, the wax mold in which the first slurry layer and the second slurry layer were formed was taken out from the external box, dried, and then heat-treated at 1000 ° C. to produce a mold. The produced mold had the same performance as a mold in which slurry and refractory powder were repeatedly added. Thus, by producing the mold, it was possible to greatly reduce the number of manufacturing steps of the mold.

Moreover, even if 1 wt% slaked lime (Ca (OH) ₂ ) was added instead of cement powder as a material for solidifying the second slurry, the second slurry was solidified in about one hour.

Example 3
First, high-purity ultrafine alumina (Al ₂ O ₃ , specific surface area 10 m 2 / g, particle size of about 0.5 μm) was kneaded for 24 hours using a ball mill with a dispersant as polycarboxylic acid to form a slurry. This slurry has a solid content concentration of 50 wt%. In the slurry, as a result of the dispersion treatment, it was confirmed that the alumina particles were monodispersed at 0.5 μm. 350 mesh zircon powder was added to the prepared slurry containing alumina. Further, a first slurry was prepared by adding 0.01% of a silicon-based substance and 0.01% of a wettability improving agent as an antifoaming agent to the slurry to which zircon powder was added.

  The slurry is attached to the surface of the wax mold (wax surface) by immersing the wax mold in the produced first slurry and then pulling it up. Thereafter, excess slurry was dropped and dried to form a first slurry layer (a first dry film of the slurry) on the wax-shaped surface (wax surface). Next, an external box designed so that the distance from the wax mold is approximately 10 mm, that is, the thickness of the second slurry layer is approximately 10 mm, and the wax mold in which the first slurry layer is formed is installed in the external box. To do.

  Next, water was added to delta alumina to make a slurry, thereby preparing a second slurry. The produced second slurry was poured into the space between the outer box and the wax mold on which the first slurry layer was formed, and left to stand for 1 hour. As a result of standing for 1 hour, the second slurry was solidified with slight heat generation. After solidification, the wax mold in which the first slurry layer and the second slurry layer were formed was taken out from the external box, dried, and then heat-treated at 1000 ° C. to produce a mold. The produced mold had the same performance as a mold in which slurry and refractory powder were repeatedly added. Thus, by producing the mold, it was possible to greatly reduce the number of manufacturing steps of the mold. Thus, when alumina was used as the first slurry, the same effect as in Example 1 could be obtained.

12, 22a, 22b Mold 12a Protrusion 14, 26, 53 Arrow 16 Slurry 18 Core (core)
20, 70 Firing furnace 24, 52, 64 Space 28 WAX
30 wax type 32 gate 40 slurry (first slurry)
42 Slurry layer (first slurry layer)
50 External box 54 Slurry (second slurry)
54a Debris 55 Slurry layer (second slurry layer)
60, 92 Autoclave 62 Melted WAX
72 Mold 80 Molten metal 90, 100 Casting 94 Molten core

Claims (8)

A mold manufacturing method for manufacturing a mold used for manufacturing a casting,
A wax mold manufacturing process for manufacturing a wax mold corresponding to the casting,
A slurry application step of applying a first slurry to the wax mold;
Drying the wax mold to which the first slurry is attached;
An installation step of installing the dried wax mold in an external box covering the periphery of the wax mold;
A second slurry injection step of injecting a second slurry into the external box in which the wax mold is installed;
A solidifying step of solidifying the second slurry injected into the external box,
The mold manufacturing method, wherein the second slurry is a mixture of delta alumina and water. A mold manufacturing method for manufacturing a mold used for manufacturing a casting,
A wax mold manufacturing process for manufacturing a wax mold corresponding to the casting,
A slurry application step of applying a first slurry to the wax mold;
Drying the wax mold to which the first slurry is attached;
An installation step of installing the dried wax mold in an external box covering the periphery of the wax mold;
A second slurry injection step of injecting a second slurry into the external box in which the wax mold is installed;
A solidifying step of solidifying the second slurry injected into the external box,
In the second slurry, refractory particles and a polycarboxylic acid serving as a surfactant are mixed, and the refractory particles are dispersed by the surfactant.
The method for producing a mold, wherein the solidifying step is a treatment of adding an alkali compound to the second slurry.   The mold manufacturing method according to claim 2, wherein the refractory particles are mullite.   The said alkali compound contains at least 1 of a limestone, slaked lime, an alumina cement, and a Portland cement, The casting_mold | template manufacturing method of Claim 2 or 3 characterized by the above-mentioned.   The mold manufacturing method according to any one of claims 1 to 4, wherein the outer box has a shape in which an inner peripheral surface is along an outer periphery of the wax mold. The mold manufacturing method according to claim 5, wherein a space between the outer box and the wax mold is 5 mm or more and 30 mm or less.   The mold manufacturing method according to any one of claims 1 to 6, wherein the first slurry includes any one of silica sol, alumina, and zirconia. A mold used for manufacturing a casting,
A core having a shape corresponding to a hollow portion inside the casting,
An outer mold corresponding to the shape of the outer peripheral surface of the casting,
The outer mold has a two-layer structure of a first layer formed on an inner peripheral surface and a second layer formed on the outer side of the first layer,
The second layer includes refractory particles and an alkali compound,
The alkali compound includes at least one of limestone, slaked lime, alumina cement, and Portland cement.

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