KR20150054916A - Mold for precision casting, and method for producing same - Google Patents

Abstract

Wherein the outer mold has an outer circumferential surface corresponding to the shape of the outer circumferential surface of the casting, the outer circumferential surface of the outer circumferential surface being formed on the inner circumferential surface of the casting, (First dried film) 101A made of a slurry film made of a sol and made by using a casting mold slurry for precise casting which becomes mullite upon firing, and a prime layer (first dried film) Is formed by a slurry layer 102 made of the cast slurry for precision casting and a stucco layer 103 having a stamper material attached to the slurry layer and dried to form a first backup layer And a multi-layer backup layer 105A formed by forming a plurality of dried films (104-1).

Description

Technical Field [0001] The present invention relates to a mold for precise casting and a manufacturing method thereof,

The present invention relates to a mold for precise casting and a method for producing the same.

A casting method for producing a casting is a precision casting method used for producing a casting with high precision. In the precision casting method, as described in Patent Document 1, a slurry is applied to the periphery of a disappeared model (wax type) having the same shape as that of a molded part, and thereafter, a slurry of a first layer stucco ) Is attached and dried. Thereafter, three steps of applying slurry, attaching stucco, and drying are repeated to produce a mold (outer mold) covering the outside of the casting.

Here, as the mold for precision casting, a wax type is used for a slurry mainly composed of silica sol, and a slurry is attached to the surface of the wax type and dried.

Since the slurry to be adhered is small and can only be made thin by one operation, the thickness is made thick by repeating a number of times to several times. Further, in order to accelerate the drying or to secure the thickness quickly, coarse particles called stucco are sprayed on the surface of the slurry to prevent dry cracking. Therefore, the cross-sectional structure of the mold is composed of repetition of a dense layer and a coarse particle layer.

For example, silica sol is a liquid in which spherical silica particles having a particle diameter of about 20 nm are dispersed. This silica ultrafine particle adheres to the surface of relatively fine particles (several microns to several tens of microns) and coarse particles (stucco) (several hundred microns to several millimeters) such as zircon and alumina contained in the slurry in the course of drying, By tightly bonding by the heat treatment, the shape of the mold is maintained, and at the same time, it is used as a mold.

Japanese Patent Application Laid-Open No. 2001-18033

However, in general, a mold using silica sol (liquid in which silica ultrafine particles are dispersed) described above is sufficient. However, for example, in the production of unidirectional solidification blade, molten metal is held in order to control the crystal precipitation direction. As a result, the holding time at a high temperature (for example, about 1550 DEG C) becomes long. In this case, since the silica is retained at a high temperature, silica as a binder is softened, and the mold is deformed.

Here, in the production of unidirectional solidification blades, etc., a mold is provided in a heater in a vacuum, and is heated and held at a temperature equal to or higher than the melting point of the molten metal. Molten metal is injected into the mold to draw the mold downward from the heater The molten metal is generally produced by cooling and solidifying the molten metal from one direction below.

Therefore, for example, in the production of unidirectional solidification blades, the appearance of molds which are prevented from being deformed even when they are held at a high temperature (for example, about 1550 DEG C) for a long time is desired.

The present invention has been made in view of the above, and an object of the present invention is to provide a mold for precise casting which does not cause deformation even when it is held at a high temperature for a long time, and a method for producing the same.

A first invention of the present invention for solving the above-mentioned problems is a precision casting mold used for producing a casting, comprising: a core having a shape corresponding to a cavity portion inside the casting; and a core having a shape corresponding to the shape of the peripheral surface of the casting The outer mold has an outer mold formed on the inner circumferential surface thereof and is made of a finely divided alumina fine particle having a particle diameter of 1.0 탆 or less and a silica sol and is dried using a casting slurry for precise casting which is a mullite upon firing And a slurry layer formed on the outer side of the prime layer, the slurry layer comprising the cast slurry for precision casting, and the stator layer having the stator material adhered to the slurry layer, and drying the slurry layer And a plurality of backup layers made up of a plurality of backup layers Precision casting mold.

A second aspect of the present invention is the method according to the first aspect of the present invention, wherein the precursor casting mold slurry contains one of zircon powder and alumina powder having an average particle size of 50 탆 or less and the stator element has a zircon stator Grains and alumina stucco grains. The present invention relates to a mold for precision casting.

A third invention is the mold for precision casting according to the first or second invention, wherein the prime layer has a stucco layer having a stucco material adhered to a slurry layer made of the precursor casting mold slurry.

The fourth invention is a process for producing a casting mold for precision casting, which is used in the production of a casting, characterized in that the lead casting for precision casting is composed of alumina ultrafine particles consisting of a single dispersion of a particle diameter of 1.0 탆 or less and silica sol, A first film forming step of immersing the casting mold slurry in a casting mold slurry, pulling it up, and drying it to form a prime layer composed of a slurry film on the lead type surface; , A second film forming step of forming a backup layer by sprinkling the stator material on the surface of the slurry after being pulled up and then drying the same and a step of forming a backup layer in the second film forming step are repeated a plurality of times to form a multi- A dewaxing step of melting and removing the lead-type wax from the obtained molded article, a dewaxing step of dewaxing the dewaxed wax, And a subsequent firing step of firing the formed body to obtain a mold. The present invention also provides a method for producing a mold for precision casting.

A fifth aspect of the present invention is the precise casting method according to the fourth aspect of the present invention, wherein a stucco layer is formed by adhering the stucco material to the slurry layer made of the cast slurry for precision casting in the first film forming step, This is a method for producing a quiet mold.

The sixth invention is the process for producing a mold for precision casting according to the fourth or fifth invention, wherein the dispersant of the cast slurry for precision casting is a polycarboxylate.

In the present invention, by using alumina fine particles to be mullite having high heat resistance and silica sol to make a slurry, the heat resistance temperature is improved with respect to the use of the conventional silica sol. For example, A mold having no deformation even when it is held for a long period of time at 1550 ° C) can be obtained.

1 is a structural view of a dry molded article to be an outer mold,
Fig. 2 is a diagram showing the structure of another dry molded article to be an outer mold,
3 is a flowchart showing an example of a process of a casting method,
4 is a flowchart showing an example of a process of the mold manufacturing method,
5 is an explanatory diagram schematically showing a manufacturing process of a core,
6 is a perspective view schematically showing a part of a mold,
7 is an explanatory view schematically showing a manufacturing process of a lead-type,
8 is an explanatory view schematically showing a configuration in which a slurry is applied in a lead-
Fig. 9 is an explanatory view schematically showing the manufacturing process of the outer mold,
Fig. 10 is an explanatory diagram schematically showing some steps of a mold manufacturing method,
11 is an explanatory view schematically showing some steps of a casting method.

Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited by the following description. The constituent elements in the following description include those that can be readily devised by those skilled in the art, substantially the same, and so-called equivalents.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a configuration diagram of a dry molded article to be an outer mold. Fig. 2 is a configuration diagram of another dry molded article to be an outer mold. As shown in Fig. 1, a precision casting mold is a precision casting mold used for producing a casting, and has a core having a shape corresponding to a cavity portion inside the casting, and a core having a shape corresponding to the shape of the outer periphery of the casting The outer mold is formed on the inner circumferential surface. The outer mold is made of the alumina ultrafine particles and the silica sol which are formed by a single dispersion of a particle diameter of 1.0 占 퐉 or less (very suitably 0.3 占 퐉 to 0.5 占 퐉 in the embodiment) (First dried film) 101A made of a slurry film obtained by drying a cast slurry for precise casting which becomes a light source, and a slurry film formed on the outside of the prime layer (first dried film) 101A, A slurry layer 102 made of a cast slurry for precise casting, and a stoker layer 103 having a stuck material adhered to the slurry layer, And a multi-layer backup layer 105A formed by forming a plurality of backup layers (second dried films) 104-1.

Here, in the present invention, alumina fine particles (alumina ultrafine particles) of a high purity ultrafine particle, which is a binder for forming a slurry, are dispersed in a single ball mill using a dispersing means such as a ball mill.

Here, the monodispersed state refers to a state in which the slurry is formed using alumina fine particles having a particle diameter of about 0.5 mu m, and the result of the dispersion treatment is that the particles are monodispersed at 0.5 mu m.

Here, the particle size of the alumina fine particles is preferably 1.0 占 퐉 or less, and more preferably 0.3 占 퐉 to 0.6 占 퐉.

In the present invention, it is preferable that the alumina fine particles have a particle size of 1.0 탆 or less. If the average particle size exceeds 1.0 탆, the result of the bending test strength is undesirable.

Here, as a dispersant for monodispersing, for example, a polycarboxylate (for example, ammonium salt) is used to disperse.

As the dispersing means, for example, a ball mill using a ball having a diameter of 10 mm to 20 mm can be exemplified, but the ball mill is not limited to this as long as it is a means for single dispersion.

In the present invention, it is necessary to form a good slurry in which alumina fine particles as a binder are monodispersed.

Further, in the present invention, it is easy to form mullite uniformly at the time of firing. For example, it is preferable that the mixing ratio of alumina fine particles dispersed in a single dispersion of 0.5 mu m is large.

Here, the alumina particle diameter is preferably 1.0 mu m or less, more preferably 0.3 mu m to 0.6 mu m.

The blending ratio is preferably set in the following range.

Al ₂ O ₃ / SiO ₂ = 1.5 (molar ratio)

The silica sol is a uniform dispersion of 0.02 占 퐉 silica and is uniformly dispersed in the alumina slurry.

In the present invention, since alumina fine particles having a predetermined particle size are uniformly dispersed, the reactivity with the silica sol in the firing step becomes favorable, and mullite can be formed at a temperature lower than normal (for example, 1,000 DEG C) It becomes.

In the case of using the alumina fine particles alone as the cast slurry for precise casting, the production cost is high because the alumina fine particles are expensive. Therefore, as in the present invention, when silica sol is added to alumina fine particles and mullite is used at the time of firing, the production cost can be reduced.

A zircon powder (for example, 350 mesh) is added as a flower to the slurry of the monodispersed alumina fine particles to which a silica sol is added to obtain a mold slurry for precision casting.

Further, in the present invention, the case where no flower is added may be allowed.

Next, a method for producing a mold for precise casting will be described with reference to Figs. 1 and 2. Fig.

(First film forming step)

First, in this first film forming step, a precursor casting mold slurry (hereinafter referred to as " slurry ") made of monolithic alumina ultrafine particles having a particle diameter of 1.0 탆 or less and silica sol, The lead type die 30 is immersed and lifted, and the excess slurry is dropped. Thereafter, by drying, a slurry film (first dried film) is obtained on the surface of the lead type die 30. This slurry film becomes the prime layer 101A which is in contact with the surface of the lead type mold 30 in Fig.

(Second film forming step)

Then, the lead type mold 30 having the prime layer 101A is immersed in the slurry, then the mold is pulled up, and the excess slurry is dropped to form a slurry layer (second layer) 102. Next, Zircon stucco particles (average particle size of 0.8 mm) were sprayed as stucco material to the wetted slurry layer (second layer) 102 and stuccoed to form a stucco layer 103 (first layer) 103 ). A laminated body of the slurry layer (second layer) 102 and the stako layer (first layer) 103 is dried to form a first backup layer (second dried film) (first drying layer) 101A on the prime layer 104-1.

(Molded body forming step)

The same operation as the second film formation step of the first backup layer 104-1 is repeated a plurality of times (for example, six times to ten times) to form the slurry layer (n + 1th layer) 102 and the stucco layer ) 103 are alternately stacked and have a multi-layer backup layer 105A of a predetermined thickness.

The dried molded article is placed in, for example, an autoclave at 150 ° C, and the wax constituting the lead type die 30 is melted and discharged.

Thereafter, this mold is heat-treated at 1,000 DEG C to obtain a mold for precision casting in which the slurry constitutes mullite.

The precision casting mold thus obtained was free from deformation and high in strength even at the temperature of 1,500 캜 as shown in the following test example. On the other hand, in the case of using a conventional silica sol, the softening behavior was confirmed.

2, a stamper material is adhered to the prime layer 101a to form a prime stamper layer 101b in the prime layer 101B and then dried to form the prime layer 101B, .

When the stamper material is adhered like the prime layer 101B, the number of times of stacking the slurry layer of the multi-layer backup layer 105B and the number of times of stacking the stamper layer 103 are the same (n layers) Thereby obtaining a dried molded article 106B to be an outer mold having the multi-layered backup layer 105B.

In the present invention, zircon powder is used as a flower, but alumina powder is used in addition to zircon powder, and the same precision casting mold can be obtained even when alumina stucco particles are used instead of zircon stucco particles as stucco material.

Further, the relationship between the flower and the stucco material is not limited, and either zircon powder or alumina powder may be used as a flower, and zircon stucco particles or alumina stucco particles may be used as the stucco material.

The diameter of the flower is 350 mesh, but the present invention is not limited to this. For example, particles having a diameter of about 5 to 80 mu m and an average particle diameter of 50 mu m or less are preferably used Do.

The particle size of the stucco particles is 0.8 mm. However, the present invention is not limited to this. For example, particles of about 0.4 mm to 2 mm and particles having an average particle diameter of 0.5 mm or more may be used desirable.

Hereinafter, a casting method using the precise casting mold of the present invention will be described.

3 is a flowchart showing an example of a process of the casting method. Hereinafter, the casting method will be described with reference to Fig. Here, the processing shown in Fig. 3 may be performed fully automatically, or the operator may operate the apparatus for executing each step. The casting method of this embodiment forms a mold (step S1). The mold may be prepared in advance or may be produced each time casting is carried out.

Hereinafter, with reference to Figs. 4 to 10, a description will be given of a mold manufacturing method of the present embodiment to be executed in the step S1. Fig. 4 is a flowchart showing an example of a process of the casting mold manufacturing method. Here, the processing shown in Fig. 4 may be performed fully automatically, or the operator may operate the apparatus for executing each step.

The mold manufacturing method produces a core (core) (step S12). The core is in a shape corresponding to the cavity inside the casting made from the casting mold. That is, the core is disposed at a portion corresponding to the cavity inside the casting, thereby suppressing the flow of the casting metal during casting. Hereinafter, with reference to Fig. 5, the manufacturing process of the core will be described. 5 is an explanatory view schematically showing a manufacturing process of a core. In the mold manufacturing method, the mold 12 is prepared as shown in Fig. 5 (step S101). The mold 12 has a cavity corresponding to the core. The convex portion 12a becomes a cavity portion of the core. Although the mold 12 is shown in the cross section of the mold 12 in Fig. 5, the mold 12 is provided with a cavity which basically covers the four corners of the region corresponding to the core, Respectively. The mold casting method is such that the ceramic slurry 16 is injected into the mold 12 from the opening for injecting the material into the space of the mold 12 as indicated by the 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. The core 18 is separated from the metal mold 12 after the core 18 is formed in the metal mold 12 and the separated core 18 is provided in the firing furnace 20 so as to be subjected to firing . Thereby, the core 18 formed of ceramics is sintered (step S102). The casting method of the casting mold 18 is as described above. Further, the core 18 is formed of a material which is removed by decoupling treatment such as chemical treatment after the cast is hardened.

In the mold manufacturing method, after the core 18 is manufactured, the outer mold is manufactured (step S14). The outer peripheral surface of the outer mold has a shape corresponding to the outer peripheral surface of the casting. The mold may be formed of a metal or ceramic. 6 is a perspective view schematically showing a part of a mold. In the mold 22a shown in Fig. 6, the concave portion formed on the inner circumferential surface corresponds to the outer circumferential surface of the casting. Although only the mold 22a is shown in Fig. 6, a mold corresponding to the mold 22a is also prepared in a direction closing the recess formed in the inner circumferential surface, corresponding to the mold 22a. In the casting mold manufacturing method, two molds are fitted so that the inner circumferential surface corresponds to the outer circumferential surface of the casting.

In the casting mold manufacturing method, an outer mold is manufactured and then a lead-type mold (wax mold) is produced (step S16). The following description will be made with reference to FIG. 7 is an explanatory view schematically showing a manufacturing process of a lead-type. In the mold manufacturing method, the core 18 is provided at a predetermined position of the mold 22a (step S110). Thereafter, the metal mold 22b corresponding to the metal mold 22a is covered on the surface of the metal mold 22a on which the concave portion is formed, so that the periphery of the core 18 is surrounded by the molds 22a and 22b, And a space 24 is formed between the molds 22a and 22b. The mold manufacturing method starts the injection of the WAX 28 from the piping connected to the space 24 toward the interior of the space 24, as indicated by the arrow 26 (step S112). The WAX 28 is a material having a relatively low melting point, for example beeswax, which melts when heated to a predetermined temperature or higher. In the casting mold manufacturing method, the entire space 24 is filled with the WAX 28 (step S113). Thereafter, the wax 28 is solidified to form the wand 30 surrounding the core 18 around the wax 28. [ The lead type die 30 has basically the same shape as the casting intended for the portion formed by the WAX 28. [ Thereafter, in the casting manufacturing method, the lead type die 30 is separated from the dies 22a, 22b and the die spindle 32 is mounted (step S114). The sprue 32 is an inlet into which molten metal, which is a molten metal, is injected during casting. The mold manufacturing method is as described above, and the lead type die 30 formed of the WAX 28 including the core 18 and having the same shape as the casting is manufactured.

In the casting mold manufacturing method, the lead type casting mold 30 is manufactured and then the slurry is applied (dipping) (step S18). 8 is an explanatory view schematically showing a configuration in which a slurry is applied to a lead type. As shown in Fig. 8, the casting mold 30 is immersed in the storage section 41 in which the slurry 40 is stored, and is then taken out, followed by drying (step S19). Thereby, the prime layer 101A can be formed on the surface of the lead type die 30.

Here, the slurry to be applied in step S18 is a slurry directly applied to the lead type die 30. [ The slurry (40) is a cast slurry for precise casting which is composed of alumina ultrafine particles and silica sol and becomes mullite upon firing. As the flour, it is preferable to use refractory fine particles of about 350 mesh, for example, zirconia, in the slurry (40). Further, it is preferable to use a polycarboxylic acid salt as a dispersant. It is preferable that a small amount, for example, 0.01% of an antifoaming agent (silicon-based material) or a wettability improver is added to the slurry 40. Adhesion of the slurry (40) to the lead (30) can be improved by adding the wettability improving agent.

As shown in Fig. 8, the slurry is coated with the slurry 40 and dried to again apply slurry (dipping) to the lead type having the prime layer (first dried film) 101A Step S20). As shown in Fig. 9, stuccoing is carried out by spraying zircon stucco particles (average particle size 0.8 mm) as the stucco material 54 on the surface of the wet slurry (step S21). Thereafter, the stuck coat adhered to the surface of the slurry layer was dried to form a first backup layer (second dried film) 104-1 on the prime layer (first dried film) 101A (Step S22) .

(N: 6 to 10 times) the same operation as that for forming the first backup layer (second dried film) 104-1 (step S23). The n pre-formed backup layer 104-n of the predetermined number of times (n) is laminated (step S23: YES), and a dry formed article 106A ).

In the casting mold manufacturing method, a dry molded body 106A in which a plurality of layers of a prime layer 101A and a multi-layer backup layer 105A are formed is subjected to a heat treatment on the dried molded body 106A (step S24). More specifically, the WAX between the outer mold and the core is removed, and the outer mold and the core are again fired. This will be described below with reference to FIG. Fig. 10 is an explanatory view schematically showing some steps of the mold manufacturing method. The mold manufacturing method is a method in which a dry molded body 106A to be an outer mold having a plurality of layers of a prime layer 101A and a multi-layer backup layer 105A is placed in an autoclave 60, as shown in step S130, do. The autoclave 60 heats the lead type die 30 in the dry formed body 106A by filling the inside with pressurized steam. As a result, the WAX constituting the lead type 30 is melted and the dissolved WAX 62 is discharged from the space 64 surrounded by the dry molded body 106A.

The mold manufacturing method is a method in which the molten WAX 62 is discharged from the space 64 so that the area where the WAX between the dry molded body 106A serving as the outer mold and the core 18 A mold 72 having a space 64 formed therein is fabricated. Thereafter, as shown in step S132, the mold manufacturing method heats the mold 72, in which the space 64 is formed between the dry molded body 106A and the core 18, as the outer mold, in the baking furnace 70, as shown in step S132. As a result, the casting mold 72 is cured by removing the water component and unnecessary components contained in the dried molded product 106A to be the outer mold, and further fired to form the outer mold 61. [ The casting mold 72 is manufactured as described above.

The description of the casting method will be continued using Figs. 3 and 11. Fig. Fig. 11 is an explanatory view schematically showing some steps of the casting method. In the casting method, when a mold is manufactured 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. The preheating can prevent the mold from being damaged when the molten metal (molten metal) is injected into the mold at the time of manufacturing the casting.

In the casting method, the mold is preheated and pouring is performed (step S3). That is, as shown in step S140 in FIG. 11, the molten metal 80, that is, the molten cast material (for example, steel) is injected from the opening of the mold 72 into the space between the outer mold 61 and the core 18 do.

The casting method is to solidify the molten metal 80 along with the mold 72 and then to remove the outer mold 61 (step S4). That is, as shown in step S141 of FIG. 11, when the molten metal 80 hardens in the mold 72 and becomes the casting 90, the outer mold 61 is crushed and removed from the casting 90 as fragments 61a Separated.

In the casting method, the outer mold 61 is removed from the casting 90, and then the decoupling treatment is performed (step S5). That is, as shown in step S142 of FIG. 11, the core 90 inside the casting 90 is melted by performing the decoupling treatment by inserting the casting 90 into the autoclave 92 , And the molten dissolving core 94 is discharged from the inside of the casting 90. Concretely, the casting 90 is put into the alkaline solution in the autoclave 92, and the molten core 94 is discharged from the casting 90 by repeating the pressurization and depressurization.

In the casting method, a decolorizing treatment is performed and then a finishing treatment is performed (step S6). That is, the surface or the interior of the casting 90 is subjected to a finishing treatment. Further, in the casting method, the inspection of the casting is carried out together with the finishing treatment. As a result, as shown in step S143 of Fig. 11, the casting 100 can be manufactured.

In the casting method of the present embodiment, casting is made by using a cast wax casting method using WAX (wax) as described above. Here, in the casting method, the casting method, and the casting mold of the present embodiment, the outer mold that is a portion of the outer side of the casting mold is used as a slurry and a prime layer (first dry film as a first layer) 101A serving as an inner circumferential surface by using zirconia ultra- And a plurality of backup layers 105A are formed outside the prime layer 101A. As described above, the prime layer 101B made of the prime stoker layer 101b and the prime slurry layer 101A to which the stator element is added may be used as the prime layer (see Fig. 2).

(Example 1)

Hereinafter, the casting method and the casting method of the present embodiment will be described using the embodiments. In the following examples, the lead type before the outer mold was formed was a member having a width of 30 mm, a thickness of 8 mm, and a length of 300 mm, and a prime layer (first dried film) composed of the lead type slurry layer, A multi-layer backup layer made of a stamper material was formed to prepare a mold.

A slurry of high purity ultrafine alumina (Al ₂ O ₃ , specific surface area of 10 m 2 / g, particle size of about 0.5 μm) was dispersed by using a polycarbonate as a dispersant and kneaded using a ball mill for 24 hours to form a slurry Respectively. The solid content concentration of the obtained alumina slurry was 30 wt%.

In this alumina slurry, as a result of the dispersion treatment, it was confirmed that the alumina particles were uniformly dispersed at 0.5 mu m.

Further, to prepare a silica sol (SiO _2, particle diameter 0.02㎛, solid concentration 30%).

During firing, the alumina slurry: silica sol = 306: 120 (molecular weight of 3Al ₂ O ₃ = 3 × 102 = 306, molecular weight of 2SiO ₂ = 2 × 60 (3Al ₂ O ₃ · 2SiO ₂ ) = 120). The slurry was previously combined.

At this time, occurrence of precipitation was not confirmed even when mixed.

To this blended slurry, zircon powder of 350 mesh was added as a flower to obtain a mold slurry for precision casting.

At the same time, 0.01% of silicone and 0.01% of wettability improver were added as a defoaming agent to obtain a slurry for use.

A wax body having a width of 30 mm, a thickness of 8 mm and a length of 300 mm was prepared, the wax body was immersed in the obtained slurry, and the used slurry was attached to the surface of the wax and then the excess used slurry was dropped and dried Thereby obtaining a prime layer (first dried film) of the slurry on the surface of the wax body.

Next, in order to obtain the second dried film, the wax body having the prime layer was immersed in the slurry and then pulled up to drop the excess used slurry.

Zircon stucco particles having an average particle size of 0.8 mm were adhered to the wet slurry and then dried to form a second dried film (first backup layer).

The same operation as the formation of the second dried film (first backup layer) was repeated six times to obtain a molded article having a thickness of about 10 mm and having a multi-layered backup layer.

The obtained dry molded article was placed in an autoclave at 150 캜, and the wax was melted and discharged.

Then, this mold was heat-treated at 1000 ° C to obtain a mold of Example 1.

[Comparative Example]

For the sake of comparison, the same operations as those of the examples were carried out using a slurry using the same silica sol (liquid in which spherical silica particles having a particle size of about 2 nm was dispersed), which was the same as the conventional one,

[exam]

From the obtained molds of Example 1 and the molds of the comparative examples, strength test pieces each having a size of 10 mm x 50 mm and a thickness of 5 mm were processed and subjected to a high temperature strength test.

In the strength test at 1500 캜, the behavior of softening was confirmed in the case of using a conventional silica sol.

As a result, cutting of the test piece of the comparative example was not clear but bent. On the other hand, this embodiment mullite _{(3Al 2 O 3 · 2SiO 2} ) The test piece used for the slurry (zircon particles as a master kojae) of the formulation that is without any modification, there was a breakage (破斷) in 100㎫.

Here, the strength test was carried out in accordance with "Flexural strength of ceramics (1981)" according to JIS R 1601.

According to the results of this test, when the binder is used as a slurry which becomes mullite having a high heat resistance (melting point 1,885 ° C) at firing and zircon particles (melting point 2,715 ° C) as the stator material, A mold was obtained in which the temperature was improved and deformation did not occur even when the unidirectional solidification blade was held at a high temperature (1550 DEG C) for a long time.

(Example 2)

In Example 1, 350 mesh alumina powder was added as a flower in place of zircon powder to obtain a mold slurry for precision casting.

A mold of Example 2 was obtained in the same manner as in Example 1 except that alumina stucco particles having an average particle diameter of 0.8 mm were used as the stucco material.

[exam]

From the obtained molds of Example 2 and the molds of the comparative examples, strength test pieces each having a size of 10 mm x 50 mm and a thickness of 5 mm were processed and subjected to the same high temperature strength test as in Example 1.

The test piece using the slurry to be mullite (alumina particles as the stucco material) of this example was free from deformation and had a fracture at 100 MPa.

According to the result of the test, the binder is made into a slurry which becomes a mullite having a high heat resistance (melting point 1,885 ° C) upon firing and an alumina particle (melting point 2,070 ° C) The temperature was improved, and a mold was obtained in which deformation did not occur even at the high temperature (1550 DEG C) in the production of the unidirectional solidification blade.

From the above, it can be seen that the slurry for precision casting is made of zircon powder or alumina powder as a slurry, which is composed of alumina ultrafine particles and silica sol which are monodispersed with a particle diameter of 1.0 탆 or less and which becomes mullite having high heat resistance at firing, It is possible to obtain a mold in which the heat resistance temperature of the obtained mold is improved and the mold is not deformed even when it is held at a high temperature (1,550 DEG C) for a long time in the production of the unidirectional solidifying blade there was.

12, 22a, 22b: mold 12a:
14, 26: arrow 16: ceramic slurry
18: core (core) 20, 70: baking furnace
24, 64: Space 28: WAX (beeswax)
30: lead type 32: sprue
40: slurry 60, 92: autoclave
61: outer mold 61a: fragment
62: Dissolution WAX 72: Mold
80: molten metal 90, 100: casting
94: dissolution core 101A, 101B: prime layer
102: Slurry layer 103: Stoker layer
104-1: first backup layer 104-n first backup layer
105A and 105B: a multi-layer backup layer

Claims (6)

In a mold for precision casting used in the production of a casting,
A core having a shape corresponding to a cavity portion inside the casting,
And an outer mold corresponding to the shape of the outer circumferential surface of the casting,
The outer mold has a prime layer formed of a slurry film which is formed on the inner circumferential surface and is made of a slurry of fine alumina fine particles having a particle diameter of 1.0 탆 or less and silica sol and which is dried using a precision casting slurry for mulling at firing and,
A plurality of backup layers formed on the outer side of the prime layer and formed by a slurry layer made of the cast slurry for precise casting and a stator layer having a stator material adhered to the slurry layer and dried, And a backup layer.
Precision casting molds. The method according to claim 1,
Wherein the precursor casting mold slurry contains either zircon powder or alumina powder having an average particle size of 50 mu m or less,
Characterized in that the stator core material is any one of zircon stucco particles and alumina stucco particles having an average particle diameter of 0.5 mm or more
Precision casting molds. 3. The method according to claim 1 or 2,
Characterized in that the prime layer has a stucco layer to which a stucco material is adhered in a slurry layer made of a cast slurry for precision casting
Precision casting molds. 1. A method for producing a mold for precision casting, which is used for producing a casting,
Precise casting lead type is immersed in a cast slurry for precise casting which is composed of alumina ultrafine particles and silica sol which are monodispersed with a particle size of not more than 1.0 탆 and which becomes mullite upon firing and is pulled up and dried to obtain a slurry film A first film forming step of forming a prime layer composed of a first film,
A second film forming step of immersing the lead type mold having the prime layer formed thereon in a mold slurry for precise casting and pulling up the resin, then spraying the stucco material on the surface of the slurry,
A step of forming a backup layer in the second film formation step is repeated a plurality of times to form a molded body having a multi-layer backup layer formed thereon,
A dewaxing step of melting and removing the lead-type wax from the obtained molded article,
And a firing step of firing the dewaxed molded body to obtain a mold,
Method for manufacturing molds for precision casting. 5. The method of claim 4,
Characterized in that, in the first film forming step, a stucco material is adhered to the slurry layer made of the cast slurry for precision casting to form a stucco layer, and then the stucco layer is dried
Method for manufacturing molds for precision casting. The method according to claim 4 or 5,
Characterized in that the dispersant of the cast slurry for precision casting is a polycarboxylic acid salt
Method for manufacturing molds for precision casting.

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