JP2019188426A - Core built-in mold production method, method for producing casting, and core built-in mold - Google Patents

Abstract

To provide a core built-in mold production method where, upon production of a casting having a cavity such as the circulation passage of a cooling medium in a gas turbine rotor blade for example using a core and a mold, the thinning of the casting is attained.SOLUTION: A core built-in mold production method comprises: a core built-in mold molding step where slurry SL made into a ceramic by being solidified into a space between a metal mold 8 and a resin model 1 having an outer face part forming an outer face with a shape same as the outer face of a casting as a product and an inner face part as a molding face forming a core is injected to mold a core built-in mold made of a core and a mold structure; and a mold firing step where the core and the mold structure are heated and fired, and further, the resin model 1 is removed.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a core-integrated mold manufacturing method, a casting manufacturing method, and a core-integrated mold.

For example, the blades of a gas turbine are exposed to hot working gas. Accordingly, in order to keep the temperature of the moving blade lower, the moving blade is cooled by flowing a cooling medium inside the moving blade.
An internal cooling structure is provided in the gas turbine rotor blade in order to allow the cooling medium to flow inside. For the production of such a gas turbine blade, it is common to use precision casting. When manufacturing a gas turbine rotor blade having an internal cooling structure using precision casting, a core (core) having the same shape as the flow path of the cooling medium is disposed, and the core is removed after casting ( For example, see Patent Document 1.)

  As a method for manufacturing such a core, an injection molding using a mold and a slip casting method in which molding is directly performed from a slurry are known. On the other hand, in order to improve performance, the internal cooling structure is complicated and miniaturized. As an alternative to these manufacturing methods, for example, a complex and fine core is manufactured using a molding apparatus such as a 3D (three-dimensional) printer. Resin 3D additive manufacturing has been attempted.

JP 2002-28751 A

  By the way, when the core and the mold are made of different materials, a difference in the linear expansion coefficient between the core and the mold causes a difference in elongation at each stage in the casting process. Thus, a clearance between the mold and the core is set. That is, there is a problem that it is necessary to allow for a dimensional tolerance in consideration of the misalignment of the core, which makes it difficult to reduce the thickness of the casting.

  An object of the present invention is to provide a core-integrated mold manufacturing method, a casting manufacturing method, and a core-integrated mold that can reduce the thickness of a casting.

  According to the first aspect of the present invention, a core-integrated mold manufacturing method includes a mold, an outer surface portion that forms the outer surface of the same shape as the outer surface of a casting that is a product, and a molding surface that forms a core. A core-integrated mold molding process for injecting a slurry that becomes a ceramic by solidifying between a resin model having an inner surface portion and molding a core-integrated mold composed of the core and the mold structure And a mold firing step for heating and firing the core and the mold structure and removing the resin model.

  According to such a configuration, by integrally molding the mold and the core with the same material, there is no difference in the linear expansion coefficient between the mold and the core, and the linear expansion coefficient between the mold and the core is different. The clearance between the set mold and the core can be reduced, and the casting can be thinned.

  In the above core-integrated mold manufacturing method, the resin model may have a plurality of spaces defined between the outer surface portion and the inner surface portion.

In the above-described core-integrated mold manufacturing method, at least a part of the plurality of spaces may be arranged in a lattice shape.
According to such a structure, the expansion | swelling part at the time of resin expansion | swelling can be absorbed.

In the core-integrated mold manufacturing method, the resin model may be formed of a resin having a melting point of 190 ° C. or higher.
According to such a configuration, when a mold is manufactured using this resin model, the strength can be ensured up to an atmospheric temperature of about 190 ° C.

In the core-integrated mold manufacturing method, the resin model may be made of a 3D additive manufacturing material.
According to such a configuration, it is possible to easily form a three-dimensional shape that is difficult to form with existing technology.

  In the core-integrated mold manufacturing method, in the core-integrated mold making process, the slurry is injected after a predetermined time elapses after the first injection process of injecting the slurry and the first injection process. A second injection step.

  According to such a configuration, when the slurry is injection-molded, the filling property of the slurry can be improved.

  In the core-integrated mold manufacturing method, in the core-integrated mold making process, a fixing member that holds the position of the mold may be disposed between the resin model and the mold.

  According to such a configuration, the resin member can be prevented from being displaced at the time of injection molding by preliminarily filling the fixing member in a part between the resin model and the mold.

  In the core-integrated mold manufacturing method, the fixing member may be a green body.

In the core-integrated mold manufacturing method, the fixing member may be a bolt.
According to such a configuration, the resin model can be fixed using general-purpose parts. Further, the position of the bolt can be easily adjusted.

  According to the second aspect of the present invention, in the casting manufacturing method, the casting is precisely cast using the core-integrated mold manufactured by any one of the above-described core-integrating mold manufacturing methods.

  According to the third aspect of the present invention, the core-integrated mold includes a core and a mold structure formed of the same material as the core and connected to the core.

  According to such a configuration, by integrally molding the mold and the core with the same material, there is no difference in the linear expansion coefficient between the mold and the core, and the linear expansion coefficient between the mold and the core is different. The clearance between the set mold and the core can be reduced, and the casting can be thinned.

In the core-integrated mold, the material may be a ceramic obtained by solidifying a slurry containing 60% by mass or more of silica.
According to such a structure, it can be set as a highly meltable slurry.

  In the core-integrated mold, the slurry may contain an inorganic binder.

  According to the present invention, by integrally molding the mold and the core with the same material, there is no difference in the linear expansion coefficient between the mold and the core, and the linear expansion coefficient between the mold and the core is set differently. The clearance between the cast mold and the core can be reduced, and the casting can be thinned.

It is a flowchart of the manufacturing method of the core integrated mold according to the first embodiment of the present invention. It is sectional drawing of the resin model of 1st embodiment of this invention. It is the schematic explaining the core integral mold casting process of 1st embodiment of this invention. It is sectional drawing of the core integral type | mold mold of 1st embodiment of this invention. It is sectional drawing of the core integral type | mold mold of 1st embodiment of this invention. It is a flowchart of the manufacturing method of the casting of 1st embodiment of this invention. It is the schematic explaining the core integral mold molding process of 2nd embodiment of this invention. It is the schematic explaining the core integral mold casting process of the modification of 2nd embodiment of this invention. It is the schematic explaining the core integral mold casting process of the modification of 2nd embodiment of this invention.

[First embodiment]
Hereinafter, a core-integrated mold, a core-integrated mold manufacturing method, and a casting manufacturing method according to a first embodiment of the present invention will be described in detail with reference to the drawings.
The core-integrated mold of the present embodiment is a mold used for precision casting, for example, a mold for a gas turbine rotor blade (casting) having a cooling medium flow passage that is an internal cooling structure.

  The mold manufacturing method of this embodiment manufactures a resin model 1 having a shape equivalent to the shape of a product (casting) using a resin 3D additive manufacturing method, and uses a resin model 1 and a mold to form a core and a mold. Is characterized by being integrally formed of the same material. The core has a shape corresponding to a cavity inside a casting manufactured by a mold. The core is arranged in a portion corresponding to the cavity inside the casting, thereby suppressing the metal that becomes the casting from flowing during casting.

  As shown in FIG. 1, the core-integrated mold manufacturing method of this embodiment includes a mold manufacturing step S <b> 11 for manufacturing a mold 8 (see FIG. 3), and a slurry SL that forms the core 3 and the mold structure 11. The slurry generation step S12 for generating the resin model, the resin model formation step S13 for forming the resin model 1, and the slurry SL is supplied to the mold 8 (the hollow portion V1 of the resin model 1) on which the resin model 1 is set. A core-integrated mold forming step S14 for forming the core 3 and the mold structure 11 by curing and drying, and a core / mold-integrated baking step S15 for baking the core 3 and the mold structure 11 (a mold baking step) ) And.

The mold manufacturing step S11 is a process for manufacturing a mold 8 as a mold. The mold 8 is manufactured so that a space of about 10 mm is formed between the inner surface of the mold 8 and the outer surface of the resin model 1 when the resin model 1 is disposed inside the mold 8.
The slurry generation step S12 is a step of generating the slurry SL that becomes the core 3 and the mold structure 11 formed from ceramics by solidifying.
The slurry SL is a kneaded product of silica powder and an inorganic binder. Specifically, the slurry SL contains 60% by mass or more of silica, and can be generated by dissolving a dispersant, an inorganic binder, a crosslinking agent, and water.

Resin model formation process S13 is a process of forming the resin model 1 formed from resin using the resin 3D additive manufacturing method.
As shown in FIG. 2, the resin model forming step S13 includes an inner / outer surface molding step S13A for molding an outer surface portion 7a that forms the outer surface of the resin model 1 and an inner surface portion 7b that forms the inner surface of the resin model 1. Yes. Further, the resin model forming step S13 includes a space portion forming step S13B that defines at least one space S between the outer surface portion 7a and the inner surface portion 7b.

  The resin 3D additive manufacturing method is a method of modeling an object having a three-dimensional shape using a molding apparatus such as a 3D (three-dimensional) printer. The 3D printer can easily form a three-dimensional shape that is difficult to form with existing technology without requiring a costly mold 8 or jig.

  Moreover, as the resin 3D additive manufacturing method, a slurry additive manufacturing technique using a slurry in which ceramic fine particles are dispersed in a photocurable or thermosetting liquid resin can also be employed. The slurry additive manufacturing technique is a technique in which photo-curing or thermo-curing is generated in a limited region by laser irradiation to form a two-dimensional cross section having an arbitrary shape, and a three-dimensional shaped molded body is obtained by repeating this.

The resin model 1 has a function as a mold of the core 3 and is a structure that forms an outer shape of a casting (gas turbine blade) that is a product.
The molding surface formed by the inner surface portion 7 b has a shape that follows the core 3. In other words, the resin model 1 is formed so that the slurry has the shape of the core 3 by pouring the slurry into the cavity V <b> 1 of the resin model 1.
The outer surface portion 7a of the resin model 1 is formed so as to have the same shape as a casting that is a product.

  The resin model 1 has a hollow structure. That is, at least one space S is formed between the inner surface portion 7 b and the outer surface portion 7 a of the resin model 1. In the space portion molding step S13B, at least a space S is defined between the outer surface portion 7a and the inner surface portion 7b using a resin 3D additive manufacturing method.

  The hollow structure is preferably a structure in which a plurality of spaces S are regularly arranged three-dimensionally. For example, the resin model 1 has a plurality of first wall portions 5, a plurality of second wall portions 6, and a plurality of third wall portions (not shown), and is formed by these wall portions 5 and 6. A plurality of spaces S may be provided.

  The first wall portion 5 is disposed at a predetermined interval in the first direction. The 2nd wall part 6 is arrange | positioned at predetermined intervals in the 2nd direction orthogonal to a 1st direction. The third wall portion is disposed at a predetermined interval in a third direction orthogonal to the first direction and the second direction. By arranging the space S by such a method, the resin model 1 can be a lattice-shaped (mesh-shaped) hollow structure. That is, a structure in which at least a part of the space S is arranged in a lattice shape can be used.

  The configuration of the space S formed inside the resin model 1 is not limited to this, and may be a configuration in which one space S is provided without providing a wall portion. The space S may be defined only by the first wall portion 5. A plurality of spaces S may be formed by a honeycomb structure. Further, the cross-sectional shape of the space S may be a rectangle or a rhombus.

  The resin is, for example, a resin such as a urethane resin or an epoxy resin, and a resin having a melting point of 190 ° C. or higher. These resins are not limited to the above examples, and any resin may be used as long as it has strength up to about 190 ° C. and has elasticity.

As shown in FIG. 3, in the core-integrated mold making step S <b> 14, the resin model 1 is arranged at a predetermined position of the mold 8. Next, a slurry molded body is formed by injection molding, casting molding, or gel cast molding.
In the core-integrated mold making step S14, the slurry SL may be injected in a plurality of stages. Specifically, the core-integrated mold making step S14 includes a first injection step of injecting the slurry SL, a second injection step of injecting the slurry SL after a predetermined time after the first injection step, including. Note that it is not always necessary to inject the slurry SL in a plurality of stages.
As a result, the slurry SL is supplied to the cavity V2 of the mold 8 (between the mold 8 and the resin model 1) and the cavity V of the resin model 1.

When the slurry SL is supplied and a predetermined time elapses, the curing of the slurry SL is completed, and a molded body (core 3 and mold structure 11) of the slurry SL is obtained.
Next, the water in the silica is evaporated to dry the molded body of the slurry SL. As a drying method, for example, a method of introducing a molded body into a predetermined moisture drying furnace can be employed.
The drying method is not limited to the method described above, and for example, a hot air drying method in which hot air generated by a gas burner is introduced for drying or a natural drying method in which the air is left at room temperature may be employed.

  Thereby, the core 3 as shown in FIG. 4, the core 3 is covered from the outside, the resin model 1 having the same outer surface as the outer surface of the casting, which is a product, and the same material as the core 3, A core resin model integrated mold 12 having a mold structure 11 connected to the core 3 and covering the resin model 1 from the outside is formed.

The core / mold integrated firing step S15 is a step in which the core resin model integrated mold 12 is heated and fired. In the core / mold integrated baking step S15, for example, the core resin model integrated mold 12 is heated to, for example, about 900 ° C. in a baking furnace. Thereby, the water component and unnecessary component contained in the mold structure 11 are removed. Furthermore, the mold structure 11 is cured by firing.
The resin model 1 is melted by heat in the core / mold integrated firing step S15. That is, when the atmospheric temperature is equal to or higher than the melting point of the resin, the resin melts and disappears. As a result, the core-integrated mold 21 including the core 3 and the mold structure 11 as shown in FIG. 5 and formed of ceramics is completed.

Next, a casting manufacturing method in which precision casting is performed using a mold manufactured by the mold manufacturing method will be described.
As shown in FIG. 6, the casting manufacturing method includes a casting step S21 for pouring the core-integrated mold 21 and a core-integrated mold removing step S22 for removing the core-integrated mold 21. ing.
The casting step S21 is a step of pouring the core-integrated mold 21 after preheating the core-integrated mold 21 manufactured by the core-integrated mold manufacturing method (for example, 800 ° C. to 900 ° C.). is there. In the casting step S <b> 21, a molten casting material (for example, steel) is injected between the mold structure 11 and the core 3 through the opening of the core-integrated mold 21.

  The core-integrated mold removing step S22 is a process of removing the core-integrated mold 21 after the casting material injected in the casting step S21 is solidified. When the casting raw material is solidified into a casting in the core-integrated mold 21, the core-integrated mold 21 is eluted and removed. In the core-integrated mold removing step S22, for example, the core-integrated mold 21 is placed inside the autoclave, and the core-integrated mold 21 is eluted by repeating pressurization and decompression in a high-temperature alkaline solution.

  When the core-integrated mold removing step S22 is performed, finishing and heat treatment are performed, and a casting is completed through dimensional inspection, X-ray inspection, and the like.

  According to the above embodiment, by integrally forming the core 3 and the mold structure 11 with the same material, the difference in linear expansion coefficient between the core 3 and the mold structure 11 is eliminated. Thereby, the clearance between the core 3 and the mold structure 11 set by the difference in the linear expansion coefficient between the core 3 and the mold structure 11 can be reduced, and the casting can be thinned. Become.

  In addition, the manufacturing process can be shortened. Further, by forming the product part using the resin 3D additive manufacturing method, the internal cooling structure can be complicated and miniaturized, and the cooling efficiency of the turbine blade can be improved.

  Further, by using the gel cast molding method in the core-integrated mold making step S14, a monomer network undergoes radical polymerization (gel curing) in the mold, thereby forming a polymer network in the dispersion medium. can get. In this method, the flow process and the solidification process of the slurry SL are completely separated and the particles are fixed in place, so that the slurry properties are reflected as they are, and nonuniformity and defects in the molded body are less likely to occur.

  Further, in the core-integrated mold making step S14, the slurry SL can be injected in a plurality of stages to improve the filling property of the slurry SL.

[Second Embodiment]
Hereinafter, the core integrated mold manufacturing method of the second embodiment of the present invention will be described in detail with reference to the drawings. In the present embodiment, differences from the first embodiment described above will be mainly described, and description of similar parts will be omitted.
As shown in FIG. 7, in the core-integrated mold manufacturing method of the present embodiment, the fixing member 13 is embedded in advance between the resin model 1 and the mold 8 in the core-integrated mold forming step S <b> 14. It is characterized by. A green body (core material) may be used as the fixing member 13. The green body is obtained by injection molding slurry SL for forming a mold, and is an unsintered member.

  According to the above-described embodiment, the fixing member 13 is embedded in a part between the resin model 1 and the mold 8 in advance, so that the displacement of the resin model 1 can be prevented during injection molding.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like within a scope not departing from the gist of the present invention. .
In the above embodiment, the turbine rotor blade is described as an example of the casting, but the present invention is not limited to this. The resin-integrated core manufacturing method, mold manufacturing method, and resin-integrated core of the present invention can be applied to other precision castings.

Further, as shown in FIG. 8, the slurry SL supply ports 14 may be provided at a plurality of locations. Thus, by providing the slurry SL supply ports 14 at a plurality of locations, the slurry SL can be reliably supplied even if the casting has a complicated structure.
Further, as shown in FIG. 9, the slurry SL supply port 14 </ b> B may be provided at the lowermost portion of the mold 8, which is close to the connecting portion between the mold structure 11 and the core 3. In this way, the slurry SL can be sufficiently supplied also to the core 3 by providing the slurry SL supply port 14 </ b> B at the lowermost part of the mold 8.

Further, as shown in FIG. 9, a bolt B may be used as an alternative to the fixing member 13. The fixing position with the bolt B is preferably a position where a resin surface such as a gate is open.
By using the bolt B as the fixing member 13, the resin model 1 can be fixed using general-purpose parts. Further, the position of the bolt B can be easily adjusted.

DESCRIPTION OF SYMBOLS 1 Resin model 3 Core 5 1st wall part 6 2nd wall part 7a Outer surface part 7b Inner surface part 8 Mold 10 Sprue 11 Mold structure 12 Core resin model integrated mold 13 Fixing member 21 Core integrated mold B Bolt S space V1 cavity V2 cavity

Claims (13)

Mold,
Slurry that becomes ceramics is injected by solidifying between a resin model that has an outer surface part that forms the outer surface of the same shape as the outer surface of the casting that is the product, and an inner surface part that is a molding surface that forms the core. A core-integrated mold making step for forming a core-integrated mold comprising the core and the mold structure;
A core-integrated mold manufacturing method comprising: a mold baking process for heating and baking the core and the mold structure and removing the resin model.   The core-integrated mold manufacturing method according to claim 1, wherein the resin model has a plurality of spaces defined between the outer surface portion and the inner surface portion.   The core-integrated mold manufacturing method according to claim 2, wherein at least a part of the plurality of spaces is arranged in a lattice pattern.   The core resin mold manufacturing method according to any one of claims 1 to 3, wherein the resin model is formed of a resin having a melting point of 190 ° C or higher.   The core-integrated mold manufacturing method according to any one of claims 1 to 4, wherein the resin model is made of a 3D additive manufacturing material. The core-integrated mold making process includes:
A first injection step of injecting the slurry;
The core-integrated mold manufacturing method according to any one of claims 1 to 5, further comprising a second injection step of injecting the slurry after a predetermined time has elapsed after the first injection step.   The inside according to any one of claims 1 to 6, wherein a fixing member that holds the position of the mold is disposed between the resin model and the mold in the core-integrated mold making process. Child integrated mold manufacturing method.   The core-integrated mold manufacturing method according to claim 7, wherein the fixing member is a green body.   The core-integrated mold manufacturing method according to claim 7, wherein the fixing member is a bolt.   A casting manufacturing method for precisely casting a casting using the core-integrated mold manufactured by the core-integrating mold manufacturing method according to any one of claims 1 to 9. With the core
A core-integrated mold having a mold structure made of the same material as the core and connected to the core.   The core-integrated mold according to claim 11, wherein the material is a ceramic obtained by solidifying a slurry containing 60 mass% or more of silica.   The core-integrated mold according to claim 12, wherein the slurry contains an inorganic binder.

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