JP2007007663A - Lost wax pattern arranging ceramic core for casting, and method for producing casting using that - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new lost wax pattern for casting with which an inner barrel part, an outer barrel part and ribs are integrally formed, and a method for producing the casting with which an accurate gap between the inner barrel part and the outer barrel part can precisely be formed by using the lost wax pattern. <P>SOLUTION: This lost wax pattern for casting, is integrally formed with the wax to the almost cylindrical inner barrel part, the almost cylindrical outer barrel part inserting the one side end of the inner barrel part and the plurality of ribs connecting the outer barrel part with the inner barrel part, and ceramic cores are arranged as casting cores having the shape corresponding to the gap part between the ribs and the divided shape in the peripheral direction at the position formed between the adjacent ribs and corresponding to the gap part between the ribs penetrated along the axial direction of the inner barrel part. Further, the method for producing the casting, is integrally cast and formed of the inner barrel part, the outer barrel part and the ribs using the ceramic cores. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a casting disappearance model used for casting and a method for producing a casting using the casting disappearance model. In particular, the present invention relates to a casting disappearance model for casting such as a swirler for a gas turbine combustor which is used in a gas turbine combustor and is cast, and a casting manufacturing method using the casting disappearance model.

  For example, in a power generation gas turbine, high-pressure combustion gas for rotating gas turbine blades at high speed is generated by a gas turbine combustor. In this gas turbine combustor, a mixture of gas turbine fuel and air (hereinafter referred to as air mixed fuel) is combusted. At this time, an apparatus for efficiently mixing the gas turbine fuel and air is a gas turbine. It is a swirler for a combustor. A swirler for a gas turbine combustor generally includes an inner cylinder having a fixed portion of an injection nozzle for gas turbine fuel, and a gas turbine fuel which is provided in the inner cylinder and converts the intake and highly compressed air into a swirl flow. The fixed wing to be mixed and a cylindrical outer body that leads this air-mixed fuel further downstream. The inner cylinder and the outer cylinder are integrated so as to form a narrow gap, and the secondary air is introduced from the formed gap so that the air-mixed fuel is efficiently burned.

  In the swirler for the gas turbine combustor having the above-described configuration, the integration of the inner cylinder and the outer cylinder which needs to form a narrow gap is performed by welding or brazing at a plurality of ribs for connecting the inner cylinder and the outer cylinder. Etc., and were integrated by joining and fixing.

  On the other hand, there is also a proposal of applying a precision casting method to a complicated shape such as a combustor. For example, Patent Document 1 proposes a method in which a lost wax casting method is applied and an inner cylinder, an outer cylinder, and a rib that integrates them while forming a gap are simultaneously formed as combustor components. . In patent document 1, there exists the characteristic in formation of the vanishing model for shape | molding the casting_mold | template used for casting. Specifically, a first wax mold for forming the inner cylinder, a second wax mold for forming the outer cylinder, a plurality of ribs connecting the inner cylinder and the outer cylinder, and a gap serving as a gap A cylindrical ceramic mold for forming the void is separately prepared. A cylindrical ceramic mold is inserted between the first wax mold and the second wax mold, and a part of the first wax mold is coaxially inserted inside the hollow portion of the second wax mold. It is constructed by assembling.

  The method of providing the evaporative model with this cylindrical ceramic mold as a core is that refractory slurry and refractory particles infiltrate into the gaps between the ribs, which are narrow gaps that serve as the secondary air inlets described above. It is excellent in that it enables molding of a precise mold.

JP 2004-25239 A

This inventor examined applying the cylindrical ceramic type | mold in patent document 1 for manufacture of the swirler for gas turbine combustors.
The inter-rib gap that forms the gap between the inner cylinder and the outer cylinder of the swirler for the gas turbine combustor is formed by the thickness of the cylindrical portion of the cylindrical ceramic mold. The cylindrical ceramic mold is formed by injecting or pouring a ceramic raw material into a mold having a cavity corresponding to the cylindrical ceramic mold, and then sintering the green body taken out from the mold. It was thought that it can be manufactured by becoming.

  Here, the first problem is that the thickness of the cylindrical portion of the cylindrical ceramic type must be extremely thin in order to make the gap between the ribs narrow. For example, Patent Document 1 discloses a configuration example in which the thickness of a cylindrical portion of a cylindrical ceramic type is about 0.5 to 5 mm. However, in manufacturing a cylindrical ceramic mold having a very thin cylindrical portion, formation of a mold cavity for molding the mold, formation of a green body using the mold, and sintering of the green body, etc. There are many technical problems in each of these processes. For example, non-rotation of the ceramic raw material to the thin cylindrical portion, insufficient packing density, self-weight deformation due to the thin and integral cylindrical shape, non-uniform shrinkage during sintering, cracking and breakage, and the like.

  Further, in the cylindrical ceramic mold disclosed in Patent Document 1, it is necessary to form through holes in the ribs, which is a factor that makes manufacture difficult. In other words, the plurality of ribs for connecting the inner cylinder and the outer cylinder must be formed by providing a plurality of through-holes penetrating from the inside to the outside in the thin cylindrical portion of the cylindrical ceramic type. Don't be. Since this through hole is provided, it is difficult to open the mold along the central axis direction of the cylindrical portion in the mold opening after the injection molding of the ceramic raw material. For this reason, a configuration is adopted in which a cavity for forming a cylindrical ceramic mold is formed by combining a plurality of slide molds radially movable in the radial direction inside or outside the cylindrical portion. It will be. In the case of this configuration, the structure of each slide mold and its movable mechanism is complicated, and in order to obtain a cavity in which the thickness of the cylindrical portion can be formed extremely thin and stably, the mold of each slide mold The positioning at the time of tightening is required to have extremely high accuracy. Furthermore, in the parting line which is a joint between the slide molds combined by clamping, there is a disadvantage that wear and insertion are likely to occur when the ceramic raw material is injected or poured.

  An object of the present invention is to solve the above-mentioned problems, and to provide a novel casting vanishing model in which an inner cylinder, an outer cylinder, and a rib are integrally formed, and a precise gap between the inner cylinder and the outer cylinder. The object is to provide a precision casting method of a casting that can be formed with high accuracy.

  The present inventor examined the inter-rib gaps, which are narrow gaps connecting the inner cylinder and the outer trunk, the means for forming each rib, and the integral molding of the vanishing model for casting. The castability model for casting is integrated by arranging the ceramic cores, which are the shapes corresponding to the gaps between the ribs and are divided in the circumferential direction, in substantially cylindrical shapes at corresponding locations. The present inventors have found that the above-mentioned problems can be solved by forming and casting using a vanishing model for casting in which the ceramic core is disposed, and have arrived at the present invention.

  That is, the vanishing model for casting having the ceramic core of the present invention comprises a substantially cylindrical inner cylinder, a substantially cylindrical outer cylinder that inserts one end of the inner cylinder, the outer cylinder, and the inner cylinder. A plurality of ribs to be connected are integrally formed of wax, and the ribs are provided at locations corresponding to gaps between the ribs penetrating along the axial direction of the inner cylinder formed between the adjacent ribs. It is a vanishing model for casting in which a ceramic core in which a ceramic core serving as a casting core having a shape corresponding to an interspace is divided in the circumferential direction is arranged.

By using the castability model for casting in which the above-described ceramic core is disposed, a new casting in which the inner cylinder, the outer cylinder, and the rib are integrally cast can be obtained. That is, the casting manufacturing method of the present invention includes a substantially cylindrical inner cylinder, a substantially cylindrical outer cylinder that inserts one end of the inner cylinder, and a plurality of ribs that connect the outer cylinder and the inner cylinder. And a gap between the ribs extending along the axial direction of the inner cylinder formed between the adjacent ribs, and the inner cylinder, the outer cylinder, and the rib are integrally cast. A manufacturing method of
(1) A step of forming a vanishing model for casting having substantially the same shape as the casting,
(2) A mold forming step for removing the casting disappearance model after coating the disappearance model for casting with a refractory;
(3) a casting process for casting into the mold;
The gaps between the ribs have shapes corresponding to the gaps between the ribs and are divided in the circumferential direction, and ceramic cores serving as casting cores are arranged in a substantially cylindrical shape, respectively. It is a manufacturing method of the casting obtained by the vanishing model for casting.

  In the present invention, it is preferable that ribs are formed by gaps formed by end faces of adjacent ceramic cores. Moreover, it is preferable to provide the ceramic core with a locking portion that locks the mold. Moreover, it is preferable to elute and remove the ceramic core with an alkaline solution after the casting step.

  The castability model for casting in which the ceramic core of the present invention is disposed is a castability model for casting seamlessly formed by wax at the portions corresponding to the inner trunk, the outer trunk, and the ribs, It does not have a dent-like defect caused by the assembly of the cast-off vanishing model. Then, according to the casting manufacturing method of the present invention using this vanishing model for casting, a precise gap between the inner cylinder and the outer cylinder is accurately formed, and the inner cylinder, the outer cylinder, and the rib are integrally cast. A molded new casting can be obtained, which is an extremely effective technology in industry.

  An important feature of the castability model for casting in which the ceramic core of the present invention is disposed is a casting having a shape corresponding to the gap between ribs and a shape divided in the circumferential direction at a position corresponding to the gap between ribs. That is, the ceramic cores serving as cores are arranged in a substantially cylindrical shape. By using ceramic cores as the casting cores that have a shape divided in the circumferential direction, each ceramic core is in the form of a thin plate, so the self-weight deformation and non-uniform shrinkage during sintering are extremely small, and dimensional accuracy A good ceramic core can be obtained. As a result, the problem of filling density, the problem of dimensional accuracy, or the problem of complicated operation of the mold at the time of manufacturing the cylindrical ceramic mold, which has been a problem with the conventional cylindrical ceramic mold, can be solved.

  In addition, ribs are formed by the gaps formed by the end faces of adjacent ceramic cores, eliminating the need to form through holes in the ceramic cores, simplifying the shape, and increasing the accuracy of the core. Is possible. Furthermore, by forming the gaps between the ribs and the ribs with the same shape of the ceramic core, it is possible to improve the positioning accuracy in which the ceramic cores serving as the casting cores are arranged in a substantially cylindrical shape. It is suitable for improving production efficiency.

  An important feature of the casting manufacturing method of the present invention is that the casting is integrally cast using a casting vanishing model having a seamless ceramic core having substantially the same shape as the casting. As a result, there is no dent-like casting defect due to the welded or brazed part or the seam of the vanishing model for casting, and mechanical strength, reliability, and heat resistance are dramatically improved compared to the conventional case. A new casting can be obtained.

  In the present invention, a fixed wing or the like can be integrally formed with the inner cylinder by wax in the hollow portion of the inner cylinder of the casting vanishing model in which the ceramic core is disposed. Accordingly, a substantially cylindrical inner cylinder, a fixed wing formed in a hollow portion of the inner cylinder, a substantially cylindrical outer cylinder for inserting one end of the inner cylinder, and a plurality of connecting the outer cylinder and the inner cylinder. The ribs are integrally formed of wax, and the portions corresponding to the inter-rib gaps extending along the axial direction of the inner cylinder formed between the adjacent ribs correspond to the inter-rib gaps. It is possible to obtain a vanishing model for casting in which a ceramic core serving as a casting core having a shape and a shape divided in the circumferential direction is arranged. Moreover, by using this, a substantially cylindrical inner cylinder, a fixed wing formed in a hollow portion of the inner cylinder, a substantially cylindrical outer cylinder that inserts one end of the inner cylinder, an outer cylinder, and an inner cylinder A plurality of ribs that connect to each other, and an inter-rib gap that extends along the axial direction of the inner cylinder formed between adjacent ribs, and the inner cylinder, the fixed wing, the outer cylinder, and the ribs are integrated. A casting formed by casting can be obtained.

Hereinafter, the casting disappearance model in which the ceramic core according to the present invention is arranged and the method for producing a casting using the same will be described in detail with reference to the drawings.
For example, as a casting, a swirler part for gas turbine combustor (hereinafter referred to as a swirler part) is taken as an example, and a typical shape thereof is shown in FIG. In FIG. 5, the swirler component 1 includes a substantially cylindrical inner cylinder 2 and a substantially cylindrical outer cylinder 4. The inner cylinder 2 has a fixed blade (not shown) for converting highly compressed air into a swirling flow and taking it into the inner cylinder 2, and a nozzle fixing part for fixing a gas turbine fuel injection nozzle. (Not shown) may be provided integrally with the inner cylinder 2 or by assembly.

  The outer cylinder 4 is inserted into one end of the inner cylinder 2 and fixed to the inner cylinder 2 by a plurality of ribs 5. Further, a space between adjacent ribs 5 is a narrow gap that penetrates between the outer peripheral side of the inner cylinder 2 and the inner peripheral side of the outer cylinder 4, and efficiently burns the air-mixed combustion sent from the inner cylinder 2. The inter-rib gap 6 serving as a secondary air inlet for the purpose is formed in each.

An example of the manufacturing method of the present invention in which the swirler component 1 shown in FIG. 5 is integrally cast will be described below in detail according to the required steps.
(1) Molding process of vanishable model In the manufacturing method of the casting of this invention, the molding process of a vanishing model becomes the most important process. As an example, a ceramic core corresponding to the gap between the ribs, a solvent-soluble wax or a metal-made placing core corresponding to the hollow part of the inner and outer cylinders are arranged in the mold, and the mold is clamped. Later, a wax that is a disappearing material is injection-molded into the mold, and the resulting molded product is taken out of the mold and the above-mentioned solvent-soluble wax or metal-made placing core is removed to release the mold. A process for obtaining a casting vanishing model in which a ceramic core is disposed at a position corresponding to the gap will be described below.

First, a configuration example in a mold for forming a cavity corresponding to a castability model for casting in which a ceramic core having substantially the same shape as the swirler component 1 is arranged will be described.
As shown in FIG. 2, a mold configuration in which the middle molds 12 and 13 are combined with the upper mold 11 and the lower mold 14 is preferable. Even if the outer peripheral surface of the swirler component 1 has an undercut, this mold configuration divides the middle dies 12 and 13 in the circumferential direction of the swirler component 1 and divides the middle dies 12 and 13 into the swirlers. By configuring each component 1 to be openable and closable in the radial direction with respect to the central axis, the mold can be easily opened. For example, the middle die 12 may be divided into a plurality of pieces in the circumferential direction of the swirler component 1 when the inner die 2 has an undercut on the outer circumferential surface, and the middle die 13 may be divided in the circumferential direction of the swirler component 1. In addition, when it does not have an undercut in the outer peripheral surface of the outer cylinder 4, the middle mold | type 13 and the lower mold | type 14 can also be comprised integrally.

  And in the metal mold | die comprised as mentioned above, the cores 15 and 16 are positioned and arrange | positioned with respect to the lower mold | type 14 and the intermediate mold 13, Furthermore, the core 17 is positioned and arrange | positioned with respect to the core 16. FIG. Dividing the cores 16 and 17 is preferable because it facilitates the positioning and positioning of the core 15 regardless of the presence or absence of the undercut in the hollow portion of the inner body 2. The cores 15 and 16 may be integrally formed cores, but by dividing the cores 15 and 16, the core 16 can be a reusable placement core made of a metal material or the like. It is advantageous to reduce the manufacturing cost. A placing core can also be used for the core 17. Further, in the case of a placement core, a placement core made of, for example, a metal material or ceramic can be used.

  Next, each portion corresponding to the inter-rib gap 6 is made of a ceramic raw material so as to be engaged with the middle mold 13 and the core 15 and has a shape corresponding to the inter-rib gap 6 and divided in the circumferential direction. Ceramic cores 10 serving as casting cores having the above-described shapes are arranged in a substantially cylindrical shape.

  Positioning and fixing of the ceramic cores 10 arranged in the mold are important. As a means for that purpose, for example, recesses 21a and 22a serving as clues for the middle mold 13 and the core 15 are provided. Convex locking portions 21b and 22b corresponding to the concave portions 21a and 22a are provided. And there exists a means to position and fix the ceramic core 10 by fitting these latching | locking parts 21b and 22b and recessed part 21a and 22a. This means is preferable because the ceramic core 10 does not move even when a disappearable material is injected or poured into the mold, and a disappearable model with good dimensional accuracy is obtained.

  Further, as another means, for example, as shown in FIG. 3, a contact portion 10 a that can contact an adjacent ceramic core 10 is provided on a part of the end surface of the ceramic core 10, and the ceramic cores 10 are brought into contact with each other. The middle mold 13 is arranged so as to be sandwiched between the middle mold 12 and the core 15. With this configuration, adjacent ceramic cores 10 are engaged with each other, and all ceramic cores 10 arranged in a substantially cylindrical shape are integrally engaged and positioned and fixed. Thus, by providing the contact part 10a which makes a part of end surface of the adjacent ceramic core 10 contact, it becomes substantially cylindrical shape, positioning each ceramic core 10 accurately, without providing the special positioning and fixing means. This is preferable because it can be arranged. Moreover, it becomes possible to use the ceramic core 10 having the same shape, and the production efficiency of the ceramic core 10 and the swirler component 1 can be significantly improved.

  As described above, after the ceramic core 10 and the cores 15, 16, and 17 are arranged, the upper mold 11, the middle molds 12, 13, and the lower mold 14 are clamped, whereby the inner cylinder 2 and the outer cylinder 4 of the swirler component 1. The inner cylinder corresponding cavity 20a, the outer cylinder corresponding cavity 20b, and the rib corresponding cavity 20c corresponding to each of the ribs 5 can be formed in the mold.

  Next, a model in which the ceramic core 10 and the cores 15, 16, and 17 are disposed by injecting wax, which is a molten or semi-molten, disappearing material, into the cavity in the above-described mold (hereinafter, intermediate) A model). Then, the mold is opened and the molded intermediate model is taken out, and the cores 15, 16, and 17 are removed from the intermediate model, thereby having substantially the same shape as the swirler component 1, and the gap between the ribs. A vanishing model for casting in which the ceramic core 10 is disposed at a position corresponding to the portion 6 can be formed.

  The core 15 to be arranged in the intermediate model is preferably a core 15 made of solvent-soluble wax, so that the core 15 can be easily eluted and removed from the intermediate model by a simple means of immersing the intermediate model in the solvent. Can be made. As the solvent, water that does not easily react with the ceramic core 10 or an acidic aqueous solution such as 5% hydrochloric acid is suitable. As the wax, a wax that is soluble in water or an acidic aqueous solution as a solvent may be used. More preferably, water that is easy to handle is used as a solvent, and a water-soluble wax is used.

  By the procedure described above, a casting disappearance model 1 'as shown in FIG. 1 can be obtained as an example. In other words, the castable model 1 ′ for casting has a substantially cylindrical inner cylinder 2 ′, a substantially cylindrical outer cylinder 4 ′ in which one end of the inner cylinder 2 ′ is inserted, an outer cylinder 4 ′ and an inner cylinder 2. A plurality of ribs 5 ′ that are connected to each other are formed integrally with wax, and are formed in inter-rib gap portions 6 that penetrate along the axial direction of the inner cylinder 2 ′ formed between adjacent ribs 5 ′. In a corresponding place, there is a disappearing model 1 ′ for casting in which a ceramic core 10 serving as a casting core having a shape corresponding to the gap 6 between the ribs and divided in the circumferential direction is arranged.

(2) Mold Forming Process The mold forming process in the casting manufacturing method of the present invention is a mold for the casting vanishable model obtained by the casting vanishable model forming process in which the ceramic core is disposed. A mold with a cavity having substantially the same spatial shape as the casting is prepared by coating a refractory and coating it with a refractory and removing the wax, which is a vanishing material, from the vanishing model for casting after coating. It is a process of forming.

  For example, first, a feeder, a runner, or the like made of a disappearable material similar to that of the casting disappearance model is bonded to the casting disappearance model to form a tree shape. A casting refractory model having a tree shape is coated with a refractory to have a predetermined mold thickness. The refractory coating is preferable because it is effective for improving the strength of the mold and preventing molten metal leakage during casting by forming a plurality of refractory layers by repeating a plurality of times. As the refractory material to be coated, zircon, alumina, mullite, etc., which can withstand the molten metal cast in the casting process, can be used. It is also preferable to assemble a plurality of castability models for casting into a single tree and coat the plurality of castability models simultaneously with a refractory because the production efficiency is improved.

  Next, after the mold molded as described above is sufficiently dried, the wax which is the vanishing material of the casting vanishing model is removed from the mold. As a means for removing the vanishing material, for example, there is a means for removing it by heating and melting with a high temperature steam autoclave or the like. As a result, it is possible to obtain a casting mold having substantially the same shape as the casting and having the ceramic core disposed at a position corresponding to the gap between the ribs. More preferably, sufficient strength is imparted to the mold by baking the obtained mold at a high temperature of, for example, 1000 ° C. or higher.

(3) Casting process The casting process in the casting manufacturing method of the present invention is performed by casting a molten metal obtained by melting a metal material into a mold and cooling the mold obtained by the mold molding process described above. This is a step of obtaining an integrally cast casting having substantially the same shape as that of the above-described casting vanishing model by removing the mold and removing the remaining ceramic core.

  When the casting of the present invention is applied to, for example, a swirler part for a gas turbine combustor that requires high temperature strength and corrosion resistance as a combustion part, the metal material used for this is, for example, austenitic stainless steel such as SCS13 or SUS304, Various heat-resistant steels and heat-resistant alloys, Ni-based and Co-based super heat-resistant alloys, and the like are suitable. And in the manufacturing method of the casting of this invention, the above-mentioned metal material is melt | dissolved in the air suitable for the characteristic in the inert gas or a vacuum in a vacuum, and this molten metal is supplied to a casting_mold | template.

  Casting to the mold can be performed under reduced pressure, suction or vacuum in consideration of various conditions such as the characteristics of the molten metal and the amount of hot water in the mold. Preferably, it is suction casting, and this improves the hot water performance, and for example, even a casting having a thin inner cylinder 2 and an outer cylinder 4 like the swirler component 1 can be surely filled with molten metal. . Then, after casting, the mold is removed after cooling, and unnecessary runners and hot water are removed from the cast product. Further, in order to remove mold scraps, scales and the like adhering to the cast product, it is also preferable to perform shot blasting, sand blasting or the like on the cast product. Next, by removing the ceramic core remaining in the casting, it is possible to obtain a casting in which the inner cylinder, the outer cylinder, and the rib are integrally formed. Further, machining or the like can be further performed as necessary.

Means for removing the ceramic core from the casting include mechanical vibration, ultrasonic crushing and crushing, and solvent elution. Preferably, the ceramic core is surely dissolved and removed by a simple means of immersing the ceramic core in a solvent and eluting it. For example, the solvent can be an alkaline solution, and the ceramic core can be formed of a SiO ₂ refractory that can be easily removed by an alkaline solution. Further, in order to facilitate to more elution, the content of SiO ₂ is to 50% by weight or more. Further, such ZrSiO _{4, Al} 2 _{O 3,} or _the may be mixed. And, as the above-mentioned alkaline solution, a potassium hydroxide aqueous solution, a sodium hydroxide aqueous solution having a concentration of about 30%, or a mixed aqueous solution is used, and the temperature of the aqueous solution is about 100 to 150 ° C., so that handling is easy. And elution efficiency is also improved. In addition, although acidic solutions, such as a boiling acid, can also be used as a solvent, the point which is easy to react with the metal material used as casting is disadvantageous.

It is a schematic diagram which shows the specific example of the vanishing model for casting of this invention. It is a schematic diagram which shows the example of a metal mold | die structure in the manufacturing method of the casting of this invention. It is a schematic diagram which shows the example of an arrangement | sequence of the ceramic core in this invention. It is a schematic diagram which shows the specific example of the ceramic core in this invention. It is a schematic diagram which shows the specific example of the casting in this invention.

Explanation of symbols

  1. Swirler parts, 1 '. Casting vanishing model, 2, 2 '. Inner trunk 4, 4 '. Outer trunk, 5, 5 '. Ribs, 6; 9. Inter-rib gap Ceramic core, 10a. 10. contact portion; Upper mold, 12, 13. Medium size, 14. Lower mold, 15, 16, 17. Naka, 20a. Cavity corresponding to the inner cylinder, 20b. Outer cylinder-compatible cavity, 20c. Ribs corresponding cavities, 21a, 22a. Recesses, 21b, 22b. Locking part

Claims (5)

  A substantially cylindrical inner cylinder, a substantially cylindrical outer cylinder that inserts one end of the inner cylinder, and a plurality of ribs that connect the outer cylinder and the inner cylinder are integrally formed of wax. The portion corresponding to the gap between the ribs penetrating along the axial direction of the inner cylinder formed between the adjacent ribs has a shape corresponding to the gap between the ribs and divided in the circumferential direction. A vanishing model for casting having a ceramic core arranged therein, wherein a ceramic core serving as a casting core having a shape is arranged. A substantially cylindrical inner cylinder, a substantially cylindrical outer cylinder for inserting one end of the inner cylinder, a plurality of ribs connecting the outer cylinder and the inner cylinder, and the adjacent ribs are formed. A method for producing a casting comprising an inter-rib gap portion penetrating along an axial direction of the inner cylinder, wherein the inner cylinder, the outer cylinder, and the rib are integrally cast;
(1) A step of forming a vanishing model for casting having substantially the same shape as the casting,
(2) A mold forming step for removing the casting disappearance model after coating the disappearance model for casting with a refractory;
(3) a casting process for casting into the mold;
The gaps between the ribs have shapes corresponding to the gaps between the ribs and are divided in the circumferential direction, and ceramic cores serving as casting cores are arranged in a substantially cylindrical shape, respectively. A method for producing a casting, characterized in that it is obtained by a vanishing model for casting.   The method for manufacturing a casting according to claim 2, wherein the rib is formed by a gap formed by end faces of adjacent ceramic cores.   The said ceramic core comprises the latching | locking part latched to the said casting_mold | template, The manufacturing method of the casting in any one of Claim 2 or Claim 3 characterized by the above-mentioned.   The method for producing a casting according to any one of claims 2 to 4, wherein the ceramic core is eluted and removed by an alkaline solution after the casting step.

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