JPH0441203A - Manufacture of ceramic casting molded form - Google Patents

Abstract

PURPOSE:To prevent the cracking due to shrinkage by forming a non-adsorptive material layer having non-adsorptivity to ceramics in a sludge-shaped raw material on the inner surface of a matrix, casting the sludge-shaped raw material into the matrix and forming a hole to a section corresponding to the non-adsorptive material layer. CONSTITUTION:A matrix 5, on an inner surface 5a of which a non-adsorptive material layer 7 is shaped, is held from upper and lower sections by a molding jig 9 with a sludge-shaped raw material flow path 9a and a molding jig 10, from which a projecting section 10a is projected. A sludge-shaped raw material 11 is casted into the matrix 5 from the sludge-shaped raw material flow path 9a. When the raw material 11 is left to stand, a ceramic-wall-shaped layer 12 is attached to the inner surface 5a of the matrix 5 and grown. Since ceramics are not attached to the non-adsorptive material layers 7, a hole 13 is formed to the ceramic wall-shaped layer 12. When the wall thickness of the ceramic wall-shaped layer 12 reaches a specified value, the sludge- shaped raw material 11 is discharged, and the ceramic wall-shaped layer 12 is dried together with the matrix 5. Since the hole 13 is formed to the ceramic wall-shaped layer 12, shrinkage stress is not generated in the ceramic wall-shaped layer12, thus generating no crack, then improving productivity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a ceramic casting body having holes.

[Prior art] A ceramic cast body is produced by pouring a slurry-like raw material made of ceramic powder and a solvent into a water-absorbing matrix to form a residual ceramic wall layer on the inner surface of the matrix. In the method for manufacturing a ceramic casting body that forms a ceramic casting body, a core has conventionally been used when manufacturing a ceramic casting body having holes. That is, a hole is previously formed in the mother mold, and a core is inserted into the hole in the mother mold before pouring the slurry raw material, so that the tip of the core protrudes from the inner surface of the mother mold.

[Problem to be solved by the invention] When the ceramic wall layer remaining on the inner surface of the mother mold reaches a predetermined thickness, the slurry-like raw material is drained from the inside of the mother mold, and the ceramic wall layer is removed from the mother mold. After drying together with the mold, the mother mold is removed to obtain a ceramic molded body. However, in the conventional method described above, the ceramic wall layer contracts during drying and shrinkage stress is generated on the core. Cracks may occur in the ceramic molded body before it is removed, and the cracked ceramic molded body must be discarded, resulting in poor productivity. In addition, since it is necessary to form holes in the mother mold in advance for inserting the core, multiple types of ceramic castings with the same overall shape but different numbers, positions, sizes, shapes, etc. of holes can be made. When manufacturing, it was necessary to create a master mold for each type.

[Means for Solving the Problems] In order to solve the above problems, the method for manufacturing a ceramic cast molded body of the present invention includes pouring a slurry-like raw material consisting of ceramic powder and a solvent into a mother mold having water absorption properties. In a method for manufacturing a ceramic casting body, which forms a ceramic casting body by heating hot water and forming a residual ceramic wall layer on the inner surface of the matrix, a slurry-like raw material is added to an arbitrary location on the inner surface of the matrix. By forming a non-adsorptive material layer that is non-adsorptive to the ceramic inside, and then pouring a slurry-like raw material into the inside of the matrix, holes are formed in the portions corresponding to the non-adsorptive material layer. A ceramic casting body is obtained.

[Operation] Since no ceramic wall layer remains in the area where the non-adsorptive material layer is formed, pores are formed in this area.

[Example 1] Hereinafter, an example of the present invention will be described based on FIGS. 1 to 8.

FIG. 1 is a cross-sectional view of a cast ceramic body manufactured by a manufacturing method according to an embodiment of the present invention, and the cast ceramic body 1 has a substantially cylindrical shape with a tapered lower half. . Holes 2.degree. 3 are formed at predetermined intervals in the circumferential direction at the upper and lower ends of the ceramic casting body 1. Note that the ceramic cast body 1 is used as an inner cylinder of a combustor of a ceramic gas turbine.

FIG. 2 is a front view of divided pieces of the mother mold used in the method for manufacturing a ceramic cast molded body according to an embodiment of the present invention, in which the divided pieces 6 constituting the mother mold 5 have a semi-cylindrical outer surface and an inner surface. The shape is such that the outer surface of the ceramic casting body 1 is divided into two along the axis.

That is, by using two divided pieces 6 as shown in FIG. 2 and bringing the mating surfaces 6a and 6b of the two divided pieces 6 into contact with each other, a cast body with a cylindrical outer surface and a ceramic cast body with an inner surface 5a is formed. A matrix 5 having the same shape as the outer surface of 1 is constructed. The matrix 5 is made of a water-absorbing material such as plaster, and the holes 2 and 3 of the ceramic casting body 1 are formed on the inner surface 5a of the matrix 5.
A non-adsorptive material layer 7 having substantially the same shape and dimensions as the hole 2.3 is formed at a position corresponding to the hole 2.3. The non-adsorptive material layer 7 is made of a material that is non-adsorptive to ceramics, such as Teflon, polyethylene, or polypropylene, and in this embodiment, the non-adsorptive material layer 7 has a thickness of about several tens of μm. As shown in FIG. 7, it is attached to the inner surface 5a of the matrix 5 using a Teflon adhesive sheet. Incidentally, pipes 8a and 8b having a large number of holes for supplying drying air are embedded in the divided piece 6.

When manufacturing the ceramic casting body 1, first the third
As shown in the figure, a molding jig 9 has a slurry-like raw material flow path 9a for pouring and draining the slurry-like raw material, and a protrusion 10a is provided to reduce the amount of pouring of the slurry-like raw material. A mold 5 having a non-adsorbent material layer 7 formed on its inner surface 5a is sandwiched between the molding jig 10 from above and below. Next, as shown in FIG. 4, a slurry raw material 11 is poured into the mother mold 5 from the slurry raw material flow path 9a of the molding jig 9. The slurry-like raw material 11 is a slurry-like mixture of ceramic powder and a solvent. If left in this state, the matrix 5 will appear as shown in Figure 5.
A ceramic wall-like layer 12 is deposited on the inner surface 5a and gradually grows. At this time, since the ceramic is not attached to the non-adsorptive material layer 7, holes 13 are formed in the ceramic wall layer 12 as shown in FIG. And as shown in Figure 6,
When the thickness of the ceramic wall layer 12 reaches a predetermined value, for example, about 5 mm, the slurry raw material 11 is removed from the inside of the matrix 5, and the ceramic wall layer 12 is dried together with the matrix 5. When the ceramic wall layer 12 is sufficiently dried, the master mold 5 is removed and the ceramic wall layer 12 is fired to obtain the ceramic cast body 1 as shown in FIG.

Note that the holes 13 of the ceramic wall layer 12 become the holes 2 and 3 of the ceramic casting body 1.

In this way, by forming the non-adsorptive material layer 7 on the inner surface 5a of the matrix 5, it is possible to prevent the ceramics in the slurry-like raw material 11 from attaching, and to form the holes 13 in the ceramic wall-like layer 12. When the ceramic wall layer 12 shrinks due to drying, it slides on the non-adsorbent material layer 7 or the non-adsorbent material layer 7 is deformed, so that no shrinkage stress is generated in the ceramic wall layer 12. Therefore, cracks due to shrinkage do not occur in the ceramic wall layer 12, and productivity can be improved. In addition, by peeling off the non-adsorbent material layer 7 formed on the inner surface 5a of the matrix 5 and forming a new non-adsorbent material layer 7, the overall shape is the same and the number, position and size of the holes 2.3 are different. Various ceramic casting bodies 1 having different shapes etc. can be manufactured using one mother mold. Furthermore, if the non-adsorptive material layer 7 is sufficiently thin compared to the wall thickness of the ceramic casting body 1 as in this embodiment, the peripheral wall of the hole 13 will be formed on the outer surface of the ceramic wall-like layer 12 as shown in FIG. Since it has an arcuate cross-section whose diameter gradually increases from the side toward the inner surface, it is very convenient when the obtained ceramic-socket cast molded body 1 is used as an inner cylinder of a gas turbine combustor. That is, during operation of the gas turbine, the temperature of the inner surface of the ceramic casting body 1 is higher than that of the outer surface, and therefore the inner surface has a larger thermal expansion than the outer surface. With such a shape, stress generated near the peripheral walls of the holes 2 and 3 due to thermal expansion can be reduced.

[Another Example] In the above example, an adhesive sheet was used as the non-adsorbent material layer 7, but the present invention is not limited to this. For example, paint may be applied to the inner surface 5a of the matrix 5. The non-adsorptive material layer 7 may also be formed thereby.

Further, as shown in FIG. 9 or 10, an annular protrusion 14a protrudes from the outer peripheral edge in the axial direction.

The height of the protrusions 14a, 15a is adjusted using the non-adsorbent material layer 14.
It is also possible to make the peripheral walls of the holes 2 and 3 of the obtained ceramic casting body 1 exactly cylindrical by making the wall thickness almost the same as that of the ceramic casting body 1 . In this way, the hole 2.3 with a small diameter can be formed with high precision.

Further, as shown in FIG. 11, a non-adsorbent material layer 16 whose outer peripheral surface is recessed with a semicircular cross section is used to obtain a ceramic casting body 1 in which the peripheral wall of the hole 2.3 protrudes with a semicircular cross section. You can.

Further, in the above embodiment, an example was explained in which a ceramic cast molded body 1 was manufactured to be used as an inner cylinder of a combustor of a gas turbine, but the present invention is not limited to this. It is possible to manufacture various ceramic/socket casting bodies, such as ceramic substrates used for mounting circuits, ceramic furnaces, etc. Also hole 2.3
The shape of the hole is not limited to a circular shape, and a hole of any shape can be formed.

[Effects of the Invention] As explained above, according to the present invention, a non-adsorptive material layer that is non-adsorptive to the ceramics in the slurry-like raw material is formed at any location on the inner surface of the matrix, and then By pouring a slurry-like raw material into the inside of the matrix, a ceramic cast molded body with holes in the portion corresponding to the non-adsorptive material layer is obtained, so a non-adsorptive material layer is formed on the inner surface of the matrix. By doing so, the ceramics in the slurry-like raw material are prevented from being attached and pores are formed in the ceramic wall layer, so that when the ceramic wall layer shrinks due to drying, it will slide on the non-adsorbent material layer or or as a result of deformation of the non-adsorbent material layer;
No shrinkage stress is generated in the ceramic wall layer.

Therefore, cracks due to shrinkage do not occur in the ceramic wall layer, and productivity can be improved. In addition, by peeling off the non-adsorptive material layer formed on the inner surface of the matrix and forming a new non-adsorptive material layer, various ceramics with the same overall shape but different numbers, positions, sizes, and shapes of holes can be created. A cast molded body can be manufactured using one mother mold.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a ceramic casting body manufactured by a method for manufacturing a ceramic casting body in an embodiment of the present invention, and FIG. 2 is a front view of a divided piece of a mother mold used in the same manufacturing method. Figures 3 to 6 are explanatory diagrams of the steps of the same manufacturing method, Figure 7 is an enlarged cross-sectional view of the non-adsorptive material layer formed on the inner surface of the matrix, and Figure 8 is an illustration of the grown ceramic wall layer. 9 to 11 are enlarged sectional views of a non-adsorptive material layer formed on the inner surface of a matrix in different embodiments. DESCRIPTION OF SYMBOLS 1... Ceramic cast molded body, 5... Mother mold, 7゜14.15.16... Non-adsorptive material layer, 11... Slime-like raw material, 12... Ceramic wall-like layer, 13...
Patent Applicant: Yanmar Diesel Co., Ltd.a Figure 1: AX body Figure 7: Figure S

Claims (1)

[Claims] 1. A ceramic cast molded body is formed by pouring a slurry-like raw material made of ceramic powder and a solvent into the inside of a water-absorbing matrix to form a residual ceramic wall layer on the inner surface of the matrix. In the method for manufacturing a ceramic cast molded body, a layer of a non-adsorptive material having non-adsorptive properties to the ceramics in the slurry-like raw material is formed at any location on the inner surface of the matrix, and then A method for producing a cast ceramic body, characterized in that a cast ceramic body having holes in a portion corresponding to the non-adsorptive material layer is obtained by pouring the slurry-like raw material into a mold.