JPH0822531B2 - Method for producing fiber-reinforced ceramic hollow molded article - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a fiber-reinforced ceramic hollow molded body.

[Prior Art] A conventional method for producing a fiber-reinforced ceramic hollow molded article is as follows. A porous mold having a core inside a molding space is pressed with a fluid formed by mixing a ceramic powder and a liquid into a fiber component. The liquid is removed from the fluid by pouring and absorbing the liquid in the fluid into the porous part of the porous mold or by passing the liquid from the porous part, and the ceramic powder and the fiber component are formed inside the molding space. The so-called sludge casting molding for forming a hollow molded body has been performed.

The hollow molded body thus molded is taken out from the porous mold, dried and sintered to obtain a fiber-reinforced ceramic hollow component.

[Problems to be Solved by the Invention] However, the conventional method for producing a fiber-reinforced ceramic hollow molded article has the following problems.

Since it is necessary to slowly inject the fluid into the molding space over time, the liquid is removed from the fluid injected into the molding space, and the ceramic powder and fiber components are first solidified during the process. There is a possibility that the density is not uniform between the part that is solidified in the hollow part and the part that is solidified later, and strain or voids may occur inside the hollow molded body.

In addition, the pressure injection pressure only at the time of mud casting,
Since a sufficient pressure cannot be applied to the molded body, the hollow molded body formed has a low density.

Moreover, the orientation of the fiber components in the hollow molded article cannot be adjusted only by the mud casting, and the fiber components are three-dimensionally and randomly oriented.

Since the core is tightly attached to the hollow molded body, it is difficult to release the hollow molded body from the porous mold.

Since, the hollow molded article has a weak shape retention strength when released from the porous mold, it is difficult to form a complicated shape, and it greatly shrinks during drying or unevenly shrinks to cause drying cracks. It was easy to do.

Furthermore, since the density of the hollow molded body is low, the sintering temperature must be increased, and because the density of the hollow molded body is low and the fiber components are randomly oriented, the strength of the hollow part made by sintering is high. And the toughness was weak.

It is an object of the present invention to provide a method for producing a fiber-reinforced ceramic hollow molded article that can solve the above-mentioned problems.

[Means for Solving the Problems] The present invention has the above-mentioned molding of a fluid body in which a ceramic core and a fiber are mixed with a liquid, in which an expandable and contractible expansion core is arranged inside a molding space of a porous mold. It is pressurized and injected around the space expansion core to absorb or pass the liquid in the fluid by the porous mold to form a preform of ceramic powder and fibers inside the molding space, and then to expand the core. The present invention relates to a method for producing a fiber-reinforced ceramic hollow molded body, which is characterized in that the hollow molded body is molded by expanding and pressurizing the preliminary molded body from the inside.

[Operation] The preformed body is overconsolidated by the expansion of the expansion core, so that a hollow molded body having a uniform density and a high density is formed.

Moreover, at this time, the fiber components in the hollow molded body are oriented parallel to the surface.

Then, the hollow core is easily released from the porous mold by contracting the expansion core.

Since the released hollow molded article has a uniform density and a high density, and the fibers are oriented parallel to the surface, the shape retention strength when released is strong, and the drying shrinkage is small and the drying cracks do not occur during drying. Hard to occur.

Furthermore, since the hollow molded body has a uniform density and a high density and the fibers are oriented parallel to the surface, a hollow component having high strength and high toughness can be obtained when sintered.

Embodiments Embodiments of the present invention will be described below with reference to the drawings.

 1 to 4 show an embodiment of the present invention.

In the figure, 1 and 2 extend inside in the left-right direction in FIG. 1 and are II- in FIG.
A set of porous molds 4 to 7 that support the outer side of the porous molds 1 and 2 from above, below, left and right, and that have a molding space 3 whose cross section in the II direction has a wing shape Frame body, 8 is the porous molds 1 and 2 of the upper and lower frame bodies 4 and 5.
The drainage groove is formed at the boundary between the frame and the left and right frames 6 and 7.

Reference numeral 9 denotes an expansion core that is inserted into the molding space 3 through the insertion opening 10 formed in the frame 7 on the right side of FIG. It is composed of a hollow core body 12 having a core and a rubber core expander 13 covering the core core body 12.

Reference numeral 14 is a holding plate having a protrusion 17 for locking a flange 15 formed at the end of the expansion core 9 on the insertion port 10 side with a step 16 formed at the insertion port 10.

18 is formed in the frame body 6 on the left side of FIG. 1 and supplies a fluid 22 formed by mixing a ceramic powder and a fiber 21 with a liquid into the molding space 3 from a flow path 20 having a valve 19. It is an inlet.

Reference numeral 23 is a blow port formed in the pressing plate 14 and supplying a fluid 26 from the flow path 25 having the valve 24 to the inside of the core core 12 of the expansion core 9.

 Reference numeral 27 is a preformed article, and 28 is a hollow article.

The valve 19 is opened, and inside the molding space 3 of the porous molds 1 and 2, via the flow passage 20 and the injection port 18, the ceramic powder and the fiber 21 such as glass fiber or whisker are used as a binder and a liquid such as water. The fluid 22 formed by mixing the above is injected under pressure over time.

Then, the liquid in the fluid 22 is absorbed by the porosity of the porous molds 1 and 2, or is further passed through the porous parts and discharged from the drainage groove 8 to the outside, that is, drainage is performed and the molding space is formed. A preformed body 27 made of ceramic powder and fibers is formed inside 3.

The preform 27 cast in this way
Has a non-uniform density between the first solidified portion and the solidified portion later, and has a low density because the pressurizing pressure alone is insufficient.

Further, since the orientation of the fiber component 21 is not adjusted, the fiber component 21 of the preform 27 is three-dimensionally and randomly oriented.

Therefore, when the preform 27 is cast-molded, the valve 19 is closed to stop the supply of the fluid 22, and the valve 24 is opened to open the flow path 25 inside the core core 12 of the expansion core 9. The fluid 26 is supplied through the blow-in port 23.

Then, the fluid 26 supplied into the core core 12 expands the rubber core expander 13 covered with the core core 12 through the through hole 11 formed in the core core 12. , The core expander 13 is uniformly displaced in all directions so as to have a similar shape to the molding space 3.

Therefore, each part of the preform 27 is expanded from the inside by the expansion core 9
Is pressed in a direction perpendicular to the inner wall of the molding space 3 to compress the preform 27 and remove liquid from the preform 27 to the outside through the porous molds 1 and 2 and the discharge groove 8. Overconsolidation takes place.

As a result, the hollow molded body 28 having a uniform density and a high density is molded.

Moreover, by over-compacting the preformed body 27, the fiber components in the hollow formed body 28 are oriented parallel to the surface of the hollow formed body 28.

When the hollow molded body 28 is molded, the fluid 26 flows from the expansion core 9.
Is discharged to shrink the core expander 13, the frames 4 to 7 are removed, and the porous molds 1 and 2 are divided to form a gap between the expander core 9 and the hollow molded body 28. The hollow molded body 28 is easily released.

The released hollow molded body 28 has a uniform density and a high density, and the fibers are oriented parallel to the surface, so that the shape retention strength when released is strong and a hollow molded body 28 having a complicated shape is formed. In addition, the drying shrinkage is small and the drying crack is less likely to occur at the time of drying in the subsequent process.

Furthermore, since the hollow molded body 28 has a uniform density and a high density, and the fiber components are oriented parallel to the surface, a high density and high toughness hollow part can be obtained when sintered.

The method for producing the fiber-reinforced ceramic hollow molded article of the present invention is not limited to the above-mentioned examples,
Needless to say, various changes can be made without departing from the scope of the present invention.

[Effects of the Invention] As described above, according to the method for manufacturing a fiber-reinforced ceramic hollow molded article of the present invention, various excellent effects can be obtained as follows.

By over-consolidating the preformed body by the expansion of the expansion core, a hollow molded body having a uniform density and a high density can be formed.

Moreover, at this time, the fiber component in the hollow molded body can be oriented parallel to the surface.

When the hollow molded body is molded, the hollow molded body can be easily released from the porous mold by shrinking the expansion core.

Since the released hollow molded article has a uniform density and a high density and the fibers are oriented parallel to the surface, it is possible to increase the shape-retaining strength when the mold is released, and thus the hollow molded article of a complicated shape can be obtained. Can be molded.

Further, since the hollow molded article has a uniform density and a high density, and the fiber components are oriented parallel to the surface, it is possible to reduce the drying shrinkage during drying and prevent the occurrence of drying cracks.

Furthermore, since the hollow molded body has a uniform density and a high density and the fibers are oriented parallel to the surface, a hollow component having high strength and high toughness can be obtained when the hollow molded body is sintered.

[Brief description of drawings]

FIG. 1 is a sectional view seen from the front showing an example of an apparatus for carrying out the method of the present invention, FIG. 2 is a view taken along the line II-II in FIG. 1, and FIG.
FIG. 4 is a process drawing following FIG. 2, and FIG. 4 is a perspective view showing a hollow molded body molded by the apparatus shown in FIGS. In the figure, 1 and 2 are porous molds, 3 is a molding space, 9 is an expansion core, 21 is a fiber component, 22 is a fluid, 27 is a preformed body, and 28 is a hollow molded body.

Claims (1)

[Claims] 1. A fluid body formed by arranging an expansion core that can expand and contract freely inside a molding space of a porous mold, and mixing a ceramic powder and a liquid with a liquid around the molding space expansion core. It is injected under pressure to absorb or pass the liquid in the fluid by the porous mold to form a preform made of ceramic powder and fibers inside the forming space, and then the expansion core is expanded to form the preform. A method for producing a fiber-reinforced ceramic hollow molded article, which comprises molding the hollow molded article by applying pressure from the inside.