JPH0676626B2 - Whisker preform filtration molding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to whiskers used as a fibrous skeleton for producing a fiber-reinforced composite material by infiltrating or impregnating a matrix material such as a metal-based or plastic-based material The present invention relates to a preform filtration molding apparatus, and more particularly to an improved filtration molding apparatus capable of forming the upper surface of a molding whisker into a desired height and shape.

[Conventional technology]

As a method of manufacturing a fiber-reinforced composite material using whiskers such as SiC, Si ₃ N ₄ , and Al ₂ O ₃ as a reinforcing material, a preformed whisker aggregate preform is placed in a predetermined mold, and a liquid A pressure casting method (molten forging method) in which a matrix substance is infiltrated or impregnated under pressure is regarded as a practical means. The composite material obtained by this method is extremely tough and therefore difficult to cut. Therefore, it is desired that the whisker preform is produced in advance in a shape that conforms to the final application part.

Usually, the whisker preform is obtained by filtering a slurry in which the whisker product is dispersed in water or an organic solvent under normal pressure or under pressure, and then drying the wet whisker cake obtained as it is or compressed to a predetermined density. Filtration molding method (Japanese Patent Laid-Open No. 59-121196, No. 60-
161400).

According to the above-described filtration molding method, it is possible to form a benign whisker preform having an extremely homogeneous integrated structure structure while being a whisker-only aggregate, but the obtained preform shape is relatively simple. Limited to
There is a drawback that the molding height cannot be adjusted and complex shapes cannot be formed. Therefore, in order to meet the demand for a specific shape, a method has been adopted in which a preform once filtered and molded is processed into a desired shape by cutting or the like. However, because the preform has a fragile structure, it requires a great deal of time and material loss for accurate processing, and often suffers damage during processing.

In order to deal with such a situation, the present applicant flows the whisker dispersion into a filtration tank containing a porous female mold of a desired shape to perform a filtering operation, and then the whiskers are completely filled from the filtration tank. Molding method of whisker preform for composite material in which porous female mold is collected and wet whisker molded body is dried (JP-A-61-143533), or the inner surface shape of the filter member at the bottom of the filter tank corresponding to the final FPM Overmolding machine formed by the porous body of
Have already proposed.

[Problems to be Solved by the Invention]

However, among the above-mentioned prior arts, the molding method disclosed in Japanese Patent Laid-Open No. 61-143533 has complicated steps and often suffers from material damage when releasing the whisker preform from the porous female mold. . Further, in the case of the apparatus described in Japanese Utility Model Laid-Open No. 63-145852, a pattern of a predetermined shape is formed on the bottom of the preform to be molded, but the upper surface of the filter tank is an open space, so the preform is formed. There is a problem in that the molding height of the upper surface cannot be adjusted accurately and the shape cannot be made into a desired shape.

The present invention has been made to solve the above-mentioned problems of the prior art, and its object is to particularly filter-form a whisker preform capable of forming the upper surface into a desired height or shape. To provide.

[Means for Solving the Problems]

The whisker preform filtration molding apparatus according to the present invention for achieving the above object is a filter tank in which a lid portion provided with a gas introduction pipe at the upper portion and a filtrate discharge mechanism having a filter member provided at the bottom portion are detachably mounted. In the above, the structural feature is that a small hole or a slit is formed at a position corresponding to the preform molding upper surface of the filtration tank, or the upper surface molding member is provided in a state where the slit is formed.

[Action]

The formation of whisker preforms is carried out by a process in which a slurry in which whiskers are uniformly dispersed flows into a filter tank and is subjected to a filtration treatment while injecting air from a gas introduction pipe.
At this stage, the slurry is injected from the small holes or slits of the upper surface molding member into the molding compartment partitioned by the upper surface molding member and the filter member. The injection of the slurry at this stage serves to dismantle the flocs of the whiskers that have secondarily aggregated.

As the filtration progresses, the whiskers gradually deposit in the molding section, fill the molding section as a cake, and then deposit up to the upper part of the upper molding member.

At this time, the upper surface molding member functions to adjust the whisker preform to be formed to a predetermined height or to mold the upper surface into a desired shape.

In the process of separating the filtration tank from the mold after the completion of filtration, the molding preform is easily cut from the site of the small holes or the slits, and thus almost no cutting trace remains.

The above actions synergistically enable efficient formation of a homogeneous whisker preform having good surface properties and a height and shape according to the molding section and high dimensional accuracy.

〔Example〕

 Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a vertical cross-sectional view showing an example of the filtration molding apparatus according to the present invention, FIG. 2 is a cross-sectional view taken along the line AA ′ in FIG. It is composed of a lid part 3 provided with 2 and a filtrate discharge mechanism 6 having a large number of filtrate circulation holes 5 having a filter member 4 provided on the bottom thereof, and each part is hermetically attached in a separable state. ing. The side wall of the filter tank 1 has a cylindrical shape, a rectangular tube, or the like according to the purpose, and in the case of a complicated shape, a split mold structure can be used to facilitate the release of the molding preform.

The filter member 4 is selected from a filter cloth such as a woven cloth and a non-woven cloth, and a filter material that withstands a molding pressure at the time of filtration, such as stainless steel or nylon mesh, but it is preferable to use one having a smooth surface as much as possible. . It is also possible to configure the filter member with a porous sintered metal or ceramic material that has been processed into a predetermined shape in advance.

Inside the filter tank 1, an upper surface molding member 7 having a small hole or a slit formed at a position corresponding to the molding upper surface (molding height) of the whisker to be formed is interposed, and the filter tank between the filter member 4 and the upper surface molding member 7 is interposed. A molding section 8 is formed in the portion. In FIG. 1, an upper surface molding member 7 for forming the upper surface of the preform into a step shape.
As an example, a small hole 9 is formed in the central portion, but the examples in FIGS. 5 and 6 show an example in which the slit 10 is formed in the upper surface molding member 7 having a step. Further, as a mode of interposing the upper surface molding member 7 in the state where the slit is formed, as shown in FIGS. 7 and 8, the core 11 is set in the inside of the filter tank 1 and The slit 10 may be formed between the child 11 and the inner peripheral surface 12 of the upper surface molding member 7. This example is particularly effective when forming a ring-shaped whisker preform having a through hole in the central portion.

The small hole 9 or the slit 10 formed or formed in the upper surface molding member 7 may be one or plural, but in the case of the small hole 9, the diameter is 0.5 to 10 mm, and in the case of the slit 10, the slit width. It is desirable to set it appropriately within the range of 0.1 to 3 mm according to the shape dimension of the molding preform.
If the diameter or slit width is less than the above range, the filtration will not proceed smoothly. On the other hand, if it exceeds this range, a large cutting trace remains at the time of mold release, resulting in deterioration of surface properties.

When molding the whisker preform, SiC, Si ₃ N
A slurry 13 in which whiskers such as ₄ , Al ₂ O _{3 and the} like are stirred and dispersed in water or an appropriate organic solvent is flown into the filter tank 1 to cover the lid portion 3 and air is forced in through the gas introduction pipe 2. The air pressure is set within the range of 0.5 to ⁶ kg / cm ² . At this stage, the slurry is injected into the molding section 8 through the small holes 9 (slits 10 in FIGS. 5 to 8) and is gradually deposited as a cake 14 (state in FIG. 1).

As the filtration progresses, the whisker cake 14 fills the molding section 8 and a part of the cake is deposited on the upper surface of the upper molding member 7 (third part)
When the figure is reached, complete the filtration. When the filtration is completely completed, the lid 3 is removed, and the filter tank 1 is gently moved upward to release the mold (the state of FIG. 4, in the case of FIG. 7, the core 11 is also removed at the same time). In this case, the molding preform in the molding section and the whiker cake on the upper molding member 7 are easily cut from the small holes 9 (slits 10 in the case of FIGS. 5-8).

By such a process, the whisker preform 15 having a dimension and shape along the predesigned molding section is formed.

A small hole 9 having a diameter of 1 mm is formed in the central portion, and an upper surface molding member 7 whose lower surface is a flat surface is installed at a height of 10 mm from the filter member 4 by using the filtration molding apparatus of the structure shown in FIG. 1 (inner diameter 40 mm).
Filtration was performed under the following conditions to form a disc-shaped whisker preform.

Whiskers: SiC whiskers Slurry: water dispersion, dispersion concentration 100g / l Air pressure: 3kg / cm ² Almost no traces of cuts from small holes were observed in the molded SiC whiskers preform. The diameter and height of the dried whisker preform were measured (sample number: 5). For comparison, a SiC whisker preform formed by the conventional filtration molding method was cut to the same size 2
The dimension of the next processed product (Comparative Example) was also measured, and the results are compared and shown in Table 1.

From the results shown in Table 1, it is recognized that the example is superior in dimensional accuracy particularly in height as compared with the comparative example.

〔The invention's effect〕

As described above, according to the whisker preform filtration molding apparatus of the present invention having the above-mentioned structural functions, the height and shape of the upper surface of the molding preform can be formed with good dimensional accuracy as desired in particular.

Therefore, a whisker preform having a shape conforming to the required composite material can be produced without secondary processing, and the industrial and economic effects are significant.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view exemplifying a whisker preform filtration molding apparatus according to the present invention, and FIG. 2 is AA ′ of FIG.
3 and 4 are partial longitudinal sectional views of the apparatus showing the stages of the filtration process. FIG. 5 is a partial vertical sectional view showing another embodiment, and FIG. 6 is AA ′ in FIG.
A sectional view, FIG. 7 is a partial vertical sectional view showing another embodiment, and FIG. 8 is a sectional view taken along the line AA 'in FIG. DESCRIPTION OF SYMBOLS 1 ... Filter tank, 2 ... Gas introduction pipe 3 ... Lid part, 4 ... Filter member 5 ... Filtrate flow hole, 6 ... Filtrate discharge mechanism 7 ... Upper surface molding member, 8 ... Molding section 9 ... Small hole, 10 ... Slit 11 ... Core, 12… Inner surface 13… Slurry, 14… Cake 15… Whisker preform

Claims (2)

[Claims] 1. A filter tank in which a lid part provided with a gas introduction pipe in the upper part and a filtrate discharge mechanism in which a filter member is installed in the bottom part are separably mounted, and at a position corresponding to the upper surface of preform molding of the filter container. An apparatus for forming a whisker preform by forming an upper surface molding member in the state of forming a small hole or a slit or in a state where the slit is formed. 2. A mode in which an upper surface molding member is provided in a state where a slit is formed is such that a core is set inside a filtration tank and a slit is formed between the core and the inner peripheral surface of the upper surface molding member. The whisker preform filtration molding apparatus according to claim 1, which has a structure to be formed.