JPH06287650A - Ceramic filter - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to a ceramic filter, and an object thereof is to improve filtration performance. [Structure] A plurality of molten metal flow passages, which are arranged in a matrix form and whose partition walls are made of porous ceramic, are staggered alternately to close open ends of the molten metal flow passages. A ceramic filter for obtaining a filtered molten metal from a melt outlet side opening of an adjacent molten metal passage by filtering the molten metal with a partition wall, and the partition wall of the adjacent molten metal passage is directed toward the molten metal outlet side. It is formed so that the filtration resistance is small.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a ceramic filter.

[0002]

2. Description of the Related Art In general, molten metal contains fine particles of metal oxides, non-metal inclusions, refractories, etc. Therefore, in order to improve the quality of a cast body, such fine particles are used. Need to be removed.

As a method for removing fine particles in molten metal,
Filtration is performed using a glass cloth filter, a ceramic tube filter, or the like. In such a filter, the former has a small filtration capacity because the filtration surface is a single layer, and the latter uses ten or more ceramic tubes, which are fixed with two end plates, which makes it difficult to manufacture and has a thermal shock. It was weak and easily damaged.
(See, for example, Japanese Unexamined Patent Publication No. 1-184237) The inventors have investigated filters proposed in various industrial fields and found that a honeycomb ceramic filter has been proposed for purifying exhaust gas of a diesel engine. It was (Collection of lectures by "Lecture on Environmentally Conscious Materials" (November 27, 1992) Sponsor:
According to this summary, the filter is a honeycomb-shaped tubular body having porous partition walls, and the open ends of the honeycomb conduits are alternately plugged. The exhaust gas flows in through the opening of the honeycomb pipe, and when passing through the partition wall, the dust is filtered and purified, and is exhausted through the opening of the adjacent pipe.

The inventors made a filter having such a structure and tried to filter a molten metal. That is, as shown in FIG. 4, the partition wall 1 of the molten metal flow path 2 is formed of a porous ceramic, and each of the molten metal flow paths 2 is closed at either end of the open portion. The closed portion 8 of the molten metal flow passage 2 is determined so that, for example, the molten metal flow passage 2 closed at the upper end and the molten metal flow passage 2 closed at the lower end are alternately arranged. The so-called checkered pattern is formed by 3 and the closed end 4 as in the honeycomb ceramic filter proposed for the purification of the exhaust gas of the diesel engine described above.

Under the above-mentioned structure, the molten metal flows from the inlet side opening 3a of the lower end face to the molten metal flow path 2 as shown by an arrow in FIG.
After being introduced into the molten metal, it is filtered by the partition wall 1, flows into the adjacent molten metal flow passage 2, and overflows from the open portion 3b at the upper end of the molten metal flow passage 2.

[0006]

DISCLOSURE OF THE INVENTION As a result of an experiment using a molten metal, the inventors have not reached the desired filtering ability to convert the proposed filter into a molten metal, and the partition wall 1 in the filter is not achieved. The vicinity of the upper end does not function as a filtration wall at all,
This seemed to significantly reduce the overall ability to filter. This dead space is 2/3 of the total length in the experiment
Has been reached, which has been an important factor in reducing the filter performance.

Such a phenomenon is considered as follows. That is, before the filtering operation, air is contained in the melt flow path 2, and when the melt is introduced from the melt flow path 2 on the side having the opening at the lower end, the air in the melt flow path 2 is melted. It is pushed by and stays at the upper end of the molten metal flow path 2, then moves to the adjacent molten metal flow path 2 via the partition wall 1 and tries to escape from the filter through the upper end opening.

On the other hand, the molten metal introduced from the open portion 3a at the lower end cannot enter the staying air any more when the staying air pressure at the upper end rises, and immediately passes through the partition wall 1 into the adjacent molten metal flow passage 2. Air 5 flowing in and staying at the upper end of the melt flow path 2 in order to fill the adjacent melt flow path 2 with the melt.
Means that the outlet is blocked and stays at the upper end of the molten metal flow path 2 as it is.

In the above, the deterioration of the filtering capacity when the filter is installed in the vertical direction and the phenomenon thereof have been considered. However, the same filtering capacity also deteriorates when the filter is set in the horizontal direction and the phenomenon also occurs in the vertical direction. It is considered to be similar to the case of installation. However, in the case of horizontal installation, it seems that the smaller the diameter of the molten metal inflow passage, the closer to the result of vertical installation.

The present invention has been made to solve the above drawbacks, and an object of the present invention is to provide a ceramic filter capable of improving the filtering performance.

[0011]

As shown in FIG. 1, a ceramic filter has a plurality of molten metal flow paths 2 arranged in a matrix and partition walls 1 made of porous ceramic.
Equipped with. The open portion of each molten metal flow path 2 is closed, for example, at either the upper end or the lower end.

As in the case of the exhaust gas filter of the diesel engine, the closed portion 8 of the molten metal flow passage 2 is described.
Is determined so that, for example, the molten metal flow paths 2 closed at the upper end and the molten metal flow paths 2 closed at the lower end are alternately arranged, and a checkerboard pattern is formed on the upper and lower end faces of each open end and closed end. Composed.

According to the present invention, the partition walls 1 of adjacent molten metal flow paths 2 are
Is formed so that the filtration resistance becomes smaller as it goes in the direction of the molten metal discharge side, and the change in the filtration resistance is such that the wall thickness of the partition wall 1 is continuously changed as it goes in the direction of the molten metal discharge side. Alternatively, it is realized by discontinuously thinning.

To change the filtration resistance, the partition wall 1 is used.
It is also possible to realize by continuously or discontinuously increasing the aggregate grain size of the porous ceramic constituting the above in the direction of the molten metal discharge side. , Or used together.

[0015]

FIG. 1 is a sectional view showing the principal part of a ceramic filter according to the present invention. As shown by the arrow in FIG. 1, the molten metal is introduced into the molten metal flow path 2 through the opening 3a, and introduces the air in the molten metal flow path 2 into the molten metal flow path 2 while driving it toward the closed end 4 side.

The molten metal introduced into the molten metal flow path 2 is separated by the partition wall 1
As a result, the fine particles are filtered out and flow out into the adjacent melt flow path 2. On the other hand, since the wall thickness of the partition walls 1 of the adjacent molten metal flow paths 2 is gradually thinned in the direction of the molten metal outlet side, the filtration resistance of the molten metal becomes larger on the molten metal inlet side, and the open portion The filtration rate of the molten metal from the partition wall 1 in the vicinity of 3a is regulated.

By regulating the filtration rate of the molten metal on the molten metal inlet side in this way, the timing of filling the molten metal into the adjacent molten metal flow passages 2 is slightly delayed and the molten metal flow passages 2 stay on the closed end 4 side. It is possible to secure the time for the flowing air to escape to the adjacent molten metal flow path 2.

[0018]

EXAMPLES Examples of the present invention will be described below. (Example 1) A ceramic filter in which an aggregate material having an average particle diameter of 2000 μm is bonded with an inorganic binder, a cross section is 110 × 150 mm, a height is 100 mm, a molten metal flow path is 4 × 6 = 24, and an average partition wall thickness is 10 mm. Was manufactured by the following procedure.

That is, first, square pipe members having a square cross section are erected at equal intervals in a matrix on a base, and the outer periphery thereof is surrounded by side plates to produce a molding die. Square pipe is 1.
It is formed with a taper of about 5/100 so that the cross-sectional area becomes smaller toward the free end.

After that, the above-mentioned filter material is charged between the square pipes in the molding die, and then filled by the vibration molding method. Next, after drying the filter material, it is taken out of the molding die and fired in an electric furnace to obtain a vertically long fired body having a plurality of through holes (melt flow paths 2) corresponding to the square pipe material.

Next, after cutting the fired body to a predetermined length, every other end face of the melt flow path 2 is closed. The end face of the melt flow channel 2 is closed by compacting a mixture of fine brown electrofused alumina, fine-grained alumina, and a shape-retaining material in the vicinity of the end face of the melt flow channel 2 and firing again.

As shown in FIG. 3 (a), the ceramic filter obtained as described above has an inclination of 1.5 / 100 and a partition wall 1 that becomes thinner toward the upper end between the molten metal flow paths 2. It has a honeycomb shape that is partitioned. This inclination is appropriately determined by a value at which air on the closed end side in the molten metal flow path 2 escapes, and in the case of the present invention, it is desirable to set it to 1/200 or more, preferably 1/100 or more.

FIG. 3 (b) shows the filtration device used for the performance test of the test filter. This filtration device is provided with a molten metal reservoir 7 communicating with the molten metal introducing portion 6 and a molten metal discharge portion 9 facing the molten metal reservoir 7 via a ceramic filter A, and a molten metal reservoir 7 is passed from an inlet gutter (not shown) to the molten metal reservoir 7. The melt is introduced, and the melt filtered by the ceramic filter A is discharged from the outlet gutter of the melt outlet 9. It should be noted that illustration of a molten metal heating device and the like arranged in the apparatus is omitted.

The molten metal of 6063 alloy is supplied to such a filtration device to perform casting at a speed such that the head difference is 5 to 55 mm, and the ceramic filter after the casting is cut off to connect the metal to the molten metal flow path 2. When the filling state of No. 2 was observed, it was confirmed that the metal was filled up to the upper end in the melt flow path 2 in all cases.

In addition, the presence of fine particles targeted by the ceramic filter was not confirmed in the ingot produced by filtering with the ceramic filter. (Embodiment 2) The wall thickness of the partition wall 1 in the above-mentioned embodiment is fixed to 10 mm from the upper end to the lower end, and only the aggregate grain size is 1500 μm in the lower 1/3 and 2000 μ in the middle 1/3.
m, the upper 1/3 was 3000 μm, and a ceramic filter was manufactured in three steps, and a filtration test was conducted on the test filter under the same conditions as described above. As a result, the entire molten metal flow path 2 was filled with metal. Was confirmed, and the presence of harmful fine particles in the ingot was not confirmed.

(Example 3) A ceramic filter in which the aggregate particle size of the partition wall 1 in Example 1 was changed in three stages, that is, the lower 1/3 was 1500 μm, the middle 1/3 was 2000 μm, and the upper 1/3 was 3000 μm. Was subjected to a filtration test under the same conditions as described above with the test filter, it was confirmed that the entire melt flow path 2 was filled with metal, and further that harmful microparticles were present in the ingot. Was not confirmed.

(Comparative Example) The aggregate particle size in Example 2 was set to 2
When a filtration test was performed under the above conditions while keeping the air flow rate constant at 000 μm, it was confirmed that there was no metal filling in the upper 2/3 of the molten metal flow path 2 opening at the lower end, and that air remained.

[0028]

As is apparent from the above description, according to the present invention, the partition walls 1 of the adjacent molten metal flow passages 2 are formed so that the filtration resistance becomes smaller toward the outlet side of the molten metal. , The air accumulated on the closed end 4 side of the molten metal flow path 2
It can be surely pushed out to the adjacent molten metal flow paths 2.

As a result, since the partition wall 1 between the molten metal flow paths 2 can be used as the filtration wall over the entire length, the filtration efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment of the present invention.

FIG. 2 is a sectional view of an essential part showing another embodiment of the present invention.

FIG. 3 is an external view of a ceramic filter and a diagram showing a filtration device.

FIG. 4 is a diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Partition wall 2 Molten metal flow path 3 Opening part 4 Closing end 6 Molten metal introducing part 7 Molten metal reservoir 8 Closing part 9 Molten metal outlet part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuo Hayashi 1-34-1 Kambara, Kambara-cho, Anbara-gun, Shizuoka Prefecture Nichiru Giken Co., Ltd. (72) Inventor Hiroshi Mochizuki 161 Kambara-cho, Anbara-gun, Shizuoka Japan Light Metal Co., Ltd. in Kambara Works

Claims (3)

[Claims] 1. A plurality of molten metal flow passages arranged in a matrix form, the partition walls of which are made of porous ceramic, are alternately closed to open the molten metal flow passages. A ceramic filter that obtains a filtered molten metal from a molten metal outlet side opening of an adjacent molten metal flow path by filtering the formed molten metal by a partition wall, wherein the adjacent molten metal flow channel partition wall is directed toward the molten metal outlet side. A ceramic filter that is formed so that the filtration resistance becomes smaller. 2. The ceramic filter according to claim 1, wherein the partition walls of the adjacent molten metal flow passages are made thinner toward the molten metal outlet side. 3. The ceramic filter according to claim 1, wherein the partition walls of the adjacent molten metal flow passages have an aggregate particle size that increases toward the molten metal outlet side.