JP3519937B2 - Molten metal holding pipe - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a molten metal holding pipe. More specifically, the present invention relates to a molten metal holding pipe that can be used as a pipe for forming a riser at the time of casting production, a pipe forming a side surface portion of a molten metal collecting container, and the like.

[0002]

2. Description of the Related Art Conventionally, when manufacturing a casting, a riser has been required to prevent casting defects. However, since this feeder is essentially unnecessary, it needs to be removed. Therefore, there are various wastes such as a large amount of metal is required, a large amount of metal is required to be melted, and the feeder is required to be removed.

In order to eliminate such waste, a dielectric coil is loosely fitted on the outside of a refractory pipe which is embedded in the mold so as to communicate with the mold cavity and stands upright, and the induction coil is used for refractory when pouring metal. A method is known in which the molten metal in the pipe is induction-heated to solidify the molten metal in the refractory pipe. According to this method, the feeder can be made small and a small amount of metal can be used, so that it is possible to reduce the trouble of melting and the trouble of removing the feeder.

By the way, the following heat resistance is required for the refractory pipe which occupies an important specific gravity in this method. In other words, the molten metal at 1,200 ° C to 1,500 ° C is 2
It is necessary for the refractory pipe to be able to hold the molten metal inside without cracking, either by holding it for 0-40 minutes, or by heating the molten metal with an inductive coil. Therefore, we used ceramic pipes and extruded pipes as the fire resistant pipes, but these fire resistant pipes have low thermal shock resistance (brittle) and easily crack, so
It was difficult to use. On the other hand, fire-resistant pipes made by suction molding using ceramic fibers have low strength,
It is difficult to use because it cannot shield molten metal.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and can hold molten metal without cracking even if it is held for a long time, and has strength and shielding property of molten metal. The purpose is to provide excellent pipes.

[0006]

In the molten metal holding pipe of the present invention, an inorganic fiber sheet is wound and laminated via an inorganic shielding layer containing an inorganic powder and an inorganic adhesive, The total mass with the inorganic adhesive is at least twice the mass of the inorganic fiber sheet. As described above, since the molten metal holding pipe of the present invention uses the inorganic fiber sheet, it does not crack even if the molten metal is held for a long time and is excellent in strength. Further, since the inorganic shielding layer containing a large amount of the inorganic powder and the inorganic adhesive is formed, the shielding property of the molten metal is excellent.

The above inorganic powder has an average particle size of 10 μm.
In the molten metal holding pipe in which the mixed particles of less than 100 μm and the average particle diameter of 10 to 100 μm are mixed, since the inorganic powders can be easily arranged in a dense state, the strength can be further improved, and It also has better shielding properties.

Further, the molten metal holding pipe having an alkali metal oxide content of 2 mass% or less in the whole inorganic material is excellent in heat resistance because the melting point of the inorganic component is not easily lowered, and cracking is less likely to occur.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The inorganic fiber sheet of the present invention is mainly composed of inorganic fibers so as to have excellent heat resistance, and the presence of this inorganic fiber sheet imparts thermal shock resistance to the molten metal holding pipe. The form of this fiber sheet may be, for example, a woven fabric, a knitted fabric, or a non-woven fabric, but is preferably a non-woven fabric so that it is excellent in retaining inorganic powder and the like. This suitable nonwoven fabric can be produced, for example, by a conventional wet papermaking method or a dry method, but it is more preferably produced by a wet papermaking method having excellent uniformity.

As the inorganic fiber constituting the inorganic fiber sheet, for example, one or more kinds of silica-alumina fiber, alumina fiber, silica fiber, glass fiber, carbon fiber, silicon carbide fiber, rock wool, metal fiber and the like are used. it can. Among these, silica-alumina fibers, alumina fibers, silica fibers, or silicon carbide fibers, which are excellent in maintaining fiber strength at high temperatures, can be preferably used.

The inorganic fiber sheet according to the present invention may contain at least 50 mass% of inorganic fibers.
It preferably contains 70 mass% or more of inorganic fibers, and more preferably 90 mass% or more of inorganic fibers. Incidentally, as the fibers other than the inorganic fibers constituting the inorganic fiber sheet, within a range that does not adversely affect heat resistance and the like, meta- or para-based aromatic polyamide fiber, polyamideimide fiber, polytetrafluoroethylene fiber, aromatic Heat resistant fibers such as group polyether amide fibers and polybenzimidazole fibers, and in some cases, recycled fibers, semi-synthetic fibers, synthetic fibers, plant fibers, and animal fibers can also be included.

The fiber diameter of the fibers constituting the inorganic fiber sheet is preferably 0.5 to 20 μm, and more preferably 1 to 10 μm so that the fiber diameter is excellent.
Further, the fiber length is preferably 1 mm or more so as to have excellent thermal shock resistance. When a nonwoven fabric is produced by a suitable wet papermaking method, it is preferably 20 mm or less in length in terms of production.

The apparent density of this inorganic fiber sheet is 0.05 to 0.5 so that it has excellent thermal shock resistance and morphological stability.
g / cm ³ is preferred, 0.1-0.3 g / c
More preferably m ³ .

In the molten metal holding pipe of the present invention, the above-mentioned inorganic fiber sheet is adhered via the inorganic shielding layer containing the inorganic powder and the inorganic adhesive. As the inorganic adhesive, for example, silica sol, alumina sol, zirconia sol, silicate, phosphate, or alumina cement,
It is possible to use one or more cements such as magnesia cement and zirconia cement.

As the inorganic powder, for example, feldspar,
Magnesia, diatomaceous earth, silica, silica alumina, mullite, alumina, aluminum hydroxide, zircon, zirconia, titanium oxide, magnesium oxide, calcium oxide, calcium silicate, magnesium silicate, shirasu, shirasu balloon, perlite, glass, glass balloon , Dolomite, chamotte, mica, cordierite, silicon nitride, boron nitride, silicon carbide, boron carbide, metal powder, carbon powder, or kaolin, bentonite, rock stone, talc, bayerite, diaspore,
Sepiolite, attapulgite, montmorillonite,
Clay minerals such as hectorite, synthetic fluoromica and smectite can be used.

When clay minerals are included among these inorganic powders, the heat resistance and the smoke resistance are excellent, and the viscosity of the mixed liquid of the inorganic powder and the inorganic adhesive can be adjusted so that the inorganic powder can be made uniform. It can be preferably used because it has an effect of dispersing. This clay mineral preferably accounts for 1 to 30 mass% of the whole inorganic powder. If it is less than 1 mass%, it is difficult to adjust the viscosity, and it tends to be difficult to uniformly disperse the inorganic powder. If it exceeds 30 mass%, the liquid retaining property of the mixed solution becomes high, and a large amount of the inorganic powder and This is because the strength tends to decrease due to the inability to form an inorganic shielding layer made of an inorganic adhesive or the inability of powder to penetrate into the inorganic fiber sheet, and more preferably 3 to 20 mass%. The viscosity may be adjusted by using sodium silicate, ultrafine particles having a particle size of 1 μm or less, or an organic polymer as a part of the clay mineral or instead thereof.

This inorganic powder has an average particle size of 0.1.
~ 100 μm can be used, but the average particle size is 10 μm
If the average particle size is less than 10 μm and the average particle size is 10 μm to 100 μm, the inorganic powder can be easily arranged in a dense state, the strength of the molten metal holding pipe can be further improved, and the molten metal shielding property can be improved. Is also preferable because it is excellent.
In addition, when used in combination, a uniform inorganic shielding layer containing a large amount of inorganic powder and an inorganic adhesive can be formed, so that there is an effect that it is more excellent in shielding the molten metal. Furthermore,
Since it is possible to provide a difference in the distribution state of the inorganic powder and the inorganic adhesive in the thickness direction of the inorganic fiber sheet, there is an effect that cracks are less likely to occur.

When this inorganic powder is used in combination, the average particle size is 1
Inorganic powder less than 0 μm and average particle size 10 μm to 100 μm
The mass ratio of the inorganic powder to the inorganic powder is 1: 9 to 9: 9 so that an inorganic shielding layer containing a large amount of inorganic powder can be formed and a uniform inorganic shielding layer having excellent processability can be formed. It is preferably 1, and more preferably 3: 7 to 7: 3. The inorganic powder having an average particle size of less than 10 μm and the inorganic powder having an average particle size of 10 μm to 100 μm may be the same type or different types. Further, inorganic powder having an average particle size of less than 10 μm and / or average particle size of 10 μm to 100 μm
The above inorganic powder may be composed of at least one kind.

Further, the ratio (solid content) of the inorganic powder and the inorganic adhesive is such that the adhesive strength is excellent and that the inorganic shielding layer containing a large amount of the inorganic powder and the inorganic adhesive can be formed.
It is preferably from 99: 1 to 50:50, and from 95: 5.
It is more preferably 70:30.

The molten metal holding pipe of the present invention comprises an inorganic fiber sheet wound and laminated through the above-mentioned inorganic shielding layer, and the total mass of the inorganic powder and the inorganic adhesive is the inorganic type. At least twice the mass of the fiber sheet (preferably 2.
5 times or more, and more preferably 3 times or more), so that the molten metal is excellent in shielding property.

The content of the alkali metal oxide in the entire inorganic material is 2 mass% or less (preferably 1.5).
It is preferable for the content to be less than or equal to mass%, more preferably less than or equal to 1 mass%, and most preferably less than or equal to 0.5 mass%) because the melting point of the inorganic component is unlikely to drop and cracking is less likely to occur when holding the molten metal. Although the alkaline earth metal oxide has a smaller effect of lowering the melting point of the inorganic component than the alkaline metal oxide, it has the effect of causing the lowering of the melting point, so that the alkaline metal oxide and the alkaline earth metal oxide are inorganic materials. The total content in the whole is preferably 3 mass% or less, and 2.5 mass
It is more preferably s% or less, and most preferably 2 mass% or less. The inorganic material means a material composed of an inorganic component forming a molten metal holding pipe, such as an inorganic fiber, an inorganic powder or an inorganic adhesive. Therefore, as the inorganic fiber, silica-alumina fiber, alumina fiber,
Silica fibers, silicon carbide fibers and the like can be preferably used.
Further, as the inorganic powder, diatomaceous earth, silica, silica alumina, mullite, alumina, aluminum hydroxide,
Zircon, chamotte, pearlite, zirconia, titanium oxide, silicon nitride, boron nitride, silicon carbide, boron carbide, metal-based powder, carbon-based powder and the like can be preferably used. Further, as the inorganic adhesive, silica sol, alumina sol, zirconia sol, etc. can be preferably used.

The molten metal holding pipe of the present invention as described above can be manufactured, for example, as follows. First, an inorganic fiber sheet, a mixed solution of inorganic powder and an inorganic adhesive, and a core material that shrinks by drying (hereinafter referred to as “shrinkable core material”) are prepared.

Next, a mixed solution of inorganic powder and an inorganic adhesive is applied to the inorganic fiber sheet and then wound around the shrinkable core material. As a method of applying a mixed solution of an inorganic powder and an inorganic adhesive to this inorganic fiber sheet, for example, using a coating machine such as a roll coater, a knife coater, a curtain coater, coating on one side of the inorganic fiber sheet And a method of impregnating the entire inorganic fiber sheet with an impregnation coater or the like. Among these, if only one side is coated with a coating machine, it is easy to control the applied amount constant,
Moreover, it is preferable because it is excellent in working environment.

Further, since the mixed solution of the inorganic powder and the inorganic adhesive forms the inorganic shielding layer, it is preferable that a larger amount of the mixed solution can be applied. Therefore, the viscosity of the mixed solution is preferably about 100 to 10,000 cps.

As a method of winding the inorganic fiber sheet to which the mixed solution of the inorganic powder and the inorganic adhesive is applied around the shrinkable core material, there is, for example, a method of flat winding or spiral winding. This inorganic fiber sheet may be wound on the shrinkable core material in any number of layers, but it may be wound in three or more layers so as to be uniform, strong and excellent in molten metal shielding property. Preferably.

Next, an inorganic fiber sheet in which the above-mentioned mixed solution is applied to the shrinkable core material is wound and dried, and then the shrinkable core material is pulled out to manufacture the molten metal holding pipe of the present invention. You can That is, since the shrinkable core material swollen when the inorganic fiber sheet to which the mixed solution is applied is wound around the shrinkable core material, the shrinkable core material shrinks when dried, so that the molten metal holding pipe is easily removed without damage. It is possible.

The shrinkable core material varies depending on the solvent constituting the mixed solution. For example, when the solvent is aqueous, a shrinkable core material made of a cellulosic material such as paper or wood is used. Is preferred. More specifically, when the solvent is water-based, a paper tube, a log material, a square material, or a molded water-soluble polymer can be used.

The drying method may be heating or air drying. In the case of air drying, it is more preferable to dehumidify so that the shrinkable core material can be easily extracted.

Examples of the present invention will be described below, but the present invention is not limited to the following examples.

[0030]

EXAMPLES (Examples 1 to 5, Comparative Example) Silica-alumina fibers (fiber diameter: 2 to 3 μm, fiber length: 1 to 10 mm) were bonded by a polyvinyl alcohol fiber of 3 mass% by a wet papermaking method, an areal density of 100 g. / M ² , thickness 0.5m
An inorganic non-woven fabric having m and an apparent density of 0.2 g / cm ³ was produced.

Then, an aqueous solution containing the inorganic powder and the inorganic adhesive as shown in Table 1 was applied on one surface of the above-mentioned inorganic non-woven fabric by a roll coater in the amount shown in Table 1. Next, the paper tube whose surface has been made water resistant (inner diameter 50 mm, outer diameter 6
0 mm), an inorganic non-woven fabric coated with an aqueous solution containing inorganic powder and an inorganic adhesive was flatly wound 5 times. Then 40
After drying for 10 hours while ventilating at 0 ° C., the paper tube was extracted and cut to produce a molten metal holding pipe having a length of 500 mm and an outer diameter of 66 mm.

[0032]

[Table 1]

Example 6 An aqueous solution containing an inorganic powder and an inorganic adhesive as shown in Table 2 was rolled by a roll coater.
Coating on the same inorganic non-woven fabric as in Example 1 (500 g / m ² ).
Except for the above, the length was 50
A molten metal holding pipe having a diameter of 0 mm and an outer diameter of 66 mm was manufactured.

[0034]

[Table 2]

(Winding workability) When manufacturing the molten metal holding pipes of Examples 1 to 6 and Comparative Example,
The results of the winding workability are shown in Tables 1 and 2. From these results, it is understood that the winding workability is excellent when the inorganic powder having an average particle size of less than 10 μm and the inorganic powder having an average particle size of 10 to 100 μm are mixed.

(Heat Resistance Test) The molten metal holding pipes of Examples 1 to 6 and Comparative Example were each embedded in a furan mold at a portion up to about 60 mm (perpendicular to the furan mold) to hold the molten metal. The lower end of the pipe was blocked. Then, inside each molten metal holding pipe, a temperature of about 1,
Molten metal at 300 ° C. was poured from the lower end of the molten metal holding pipe to a height of about 400 mm. Then, the molten metal inside from the periphery of the molten metal holding pipe was heated by a high frequency dielectric heating device to maintain the temperature of the molten metal at about 1,300 ° C. for 30 minutes. Then, the state of each molten metal holding pipe was observed. The results are also shown in Tables 1 and 2.

From these results, (1) the heat resistance is excellent when the content of the alkali metal oxide in the whole inorganic material is 2 mass% or less, and (2) the total of the inorganic powder and the inorganic adhesive. When the mass is 2 times or more (particularly 3 times or more) that of the inorganic non-woven fabric, the heat resistance is more excellent, and (3) the inorganic powder having an average particle size of less than 10 μm and the average particle size of 10 to 100 μm. It can be seen that when the inorganic powder of No. 1 is mixed, the heat resistance is more excellent.

[0038]

In the molten metal holding pipe of the present invention, the inorganic fiber sheet is wound and laminated via the inorganic shielding layer containing the inorganic powder and the inorganic adhesive, and the inorganic powder and the inorganic adhesive are Is more than twice the mass of the inorganic fiber sheet. As described above, since the molten metal holding pipe of the present invention uses the inorganic fiber sheet, it does not crack even if the molten metal is held for a long time and is excellent in strength. Further, since the inorganic shielding layer containing a large amount of the inorganic powder and the inorganic adhesive is formed, the shielding property of the molten metal is excellent.

The above inorganic powder has an average particle size of 10 μm.
In the molten metal holding pipe in which the mixed particles of less than 100 μm and the average particle diameter of 10 to 100 μm are mixed, since the inorganic powders can be easily arranged in a dense state, the strength can be further improved, and It also has better shielding properties.

Further, the molten metal holding pipe having an alkali metal oxide content of 2 mass% or less in the whole inorganic material is excellent in heat resistance and is less likely to be cracked because the melting point of the inorganic component is not easily lowered.

Claims (3)

(57) [Claims] 1. An inorganic fiber sheet is wound and laminated via an inorganic shielding layer containing an inorganic powder and an inorganic adhesive, and the total mass of the inorganic powder and the inorganic adhesive is equal to that of the inorganic fiber sheet. A molten metal holding pipe having a mass of at least twice the mass. 2. The molten metal holding pipe according to claim 1, wherein inorganic powders having an average particle size of less than 10 μm and those having an average particle size of 10 to 100 μm are mixed. 3. The molten metal holding pipe according to claim 1, wherein the content of the alkali metal oxide in the whole inorganic material is 2 mass% or less.