JP2002160052A - Melting holding furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pot type melting holding furnace, which is free from such danger that brings about a vapor explosion even though a pot is broken, and moreover, makes it easy to exchange an inner case which is embedded with an induction coil. SOLUTION: A melting pot 3 is stored in a body 2 of a furnace which is provided with a fire resisting layer 8 around its inner side in a condition that a space 10 is provided between the fire resisting layer 8 and the melting pot 3. An inner case 6 of the body 2 of the furnace which is embedded with the induction coil 9 inside the fire resisting layer 8, is made as a cartridge type case detachable from an outer case 5, so that the inner case 6 in which the induction coil 9 is embedded can be exchanged easily.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a melting and holding furnace for producing a molten metal to be cast into a mold or a sand casting mold.

[0002]

2. Description of the Related Art Several methods and structures have been proposed for a melting and holding furnace for producing a molten metal to be cast into a mold.
The crucible induction melting furnace is one of them.

In a conventional crucible-type induction melting furnace, a coil using a steel pipe that is inexpensive and easy to process is arranged on the outer periphery of a crucible-type melting chamber. The structure is such that the material is dissolved by the eddy current due to the action.

[0004]

Incidentally, the coil using a steel pipe employed in the above-mentioned conventional crucible type induction melting furnace is oxidized at a high temperature unless cooled when energized.
Generally, cooling is performed using water as a coolant. Therefore, when the crucible is broken and the molten metal breaks the steel pipe, or when the steel pipe is cracked and the cooling water flows out, there is a risk that the molten metal reacts with the cooling water to generate a steam explosion.

In addition, when the induction coil attached to the outer periphery of the crucible needs to be replaced after its useful life, there is a problem that the replacement operation is difficult to perform.

Accordingly, an object of the present invention is to provide a crucible-type melting and holding furnace in which there is no danger that steam explosion will occur even if the crucible is broken, and the inner case in which the induction coil is embedded can be easily replaced. (Induction furnace).

[0007]

According to the present invention, a crucible is provided inside a furnace body having a refractory layer provided on an inner periphery thereof, and a gap is provided between the refractory layer and the crucible. It is stored in a state, and an induction coil is buried in the refractory layer of the furnace body,
This induction coil employs a configuration in which a heat-resistant insulating material is wound around the induction coil, and the outside thereof is coated with a heat-resistant caster.

The induction coil can be made of a heat-resistant material with low electric resistance, such as nickel or inconel, and can be made into a cartridge type that can be replaced with the refractory layer of the furnace body.

Further, the crucible may have a structure in which a fire-resistant melting barrier layer for covering the buried induction coil is provided on the inner peripheral surface thereof.

Here, since a gap is provided between the furnace main body and the crucible, a molten metal leak detecting means is disposed in the gap, so that even if the crucible is broken, the molten metal leak can be detected quickly. In addition, due to the formation of the gap and the structure of the fusion blocking layer, reliable explosion-proof measures can be taken.

[0011]

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

As shown, the melting and holding furnace comprises a furnace body 2 movable along a rail 1, a crucible 3 housed therein, and a lid member 4 arranged on the crucible 3. The main body 2 accommodates the inner case 6 in a cartridge type inside the outer case 5. The inner case 6 is provided with a refractory layer 8 on the inner periphery of the outer wall 7, and the induction coil 9 is embedded in the refractory layer 8.
On the inner peripheral surface of the refractory layer 8, a melting barrier layer 18 made of a refractory material is provided so as to cover the buried induction coil.

The crucible 3 is supported by the outer case 5 and fits inside the inner case 6, and a crack formed in the crucible 3 is provided between the outer surface of the crucible 3 and the inner peripheral surface of the refractory layer 8 of the inner case 6. A gap 10 is formed to allow the molten metal to escape downward when the molten metal leaks from the furnace. A drain hole 11 is provided at the lower part of the furnace body 2, and a drain chute 1 disposed immediately below the drain port 11.
2 is provided with a hot water leak detection sensor 13.

The induction coil 9 is made of a material having a low heat resistance such as nickel or inconel and has a low electric resistance. The induction coil 9 is spirally arranged so as to surround the internal space with respect to the refractory layer 8. The diameter is covered with an antioxidant material 14, a heat-resistant insulator 15 is wound therearound, and the outside is coated with a heat-resistant caster 16. The cartridge type is removable on the outer wall 7 of the inner case 6 and can be replaced with a fixing base 17 for removal. The induction coil 9 is attached and covered with the melting barrier layer 18 so as not to be exposed on the inner surface of the inner case 6, so that even if the molten metal leaks out of the crucible 3, the induction coil 9 is not affected at all.

In the case of FIG. 1, the induction coil 9 is divided and arranged in a plurality from the peripheral wall of the refractory layer 8 to the bottom, but may be disposed only on the peripheral wall portion of the refractory layer 8.

The melting and holding furnace of the present invention is configured as described above. A material is put into the crucible 3 supported by the furnace main body 2 and the induction coil 9 of the inner case 6 is energized to induce crucible by induction heating. 3 is heated, a predetermined amount of molten metal A is produced by charging a predetermined amount of material and induction heating, and hot water may be supplied to a mold.

At this time, since the heating method using the induction coil 9 is induction heating, the temperature of the induction coil 9 is hardly higher than that of the crucible 3, and the crucible 3 is cracked and the molten metal A leaks out of the crucible 3. In such a case, the molten metal A passes through the gap 10 between the inner circumference of the refractory layer 8 and the outer circumference of the crucible 3, flows along the outer surface of the crucible 3, flows to the bottom, and flows to the drain chute 12 disposed immediately below the drain hole 11. The molten metal leak is detected by the molten metal leak detection sensor 13 and an alarm is issued, so that the occurrence of the molten metal leak in the crucible 3 can be notified. The occurrence can be prevented beforehand.

The induction coil 9 is buried in the refractory layer 8 of the inner case 6 and is covered with the melting barrier layer 18 and is made of a solid wire that does not require cooling. In the case where the molten metal leaks out in 3, there is no danger of a steam explosion due to the contact between the cooling water and the molten metal as in the related art, and the safety of the operation of preparing the molten metal A and supplying hot water can be improved. .

Further, when the service life of the induction coil 9 or the like has reached the end of its service life and it becomes necessary to replace it, the crucible 3 is taken out of the furnace main body 2 and then the inner case 6 may be replaced with a new one. The work can be done easily.

[0020]

As described above, according to the present invention, the crucible is housed inside the furnace body provided with the melt-blocking layer on the inner periphery, with a gap provided between the melt-blocking layer and the crucible. If the crucible cracks and the molten metal leaks out of the crucible,
The molten metal can pass through the gap, travel along the outer surface of the crucible, take out the molten metal to the outside of the furnace main body, and embed an induction coil in the refractory layer of the furnace main body.
Covered with antioxidant, heat-resistant insulating material is wrapped around it, and the outside is coated with a melting barrier, so that even if molten metal leaks from the crucible, contact of the molten metal with the induction coil can be prevented. Thus, there is no danger of a steam explosion due to the contact between the cooling water and the molten metal as in the related art, and the safety of the operation of preparing and supplying the molten metal is improved.

When the molten metal leaks from the crucible, the molten metal can be taken out of the furnace main body, so that the molten metal can be detected by the molten metal leak detecting means and an alarm can be issued, and the crucible can be prevented from leaking. Immediately, the occurrence of an accident can be prevented.

Further, since the furnace body is of a cartridge type in which the inner case can be replaced with the outer case, the replacement operation of the inner case can be easily performed.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view of a melting and holding furnace.

FIG. 2 is an enlarged longitudinal sectional front view of an induction coil portion of a melting and holding furnace.

[Explanation of symbols]

 2 Furnace body 3 Crucible 4 Lid member 5 Outer case 6 Inner case 7 Outer wall 8 Fireproof layer 9 Induction coil 10 Gap 11 Drain outlet 12 Drain chute 13 Detection sensor 14 Antioxidant 15 Heat resistant insulator 16 Heat resistant caster 18 Melting barrier layer A molten metal

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H05B 6/24 H05B 6/24 F term (Reference) 3K059 AA08 AB07 AB16 AB28 AC65 AC76 AD10 AD35 AD40 CD44 CD52 CD77 4K046 AA07 BA02 CB15 CD02 CD12 4K063 AA04 AA12 BA03 CA02 CA05 FA34 FA39 FA46

Claims (4)

[Claims] 1. A crucible is housed inside a furnace body provided with a refractory layer on an inner periphery thereof with a gap provided between the refractory layer and the crucible.
A melting and holding furnace in which an induction coil is buried in a refractory layer of the furnace body, the induction coil is covered with an antioxidant, a heat-resistant insulator is wound therearound, and the outside is coated with a heat-resistant caster. . 2. The melting and holding furnace according to claim 1, wherein the induction coil is formed using a heat-resistant material having a low electric resistance, such as nickel or inconel. 3. The melting and holding furnace according to claim 1, wherein the induction coil is of a cartridge type that can be replaced with a refractory layer of the furnace main body. 4. The melting and holding furnace according to claim 1, wherein a refractory melting barrier layer for covering the buried induction coil is provided on an inner peripheral surface of the crucible.