JPH0823473B2 - Construction method of lower furnace body of groove type induction furnace - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for constructing a lower furnace body of a groove type induction furnace which is excellent in various properties such as corrosion resistance, heat resistance, penetration resistance and pressure resistance.

[0002]

2. Description of the Related Art As shown in the longitudinal sectional view of FIG. 3, in a groove type induction furnace, a primary coil 5 is put in a water-cooled bushing 6 at the center of the bottom of the furnace as a heat source, and the primary coil 5 is placed in a refractory material 10.
Which is arranged so as to cover the inner surface of the primary coil 5 with an alternating current to generate an induced current in the molten metal 12 in the canal groove 11 on the outer periphery of the primary coil 5 to resistance-heat the molten metal 12. Is. The lower furnace body of the groove-type induction furnace refers to the peripheral portion of the canal groove 11 below the furnace body in which the primary coil 5 shown in FIG. 3 is arranged. In addition to being held in a fluidized state by the magnetic force, it is located in the lower part of the furnace body and is subjected to a large hydrostatic pressure.Therefore, the refractory material layer in this part has various corrosion resistance, heat resistance, penetration resistance, pressure resistance, etc. Characteristics are required. However, it is impossible to combine the above-mentioned various characteristics with one kind of refractory material. Therefore, the present inventors have previously proposed that the groove type induction furnace has a refractory structure with corrosion resistance on the side in contact with the molten metal. We have proposed a composite in-furnace refractory structure (hereinafter referred to as "composite refractory structure") in which an excellent refractory material is used, and a refractory material having excellent penetration resistance is used inside (refer to Japanese Patent Application No. 2-4662).
7).

By the way, as a refractory material for such a groove-type induction furnace, Al ₂ O ₃ or Al ₂ O ₃ is conventionally used as SiO _2, Cr.
A ramming material containing ₂ O _3, MgO _, SiC or the like is used. This ramming material is formed by directly impregnating the powdery refractory material in a dry state or by adding about 3% of water and moistening it in a layer at a predetermined position in the furnace, and then heat-curing this surface. It was made. Thus, the characteristics of this ramming material are that it can be easily applied to any irregular shape, and the inside of the ramming material layer after application is in a non-sintered state, which means that the ramming material undergoes a sharp Even with respect to thermal strain, the ramming material layer, unlike ordinary molded refractory materials, has no risk of penetration cracking, and therefore there is no risk of molten metal leaking out to the primary coil or outside the furnace. The inside of the ramming material layer is gradually sintered due to a temperature rise during use of the furnace and permeation of molten metal. By the way, if a composite refractory structure composed of layers of different refractory materials as described above is sequentially formed with an amorphous refractory, since the raw material of the irregular refractory is a powder, a mixed layer is inevitably formed at the boundary. However, it is difficult to separately provide each of them, so that the obtained composite refractory material layer cannot sufficiently exhibit the characteristics of the individual refractory materials.

[0004]

SUMMARY OF THE INVENTION The present invention has been made as a result of intensive studies in view of such a situation, and an object thereof is to provide a groove type excellent in various characteristics such as heat resistance and penetration resistance. It is intended to provide a method for constructing a lower furnace body of an induction furnace. That is, the present invention is a method for constructing a lower furnace body in which a primary coil of a groove-type induction furnace is arranged, and a refractory layer provided between a heat insulating material layer of the lower furnace body and a water-cooled bushing for protecting the primary coil. Is divided into two layers, a core layer that is in contact with molten metal and a backup layer that supports the core layer from the inside. First, as the core layer, a molded refractory formed into a predetermined shape is provided in front of each of the heat insulating material layer and the water cooling bushing. In this case, a backup layer is formed by arranging a predetermined gap in each of the above and then filling each of the gaps with an unshaped refractory made of a ramming material.

The furnace construction method of the present invention will be specifically described below with reference to the drawings. FIG. 1 is an enlarged explanatory view of a lower furnace body showing an example of a method of constructing a furnace according to the present invention. A heat insulating brick is piled up inside the iron shell 1 forming the outer circumference of the groove type induction furnace to form a heat insulating layer 2, and a predetermined gap is provided between the heat insulating layer 2 and the water cooling bushing 6 for protecting the primary coil 5. Open 4 and 14,
The core layers 3 and 13 which have been formed in a predetermined shape are respectively arranged (Fig. A), and then the respective gaps 4 and 14 are filled with an amorphous refractory material to form the backup layers 7 and 17 (Fig. B). Here, in order to manufacture the core layers 3 and 13, the canal groove-shaped wooden core 9 is formed in the molds 8 and 18 made of an iron plate as shown in FIG. Place the gap 24,34
Generally, a method of filling and molding a refractory material to form a core layer into a tubular core layer is used, but in addition to this method, slip casting is used without using a core and the canal groove is used. Any method such as a method of integrally molding the shell portion of the above, or a method of forming a deformed brick with holes and combining the bricks in a spine shape to mold the shell can be applied. In the method of the present invention, the refractory used as the core layer is made of castable cement or brick of SiC, SiN, MgO or the like having excellent corrosion resistance and heat resistance. For the backup layer provided inside the core layer, a ramming material such as Al ₂ O ₃ system or MgO system, which is suitable for the ramming method and has excellent penetration resistance and pressure resistance, is used. In the method of the present invention,
Since a castable or brick shaped refractory is used for the core layer in contact with the molten metal, unlike the conventional method in which a ramming material is used for the entire refractory layer, at least the core layer is an excellent material regardless of the suitability of the ramming method. Has the advantage that it can be widely selected in terms of characteristics.

[0006]

In the method of the present invention, the refractory layer provided on the heat insulating layer of the lower furnace body or on the water-cooled bushing for protecting the primary coil supports the core layer in contact with the molten metal and the core layer from the inside. The backup layer is divided into two layers, first, the core layer is formed as a molded refractory having a predetermined shape, and a predetermined gap is provided between the heat insulating material layer and the water-cooling bushing. Since the backup layer is formed by filling the irregular-shaped refractory, the core layer and the backup layer are formed independently of each other and do not mix with each other. The entire material layer has excellent properties.

[0007]

The present invention will be described below in detail with reference to examples. Example 1 A groove type induction furnace having the same structure as shown in FIG. 1 was produced. First, two layers of heat insulating bricks having a thickness of 30 mm are spread inside the iron shell 1 to form a heat insulating layer 2. Between the heat insulating layer 2 and the water cooling bushing 6 for protecting the primary coil, the heat insulating layer 2 to 200 mm,
Two core layers 3 and 13 formed in a predetermined shape are respectively arranged at intervals of 100 mm from the water-cooled bushing 6, and then the backup layers 7 and 17 of the amorphous refractory are placed in the gaps 4 and 14, respectively. Were filled in each to construct a furnace. In the above, various refractory materials having excellent corrosion resistance and heat resistance are used for the molded refractory of the core layer, and various refractory materials having excellent penetration resistance and pressure resistance (ramming are used for the irregular refractory of the backup layer. Material) was used. Also, the molding refractory of the core layer is
It was prepared by the same method as shown in FIG.

Example 2 A furnace was constructed in the same manner as in Example 1 except that the core layer was formed by combining perforated bricks in the shape of a backbone.

Comparative Example 1 A furnace was constructed in the same manner as in Example 1 except that the backup layer of the refractory material layer and the core layer of the lower furnace body were sequentially formed of the ramming material. Using each of the thus obtained groove-type induction furnaces, the molten metal of the Cu—Mg alloy having a strong erosion reaction was held for a long time, and the clogging degree of the canal groove of the lower furnace body was investigated. The results are shown in Table 1.

[0010]

[Table 1]

As is clear from Table 1, the method product of the present invention
(No.1,2,5 ~ 9), the refractory material layer is divided into two layers, the core layer in contact with the molten metal is made of molded refractory, and the backup layer is made of ramming material. The layers did not mix with each other, and therefore the characteristics such as the corrosion resistance inherent to the core layer were sufficiently exhibited, and clogging of the canal groove could be prevented for a long time. Further, the backup layer also exhibited excellent properties such as penetration resistance, and no accident such as leakage of molten metal occurred.
Further, since the ramming material used had an appropriate sintering temperature, it was satisfactorily sintered depending on the temperature of the furnace body in use. On the other hand, in the comparative method products (Nos. 12 to 13), the backup layer and the core layer were all formed of the ramming material, so that both layers were mixed at the boundary part and each characteristic was impeded, and the core layer was resistant to The erosion property decreased and the canal groove began to be clogged early, and the permeation resistance decreased in the backup layer, and the exudation of molten metal was considerably observed.

[0012]

As described above, according to the method of the present invention, since the refractory materials forming the composite refractory material layer of the lower furnace body of the groove type induction furnace do not mix with each other, the characteristics of the refractory materials are different from each other. Sufficiently manifested, the life of the furnace is extended, and a remarkable effect is industrially achieved.

[Brief description of drawings]

FIG. 1 is a process explanatory view showing an example of an aspect of a furnace construction method of the present invention.

FIG. 2 is an explanatory diagram showing an example of a method of producing a core layer.

FIG. 3 is a vertical cross-sectional view of a groove type induction furnace.

[Explanation of symbols]

 1 Iron skin 2 Thermal insulation layer 3,13 Core layer 4,14,24,34 Gap 5 Primary coil 6 Water cooling bushing 7,17 Backup layer 8,18 Formwork 9 Wooden core 10 Refractory material 11 Canal groove 12 Molten metal

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shozo Sakamoto 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (72) Inventor Katsuhiro Tabata 9-4 Yamate, Ako-shi, Hyogo (72) Inventor Yoshitaka Ishihara 608-48, Fukumoto, Oku-cho, Oku-gun, Okayama (56) References JP 61-173074 (JP, A) JP 58-11555 (JP, B2) JP 61-29038 (JP, JP) Y2)

Claims (1)

[Claims] 1. A method of constructing a lower furnace body in which a primary coil of a groove type induction furnace is arranged, wherein a refractory layer provided between a heat insulating material layer of the lower furnace body and a water-cooled bushing for protecting the primary coil is provided. , A core layer that is in contact with the molten metal and a backup layer that supports the core layer from the inside are divided into two layers. First, as the core layer, a molded refractory formed in a predetermined shape is provided in front of each of the heat insulating material layer and the water cooling bushing. Place each with a predetermined gap, and then insert a ramming material into each gap .
A method for constructing a lower furnace body of a groove-type induction furnace, characterized in that a backup layer is formed by filling an amorphous refractory material.