JPH08219659A - Induction furnace lining refractory construction method - Google Patents

Abstract

(57) [Summary] [Purpose] In view of the short life due to the cracking of the lining fireproof wall of the induction furnace, the object is to provide a method of providing a lining material with a long life. [Structure] A vertical or lower wide partition frame 6 is installed so that the lining refractory has a two-layer structure of an operating layer 2 and a non-operating layer 5 within a predetermined thickness, and refractory materials of different materials are put into both of them. After that, after the partition frame 6 is pulled out, the innermost frame is subjected to filling and filling while vibrating, and construction is performed. [Effect] There are few cracks in the construction body and the development is small,
Due to the high degree of sintering of the working layer and its high corrosion resistance, the service life is greatly extended, and the uncured material of the non-working layer uses a refractory material that is cheaper than the material used in the conventional method. It is possible and its effect is tremendous.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a furnace wall lining material for an induction furnace used for melting metal.

[0002]

2. Description of the Related Art Melting of metals in the casting industry is
Due to problems such as labor saving, quality of molten metal, and working environment, etc. Little dissolution loss. 2. Easy to work and operate and easy to save labor. 3. There are few pollution problems. 4. A molten metal with high quality, stability and homogeneity can be easily obtained. 5. Easy adjustment of composition and temperature. The transition to induction furnaces, which have many advantages, is progressing rapidly. In the crucible type induction furnace, an electric induction heating coil is arranged on the outer periphery, and the coil surface is covered with coil cement to protect the coil if necessary, and a hot water sensor, an insulating material, a heat insulating material, etc. are arranged inside. It is constructed with a single refractory wall made of refractory inside. To construct this refractory wall, use an inner mold made of steel (hereinafter referred to as a former) designed to have a refractory wall with a specified thickness inside the furnace body, and place it in the gap between the furnace body and the former. While refractory is thrown in and vibration is applied from the inside of the former, the refractory thrown into this gap is filled and built. Higher skill is required because the quality of this dry powder material injection and vibration filling greatly influences the life of the furnace, and thus the operating rate of the foundry. In order to obtain a long life, the refractory used here is made of high-purity materials such as siliceous material, aluminous material, magnesia and / or spinel material, depending on the conditions of use, and if necessary sintering aids such as boric anhydride. However, due to the reaction dissolution loss with the melt and the generation and adhesion of an altered layer due to the penetration of the melt into the tissue, cracks and peeling from the surface layer occur, causing major damage. To be done. In this way, the glass material increases due to the formation of an altered layer due to the permeation of the melt into the structure and the heat received from the melt into the over-sintered state, which causes the volume to shrink, causing large cracks and groove-like formation. A stable furnace cannot be operated due to the creation of a melted state, and the metal insertion phenomenon occurs at the abnormal portion and the life is short, so the reaction melt loss is small and the groove-shaped melt loss due to the occurrence of cracks The current situation is that there is a strong demand for fireproof walls that are free of damage and ingots.

[0003]

At present, the lining refractory wall of the induction furnace is an integral refractory wall which is mainly vibrated by dry powder, and this refractory wall permeates foreign substances into the tissue during use and is deteriorated by heat reception. A crack is generated with the formation of a layer and shrinkage of the volume, and the insertion of the metal is the life of the fire wall due to the crack. Due to such abnormal damage, the refractory wall material cannot be fully used, and the life of the refractory wall remains 60% to 80%, and replacement with a new material is unavoidable. It is a technical subject to provide a method of eliminating these defects and providing a lining material that can measure the long life.

[0004]

In view of such a situation, the present inventors have found that the effective utilization rate of a fire wall is about 60% (11
0mm fire wall up to a maximum of 60mm).
If further damage occurs, the overcurrent value will occur and normal operation will not be possible. The refractory within this range should be a uniform and densely packed work body to have a long life, and the outer layer of the fire wall is weaker than the inner layer but should not be solidified and should not be cracked or abnormally melted. The life of the furnace will be improved by suppressing the intrusion of molten metal on the spot and keeping it in the state that the furnace body, that is, the range where the hot water sensor does not operate, is filled with the characteristics of the refractory to be used so that the refractory can be fully utilized. Paying attention to the fact that it can be raised, the working layer in the furnace is operated by placing a high corrosion resistant material with high sinterability by receiving the heat of the molten metal and a refractory that does not solidify below 1000 ° in the non-operating layer. Even if cracks occur in the layers and ingots enter, a multilayer structure that can stop the infiltration of further molten metal by the unburned solid layer enables more stable furnace operation and finds a long service life. I was able to do it. How to construct this multi-layered wall As a result of various studies, in order to construct the refractory material with a predetermined thickness within the thickness of the side walls to be multi-layered, a partitioning frame is arranged in a predetermined thickness layer and both After putting different refractory materials into each of them, pull out the partition frame while keeping the same or applying vibration. 2
The two-layer fire wall is constructed by the vibration method while applying the vibration to the innermost frame of the conventional two-layer fire wall that the fireproof materials of the materials are in contact with each other. The construction of the partition frame could be done easily, and in this case, the shape of the partition frame for the refractory material of different materials is vertical or wide, and the inclination is about 1/100, which is the best workability. The reason for limiting is that the shape of the formwork is from vertical to downward wide, and the inclination is 0 to
1/100 is because the mold can be pulled out after the refractory material is put into it. In the case of widening, the refractory material put into the frame will be lifted up together when the mold is pulled out. Sufficient refractory material cannot be placed. Further, even if the width is lower, if the inclination gradient is large, the mold cannot be pulled out.

[0005]

The details of the present invention will be described by way of examples. Table 1 shows the quality of the refractory materials used in the examples of the present invention, Table 2 shows the mixing ratios and quality characteristics of the examples and the conventional refractory materials, and examples of construction are shown in FIGS. 1 and 2.

[0006]

[Table 1]

[0007]

[Table 2]

[0008]

Example 1 As a method of constructing a refractory lining for a 3 ton type low frequency induction furnace, as shown in FIG. As shown in Fig. 1, 6
Like the above, the inner frame (former) 1 and the partition frame 6 are set so that the non-operating layer has a thickness of 50 mm and the operating layer has a thickness of 60 mm, and the uncured material 5 is in the non-operating layer and the high corrosion resistance material is in the operating layer side. After 2 was charged, the partition frame 6 was pulled out, and after vibrating and filling, the inner frame (former) 1 was removed, and the state of FIGS. At the same time, it was compared with the conventional product constructed by the method shown in FIGS. The normal use temperature was 1530 ° C., and ductile cast iron was used as the melting material. Table 3 shows the results. Since Example 1 is a two-layer wall construction using a siliceous material, the high corrosion resistance material 2 that is the working layer of the embodiment of the present invention and the conventional product are the same refractory material, but the non-working layer is the non-hardened material. 5
Therefore, the powder is kept in a powder state, and the metal that stops due to the crack of the working layer stops at the joint between the high corrosion resistance material 2 and the powdered hardened material 5, and the service life is more stable than that of the conventional method. The amount of erosion loss per charge in a groove crack due to the development of a crack to be determined is 0.198 mm in the case of the construction method according to the present invention and 0.396 mm in the case of the conventional method, which is 59.6%. .

[0009]

[Table 3]

[0010]

[Example 2] As Example 2 of the present invention, a zircon-siliceous material was used as a highly corrosion-resistant material which is an operating layer, and a natural silica stone material was used as an end-hardening material in the non-operating layer as in Example 1.
Construction was carried out as a lining refractory of a 3TON induction furnace by the same method as in Example 1, and a practical test was performed in the same manner as in Example 1 and compared with the conventional method. The results are shown in Table 4. The state of the operating surface of the refractory lining of the induction furnace built by the construction method of the present invention is smooth and stable, whereas the construction body by the conventional method has many cracks, a high degree of development and a large groove shape. The maximum amount of erosion is 0.332m per charge per charge.
With respect to m, the construction body by the construction method of the product of the present invention was 0.131 mm per charge, which was about 31%, which was good.

[0011]

[Table 4]

[0012]

The construction of the refractory lining for the 3TON type low-frequency induction furnace according to the present invention is carried out within 93 minutes according to the conventional method.
Although it was 00 minutes, the construction time was slightly increased, but by constructing the inner wall refractory of the induction furnace with a two-layer material and performing simultaneous construction, the construction body has few cracks and little development, and the firing of the working layer is small. Due to the higher degree of bonding and the higher corrosion resistance, the construction method using the material of Example 1 uses 241 charges, and the zircon-siliceous material of Example 2 is used, compared with the durability of 185 charges of the conventional method. With the construction method according to the existing construction method, the 471 charge and durability are greatly extended, and for the uncured material of the non-operating layer, it is possible to use a refractory material that is cheaper than the material used in the conventional method, and its effect is great. It is a thing.

[Brief description of drawings]

1A, 1B and 1C are explanatory views of a construction method of the present invention.

2A and 2B are explanatory views of a conventional construction method.

[Explanation of symbols]

 1 Inner frame (former) 2 High corrosion resistance material (operating layer) 3 Insulation material 4 Insulating material 5 Unhardened material (non-operating layer) 6 Partition frame 7 Vibrator

Claims (1)

[Claims] In the construction of refractory lining of induction furnace that melts metal,
The refractory lining is either vertical or wide (inclination is 0% to 1/10) so as to have a two-layer structure of an operating layer and a non-operating layer within a predetermined thickness.
0) Install a partition frame, put refractories of different materials into both, then pull out the partition frame as it is or with vibration, and then add and fill while applying vibration to the innermost frame. A method for constructing a refractory lining for an induction furnace, characterized by: