JPH0415410Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] The present invention relates to a casting structure used in producing an ingot by electroslag remelting (hereinafter simply referred to as ESR). [Prior art and its problems] The ESR method is a method in which a consumable electrode is melted by the joule heat of a molten flux in the atmosphere or under an inert gas, and then solidified in a water-cooled copper mold. The oxides and sulfides in the molten metal are absorbed into the flux and removed, resulting in a Fe-based, Ni, etc. alloy with few impurities. At the beginning of the conventional ESR method, as shown in the longitudinal cross-sectional view shown in Fig. 5, a mold 2 made of copper is placed on a stool 1 made of copper to form a box-shaped box with a bottom. A bottom plate 3 with a thickness of about 30 mm is placed in the center, and around the bottom plate 3, for example,
Pack NgO powder 4, etc., then put lathe chips 5 on top of the bottom plate 3, and with the consumable electrode 6 in contact with the lathe chips 5, fill the tip of the consumable electrode 6 with flux 7, and then Apply (+) voltage to 6.
When a (+) voltage is applied to the consumable electrode 6, the lathe chips 5 begin to melt due to Joule heat between the stool 1 on the (-) electrode side, this becomes a ignition source, and the flux 7 begins to melt, and then, Melting of the consumable electrode 6 begins due to the joule heat of the molten flux. However, the bottom plate 3 placed on the stool 1 is made of the same metal as the consumable electrode 6 in order to prevent the stool 1 from melting due to arcing when electricity is started, but the bottom plate 3 is distorted and the stool 1 Due to the depressions and the like, the adhesion between the bottom plate 3 and the stool 1 is poor, the contact area is small, and therefore the electrical conductivity is deteriorated. Due to this deterioration of the current flow between the bottom plate 3 and the stool 1, a bottom arc is generated in the part where the bottom plate 3 and the stool 1 are not in close contact even after the start of melting or after entering a steady state, and the ESR ingot is charged. As a result, side arcs occur in the thin part of the flux skin between the ingot and mold 2.
This causes deterioration of the ingot skin in the area where the arc occurs. Stool 1 and mold 2 will be damaged by melting. mold 2
Copper contamination of the ingot occurs due to copper mixed in from the melted parts. Furthermore, the power consumption rate deteriorates due to a decrease in melting power efficiency. Various problems arose. In addition,
The MgO powder 4 is for preventing the bottom of the ingot from being welded to the stool 1. [Means for solving the problem] The present invention was made to solve the above-mentioned problem, and its feature is that it is a mold for ESR in which a conductive plate with a bottom plate in the center is placed on a stool. It's in the structure. Hereinafter, the mold structure of the present invention will be explained in detail. It is important that the conductive plate that constitutes this invention adheres well to the stool, and is designed to improve the conductivity of the current that flows through the consumable electrode, molten flux, ingot, bottom plate, and stool in this order. is 0.5
-5 mm is preferable; if it is less than 0.5 mm, the contact with the stool improves, but there is a possibility that it will be melted and damaged in a short time when electricity is applied. Further, if the thickness is 5 mm or more, melting loss due to current flow will not occur, but on the other hand, contact with the stool will deteriorate. This conductive plate may be made of a material that does not substantially change the alloy composition during ingot processing, and preferably, by selecting the same material as the ingot composition, even if it is partially melted, There is no fear of conventional problems such as copper contamination of the lump. Furthermore, the reason why the bottom plate is provided in the center of the conductive plate is to guide the current from the consumable electrode to the stool through the bottom plate, and this bottom plate is thicker than the conductive plate to prevent the bottom plate from melting away. 0.5~5mm
If the conductive plate is used only and the bottom plate is not placed in the center, the stool will also melt at the same time as the center of the conductive plate melts, shortening the life of the stool, and the copper from the stool will dissolve and contaminate the bottom of the ingot. I will do it. The bottom plate is made of metal with a thickness of 20 to 50 mm, like the conventional bottom plate, and is preferably made of a material that does not change the ingot composition or the same material as the consumable electrode. 1 to 4 are longitudinal cross-sectional views showing embodiments of the present invention, and the same members as in FIG. 5 are given the same reference numerals. FIG. 1 shows a metal plate whose size is approximately the same as the outer circumference of a mold 2 when viewed from above, a hole into which the bottom plate 3 is fitted is formed in the center of the metal plate, and the bottom plate 3 is fitted into the hole and fixed by welding. A conductive plate 8a having the following was created. This is an example of a mold structure in which the conductive plate 8a is placed on a stool, then the mold 2 is placed on it, and the conductive plate 8a is sandwiched between the stool 1 and the mold 2.
In the example shown in FIG. 1, the periphery of the conductive plate 8a receives the weight of the mold 2, so that the conductive plate 8a and the stool 1 are in complete contact with each other. In FIG. 2, a conductive plate 8b having a bottom plate 3 in the center is created by using a metal plate whose size is almost equal to the outer circumference of the mold 2 in plan view, and placing the bottom plate 3 in the center and fixing it by welding. This is an example in which the conductive plate 8b is sandwiched between the stool 1 and the mold 2 as shown in FIG. Compared to the example shown in FIG. 1, the conductive plate 8b can be easily manufactured in that a metal plate without a hole in the center is used. 3 shows a shape in which the outer periphery of the metal plate in the example in FIG. 1 fits closely inside the mold 2, and in FIG. 4, the metal plate in the example in FIG. It has a shape that fits closely inside the mold 2 as shown in FIG. The examples shown in Figures 1 and 2 have a structure in which the conductive plate and the stool are brought into close contact by the weight of the conductive plate itself and the weight of the mold, and the examples shown in Figures 3 and 4 have a structure in which the conductive plate is brought into close contact with the stool by the weight of the conductive plate itself and the weight of the mold. is brought into contact with the inner surface of the mold, and
The conductive plate is held tightly against the stool by its own weight. [Example] As an example of the present invention, a mold structure shown in FIG. 1 was used, and as a conventional example, an ingot was manufactured by the ESR method using a mold structure without a conductive plate as shown in FIG. Table 1 shows the ingot manufacturing conditions, and Table 2 shows the results.

【table】

【table】

[Table] From the results in Table 2, the present invention improves the conductivity to the stool compared to the conventional example, and reduces arcing in the middle of the ingot due to less charging in the molten flux area. Therefore, it can be seen that the surface roughness of the ingot is reduced and the area ratio to be repaired is also reduced by 20%, the number of mold repairs is reduced to 1/3 of that of the conventional method, and the electricity consumption rate is also improved. . In this example, copper contamination of the ingot was not analyzed. [Effects of the invention] The present invention has a simple structure in which a conductive plate with a bottom plate in the center is placed on a stool in the mold structure used when manufacturing ingots by ESR. This has many great effects, such as improving the surface quality of the ingot, extending the life of the mold, and lowering the power consumption. Note that the casting structure of the present invention is applicable to all types of ESR, such as a fixed mold type, an ingot pulling type, a moving mold type, and a multi-electrode type.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing the mold structure of the present invention;
FIG. 2, FIG. 3, and FIG. 4 are longitudinal sectional views showing other ingot structures of the present invention, and FIG. 5 is longitudinal sectional views showing a mold structure in a conventional example. 1... Stool, 2... Mold, 3... Bottom plate, 6... Consumable electrode, 8a, 8b... Conductive plate.

Claims (1)

[Scope of utility model registration request] 1. A mold structure for electroslag remelting, which is used for manufacturing an ingot by electroslag remelting, characterized in that a conductive plate having a bottom plate in the center is placed on a stool.