Specialized metallurgical processes – compositions for use therei – Processes – Electrothermic processes
Patent
1992-11-20
1995-07-04
Kastler, Scott
Specialized metallurgical processes, compositions for use therei
Processes
Electrothermic processes
266234, 266237, 266275, B22D 41005
Patent
active
054296552
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a system for removing non-metallic foreign matter in a molten metal, which includes a tundish, an electromagnetic coil for generating a shifting field, a moving apparatus therefor, and an operation method, in steel continuous casting facilities and so forth.
BACKGROUND ART
In a production technology for high quality sheets, removal of non-metallic foreign matter or impurity during the molten steel state is critical for determining fraction defective of the products. It is recent trend in molten steel purification technologies, ladle and a mold in a continuous casting to prolong a period to maintain the molten steel in the tundish with the expected floating up of the foreign matter; route of the molten steel to prolong period to maintain the molten steel in the tundish; and a discharge opening of a nozzle from penetrating by modifying configuration of an immersion nozzle to control flow of the molten steel within the mold.
However, with these methods, satisfactory improvement of the quality cannot be obtained. Particularly, the quality at the non-steady pouring, so-called as ladle exchange, is a level creating a problem. Therefore, methods are disclosed in Japanese Unexamined Patent Publications (Kokai) Nos. 58-22317, 55-107743, 01-312024 and 02-217430, to generate a horizontal swirl flow of the molten metal to float up the foreign matter. This technology provides centrifugal force by horizontal rotation to the molten metal and the non-metallic foreign matter so as to concentrate the non-metallic foreign matter toward the swirl center due to difference of specific weights to separate by promoting collision, absorption and aggregation. This technology can achieve an improvement in the foreign matter separation effect in comparison with the methods simply prolonging dwell period or controlling molten steel flow path in the tundish. In other words, when an equal separation capacity is required, the last-mentioned method may provide an advantage in significant reduction of the size of the tundish.
On the other hand, the technology disclosed in Japanese Unexamined Patent Publication No. 58-22317 simply provides a rotational force generating apparatus outside of the tundish. On the other hand, the technologies disclosed in Japanese Unexamined Patent Publications Nos. 55-107743, 01-312024 or 02-217430, simply provide energization coils in the outer circumferences of the tundishes, and do not disclose concrete facility construction. Accordingly, if such technologies are applied, a problem is encountered in restriction for attaching and detaching power source cables, cooling water paths upon moving the tundish for the repairing or so forth, the magnitude of movement of which can be substantial, because the rotational force generating apparatus or the energization coil have to be moved therewith.
Especially, in case of the apparatus for electromagnetically providing rotational force (energization coil), connection of the cable is a labor intensive operation, and the operation is very difficult. On the other hand, they may provide an advantage to permit preliminary adjustment of positional relationship between the tundish and the coil. However, the above-mentioned problem is much more critical.
On the other hand, the above-mentioned method for purifying the molten steel employing horizontal swirl flow as disclosed in Japanese Unexamined Patent Publications 58-22317 or 55-107743, the following problems can be encountered. circumferential portion of the molten steel proturburates in parabolic fashion, the height of which is proportional to square of the radius and rotation speed Therefore, increasing of the radius results in substantial increase of the height of the facility. In addition, in order to drive all of the molten steel for horizontal rotation, substantially large electromagnetic coil is required which increases cost for the facility making it impractical. requirements for the facility. However, reduction of the capacity Of the tundish may make it imp
REFERENCES:
patent: 3709476 (1973-01-01), Hammarlund et al.
patent: 5106411 (1992-04-01), Miki et al.
Kitaoka Hidenari
Miki Yuji
Moriwaki Saburo
Nabeshima Yuki
Ogura Shigeru
Kastler Scott
Kawasaki Steel Corporation
Miller Austin R.
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