Metal founding – Process – With measuring – testing – inspecting – or condition determination
Patent
1997-06-18
2000-08-15
Batten, Jr., J. Reed
Metal founding
Process
With measuring, testing, inspecting, or condition determination
1641541, 1641545, 1641548, 164417, 164476, B22D 11128, B22D 1120
Patent
active
061021016
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a continuous casting method and an apparatus therefor in which a cast slab is continuously withdrawn from a mold, and more particularly one in which a cast slab having a liquid core is subjected to reduction so as to produce a thin cast slab.
BACKGROUND ART
A typical method of producing a thin plate includes rolling and forming in a rolling step. In this type of method, it is necessary before application of hot rolling to reheat a cast slab which has once cooled after casting. This process is disadvantageous from the viewpoint of energy consumption.
Recently, a direct hot rolling method has been under development. According to the direct hot rolling method, a cast slab obtained from a continuous casting machine is directly supplied to a rolling mill. Particularly, many attempts have been made to develop a continuous casting method which can produce cast slabs with rough hot rolling being omitted in the direct hot rolling process.
As a method of producing a thin cast slab, there has been proposed a method comprising continuously withdrawing a cast slab out of the mold, reducing the thickness of the cast slab using a plurality of pairs of reduction rolls while it has a liquid core, and cooling the resulting slab. This method is referred to as the liquid core reduction method.
Japanese Patent Publication No. 6-28790/1994 discloses a method of reducing the thickness of cast slabs having a liquid core with pairs of reduction rolls. According to this method, a series of spacers each having a different thickness are inserted between each pair of rolls to produce a cast slab having a target thickness by means of an arrangement in which the thickness of spacers gradually increases for downstream pairs of rolls and the roll gaps between the pair of rolls gradually decrease for downstream pairs of rolls. Cast slabs are subjected to a reduction force corresponding to roll gaps in each of which spacers are inserted. In addition, Japanese Patent Publication No. 6-28789/1994 discloses a method of carrying out casting by applying to each pair of rolls a reduction force which is increased depending on the time required until an unsolidified cast slab withdrawn from a mold reaches respective reduction rolls so that a given amount of roll reduction may be applied to the cast slab before finishing the roll reduction.
SUMMARY OF THE INVENTION
According to the prior art method disclosed in Japanese Patent Publication No. 6-28790/1994, however, a roll gap, which determines the thickness of cast slabs, is determined by spacers, and many spacers must be stored in order to produce a wide variety of thickness of slabs. Spacers must be changed every time the thickness of cast slab is changed. Thus, this method is not practical. In addition, since the reaction force of the roll reduction is not considered, a problem of variation with respect to thickness of cast slabs is inevitable.
On the other hand, since cast slabs have different densities depending on their steel types, a reaction force is also varied. According to the prior art method disclosed in Japanese Patent Publication No. 6-28789/1994, the reduction force is determined by a time interval until a cast slab withdrawn from a mold reaches a reduction roll. Thus, there is a problem that variation in the thickness of cast slabs, which is caused by a change of the reaction force to each of the reduction rolls, cannot be entirely prevented.
In addition, in either method, reduction of roll gaps is described, but there is no description of the case where the roll gap is increased. The amount of strains introduced in the solidification interface during roll reduction of cast slabs having a liquid core is determined depending on the amount of reduction of the liquid core, but not on the reduction speed of the reduction rolls. Thus, however much the reduction speed is increased, there is no internal cracking occurring during roll reduction of a liquid core until a target reduction of the liquid core is achieved as long as the targ
REFERENCES:
patent: 5488987 (1996-02-01), DiGiusto et al.
patent: 5577548 (1996-11-01), Hohenbichler et al.
Hanazaki Kazuharu
Koide Masakazu
Kumakura Seiji
Murakami Toshihiko
Oka Masahiko
Batten, Jr. J. Reed
Sumitomo Metal Industries Ltd.
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