Metal founding – Process – Shaping liquid metal against a forming surface
Patent
1996-11-21
2000-02-15
Batten, Jr., J. Reed
Metal founding
Process
Shaping liquid metal against a forming surface
164459, B22D 1104, B22D 1107
Patent
active
060241624
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a continuous casting method for a square having less rhomboidity deformation or a round billet having side periphery deformation and to a casting mold used for the method.
BACKGROUND ART
To continuously cast a billet, a molten steel 51 is charged into a casting mold 50, having a substantially square inner section and oscillating up and below from a tundish above the casting mold as shown in FIG. 18, and a solidified shell 52 is formed on the inner surface of the casting mold while heat is absorbed from the side surface of the casting mold 50 which is cooled with water. The solidified shell 52 is then drawn out gradually, and the molten steel 51 at a core portion, too, is gradually solidified so as to form a billet.
To accomplish lubrication between the inner surface of the casting mold and the solidified shell 52, rape seed oil (an example of the lubricant) is charged little by little from above the casting mold 50, and is then carbonized to obtain a lubricant.
However, when casting of the billet is carried out at a high speed (at 3 m/min, for example), a difference in solidification shrinkage occurs because the gap between the solidified shell 52 around the four outer periphery surfaces of the billet and the casting mold 50 is not uniform, and the section of the product becomes a rhomboid. In a round billet, side periphery deformation such as an oval section of the product or the occurrence of a recess takes place. For this reason, the continuous casting method of the billet according to the prior art has been carried out within an allowable speed range in which this rhomboidity, i.e. rhomboid deformation, does not occur, and the problems of a relatively low speed of the casting speed and low productivity are yet left unsolved.
In the case of continuous casting of slabs having a rectangular section, on the other hand, Japanese Examined Patent Publication (Kokoku) No. 57-11735 proposes a casting mold for continuous casting which is directed to prevent longitudinal cracks of a slab and damage such as slag bite by disposing uniformly a large number of recesses having a width or diameter of not greater than 2.5 mm at a part of the inner surface or the whole inner surface of the casting mold. It has been found out that when this technology is applied to continuous casting of billets, the recessed portions are gradually filled with carbon powder as the lubricant because the diameter of the recessed portions is not greater than 2.5 mm, and stable casting cannot be conducted.
SUMMARY OF THE INVENTION
In view of the technical background described above, the present invention is directed to provide a continuous casting method, for a billet, capable of conducting stable casting at a high speed without causing rhomboidity in the billet produced by continuous casting, and a casting mold used for this method. The gists of the invention are as follows.
(1) A continuous casting method of a billet for effecting casting by charging a molten metal from the upper portion into a casting mold oscillating in a vertical direction characterized in that: a large number of dimples are formed on the four inner peripheral surfaces of the casting mold below, and within a distance of 200 mm from, the lowermost position of a meniscus under a steady operation state so as to make the cooling capacity of each inner surface of the casting mold substantially uniform.
(2) A continuous casting method for a billet for effecting casting by charging a molten metal from the upper portion into a casting mold oscillating in a vertical direction and by charging a small amount of a lubricant, characterized in that: large number of dimples are formed on the four inner peripheral surfaces of the casting mold below, and within a distance of 200 mm from, the lowermost position of a meniscus under a steady operation state, so as to make a cooling capacity of each inner surface of the casting mold substantial uniform.
(3) A casting mold oscillating in a vertical direction and having a substantially square inn
REFERENCES:
patent: 4250950 (1981-02-01), Buxmann et al.
Fujinaga Teruo
Nakao Kazutoki
Sato Toshiki
Uehara Masatsugu
Batten, Jr. J. Reed
Nippon Steel Corporation
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