JPS611453A - Method and equipment for continuous casting - Google Patents

Abstract

PURPOSE:To improve the trasverse dimensional accuracy of a strip without strip crack by dividing transversely the pouring part of a casting mold to a plurality, making the liquid level of the molten metal to be poured into the specific divided part of the mold higher than the liquid level in the other divided parts and producing continuously the strip. CONSTITUTION:Two sets of intermediate partition plates 2c parallel with side seals 2b are fixed to the inside of a gate flask 2 to form chambers 9a-9c. The depth side of the plate 2c is made smaller than the depth size of the side seals 2b. The chambers 9a-9c are communicated with each other via the space 10 in the lower part of the plate 2c. Three pieces of nozzles 11a-11c are provided to a tundish 3 so as to supply separately the molten steel to the chambers 9a-9c of the flask 2. The nozzles 11b, 11c on both sides are made longer than the middle nozzle 11a. The liquid level h1 of the molten metal in the chamber 9a is made higher than the liquid level h2 of the chambers 9b, 9c when the molten steel is poured from the tundish 3 via the nozzles into the chambers 9a-9c.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a continuous casting method and an apparatus therefor that prevent plate breakage or plate cracking and achieve uniform plate thickness distribution.

[Conventional technology]

There are various types of equipment for continuously casting strips, such as twin roll type, heald type, and caterpillar type.
For example, a twin-roll continuous casting apparatus is shown in FIGS. 1 and 2. In the figure (11 is a pair of left and right horizontal rolls, (
2) is a crusher, and (3) is a tundish that supplies molten steel (4) to crusher (2).
α) and a side seal (2b).

The molten steel (4) supplied from the R/Dino/U (3) to the crusher (2) rotates in the direction of arrow
A solidified shell (51) is formed from the surface side of 11, and the solidified shell (5) gradually grows and is pulled out from the roll gap (6) downward to cast a strip (7).

[Problem that the invention seeks to solve]

However, in the conventional apparatus described above, the molten H(4) is cooled faster on the side seal (2b) than the center and its temperature drops, so the semi-solidified material ( 8) grows abnormally, and the semi-solidified product (
8) falls off and gets caught in the roll gap (6).

If the semi-solidified material (8) is rolled into the roll gap (6), there is a risk that the plate will break or crack during casting.

Furthermore, as the semi-solidified material (8) is rolled into the roll gap (6) and kinked, unevenness may occur on the surface of the strip, which may result in uneven thickness distribution of the product.

In view of the above-mentioned circumstances, it is an object of the present invention to provide a continuous casting method and apparatus that can prevent plate breaks and plate cracks from occurring during casting and can obtain products with uniform plate thickness distribution. This is what I did.

[Failure to solve the problem]

In the present invention, the mold pouring part is divided into a plurality of parts in the width direction,
It has a configuration in which the liquid level of the molten metal poured into a predetermined mold division is made different from the liquid level of the molten metal poured into other mold divisions. Embodiments of the invention will be described with reference to the accompanying drawings.

FIGS. 3 to 8 show an embodiment of the present invention, in which crushing (2)
Inside, two sets of intermediate partition plates (2G) parallel to the side seals (26) are fixed, and the chambers (9α) (96) (9c
) is formed. The depth direction dimension H of the intermediate partition plate (2c) is smaller than the depth direction dimension H2 of the side seal (2b), and each chamber (9a) (96) (9c) is a lower space part of the intermediate partition plate (2G). 00).

In Tampuiso/Yu (3), each chamber (9α) in crushing (2)
) (9b) so that molten steel can be separately supplied to (9,),
3 nozzles/L, <11a) (11b) (11c
), and the nozzles # (11b) and (11c) on both sides are longer than the nozzle (Iiα) in the middle. In the drawings, the same reference numerals as those shown in FIGS. 1 and 2 indicate the same components.

When casting, remove the nozzle (H) from the tundish (3).
a) Molten steel is poured into the chambers (9α bar 9b) (9c) of crushing (2) via (11b) and (11c), but in this case, the liquid level of the molten steel supplied to the chamber (9α) Saoi room (9)
b) If the liquid level height of the molten steel supplied in (9c) is h2, make sure that hl>h2. This is because the inventors conducted various experiments and found the following.

That is, as shown in FIG. 8, the heat transfer coefficient α (W
/m2°C) and the contact time t (sgc,) between the molten steel and the horizontal roll is plotted on the horizontal axis.If the static pressure p (Kr) is changed from small to large, the heat transfer coefficient α and the contact time The relationship with t changes as shown in curves (a), (b), and (c); for the same contact time, the smaller the static pressure is, the smaller the heat transfer coefficient α becomes. Therefore, if the height h2 of the molten steel in chambers (9b) and (9c) is lowered, horizontal roll (1) and solidified shell (5
) becomes smaller, making it difficult for the molten steel to be cooled, thereby preventing abnormal growth of semi-solid material above the roll gap (6) on the inner surface of the side/rule (2b).

The molten steel poured into each chamber (9α) C9b) (9c) of the crushing (2) is cooled by the horizontal roll (1), and a solidified shell (5) is formed by the force on the surface of the horizontal roll (1). ,
The solidified shell (5) gradually grows until the roll gap (
6) is pulled downward and the strip plate (7) is cast.
As mentioned above, since there is no abnormal growth of semi-solidified material and no falling of the semi-solid material into the roll gap (6), there is no occurrence of plate breakage or plate cracking during casting, and the thickness distribution of the strip becomes uniform.

In the embodiments of the present invention, the case of casting steel has been described, but the present invention can be applied to the casting of various metals other than steel, and the number of crushing chambers can be any number as long as there is a plurality of chambers. Of course, various changes may be made without departing from the gist of the invention.

〔Effect of the invention〕

According to the continuous casting method and apparatus of the present invention, plate breakage and plate cracking do not occur during casting, so there is no fear of line stoppage, production efficiency is improved, and plate thickness distribution can be made uniform. Therefore, various excellent effects such as improved product quality can be achieved.

4. Brief explanation of aspects Figure 1 is an explanatory diagram of the conventional device, Figure 2 is a plan view of Figure 1,
Figure 3 is an explanatory diagram of the continuous casting method and apparatus of the present invention;
The figure is a view taken in the direction of arrows ■-■ in FIG. 6, FIG. 5 is a perspective view for explaining the crushing used in the present invention, FIG. 5 and 8 are graphs showing how the heat transfer coefficient between the horizontal roll and the solidified shell changes depending on the contact time or static pressure between the molten steel and the horizontal roll.

Claims (1)

[Claims] 1) In a method of pouring molten metal into a mold and cooling it to continuously cast a strip, the mold pouring section is divided into a plurality of sections in the width direction, and the molten metal is poured into predetermined mold division sections. A continuous method characterized in that the liquid level of the molten metal poured into the other mold divisions is made different from the liquid level of the molten metal poured into the other mold divisions, and the heat transfer coefficient between the solidified shell and the cooling mold is distributed in the plate width direction. Casting method. 2) In a device that pours molten metal into a mold, cools it, and continuously casts a strip, the mold pouring section is divided into multiple sections in the width direction, and a tandate nozzle is used to supply the molten metal to each mold pouring section. A continuous casting device characterized in that the length is shortened in the portion where the liquid level of the molten metal in the mold is high and lengthened in the portion where the liquid level of the molten metal in the mold is low.