JP2942471B2 - Mold for continuous casting machine for thin slab - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for a continuous casting machine for thin slabs. Thin slabs usually mean rectangular slabs with a thickness of less than 100 mm. Conventional ordinary continuous casting machines cast slabs with a thickness of 200 mm or more, but recently there is a tendency to directly cast thin slabs with a thickness of 100 mm or less. This is because the thinner the thinner the final product cannot be directly cast, the more the rolling step by the subsequent rolling mill can be omitted. However, various methods of casting a thin slab have been proposed for a long time. For example, a method in which a mold is a belt type (JP-A-4-15704)
No. 8, etc.) The mold is of a twin roll type (Japanese Patent Laid-Open No. Hei 3-2487).
No. 49) Rolling down (rolling) online after casting, that is, rolling down slabs by rolling down slabs with rolling rolls provided along the pass line below the mold, etc. There is. Of the above three examples, the term "and" means that the casting method is fundamentally different from that of a continuous casting machine using a normal through-hole (without bottom) mold. Since a reduction amount adjusting device is required, the equipment becomes complicated and expensive, and in this respect, there is not much difference from the apparatus in which the casting is performed and the final product is rolled by the rolling equipment of another line.

[0002] The present invention relates to a continuous casting machine that can cast thin slab slabs directly, that is, without rolling, using a through-hole (bottomless) mold, unlike the above three methods.

[0003]

2. Description of the Related Art The prior art for directly and continuously casting thin slabs using a through mold is disclosed in U.S. Pat. No. 4,463,570.
No. 2 (conventional example I). The mold of the conventional example I is shown in FIG.
As shown in the figure, the space between the pair of long side walls (the dimension that becomes thicker in the cast piece) is widened only at the center of the upper end of the mold, and narrowed at both ends. Is a mold having an irregular cross-sectional shape that is smaller as approaching the lower end of the mold. The reason for widening the interval between the pair of long side walls only at the center of the upper end of the mold is that it is necessary to insert an immersion nozzle N for pouring into the upper end of the mold, and if the thickness is smaller than the nozzle diameter, the nozzle N Due to the inability to insert. However, in such a mold having a different cross-sectional shape at the upper end and the lower end of the mold, since the cross-sectional shape of the mold changes in the vertical direction, there is a mold oscillation that vibrates the mold up and down to facilitate drawing of the slab. There is a problem that is difficult. Therefore, as an improvement of the disadvantage of the conventional example I, as shown in FIG. 5, a bulging portion in which the interval between the long side walls of the pair of molds is widened not only at the upper end at the center but also at the lower end.
Japanese Patent Application Laid-Open No. Hei 2-500501 proposes a drum-shaped mold in which 52 is formed, that is, a large drum-shaped mold in which a central portion having a large space between long side walls continues from the upper end to the lower end of the mold. . In the above-mentioned conventional example II, the cast slab comes out of the mold in a shape in which the central portion is swollen, and the role of pushing the swollen portion is assigned to the guide roll below the mold. The shape of the guide roll becomes complicated to match the shape of the swelled slab,
Since the slab is pressed down to a rectangular cross section by the guide roll portion, it is necessary to open the guide roll when passing the guide roll at the tip end of the slab in the initial stage of casting, and there is a problem that the operation becomes complicated. Further, it is necessary to use a non-rectangular dummy bar corresponding to the cross-sectional shape of the mold, which makes the operation difficult.

[0004]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention has a simple structure of the guide roll below the mold, and does not require a complicated operation for opening the guide roll even when passing the tip of the slab. In addition, it is an object of the present invention to provide a mold for a continuous casting machine for thin slabs, which can use a dummy bar having an ordinary rectangular cross section and can directly cast a thin slab with good slab quality.

[0005]

A mold according to the present invention comprises a pair of long side mold walls and a pair of short side mold walls sandwiched between the pair of mold walls. The mold walls are substantially parallel to each other, and the pair of long side mold walls are provided with a taper that gradually reduces the distance between the mold walls from the upper end of the mold toward the lower end of the mold by at least the shrinkage amount of the solidified shell. It is characterized by having. In the present invention, the taper amount of the long side mold wall is preferably according to the following equation. {(B1 + T1)-(B2 + T2)} (B1 + T1)
× 100 = C where B1: distance between short sides at the top of the mold (near the meniscus) T1: distance between the long sides at the top of the mold (near the meniscus) B2: distance between the short sides at the bottom of the mold T2: distance between the long sides at the bottom of the mold C : Shrinkage of solidified shell while moving from upper end of mold to lower end of mold or more

[0006]

In the mold of the present invention, since the upper end and the lower end of the mold are parallel rectangles and have no irregular cross section, the resistance when pulling the slab while vibrating the mold is small.
The slab can be easily pulled out. Therefore, harmful vertical cracks and other defects do not occur in the slab. In addition, since the upper end of the mold is tapered on the long side while maintaining the thickness at which the immersion nozzle can enter, the thickness of the lower end of the mold is reduced, and a thinner slab slab can be directly cast. As described above, since a thin slab with a rectangular cross section has been cast at the time of leaving the mold, a guide gap below the mold does not require a roll spacing adjustment device, so the structure is simplified and the slab tip passes. Occasionally, a complicated operation such as adjusting (spreading) the interval between the guide rolls is not required, and the operation can be simplified since a conventional rectangular bar can be used.

[0007]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a mold M according to an embodiment of the present invention.
Is a pair of short side mold walls. The long side mold walls 1, 1 sandwich the short side mold walls 2, 2 to form a rectangular mold in plan view. The symbol me indicates the molten steel surface (meniscus) of the poured molten steel.

The short side mold walls 2 and 2 are substantially parallel to each other, and the distance B1 between short sides at the upper end of the mold (the vicinity of the meniscus, the same applies hereinafter) and the distance B2 between short sides at the lower end of the mold have the same dimensions. Long side mold wall 1,
Reference numeral 1 denotes a tapered wall in which the distance between the long sides decreases from the upper end of the mold toward the lower end of the mold, and the distance T2 between the long sides at the lower end of the mold is smaller than the distance T1 between the long sides at the upper end of the mold.

Here, assuming that the shrinkage amount of the solidified shell while moving from the upper end of the mold to the lower end of the mold is C or more, the taper amount of the long side mold walls 1 and 1 is preferably in accordance with the following equation. {(B1 + T1)-(B2 + T2)} (B1 + T1) .times.100 = C When the taper amount is larger than the contraction amount C of the solidified shell,
When an external force is applied to the solidified shell from the long side mold walls 1, 1, the short side shell is compressed. For this reason, the short side wall facing the short side shell is made concave so that the short side shell can easily inflate toward the short side wall. Conversely, if the taper amount is smaller than the shrinkage amount C of the solidified shell, the thickness of the slab slab on the mold exit side can be made thinner even though it can be made thinner, so that a thin slab slab can be cast directly. In addition, a reduction in the post-process is required, and a useless process is increased. When the amount of taper is in accordance with the above equation, none of the above problems occur, and the thin slab slab S can be directly cast.

FIG. 2 shows a slab S to be cast by the mold of FIG.
S1 indicates a solidified shell formed at the upper end of the mold, and S2 indicates a solidified shell formed at the lower end of the mold. As is clear from this figure, the solidified shell cooled while moving from the upper end of the mold to the lower end of the mold is crushed by the long-side mold wall by at least an amount corresponding to the contraction amount C, and the slab is cast. The thickness is thin. Moreover, in this case, since a large external force is not applied to the solidified shell, it is possible to directly cast the thin slab slab S without causing internal cracks in the slab and smoothly performing mold oscillation. It is.

FIG. 3 is a diagram for explaining the advantages of the present invention while comparing them, and shows solidified shells S1 and S2 during casting in a mold having a tapered short side. Normally, since the solidified shell has a large amount of shrinkage at the short distance B between the short sides, it is conceivable to first taper the short side to avoid internal stress and strain applied to the solidified shell. However, in this case, since the width dimension B of the slab S becomes small and the thickness dimension T remains large, the purpose of directly casting the thin slab slab S becomes difficult to achieve.

In the above-described embodiment, the short side mold wall 2 is formed in a flat plate shape which becomes narrower toward the lower side of the mold (forward in the slab drawing direction), and cooperates with the long side mold wall 1 to form a rectangular cross section. Although the example in which the slab S is cast is described above, the short side mold wall 2 is formed as a convex arc as shown in FIG. 4, or the end face of the slab S is formed as a chevron as shown in FIG. Inflated slabs S ', S "of substantially rectangular cross section
You may make it become.

According to the mold provided with the taper amount corresponding to the shrinkage amount of the solidified shell as in the relational expression in the present invention, even if the slab is crushed on the long side where the shrinkage amount is originally small,
It was confirmed that problems such as internal cracks did not occur. Therefore, according to the present embodiment, the following effects can be obtained. A thin slab slab can be cast at the lower end of the mold while having a width at which the immersion nozzle can enter at the upper end of the mold. Also,
The possibility of directly casting a thin slab slab without the need for rolling down in the subsequent process increases, so the roller apron guide roll does not require a roll spacing adjustment device to adjust the roll spacing, making the device simpler. Becomes Further, a complicated operation such as adjusting (spreading) the gap between the guide rolls when passing through the slab tip becomes unnecessary. Since the thickness can be reduced without applying a large external force to the solidified shell, internal cracks and the like which are quality defects for the cast piece are less likely to occur, and a high-quality slab cast piece can be cast. As a dummy bar for closing the bottom of the mold at the start of casting, an ordinary rectangular bar can be used, so that the operation is simplified.

[0014]

According to the present invention, the guide roll immediately below the mold may have a simple structure, and a complicated operation for adjusting the interval between the guide rolls even when passing through the tip of the slab is not required. It is also possible to provide a mold for a continuous casting machine for thin slabs that can use a normal rectangular one and that can directly cast a thin slab with good slab quality.

[Brief description of the drawings]

FIG. 1 is a perspective view of a mold according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing a shape of a solidified shell being cast by a mold according to the present invention.

FIG. 3 is an explanatory view showing the shape of a solidified shell during casting with a mold having a tapered short side.

FIG. 4 is a view showing a mold according to another embodiment of the present invention and its mold.
FIG. 4 is an explanatory view showing a shape of a solidified shell being cast in a mold.
You.

FIG. 5 shows a mold according to still another embodiment of the present invention;
Explanatory drawing showing the shape of the solidified shell during casting with the mold
It is.

FIG. 6 is a perspective view of a mold of Conventional Example I.

FIG. 7 is a perspective view of a mold of Conventional Example II.

[Explanation of symbols]

M mold 1 Long side mold wall 2 Short side mold wall B1
Distance between short sides B2 Distance between short sides T1
Distance between long sides T2 Distance between long sides

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Kanazawa 4-33, Kitahama, Chuo-ku, Osaka-shi, Osaka Sumitomo Metal Industries, Ltd. (72) Inventor Takashi Kawakami 5-2 Sokaicho, Niihama-shi, Ehime Sumitomo Heavy Industries Machinery Co., Ltd. Niihama Works (72) Inventor Taiji Araki 5-2 Sokai-cho, Niihama City, Ehime Prefecture Sumitomo Heavy Industries Machinery Co., Ltd. Niihama Works (72) Inventor Masahiro Ikeda 5th Sokai-cho, Niihama City, Ehime Prefecture No. 2 Sumitomo Heavy Industries Machinery Co., Ltd. Niihama Works (72) Inventor Kozaburo Tsujita 5-2 Sokaicho, Niihama-shi, Ehime Prefecture Sumitomo Heavy Industries Machinery Co., Ltd. Niihama Works (56) References JP-A-7-232241 (JP) JP-A-7-256399 (JP, A) JP-A-2-247059 (JP, A) JP-A-6-297101 (JP, A) 65451 (JP, U) WO 93/17817 (WO, A1) (58 ) investigated the field (Int.Cl. ^6, DB name) B22D 11/04 311 B22D 11/00 B22D 11/16 106

Claims (2)

(57) [Claims] 1. A pair of long side mold walls and a pair of short side mold walls sandwiched between the pair of long side mold walls, wherein the pair of short side mold walls are substantially parallel to each other. Wherein the pair of long side mold walls are provided with a taper that gradually reduces the distance between each other from the upper end of the mold toward the lower end of the mold by at least the shrinkage amount of the solidified shell. Mold for continuous casting machine for thin slabs. 2. The method according to claim 1, wherein {(B1 + T1)-(B2 + T2)}.
(B1 + T1) × 100 = C where B1: distance between short sides at the upper end of the mold (near the meniscus) T1: distance between the long sides at the upper end of the mold (near the meniscus) B2: distance between the short sides at the lower end of the mold T2: length at the lower end of the mold 2. The continuous slab for thin slabs according to claim 1, wherein the distance between sides C: the amount of shrinkage of the solidified shell while moving from the upper end of the mold to the lower end of the mold or more, and the amount of taper of the long side mold wall follows the above equation. Casting machine mold.