JPS58224043A - Continuous casting method of thin metallic sheet - Google Patents

Abstract

PURPOSE:To produce stably a thin metallic plate having a good surface skin by oscillating the molten metal in a tundish and a casting mold, and maintaining the molten metal at a high temp. through slag by Joule heat thereby maintaining the uniformity of the molten metal and preventing the sticking of the ingot. CONSTITUTION:While a tundish 1 is moved back and forth in the longitudinal direction of a water cooled casting mold 4, molten metal 2 is charged continuously into the mold 4 under oscillation in the longitudinal direction thereof. Said mold 4 has an upper broad part 4c where a molten flux bath 10 is stagnated and a lower narrow part 4d which defines the sectional shape of a solidified ingot 5 on the inside surface. The molten metal 2 charged in the mold 4 solidifies in the form of embedding therein the dummy bar head charged in the part 4d. When the level of the metal 2 arrives at a prescribed position, the ingot 5 having a thin wall thickness and a broad width is drawn downward. Electricity is conducted in this stage between the non-consumable electrode 7 in a slag bath 10 and the ingot 5. The bath 10 is maintained at a high temp. by the Joule heat generated by the electric current and the molten metal in contact therewith is kept at a high temp.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for stably and continuously casting ferrous or non-ferrous metal thin plates, particularly thin plates with a wall thickness of 50 mm or less.

Figure 1 shows a conventional continuous casting method for thin metal sheets.

In FIG. 1, 01 is a tundish into which molten metal 02 is poured from a ladle (not shown) and is temporarily stored therein. A nozzle 05 is attached to the lower part of the tundish 01, and the molten metal 02 in the tundish 01 is injected into the mold 04 through the nozzle 05. The mold 04 forms the shape of the slab to be cast, and the molten metal 02' injected through the nozzle 05 is cooled and solidified in the mold 04 to form a solidified slab 05.

For this reason, the mold 04 has a structure in which cooling water circulates, and the inlet of the cooling water is 04a.

The exit is 04b. 06 is a secondary cooling water injection pipe surrounding the solidified slab 05, into which cooling water is introduced from the secondary cooling water inlet pipe 06a, and an injection port 06b bored in the inner surface of the secondary cooling water/injection pipe 06. The solidified slab 05 is injected from the solidified slab 05 to further lower its temperature.

The solidified slab 05 is pulled downward by pinch rolls (not shown) to become a continuously cast slab.

However, the above conventional method has the following drawbacks.

The molten metal 02 poured into the tundish 01 is poured into the mold 04 through the nozzle 05fjf, as described above.

The inner diameter of the nozzle 05 is determined by the volume of the solidified slab 05 and the drawing speed, and must be made small when the cross-sectional area of the solidified slab 05 is small or when the drawing speed is slow. However, the nozzle of the conventional continuous casting method
The inner diameter d of the nozzle 05 is 1 due to the fear that the inner hole of the nozzle 05 will be clogged.
The average number is 5 or more, and even in special cases, the minimum is about 10. Therefore, by conventional continuous casting method,
For example, when completely casting a thin plate with a wall thickness of 20 mm or less, the nozzle 0
2. So-called immersion nozzle 4 that immerses 5 into the molten metal 02' in the mold 04. □, 1□yo, □ya. 4°, Oh. , we have no choice but to adopt a method of pouring the metal by drilling. In such a pouring method, air and nonmetallic inclusions are drawn into the molten metal, and not only is it impossible to obtain a sound solidified slab 05'z, but also the molten metal 02' partially sticks to the wall of the mold 04, and then The molten metal poured into the mold 04 is not sufficiently supplied to the molten metal pool in the mold 04,
There is a drawback that the solidified slab 05 often breaks.

The present invention eliminates the drawbacks of the conventional continuous casting methods described above and provides a continuous casting method that can stably cast thin metal plates with a wall thickness of 50 mm or less.

That is, the present invention uses a water-cooled mold having on its inner surface an upper wide part for retaining molten slag, and a lower narrow part formed in contact with the lower part of the wide part and determining the cross-sectional shape of the solidified slab. The water-cooled mold is vibrated in the vertical direction, and molten slag is charged into the upper wide part of the water-cooled mold to completely form a slag bath, and 1. While reciprocating the tundish in the longitudinal direction of the cross section of the mold, molten metal is continuously poured and solidified between the non-consumable electrode placed in the slag bath and the lower narrow part of the water-cooled mold. Continuous casting of thin metal sheets, characterized in that thin and wide slabs are continuously cast while maintaining the entire slag bath at a high temperature by Joule heat generated in the slag bath by passing electricity between the solidified slabs. It is about the method.

The features of the method of the present invention can be summarized as follows: Q. A tundish equipped with a nozzle for pouring molten metal is reciprocated in the longitudinal direction (wide direction) of the cross section of the mold, so that the molten metal is poured as uniformly as possible. Casting, pouring into a mold.

■ Spread the upper part of the mold so that the nozzle can fit into it.
A structure in which the two wide parts and the lower narrow part that determines the wall thickness of the slab are fully connected is used.

(2) Vibrating the mold in the vertical direction to prevent the solidified slab from sticking to the mold.

■ To prevent the molten metal poured into the mold from solidifying in the wide part at the top of the mold, a molten slag bath is formed in the wide part.
The slag bath keeps the molten metal poured into the mold warm and cleans the molten metal.

■ In order to keep the molten slag at a high temperature as described above, a non-consumable electrode is held in the slag bath, and a current is passed between the electrode and the solidified slab, and the Joule heat generated in the slag bath raises the slag bath to a high temperature. to hold.

The method of the present invention can be suitably applied to ferrous and nonferrous thin-wall continuous casting methods, particularly thin-wall wide continuous casting methods with a wall thickness of 50 mm or less.

FIG. 2 shows an example of an embodiment of the method of the present invention.

In the figure, FIG. 5 is a view taken along the line Ill--Ill in FIG. 2.

1, 2, 5° 4.4a shown in Figures 2 and 5
, 4b, 5, 6y each of 6a and 6b is 1st
O4,02,05°04.04a,0 shown in the figure
4b, 05, 06, 06a, and 06b have the same functions and effects, so their explanation will be omitted here.

Reference numeral 40 denotes a wide part at the upper part of the mold 4, and its width is made wider than the mold narrow part 4d which determines the dimensions of the solidified slab 5 so that a normal nozzle 5 and a non-consumable electrode 7 can be accommodated therein. Therefore, the mold 4 used in the method of the present invention has a structure in which the upper wide part 4C and the lower mold narrow part 4d, which completely determine the solidified slab size, are connected in the longitudinal section. 7 is connected to the solidified slab 5 by a lead wire 9. A power source 8 is placed in the middle of the lead wire 9 so that a current flows between the non-consumable electrode 7 and the solidified slab 5.010 is a molten slag bath, usually At203-8i
02-CaO system is used. This slag bath 10 is heated and kept warm by Joule heat generated by the current flowing through the slag between the non-consumable electrode 7 and the solidified slab 5.

Reference numeral 11 denotes a tandish 1ff: a stand on which it is placed, and wheels 12 are connected to both ends thereof. Reference numeral 15 denotes a rail on which the four wheels 12 run when reciprocating in the A-A' force direction, and is fixed on a frame (not shown).

14 is a lever that vibrates the mold '4 in the vertical direction, and this lever 14 is driven by an eccentric cam 15 driven by a motor 16.
It moves up and down.

In FIGS. 2 and 5, Mn (051%)'ff: shown) is injected from a ladle (not shown) into the mold 4 through the entire nozzle 5 provided at the bottom of the tundish 1. At this time, the nozzle 5, which has an inner diameter of 15 mm, are installed in the width direction at intervals of 500 degrees.

The nozzles 5 are reciprocated in the longitudinal direction (A-A') of the cross section of the mold 4 by a drive device (not shown) on which the table 11 on which the tundish 1 in which they are installed is placed is reciprocated. Since the mold is reciprocated accordingly, the molten metal 2 discharged from the nozzle 5 is poured almost uniformly into the mold 4 in the longitudinal direction.

The molten metal 2 injected into the mold 4 solidifies in the form of a dummy bar head (not shown) inserted into the narrow part 4d of the mold.

When the position (level) of the molten metal 2 poured into the mold 4 rises at the upper part 1 of the mold narrow part 4d, when the dummy head is pulled out by a pulling device (not shown), the solidified slab is removed. 5 is pulled out downward from the lower part of the mold narrow part 4d.

At this time, the molten metal 2 poured into the mold 4 falls through the molten slag bath 10 charged in advance, so that it is refined and becomes clean and is kept warm by the slag bath 10.

Note that the molten slag bath 10 at the start of drawing is heated and heated separately.
It is formed by the powder flux that is melted and injected into the mold 4, but after that, the powder flux that is periodically charged is heated by the Joule heat generated by the electric current flowing between the non-consumable electrode 7 and the solidified slab 5. Furthermore, the mold 4 is vibrated in the vertical direction by a lever 14 driven by an eccentric cam 15 connected to a motor 16.The vibration conditions at this time are, for example, the above-mentioned molten carbon steel. When casting a thin slag with a wall thickness of 10 fi% and a width of 1000 cps, an amplitude of 10 cylinders and a frequency of 0.5 cpS were suitable.

Next, the solidified slab 5 pulled out from the mold 4 is further cooled by secondary cooling water injected from the injection port 6b on the inner surface of the secondary cooling water injection pipe 6, and the desired continuous casting is achieved. A thin plate is obtained.

According to the method of the present invention detailed above, the following effects can be achieved.

■ The tundish, which is equipped with a nozzle for pouring molten metal, is reciprocated in the longitudinal direction (wide direction) of the cross section of the mold, so the molten metal and the mold are uniformly poured, and the temperature distribution in the wide direction is relatively uniform. Therefore, surface defects can be prevented.

■ The upper part of the mold has a wide structure, so the wall thickness is 50 mm.
Even when casting thin slag with a thickness of less than 200 yen, a tundish equipped with a nozzle of a conventional diameter can be used as is.

(2) Since the mold is vibrated in the vertical direction, the solidified slab is prevented from sticking to the mold. Therefore, stable operation is possible without the solidified slab breaking during casting.

- The high-temperature molten slag bath formed in the wide part of the upper part of the mold prevents the poured molten metal from solidifying at the upper part of the mold, and also helps to clean the molten metal.

■ The molten slag bath is a VJ between the non-consumable electrode and the solidified slab.
Since the Joule heat generated by the flowing current keeps the molten metal at a high temperature, the molten metal poured into the mold is also kept at a high temperature, contributing to the formation of a beautiful casting surface.

(2) Due to the above effects, thin metal plates with a wall thickness of 50 mm or less can be stably obtained.

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining a conventional continuous casting method for thin metal sheets, Fig. 2 is a diagram for explaining an embodiment of the method of the present invention, and Fig. 5 is a diagram taken along the line ■-■ in Fig. 2. It is an arrow view. Sub-Agents 1) Meifuku Agent Ryo Hagiwara - Figure 1

Claims (1)

[Claims] A water-cooled mold is used, which has an upper wide part for retaining molten slag, and a lower narrow part that is formed in contact with the lower part of the wide part and determines the cross-sectional shape of the solidified slab. molten slag is charged into the upper wide part of the water-cooled mold to form a slag bath, and the molten metal is continuously poured while reciprocating the tundish in the longitudinal direction of the cross section of the mold. By applying electricity between a non-consumable electrode placed in the slag bath and a solidified slab solidified in the lower narrow part of the water-cooled mold, the slag is heated by the Joule heat generated in the slag bath. Continuous casting method for thin metal sheets characterized by continuously casting thin and wide slabs while maintaining a bath at a high temperature