KR20040057744A - Mold mounted tundish to float inclusion in the continuation cast machine - Google Patents

Abstract

PURPOSE: A mold is provided which is fabricated in such a manner that upper part, lower part and central part of the mold have different thickness to easily move nonmetallic inclusions into the center of the mold and secure flotation time of residual refractories in tundish and inclusions in molten steel by maximizing initial rotary power. CONSTITUTION: In a mold installed at an inner part of tundish corresponding to an exit position of the ladle in a continuous casting machine comprising ladle, tundish and molten steel transferring and controlling unit, the mold is characterized in that the mold is constructed in a rectangular pipe form four sides of which are closed, and upper and lower sides are opened, metal case having a proper thickness is formed on a certain part of the lower and upper parts of the rectangular pipe, metal case having thinner thickness is formed on an intermediate part of the rectangular pipe compared with the upper and lower parts of the rectangular pipe, wherein metal case having different thickness per rotational direction of an entrance is formed on the intermediate part of the rectangular pipe in such a way that molten steel is flown in that direction as metal case of the thinnest one side of the intermediate part is melted down, and molten steel is flown in as metal cases of adjacent two sides of the intermediate part of the rectangular pipe are sequentially melted down in a certain direction at certain time intervals so that swirl is generated.

Description

Mold mounted tundish to float inclusion in the continuation cast machine}

The present invention relates to a mold installed in the tundish of the lower ladle for inclusion inclusions in a continuous casting machine, and more specifically, to manufacture the mold so that the thickness of the lower, upper and center respectively different, the mold inside the tundish The present invention relates to a mold capable of maximizing the initial rotational force to facilitate movement to the center of the non-metallic inclusions and to secure the floating time of the residual refractory in the initial tundish and the inclusions in the initial molten steel.

Upper nozzle, slide gate and submerged nozzle (SEN) to prevent oxidation caused by the molten steel flowing from the tundish to the mold during contact in the continuous casting operation. Seal intermediate media such as entry nozzles. At this time, the non-metallic inclusions having a low specific gravity contained in the molten steel are pushed by the molten steel and moved to the nozzle wall having no velocity energy, thereby causing nozzle clogging to proceed. If the nozzle is clogged, it is difficult to obtain the flow rate required for normal casting speed, which causes punking, and this action causes the inclusions to enter the mold all at once, causing deterioration of the cast.

1 is a view showing a typical continuous casting machine, continuous casting machine ladle (10), tundish (20), tundish 20 and the mold delivery and control device between the mold (Delivery System) , 30), and a mold (Mold, 40).

In addition, the molten steel transfer and adjustment device 30 between the tundish and the mold of the casting machine, as shown in Figure 2, from the tundish bottom 1 to the upper nozzle 2, the upper plate (Upper Plate, 4), a lower plate 5, a lower nozzle 6, and an immersion nozzle 7, and the upper plate 4 and the lower plate 5 constitute a slide gate 3. On the other hand, the above-described molten steel transfer and adjustment device is a two-plate method consisting of the upper plate 4 and the lower plate 5, the three-plate method consisting of the upper plate, the middle plate (middle plate), the lower plate is There may be.

When non-metallic inclusions present in molten steel are moved from the tundish 20 to the mold 40, as shown in FIG. 2, the non-metallic inner wall of the refractory between the upper nozzle 2 and the immersion nozzle 7 is shown. Inclusions are attached, causing nozzle clogging, blocking the passage of molten steel to prevent casting, and attaching to the slide gate 3 to increase the opening rate, thereby reducing the flow rate and the position of the immersion nozzle. The center of gravity shifts to hinder flow in the mold.

In order to prevent such non-metallic inclusions from adhering to the nozzles and the upper / lower plates 4 and 5, there is a method using an eccentric slot nozzle as shown in FIG. The eccentric slot nozzle is a device added above the upper nozzle, and the inlet is inclined at an angle of θ as shown in Figs. 4A and 4B. Each corner portion is given R1, R2, R3, R4, R5, so that the reverse flow does not occur at the inlet and the flow path, and in particular, the inlet portion is induced to be curved inclination using the inclination angles θ, R2 and the like. In addition, when the vortex rotation flow occurs, a stagnant region is generated in the upper portion of the eccentric slot nozzle so that the upper portion is conical having a φ angle to prevent the nonmetallic inclusions from accumulating. The outer diameter of the eccentric slot nozzle seated on the upper immersion nozzle is enlarged by W so that it can be easily fixed by mortar or the like.

By applying rotational force to the molten steel using such an eccentric slot nozzle, the nonmetallic inclusion is moved to the center of the nozzle. However, since a small amount initially flows into the upper nozzle through the tundish by opening in the ladle, a small amount flows into the upper nozzle inlet without any rotational force, and the non-metallic inclusions contained in the molten steel are introduced into the upper nozzle inlet and upper portion. By being attached to the nozzle wall, the sliding gate, and the lower nozzle, clogging occurs from the beginning, making it difficult to secure the flow rate. In order to prevent the closed end, the delayed opening is performed. The delayed opening refers to a method of filling the molten steel in a tundish without opening the slide gate by a predetermined amount, and then opening the slide gate to start casting when a certain height is secured.

However, during the delayed opening, adhesion of non-metallic inclusions to the upper nozzle inlet, the upper nozzle wall and the slide gate other than the lower nozzle already occurs. As a conventionally known technique for preventing such adhesion, there is a method of opening a slide gate after securing a certain amount of molten steel while preventing the access of inclusions by injecting argon, which is an inert gas into the upper nozzle, to generate bubbles. As the argon bubble descends downward along the nozzle and flows into the mold, the argon bubbles are formed directly under the slab surface, thereby affecting the quality.

Therefore, the present invention is to solve the problems of the prior art as described above, the object of the present invention is to produce a mold so that the thickness of the lower, upper and center respectively different, by providing the mold inside the tundish, the initial rotational force It is to provide a mold that can be easily moved to the center of the non-metallic inclusions by maximizing, and to ensure the floating time of the residual refractory in the initial tundish and the inclusions in the initial molten steel.

1 is a schematic diagram of a typical continuous casting machine.

Figure 2 is a schematic diagram of the molten steel delivery and control device from the general tundish to immersion nozzle.

3 is a cross-sectional view of a general eccentric slot nozzle seated.

4A and 4B are plan and front views of a typical eccentric slot nozzle.

5 is a view for explaining a mold according to the present invention;

The present invention for achieving the above object, in the continuous casting machine including a ladle and a tundish and molten steel transmission and adjustment device, the mold is provided in the tundish corresponding to the outlet position of the ladle, A rectangular tube shape of which the slope is blocked and the upper and lower sides are opened, and a certain portion of the lower portion and the upper portion of the rectangular tube are made of steel shells of appropriate thickness so as to secure the overall strength and the required molten steel height, and the middle portion of the rectangular tube. It is composed of a thinner than the lower and upper thickness of the shell, the middle portion of the inlet by varying the thickness of the steel bar by the rotation direction of the inlet, the thinner one side of the thinner middle part to melt, the molten steel flows in the direction The steel bar of two neighboring sides of the middle part is in turn melted in a predetermined direction with a time difference to allow molten steel to flow therein. Characterized in that a current is generated.

The present invention is provided at the bottom of the tundish at a position corresponding to the ladle outlet to facilitate delay opening and maximization of initial rotational force without special manipulation. That is, a square mold having different thicknesses is installed at the bottom of the tundish at which the exit of the ladle is located, and the initial dissipation force in the direction is generated by varying the time to dissolve in the molten steel by position and direction. By securing the amount of molten steel by height, the rotational force generation and the amount of molten steel secured at the same time, and by securing different thicknesses, at the same time can be compensated for the disadvantage that the shell of the mold is torn down.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 5 and 6.

5 is a view showing a mold installed in the tundish according to the present invention, the mold according to the present invention is installed on the bottom of the tundish in which the outlet of the ladle in FIG.

The mold according to the present invention is a rectangular tube shape of which the slope is blocked and the upper and lower sides are open, and the lower and upper portions of the slope are formed of a steel shell of sufficient thickness to secure the overall strength and the required molten steel height. Thinner than the top, the middle molten steel in the tundish first flowed into the top nozzle inlet. Furthermore, in order to prevent the molten steel of the middle portion from simultaneously gathering in all directions of the upper nozzle inlet and losing the initial rotational force, the thickness of the bar is changed by the direction of rotation of the inlet, so that the inflow direction is constant in the counterclockwise direction. Do it. By doing so, the molten steel initially flowing from the ladle is accumulated in the tundish by the mold installed in the tundish, and if a certain height is secured, the nonmetallic inclusions in the molten steel are injured, and after a certain period of time, in the molten steel The molten steel on one side of the thinnest part of the mold melts, and molten steel flows in that direction, and the molten steel flows in a certain direction with a slight time difference, and molten steel inflows, thereby generating a rotational flow. At this time, the upper thick steel bar keeps the shape, it is impossible to enter the upper molten steel containing the non-metal inclusions to ensure the separation injury time of the non-metal inclusions. In addition, the upper part of the mold is open for preheating the upper nozzle, and the lower part is located outside the upper nozzle. The rib generated inside is to prevent the molten steel from being pushed by the specific gravity when flowing into the center of the tundish flow in the direction of the upper nozzle.

Although the present invention has been described above based on the preferred embodiments, these examples are intended to illustrate rather than limit the invention. It will be apparent to those skilled in the art that various changes, modifications, or adjustments to the above embodiments can be made without departing from the spirit of the invention. Therefore, the protection scope of the present invention will be limited only by the appended claims, and should be construed as including all such changes, modifications or adjustments.

In the present invention, by varying the thickness of the upper and lower parts of the mold and the thickness of the middle, it is easy to secure a sufficient amount of molten steel, the thickness of the middle portion is thinner than the upper and lower parts, so that the middle is first dissolved, the middle thickness By all the different by securing the difference of the melting time to ensure a constant inflow direction of the molten steel does not cause any problems due to the lack of initial molten steel and lowering the torque.

Claims (2)

In a continuous casting machine including a ladle and a tundish and molten steel transmission and adjustment device, a mold provided in the tundish corresponding to the exit position of the ladle, The mold, A rectangular tube shape of which the slope is blocked and the upper and lower sides are opened, and a certain portion of the lower part and the upper part of the rectangular tube is made of a steel shell of a suitable thickness so that the overall strength and the required molten steel height can be secured, and the middle portion of the rectangular tube is Consists of a thinner than the lower and upper thicknesses, The thickness of the steel bar is differently formed according to the rotational direction of the middle part, so that the thinner bar of the thinnest part of the middle part melts, so that molten steel flows in the direction, and the steel bar of two neighboring sides of the middle part has a time difference. A mold installed in the tundish of the continuous casting machine, characterized in that the molten steel is introduced into the molten steel in a predetermined direction in order to generate a flow of rotation. The method of claim 1, When the molten steel flows into the center of the tundish flow in the direction of the upper nozzle of the vortex rotation flow method, to prevent the square tube is pushed out by specific gravity, further comprising a rib provided inside the square tube Mold installed inside tundish of continuous casting machine.