JPH05111740A - Continuous casting method - Google Patents

Abstract

PURPOSE:To prevent the flow-out of slag in a tundish caused by whirlpool by fitting a stopper ring having cylindrical ring structure to a stopper and mixing molten steel of the preceding heat and molten steel of the following heat in the tundish. CONSTITUTION:The stopper ring 5 is limited to float up with a stopper ring fitter 13 during casting and dipped into the molten steel, but when the molten steel surface level becomes below the stopper ring fitter 13, this ring is floated up on the molten steel surface and prevents the whirlpool. By this method, the casting speed is high by fitting the stopper ring 5 and even in the case the molten steel surface level is low, the whirlpool is not developed, and the flow-out of the slag is prevented and the steel quality is improved and further, the yield is improved because of the decrease of the remained molten steel quantity in the tundish at the end stage of casting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous casting method, and particularly to prevent the outflow of tundish slag due to vortices.

[0002]

2. Description of the Related Art In the conventional state without a stopper ring, a stopper prevents vortex formation when the casting speed of molten steel injected into the mold through the upper nozzle is low and when the water level on the molten steel surface is high. Although it was possible, vortices are generated when the water level on the molten steel surface is low and the casting speed is high, and the slag floating near the molten steel surface in the tundish is entrained and injected into the mold.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to prevent the outflow of tundish slag due to vortices.

[0004]

DISCLOSURE OF THE INVENTION The present invention advantageously solves the problems of the prior art, in which a pre-charged molten steel is placed in the tundish before completion of casting through a tundish. In a continuous casting method in which molten steel is left slightly and a post-charged molten steel having a different component system from that of the pre-charge is poured into the tundish to continuously cast different steel types, a stopper is used as a guide to raise or lower the molten steel surface in the tundish. The continuous casting method is characterized in that the stopper ring is fitted on the stopper and the molten steel of the pre-charge and the molten steel of the post-charge are mixed in the tundish.

The present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention.

In the ladle 1, molten steel flows to the tundish 4 through the long nozzle 2. The molten steel in the tundish 4 is poured into the mold 7 via the immersion nozzle 6.

Reference numeral 3 is a tundish stopper, and 5 is a stopper ring of the present invention, which is a ring body which moves up and down with the stopper as a guide as the molten steel surface in the tundish rises and lowers. It floats on the molten steel surface at the end of casting, prevents vortex generation at the end of casting, and prevents slag outflow in the tundish.

FIG. 2 is a stopper 3 showing the feature of the present invention.
3 is a detailed view showing the periphery of the upper nozzle 12 and the upper nozzle 12; FIG.

In the state without the conventional stopper ring 5 (FIG. 2 (b)), when the casting speed of the molten steel injected into the mold through the upper nozzle 12 is low and the water level on the molten steel surface 8 is When it was high, it was possible to prevent the generation of vortices such as 10 by the stopper of 3, but when the water level of the molten steel surface 8 is low and the casting speed is high, vortices such as 10 are generated. The slag 9 floating near the molten steel surface 8 in the tundish is entrained and injected into the mold through the upper nozzle 12.

In the present invention (FIG. 2 (a)), a stopper ring 5 is attached for the purpose of preventing the generation of this vortex.
As a result, surface tension is exerted between the molten steel and the stopper ring 5 to prevent contraction when vortices are generated.

By installing the stopper ring of 5, even when the casting speed is high and the water level on the molten steel surface is low, no vortex is generated, slag outflow is prevented and quality is improved.
The yield is improved by reducing the amount of remaining tundish in the final stage of casting, and the mixing area with the next charge is also reduced.

During casting, the stopper ring of No. 5 is immersed in the molten steel because its floating is restricted by the stopper ring stopper of No. 13, but when the molten steel water level is below the stopper ring stopper, the molten steel surface appears as shown in FIG. 2 (a). Prevents eddies from floating on the surface.

[0014]

While the conventional method (FIG. 2 (b)) could not prevent the outflow of tundish slag due to the generation of vortices at the low molten steel level and high speed casting, the method of the present invention (FIG. 2 (a)).
Therefore, even if high-speed casting is performed at a low molten steel level, no vortex is generated, and the outflow of tundish slag can be prevented.

Specifically, FIG. 3 shows the minimum value of the amount of residual hot water in the tundish showing a comparison between the conventional method and the present invention. In the prior art, the minimum value of the amount of residual hot water in the tundish is 3.6 tons for a tundish having a capacity of 50 tons. Since this can be prevented, it has become possible to reduce the minimum amount of the remaining tundish hot water to 1.2 tons.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

FIG. 2 is a detailed view showing the vicinity of a stopper and an upper nozzle, which is a feature of the present invention. (A) is equipped with a stopper ring. (B) is a state without a stopper ring.

FIG. 3 is a diagram showing the minimum amount of residual hot water in the tundish of the conventional method and the method of the present invention.

[Explanation of symbols]

 1 Ladle 2 Long Nozzle 3 Tundish Stopper 4 Tundish 5 Stopper Ring 6 Immersion Nozzle 7 Mold 8 Molten Steel Surface 9 Slag 10 Vortex 12 Upper Nozzle 13 Stopper Ring Stopper

Claims (1)

[Claims] 1. A pre-charged molten steel is left in the tundish before completion of casting through a tundish, and a small amount of the pre-charged molten steel is left, and a post-charged molten steel having a different composition system from the pre-charge is injected into the tundish. In the continuous casting method of successively casting different steel types, the stopper is used as a guide to move up and down according to the rise and fall of the molten steel surface in the tundish. A continuous casting method, characterized in that the two are mixed in a tundish.