JPS6117345A - Sealing and heat insulating method of tundish - Google Patents

Abstract

PURPOSE:To obtain economically and easily the billet of a clean steel contg. less inclusions by capping a tundish with a heat insulating material board, blowing an inert gas into the tundish in the initial period of pouring and dropping the heat insulating material board onto the molten metal so as to float thereon when the molten metal surface stabilizes. CONSTITUTION:The tundish 1 is sealed by the heat insulating material board 9 and gaseous Ar is supplied through burner holes 8 and the peripheral of a long nozzles 3 to purge the air in the tundish 1 prior to pouring of the molten steel. The molten steel is then poured from the nozzle 3 into the tundish 1 to prevent the oxidation of the molten steel in the tundish in the initial period for starting of casing. The supply of the gaseous Ar is stopped and the board 9 is broken and is dropped onto the molten steel in the tundish 1 when the molten flow and molten metal surface in the tundish 1 stabilize. The molten steel is thus insulated of heat and the oxidation thereof is prevented by shutting off the external air and the molten steel.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for sealing and keeping warm a tundish in continuous casting.

(Prior art) In continuous casting of molten steel, a lid is installed on the tundish.
It is widely practiced to prevent oxidation and maintain heat by supplying an inert gas such as Ar gas into the tundish (threaded tundish). (For example, JP-A-50-3
(Refer to No. 8630) However, in this shielded tundish injection method, the large and heavy lid is attached, resulting in poor workability for tundish maintenance. Furthermore, a large amount of inert gas (Ar gas) is supplied during the casting operation, which requires a large number of gas cylinders.

Furthermore, the above-mentioned conventional type was Tosu because the inside of the attached frame was lined with a refractory material.

(Points to be Solved by the Invention) This invention is intended to solve the above-mentioned conventional problems.It simplifies the workability of servicing the tandish and improves the sealing and heat retention of the tandish. The purpose is to provide a tundish (υ seal and heat insulation method) that can be used to completely clean steel.

According to the findings of the present inventors, in continuous casting of steel, it is especially necessary to improve the sealing performance of the tundish and to purge the air inside the tundish by supplying a large amount of inert gas such as Ar gas. It is a reed that stabilizes the molten metal level in the tundish at the beginning of casting, and after that, if the surface of the molten steel is sufficiently covered with heat insulating material to shut off the atmosphere and molten steel, and heat is maintained, it will extend over the entire length of the slab. It was found that clean steel slabs can be obtained using this method. This invention was made based on the above knowledge.

(Meaning point' + 1: Means for solving the problem) The present invention covers the tundish with a heat insulating board and blows an inert gas into the molten steel at the beginning of injection. ,
The method of sealing and keeping warm a tundish is characterized by lowering the above-mentioned heat insulating board, floating it above the molten steel, and additionally supplying a heat insulating material as necessary to keep the heat insulated.

The method of the invention will be explained below with reference to FIGS. 1, 2, and 3.

In the figure, 1 is a tundish, 2 is a ladle, and a long nozzle 3 is installed at the bottom of the tundish.
Molten steel is injected inside. Reference numeral 4 designates a submerged nozzle for pouring molten steel into a mold, which is closed by a stopper 5. Note that 6 in the figure indicates a slotted weir. 1i-j,i
This is a partial lid for a tundish with a f-installation, and a burner hole 8 for preheating the tundish is opened therein. 9 is a board made with the heat insulating material according to the present invention.For example, it is made by reinforcing fireproof paper with needles. ”, etc., but is not limited to this.

In the initial situation of this invention, as described above, the tundish was sealed with the heat insulating board 9. Prior to the injection of molten steel from the long nozzle 3, Ar was applied from around the burner hole 8 and the long nozzle 3v as shown in the Supply gas to purge the air in the tundish. Next, molten steel is injected from the long nozzle 3 to prevent oxidation of the molten steel in the tundish at the beginning of casting. Then, the amount of molten steel in the tandish increases (tandish volume if
・L) If the flow and level of the hot water are stable (approximately 50% or more), the supply of Ar gas is completely stopped and the insulation board 9 is destroyed by impact, etc., and the inside of the tundish is removed as shown in Figure 3. Drop it onto the molten steel. Thereafter, the heat insulating material 9a keeps the molten metal warm and blocks the atmosphere from the molten steel to prevent oxidation. In this case, if the necessary amount of heat insulating material 9a is insufficient due to the falling objects of heat insulating board 9, additional heat insulating material is separately supplied.

(Effect of the invention) The present invention, in which the heat insulating material is used both for sealing the Kuntish and for keeping the molten copper warm, makes it possible to easily attach clean copper slabs with few inclusions. It is something that can be done. When cleaning the tandish, it is extremely easy to maintain as it is similar to the regular open tandish, and the tandish can be rotated and used quickly.

GCC copper steel temperature j, poured at 1605℃, width 1.510
? When manufacturing 11 pieces of lI + lI x thickness 248 mm,
The present invention was put into practice in the following manner.

(1) 14M board material: Fireproof paper molding method: Reinforced with needle cap size: Vertical: 90 mm x Width: 60 mm x Thickness: 3
On15 non-sheet quantity...]0 wood weight...approximately 30R9 (2) Ar gas injection; 9-child...80Q, /:/
mj nol x yuo min (3) When the insulation board falls ・ ・
Falling after the amount of steel in the tundish reaches 9 tons or more (4J method of dropping the insulation board... Falling due to the weight of the additional insulation material (5) Amount of additional insulation material: 501 (as in 7 or more) Figure 4 shows the results obtained using Funatsune's method.

As is clear from FIG. 4), according to the example of the present invention, a clean cup was obtained over the entire length of the section, and this was comparable to that of the shield tongue.

[Brief explanation of the drawing]

Figures 1 to 3 are explanatory views of an example of the method of the present invention, with Figure 1 being a plan view, Figure 2 being a vertical sectional view, and Figure 3 being a longitudinal sectional view. Figure 24 is a graph showing the results of the example. Work...Tandish 2...Ladle 3...Long nozzle 4...Immersion nozzle 5...Stopper 9...Heat insulation Material board 9a...Heat insulation material

Claims (1)

[Claims] The tundish is covered with a heat-insulating board, and inert gas is blown in at the beginning of the molten steel injection. After the amount of molten steel increases and the molten metal level stabilizes, the above-mentioned heat-insulating board is dropped and floated above the molten steel. A method for sealing and keeping warm a tundish, characterized by additionally supplying a heat insulating material to keep warm.