JPS61186159A - Cooling method of continuous casting ingot - Google Patents

Abstract

PURPOSE:To improve yield and to extend the life of rolling rolls by sandwiching airtightly at least the tip and bottom surfaces of an ingot after continuous casting of a molten metal by endless belts up to the humidity at which quick atmospheric oxidation does no longer arise thereby cooling forcibly the top and bottom surfaces and preventing the surface oxidation of the ingot. CONSTITUTION:After the molten metal is cast to a solidified ingot 3 by continuous casting belts 11, 12, at least the top and bottom wide area surfaces thereof are airtightly sandwiched by the upper and lower endless conveying belts 1, 2 and press contact rollers and are forcibly cooled in this state by the cooling water of cooling boxes 4, 5. The surfaces are thereby cooled down to the temp. at which the quick atmospheric oxidation does not arise. Such ingot is sent to the succeeding stage. The yield of the ingot is improved and the life of the rolling rolls is improved by preventing the surface oxidation of the ingot.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method for cooling continuously cast slabs, which is heated to a predetermined temperature under atmospheric shielding using a cooling belt that is extremely effective in preventing oxidation of slabs. This paper proposes a technology that cools the materials while transporting them.

(Prior Art) A still hot slab G immediately after continuous casting of metal (hereinafter described as an example of "steel") is usually exposed to the atmosphere immediately after being extracted from the mold, so that the surface oxidation is significant. In particular, in the case of oxidized scales that are prone to form oxidized scale, those that are difficult to peel off, or those that undergo high-temperature grain boundary oxidation, if oxidation occurs, the cast slab There have been problems such as oxidized scale getting stuck on the inner surface, cracks on the surface of the slab, flaws on the surface of the slab, and shortening of the life of the rolling rolls.

In addition, the loss itself due to surface oxidation scale is 0.
．． Although it is not very large, about 1-1 m, the effect becomes so large that it cannot be ignored when the production volume is large or when casting slabs as thin as about 50 mm thick, and eventually the surface oxidation causes a huge amount of damage. This causes a decrease in yield.

Conventionally, as a method to solve the above-mentioned problems, the method disclosed in Japanese Patent Application Laid-Open No. 6-11900, which is characterized by coating (coating) a rust preventive agent on the surface of the slab, has been proposed.
No. 8-61955, the disclosed method and others have been proposed.

(Problems to be Solved by the Invention) The above-mentioned conventional technology requires the use of a D scale generation inhibitor (100 to 10009/Cm) and also requires a descaling process before rolling. There were problems with an increase in the production volume of slabs and a large surface area when casting thin slabs.

Therefore, the present invention aims to propose a method that can advantageously overcome the above-mentioned problems, and aims to establish a cooling method that can reliably prevent oxidation of hot slabs.

(Means for Solving the Problems) The present invention solves the above-mentioned problem and solves the problem of rapid atmospheric oxidation of the cast slab from the casting location when cooling the cast slab after continuous casting of molten metal. By airtightly sandwiching at least the two wide sides of the slab in a forced cooling loop provided in the slab drawing path until the slab is cooled to the lowest temperature at which The present invention proposes a cooling method for continuously cast slabs, which is characterized by conveying and cooling the continuously cast slabs.

(Function) The present invention utilizes a metal belt to transport slabs at the casting site, that is, at high temperatures when they exit the mold, and where the slabs are highly oxidized.
This is a method in which oxidation of the surface of the slab is prevented by carrying out the process using a metal transport belt and by keeping the ring belt in close contact with the surface of the slab, thereby shielding it from the atmosphere.

In order to shield the surface of the slab from the atmosphere through the above-mentioned circular belt, that is, the transfer metal belt, the belt and the surface of the slab must be airtightly sealed, and at the same time, the belt itself must be cooled while cooling the slab. must also be cooled. In order to meet these demands, in the present invention, as shown in FIGS. 1 and 2, a support guide for conveying the slab is provided on the opposite side of the transport belts 1 and 2 from the side facing the slab 8. Water film type cooling boxes 4..., 6... that also serve as water film cooling boxes are provided. A large number of nozzle holes 6 for water injection are opened in the water film type cooling boxes 4, 5 facing the belt 1.2.

The belts 1 and 2 are pressed against the surface of the slab 8 by the pressure of the flowing film of cooling water ejected from the nozzle hole 6, creating an airtight seal and cooling the slab at the same time, reducing the temperature of the slab surface. The temperature is brought to a point where rapid oxidation no longer occurs.

In the present invention, as a method for indirectly cooling the slab 3,
In addition to the method using the water film type cooling boxes 4 and 6, for example, a transportation belt l as shown in FIG. 8 may be used.

A large number of (EN rollers 7, 8, . (not shown) may be provided.

In short, the present invention constructs the cooling conveyance path of the slab with a belt, and uses this belt to at least cover two sides of the slab on the wide side.
This is a method of preventing oxidation of the slab surface by shielding the surfaces (four sides may be constructed with belts).

(Example) What is shown in FIG. 1 is an example in which the method of the present invention is applied to a horizontal belt caster, and the symbols 1 to 5 shown in the figure have the same configuration as described above. A pair of upper and lower metal casting belts 11.12, which substantially constitute a casting space, are arranged upstream and on the side of the transport belt 1.2 arranged after the secondary cooling zone of the slab 8. Further upstream thereof, a tandish 18 is provided. Melting inside Tanditshu 18! [
(For 3% grain-oriented silicon steel) Casting bell above) 11.1
2'' to form a cylindrical solidified shell, which is then sent to the transport belts 1 and 2.

The slab produced by the belt caster has a thickness of t) 80! It is a sheet bar with a width (W) aoosm and a drawing speed (V) of 3.9 m/Win, and is cast with a pull-out speed (V) of 3.9 m/Win, and a pair of upper and lower transport belts made of SUS 804 extending 18 m after the belt caster.゜2 is placed in close contact with the slab, and water film cooling boxes 4 and 5 are installed so that the sheet bar surface temperature becomes 400°C or less at the outlet.
The running water film was adjusted.

For comparison, a sheet bar was manufactured without using the transport belts 1 and 2 by cooling the sheet bar from the belt caster outlet on a roller table.

Table 1 shows the thickness and yield of oxide scale for each of the above sheet bars. As can be seen from this table, surface oxidation was drastically reduced to 1/30 by applying the method of the present invention, and the yield reduction rate was also better with the method of the present invention.

Table 1 (Effects of the Invention) As explained above, according to the present invention, surface oxidation of slabs can be prevented without using antioxidants. It is possible to prevent problems such as overloading, shortening the life of rolling rolls, or reducing product yield. In addition to the horizontal belt caster of the above embodiment, the present invention can also be applied to inclined belt casters, regular continuous casting machines, twin roll molds, block types, belt wheel types, etc., and can be applied to a wide range of applications. It has the effect of being able to do it0

[Brief explanation of drawings]

FIG. 1 is a schematic IIJ diagram of a slab cooling equipment illustrating the implementation state of the method of the present invention, and FIG. 2 and FIG. FIG.

Claims (1)

[Claims] 1. For cooling the cast slab after continuous casting of molten metal, a forced cooling system is installed in the slab drawing path from the casting point until the slab is cooled to the lower limit temperature at which rapid atmospheric oxidation occurs. A method for cooling continuously cast slabs, characterized in that the slabs are conveyed and cooled while being shielded from the atmosphere by airtightly sandwiching at least two wide surfaces of the slabs in a turning belt.