JPS60121048A - Heat insulation method of short side wall of continuous casting machine for thin billet - Google Patents

Abstract

PURPOSE:To retard surely the formation of solidified shells on short side walls by disposing heat insulatable holding plates adjacently to the inside of the short side wall, conducting electricity to the heaters embedded in the short side walls to heat the short side walls and removing the holding plates at the start of casting. CONSTITUTION:Heat insulatable holding plates 12 are installed along the front surfaces of refractory parts 6a, 7a of short side walls prior to the start of casting. Heat dissipation in the stage of heating the parts 6a, 7a by heaters 11 is prevented to improve the holding effect. A molten steel 1 is poured into the mold after the plates 12 are removed in the stage of starting casting. The efficient holding of the short side walls is accomplished without requiring large electric power and without generating dew condensation to a metallic belt.

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a short side wall heat retention method for a thin slab continuous casting machine.
Insulation of fixed short side walls prior to the start of casting of a thin slab continuous casting machine (hereinafter referred to as belt caster) that directly produces thin steel plates (sheet bars, etc.) with a thickness of 50 tnx or less from molten metal, especially m-steel. Regarding the heating method, in particular, it is necessary to ensure slow solidification of the short side of the slab in contact with the short side wall, to efficiently maintain heat so that the slab can be drawn out smoothly, and to prevent steam explosions. We propose a technology that is advantageous for performing safe thermal insulation heating.

(Prior art and its problems) There are various types of continuous casting machines, ie belt casters, that continuously manufacture steel plates such as sheet bars directly from molten steel. Figure 1 shows one of the typical ones.
Show one.

The synchronous belt caster shown in Fig. 1 is of the vine narrowing type, and the synchronous belt caster is of the vine narrowing type.
A plurality of guide rolls 8a, respectively, while maintaining a gap for holding the casting material such as.

8b, 80.8'a, all,, 8'Ot-Metal belts 4.5 supporting a pair of long side surfaces arranged opposite to each other, and a metal belt 4°5 near each side edge between the metal belts. The fixed short side walls 6 and 7 for the short side surfaces are in close contact with each other to form a casting space that is confined on four sides. In particular, the short side walls 6, 7 are designed so that the diameter of the injection nozzle 8 (approximately No. 0 fi
Considering W< ), it is necessary to have a structure having at least a lining layer of refractory material having a generally inverted triangular shape that gradually tapers toward the wide upper part and the lower part and has a constant width.

In such a conventional belt caster, the short side wall 6,
7, by heating at the time of @ production, especially at the start of casting,
The solidified shell 2 formed there must be formed later than the solidified shells on the other metal belts 4 and 5 (on the long side side), so that the growth rate of thickening must be slowed down. The reason for this is that, for example, in order to cast a thin steel plate of about 30 mm, a considerable amount of narrowing is required, and if a solidified shell forms on the short side walls 6 and 7 at the same rate or faster than on the long side, the casting This is because compression occurs in the lower part where the space is narrowed, resulting in wrinkles, and the resistance to pull-out increases, so that in extreme cases, pull-out may not be possible at all.

For this reason, as in Japanese Patent Application Laid-open No. 5B-082551, which the present inventors proposed prior to the present invention, the inner surface is made of refractory material and at the same time a heater is buried inside to heat the short side wall. Alternatively, prior to the start of casting, partition plates are erected at a distance on the short side and inside the wall, and the flame of a gas burner is radiated into the gap to heat it, thereby slow solidifying the 6°7 solidified shell on the short side wall. there was.

However, in the above-mentioned prior art, the D heat method uses a heater embedded in the short side wall, but since the outside of the short side wall is not cooled by the water-cooled back plate, it requires a large amount of electric power to achieve sufficient yx humidity temperature. There were problems in that the short side walls, especially the refractory parts 6a and 7a, had to be thickened, and furthermore, it was not possible to sufficiently heat up to the narrowing end (the tip of the narrowing part). On the other hand, when a gas combustion flame is used, there is a risk that moisture contained in the gas may condense on the surface of the metal belt 4.5 and come into contact with the poured metal, causing an explosion.

(Objective and Summary Structure of the Invention) An object of the present invention is to overcome the drawbacks of the above-mentioned conventional heat retention method. For heat retention, ・(1) Place an insulating board adjacent to the inside of the short side wall, and turn the short side wall into B port by energizing the heater buried inside the short side wall. (2) A method for keeping a short side wall of a continuous thin slab casting machine heated, and removing the heat insulating plate at the start of casting; Place a heat insulating board,
Thereafter, the short side wall is heated by energizing the heater in the heat insulating plate and the heater buried in the short side wall at the same time, and the heat insulating plate is removed at the start of casting. By adopting the following short side wall heat retention method, the generation delay of the short side solidified shell was reliably and efficiently achieved, which in turn enabled smooth continuous casting of thin-walled slabs.

(Structure of the Invention) FIGS. 2 to 4 are views of fixed short side walls used for carrying out the method of the present invention, and the short side walls 6 and 7 have a refractory portion 6a on the inner surface facing the casting space, 7a, and a water-cooled back plate 10 is provided on the outer surface of the refractory.
, 7a, a heater 11 is embedded. In the case of the short side walls 6 and 7 used in the present invention, this heater 11 includes a refractory part 6a,
The purpose is to heat the lower part of the refractory part 7a, and since the temperature of the refractory part 6a, 7a itself increases during casting in the longitudinal direction of the central part, the temperature of the refractory part 6a, 7a itself rises as it comes into contact with the molten steel, so a carbon shell 11' having excellent heat resistance is used.

In the method of the present invention, prior to the start of casting, an insulating heat insulating plate 12 is installed along the front surface (inside) of the short side wall large-sized parts 6a and 7a, and when the heater 11 is heated with electricity, The purpose is to strengthen heat retention.

As a first method, as shown in FIG. 8, a heat-insulating heat-insulating board 12 of approximately 80 recesses, such as Karaor, is set, and the refractory portion 6a is heated by the heater 11.

7a prevents heat dissipation during heating and increases the heat retention effect,
When starting casting, the heat insulating plate 12 is removed and then the molten steel 1 is injected.

As a second method of the present invention, as shown in FIG.
．． , 13 to heat and keep warm both the refractory parts 6a, 7a and the heat insulating plate 12, and the heat insulating plate 12 is pulled up at the start of casting. A more preferable embodiment of this method is that the heat insulating plate 12
In order to prevent heat dissipation on the inner surface of the casting space side, a heat shield plate 1.4 such as Kao wool or ceramic fiber is further added.
It is preferable to bond and combine 1. If the short side walls 6 and 7 are heated by energizing the heaters 11 and 18 through the attachment and detachment of the heat insulating plate 12 as described above at the start of casting, large electric power is not required. In addition, heat can be efficiently maintained on the short side walls without causing dew condensation on the metal belts 4 and 5.

(Example) According to the inventors' calculations, (a) In the conventional heat insulation method, molten cyanide is used as the material of the short side wall.
al Using fused silica (thermal conductivity 2/m-h-'), 100
When heating up to 0'C, heat radiation Q to the back plate: 1460 Kca
Heat radiation to the l/h side Q m ' 1200 Kcal
,/h Heat radiation to the inner surface Q a: 9650Kcal/
/11, the total heat dissipation Q is 12310 KOal/h
Teal.

If this was attempted to be ensured only by a heater buried in the short side wall, approximately 20 KW/H of power would be required.

On the other hand, according to the method of the present invention, the heat radiation Q to the inner surface is
8' is only 0a1/h at 840, and the total heat radiation Q is only 0a1/h at 8000, so the power required for this is only about 5.0Kw/h, making efficient heat retention possible. I understand.

In addition, in an example of the method of the present invention in which a heater is also embedded in the heat insulation board, the above power is 1.5Kw/H1 for the heater on the short side wall.
If the heater on the insulation plate side is supplied with 8.5Kw/H, it will be about 40
The lowest surface temperature of the short side wall becomes 910°C in minutes, making it possible to average 960°C as a whole, and even when the heat insulation plate is removed, there is little humidity drop, so a solidified shell on the short side is formed. This allowed for a smooth casting process.

(Effects of the Invention) As explained above, according to the present invention, the short side wall can be effectively heated and kept warm, which is advantageous in terms of thermoeconomics, and the drawing process is performed to directly cast a thin plate from molten metal. In addition to being able to operate smoothly without any casting load, it is also effective for safe casting work.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a continuous thin slab casting machine, Fig. 2 is an exploded perspective view showing an example of the short side wall used in the method of the present invention, and Fig. 8 is a perspective view of a continuous thin slab casting machine. FIG. 4 is a sectional view showing a state of an embodiment to be described. FIG. 4 is a sectional view showing a state of an embodiment to explain another method of the present invention. ■... Molten steel, 2... Solidified shell, 8a~sla・
... Guide roll, 4.5 ... Metal bell), 6.7 ... Short side wall, 8.
... Injection nozzle, 9... Slab, 10... Back plate, 11.13... Heater, 12... Heat insulation plate, ■4... Heat shield plate. Patent applicant: Kawasaki Steel Corporation

Claims (1)

[Claims] L) A pair of metal belts for the long sides that move around an axis, and a tapered fixed short side wall for the short sides that is in close contact between the metal belts. For the thin slab continuous casting machine that is combined with 1. A short side wall heat retention method for a continuous thin slab casting machine, characterized in that the short side wall is heated by energizing a heater buried in the side wall, and the heat insulation plate is removed at the start of casting. λ Thin casting that involves a combination of a pair of metal belts for the long sides that are arranged facing each other and that rotate, and a tapered fixed short side wall for the short sides that is in close contact between the metal belts. For single continuous casting machines, in order to keep the short side walls warm at the start of casting, an insulating heat insulating plate with a heater embedded adjacent to the inside of the short side walls is installed. Heat retention of the short side wall of a continuous thin slab casting machine, characterized in that the short side wall is heated by energizing the heater and the heater buried in the short side wall at the same time, and the heat insulation plate is removed at the start of casting. Method.