JP2820365B2 - Dummy sheet for twin-drum continuous casting machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dummy sheet for smooth casting in a continuous casting of a thin metal ribbon using a twin-drum continuous casting machine.

[0002]

2. Description of the Related Art FIG. 1 shows an outline of a twin-drum continuous casting machine. This casting machine comprises a pair of cooling drums 1, 1 rotating in parallel and in opposite directions,
A pool 3 is formed by a pair of side weirs 2 and 2 pressed against both end surfaces of 1. At the start of casting, after inserting the dummy sheet 4 into the gap between the pair of cooling drums 1, 1, the molten metal M such as molten steel is supplied to the pool 3. The molten metal M solidifies and adheres to the dummy sheet 4, and cools and solidifies on the peripheral surfaces of the cooling drums 1, 1 to solidify shells G,
Generate G. When the solidified shells G have a predetermined thickness, the cooling drums 1, 1 are rotated at a low speed. The solidified shells G, G move in synchronization with the cooling drums 1, 1 and are integrated at the closest point of the cooling drums 1, 1 to form a metal strip having a plate thickness of about several mm. The metal ribbon is wound together with a dummy sheet on a winder (not shown). During this time, the level of the molten metal in the pool 3 gradually rises, and when it reaches a predetermined level, the cooling drums 1 and 1 are rotated while maintaining the level of the molten metal.

[0003] In the metal ribbon manufactured in this manner, the sheet thickness is close to the product sheet thickness, so that the conventional hot rolling process can be omitted, and the cold rolling process can be performed only slightly.
The process and equipment can be simplified.

[0004]

However, when a relatively high melting point steel such as SUS430, electromagnetic steel, or carbon steel is cast using this casting machine, a slab immediately after leaving the cooling drum 1, 1 is obtained. In some cases, the surface of the steel sheet was torn and molten steel flowed out, or the joint of the dummy sheets was broken, so that casting had to be interrupted. The present inventors considered the cause as follows. That is, in the early stage of casting, since the level of the molten metal in the pool 3 is low, the pouring nozzle (immersion nozzle) is in a non-immersed state (open casting), and since the casting speed is low, the liquid is discharged from the pouring nozzle. It is considered that a phenomenon (hereinafter, referred to as shell washing) in which the solidified shell is melted by the molten steel flow occurs. Therefore, this phenomenon is likely to occur in relatively high melting point steels such as SUS430, electromagnetic steel, and carbon steel having a high molten steel temperature.

[0005] Further, if the shell washing occurs and solidification becomes insufficient, solidification and fixation of molten steel to the dummy sheet also becomes insufficient. A portion having insufficient solidification and fixation has a high risk of breaking during transportation due to low strength.

As a method for solving such a problem, a method of supplying a molten metal to a pool in a state in which a heat insulating material is adhered to a peripheral surface of a cooling drum (Japanese Patent Laid-Open No. 64-66048).
Japanese Patent Application Laid-Open No. 1-228650) and a dummy sheet provided with an easily meltable metal foil along the peripheral surface of a cooling drum at the leading end of a dummy sheet. However, when SUS430, electromagnetic steel, carbon steel, etc. are cast by such a method, the slab surface is broken and the molten metal flows out,
Also, the dummy sheet joint was broken.

Accordingly, the present invention provides a method for continuously casting relatively high melting point steel such as SUS430, electromagnetic steel, and carbon steel using a twin-drum type continuous casting machine. It is an object of the present invention to prevent the outflow of steel sheets and breakage of a dummy sheet joint portion, and to smoothly cast.

[0008]

According to the present invention, there is provided a dummy sheet for a twin-drum continuous casting machine according to the present invention, comprising a pair of cooling drums rotating in parallel and in opposite directions to each other, and having both end faces of the cooling drum. In a continuous casting machine for supplying molten steel from a discharge hole of a pouring nozzle to a peripheral surface of the pair of cooling drums to cast a metal ribbon into a pool of water formed by a pair of pressed side weirs. A dummy sheet inserted into the gap between the pair of cooling drums at the start of casting ,

[0009] The dummy sheet, wherein the distal end portion of the dummy sheet and a metal plate substantially along the entire width region of the circumferential surface is attached to the pair of cooling drums, the thickness of the metal plate ejection of the pouring nozzle The part facing the hole is thicker than the other parts.

[0010]

[Action]

When such a dummy sheet is inserted into the gap between the pair of cooling drums, the portion of the peripheral surface of the cooling drum facing the discharge hole of the pouring nozzle is covered by a thick metal plate. When molten steel is supplied to the pool in such a state, the molten steel discharged from the discharge hole of the pouring nozzle becomes a metal plate.
After colliding with the thick part of the metal plate , it flows along the thin part of the metal plate and accumulates in the V-shaped part formed by the metal plate, and the molten steel passes through the gap between the metal plate and the cooling drum, and It is supplied to the peripheral surface. The molten steel supplied to the peripheral surface of the cooling drum is cooled by the metal plate and the cooling drum to generate a solidified shell. At this time, the pouring nozzle discharges
Since the solidified shell in the portion facing the hole is covered by the thick portion of the metal plate , melting (shell washing) by molten steel discharged from the discharge hole of the pouring nozzle is suppressed . Te was therefore <br/>, the thickness of the solidified shell that is uniform across the slab width direction, thereby preventing the outflow of the molten steel due to breakage of the solidified shell.

Further, as the thickness of the solidified shell becomes uniform in the width direction of the slab, solidification and fixation of the molten steel to the dummy sheet is promoted, and the strength of the connection portion of the dummy sheet is increased. By rotating the cooling drum in such a state,
When the dummy sheet connection portion is pulled out, breakage of the dummy sheet joint portion can be prevented.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. Figure 2 shows a state actual施例shows a, the twin drum type continuous casting machine described in FIG. 1, fitted with a dummy sheet 5 of this embodiment of the present invention. The dummy sheet 5 is inserted between the pair of cooling drums 1 and 1 and has a thickness in the range of 0.2 to 1.0 mm and a width substantially equal to the width of the slab to be cast. The material of the dummy sheet 5 is a general mild steel .

[0014] The distal end portion of the dust Mishito 5, and substantially a metal plate 6 along the entire width is attached on the circumferential surface of the pair of cooling drums 1, 1, in the metal plate 6, the discharge hole of the teeming nozzle 7 8
The thickness of the metal plate 6A in the portion facing the metal plate 6A is thicker than the metal plate 6B in the other portion. The thickness of the metal plates 6A and 6B is, for example, such that the steel type to be cast is carbon steel and the molten steel temperature is 15
In the case of 60 ° C., the thickness of the metal plate 6A is 0.5 mm,
The thickness of the metal plate 6B is 0.2 mm. The metal plate 6A
Is a width for receiving the flow of molten steel discharged from the discharge hole 8 of the pouring nozzle 7.

As shown in FIG. 2 , when the dummy sheet 5 is inserted into the gap between the pair of cooling drums 1, 1, the peripheral surface of the cooling drum 1, 1 is covered with the metal plate 6. The metal plate 6 A and 6A are opposed to the discharge hole 8 and 8 pouring nozzle 7. When molten steel is supplied to the pool 3 in such a state, the discharge holes 8, 8 of the pouring nozzle 7, as shown in FIG.
After flowing toward the metal plates 6 and 6, the molten steel M flows along the metal plates 6 and 6 and accumulates in a V-shaped portion formed by the metal plates 6 and 6. Through the gap D between the metal plate 6 and the cooling drum 1, the cooling drum 1,
1 is supplied to the peripheral surface. The molten steel M supplied to the peripheral surfaces of the cooling drums 1, 1
It is cooled by the cooling action of the solidification shell in the gap D
Is generated. Opposite the discharge holes 8, 8 of the pouring nozzle 7.
Portion of the solidified shell is because they are covered by the metal plate 6 A, 6 A (FIG. 2), dissolved by the molten steel M to be discharged from the discharge holes 8, 8 of the pouring nozzle 7 (Shell washing) is suppressed . Accordingly, the solidification shell is uniform across the slab width direction,
By increasing the thickness, the outflow of molten steel due to the breakage of the solidified shell can be prevented .

Further, as the thickness of the solidified shell uniformly increases in the slab width direction, solidification and fixation of the molten steel to the dummy sheet 5 is promoted, and the strength of the connection portion of the dummy sheet is increased. By rotating the cooling drums 1 and 1 in this state and pulling out the dummy sheet connection portion, breakage of the dummy sheet connection portion can be prevented. The cross section of the pouring nozzle may be an ellipse or a rectangle other than a perfect circle, and in this case, the discharge holes may be expanded horizontally. Further, the metal plate may be formed by a wire mesh.

[0017]

According to the dummy sheet of the present invention, a metal plate is attached to the distal end of the dummy sheet inserted into the gap between the pair of cooling drums along the peripheral surface of the cooling drum .
This metal plate has a portion facing the discharge hole of the pouring nozzle .
The plate thickness is thicker than other parts. When the molten steel is supplied to the pool using the dummy sheet, the molten steel discharged from the discharge hole of the pouring nozzle flows toward the thick portion of the metal plate, and then flows along the entire metal plate, It accumulates in the V-shaped portion formed by the metal plate and solidifies.
Also, molten steel passes through the gap between the metal plate and the cooling drum,
It is supplied to the peripheral surface of the cooling drum. Cooling of the molten steel supplied to the peripheral surface of the cooling drum is promoted by the metal plate and the cooling drum, and the formation of a solidified shell is promoted. At this time
Since the solidified shell in the portion facing the discharge hole of the pouring nozzle is covered by the thick portion of the metal plate , melting by molten steel discharged from the discharge hole of the pouring nozzle is suppressed. Therefore, since the thickness of the solidified shell uniformly increases in the slab width direction, the solidified shell can be prevented from being broken. For this reason, a cast piece with excellent surface properties can be manufactured.

In addition, as the thickness of the solidified shell uniformly increases in the slab width direction, the dummy sheet 5
Solidification of the molten steel is promoted, and the strength of the dummy sheet connection part is increased. When the cooling drums 1 and 1 are rotated in this state to pull out the dummy sheet connection part, the breakage of the dummy sheet connection part is caused. Can be prevented. Therefore, casting can be performed smoothly without interrupting casting.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a twin-drum continuous casting machine.

2 is a perspective view showing a casting state before the start of using da Mishito of the present invention.

FIG. 3 is a cross-sectional view showing an initial casting state using the dummy sheet of the present invention.

[Explanation of symbols]

1 ... cooling drum 2 ... side weirs 3 ... basin portion 4 ... conventional dummy sheet 5 ... thick portions min 6B ... metal plate of the dummy sheet 6 ... metal plate 6A ... metal plate of the present invention the thin section min 7 ... Note Hot water nozzle 8: Discharge hole of pouring nozzle D: Gap between cooling drum and metal plate M: Molten steel (molten metal)

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B22D 11/06 330 B22D 11/08

Claims (1)

(57) [Claims] A discharge hole of a pouring nozzle is formed in a pool formed by a pair of cooling drums rotating in parallel and in opposite directions to each other and a pair of side dams pressed against both end surfaces of the cooling drum. A continuous sheet casting machine that supplies molten steel toward the peripheral surfaces of the pair of cooling drums to cast a metal ribbon, wherein the dummy sheet is inserted into a gap between the pair of cooling drums at the start of casting. At the leading end of the sheet, a metal plate is attached along substantially the entire width of the peripheral surfaces of the pair of cooling drums, and the thickness of the metal plate is such that a portion facing the discharge hole of the pouring nozzle is different from other portions. A dummy sheet for a twin-drum continuous casting machine, characterized in that it is thicker than that.