JPS59159250A - Continuous casting method and device for thin slabs - Google Patents

Abstract

PURPOSE:To control the thickness of a billet as desired by constituting a device of a horizontal endless belt rotating and moving in one direction under force cooling from the inside surface side, dam blocks on both side ends thereof, and a tundish provided with a horizontal spout disposed on the upper stream side of the endless belt in the moving direction thereof. CONSTITUTION:A casting mold is constituted of an endless belt 12 which is disposed horizontally and is forcibly cooled from the inside surface side and dam blocks 13 forming side walls on both side ends of said belt. A molten metal 1 is then supplied continuously from a horizontal spout 14 of a tundish 15 disposed on the upper stream side in the moving direction of the belt 12, and the levels of the molten metal surfaces respectively in the tundish 15, the spout 14 and the belt 12 are maintained roughly the same. The surface of the molten metal is covered with a heat insulating material 17 and while the molten metal is subjected to heat insulation and retaining of heat, the molten metal is forcibly cooled only from the inside surface side of the belt 12 by which the solidification of the molten metal 1 is progressed and the solidified metal is delivered onto a conveying table 7.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention allows the thickness of a slab to be freely controlled, allows for the easy production of ultra-thin cast bars with a thickness of 150 mm or more, and provides slabs without center segregation. The present invention relates to a continuous casting method capable of performing continuous casting, and a continuous casting apparatus for carrying out the method.

Technological innovations in various industrial fields in recent years have been remarkable, and the field of metal materials industry is no exception, with new technologies aimed at improving product quality, improving product manufacturing efficiency, and saving labor and energy. have been proposed one after another and put into practical use.

One of the representative methods is [Continuous casting method-1], which can produce sound slabs with good yield, little segregation, and almost no solidification shrinkage pores with high efficiency. It has become widely adopted as an alternative to the traditional ingot casting method.

FIG. 1 is a schematic diagram showing a typical example of this conventional continuous casting method. When molten metal 1 is injected into a mold 3 via a tundish 2, It is cooled to form a solidified shell 1, which is continued to solidify by repeating water cooling while holding its outer surface with a roller apron 5, and is drawn out as a slab by pinch rolls 6. Note that the reference numeral +37 is a transport table, which transports the iron 5 j'+' that is finally completely solidified.

It is true that this continuous casting method makes it possible to efficiently produce slabs with relatively little segregation, and that it has become possible to keep metal material manufacturing costs extremely low. However, since the obtained slab is cooled from its surroundings, especially from the upper and lower surfaces (wide side), the final solidification occurs near the center of the slab, and impurities are therefore concentrated in the center, resulting in center segregation. In today's world, where there is a demand for higher quality products, this has come to be recognized as a major problem1. In the continuous casting method, Q) The size of the mold is limited due to problems such as withdrawal of cast J4; ■ Since hot water is supplied by an immersion nozzle,
The mold size is limited;■ The slab is held by a mechanism called a roller apron;
The change in the spacing (which will be a big surprise in the evening) ■ The pulling out of υ1ji- is done by pinching it with pinch rolls, so the adjustment of the pulling force is delicate, and the spacing of the pinch rolls can also be changed. For reasons such as being troublesome, it is not possible to change the slab thickness simply and easily, and it is still considered impossible to reduce the thickness of the slab.3 Therefore, the conventional continuous casting method For example, when manufacturing steel slabs in one piece, the main target was slabs with a thickness of 200 mm or more, and the actual situation was that changes in slab thickness were to be kept to a minimum.

From the above-mentioned viewpoints, the present invention allows the thickness dimension to be freely controlled, and even ultra-thin slabs with a thickness of J-50 mm or less can be manufactured simply and easily. We conducted research through repeated trial and error in order to find a method to continuously and efficiently obtain slabs without internal defects due to center segregation, and to provide equipment that can reliably implement this method on an actual operational scale. /C result, (a,) An endless belt made of steel or the like that is wrapped around the left and right pulleys and rotates around the pulleys, and rotates around the pulleys as the endless belt moves. The endless belt moves in close contact with each other in straight lines to form side walls on both sides of the endless belt.A series of dam blocks constitutes a single-belt type continuous machine, that is, a twin Although it is known as a belt-type continuous casting machine, -
1- Belt removal (substantially the same as the device), this is installed horizontally, and while forcibly cooling the belt from the inner surface side, the belt is cooled from the top in the belt movement direction by melting the hot water gutter. Casting the molten metal into water is possible by continuously obtaining solidified slabs from the bank in the +-5 movement direction, and by appropriately controlling the amount of supplied metal and the casting speed. It is possible to freely change the thickness of the slab, and therefore the thickness of the slab can be freely changed. and eliminating hot water leakage from the gap between the endless belt and the dam block and the gutter,
Keep the molten metal surface on the endless belt at the same level as the molten metal surface on the tundish and the planting soil.
It is possible to solidify molten metal into a slab of constant thickness without causing ζ disturbance 1t, and therefore continuous casting of extremely thin steel slabs of 150+mn or less is possible. So, if you use the horizontally planted tongue caster as described above, you can easily adjust the thickness of the slab by adjusting the nozzle of the ladle that supplies all the molten metal to the tandit shoe and controlling the casting speed. (C) Further, throughout the casting operation, said endless -
＼If the entire molten metal surface of Ruto soil is insulated and kept warm,
One-way solidification is achieved by cooling only from the belt, and sound slabs without center segregation can be produced completely continuously. However, even if segregation occurs on the surface of the slab, or the surface quality deteriorates to some extent due to shrinkage, even if it is several meters
These can be removed by simply applying a scarf of m, and subsequent rolling is possible to a certain extent; When placing it on the machine, the lower surface of the tip of the main river 7 gutter installed at exit 111 of the main river and the outer surface of the belt, and the outer surface of the side wall of the horizontal gutter tip and the inner surface of the dam block, face each other with a gap of 2 fences or less. By doing so, the rotational movement of the belt or dam block will not cause any friction with 14i, and therefore no lubrication measures are required between the two, and the rotational movement of the belt or dam block will cause the viscous molten metal to flow through the gap. 2. We have obtained the findings shown in (a,) to (d,) above that the molten metal will be attracted in the opposite direction to the intrusion, and no leakage will occur.

This invention was made based on the findings described in 1 above, and includes a horizontally disposed endless belt that is forcibly cooled from the inner surface;
The entire mold is made up of dam flocs forming side walls at both ends of the mold, and the molten metal is continuously supplied from the water gutter of the tundish, which is placed on the second side in the direction of movement of the endless belt. The molten metal is solidified by forced cooling only from the inner surface of the endless belt, while maintaining the molten metal level on the pipe, gutter, and endless belt at almost the same level, and while insulating and retaining the temperature of the molten metal surface. By advancing the belt and continuously pulling it out from the downstream side in the direction of movement of the belt, it is possible to manufacture ultra-thin slabs of excellent quality with variable thickness, and furthermore, The continuous casting machine for thin slabs is installed horizontally with an endless belt that rotates in one direction while being forcedly cooled from the inside.
It consists of a casting machine equipped with a dam block for forming side walls on both ends of the casting machine, and a tantei no. At the same time, the outer surface of the upper open mold wall of the casting machine (pv), the inner surface of the block, and the outer surface of the tip of the water gutter (1) are opposed to each other with a gap of 2 Tnm or less in total. By doing so, we are able to produce ultra-thin cast slabs of excellent quality with variable wall thickness without causing troubles such as leakage or abrasion of sliding parts.7. It is characterized by the following points.

FIG. 2 is a schematic diagram showing the state in which the continuous casting method of the present invention is carried out using the thin slab continuous casting apparatus of the present invention, and FIG. 3 is a diagram showing A-A in FIG. The cross section shows the left and right IJ being forcedly cooled from the inner surface.
-11, , 1, 1 rotates in one direction, and the endless belt 12 is disposed horizontally, and the endless belt D for forming side walls at both ends of the endless belt 12. The one-belt continuous casting machine installed in Tsuku 13 is placed in a horizontal position ((, in addition, horizontal gutter 1 is installed on the 1 hand side).
4-15, the upper open mold wall of the casting machine 1ffi'c? R-forming silent end belt 12
Thin slabs are continuously cast by arranging so that the outer surface of the block 1 and the inner surface of the block 1 and the front surface of the tip of the water slag gutter 14 are aligned with 16 gaps of 2 or less sizes. The machine is configured 1,
Therefore, when casting thin slabs, we use an endless bell l-
) After placing a dummy barque on the upper surface of 12, the molten metal 1 is supplied from the ladle 16 to the molten metal 15, and the molten metal 1 automatically flows from the horizontal gutter 14 into the mold of the υjj1~ machine ( As mentioned above, the stiffness flows into the endless belt 12 and the dam block 13 (formed by the endless belt 12 and the dam block 13). Then, at this time, remove the glue from the molten metal surface (
Preventing heat t) Knee 1~ Insulate and keep warm by covering the molten metal surface with a heat insulating material 17 to prevent solidification from progressing from the molten metal surface, and tandish 15. 1 horizontal line 1
．． 1. When the casting machine is fully operated while adjusting the molten metal supply rate etc. so that the molten metal level of each of the endless belts 12 is almost the same, the molten metal 1 of the endless belt 12 will rise from the belt side. Under forced cooling, the molten metal solidifies in one direction toward the surface of the molten metal, moves toward the bottom of the casting machine with the bell, and is smoothly sent to the conveyor pulley 7-1. In the figure, what is indicated by the reference numeral 18 is a skinmer.

In addition, since the hot water level l/bell in the tundish, horizontal gutter, and endless bell 1゜ soil is kept the same, the hot water surface does not ripple and a smooth hot water supply can be achieved. However, as shown in the schematic cross-sectional structural diagram of the slab in FIG. This makes it possible to produce a high-quality product with only a small amount of formation on the upper surface.

It's ox, the scene is inside the mold from Tantei Sosoyu (Endless Bell)
・Since the molten metal level is maintained at the same level in the tundish, changing the molten metal level in the tundish will inevitably change the molten metal level in the mold accordingly, which will affect the amount of molten metal supplied from the ladle etc. to the tundish and the casting speed. By simply controlling only
This makes it possible to make it smaller.

In the continuous casting apparatus of the present invention, a gap of 2 IN 1 or less is created between the outer surface of the tip of the horizontal gutter, the outer surface of the endless belt, and the inner surface of the cock. The rotational movement of the belt and dono block causes friction with the gutter, necessitating special lubrication measures between the two.On the other hand, if the gap exceeds 2 mm, the type of molten metal and the casting speed will be affected. In other words, there is a risk of molten metal leaking.

Of course, the method and apparatus of the present invention can be applied to both ferrous metals and non-ferrous metals, and can easily produce thin slabs of good quality in either case. Furthermore, when carrying out the method of this invention, adding a heat insulating agent is the simplest and most effective means of insulating and keeping the hot water surface warm, but it is also possible to use arc discharge or other electrical means, or to install a heat insulating cover. Whichever method is adopted (IC is also good, of course.

Next, this invention will be explained with reference to all embodiments.

EXAMPLE First, molten aluminum guild steel having the composition shown in Table 1 was made into semi-a.

Table 1 Next, using all the apparatuses 1 to 1 shown in FIG. 2, a thin steel slab was continuously cast under the following conditions.

Slab size: 50 mm thick x 1200 m + n width, Casting speed: 3 nt/min, Molten steel temperature (inside the tundish) ゛Superheat degree: 40°C, Insulating agent: Commercially available exothermic powder.

Although the gap between the tip of the gutter of the continuous casting apparatus and the bell I and dam block was set to U 2 mm, the work could be performed satisfactorily without any leakage of molten steel.

When we investigated the dimensions and properties of the slabs obtained in this way, we found that the thickness of the slabs was within the range of about 5 mm ± 5 mm, and the surface texture was slightly uneven due to the heat-generating powder. Although there were some problems, a smooth surface could be easily obtained by applying light pressure to the surface.

Furthermore, when we conducted a complete investigation of the structure of the cross section of the cast slab, we found that the structure was almost exclusively columnar crystals, as shown in Figure 4.
There was no center segregation at all.1 From the results shown above, it is clear that by producing a directionally solidified slab according to the present invention, a wide cast 11 without center segregation can be obtained with good dimensional accuracy. be.

As described above, according to the present invention, the thickness of the slab can be freely controlled, and the thickness is extremely thin (~
Industrially useful effects include the ability to easily and continuously cast high-quality slabs without center segregation in cylinders, and the production of ultra-thin metal sheets using only bucket rolling. or will be brought about.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a conventional continuous casting method, Fig. 2 is a schematic diagram showing a continuous casting method and continuous casting apparatus of the present invention, and Fig. 3 is a sectional view taken along line A-A in Fig. 2; FIG. 4 is a schematic diagram of the cross-sectional structure of a slab obtained by the method of the present invention. In the drawing, 1...Molten metal, 2...Tandish, 3.
...mold, 4 solidified shell, 5... low chevron, 6 vinyl roll, 7 conveyor table, 11... booley, 12 endless belt, 13...
...Dam block, 14...Gutter, 15...Tan tissue, 16...Gap, 17...Heat retainer, 18 Sginmar, 19...Columnar crystal, 20...Equiaxed crystal,
21 - Segregation layer. Applicant: Sumitomo Metal Industries, Ltd.

Claims (2)

[Claims] (1) A mold is constituted by a horizontally disposed endless belt that is forcibly cooled from the inner surface, and a dam block that forms side walls at both ends of the endless belt, and is disposed on the second side in the direction of movement of the endless belt. Molten metal is continuously supplied from the horizontal gutter of the tongue tissue (7), and while maintaining almost the same level of molten metal on the tongue tissue, the gutter, and the endless belt, and while performing insulation and heat retention of the area, the inner surface of the endless belt is heated. A continuous casting method for thin slabs, characterized in that the molten metal is completely solidified by forced cooling only from the side, and is continuously drawn out from the downstream side in the direction of belt movement. (2) A casting machine equipped with a horizontally disposed endless belt that rotates in one direction while being forcedly cooled from the inner surface, and dam blocks at both ends of the belt for forming the entire side wall, and the endless belt of the casting machine. a tongue tissue equipped with a horizontal gutter placed on the upper side of the movement;
A continuous casting apparatus for thin slabs, characterized in that the inner surface of the block and the outer surface of the tip of the horizontal gutter that extends to the tandei nonyu are opposed to each other with a gap of 211 II l.