JPS61249649A - Continuous casting device for thin ingot - Google Patents

Abstract

PURPOSE:To improve the surface quality of a product ingot by forming the front end of a pouring spout so as to diverge at a specific angle or below and disposing the top end of the pouring spout so as to face the specific range of a pulley part apart at a prescribed space. CONSTITUTION:The pouring spout 5 is segmented to a tundish part 9 and a spout part 7 by a skimmer 9. The part of the spout 5 where the spout faces an endless belt 2 is formed to the shape diversing at <=90 deg. angle with the moving direction of the belt. The space of <=2mm from the pulley part 1 is formed to the part where the spout faces the belt within the range of max. 1/4 circumference from the contact point between the belt 2 and the pulley 1 in the upper part thereof. A graphite layer is provided in the lower part of the space on the spout 5 side and is pressed to the belt 2. The height position of the spout part 7 is made lower than the top surface of the belt 2 by such mechanism, by which the disturbance of the surface of a molten metal 6 is prevented. The surface defect of the product is thus prevented and the surface quality thereof is improved.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a continuous casting device used to continuously cast thin slabs of good quality without defects such as pinholes and microcracks. be.

(Prior art) As a method for continuously casting thin slabs ■Special Publication No. 59-405
No. 39, ■Japanese Unexamined Patent Publication No. 59-166354, etc. are disclosed. In both of these methods, molten metal is poured onto a movable endless belt, and is cooled and solidified from the back side of the belt through the surface of the endless belt to obtain a wide thin slab.

(Problems to be Solved by the Invention) However, in the conventional method shown above, when attempting to continuously cast molten metal with a high melting point, such as molten steel, it is necessary to In the case of gutters, the thickness of the tip of the refractory should be at least 3 in terms of strength.
Since about 0 fins are necessary, when trying to obtain slabs with a thickness of 30+n or less, it is impossible to maintain the same situation between the molten steel in the planting soil and the molten steel on the endless belt. Therefore,
The molten steel flows down at the tip of the gutter, and near this flowing point, the turbulence of the scene causes the entrainment of Ar seal gas, which is captured by the slab and forms a pinhole, and the solidified shell. There is a problem in that the back surface is hit in place, which causes dents and micro-cracks on the lower surface of the slab, and furthermore, warpage of the slab occurs, making it impossible to produce a good wide thin slab.

Therefore, as shown in FIG. 1, the present inventor developed an endless belt 2 that rotates between two boobies IJLI while being forcibly cooled from the inner surface, and a belt that is arranged at both ends of the endless belt 2.
On the upstream side of the mold 4, which consists of this and a dam block 3 that rotates at the same speed, a pulley 1 is placed at the height of the tip of the gutter.
A hot water supply gutter 5 is arranged close to the top surface of the endless belt 2 which is hung thereon, and the molten metal 6 is continuously supplied from the hot water supply gutter 5 so that the molten metal 6 is placed above the hot water supply gutter 5 and the endless belt 2. Invention of a method in which even a thin slab with a thickness of 30 mm or less can be cast satisfactorily by continuously drawing out the molten metal 6 from the downstream side in the direction of movement of the endless belt while maintaining the same surface level. did.

The present invention aims to provide a continuous casting apparatus suitable for use in the above invention.

(Means for Solving the Problems) The present invention includes an endless belt that rotates between two pulleys while being forcibly cooled from the inner surface, and an endless belt that is arranged at both ends of the endless belt and rotates at the same speed as the endless belt. In a continuous casting apparatus equipped with a mold configured with a dam block and a hot water supply gutter disposed close to the upstream side of the mold, the shape of the portion of the hot water feed gutter facing the endless belt is 90 degrees in the direction of movement of the endless belt. It is formed in a shape that widens toward the end with an angle of less than 100 degrees, and the opposing part is within a maximum of 1/4 circumference from the upper contact point of the endless belt contact part of the upstream pulley, and the upper end of the opposing part is the same as the boob. There is a gap of less than 2 cranes between the
The gist is that the graphite layer is brought into contact with the endless belt so that no gaps are provided except at the upper end.

In the apparatus of the present invention, the shape of the tip of the hot water gutter 5 is adjusted to the direction of movement of the endless belt 2, as shown in FIGS. 2 and 3.
The reason why it is formed into a shape that widens toward the end with an angle of 0 degrees or less is to prevent the generated solidified shell 1) from rubbing against the tip side wall of the hot water supply gutter 5 and being pulled out, so that it is formed immediately as the endless belt 2 moves. This is to keep the tip of the hot water supply gutter 5 away from the tip.

In addition, the reason why the range facing the endless belt of the hot water supply gutter 5 is set to the maximum circumference from the upper contact point of the endless belt 2 contact part of the upstream boob I71 is that in practice, the pulley diameter is at least 60 mm.
01) Since the depth of the pool of molten metal 6 at the bridge portion 7 at the tip of the water supply gutter 5 is approximately 300 mm at the above position,
This is because approximately mW can be secured and no power exceeding 1/4 of the circumference is required. This is also because when the circumference exceeds the % circumference, the surface of the gutter refractory facing the pulley 1 comes to surround the boo I71, and the shape gradually becomes complicated.

Furthermore, the upper end of the tip of the hot water supply gutter 5 is connected to the endless belt 2 by 2.
The reason for the gap being less than m is that if there is no gap, friction will occur between the transfer half of the endless belt 2 and the tip of the hot water supply gutter 5, requiring special lubrication measures between the two. This is because if it exceeds the limit, depending on the type of molten metal 6 and the casting speed, there is a risk that the molten metal 6 may become inserted.

By the way, the hot water supply gutter 5 may be formed using the same material as shown in FIG. 2, or may be formed using a graphite layer 8 as shown in FIG.
A protruding one is used.

In the case shown in Fig. 2, if a high melting point metal such as steel is to be cast, the material of the machine part 7 of the hot water supply gutter 5 is mainly oxidized, such as fused silica, A#203, ZrO2, MgO, etc. Physical refractories will be used, but although there are differences in degree depending on the material and shape,
High temperature creep deformation occurs due to the weight of the molten metal and its own weight. Therefore, if casting continues for a long time, it may become impossible to maintain the gap of 2 cranes or less.

In order to prevent this, the graphite layer 8 is brought into contact with the endless belt 2 to support the high-temperature creep deformation of the gutter refractory, and the good lubricity of graphite allows the bridge portion 7 to and the endless belt 2,
It is intended to protect bridge section 7 from damage.

By the way, it is possible to provide this graphite layer 8 up to the upper end of the tip of the gutter, but in this case graphite has a high thermal conductivity,
A solidified shell 1) is formed therefrom, and a slab with good surface quality cannot be obtained due to instability when the graphite layer 8 and solidified shell 1) are separated. Further, in the case of a material that reacts with graphite such as molten steel, the graphite layer 8 gradually melts away and becomes useless, so the upper end of the tip of the bridge portion 7 was made without the graphite layer 8.

It goes without saying that there is no problem with the casting shown in Fig. 2 if the casting time is short, even in the case of low melting point metals or high melting point metals. It is also possible to lengthen the casting time by covering with skin.

In addition, in FIGS. 2 and 3, 9 indicates a tundish portion, and 10 indicates a skimmer.

(Example) A boo IJ 1 with a diameter of 600 mm on which an endless belt 2 made of mild steel with a thickness of 1.4n+ is hung, a dam block 3 made of copper with a height of 30 mm, and a bridge part 7 made of fused silica. Molten steel having the composition shown in the table below is cast into the continuous casting device shown in Fig. 1, which is composed of a hot water supply gutter 5 with a pool depth of 40mm, and a wide thin casting with a thickness of 5Iu and a width of 600+n. It was decided to obtain the pieces continuously at a speed of 40 m/win.

In this example, the hot water supply gutter 5 shown in FIGS. 2 and 3 was used, and was cast by disposing it facing the endless belt 2 with a gap of 21 m.

When the hot water supply gutter 5 shown in FIG. 3 was used, a good test operation could be carried out for about 3 hours. Here, the reason why the casting was completed in 3 hours was because the ladle capacity was small and the molten steel ran out; it was determined that if the ladle capacity was large, it would be possible to continue casting for a longer period of time.

Also, when using the hot water gutter 5 shown in Fig. 2, approximately 300
Good test operations were carried out for several minutes.

In addition, in this experiment, the tandish part 9, the bridge part 7,
The level of the endless belt 2 was controlled by adjusting the amount of hot water supplied to the tundish part 9 by measuring the level of hot water in the tundish part 9 with a laser displacement meter.

(Effects of the Invention) As described above, by using the apparatus of the present invention, wide thin slabs with good surface properties can be continuously cast.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing an embodiment of a continuous casting apparatus according to the present invention, Fig. 2 is a perspective view showing a first embodiment of a hot water supply gutter which is a component part thereof, and Fig. A perspective view showing an embodiment, and the opening of FIG. 3 is a similar enlarged sectional view. 1 is a pulley, 2 is an endless belt, 3 is a dam block, 4 is a mold, 5 is a hot water supply gutter, 7 is a bridge part, and 8 is a graphite layer. Figure 1 Figure 2.

Claims (1)

[Claims] (1) A mold consisting of an endless belt that rotates between two pulleys while being forcibly cooled from the inner surface, and dam blocks that are placed at both ends of the endless belt and rotate at the same speed as the endless belt; In a continuous casting apparatus equipped with a hot water supply gutter disposed close to the upstream side of the mold, the shape of the portion of the hot water feed gutter facing the endless belt is 9 times the same as the direction of movement of the endless belt.
It is formed in a shape that widens toward the end with an angle of 0 degrees or less, and the opposing portion is within a maximum of 1/4 circumference from the upper contact point of the endless belt contact portion of the upstream pulley, and at least the upper end of the opposing portion is A continuous casting apparatus for thin slabs, characterized in that a graphite layer is brought into contact with the endless belt so that there is a gap of 2 mm or less with respect to the endless belt, and there is no gap other than the upper end of the opposing part.