JPH07112608B2 - Belt type continuous casting method and apparatus for thin metal plate - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for continuously casting a thin metal plate such as a steel strip by cooling and solidifying a molten metal on an endless belt which runs horizontally or tilts upward.

[0002]

2. Description of the Related Art The inventors of the present invention poured molten steel, for example, onto an inclined endless belt, cooled and solidified on the endless belt to form a shell, and then pulled out a slab from the upper side of the inclined belt to cast a thin steel sheet. The method was disclosed and disclosed in JP-A-58-90357, JP-A-59-156554, JP-A-62-16851 and the like. Furthermore, in order to prevent the deterioration of the surface properties of the cast thin plate, we propose a method to prevent the remelting of the solidified shell at the molten steel injection point by providing a porous refractory at the molten metal injection port of the tundish to reduce the molten metal flow rate. Yes
61-78538 publication).

[0003]

However, the above-described technique of providing a porous refractory material at the molten metal injection port cannot sufficiently suppress the speed of the molten steel injection flow, and the formed solidified shell is slightly remelted. There is a problem that the thickness becomes non-uniform in the width direction, and further, as the casting time elapses, inclusions adhere to the porous portion of the refractory and become clogged, and the molten metal flow deteriorates.

The present invention solves such a problem and forms a solidified shell having a uniform thickness in the width direction regardless of casting time,
The purpose of the present invention is to cast a slab having a good surface quality without wrinkles.

[0005]

The present invention provides the following casting method in order to achieve such an object. That is, in the method for continuously casting a thin metal plate by injecting a molten metal onto an endless belt that travels horizontally or upwardly inclined according to the present invention to cool and solidify the molten metal, a molten metal storage container for storing the molten metal. Characterized by a casting method in which the molten metal in the molten metal and the molten metal in the molten metal pool are communicated with each other by a siphon type pouring device, and the molten metal reservoir is filled with a predetermined amount of molten metal by changing the water level in the molten metal storage container. It is possible to make the flow velocity of the molten metal into the molten metal pool extremely small.

[0006]

In general, when the molten metal is injected from the molten metal supply port into the molten metal pool, the relationship between the molten metal flow rate u and the molten metal pressure difference ΔP is as follows.

[0007]

[Equation 1]

However, ρ: density, K: proportional constant Therefore, the larger the flow velocity u, the larger the pressure difference ΔP. In the conventional drop injection type inclined belt casting method, the supplied molten metal falls and collides with the surface of the solidified shell on which it is formed.However, when the pressure difference becomes large, the impact on the shell surface becomes large, and the impact causes the solidification. The shell redissolves. Therefore, only the portion corresponding to the molten metal supply port is redissolved in the width direction of the solidified shell, and unevenness is formed on the shell surface.

As described above, once the unevenness is formed,
Even after a thin plate having a predetermined thickness is formed, unevenness remains on the surface, and even if it is corrected by a rolling roll, the thin plate surface is distorted, which adversely affects the surface properties. On the other hand, the supply amount m of the molten metal is obtained by the following formula based on the width b of the thin plate, the thickness d and the feeding speed v.

M = ρdbv (2) Therefore, when casting a thin plate of a predetermined size in a predetermined time, a fixed amount of melt supply m is required. Further, such a molten metal supply amount m is obtained by the following formula by the injection speed u and the area S of the molten metal supply port.

[0011]

[Equation 2]

From the above, in order to reduce the molten metal injection speed u in order to reduce the molten metal pressure difference ΔP, the molten metal supply amount m is constant, so that the area S needs to be increased from the equation (3). . The present invention provides a molten metal supply method and apparatus capable of decreasing the molten metal injection speed u and increasing the molten metal supply port area S.

[0013]

The present invention will be described in detail below based on one embodiment. FIG. 1 is a partial cross-sectional side view schematically showing an inclined belt type continuous casting apparatus for carrying out the method of the present invention. First,
The configuration of the continuous casting machine 1 will be described. In the figure, a metal endless belt 4 is wound around a pair of pulleys 2 and 3, and the pulley 3 is arranged at the same height as the pulley 2 or at a position higher than the pulley 2, so that the endless belt 4 is a pulley. It is configured to be horizontal or rise toward 3. A plurality of heat resistant blocks 5 connected by chains or the like are arranged on both side surfaces of the endless belt 4, and these heat resistant blocks 5 are configured to move in synchronization with the running of the belt 4. The heat-resistant block 5 that partitions both side surfaces on the upper side where the belt 4 travels in a straight line forms a side weir 5-1 and the rear surface weir 7 partitions the belt 4 in the width direction. A basin 6 is formed whose only opening is open. A cooling device 11 is provided on the back side of the belt 4 corresponding to the pool portion 6. The cooling device includes a plurality of rolls 13 that are in contact with and support the back surface of the belt 4, and a cooling nozzle that is located between the rolls and that injects a coolant that cools the belt 4.
14 and.

Next, the pouring device of the present invention will be described. The siphon type pouring device 8 is arranged above the pouring portion 6, and the pouring device is provided with a molten metal suction port 8-1 which is immersed in the molten metal 9 stored in the molten metal container 10. , A connecting pipe 8-2 and a molten metal supply port 8-3 which is immersed in the molten metal 9 of the molten metal pool portion 6. The molten metal supply port 8-3 is largely opened in the width direction of the belt 4, and the molten metal storage container 10 adjusts the flow rate of the molten metal via the water level of the molten metal so that the molten metal can be moved up and down. (Not shown). Further, in place of the drive mechanism, a pump mechanism for enclosing an inert gas and adjusting the pressure inside the molten metal container may be provided.

In the above apparatus, the position of the molten metal container 10 is determined according to the above equation (3) to set the water level of the molten metal in the container, and the molten metal suction port 8-
1, and the molten metal supply port 8-3 through the connecting pipe 8-2.
The molten metal is supplied to the pool 6 from the molten metal. Since the molten metal is supplied by the siphon method in this manner, the flow rate u of the molten metal can be made extremely small, and since the molten metal supply port 8-3 is wide open in the belt width direction, a desired amount of molten metal can be secured. it can.

The molten metal 9 poured into the pool 6 is a cooling device.
Heat is removed by 11 and cooled / solidified to form shell 12. The solidified shell 12 is conveyed rightward in FIG. 1 as the belt 4 moves. Since heat removal continues during this transportation process,
The solidified shell 12 grows into a thin metal plate 15 having a predetermined thickness,
It is sent out from the pool 6 and separated from the upper surface of the belt 4, then rolled down by a rolling roll 16 and wound as a coil 18 by a winder 17.

According to the present invention, since the molten metal flow rate into the molten metal pool 6 can be made extremely small, re-melting of the solidified shell immediately below the molten metal supply port can be prevented, whereby a metal having a uniform thickness across the width direction. Sheets can be manufactured. (Example) With a continuous casting machine shown in FIG. 1, a slab width of 600 m
Molten steel was cast under the conditions of m, pool length on belt 3 m, casting speed 8 m / min, average slab thickness 15 mm.

The injection flow control is carried out by the two methods of the present invention, namely, (1)
Pressure adjustment method (2) Using a vertical movement method of an injection container, injection was performed in each method so as to keep the level of the molten metal on the belt pool constant, to manufacture a thin steel sheet. Further, as a comparative example, a thin steel sheet was manufactured under the same conditions as above by a conventional method of pouring molten metal from a pouring device into a molten metal pool in a dropping manner.

As a result of the casting, as shown in Table 1, the variation in the thickness in the width direction (the state of the casting or the like) of the slab produced by the method of the present invention was remarkably reduced.

[0020]

[Table 1]

[0021]

As described above, according to the present invention,
Since the flow velocity of the molten metal can be made extremely low and the molten metal can be poured into the pool, a solidified shell with a uniform thickness can be formed in the belt width direction, which prevents deterioration of the surface properties of the cast thin plate, It is possible to manufacture a thin metal plate having excellent properties.

[Brief description of drawings]

1 is a schematic partial cross-sectional side view of an apparatus for carrying out the method of the present invention.

[Explanation of symbols]

 1 ... Inclined belt type continuous casting machine 2, 3 ... Pulley 4 ... Endless belt 5 ... Heat resistant block 6 ... Hot water pool portion 7 ... Rear weir 8 ... Siphon type pouring device 9 ... Molten metal 10 ... Molten metal container 11 ... Cooling device 12 … Solidification shell 13… Roll 14… Cooling nozzle 15… Metal sheet 16… Rolling roll 17… Winding machine 18… Coil

Claims (6)

[Claims] 1. A molten metal pool is formed by providing a rear surface weir and a heat-resistant block on an endless belt that runs horizontally or inclined upward, and a molten metal is poured into the molten metal pool to cool and solidify the molten metal. In the method for continuously casting a thin metal plate by connecting the molten metal in the molten metal storage container for storing the molten metal and the molten metal in the molten metal reservoir with a siphon type pouring device,
Then, the inclined belt type continuous casting method for a thin metal plate, characterized in that the molten metal reservoir is filled with a predetermined amount of molten metal by changing the water level in the molten metal container. 2. The method according to claim 1, wherein the flow rate of the molten metal to the molten metal pool is adjusted by moving the molten metal container up and down. 3. The method according to claim 1, wherein the flow rate of the molten metal to the molten metal reservoir is adjusted by adjusting the pressure in the molten metal container. 4. A molten metal pool is formed by providing a rear weir and a heat-resistant block on an endless belt which runs horizontally or inclined upward, and a molten metal is poured into the molten metal pool to cool and solidify the molten metal. Thus, in a device for continuously casting thin metal plates, the inside of the molten metal storage container for storing the molten metal is connected to the molten metal reservoir through a siphon type pouring device, and the molten metal is supplied to the siphon type pouring device. An inclined belt type continuous casting apparatus for a thin metal plate, characterized in that a mouth is opened in the width direction of the endless belt. 5. The apparatus according to claim 4, wherein the molten metal storage container is provided with a vertical movement mechanism. 6. The apparatus according to claim 4, wherein the molten metal storage container is provided with an in-vessel pressure adjusting device.