JPH09192789A - Belt type continuous casting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain deformation of a belt by efficiently preheating the casting belts advanced to a mold zone, in a belt type continuous casting method, continuously producing a thin sheet-like cast slab by supplying molten metal into the mold formed with pair of the casting belts. SOLUTION: The inner part of the mold formed with the pair of casting belts 2 is divided into a cooling zone CZ at the upstream side and a preheating zone PZ at the downstream side. In the cooling zone CZ, the cooling of the casting belts 2 is executed by using cooling water injection nozzles 3 and the fin rolls 4. On the other hand, in the preheating zone PZ, the cooling is not executed and the casting belts 2 are pushed to the cast slab S by using the backup rolls 5 and heated with the heat thereof and the temp. of the pair of the casting belts 2 is raised in the preheating zone PZ in the mold. Therefore, the casting belts advanced to the mold zone are efficiently preheated without adding a special heating mechanism and the energy and therefore, the belt deformation is restrained and the quality of the cast slab can be stabilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt-type continuous casting method for continuously casting thin plate-shaped slabs.

[0002]

2. Description of the Related Art In belt-type continuous casting in which thin plate-shaped slabs such as thin slabs are cast by a mold formed by a pair of casting belts, the casting belt is deformed during casting due to cracks or dents on the slab surface. Since it causes deterioration of the surface properties such as, the prevention of the deformation is an extremely important issue. Here, some of the deformations of the casting belt occur immediately after the casting belt pivots and enters the mold area. That is, the casting belt that has entered the mold region is forcibly cooled from the back side with cooling water or the like, and the contact surface with the molten metal becomes higher in temperature than the cooled back side, so that the belt warps with the high temperature side as the upper part, In the plane of the belt, a portion that does not come into contact with the molten metal restrains thermal expansion of the portion that comes into contact with the molten metal, so that distortion occurs in the belt.

Therefore, prevention of belt deformation in these belt type continuous castings has been studied from various directions. For example, in the continuous casting method disclosed in Japanese Patent Publication No. 57-61502, the casting belt is rotated. Before reaching the entrance of the casting area, the temperature of the rotating casting belt is raised to suppress belt deformation in the casting area. [FIG. 5] is a front cross-sectional view schematically showing a schematic configuration of a belt type continuous casting machine in the above casting method (Japanese Patent Publication No. 57-61502). In this casting method, as shown in [Figure A], the immersion nozzle (31a) of the tundish (31) is placed in a mold formed by a pair of casting belts (22) that are rotated by front and rear pulleys (21). While supplying molten metal (M) from the cooling belt, the cooling water jet nozzles (23) are lined up on the back side of the casting belts (22).
By cooling the casting belts (22) in the casting area with the fin rolls (24), the molten metal (M) is sequentially solidified in the moving process to continuously produce thin plate-shaped slabs (S). Also, one or a plurality of banks (5) equipped with a powerful infrared heater (25a) around the pulley (21) located upstream thereof.
5) is provided, and the casting belt (22) moving in front of and around the pulley (21) on the inlet side of the casting area by this bank (25)
Heat is applied to a certain range of the surface of the casting belt (22) to increase the temperature of each casting belt (22) before it comes into contact with the molten metal (M) in the casting area, thereby suppressing belt deformation in the casting area.
As still another method, heating fluid such as steam is fed into the deep groove of the outer circumference of the pulley on the inlet side of the casting area, without the hollow portion, and heat is applied to the casting belt moving around the pulley. A method of increasing the temperature of each casting belt before it contacts the molten metal is also adopted.

[0004]

However, in the above conventional casting method, the casting belt is preheated before coming into contact with the molten metal, so that the temperature of the portion in the plane of the belt which does not come into contact with the molten metal and the portion which comes into contact therewith. Although it is possible to suppress the distortion of the casting belt by suppressing the gradient low, there is a problem that the mechanism of the belt continuous casting machine to be applied becomes complicated and the device manufacturing cost increases, and the maintenance load increases and running cost increases. is there.

The present invention is intended to solve the above-mentioned problems of the prior art. A pair of casting belts that rotate to the upstream side and re-enter the casting mold area after casting in the casting mold area have a special heating mechanism. A belt-type continuous casting method that can efficiently preheat and increase the temperature at the time of contact with molten metal to suppress belt deformation without adding energy and energy, and thus economically achieve stable slab quality. For the purpose of provision.

[0006]

In order to achieve the above object, the present invention has the following arrangement. That is, the belt-type continuous casting method according to the present invention is a pair of casting belts that are arranged parallel to each other and that rotate endlessly so that mutually facing surfaces move in the same direction, and this pair of casting belts. In the mold formed by a pair of side dams arranged on both sides of the facing portion of the pair and moving in synchronization with the casting belt, molten metal is supplied from the upstream end portion in the moving direction of the pair of casting belts and moved. The belt-type continuous casting method in which thin casting slabs are continuously produced by cooling the casting belts from the back surface side while contacting the facing surfaces of the pair of casting belts and continuously solidifying the molten metal in the moving process. At
The mold is divided into an upstream side cooling region and a downstream side preheating region, while cooling the casting belt in the cooling region,
The casting belt is not cooled in the preheating region, and the pair of casting belts are pressed against the slab by using a backup roll to heat the slab by the heat of the slab, thereby increasing the temperature of the pair of casting belts in the preheating region. Characterize.

Further, between the cooling area and the preheating area in the mold, a selective cooling area for cooling and stopping the cooling of the casting belt is provided independently of the cooling area, and the casting belt is cooled in the cooling area. On the other hand, in the selective cooling region, the cooling of the casting belt and the cooling stop may be selectively performed in the selective cooling region according to the casting conditions of the slab.

Further, a temperature sensor for measuring the temperature of the pair of casting belts is arranged between the selective cooling area and the preheating area, and 0N / 0FF of cooling in the selective cooling area is controlled according to the output of the temperature sensor. It may be treated as something.

In the above belt type continuous casting method of the present invention,
Formed by a pair of casting belts that are arranged in parallel and rotate endlessly so that the opposite surfaces move in the same direction, and a pair of side dams that are arranged on both sides of the facing portions of the pair of casting belts and move in synchronization The casting mold is divided into an upstream cooling area and a downstream preheating area, and the casting belt is cooled in the upstream cooling area, so the molten metal supplied from the upstream end into the casting mold. Can be sequentially solidified in the moving process to continuously produce thin plate-shaped slabs. Further, in the preheating region on the downstream side, the casting belt is not cooled, and each pair of casting belts is pressed against a slab by a backup roll to be heated by the heat of the slab, and the pair of casting belts in the preheating region Since the temperature is increased, the temperature of the pair of casting belts that rotate to the upstream side and enter the mold region again after casting in the mold region is efficiently preheated without adding a special heating mechanism or energy. The belt deformation can be suppressed by increasing the temperature at the time of contact with the molten metal.

Further, between the cooling area and the preheating area in the mold, there is provided a selective cooling area capable of cooling and stopping the cooling of the casting belt independently of the cooling area. While always cooling, in the subsequent selective cooling area, it is possible to easily respond to changes in casting conditions such as casting speed and slab size by selectively cooling and stopping the casting belt according to the casting conditions of the slab. As a result, stable continuous casting can be performed. That is, the cooling of the casting belt in the selective cooling region is selected according to the casting conditions such as the casting speed and the slab size, that is, the cooling is performed when the casting speed is increased or a large sized slab is cast. On the contrary, in the case of slowing the casting speed or casting a small-sized slab, by stopping the cooling, it is possible to easily respond to changes in the casting conditions with the same device configuration and stabilize the operation. Continuous casting can be performed.

A temperature sensor for measuring the temperature of the pair of casting belts is arranged between the selective cooling area and the preheating area, and 0N / 0FF of cooling in the selective cooling area is controlled according to the output of the temperature sensor. By doing so, it is possible to automatically adjust the cooling conditions of the casting belt in response to fluctuations in the cooling state of the slab, and to perform stable continuous casting.This also enables casting conditions such as casting speed and slab size. Can be easily changed.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. [FIG. 1] is a front sectional view schematically showing a schematic configuration of a continuous casting machine used in the first embodiment of the present invention. It should be noted that this continuous casting machine adopts a vertical casting method in which molten metal is supplied from above and slabs are sent from below.

In the vertical continuous casting machine of this embodiment shown in FIG. 1, the upper and lower pulleys are arranged so as to face each other and are parallel to each other in the vertical direction, and the mutually facing surfaces move in the same vertical downward direction.
A pair of casting belts (2) that can be rotated by (1), and the casting belts that are arranged on both sides of the facing portion of the pair of casting belts (2).
In the mold formed by a pair of side dams (not shown) that move in synchronization with (2), the molten metal (M) is supplied from the immersion nozzle (10a) of the tundish (10) arranged above it. The molten metal (M) is sequentially solidified in the moving process by contacting the facing surfaces of the pair of casting belts (2) moving downward, and continuously producing thin plate-shaped slabs (S).

On the other hand, in the mold, the cooling area (C
Z) and the preheating zone (PZ) on the downstream side, and in the cooling zone (CZ), a plurality of cooling elements alternately arranged on the back surface side of the casting belt (2) in the cooling zone (CZ). The water jet nozzles (3) and the fin rolls (4) cool the casting belts (2) to accelerate the solidification of the molten metal (M) in contact with the casting belts (2). In the subsequent preheating zone (PZ) on the downstream side, on the back side of the casting belt (2) in the preheating zone (PZ), instead of the cooling water jet nozzle (3) and the fin roll (4), the outer periphery is formed. A backup belt (5) with a large number of grooves around it to secure the flow path for cooling water
(2) is not cooled, but the pair of casting belts (2) are pressed against the inner slab (S) by the backup rolls (5) and heated by the heat of the slab (S),
In the cooling zone (CZ), the temperature of the casting belt (2) cooled in the upstream cooling zone (CZ) is raised.

FIG. 2 is a front sectional view schematically showing the schematic construction of another continuous casting machine used in the first embodiment of the present invention. This continuous casting machine adopts a horizontal casting method in which molten metal is supplied from one side and slabs are sent from the other one side, except that the casting direction is different [Fig. 1].
Since it is the same as that of the vertical continuous casting machine shown in FIG. 1, the same parts as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. Only the differences will be summarized.

In the horizontal continuous casting machine according to the present embodiment shown in FIG. 2, the pair of casting belts (2) forming the mold are inclined so that the surfaces facing each other are in the horizontal direction and the upstream side is in the high position. It is distributed. Then, an injection type immersion nozzle (11a) protruding from the side of the tundish (11) arranged on the upstream side thereof.
The molten metal (M) is supplied from the
(M) is sequentially solidified in the moving process to continuously produce thin plate-shaped slabs (S). Further, in the same manner as described above, in the cooling zone (CZ) in the mold, the molten metal is cooled by cooling each casting belt (2).
(M) promotes solidification while continuing to the downstream preheating region (P
In Z), the casting belts (2) are not cooled, but the temperature of the casting belts (2) cooled in the upstream cooling zone (CZ) is increased by the heat of the slab (S).

In the present embodiment, the continuous casting of the Al alloy slab was carried out by using the two continuous casting machines having the above construction. The casting conditions are as shown in [Table 1]. Here, the lengths of the cooling zone (CZ) and the preheating zone (PZ) in the mold were determined by heat transfer calculation and set. For comparison, continuous casting of the same Al alloy thin slab was performed using conventional vertical and horizontal continuous casting machines that cool the casting belt over the entire casting area. Then, in these castings, the amount of deformation of the casting belt and the temperature of the casting belt immediately before entering the mold region were measured with a contact thermometer, and the surface properties of the obtained slab were examined. The results are shown in [Table 2].

[0018]

[Table 1]

[0019]

[Table 2]

As shown in [Table 2], in the comparative example, the temperature of the casting belt immediately before entering the casting mold region was cooled in the entire casting mold region, so that the temperature was considerably low even under the same conditions such as casting speed. In contrast, in this implementation, the vertical type
It was confirmed that both horizontal types were preheated to about 110 ℃. Further, in the present embodiment in which the casting belt was preheated in the preheating region in the mold, the belt deformation amount was smaller than that of the comparative example in which the preheating was not performed, and the surface quality of the obtained slab was good.

Here, what was of concern when applying the method of the present invention was the deterioration of the surface property due to so-called perspiration, which is caused by the reheating of the surface of the slab in the preheating region in the mold. No perspiration was observed on the surface of the slabs obtained in the examples, so that if the lengths of the cooling region and the preheating region in the mold were carefully and appropriately selected, the cooling was stopped on the downstream side of the mold region. It was confirmed that sweating did not occur. Further, the surface texture of the slab obtained in this example, even compared to the slab obtained by the prior art of preheating the casting belt immediately before entering the mold region with an infrared heater,
There is no difference, and the amount of cooling water used and power consumption of this embodiment are much smaller than those used in the above-mentioned comparative example that uses the conventional cooling method and the above-mentioned conventional casting using the infrared heater. It is. Then, from these results, by preheating the casting belt by the heat of the slab on the downstream side of the mold region, without adding a special heating mechanism or energy, when entering the mold region and contacting the molten metal It was possible to confirm the excellent effect of the present invention for suppressing the belt deformation by increasing the temperature.

In the continuous casting machine of the above embodiment, a roll having a large number of grooves on its outer circumference was used as the backup roller in the preheating region, but this backup roller may be a flat roll without grooves. . Further, as the cooling means for the casting belt in the cooling region, the cooling water jet nozzle and the fin roll are used, but this is an example, and if the casting belt can be effectively cooled from the back surface side,
For example, it goes without saying that a cooling pad having a cooling water channel inside may be used.

FIG. 3 is a front sectional view schematically showing a schematic configuration of a vertical continuous casting machine according to a second embodiment of the present invention. The vertical continuous casting machine of this embodiment is the same as the vertical continuous casting machine of the first embodiment shown in FIG. 1 except that the cooling structure in the mold is different by 1 part. Here, the same reference numerals are given to the respective parts equivalent to [FIG. 1], the description thereof will be omitted, and only the difference will be summarized and described.

In the horizontal continuous casting machine of this embodiment shown in FIG. 3, a selective cooling zone (SZ) is provided between the cooling zone (CZ) and the preheating zone (PZ) in the mold, and this selective cooling is further conducted. A temperature sensor (6) for measuring the temperature of the casting belt (2) is arranged between the zone (SZ) and the preheating zone (PZ). Then, in the cooling zone (CZ) on the upstream side in the mold, a cooling pad having a cooling water passage inside is provided.
A plurality of (7) are arranged, and the casting pad (2) in the cooling zone (CZ) is cooled from the back surface side at an appropriate time by the cooling pads (7). On the other hand, its cooling area (C
In the selective cooling zone (SZ) following Z), the cooling pad (7 ') which receives the supply of the cooling water under the control system (not shown) independent of the cooling pad (7) of the cooling zone (CZ). Are arranged, and the casting belt (2) in the selective cooling area (SZ) is cooled from the back surface side at an arbitrary time by the cooling pads (7 ′). Furthermore, the cooling pad of this selective cooling area (SZ)
The control system of (7 ') is connected to the temperature sensor (6),
According to the output of the temperature sensor (6), the selective cooling area (S
It is supposed to control 0N / 0FF of the cooling water supply to the cooling pad (7 ') of Z).

FIG. 4 is a front sectional view schematically showing a schematic configuration of a horizontal continuous casting machine according to a third embodiment of the present invention. The vertical continuous casting machine of this embodiment is the same as the horizontal continuous casting machine of the first embodiment shown in FIG. 2 except that the cooling structure in the mold is partly different. The same reference numerals are given to the respective parts equivalent to those in FIG. 1, and the description thereof will be omitted. Only the differences will be summarized and described.

In the horizontal continuous casting machine of this embodiment shown in FIG. 4, a selective cooling zone (SZ) is provided between the cooling zone (CZ) and the preheating zone (PZ) in the mold, and further this selective cooling is performed. A temperature sensor (6) for measuring the temperature of the casting belt (2) is arranged between the zone (SZ) and the preheating zone (PZ). Then, as in the vertical continuous casting machine of the third embodiment, the upstream cooling region (C
In Z), the casting belt (2) in the cooling zone (CZ) is constantly cooled by a plurality of cooling pads (7) arranged on the back surface side, while in the subsequent selective cooling zone (SZ), the back surface side. 0N of cooling water supply according to the output of the temperature sensor
/ 0FF can be cooled at any time by a controlled cooling pad (7 ').

In the vertical and horizontal continuous casting machines of the second and third embodiments, the casting belt is preheated by the heat of the slab in the downstream preheating region as in the continuous casting of the first embodiment. It is possible to suppress belt deformation by increasing the temperature of the casting belt when entering the mold region and coming into contact with the molten metal. Further, while the casting belt is always cooled in the upstream cooling area, the casting belt is cooled / stopped selectively in the subsequent selective cooling area according to the casting conditions of the slab, that is, the casting speed is increased. Cooling is performed when speeding up or casting a large size slab, and conversely, when cooling the casting speed slower or when casting a small size slab, the cooling is stopped. Stable continuous casting can be performed by easily adapting to changing conditions.
In addition, by measuring the temperature of the casting belt toward the preheating region on the downstream side and controlling 0N / 0FF of cooling in the selective cooling region based on the measured value, casting in response to fluctuations in the cooling state of the slab It is possible to automatically adjust the belt cooling conditions to perform more stable continuous casting, and to easily change casting conditions such as casting speed and slab size.

In the vertical and horizontal continuous casting machines of the third and fourth embodiments, a cooling pad having a cooling water passage therein is used as a cooling means for the casting belt in the cooling area and the selective cooling area. However, this is an example, and if the casting belt can be effectively cooled from the back surface side, for example, cooling water injection similar to that of the vertical and horizontal continuous casting machines in the first embodiment can be performed. It goes without saying that nozzles and fin rolls may be used.

[0029]

As described above, according to the belt type continuous casting method according to the present invention, a pair of casting belts that rotate to the upstream side after casting in the casting mold region and enter the casting mold region again, Without adding special heating mechanism or energy,
It is possible to suppress the belt deformation by efficiently preheating and increasing the temperature at the time of contact with the molten metal, so that the quality of the cast piece can be stabilized economically.

[Brief description of the drawings]

FIG. 1 is a front sectional view schematically showing a schematic configuration of a vertical continuous casting machine used in a first embodiment of the present invention.

FIG. 2 is a front sectional view schematically showing a schematic configuration of another horizontal continuous casting machine used in the first embodiment of the present invention.

FIG. 3 is a front sectional view schematically showing a schematic configuration of a vertical continuous casting machine according to a second embodiment of the present invention.

FIG. 4 is a front sectional view schematically showing a schematic configuration of a horizontal continuous casting machine according to a third embodiment of the present invention.

FIG. 5 is a front sectional view schematically showing a schematic configuration of a conventional belt type continuous casting machine.

[Explanation of symbols]

(1) --Pulley, (2) --Casting belt, (3) --Cooling water injection nozzle, (4) --Fin roll, (5) --Backup roll, (6) --Temperature sensor, ( 7)-Cooling pad, (7 ')-Cooling pad, (10)-Tundish, (10a)-Immersion nozzle,
(11)-Tundish, (11a)-immersion nozzle, (CZ)-cooling zone, (PZ)-preheat zone, (SZ)-selective cooling zone, (M)-molten metal, (S ) --Slab.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location B22D 11/22 B22D 11/22 A

Claims (3)

[Claims] 1. A pair of casting belts, which are opposed to each other in parallel and rotate endlessly so that mutually opposing surfaces move in the same direction. In the mold formed by the casting belt and a pair of side dams that move in synchronization with each other, molten metal is supplied from an upstream end in the moving direction of the pair of casting belts, and the facing surfaces of the pair of casting belts move. In the belt-type continuous casting method, in which the casting belt is cooled from the back side, and the molten metal is sequentially solidified in the moving process to continuously produce thin plate-shaped slabs while being brought into contact with It is divided into a cooling region and a preheating region on the downstream side, and the casting belt is cooled in the cooling region, while the casting belt is not cooled in the preheating region, and each pair of casting belts is cast using a backup roll. A belt-type continuous casting method, which comprises pressing against a piece to heat it with the heat of the slab to raise the temperature of a pair of casting belts in the preheating region. 2. A selective cooling region capable of cooling and stopping the cooling of the casting belt independently of the cooling region is provided between the cooling region and the preheating region in the mold, and the casting belt is cooled in the cooling region. The belt-type continuous casting method according to claim 1, wherein the casting belt is selectively cooled and stopped in accordance with the casting conditions of the slab in the selective cooling region while the cooling is continuously performed. 3. A temperature sensor for measuring the temperature of a pair of casting belts is arranged between the selective cooling region and the preheating region, and 0N / 0FF of cooling in the selective cooling region is controlled according to the output of the temperature sensor. The belt type continuous casting method according to claim 2.