JPH067899A - Slab continuous casting machine and continuous casting method - Google Patents

Abstract

(57) [Summary] [Purpose] There is little segregation or non-metallic inclusions inside, and plate thickness is 3
Provided are a continuous casting machine and a continuous casting method capable of producing a slab having a thickness of 00 mm or more. A metal belt, whose back surface is cooled by water and runs laterally, and a secondary cooling zone having a large number of rollers and cooling water jet nozzles are connected in the running direction of the metal belt. A pair of side wall dams that run in synchronization with the metal belt are provided across the metal belt and the secondary cooling zone. Further, a molten metal supply tank having a gutter and a hot water storage part is arranged so that the end part of the gutter is in close contact with the metal belt and the side weir between the side weirs on the inlet side of the metal belt. The molten metal is poured into the molten metal storage portion, and a molten metal reservoir in communication with the molten metal in the molten metal supply tank is formed on the metal belt. A solidified shell is generated on the metal belt, and the solidified shell is allowed to grow following the running of the metal belt while running, and solidification is completed in the secondary cooling zone to form a slab.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has a plate thickness of 50 mm or more,
Particularly, the present invention relates to a continuous casting machine and a continuous casting method capable of producing a thick slab having a segregation and non-metallic inclusions of 300 mm or more.

[0002]

2. Description of the Related Art For example, as a method for producing a thick slab having a thickness of 300 mm or more, a usual ingot making method can be considered.
However, the steel ingot produced by the ingot making method has problems that it has segregation of components, its cleanliness is insufficient, and that it needs a slabbing step to form a thick slab of a desired size, resulting in a low yield.

Japanese Patent Publication No. 53-19290, Japanese Patent Laid-Open No. Sho 6
The invention of 1-14067 relates to the production of thick slabs,
The molten metal is poured into the flat mold, and solidification is grown vertically upward from the bottom surface of the mold to reduce segregation. According to these methods, the bottom surface of the flat mold is formed by an ordinary platen, but the cooling rate of the molten metal cannot be adjusted by an ordinary platen without forced cooling. Therefore, in the case of a thick slab, the solidification rate from the bottom is slow in the upper part of the mold, it is easy to solidify from the top to the bottom, it is possible to accurately grow the solidification vertically upward from the bottom of the mold. difficult.

[0004]

When the solidification is allowed to grow upward from the bottom surface to prevent segregation components and non-metallic inclusions from being trapped in the solidification layer, and finally the upper surface is solidified, the segregation components and The metal inclusions are separated on the upper surface of the slab to obtain a thick slab-shaped slab with less segregation and non-metal inclusions. An object of the present invention is to provide a continuous casting machine and a continuous casting method for producing a thick slab-shaped slab with less segregation and non-metallic inclusions.

[0005]

FIG. 1 is an overall explanatory view of a continuous casting machine of the present invention, (A) is a front explanatory view, and (B) is a plan explanatory view. The continuous casting machine of the present invention has a metal belt 1 whose rear surface is cooled and runs sideways. In the present invention, the term “sideways” means approximately horizontal with an inclination angle of 5 ° or less. The metal belt 1 is an endless metal belt that is a pulley 2a.
And 2b, and the pulleys 2a and 2b are rotated in the arrow direction. Reference numeral 5 in the figure is a cooling device for cooling the back surface of the metal belt 1.

A secondary cooling zone 3 is arranged at the end (outgoing side) of the metal belt 1 in the traveling direction. The secondary cooling zone has many rollers 4
And an injection nozzle 6 arranged between each roller 4. Each injection nozzle 6 injects a cooling medium, such as water, upward.
A large number of rollers 4 are arranged on the extension line of the metal belt so that the upper ends thereof are at the same height as the metal belt 1.

The continuous casting machine of the present invention is also provided with a space corresponding to the width W of the cast slab 7 to be manufactured, and the metal belts 1 and 2 are provided.
A pair of side wall weirs 8a extending over the next cooling zone 3
And 8b. The side wall weirs 8a and 8b run in the same arrow 9 direction as the metal belt 1 at the same speed as the metal belt 1.

Two or more side surface weir blocks, for example, 8-1 to 8-5 in FIG. 1 (B) are connected in a lengthwise direction so as to be separable to form side surface weirs. When the solidification of the molten metal is completed, for example, the side block 8-
5 is separated from the side wall 8a and transferred to the back of 8-1,
When the operation of connecting to the tail end portion of the side surface weir block 8-1 is sequentially performed, the side surface weir block 8-1 to 8-5 is connected to the side surface weir block 8-1.
a can be formed.

In the present invention, a molten metal supply tank 12 is provided which has a gutter 10 and a hot water storage portion 11, and the end portion of the gutter 10 is arranged between the side surface weirs 8a and 8b on the inlet side of the metal belt 1. The end portion of the gutter 10 is arranged in close contact with the metal belt 1 and the side surface dams 8a and 8b.

In the present invention, the molten metal 13 is poured into the molten metal storage portion 11 to form a molten metal reservoir in the molten metal supply tank 12 in the space defined by the side surface dams 8a, 8b and the metal belt 1. The molten metal 13 in the pool is cooled by the metal belt 1 to form a solidified shell 14 on the metal belt 1. The solidified shell 14 follows the running of the metal belt 1 and grows while running in the direction of arrow 9.

The solidified shell reaching the end of the metal belt 1 in the running direction is supported by the roller 4 thereafter. When changing from supporting by the metal belt 1 to supporting by the roller 4,
Although the unsolidified molten metal 13 remains on the solidified shell 14, the solidified shell 14 has grown and is already thick and has sufficient strength.
Even if the support is changed to, there is no breakage or other trouble.

Since the unsolidified molten metal 13 exists above the solidified shell 14, the side wall 8 is also formed in the secondary cooling zone 3.
The side surfaces are continuously supported by a and 8b, and the molten metal 13 is prevented from flowing out from the side surfaces.

In the secondary cooling zone 3 also, the solidification shell 14
The bottom surface is continuously cooled by a cooling medium such as water jetted from the jet nozzle 6, continues to grow while traveling in the arrow 9 direction, completes solidification, and becomes a thick slab slab 7. The slab 7 is cut into a desired length by a conventional means, for example, a cutting machine (not shown) provided on the outlet side of the secondary cooling zone 3.

[0014]

FUNCTION FIG. 2 is a schematic illustration of solidification of molten metal. The molten metal forms a solidified shell 14 on the bottom surface, and this solidified shell 14 grows upward. However, when the growth speed of the solidification shell 14 is slow, the temperature of the upper part of the molten metal drops, and the surface solidified layer 15 is formed on the upper surface of the molten metal. Surface solidification layer 15 and solidification shell 1
No. 4 is united to form a slab 7 which is completely solidified. At the time of this coalescence, a part of the molten metal 13 is sandwiched between the surface solidified layer 15 and the solidified shell and is confined in the slab.

The molten metal confined in this slab finally solidifies, but since the confined molten metal contains segregation components and non-metallic inclusions, segregation occurs in the slab 7. However, the cleanliness is impaired. In addition, porosity is generated in the last solidified portion.

In the inventions of Japanese Patent Publication No. 53-19290 and Japanese Patent Application Laid-Open No. 61-14067 described above, a flat mold whose bottom surface is formed by an ordinary surface plate is used. Has a slow solidification rate, and the temperature of the molten metal in the upper part drops quickly due to the flat mold, so that the surface solidified layer 15 is apt to occur, and the cast piece easily traps a part of the molten metal. Removal of metal inclusions is not sufficient.

In the present invention, the bottom of the slab 14 is the metal belt 1
And the injection nozzle 6 for water cooling, and since the injection nozzle 6 directly injects water to the bottom of the slab without passing through the metal belt 1, strong cooling is obtained.
Has a high growth rate and reaches the upper surface in a short time, so that the surface solidified layer 15 is unlikely to occur. Therefore, it is easy to obtain a slab with less segregation and non-metallic inclusions.

A continuous casting apparatus for forming a small molten metal pool by arranging the rear weir shown by 16 of FIG. 2 on the metal belt 1 without using the molten metal supply apparatus of the present invention shown by 12 of FIG. 1 is considered. To be However, according to the knowledge of the present inventors, in the case of the small pool shown in FIG. 2, since the heat capacity of the pool is small, the surface solidification layer 15 is generated and segregation, non-metallic inclusions, or porosity is prevented. May be insufficient.

In the present invention, as shown in FIG. 1, a molten metal reservoir in the molten metal supply tank 12 is formed. Therefore, the heat capacity of the molten metal is large and the generation of the surface solidification layer 15 is further prevented. For this reason, a cast slab 7 from which segregation and non-metallic inclusions have been removed more sufficiently can be obtained.

The continuous casting machine of the present invention may be provided with a stirring device 17 for stirring the molten metal in the pool and a heating device (not shown) for heating the molten metal in the hot water storage portion 11. As the stirring device, for example, an electromagnetic stirring device utilizing electromagnetic induction can be used. As the heating device, for example, a general-purpose induction heating device in which an induction coil is arranged on the outer periphery of the hot water storage unit 11,
A normal electric arc heating device or the like for heating the molten metal from above can be used.

It is preferable to stir or heat the molten metal in the basin by using the stirring device 17 or the heating device because the formation of the surface solidification layer 15 is further prevented.

In the continuous casting operation of the present invention, a heat retaining agent can be placed on the surface of the molten metal. As the heat retaining agent, for example, various exothermic heat retaining agents or heat insulating heat retaining agents used for retaining the temperature of the feeder portion of the steel ingot can be used. The use of this heat-retaining agent further prevents the temperature drop in the upper part of the molten metal in the basin, so that the formation of the surface solidification layer 15 can be further prevented, which is more preferable. In the present invention, the stirring device 17, the heating device and the heat retaining agent are selected and used or used in combination as necessary.

[0023]

By implementing the present invention, coagulation can be
It is possible to grow a slab with a thick slab that grows exclusively from the bottom surface to the top and finally solidifies the top surface, and segregation of the slab and non-metallic inclusions can be greatly reduced.

[Brief description of drawings]

FIG. 1 is an overall explanatory view of a continuous casting machine of the present invention, and FIG. 2 is a schematic explanatory view of solidification of molten metal.

[Explanation of symbols]

1: metal belt, 2a (2b): pulley, 3: secondary cooling zone, 4: roller, 5: cooling device, 6: injection nozzle, 7: cast slab, 8a (8b): side wall, 9: metal belt , Solidification shell, running direction of side dam, 10: gutter,
11: Hot water storage part, 12: Molten metal supply tank, 13: Molten metal,
14: solidified shell, 15: surface solidified layer, 16: rear weir, 17: stirrer.

Claims (4)

[Claims] 1. A metal belt having a back surface cooled and running horizontally, a large number of rollers each having an upper end arranged at the same height as the metal belt, and an injection nozzle for injecting a cooling medium upward between the rollers. Then, the secondary cooling zone connected to the outlet side of the metal belt and the metal belt and the secondary cooling zone extend at intervals corresponding to the plate width of the slab to be produced and run in synchronization with the metal belt. Characterized by having a pair of side weirs, and a molten metal supply tank in which a gutter and a hot water storage part are provided, and the end of the gutter is arranged in close contact with the metal belt and the side weir between the side weirs on the inlet side of the metal belt. Slab continuous casting machine. 2. A continuous casting machine for slabs, wherein the continuous casting apparatus according to claim 1 comprises a stirring device for stirring the molten metal in the pool and a heating device for heating the molten metal in the hot water storage section. 3. The continuous casting machine according to claim 1 is used to inject molten metal into a molten metal storage part to form a pool on the metal belt, which is in communication with the molten metal in the molten metal supply tank. A continuous casting method of a slab, characterized in that a solidified shell is generated in the step (3), the solidified shell is allowed to grow while running following the running of a metal belt, and solidification is completed in a secondary cooling zone to form a thick slab. 4. The continuous casting method according to claim 3, wherein a heat retaining agent is provided on the surface of the molten metal.