JP2589308B2 - Casting start method in continuous casting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention uses a continuous casting machine (for example, a twin caster) for supplying molten metal from a plurality of nozzles to one or a plurality of molds for a slab drawing control system. The present invention relates to a new casting start method when casting by casting.

<Prior Art> An example of a continuous casting machine is shown in the perspective views of FIGS.

Nozzle (13) for supplying molten metal (6) in mold (12) from tundish (11) in continuous casting machine
(Hereinafter simply referred to as a nozzle) and a control system for extracting the slab (7) (hereinafter referred to as an extraction device (14)) are usually
There is a one-to-one relationship, and control for keeping the liquid level in the mold (12) constant is achieved by changing the flow rate of the molten metal from the nozzle (13) or the drawing speed of the drawing device (14). .

However, in recent years, a pair of extraction devices (14)
On the other hand, a method in which molten metal is supplied from a plurality of nozzles (13) to one or a plurality of molds (12) to perform continuous casting is being adopted. Typical examples are a twin caster shown in the perspective view of FIG. 4 and a beam blank continuous caster having a complicated slab cross-sectional shape seen in the perspective view of FIG.

By the way, the method for starting casting in the continuous caster as described above requires the following conditions.

In the twin caster, at the time of starting the drawing of the slab, it is necessary that all the liquid surfaces in the plurality of molds (12) are at the same position within an allowable range. Therefore,
The supply timing of the molten metal (6) from the nozzle (13) into the mold (12) must of course be the same. In the case of continuous casting using a submerged nozzle in the beam blank continuous caster, a plurality of nozzles are required before the discharge hole of the nozzle (13) is hidden under the molten liquid level in the mold (12). It is necessary to check the supply state of the molten metal from (13). This is because it is not possible to confirm whether or not the state of supply of the molten metal from the nozzle is appropriate when the liquid level is below the liquid level.

Means for satisfying such a condition include:
As shown in the longitudinal sectional views of FIG. 7 and FIG.
It is effective to use a stopper (10) as in JP-A-56-165552, and a stopper (10) is provided for each of a plurality of nozzles (13) mounted on a tundish (11), and By means of them all stoppers (10)
Are simultaneously adopted to realize the simultaneous supply of the molten metal (FIG. 6). Simultaneous supply of molten metal (6) from a plurality of nozzles (13) is realized by a single manual operation using a device that physically links a plurality of stoppers (10) (Fig. 7). doing.

<Problems to be Solved by the Invention> However, the above-described conventional technologies have the following difficulties. That is, in the stopper method, the cost of the stopper is increased and the price of the continuous casting machine itself is increased.

In the case of the interlocking stopper system, a complicated mechanism for simultaneously interlocking a plurality of stoppers is required, and the structure of the continuous casting machine is complicated.

The stopper system that does not interlock requires an operator, and is a hindrance to labor saving.

I am worried about the reliability of the stopper itself.

<Means for Solving the Problems> The present invention provides a one-to-one casting method in which a nozzle and a drawing device are used, that is, a cylindrical refractory pipe or an iron pipe is set up on a nozzle tuyere (nozzle upper end opening), The molten metal is removed and overflows (JP-A-53-37137, JP-A-54-37137).
No. 124828), or a method of utilizing buoyancy in a general method of starting casting by melting a cylinder by the latent heat of a molten metal.

That is, the method of starting casting in continuous casting according to the present invention includes a method of starting molten metal (6) provided at a position corresponding to a plurality of nozzles (13) attached to a tundish (11). (2) and these cylindrical parts (2)
It has a hollow connecting portion (3) for generating buoyancy while connecting and fixing the space, and has an apparent bulk specific gravity as a whole structure smaller than the specific gravity of the molten metal (6) as a physical property. An integrated pipe (1) made of a material that does not melt or break in the time (usually within 5 to 10 minutes) from the start of injection of molten metal to the start of casting, (13) After the tuyere is set in advance so that the tuyere and the cylindrical portion (2) coincide with each other and a necessary joining force is obtained, the molten metal (6) is poured into the tundish (11). The joining force between the tuyere of the nozzle (13) and the cylindrical portion (2) is released based on the buoyancy of the specific gravity difference between the integrated pipe (1) and the molten metal generated in the integrated pipe (1) by the injected molten metal. Of the molten metal (6) in the mold (12) from a plurality of nozzles (13). Characterized in that it starts at the same time.

The apparent bulk specific gravity of the structure as a whole, which is smaller than the specific gravity of the molten metal as a physical property in the present invention, in other words, if the part of the integrated pipe (1) that generates buoyancy is hollow, even if the integrated pipe (1) is hollow, There is no problem even if the specific gravity of the material of the pipe (1) is larger than the specific gravity of the molten metal.

<Operation> According to the above method, if the buoyancy acting on the integral pipe (1) exceeds the joining force between the integral pipe (1) and the nozzle (13) tuyere, the integral pipe (1) ) Floats in the molten metal, and the molten metal is supplied into the mold (12) via the nozzle (13). At this time, since the rigidity of the integral pipe (1) having the plurality of cylindrical portions (2) is large, the joining force between the plurality of cylindrical portions (2) and the same number of nozzles (13) tuyeres is small. At the same time, the nozzle (13) tuyere opens at the same time,
The supply of the molten metal to the nozzle (13) is performed simultaneously. As a result, simultaneous supply of molten metal from a plurality of nozzles (13) to individual molds (12) can be realized. In addition, a hollow portion (4) is formed in the connecting portion (3) that acts to impart buoyancy to the integrated pipe (1).
Is provided, there is an advantage that the buoyancy of the integrated pipe (1) is further increased and the manufacturing cost of the integrated pipe (1) can be reduced.

<Examples> Examples of the present invention will be specifically described below.

FIG. 1 is a plan view showing an example of an integrated pipe used in the method of the present invention, FIG. 2 is a central vertical sectional view showing the same, and FIG.

As shown in these figures, the one-piece pipe (1) used in one embodiment of the method of the present invention comprises two nozzles (13) attached to a tundish (11). Molten metal (6) provided at a position corresponding to nozzles (13) and (13)
Two cylindrical parts (2) and (2) for preventing inflow, and an integral pipe (1) connecting between these cylindrical parts (2) and (2)
And a connecting portion (3) located on the upper end side of the cylindrical portion (2) that generates buoyancy as a whole. And, in order to further increase the buoyancy, the connecting portion (3) is provided with a hollow portion (4).

The above integrated pipe (1) has a nozzle (13) spacing of 1000mm
Was used for twin casters. This integrated pipe (1)
Is an integrally molded product made from a mixture of silica sand or a refractory and paper pulp, and the bulk specific gravity of the raw material mixture itself is 2.5.
The distance between the cylindrical portions (2) and (2) is 1000 mm, the size of the cylindrical portion (2) is 160 mm in inner diameter, 10 mm in thickness, and 300 mm in height. It was small. As shown in FIG. 3, the cylindrical portions (2) and (2) of the integrated pipe (1) are fitted to the tuyeres of the nozzles (13) and (13) attached to the dandysh (11), respectively. The joining was performed at the joining portion (A) using mortar.

After setting the integrated pipe (1) in the tundish (11) in this way, the molten metal (6) was poured into the tundish (11). 200-250 about 6 minutes after the start of injection
When the depth of mm was reached, the supply of the molten metal (6) into the mold (12) was started simultaneously from both nozzles (13) (13).

In addition, an experiment was conducted in which the integrated pipe (1) shown in FIGS. 1 and 2 used in the above example was applied to a slab twin caster for producing steel shown in FIG. 4 and a beam blank continuous caster shown in FIG. However, the uniformity of the slab (7) coming out of the mold (12) was good and a success rate of 100% could be obtained.
And, of course, the cost of casting has fallen.

In FIGS. 4 and 5, the pulling-out device (14) is shown only with rollers.

The method of the present invention can be applied to a continuous caster having any nozzle interval, and as described above, can be applied to a beam blank continuous caster. It is also possible to freely change the casting start time, that is, to advance or delay the casting, and it is also possible to move the connecting portion (3) closer to or away from the nozzle (13) tuyere, and it is possible to change its volume. And the size of the hollow portion (4) can be changed.

<Effect of the Invention> As described above, the use of the casting start method in the continuous casting according to the present invention makes it possible to significantly reduce the casting cost as compared with the conventional stopper method. In addition, the casting start operation in the twin caster is stabilized, and the trouble caused by the shift of the molten metal supply start to the mold can be completely eliminated.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of an integrated pipe used in the present invention, FIG. 2 is a central longitudinal sectional view of the same, and FIG. 3 is a central longitudinal sectional view showing a use state of the integrated pipe. is there. FIG. 4 is a perspective view of a main part illustrating a state of continuous casting by a twin caster, and FIG. 5 is a perspective view of a main part illustrating a state of continuous casting by a continuous beam blank caster. FIGS. 6 and 7 are central vertical sectional views showing a main part of a conventional example in which continuous casting is started by a stopper method. (1) Integral pipe, (2) cylindrical part (3) connecting part, (4) hollow part (6) molten metal, (11) tundish (12) mold, (13) nozzle

Claims (1)

(57) [Claims] A plurality of cylindrical portions (2) for preventing inflow of molten metal (6) provided at positions corresponding to a plurality of nozzles (13) attached to a tundish (11), and the cylindrical portions (2). ) Are connected and fixed, and the integral pipe (1) having a hollow connection part (3) for generating buoyancy is provided so that a plurality of nozzles (13) tuyeres and a cylindrical part (2) match. After the molten metal (6) is set in advance so as to obtain the necessary joining force, the molten metal (6) is poured into the tundish (11), and the nozzle is formed on the basis of the buoyancy generated in the integrated pipe (1) by the poured molten metal. (13) Continuous casting characterized by releasing the joining force between the tuyere and the cylindrical portion (2) and simultaneously starting the supply of the molten metal (6) into the mold (12) from the plurality of nozzles (13). Method for starting casting.