JPH03216246A - Method for sequentially continuous-casting different steel kinds - Google Patents

Abstract

PURPOSE:To make the length of cast slab composed of the mixed composition of premolten steel and post molten steel as shorter as possible and to prevent slag inclusion of powder slag by standing a guide rod facing to a pouring hole for molten steel in a tundish and arranging plate-like refractory, which can float on the molten steel, so that the guide rod is loosely inserted into center hole thereof. CONSTITUTION:After completing pouring of the previous molten steel 4 into the tundish 1, at the time of continuing the pouring of the previous molten steel 4 into a mold 8, the refractory ring 7 is descended while guiding through the tundish stopper 2. At the same time, when the previous molten steel runs out, lower face of the ring 7 and bottom face of the tundish 1 contact under condition of damming up the powder slag 6 with outer peripheral face of the ring 7 to prevent flowing of the powder slag 6 into the pouring hole 10 for molten steel. Successively, at the same time of charging a sequence block 9 into the previous molten steel 4 in the mold 8, the following molten steel 5 is poured into the tundish 1. At the time, when the following molten steel 5 pours in the prescribed quantity, the stopper 2 is risen and the following molten steel 5 is poured into the mold 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for continuous continuous casting of different steel types, which involves continuous casting of different mesh types by continuous casting.

[Conventional technology]

In recent years, in continuous casting, it has become possible to use tundishes economically and improve the operating efficiency of continuous casting equipment. The so-called continuous continuous casting of different types (hereinafter referred to as continuous casting of different types) is carried out.

Regarding the specific method of continuous casting of different steel types, we will explain the case in which Klk control of pouring from the tundish into the mold is performed using a tundish stopper. First, we will explain the process for continuous casting of different steel types as shown in Fig. 4. As shown in the figure, after the pre-molten steel is poured from the ladle (not shown) into the tundish l3 {4th U; jI(a)}, the pre-molten steel 14 in the tundish l3 is poured into the mold 15. Continuously pour as much molten steel as possible (Fig. 4 et al.) from the ladle (not shown) into the post-molten steel 16 to match the reduced amount of the pre-molten steel l4, and mix the pre-molten steel 14 and the post-molten steel 16. Continuously pour the molten metal into the mold 15 without interrupting it between the joints {Figure 4 (C)
} method is known. Alternatively, as a second method, as illustrated in Section 5v4, a ladle (not shown) may be used.
After pouring the premolten steel from the tundish l3 into the tundish l3 {Figure 5 (a} l, the premolten steel 814 in the tundish l3 is poured into the mold 1
After continuing to pour the molten steel into the mold 15 to reduce the amount as much as possible, the pouring port 17 of the tundish 13 is closed with the tundish stopper 18 (Fig. 5(b)).
In parallel with charging sequence block I9 to 4,
Pour the post-melt tFtll6 from the ladle (not shown) to match the reduced pre-melt 814 in the tundish l3.
FIG. 5(c)}, Post-melting 216 into the tundish 13
When a predetermined amount of molten metal is poured, the tundish stopper 18
Raise the temperature and pour into the mold 15 again {Figure 5(d)}
method is known.

Alternatively, if the flow rate of pouring from the tundish to the mold is controlled by a slide valve provided under the bottom of the tundish, a simple stopper may be provided on the tundish and the fifth
It is also known to perform the procedure shown in the figure. In addition, in the figure, 20 indicates an immersion nozzle, and 21 indicates a powder slag.

(Problems to be Solved by the Invention) By the way, in the case of continuous casting of the first different steel types described above, the length of the slab becomes longer due to the mixed components of the pre-molten steel 14 and the post-molten steel 16, and especially when the pre-molten steel 14 and after 't8 fiA
When the difference in composition from HA 16 is large, it takes time for the molten steel in the tundish 13 to become the post-molten steel composition, and the length of the slab due to the mixed ingredients becomes even longer, so the post-molten steel HA 16
The loss becomes large. Furthermore, in the case of the second continuous casting of different steel types and the use of a slide valve, the front part of the tundish 13 is lower than the first continuous casting of different steel types. Although it has the advantage of reducing the remaining amount of g w414 and shortening the length of the slab due to the mixed components, it is possible to reduce the setup work from the end of pouring the pre-molten steel 14 to the start of pouring the post-molten steel 16. If this is not done within a short period of time while the pre-molten fa14 remaining in the dish l3 is in the pourable temperature range, metal rolling will occur on the head of the tundish stopper 18 that blocks the pouring port 17. , after-dissolution [
16, it becomes impossible to control the flow rate of molten steel at the start of pouring, making stable continuous casting of different steel types impossible.

On the other hand, as mentioned above, the reason why the pre-molten steel 14 remains even though slabs consisting of mixed components are generated and the yield is poor is that when the pre-molten steel 14 is completely cast, the amount of remaining molten metal of the pre-molten steel 14 is This is because as the amount decreases, a vortex is generated above the pouring hole 17 of the tandy sosh 13, and this vortex causes the powder slag 21 covering the surface of the molten steel to be drawn in together with the pre-molten steel 8I4, thereby degrading the quality of the slab. The present invention has been made in view of the above-mentioned problems, and its purpose is to reduce the scraping force on the length of the slab made of mixed components, and to enable stable continuous casting of different steel types. This provides a continuous casting method for different steel types. [Means for Solving the Problems] In order to achieve the above object, the continuous casting method of different steel types according to the present invention includes heating the post-molten steel after the pre-molten steel in the tundish is completely poured into the mold. When continuously pouring different steel types into a mold, a guide rod is installed facing the molten steel pouring hole in the tundish, and
A center hole of a plate-shaped refractory that can float on the molten steel and whose outer diameter is three times or more the inner diameter of the molten steel pouring port is loosely inserted into this guide rod. This system dams up the powder slag that covers the molten steel surface from flowing into the nozzle, and, following the pre-molten steel, receives the post-molten steel from the molten steel container into the tundish and pours it into the mold. And facing the bottom surface of the plate refractory? The bottom surface of the tundish near the 8-hole pouring spout may be raised.

[For production]

In the continuous casting method of different steel types according to the present invention, a guide rod is set upright facing the molten steel pouring port in the tundish, and a center hole of a plate-shaped refractory that can float on the molten steel is loosely inserted into the guide rod. Since the powder slag covering the molten steel surface is dammed up by the outer circumferential surface of the plate-shaped refractory, and its outer diameter is 376 or more than the inner diameter of the molten steel pouring port, the amount of remaining molten steel can be reduced. It is possible to prevent the powder slag from being dragged into the tundish due to the swirling current that occurs as the amount decreases. Furthermore, since it is a plate-shaped refractory, pre-molten steel can be poured almost completely until the bottom surface of the refractory comes into contact with the bottom surface of the tundish, without powder slag being involved. In this way, after the pre-trill is almost completely drained, the post-molten steel is received from the molten steel container into the tundish and poured into the mold, so the length of the mixed component slab with the post-molten steel can be shortened, and the post-molten steel can be shortened. Yield can be improved.

Furthermore, as mentioned above, since the pre-molten steel can be poured almost completely, when a tundish stopper is used as the guide rod, there is no occurrence of metal wrapping due to the pre-molten steel on the head of the tundish stopper. In addition, the above-mentioned plate-shaped refractory is made to be heavier than powder slag and adjusted to have a weight that floats on the surface of the molten steel, and the lower surface of the plate-shaped refractory... The powder slag flowing between the 8E surfaces is dammed by its outer peripheral surface. Furthermore, by making the area near the molten steel pouring port in the tundish higher than the bottom of the tundish, the lower surface of the plate-shaped refractory and the upper surface of the bulky part can be reliably brought into contact with each other, and powder slag can be more reliably poured into the tundish. Blowing into the mold can be prevented.

Further, the shape of the plate-shaped refractory may be rectangular in addition to circular. In the case of this rectangular shape, the size should be such that the shortest length between the outer edges passing through the center of the guide rod insertion hole is at least three times the inner diameter of the molten steel pouring port in the tundish. [Example] Hereinafter, an example according to the present invention will be described based on the drawings.

FIG. 1 is a schematic cross-sectional view between a tandy sosh and a mold for explaining the procedure of the continuous casting method of different steel types according to the present invention.

In the figure, l is the tundish, 2 is the tundish stopper, 3 is the immersion nozzle provided at the bottom of the tundish 1,
4 is a pre-molten steel, 5 is a post-molten steel, 6 is a powder slag, 7 is a refractory ring immersed in the powder slag 6 and floating on the molten steel, and loosely inserted into the tundish stopper 2, 8 is a mold, and 9 is a The sequence block is shown, and the tundish 1 is configured so that its weight can be measured using a scale (not shown). Using the tundish 1 having the above-described configuration, the method of successively casting different steel types according to the present invention is carried out as follows. First, after finishing pouring the pre-molten steel 114 from a ladle (not shown) into the tundish 1, pouring the pre-molten steel 4 from the tundish l into the mold 8 is continued. {See Figure 1 (a)} After this, the weight of the tundish 1 is reduced to a predetermined weight (pre-molten steel 4
The weight of tundish 1 when it is almost gone! ) Continue pouring into the mold 8. As a result, the refractory ring 7 descends guided by the tundish stopper 2 and the pre-molten steel 4 disappears, while at the same time the powder slag 6 is dammed up on the outer circumferential surface of the refractory ring 7 and the lower surface of the refractory ring 7 The bottom surface of the tundish L comes into contact with the bottom surface of the tundish l to prevent the powder slag 6 from flowing into the molten steel pouring hole 10. Thereafter, the tundish stopper 2 is lowered to close the molten steel pouring port 10. {See Figure 1)} Next, mold 8
At the same time as loading the sequence block 9 into the front 11gi 14 of the tundish 1, place the post-melting ladle [5] into the tundish 1.
(not shown). As the post-molten steel 5 rises due to this pouring, the refractory ring 7 also rises while being guided by the tundish stopper 2 while blocking the powder slag 6 on its outer peripheral surface. When a predetermined amount of molten steel 5 is poured into the tundish 1, the tundish stopper 2 is raised and pouring of the molten steel 5 into the mold 8 is started. {1st
See Figure (C)} In this way, the powder slag 6 is dammed up on the outer peripheral surface of the refractory ring 7, and while the powder slag 6 remains inside the tundish 1, almost the entire amount of the pre-molten steel 4 in the tundish 1 is removed. The molten steel can be poured into the mold 8, and after this, the molten steel pouring port 10 is closed by the tundish stopper 2, and the molten steel 5 is poured from the ladle into the tundish I. Pre-molten TGI on the head of
It is possible to successively cast different types of steel without producing bullion rolling due to l4, and the length of the mixed component slab with the post-molten steel 5 can be shortened, and the yield of the post-molten steel 5 can be improved. In the above embodiment, a tundish stopper is used as a guide rod, and after pouring almost the entire amount of pre-molten steel in the tundish into the mold, the molten steel pouring port is closed with this tundish stopper, Although an example in which molten steel is received has been described, a refractory guide rod may be used in place of the tundish stopper, and the molten steel pouring port may be closed with a slide valve.

What is shown in FIG. 2 is a schematic cross-sectional view between a tundish and a mold for explaining the procedure of another embodiment of the continuous casting method of different steel types according to the present invention, and shows the immersion nozzle having the configuration shown in FIG. 1 above. The molten steel pouring spout 10 in the tundish 1 in which the tundish 1 is provided is constructed by providing a refractory material I2 for raising the height, which protrudes from the inner bottom 11 of the tundish 1 by a predetermined height and has a flat top surface. be. Using the tundish l having such a configuration, the continuous casting method for different steel types according to the present invention can be carried out in the same procedure as described in the example of FIG. 1. By providing such a refractory for elevating 12, when pouring into the mold 8 continues and the pre-molten steel 4 falls below the upper surface of the refractory for elevating 12, the lower surface of the refractory ring 7 becomes refractory for elevating. Make sure to contact the top surface of object 12 {
Refer to FIG. 2 (C)}, as described above using FIG.
It is possible to successively cast different types of steel without causing metal rolling due to the pre-molten steel IIA4 on the head of the steel, and the length of the mixed component slab with the post-molten steel 1115 can be shortened, and the yield of the post-molten steel 5 can be improved. In addition, in the above embodiment, the molten steel pouring port 1 in the tundish 1
0 is close to the side wall of the tundish 1 and the inner bottom 11 of the two-tiered bottom is relatively large. However, the present invention is not limited to this, and as shown in FIG. , the upper base 11a surrounds the molten steel pouring port 10 in the tundish 1.
It is formed into a relatively small two-tiered bottom consisting of a bottom bottom of 1lb,
It is also possible to perform continuous casting of different steel types using the refractory ring 7 larger than the upper base 11a, and in this case also, the same effects as described in the above embodiment can be obtained. [Effects of the Invention] As described above, according to the continuous casting method of different steel types according to the present invention, the length of the slab made of mixed components can be made as small as possible, the outflow of powder slag into the mold can be suppressed, and stable casting can be achieved. Capable of continuous casting operations of different steel types.

[Brief explanation of drawings]

1 and 2 are schematic cross-sectional diagrams between a tundish and a mold to explain the procedure of the continuous casting method of different steel types according to the present invention, and FIG. Figures 4 and 5 are schematic cross-sectional diagrams between a tundish and a mold for explaining the procedure of a conventional continuous casting method of different steel types. . Tundish Tundish stop collar immersion nozzle 4 Pre-molten steel and post-molten steel 6 Powder slag refractory ring 8 Mold sequence block molten steel pouring port Refractory for raising the inner bottom of the tundish

Claims (2)

[Claims] (1) After the pre-molten steel in the tundish has been poured into the mold, the post-molten steel is received and poured into the mold. During continuous casting of different steel types, the guide rod is placed opposite the molten steel pouring port in the tundish. is erected, and a center hole of a plate-shaped refractory whose outer diameter is three times or more the inner diameter of the molten steel pouring port and which can float on the molten steel is loosely inserted into this guide rod. The outer peripheral surface of the refractory blocks the flow of powder slag that covers the molten steel surface into the nozzle, and following the pre-molten steel, the post-molten steel is received from the molten steel container into the tundish and poured into the mold. Continuous continuous casting method for different steel types. (2) The method for continuous continuous casting of different steel types according to claim 1, characterized in that the bottom surface of the tundish near the molten steel pouring port facing the bottom surface of the plate-shaped refractory has a raised shape.