JPS6035223B2 - Molten steel solidification method for continuous casting equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for solidifying molten steel in continuous casting equipment, and more particularly, to a method for solidifying molten steel in continuous casting equipment, which prevents breakout from occurring when stripping coins from the casting ring in the early stage of casting. Regarding the method.

Generally, in continuous casting equipment, during casting, a dummy bar is inserted into the mold in advance, and the insertion end of the dummy bar is connected to the coin coin that is formed by solidifying the molten steel supplied to the mold.
A dummy bar is used to pull out the tip of the slab to a position where steady operation is possible.

To connect the dummy bar and the coin piece, a connecting metal fitting attached to the tip of the dummy bar is used, but in order to solidify the molten steel early at the start of casting, a large amount of cold material is poured into the mold in advance. Prevents the connecting fittings at the tip of the dummy bar from melting, and
The rust piece is made to have sufficient strength to transmit the coin pulling force. Figure 1 shows a conventional method of charging cold material. As shown in this figure, a mushroom-shaped connecting fitting 3 is arranged at the top of the tip of the dummy bar 2 that has been inserted into the mold 1 in advance, and in order to rapidly cool the molten steel 5 that flows down from the nozzle 4 above the mold 1. A plurality of cold strips 7 made of strips such as round bamboo are provided together with iron chips 6 to help the solidified shell grow. The cold village 7 is simply put into the mold 1, and when it is put, it is randomly arranged leaning against the wall of the mold 1. However, when the molten steel 5 is rapidly cooled by the cold material 7 arranged as in the past, the formation of the solidified layer becomes unstable and the thickness of the solidified layer is not uniform when the dummy bar 2 and the mirror piece are pulled out. However, there is a drawback that cracks are likely to occur in the thin part of the solidified layer.

Therefore, when casting with a rotary caster, as shown in FIG. 2, when the mirror piece 10 is peeled off from the casting plate 8 with a peeling knife 9 downstream of the mold, bending tension is applied to the solidified layer 11 on the side of the contact surface with the casting plate 8. As a result, cracks occur in the thin solidified shell portion 12, and a so-called breakout occurs in which internal terminal solidified molten metal flows out from the cracks, resulting in a fatal defect that makes casting impossible. Such a breakout phenomenon frequently occurs in the initial stage from the position where the tip of the coin 10 is separated from the casting rod 8 to the point at which correction to the straight line is completed. As a result, in the conventional method of solidifying molten steel by arranging the cold material 7, if the casting theory 8 is made small, the distortion of the solidified layer 11 due to bending becomes large and breakout is promoted, so
There are problems in that it is not possible to make a mold, and furthermore, the casting speed cannot be increased, making it impossible to improve production efficiency. The purpose of the present invention is to uniformly and stably increase the growth of the solidified layer at the tip of the slab which is the joint part with the dummy bar, especially the solidified layer on the side of the contact surface with the casting wheel. It is an object of the present invention to provide a method for solidifying molten steel in continuous casting equipment, which can prevent the occurrence of cracks due to bending and thereby prevent the occurrence of breakouts. In order to achieve the above object, the method for solidifying steel in a continuous casting facility according to the present invention provides a method for solidifying steel in a continuous casting facility having a casting ring, in which a dummy bar is formed at the top of a dummy bar tip along the flow direction of the coin coin. A plurality of strips serving as cold material having at least a straightening length are provided, and these strips are curved into an arc shape of the same D as the casting wheel, and the plurality of strips are connected to the casting ring circumferential surface. By maintaining a predetermined distance and arranging the mirror piece along the circumferential surface, the mirror piece is solidified and formed while increasing the solidification layer on the casting contact surface side of the molten steel supplied to the mold. We aimed to increase the strength against bending.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method for solidifying port steel in continuous casting equipment according to the present invention will be described in detail below with reference to the drawings.

FIG. 3 shows the continuous casting equipment used in this example.

This continuous casting equipment has a disc-shaped casting wheel 8 and a casting mechanism 8.
The mold 1 is provided with a belt 13 that partially covers the outer periphery of the mold 1. That is, a groove 14 is formed on the outer peripheral surface of the cast ring 8 over the entire circumference, and the belt 13 is brought into contact with the end of the flange 5 of the groove 14 so as to cover about a quarter circumference of the groove 14. A mold 1 is formed. The casting wheel 8 is driven counterclockwise in the figure, and the belt 13 is also driven by the casting wheel 8.
It is possible to move while maintaining the supported state in synchronization with. A cast slab 10 is downstream of such a mold 1.
is peeled off from the casting mold 8 and becomes curved, forming the mold 1.
A peeling knife 9 for straightening the coin pieces 10 discharged from the bank into a rod shape and supplying the coins to the conveyance line has its sharp end facing upstream,
It is installed inside the groove 14. In such continuous casting equipment, a dummy bar 2 is used to assist in pulling out the rust pieces 10 to the point where the correction is completed in the initial stage of casting and to enable steady operation of the equipment.

The dummy bar 2 has substantially the same cross-sectional shape as the coin, and is constructed by mutually supporting and connecting a large number of bars. Also,
A mushroom-shaped connecting fitting 3 is protruded from the top of the dummy bar 2, so that when the molten steel 5 supplied from the nozzle 4 installed above the mold 1 solidifies, the mirror piece 10 and the dummy bar 2 are fully connected. are connected to each other so that the pulling force can be transmitted. In such equipment, a cold material 16 is placed in advance above the tip of the dummy bar 2 that is inserted into the mold 1 at the start of casting.

This cold material 16 has a plurality of strips 17 arranged in the flow direction of the rust pieces 10 and the strips 17 arranged in parallel at a predetermined pitch, and the arranged strips 17 are cast in a casting mold 1. The holding cold village 18 is held and welded to the strip 17 along the circumferential surface of the holding cold village 18. The strip 17 has a cross-sectional area that is not completely dissolved by the molten steel 5 until the rust pieces 10 are peeled off from the casting ring 8, and has a diameter d = 3 to 3.
A round bar with a ratio of 1 is used. Further, the strip 17 is curved into an arc concentric with the center of curvature of the casting wheel 8, and the arrangement pitch is 12.
12=2. The circumferential surface of the casting ring 8 and 1. =1. World~3. Dummy bar 2 with a separation distance of M
It is welded to the top side of the gate-shaped cold holding material 18 so as to be disposed above the tip. The holding cold villages 18 are arranged in the cross-sectional direction of the mold 1, and are provided at two locations in the longitudinal direction of the strip 17 in a direction perpendicular to the strips 17. The total length of the strip 17 connected to this holding cold material 18 is approximately twice the distance from the exit of the mold 1 to the peeling knife 9, and the drawn coins 10 can be continuously cast in a steady state, and peeling correction can be performed. The length to reach the completed position, that is, the corrected length me, is adjusted to 1 = 0.3 to 1.0R or more, where R is the casting diameter. A method of solidifying and casting molten steel 5 using the equipment configured as described above is carried out as follows.

That is, in preparation for starting casting, the dummy bar 2 is inserted into the mold 1 in advance. In this mold 1, a cold village 16 is formed on the top of the tip of the dummy bar 2. This cold village 16 is a strip material 1
7 is positioned so as to correspond to the circumferential surface of the cast ring 8, and the cold holding material 18 is used to keep the distance 1 between the strip 17 and the circumferential surface of the cast ring 8 constant. It is something to be retained. Next, the molten steel 5 is poured into the mold 1 from the nozzle 4.
The dummy bar 2 is pulled out by driving the casting rod 8 and the belt 13 while injecting the dummy bar 2 into the inside. The molten steel 5 is a casting wheel 8
, a solidified layer is formed on the contact surface of the belt 13, and the cold material 1
The solidified shell grows and increases around 6, and in particular, the solidified layer 11 on the side of the contact surface with the surrounding surface of the casting mechanism 8 grows larger than other solidified layers and becomes a thick layer. This solidified layer 11 has a stable and uniform thickness T over the installation range of the cold material 16 because the strips 17 of the cold material 16 are not disturbed by the injection of the molten steel 5 and are aligned at a distance of 1. It solidifies and grows as shown in Fig. 4. After that, the tip of the coin 10 that has come out of the mold 1 is attached to a peeling knife 9 along with a dummy bar 2.
The part is peeled off from the casting rod 8 by the knife 9 and straightened from a curved state to a straight state. At this time, bending tension is applied to the solidified layer 11 on the contact surface side of the casting wheel 8 in the flow direction due to the peeling action of the knife 9, but the solidified layer 11 becomes a uniform thick layer due to the arrangement of the cold material 16. No cracks occur even with this acting force. Since such a coagulated layer 11 extends over a distance corresponding to the straightening length,
The coin piece 10 continues to be drawn out in a steady state, and breakout is prevented from occurring during such initial casting. As a result, in particular, the thickness of the solidified layer on which the bending tension acts is reliably and stably formed, making it possible to increase the bending tension resistance. Even if the casting speed becomes faster, it can be sufficiently coped with, and stable operation can be achieved by downsizing the casting wheel 8 and high-speed casting. In the above embodiment, the cold material 16 is composed of the round strip material 17 and the holding cold material 18, but the same effect can be obtained even if square material is used.

As described above, according to the present invention, the solidified layer on the casting contact surface side can be made into a stable and uniform thick layer using cold material at the early stage of casting, and cracks will not occur even when peeled off with a knife. Breakout occurrence can be minimized.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the placement of the cold material used in the secondary tank, Fig. 2 is a cross-sectional view showing the state of the solidified shell shape of the coin by the rotary caster, and Fig. 3 is the arrangement of the cold material used in this example. figure,
FIG. 4 is a sectional view of the mold during the same casting. 1... Mold, 2... Dummy Herr, 3...
・Connection fittings, 5... Molten steel, 7, 16...
- Reimura, 8... Casting ring, 9... Peeling knife, 10... Money piece, 11... Solidified layer. Figure 4 Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. A plurality of strips serving as cold material having at least a straightening length along the flow direction of the slab are attached to the top of the tip of a dummy bar for drawing the slab, which is inserted into the mold in advance in the initial stage of casting by continuous casting equipment equipped with a casting wheel. At the same time, these strips are curved into an arc concentric with the cast ring, and the plurality of strips are arranged at a predetermined distance from and along the circumferential surface of the cast ring. A method for solidifying molten steel in continuous casting equipment, characterized in that the slab is solidified and formed while increasing the thickness of the solidified layer on the casting wheel contact surface side of the tip of the slab connected to the dummy bar compared to other parts.