JPS58188543A - Continuous casting device of steel plate - Google Patents

Abstract

PURPOSE:To obtain a cast plate having good surface characteristics by supplying gas through the openings formed to a gate for preventing the leakage of molten steel and making the solidified layer at the inside bottom end of the gate and the solidified layer on the outside circumferential surface of cooling rolls separable. CONSTITUTION:A titled device consists of a pair of cooling rolls 1, a driving means for rotating the rolls 1, and a gate 3 provided to prevent the leakage of molten steel. Said gate 3 is formed with two openings 9 having the same length as the axial length of the rolls 1 in the part where the gate contacts with the molten metal supplied into a molten steel well 2 and is in proximity to the outside circumferential surface of the rolls. Gaseous pressure is supplied through the communicating hole 10 formed in the gate 3 to the openings 9. The connection of the solidified shell 4a on te outside circumferential surface of the rolls and the solidified layer 4b formed on the inner side surface of the gate 3 is prevented by the above-mentioned device, and the cast plate having the good surface characteristics is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuous casting apparatus for steel sheets that can stably obtain good surface properties.

Conventionally, as shown in Fig. 1, a device for directly casting steel plates from molten steel has been equipped with a pair of cooling rolls 1 having the same length, the same diameter, and the same diameter, their axes being horizontal and parallel to each other, and close to each other. In order to prevent molten steel from leaking, the molten steel reservoir 2 is brought close to both axial ends of the outer peripheral surface of each of the pair of cooling rolls 1 in cooperation with a part of the outer peripheral surface of each of the pair of cooling rolls 1. using weir 3 to form,
A pair of cooling rolls 1 are rotated in opposite directions.

The molten steel 4 injected into the molten steel reservoir 2 is brought into contact with the outer peripheral surfaces of the pair of cooling rolls l rotating in opposite directions to solidify it, and thus the molten steel 4 is solidified on the outer peripheral surface of each of the pair of cooling rolls l. During one rotation of the obtained pair of solidified shells, the pair of cooling rolls is placed in the closest position to the surface cooling roll 1.
An apparatus is known in which the cast plates 4' are pressed against each other and taken out from the roll gap as a cast plate 4'.

However, although such a configuration has the advantage that the configuration of the weir 3 is simple, the upper surface (molten metal surface) of the molten steel bath formed in the molten steel pool 2 does not come into direct contact with the outer peripheral surface of the cooling roll l. ing. Therefore.

It is practically unavoidable that the molten metal level changes and the contact position between the outer peripheral surface of the cooling roll l and the molten metal surface changes due to the flow of the molten steel 4. The solidification start point becomes unstable, which adversely affects the surface quality of the cast plate 4'.

Therefore, as shown in Fig. 2, the pair of cooling rolls l are placed close to the upper part of the outer peripheral surface and both axial ends of each of the pair of cooling rolls l to prevent molten steel from leaking. The molten steel formed in the molten steel sump 2 is used to form a molten steel sump 2 in cooperation with a part of the outer peripheral surface of each roll 1. An apparatus has been proposed in which the molten steel 4 is brought into stable contact with the outer circumferential surface of the cooling roll 1 by setting the level of the bath at a higher level than the cooling roll 1.

However, such conventional continuous casting equipment has the following problems. Namely 1. FIG. 3 is a sectional view showing a part of the outer circumferential surface of the cooling roll 1 and a weir 3 adjacent to the outer circumferential surface of the cooling roll 1 in a conventional continuous casting apparatus. As shown in the figure, the molten steel 4 injected into the molten steel reservoir 2 comes into contact with the outer peripheral surface of the cooling roll 1 rotating in the direction of the arrow, and a solidified layer 4a is formed thereon. The solidification starting point of the solidified layer 4a on the outer peripheral surface of the cooling roll 1 is near the lower end portion of the weir 3 which is close to the outer peripheral surface of the cooling roll 1.

The molten steel 4 in the molten steel reservoir 2 also comes into contact with and solidifies on the inner surface of the weir 3, and a solidified layer 4b is formed there. On the other hand, between the outer peripheral surface of the cooling roll l and the weir 3.

There is a gap (for example, about 0.51 JI). Therefore,
During casting, the solidified layer 4b formed on the inner surface of the weir 3 and the solidified layer 4μ formed on the outer peripheral surface of the cooling port L during one rotation are connected. ! For this reason,
Once the two are connected, the connected part is connected to the cooling roll 1.
It is cut as the blade rotates. As a result, immediately after cutting, the molten steel 4 suddenly comes into contact with the portion of the outer peripheral surface of the cooling roll l upstream of the cut portion, so that the solidified layer 4a on the outer peripheral surface of the cooling roll 1 solidifies. The starting point tends to be unstable. Therefore, it is difficult to obtain a cast plate 4' with good surface properties.

The present invention has been made to solve the above-mentioned problems, and includes a pair of cooling rolls, a driving means for rotating the pair of cooling rolls in opposite directions, and a drive means for rotating the pair of cooling rolls in opposite directions, and a mechanism that prevents molten steel from leaking. In a continuous casting apparatus for steel sheets having a weir, the weir includes a part of the pair of cooling rolls close to the outer circumferential surface of each of the pair of cooling rolls so as to be in contact with the molten steel supplied into the molten steel reservoir. two openings each having a length substantially the same as the axial length of each of the two openings are formed, and a solidified shell on the outer circumferential surface of each of the pair of cooling rolls is formed on the outside of the weir; A gas supply means for supplying gas pressure to the opening is connected through a communication hole formed in the layer so as not to be connected to the solidified shell of the dam.

The present invention will be described below with reference to embodiments and drawings. .

Fig. 6 is a plan view of a continuous steel plate casting apparatus according to the present invention, Fig. 5 is a sectional view of a cooling roll in the same apparatus, and Fig. 6 is a sectional view of a cooling roll in the apparatus.
The figure is a sectional view showing the outer circumferential surface of the cooling roll and part of the weir in the same apparatus.

In the figure, ■ indicates a pair of cooling rolls that are close to each other, and the pair of cooling rolls 1 have the same length and the same diameter, and their axes are horizontal and parallel to each other. A pair of cooling rolls 1 are rotated by a driving means (not shown) in opposite directions, that is, in a direction in which their respective outer peripheral surfaces are descending at the same peripheral speed at the portion where their respective outer peripheral surfaces are closest to each other.

As shown in FIG. 5, the peripheral wall 1a of each of the pair of cooling units 2 and 1 is made of a metal having high thermal conductivity (for example).

The cooling medium passage 5 is made of copper (copper or copper alloy), and a cooling medium passage 5 is formed therein in a continuous spiral manner in the circumferential direction. The cooling medium such as water or high boiling point heat medium is the shaft of the cooling roll 1 (hollow shaft, however).

The middle part is closed) 6 is supplied from one end of the cooling medium passage 5 through a supply pipe 7 to one end of the cooling medium passage 5 located at one end of the peripheral wall 1a, and then passed through the supply pipe 7 to the other end of the peripheral wall 1a. The coolant reaches the other end of the coolant passage 5 located at , from where it passes through a discharge pipe 8 and is discharged to the other end of the shaft 6 . Therefore, the molten steel that has come into contact with the outer peripheral surface of the cooling roll 1 is solidified by exchanging heat with the cooling medium supplied into the cooling medium passage 5 of the peripheral wall 1a (cooled).

3 cooperates with a part of the outer circumferential surface of each of the pair of cooling rolls l by placing it close to the upper part of the outer circumferential surface of each of the pair of cooling rolls 1 and both ends in the axial direction to prevent the steel from leaking. This is a weir formed into a substantially cylindrical shape for forming a molten steel reservoir 2.

As shown in FIG. 6, at the weir 3. A portion close to the outer peripheral surface of each of the pair of cooling rolls 1 (only one is shown in the figure, but the same applies to the other) is supplied into the molten steel pool 2 from above by a molten steel supply means (not shown). An opening 9 having substantially the same length as the axial length of the cooling roll 1 is formed so as to be in contact with the molten steel 4 .

As shown in FIGS. 4 and 6, in the weir 3.

A communication hole 10 is formed through the weir 3 so that one end communicates with the opening 09 and the other end opens on the outer surface of the weir 3. At one end of the communication hole 10 on the outside of the weir 3, a pressure gas supply (not shown) is provided. One end of the pipe 11 from the source is connected.Therefore, when gas is supplied from the pressure gas source to the opening 9 through the entire communication hole 10, the molten steel 4 in contact with the opening 9 will be blown as shown in FIG. , the gas does not enter into the opening 9 more than necessary.Moreover, the gas does not flow between the part 3a of the weir 3 closest to the cooling roll l and the outer peripheral surface of the cooling roll l and the molten steel 4 attached thereto. The outflow gas prevents the molten steel 4 from coming into contact with the part 3a.Therefore, the molten steel 4 that is in contact with the opening 0.9 smoothly flows down and rotates. The solidified layer 4b formed on the inner surface -F of the weir 3 and the solidified layer 4a formed on the outer peripheral surface of the cooling roll 1 are in contact with each other. Therefore, the solidification origin of solidification 4a on the outer circumferential surface of the cooling roll I is stabilized.As a result, a cast plate with good surface properties can be obtained.

As explained above, in this invention, the coagulated layer at the inner lower end of the weir and the coagulated layer on the outer circumferential surface of the cooling roll are influenced by each other by supplying gas through the openings formed in the weir. It is possible to obtain a cast plate with good surface properties by separating and blowing to stabilize the solidification origin of the solidified layer on the outer peripheral surface of the cooling roll.

[Brief explanation of the drawing]

1 and 2 are front and side views of a conventional continuous casting apparatus for steel plates, and FIG. 3 is a view of the same apparatus. FIG. 4 is a cross-sectional view showing the outer circumferential surface of the cooling roll and a part of the weir, and FIG. 4 is a plan view of the continuous casting apparatus for steel sheets according to the present invention. Figure 5 is a cross-sectional view of the cooling U-rule in the same device.
The figure is a sectional view showing the outer circumferential surface of the cooling roll and part of the weir in the same apparatus. 1... Cooling roll, 2... Molten steel sump, 3... Weir, 9...
・Opening. Applicant: Nippon Kokan Co., Ltd. Agent Keita Tsutsumi (1 person) *1 Figures 2-3 Figure 4 Figure 5 Figure 6

Claims (1)

[Scope of Claims] A continuous casting apparatus for steel sheets having a weir that prevents molten steel from leaking, wherein the weir is arranged so that each of the pair of cooling rolls is in contact with the molten steel supplied into the bath steel pool. Two openings 1] having substantially the same length in the axial direction as each of the pair of cooling rolls are formed in a portion close to the outer circumferential surface. On the outside of the weir, the opening is inserted through a communicating hole formed in the layer so that the solidified shell on the outer peripheral surface of each of the pair of cooling rolls is not connected to the clay solidification process (1) of the clay. A continuous casting apparatus for steel sheets, characterized in that a gas supply means for supplying gas pressure is connected to the apparatus.