KR20040056263A - A device for controlling the gas flow in twin roll strip caster - Google Patents

Abstract

PURPOSE: A device for controlling gas flow in twin roll strip caster is provided which is capable of casting a strip having uniform thickness by controlling flow and distribution of gas injected onto a position where the surface level of molten steel and casting rolls are starting contacting with each other. CONSTITUTION: In a twin roll strip caster(100) comprising a pair of casting rolls(1), a molten steel supplying submerged entry nozzle(3) for supplying molten steel to form molten steel pool between edge dams(5) installed at both ends of the pair of casting rolls, a gas supply nozzle(9) for supplying inert gas into meniscus shield(8) for covering an upper part of the molten steel pool, and weirs(10) a lower end of which is dipped into the molten steel pool so that a casting slab is casted by rotating the casting rolls in such a direction that the casting rolls are engaged with each other, the device(50) for controlling gas flow in the twin roll strip caster comprises a plural gas control plates(51) vertically slidingly assembled into guider of the meniscus shield and vertically installed in a width direction of the casting rolls between the gas supply nozzle and the weirs; and driving members(55) for vertically moving the gas control plates to adjust a gap between a lower end of the gas control plates and the outer circumferential surface of the casting rolls.

Description

A / V DEVICE FOR CONTROLLING THE GAS FLOW IN TWIN ROLL STRIP CASTER}

The present invention is to control the flow and distribution of the gas injected from the position where the hot water surface and the casting rolls meet to form a uniform temperature distribution over the entire width of the casting roll in a twin roll sheet casting machine for casting the cast between a pair of casting rolls The present invention relates to a gas flow control apparatus for a twin roll sheet casting machine capable of casting a cast of uniform thickness.

In general, a twin-roll thin caster 100, as shown in Figure 1, between the pair of rolls (1) rotated in different directions and the edge dam (5) mounted on both ends of the tundish (2) The molten steel is supplied through the discharge port 3a of the immersion nozzle 3 attached thereto to form a molten steel pool surrounded by the roll 1 and the edge dam 5.

Then, the molten steel in contact with the roll 1 forms a solidification cell 7 on the surface of the roll 1 while losing heat in the direction of the center of the roll, and by the roll 1 rotating in opposite directions to each other. Casting is performed as the cast piece exits the roll shop.

Here, the meniscus shield (8) is installed in the upper portion of the molten steel pool to prevent the inflow of air from the outside in order to prevent the molten steel from being oxidized by contact with the atmosphere. The inert gas is supplied to the hot water surface of the molten steel pool through the gas supply nozzle 9 installed in the molten steel pool so that the top surface of the hot water surface is maintained in an inert atmosphere.

In addition, the momentum of the molten steel discharged from the discharge port (3a) of the immersion nozzle (3) is so large that the upper surface of the meniscus shield (8) to control the flow of the molten steel to prevent the molten steel pool is rocking It is fixed, the weir 10, the lower end is immersed in the molten steel pool is installed.

Here, while casting the thin plate using the twin-roll thin caster 100, while trying to maintain the atmosphere on the hot water surface of the molten steel pool in an inert atmosphere as much as possible, it is difficult to secure 100% sealing (seal) and partially oxide There is a possibility to be produced in the hot water surface, the weir (10) also serves as a kind of barrier (barrier) to prevent the generated oxide to reach the growing coagulation cell (7).

However, it is necessary to adjust the crown formed on the surface of the roll or to adjust the surface roughness of the roll 1 and additional processing in order to obtain a quality slab having a uniform temperature distribution, that is, uniform quality, over the roll width. It is difficult to expect satisfactory results with these measures alone.

On the other hand, nitrogen gas, which is an inert gas supplied to maintain the hot water surface in an inert atmosphere, has a great influence on the curve formation of the molten steel formed at the place where the hot water surface surface and the main sol roll 1 contact as shown in FIG. When the curved shape is changed, the amount of nitrogen gas absorbed into the molten steel is changed, and finally, the heat flux is changed by the casting roll 1. Accordingly, if the curved shape can be artificially changed by the inert gas in the region where the heat flux is small locally, the heat flux can be increased, and finally, it is possible to obtain a uniform cast over the entire width of the cast steel.

In addition, as shown in Figure 3, the process of casting a thin plate by a twin-roll type sheet casting machine, unlike the conventional continuous casting process, because it does not use flux on the surface of the hot water, such as manganese (Mn) This material vaporizes and adheres to the surface of the casting roll 1, which causes a slight change in the thickness layer of the black skin attached to the roll surface, which also causes a decrease in heat flux. Accordingly, in order to obtain a uniform cast in the slab width direction by adjusting the heat flux change due to the vaporizable substance, an inert gas gas flow adjusting apparatus capable of controlling the flow of such vaporizable substance is required.

Reference numeral 6 in FIGS. 1 and 2 denotes cooling holes through which cooling water is circulated and supplied to cool the casting roll 1.

Accordingly, the present invention has been proposed to solve the above conventional problems, the object of which is the flow of inert gas supplied to the space between the meniscus shield and the molten steel pool to form a uniform cooling capacity over the entire width of the cast steel And to control the distribution in the roll width direction to provide a gas flow control device of a twin-roll sheet caster that can finally cast a cast of a uniform thickness.

1 is a schematic view showing a typical twin roll sheet casting machine,

Figure 2 is a schematic diagram showing the flow of inert gas on the surface of the casting roll,

3 is a schematic diagram showing the evaporated manganese fume flow in the molten steel pool;

Figure 4 is a block diagram showing a gas flow control device of a twin-roll sheet caster according to the present invention,

Figure 5 is a side view showing a gas flow control device of a twin roll sheet caster according to the present invention,

Figure 6 is a plan view showing a gas flow control device of a twin-roll sheet caster according to the present invention,

Figure 7 (a) (b) is a front view showing a gas distribution plate employed in the gas flow control apparatus of a twin roll sheet caster according to the present invention,

Figure 8 (a) (b) (c) is a graph showing the casting results when the center portion of the gas control plate is arranged high,

Figure 9 (a) (b) (c) is a graph showing the casting results when the center portion of the gas control plate is arranged low.

Explanation of symbols on the main parts of the drawings

1 ..... Casting Roll 5 ...... Edge Dam

8 ..... Maniscus Shield 9 ...... Gas Supply Nozzle

10 .... Weir 51 ..... Gas throttle

52 .... Guider 53 .... Through Hole

54 .... rack gear 55 .... drive member

56 .... Pinion Gear 59 .... Stopper

As a technical configuration for achieving the above object, the present invention,

A molten steel supply immersion nozzle for supplying molten steel to form a molten steel pool between a pair of casting rolls and edge dams provided at both ends thereof, and for supplying inert gas into the meniscus shield covering the upper portion of the molten steel pool. In the twin-roll type sheet casting machine having a gas supply nozzle and a weir in which a lower end is immersed in the molten steel pool to rotate the casting rolls in engagement with each other to cast the cast steel,

A gas adjusting plate which is assembled to the guider of the meniscus shield so as to be movable up and down and is installed in the width direction of the casting roll vertically between the gas supply nozzle and the weir;

By providing a gas flow control device for a twin-roll sheet caster comprising a; drive member for moving the gas control plate to move the distance between the lower end of the gas control plate and the outer peripheral surface of the casting roll.

Hereinafter, the present invention will be described in more detail.

Figure 4 is a block diagram showing a gas flow control apparatus of a twin roll sheet caster according to the present invention, Figure 5 is a front view showing a gas flow control apparatus of a twin roll sheet caster according to the present invention, Figure 6 Figure 2 is a plan view showing a gas flow control apparatus of a twin-roll sheet casting machine.

As shown in Figs. 4 to 6, the apparatus 50 of the present invention passes the molten steel of the molten steel pool formed between the pair of casting rolls 1 and the edge dam 5 facing each other, and casts the cast steel. In the casting machine 100 to control the flow and distribution of the inert gas supplied to the casting roll (1) and the molten steel of the molten steel pool in the width direction so that the molten steel of the molten steel pool is maintained in an inert atmosphere, the coagulation capacity is uniformly formed over the width of the cast steel. As such, the device 50 is composed of a gas adjusting plate 51 and a drive member (55).

That is, the gas control plate 51 is mounted on the meniscus shield 8 covering the upper portion of the molten steel pool so that the lower end is immersed in the molten steel pool and the gas supply nozzle 9 for supplying an inert gas to the molten steel pool. Between the weirs 10, the upper end of which is fixed to the varnish shield 8, a plurality of plate members are installed vertically in the width direction of the cast steel.

The gas regulating plate 51 is formed with a groove 58 so as to be slidably assembled to the guider 52 having a 'T' cross section, and the guider 52 has an upper surface of the meniscus shield 8. It is mounted on the inner surface of the through hole 53 penetrating in the slab width direction.

In addition, a plurality of gas control plates 51 disposed in the slab width direction between the gas supply nozzles 9 and the weirs 10 are too close to the gas supply nozzles 9 so that the gas control plates 51 and the casting rolls ( 1) the molten steel of the molten steel pool casting roll (1) so as not to reduce the range that can adjust the vertical gap between, the gas control plate 51 is closer to the weir (10) so that the molten steel of the molten steel pool is not fixed to the outer surface (1) It is preferably installed at a position 45 to 75 mm away from the interface bordering the).

And, as shown in Fig. 7 (a), the gas control plate 51 has a center so that the supply speed of the inert gas supplied to both side portions of the slag with a low coagulation capacity can be formed faster than the central portion of the slab with a high coagulation capacity. The plate member 51a for adjustment and the plate member 51b for edge adjustment disposed on both left and right ends thereof, and as shown in FIG. 7 (b), the plate member 51a for the central adjustment is formed on the center plate. 51c and 51 d of auxiliary plate members arrange | positioned at the left and right ends.

The plate members 51a, 51b, 51c, 51d, and 51e are each provided with driving members 55 so as to individually adjust the distance between the lower end and the outer circumferential surface of the casting roll 1 to operate independently. .

In addition, the driving member 55 adjusts the distance h between the lower end of the gas control plate 51 and the outer circumferential surface of the casting roll 1 and the casting roll 1 by the flow of gas passing therethrough. It is possible to control the shape of the molten steel curve formed in the place where the molten steel is in contact.

Here, the distance h is preferably maintained to about 5 to 20mm, the drive member 55 is a pinion gear 56 is meshed with the rack gear 54 mounted on the front of the gas control plate 51. ) Is composed of a motor member mounted at the end of the drive shaft.

Accordingly, when the gas regulating plate 51 is moved by rotating in the forward or reverse direction of the pinion gear 56, the distance h between the lower end of the gas regulating plate 51 and the outer peripheral surface of the casting roll 1 Since the gas is widened or narrowed, the gas control plate 51 is lowered in the region where the gas velocity is to be high, and the gas control plate 51 is raised in the region where the gas velocity is to be reduced and supplied from the gas supply nozzle 9 to the molten pool side. The flow rate and distribution of the inert gas can be properly adjusted in the width direction of the cast steel.

In addition, the driving member 55 may be replaced with a reciprocating cylinder that is connected to the gas control plate 51 and the rod end to transfer the gas control plate 51 in the vertical direction, and is not limited to this. Means may be employed.

The drive member 55 is preferably fixed to the upper portion of the meniscus shield (8) by a fixing means such as a separate fixing bracket.

In addition, a lower control stopper 59 is mounted on a rear surface of the gas control plate 51 so that the lower end of the gas control plate 51 which is moved up and down in the guider 52 and the outer circumferential surface of the casting roll 1 do not interfere with each other. It is preferable.

As shown in FIG. 8 (a), when the casting operation is performed in a state in which the gas adjusting plate 51 is disposed so that the rising height of the central adjusting plate member 51a is higher than the edge adjusting plate member 51b, Since the gas flow rate supplied to the center portion of the slab is slower than the gas flow rate supplied to both edge portions of the slab, as shown in FIG. 8 (b) (c), the temperature distributions at both edges and the center of the slab become almost similar. It can be seen that the delta-ferrite distribution appears almost uniform across the entire width of the slab.

Here, for reference, the low delta-ferrite value indirectly indicates that the slag solidification ability is large in the region.

On the other hand, as shown in Fig. 9 (a), when the gas adjusting plate 51 is disposed so that the rising height of the center adjusting plate member 51a is lower than the edge adjusting plate member 51b, Fig. 9 (b) ( As shown in c), the temperature at the center of the slab is measured lower on both edges of the slab by a CCD camera or a non-contact temperature measuring sensor between the casting roll and the looper equipment, and the delta-ferrite value. In addition, the center of the slab shows a much lower value than the edge of the slab, which shows a fairly non-uniform delta ferrite distribution over the entire width of the slab.

According to the present invention as described above, between the gas supply nozzle for supplying the inert gas and the weir that the lower end is immersed in the molten steel pool, a plurality of gas throttling plate is divided into the central portion and the two edge portions of the slab in the slab width direction. By controlling the flow and distribution of the gas, it is possible to have a uniform cooling ability over the cast slab width to be cast, so that an effect of finally producing a cast of uniform thickness is obtained.

While the invention has been shown and described with respect to specific embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit or scope of the invention as set forth in the claims below. I would like to clarify that knowledge is easy to know.

Claims (6)

A molten steel supply immersion nozzle for supplying molten steel to form a molten steel pool between a pair of casting rolls and edge dams provided at both ends thereof, and for supplying inert gas into the meniscus shield covering the upper portion of the molten steel pool. In the twin-roll type sheet casting machine having a gas supply nozzle and a weir in which a lower end is immersed in the molten steel pool to rotate the casting rolls in engagement with each other to cast the cast steel, A gas regulating plate which is assembled to the guider of the meniscus shield so as to slide vertically and is installed vertically in the width direction of the casting roll between the gas supply nozzle and the weir; And a driving member for moving the gas adjusting plate so as to adjust the distance between the lower end of the gas adjusting plate and the outer circumferential surface of the casting roll. 2. The method of claim 1, The gas control plate is a gas flow control device of a twin roll sheet caster, characterized in that the molten steel of the molten steel pool is installed at a position spaced 45 to 75 mm from the boundary surface in contact with the casting roll. The method of claim 1, The gas control plate is a gas flow control device of a twin-roll thin plate casting machine, characterized in that consisting of a central control plate member and the edge control plate member disposed on the left and right ends thereof. The method of claim 3, wherein The central control plate member is a gas flow control device of a twin-roll thin plate casting machine, characterized in that consisting of the plate member for the central control and the auxiliary plate member disposed on the left and right ends thereof. The method of claim 1, The driving member is a gas flow control device of a twin roll sheet caster, characterized in that consisting of a rack gear mounted on the front of the gas control plate and a motor member mounted to the drive shaft end of the pinion gear to be engaged. The method of claim 1, The gas flow control apparatus of the twin roll type sheet caster, characterized in that the lower end of the gas control plate and the lower end and the outer peripheral surface of the casting roll is mounted on the rear of the gas control plate so as not to interfere with each other.