JPS60210342A - Casting method of thin metallic sheet by twin rolls - Google Patents

Abstract

PURPOSE:To maintain a uniform flow rate distribution and to cast a thin metallic sheet having good quality without rippled surfaces, etc. by providing a box- shaped gate formed with notches for outflow of a molten metal on one side face between a nozzle and rolls. CONSTITUTION:The space between a pair of the casting rolls 4 is set at a prescribed distance and thereafter the rolls are rotated at a required speed and the molten metal is poured into said space from the nozzle 1. The molten metal 3 received in the gate 2 overflows from notches 7 on both side faces in the form of the broad thin film-like flow along the axial direction of the rolls and flows down toward the surface of the rolls 4. The molten metal 3 in contact with the rolls 4 is immediately cooled and solidified to form shells. The shells move between the rolls and below the same; at the same time, a molten metal pool is formed by the molten metal supplied successively between the shells. The solidified shells are drawn out below the rolls according to the rotating speed of the rolls and a thin billet 6 is thus obtd.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is a method for continuously casting a thin metal plate by supplying molten metal between a pair of horizontal rolls (twin rolls), and in particular The present invention relates to a casting method capable of supplying a wide and uniform thin film flow to a caster.

(Prior art) Molten metal (for example, molten steel, hereinafter simply referred to as molten metal) is supplied from a nozzle at the bottom of the tundish between a pair of horizontal casting rolls arranged with a gap determined according to the thickness of the slab to be cast, and the horizontal rolls are cooled. A technique for continuously casting thin metal plates by pulling out solidified thin plate slabs downward while driving is known.

When casting with this method, a pouring nozzle is installed between the rolls to supply the molten metal, but the pouring nozzle is
As shown in Japanese Patent No. 9588, it is generally of the type that has a circular cross section and is immersed into the molten metal. However, when trying to cast a wide H piece with a slab width of more than 1 m using such a casting method, the pouring nozzle must be positioned at the center of the slab width direction (casting roll axial direction). Even if the molten metal is poured, the flow velocity distribution of the pouring molten metal in the axial direction of the roll inevitably becomes non-uniform. This non-uniform flow velocity distribution is undesirable because it causes flow wrinkles on the surface of the slab, which leads to deterioration of the surface properties of the slab.

Therefore, in view of the above points, in order to obtain a wide and uniform pouring flow along the roll axis direction as much as possible, it is possible to form the tip of the pouring nozzle into a slit shape, but in the case of molten metal, the pouring flow is The slit width cannot be narrowed due to concerns about interruptions,
This cannot be said to be effective in actual operation. Alternatively, a method of arranging a plurality of nozzles in parallel in the roll axis direction may be considered, but it is disadvantageous in terms of equipment and in terms of operation, it is difficult to pour molten water evenly from all nozzles, and it cannot be said to be effective as well.

In any case, it is not preferable for the properties of the slab to flow directly between the rolls as in the conventional method.

(Object of the Invention) The object of the present invention is to achieve the above-mentioned widening of the pouring flow, uniformity of the flow velocity distribution in the roll axis direction, and thinning of the pouring flow, so that no flow wrinkles occur at all. It is an object of the present invention to provide a casting method using twin rolls capable of casting wide slabs having good surface quality.

(Structure of the Invention) The structure of the present invention for achieving the above object is a casting method in which a pouring nozzle is faced between a pair of horizontal casting rolls to supply molten metal to continuously obtain a thin metal sheet. A box-shaped weir having a notch formed on at least one side through which molten metal flows out is provided between the roll and the roll, and the molten metal from the nozzle is retained in the weir and flows from the notch of the weir to the roll surface. It is characterized by casting by flowing down a wide medium-thin molten metal flow.

In the present invention, the molten metal is not directly injected between the casting rolls from the pouring nozzle as described above, but is first received by the box-shaped weir and then allowed to overflow from there and flow down onto the roll surface. It is possible to easily achieve a wide pouring flow and a thin film flow, and at the same time, it is also possible to make the flow velocity distribution of the pouring flow uniform in the roll axis direction.

(Example) The details of the present invention will be explained below with reference to the drawings. FIG. 1 is a schematic diagram of a twin-roll continuous casting facility for carrying out the method of the present invention, FIG. 2 is a front view thereof, and FIG. 3 is a side view thereof.

As shown in the drawing, a pair of horizontal casting rolls 4 are rotated in the directions of the arrows at set speeds, and are cooled by a suitable water cooling mechanism (not shown). Side dams 5 are provided on the side surfaces of these casting rolls 4 to prevent overflow of the molten metal. Further, a pouring nozzle l for supplying molten metal between a pair of casting rolls 4 extends from the bottom of the intermediate container (tundish) toward between the rolls; 1 box-shaped weir 2 is arranged. In addition, 6 is roll 4
This is the slab that is pulled out below.

The weir 2 is for receiving and retaining the molten metal from the pouring nozzle 1 without directly supplying it between the casting rolls 4, and then allowing the molten metal to flow out onto the roll surface in an optimal condition. The shape has a tapered bottom part slightly inserted between the rolls, a rectangular frame body made of refractory material with a length almost equal to the body length of the casting roll 4, and has an open corner. A rectangular notch 7 is formed on both of the curved sides. Therefore, the molten metal 3 supplied into the weir 2 from the nozzle 1 overflows from the notch 7 as a thin film flow having a width corresponding to the width of the notch. As can be seen from FIG. 2, the tip of the pouring nozzle 1 is installed deep within the weir 2, and is immersed in the molten metal during pouring.

During casting, the pair of casting rolls 4 are set at a predetermined distance, rotated at a required speed, and then a set amount of molten metal is poured from the nozzle. As the pouring from the nozzle continues, the molten metal 3 received in the weir 2 flows out from the notches 7 on both sides of the weir in the form of a wide and thin film flow along the roll axis direction. The bath flow flows down toward the surface of the casting roll 4, as shown in FIG. The molten metal 3 in contact with the rolls 4 is immediately cooled and solidified to form a shell, but since the pair of rolls 4 are rotating in the direction of the arrow, the shell moves between the rolls and below them, and there is a gap between the shells. A molten metal pool is formed by the molten metal that is sequentially supplied. The solidified shell is pulled out below the rolls according to the roll rotation speed, and a thin plate slab 6 is obtained.

In this way, in the present invention, since the molten metal overflows from the notch 7 of the weir 2, a wide thin film flow corresponding to the width of the notch 7 can be easily obtained, but this flow does not flow directly from the nozzle l. There is no flow, and the fluid stays in the tank z and then comes out, so the flow velocity is constant over the entire width, and therefore the flow velocity distribution in the roll axis direction is uniform.

In the illustrated example, the shape of the notch 7 of the weir 2 is square, but the weir may be formed by cutting out the entire width of the side surface, or it may be trapezoidal, in other words, anything that can obtain a thin film flow. It can be of any shape. In addition, although the notches of the weir 2 are formed on both sides in the illustrated example, when the injection amount is not so large as in the case where the roll interval is narrow, I;
may be provided only on one side.

(Effects of the Invention) As explained above, according to the casting method of the present invention, the molten metal flow supplied to the rolls becomes a wide and thin film flow, and the flow velocity distribution becomes uniform in the roll axis direction, resulting in flow wrinkles. etc., and it becomes possible to cast high-quality thin metal sheets.

Furthermore, since the molten metal flow does not flow directly between the rolls, the properties of the obtained slab are also good.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing an example of casting equipment using twin rolls for explaining the casting method of the present invention, Fig. 2 is a front view of the equipment shown in Fig. 1, and Fig. 3 is a side view of the equipment shown in Fig. 1. be. 1...&! Soaked nozzle, 2... Box-shaped weir, 3... Molten metal. 4...Floating casting roll, 5...Side dam, 6...
- Slab, 7...Notch of weir. Patent Applicant Representative Patent Attorney Tomoyuki Yafuki (and 1 other person) Scroll 1 Figure 2N

Claims (1)

[Claims] In a casting method for continuously obtaining a thin metal plate by supplying molten metal between a pair of horizontal casting rolls by facing an injection nozzle, there is a notch between the nozzle and the rolls through which the molten metal flows out on at least one side. Casting is carried out by providing a box-shaped weir with a shape formed therein, allowing the molten metal from the nozzle to stagnate in the weir, and causing a wide, thin film of molten metal flow to flow down from the notch in the weir to the roll surface. A method for casting thin metal sheets using twin rolls.