JPS6257745A - Production of thin sheet - Google Patents

Abstract

PURPOSE:To produce a thin sheet having a uniform thickness and optional width at a high casting speed by dropping a molten metal in the form of a film, blowing gas toward the film-like molten metal flow from a slit nozzle for gas injection to atomize the molten metal and depositing the liquid drops thereof onto rotating rolls. CONSTITUTION:The molten metal 6 in a ladle 1 is dropped in the form of a film onto the rotating twin rolls 5 to form the film-like molten metal flow 3. The gas is blown from the slit nozzle 4 for gas injection having the same width as the width of the molten metal flow 3 or larger than said width toward the molten metal flow to atomize the molten metal to the liquid drops 8. The liquid drops 8 are deposited on the rotating twin rolls 7, by which the thin sheet 9 is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to the field of continuously manufacturing thin plates from droplets with solidified surfaces produced by atomization by blowing a gas onto a molten metal stream. .

(Prior art) Conventionally, Japanese Patent Publication No. 46-43688 and Japanese Unexamined Patent Publication No. 58
As disclosed in Publication No. 218359, macroscopic component segregation is achieved by spraying gas or liquefied gas onto a molten steel flow, causing droplets whose surface only solidifies to fall onto a single roll or twin rolls and accumulate them. There is a technology to directly manufacture thin sheets from molten steel that are completely free of molten steel.

Also, JP-A No. 59-206071 and JP-A No. 59-206071
No. 9-266 discloses a technique in which atomized droplets are scanned in the width direction of the sheet so that the thickness of the manufactured thin sheet is uniform.

(Problem to be Solved by the Invention) However, in the former technique, the molten metal is dropped through a cylindrical nozzle and gas or liquefied gas is sprayed onto this molten metal flow, so the width of the thin plate produced is The thickness in both the casting direction and the casting direction is not uniform, and thin plates with arbitrary widths cannot be manufactured. Furthermore, the flow rate of molten metal is 2
If it is less than 0 kg/min, nozzle clogging will occur, and if the
If the flow rate exceeds kg/min, the efficiency of forming droplets deteriorates rapidly even if a large amount of gas is blown, so the flow rate is limited to 20 to 1000 i/min. Therefore, compared to the current continuous casting method, the casting speed is much slower and there is a problem in productivity.

Furthermore, the latter technique is not completely satisfactory in terms of uniformity of plate thickness, and has not been improved in terms of obtaining an arbitrary plate width and low productivity.

The object of the present invention is to be able to produce thin plates of uniform thickness and arbitrary width when directly manufacturing thin plates from atomized droplets, and to achieve a much slower casting speed than current continuous casting methods. An object of the present invention is to provide a method for manufacturing a thin plate that improves the above.

(Means for Solving the Problems) The present invention involves dropping molten metal into a slit shape and blowing gas onto the film-like molten metal flow, thereby transferring the droplets onto a rotating single roll or twin rolls. A method of manufacturing thin sheets directly from molten metal by deposition.

More specifically, as shown in Fig. 1, molten metal is dropped in a film form by rotating twin rolls 5, and a gas injection slit having a width equal to or larger than the width of the film-like molten metal flow is formed. A method for directly manufacturing a thin plate from molten metal by depositing droplets 8 generated by blowing gas onto a molten metal stream falling in a film form from a nozzle 4 on a rotating twin roll 7 separate from the above-mentioned rolls. be. Even if a metal roll is used while being cooled as a means of forming a film, a solidified shell will adhere to the roll, and as time passes, the distance between the rolls will become narrower and the two rolls will come into contact with each other. The material is BN, which has excellent heat insulation properties and does not form a solidified shell on the roll.
M (J O, etc.) is effective.Furthermore, by rotating the rolls, the roll temperature can be made uniform, and the roll interval'
Since narrowing can be prevented, molten metal can be stably supplied even if the roll interval is made small.

In addition, heating and heat retention are performed to optimize the temperature of the roll.

In the above case, twin rolls are used as means for forming the molten metal into a film, but a slit nozzle 11 as shown in FIG. 2 may also be employed.

(Function) 2 with appropriate spacing to make the molten steel flow into a film.
A case will be described in which molten steel is injected between the rotating rolls of a book.

In the present invention, by lengthening the roll for forming the molten metal flow into a film, it is possible to significantly increase the casting speed. Further, by changing the length of this roll depending on the width of the thin plate to be manufactured, a thin plate of any width can be manufactured.

Furthermore, since the molten metal flow is made to fall in the form of a film, the density of the droplets is uniform when viewed in the length direction of the roll, that is, in the width direction of the plate. Highly uniform thickness.

Furthermore, since the density of the droplets is uniform over time, the thickness is also uniform in the casting direction.

In addition, as shown in Figure 4, if the roll spacing is set to be the same as or smaller than the inner diameter of the conventional cylindrical nozzle, the molten steel can be effectively reduced to droplets by using a smaller amount of gas than in the conventional method. can.

(Example 1) Two BN rolls having a diameter of 2 mm and a length of so mm were rotated, and the roll interval was set to 8 mm, and molten steel was allowed to fall between the rotating rolls. The casting speed at this time was 1500 kg/1Rtn. This film-like molten steel flow is atomized by spraying argon gas from a slit nozzle for gas injection, and the droplets are deposited between two rotating Kinpu rolls located directly below the slit nozzle for gas injection, to a thickness of 2111111. A thin plate with a width of 600+U+++ was produced. At this time, the pressure of the argon gas blown was 15 kg/cd, and the amount of gas 8i was 1100 N 3/
It was l-3teel.

(Example 2) A thin plate with a thickness of 2 mm and a width of 400 mm was manufactured under the same conditions as in Example 1 except that BN rolls with a diameter of 200 mm and a length of 300 mm were used and the roll interval was set to 1 button m.

In both Examples 1 and 2, there was no segregation of components and the internal quality was good. Further, the thickness deviation of the plate was within ±1.5%.

(Comparative Example 1) Molten steel was dropped through a cylindrical nozzle with an inner diameter of 18 mm attached to a tundish, and argon gas was sprayed onto it to atomize it, and the resulting droplets were deposited between two rotating metal rolls to form a 2 mm thick A thin plate was manufactured.

(Comparative Example 2) Molten steel is dropped through a cylindrical nozzle with an inner diameter of 18 mm attached to a tundish, and argon gas is sprayed onto it to atomize it, and the resulting droplets are scanned in the width direction of the plate using a rotating metal twin. Deposited between rolls, thickness 2I
A thin plate of I1m was produced.

In Comparative Example 1, the casting speed was as low as 140 kg/min;
The width of the manufactured plate was as small as 300 nv+, and the thickness deviation was 10% or more. In addition, in Comparative Example 2, the plate width was 5
The thickness was constant at 00 mm, the thickness deviation was 4%, and the casting speed was 140 kg/min, which was inferior to Example 1.2.

Examples and comparative examples of the present invention described above are shown in Table 1.

(Effects of the Invention) As described above, according to the present invention, a thin plate having a uniform thickness and an arbitrary width can be directly manufactured from molten metal at a high casting speed.

[Brief explanation of the drawing]

Fig. 1a shows an apparatus for carrying out the method of the present invention, Fig. 1b is a side view thereof, Fig. 2a shows the case in which the invention is carried out using a slit-shaped nozzle, and Fig. 2b shows the apparatus. The side view, Fig. 3, shows the deviation of the sheet speed obtained by the manufacturing method of the present invention, and Fig. 4 shows the relationship between the molten steel flow rate, molten steel nozzle diameter, and the distance between the refractory twin rolls and the average droplet diameter. It is a diagram. 1... Steel stock or tundish 2... Cylindrical nozzle 3... Film-like molten metal flow 4... Slit nozzle for gas injection 5... Twin rolls 6... Molten metal 7... Twin rolls 8...Droplet 9...Thin plate
10... Weir 11... Slit-shaped nozzle patent applicant Kawasaki Steel Corporation Figure 1a Figure 1b Figure 2a Figure 2b Figure 3 0 θ, 2 0.4 0.6 θ, B
f, 0 version width Figure 4

Claims (1)

[Claims] 1. A method for producing a thin plate from molten metal by atomizing the molten metal by blowing a gas onto the molten metal flow and depositing the resulting droplets on a rotating roll, in which the molten metal is formed into a film. 1. A method for manufacturing a thin plate, comprising: spraying gas onto a film-like molten metal flow from a gas injection slit nozzle to atomize the film-like molten metal flow, and depositing the droplets on a rotating roll. 2. The method according to claim 1, characterized in that the molten metal is formed into a film by rotating twin rolls.