JPH06269911A - Method for casting extra thin cast strip and its apparatus - Google Patents

Abstract

PURPOSE:To stably obtain a cast strip having comparatively thick and amorphous state by making the cooling capacity of one of rolls rather low, flowing down a molten metal onto the surface of this roll, rapidly solidifying the molten metal at the time of contacting with the other roll and discharging as the cast strip from a gap between the mutual rolls. CONSTITUTION:The molten metal M is supplied on the surface of the cooling roll 4a having low cooling capacity so as not to generate the solidified shell. At almost the same time of bringing this molten metal into contact with the other roll 4b having high cooling capacity, the solidified shell generated by this contact is intensely pressed in a gap between the mutual rolls. As a result, extremely high heat is generated and even in the case of the comparatively thick cast strip, this cast strip can be made to be perfect amorphous. Therefore, in the casting of the thin cast strip by a twin roll casting device, the strip thickness can be increased without deteriorating the quality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing an extremely thin cast piece such as an amorphous material by using a twin roll type casting apparatus.

[0002]

2. Description of the Related Art As a facility for producing an extremely thin cast slab such as amorphous, a single roll type casting facility equipped with a single cooling roll is known.

In this single roll type casting equipment, the molten metal is smoothly injected into the roll surface of the cooling roll through a slit-shaped nozzle, and the molten metal is rapidly solidified on the roll surface (solidification at the portion in contact with the cooling roll. Is started, and solidification is completed in the vicinity because the thickness is as thin as several tens of μm.)

By the way, in the production of an extremely thin cast piece using such a casting equipment, even if an attempt is made to produce a slightly thick cast piece having a thickness of more than 50 μm, the cooling rate is low, so that a critical point for amorphization is required. The cooling rate was not reached, and there was a drawback that it was difficult to obtain a completely amorphous cast slab.

In order to solve the above problems, for example, Japanese Patent Laid-Open No. 61-63346 discloses a multi-stage slit type nozzle having a plurality of slit-shaped openings spaced in the moving direction of a cooling body. Although a method for producing a metal ribbon using the method is disclosed, it is difficult to process the nozzle tip used for carrying out this method, and the nozzle life is short and nozzle clogging easily occurs, so stable casting is possible. Was difficult to implement.

Regarding the production of thin-walled thick cast slabs,
Twin roll casting equipment with a pair of cooling rolls spaced apart from each other is used. (The kiss part of the roll is supplied by feeding molten steel into the gap between the rolls. () Will almost complete the solidification)
However, according to this, since the thickness of the cast slab generated while passing through the molten metal pool between the cooling rolls becomes large, it is not possible to obtain a critical cooling rate for amorphization.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to propose a method and an apparatus for stably obtaining a relatively thick slab which is also amorphous.

[0008]

SUMMARY OF THE INVENTION The present invention is intended to produce an extremely thin cast piece by using a twin roll type casting device, by lowering the cooling ability of one roll of the above device, and by making the roll surface of this roll. It is a method for casting an ultra-thin cast piece, characterized in that a molten metal is flown down onto it, and when it comes into contact with the other roll, it is rapidly solidified and discharged as a cast piece from between the rolls.

Further, the present invention is a casting apparatus equipped with a pair of cooling rolls which rotate in opposite directions to rapidly solidify the molten metal flowing down on the surface thereof, and one of the cooling rolls comprises: It is a twin roll type continuous casting device characterized in that it has a lower cooling capacity than the other roll.

Of the pair of cooling rolls, the roll having a low cooling capacity is particularly preferably provided with a ceramic or a low thermal conductive member having extremely low heat conduction on the roll surface. Further, a roll having a low cooling capacity is advantageously suitable as a roll having a heating means and further provided with an adjusting mechanism capable of adjusting a clearance between the rolls.

[0011]

[Function] Factors that control the cooling rate of molten metal are:
The heat transfer coefficient at the contact portion between the cooling roll and the cast piece has the greatest effect. By the way, in the method using a single roll, it is not possible to apply a pressing force for improving heat transfer between the solidified shell generated from the vicinity of the point of contact with the roll surface and the roll surface, and the thick wall of the slab When such an operation is carried out, it cannot be made amorphous and desired properties cannot be obtained when such a plate is commercialized (such as a transformer core).

In the present invention, when molten metal is supplied to the roll surface of a roll having a low cooling capacity so as not to form a solidified shell, this molten steel is brought into contact with the other roll (roll having a high cooling capacity). At the same time, the solidified shell generated by this contact was pressed firmly in the gap between the rolls (hereinafter, this gap is referred to as the roll kiss portion), so extremely high heat removal occurred and the cast piece was relatively thick. However, it can be made completely amorphous.

FIG. 1 shows the structure of a casting apparatus according to the present invention. In the figure, 1 is a tundish for containing molten metal, 2 is a pipe for supplying molten metal M to the tundish 1 (seal pipe). Etc.) 3 is tundish 1
The slit-shaped nozzles 4 for supplying the molten metal therein to the cooling rolls are cooling rolls for rapidly solidifying the molten metal M supplied from the nozzles 3. One of the cooling rolls 4a is, for example, a roll. The surface is made of ceramic or the like having extremely low heat conductivity, and has a lower cooling capacity than the other roll 4b in which cooling water is forcibly cooled.

Numeral 5 is a means for heating the cooling roll 4a. As the heating means 5, for example, a burner or the like (a type in which heat is generated by energization may be used) is applied. 6 is a molten metal pool formed between the rolls 4a and 4b, 7 is a cast piece, and 8 is a cast piece 7 from the cooling roll 4b.
Is an air knife for peeling off the peeled slab 7, a belt conveyor for conveying the peeled slab 7, and 10 is a suction device for bringing the peeled slab 7 into close contact with the belt conveyor 9.

When the molten metal M in the tundish 1 is supplied onto the cooling roll 4a through the slit-shaped nozzle 3, the molten metal M partially or wholly remains in a molten state and the kiss portions of the rolls 4a and 4b are kissed with each other. Flows into the pool and forms a pool (paddle).

Since both rolls 4a and 4b rotate at a high speed, a solidified shell is formed on the surface of roll 4b having a high cooling capacity when molten metal M passes through this pool 6. Then, the solidified shell is pressed by the roll kiss portions by the roll surfaces of the rolls 4a and 4b, and at this time, the solidified shell is cooled at an extremely high speed (a high heat transfer coefficient is secured) sufficient to become amorphous. The slab 7 separated from the cooling roll 4b passes through a belt conveyor 9 and is wound into a coil by a winding device arranged thereafter.

In the present invention, the roll 4a having a low cooling capacity is heated to a sufficiently high temperature in advance so that a solidified shell of the molten metal M is not formed by this roll, and is stably expanded to have a constant thickness. It is possible to obtain a cast slab.

The heating temperature depends on the composition of the cast slab to be cast, but the roll surface temperature is preferably about 500 to 1000 ° C. In addition, such a roll with low cooling capacity,
Use a ceramic roll with excellent heat resistance and wear resistance,
Alternatively, a structure in which ceramic is sprayed on the surface of the roll is particularly advantageous.

The thickness of the slab obtained by the above casting apparatus can be easily changed by adjusting the roll interval between the rolls 4a and 4b by a clearance adjusting mechanism (not shown) provided with a driving means such as a hydraulic cylinder. . In this invention, casting under a reduced pressure atmosphere is advantageous for improving the surface properties of the slab.

[0020]

EXAMPLE A twin-roll type casting apparatus as shown in FIG. 1 above.
(Synthetic mullite ceramic as a roll with low cooling capacity
Using a roll (heated to 800 ° C), use Fe₇₈B₁₈
Si ₉(Atomic%) system molten steel (amorphous alloy)
Degree 30m / sec, Roll rotation speed 19.1 RPS, Roll mutual
A slab with a thickness of 80 μm was obtained by casting under a clearance of 85 μm.
The quality and casting conditions of the manufactured and obtained ingots are controlled.
I checked.

As a result, the casting condition was stable, and the obtained slab was cast while changing the thickness to a maximum of 95 μm, but in that range the total thickness was amorphized and the iron loss was extremely low. It was confirmed that it was possible to obtain a slab. In this example, by setting the casting atmosphere to a reduced pressure atmosphere of about 10 kpa, it was possible to obtain a smooth cast slab with no unevenness on the surface.

[0022]

As described above, according to the present invention, it becomes possible to increase the plate thickness in the casting of a thin cast piece by the twin roll type casting device without deterioration of quality.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an apparatus according to the present invention.

[Explanation of symbols]

 1 Tundish 2 Pipe 3 Slit Nozzle 4 Cooling Roll 5 Heating Means 6 Hot Water Pool 7 Cast Piece 8 Air Knife 9 Belt Conveyor 10 Suction Device

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Toru Sato 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Inside the Chiba Steel Works (72) Inventor Kenji Nakagawa 1 Kawasaki-cho, Chuo-ku, Chiba-shi Kawasaki Steel Works Co., Ltd. Chiba Steel Works (72) Inventor Shun Suhara 1 Kawasaki-cho, Chuo-ku, Chiba, Chiba Prefecture Kawasaki Steel Works Chiba Works (72) Inventor Katsumi Kurokawa 1 Kawasaki-cho, Chuo-ku, Chiba City Kawasaki Chiba Steel Works, Ltd.

Claims (5)

[Claims] 1. When manufacturing an ultra-thin cast piece by using a twin roll type casting device, the cooling ability of one roll of the above device is lowered,
A method for casting an ultra-thin cast piece, characterized in that molten metal is made to flow down on the roll surface of this roll, and when it comes into contact with the other roll, it is rapidly solidified and discharged as a cast piece between the rolls. 2. A casting apparatus equipped with a pair of cooling rolls which rotate in opposite directions and rapidly solidify the molten metal flowing down on the surface thereof and discharge the molten metal from between the rolls. One is a twin roll type casting device, which is a roll having a lower cooling capacity than the other roll. 3. The apparatus according to claim 2, wherein the roll having a low cooling ability is provided with a ceramic or a low heat conductive member having extremely low heat conduction on the roll surface. 4. The apparatus according to claim 2, wherein the roll having a low cooling ability has a heating means. 5. An apparatus according to claim 2, 3 or 4, further comprising an adjusting mechanism capable of adjusting a clearance between the rolls.