JPH06179051A - Method and device for continuously producing strip - Google Patents

Abstract

PURPOSE:To obtain a metal strip having uniform thickness by pouring a molten metal on casting rolls, generating a solidified shell from the surface, separating a cast strip from the casting rolls without substantially loading rolling reduction force on the obtd. cast strip and successively, executing the rolling reduction to a prescribed thickness with rolling rolls. CONSTITUTION:The rolls 30 for casting and the rolls 32 for rolling are perfectly separated. The casting rolls 30 are controlled to the load so that the rolling reduction force is not loaded to the cast strip or even if the rolling reduction is executed, the rolling reduction force is restrained in the extremely light range or the force loaded to the cast strip becomes the fixed value or below. Therefore, the thickness of the cast strip 18 carried out from the casting rolls 30 is not fixed, and varied. Then this cast strip 18 is cooled with a cooling device 44 to the temp. starting to provide the strength and the ductility and successively, the rolling work is executed to the prescribed strip thickness with the rolling rolls 32. Thus, finally, the sound metal strip can be obtd.

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 continuously producing a thin sheet directly from a molten metal, more specifically, a continuous production of a thin sheet by a twin roll type continuous casting of a thin sheet and a rolling roll. A method and an apparatus therefor.

[0002]

2. Description of the Related Art Conventionally, as a continuous thin plate manufacturing apparatus,
Single roll type and twin roll type continuous casting machines are well known. In the single roll type apparatus shown in FIG. 1 as a representative example, the molten metal 12 from the ladle 10 is supplied to the tundish 14, and the molten metal 12 is injected from the tundish 14 into a casting roll 16 composed of a single roll. Casting is performed. In this method, the slab 18 is not pressed down, so even if the alloy is highly susceptible to cracking at high temperatures, that is, an alloy with low strength and ductility near the freezing point (eg Inconel alloy), it is possible to obtain a slab with relatively no cracking. However, on the other hand, the surface quality on the free surface side is poor, and the shape of the cast slab has large irregularities.

On the other hand, in the twin roll type apparatus shown in FIG. 2 as a typical example, a casting roll 20 composed of a pair of rolls is provided, and the molten metal 12 is directly applied to the casting roll 20 from the ladle 10. Injected. The solidified slab 18 leaves the casting roll 20 from below. Twin roll method, casting roll
Since the solidified shells grown from the surfaces of both rolls of 20 are pressed against each other in the minimum gap of the roll, the surface properties and the shape of the cast piece 18 are better than those of the single roll method.

[0004]

From the original purpose of this type of continuous casting method, the surface property of the cast metal ribbon is small because the work to be performed until the obtained cast piece is made into a final product is slight. It has a great impact on the product. Therefore, the mainstream of the manufacturing method is now becoming the twin roll method.

However, in the case of this twin roll system, it is necessary to control the minimum roll gap and the roll pressing force in order to prevent breakout, slab cracking and fracture, but fluctuations in the molten metal surface due to pouring and growth of the solidified shell cannot be prevented. From uniform to constantly applying appropriate roll gaps and roll pressing forces corresponding to them requires sophisticated control technology. This often results in the control of an excessive amount or an excessively small amount, so that, for example, when an excessive amount of reduction is applied to the slab, cracking or breakage of the slab easily occurs.

Therefore, even so far, a technology combining the control of the pressing pressure and the minimum roll gap, and the casting speed and the molten metal contact length on the roll surface are controlled to realize such control. Many technologies have been disclosed (eg, JP-A-59-193740, JP-A-59-215256, JP-A-3).
-66457).

However, even such a conventional technique cannot effectively prevent slab cracking and fracture, especially in the case of alloys having a high sensitivity to hot cracking. For example, Inconel alloy (
Unlike general-purpose stainless steels such as SUS304 steel, alloys with high sensitivity to hot cracking such as Incoloy alloy (trade name) and Incoloy alloy (trade name) have a slower appearance of strength and ductility in a wide range near the freezing point, and cast rolls. Due to the slight reduction in the minimum gap, the slab surface is likely to crack and break.

FIG. 3 shows Inconel 625 and Incoloy 800.
, And the strength and drawing value of SUS304 near the freezing point. In the case of SUS304, the strength and drawing increase rapidly, but in the former two cases, its development is delayed. That is, unless the solidification is sufficient, the mechanical properties are not sufficient, so that the solidified shell is likely to be cracked or fractured. As described above, it is originally desired to give a large reduction in view of the shape of the slab and the surface quality, but depending on the type of steel, there may be a case where a large restriction is frequently imposed.

The object of the present invention is to solve the above-mentioned problems in the prior art, and it was thought that it was difficult to cast by a twin roll type thin plate continuous casting apparatus until now.
It is an object of the present invention to provide a method and an apparatus capable of continuously producing a sound slab free of surface cracks even in an alloy having high hot cracking susceptibility.

[0010]

In order to achieve the above object, the inventors of the present invention have, as a result of various researches and developments, performed casting instead of rolling down to a predetermined thickness in a casting roll as in the past. Based on the idea that the functions of and reduction are separated, casting is performed by a casting roll as in the past, and reduction is performed by a rolling roll provided downstream, the feasibility is confirmed, and the present invention is completed.

In the present invention, molten metal is poured into a casting roll composed of a single roll or twin rolls to form a solidified shell from the surface, and the resulting cast piece is not substantially loaded with a rolling force. Characterized in that the slab is separated from the casting roll, and then the slab is rolled down to a predetermined plate thickness by a rolling roll composed of one set or a plurality of sets of a pair of rolls arranged in parallel. This is a thin plate continuous casting method.

From another aspect, the present invention comprises a casting roll composed of twin rolls, and a pair of rolls arranged in parallel for rolling down a cast piece separated from the casting roll to a predetermined plate thickness. A thin plate provided with a rolling roll composed of one set or a plurality of sets, and further provided with a mechanism for adjusting a minimum gap of the casting roll so that a load applied to a cast piece in the casting roll becomes a certain value or less. It is a continuous casting machine.

According to a preferred aspect of the present invention, a plate thickness measuring device and a cooling zone may be provided between the casting roll and the rolling roll. Here, the "thin plate" is generally 1-2.
Although it is about mm, in the present invention, it is possible to manufacture up to about 1 to 3 mm.

Thus, according to the present invention, the roll for casting and the roll for rolling are completely separated,
The casting roll does not apply a pressing force to the slab until the slab separates from the roll, or it falls within a very small range even if the slab is pressed, or the load applied to the slab has a constant value. Since the load is controlled so as to be as follows, the casting roll does not need complicated control corresponding to changes in casting conditions, and a sound ribbon can be obtained even with an alloy having high susceptibility to hot cracking.

[0015]

Next, the operation of the present invention will be described in more detail with reference to the accompanying drawings. FIG. 4 is a schematic explanatory view of a thin plate continuous manufacturing apparatus according to the present invention, in which the apparatus is
It comprises a casting roll 30 and a pair of rolling rolls 32 following it.

In the illustrated apparatus, the casting roll 30 is composed of a pair of rolls arranged in parallel, and the rolling roll 32 is composed of a pair of rolls. A load cell 34 and a hydraulic cylinder 36 are incorporated in the casting roll 30, and the minimum gap adjusting mechanism 40 of the casting roll is composed of the load cell 34 and the hydraulic cylinder 36. Here, the function and operation of the adjusting mechanism 40 in the present invention are as follows.

Before casting, a target load is set in advance, for example, 1 kg / mm ²
Then, the controller 41 is set. While the casting is started and the load is detected by the load cell 34, the roll opening is opened and closed by the hydraulic cylinder 36 so as to be within the set value (1 kg / mm ² ). Here, for the purpose of the present invention, it is preferable to set the set value to zero, but if the set value is zero, the roll is infinitely opened and control is impossible. Therefore, the value is set as small as possible within the controllable range. In other words, the state of "substantially applying the rolling force" according to the present invention is set.

Therefore, the adjusting mechanism 40 can easily control so that the load applied to the slab in the casting roll 30 becomes a certain value or less. In the illustrated device, a plate thickness measuring device is provided between the casting roll 30 and the rolling roll 32.
42 and a cooling device 44 are provided. Plate thickness measuring device 42
A command is issued from the control device 46 on the basis of the data from, and the amount of reduction during rolling is controlled by the hydraulic cylinder 50 provided on the rolling roll 32.

Next, the operation of continuously casting a molten metal by this apparatus to continuously produce a thin plate will be described. Ladle
Molten metal 12 contained in 10 is poured between casting rolls 30, and in synchronization with the rotation of a pair of casting rolls 30, a solidified shell grows from the surfaces of both rolls, and a slab is cast from the minimum gap between the rolls. It is sent out as 18.

At this time, the thickness of the solidified shell fluctuates due to fluctuations in the molten metal surface or nonuniform growth of the solidified shell, but according to the present invention, the roll separating force generated in the minimum roll gap is zero by the adjusting mechanism 40. Alternatively, the minimum roll gap is changed so as to be a certain value depending on the steel type. That is, the slab is separated from the casting roll in a state where the slab is not substantially loaded.

Therefore, the cast piece carried out from the casting roll 30
The thickness of 18 is not constant and changes. Therefore, next, the slab 18 is cooled to a temperature at which the strength and ductility start to appear.
Finally, a sound metal strip is obtained by rolling with a rolling roll 32 to a predetermined plate thickness. The cooling device 44 is equipped with several water sprays. The slab can be cooled by air cooling or water cooling without any particular limitation.

Among these series of steps, the rolling roll
In order to keep the rolling pressure at 32 constant, a non-contact type plate thickness measuring device 42 is inserted between the casting roll 30 and the rolling roll 32, and the cylinder is instructed by the control device 46 due to plate thickness fluctuation.
You may drive 50 and control the rolling-down force of the rolling roll 32.

FIG. 5 shows a modification of the case where the horizontal casting method is adopted. In the figure, a molten metal is injected from a tundish 64 into a casting roll 62 composed of a pair of rolls 60. , Slabs in the lateral direction in the same way as the single roll method
18 is released and reaches the rolling roll 66.

FIG. 6 shows a case where the casting roll 68 is composed of a single roll. The casting roll 68 and the rolling roll 70 are shown in FIG.
A guide 72 is provided between and. This guide 70
Since the slab strength is low between the casting roll and the rolling roll,
It is provided for transportation and may be in the form of a table or a roll.

As described above, according to the present invention, the casting roll and the casting method can be directed upward or sideways. Further, a single roll system or a twin roll system may be used. The casting roll and rolling roll may be driven by an ordinary hydraulic cylinder or screw system. Further, the number of rolling rolls is not limited to two, and may be multiple or tandem.

The plate thickness control with the rolling rolls can be performed by feedforward depending on the thickness of the slab before rolling and the opening of the casting roll as described above, or by feedback based on the thickness of the slab after rolling. Next, the operation and effect of the present invention will be described more specifically by way of examples.

[0027]

EXAMPLE In this example, a continuous casting test of an incoloy alloy was conducted using the apparatus shown in FIG. Casting roll has roll diameter
It consisted of a pair of rolls with a width of 300 mm and a width of 200 mm, and a rolling roll consisting of a cooling device and a roll diameter of 150 mm was placed behind the casting roll on the exit side.

When molten steel was poured from a ladle or a tundish into a casting roll rotating at 30 m / min to cast a slab with a plate thickness of 2 mm, the rolling load applied to the slab was set as close to zero as possible. Casting is performed while controlling the roll opening with a hydraulic cylinder so that the load of the load cell is 1 kg / mm ² or less. Therefore, the slab thickness obtained here is from 1.2 mm to 2.
It varies in the range of about 8 mm.

The cast piece carried out from the casting roll is sufficiently cooled until it falls below the recovery temperature of strength and ductility (drawing) shown in Fig. 3 depending on the steel type (for example, in Incoloy 800, -150 ° C from the solidification end temperature). After that, it is rolled to a predetermined plate thickness (for example, 1 mm) with a subsequent reduction roll. At this time, the thickness of the cast product discharged from the casting roll is measured or the roll opening is temporarily stored, and the rolling amount is controlled by the rolling roll to match the cast thickness and the roll opening. A thick metal ribbon is obtained.

The slab obtained by the above operation has no strength and ductility just below the freezing point, or has a low temperature range (
Since it is not subject to reduction in the embrittlement area), it is sound without defects such as surface cracks.

[0031]

As described above, according to the present invention, since the high temperature cracking susceptibility is high, even a material for which it is difficult to directly produce a healthy thin plate with only one pair of rolls can easily obtain a sound metal ribbon. Can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a conventional single roll type thin plate continuous casting apparatus.

FIG. 2 is a schematic explanatory view of a conventional twin roll type thin plate continuous casting apparatus.

FIG. 3 is a graph showing strength and drawing near the freezing point of some alloys.

FIG. 4 is a schematic explanatory view of a twin roll type thin plate continuous casting apparatus according to the present invention.

FIG. 5 is a schematic explanatory view of a modified example of a twin roll type thin plate continuous casting apparatus according to the present invention.

FIG. 6 is a schematic explanatory view of a single roll type thin plate continuous casting apparatus according to the present invention.

[Explanation of symbols]

 30: Casting roll 32: Rolling roll 34: Load cell 36: Hydraulic cylinder 40: Adjusting mechanism 42: Plate thickness measuring device 44: Cooling device

Claims (3)

[Claims] 1. A molten metal is poured into a casting roll composed of a single roll or twin rolls to form a solidified shell from the surface, and the resulting slab is not substantially loaded with a pressing force.
A thin plate, characterized in that a slab is separated from the casting roll, and then the slab is rolled down to a predetermined plate thickness by a rolling roll composed of one set or a plurality of pairs of rolls arranged in parallel. Continuous manufacturing method. 2. A casting roll composed of twin rolls,
The casting roll separated from the casting roll is rolled down to a predetermined plate thickness, and the rolling roll is provided with one or more pairs of a pair of rolls arranged in parallel. A continuous thin plate manufacturing apparatus equipped with a mechanism for adjusting the minimum gap of the casting roll so that the applied load becomes a certain value or less. 3. The continuous thin plate manufacturing apparatus according to claim 2, wherein a plate thickness measuring device and a cooling zone are provided between the casting roll and the rolling roll.