JPS6264457A - Continuous casting device for thin sheet of steel - Google Patents

Abstract

PURPOSE:To prevent the leakage of steel and the wear of side dams which form a pouring basin on the circumferential surface of a roll pair by bringing the bottom edges of said side dams upper than the narrowest position of the roll pair and pressing the end of a soft metal bar to the space right thereunder. CONSTITUTION:The pouring basin 3 is formed by the side dams 2a, 2b on the circumferential surface R of a pair of parallel disposed internally cooled rolls 1a, 1b which rotate in the directions opposite from each other. The molten steel therein is continuously cast through the spacing between the rolls 1a and 1b to a thin ingot 4. The bottom edges 6 of both side dams 2a, 2b of the twin roll type continuous casting machine constituted in the above-mentioned manner are brought upper than the narrowest position of the rolls 1a, 1b. The end of the soft metal bar 5 is pressed to the space right under the edges 6. The bar 5 is adequately made of Pb, Al, Sn, Zn or alloy essentially consisting of these metals and is preferably continuously supplied at a specified extrusion speed horizontally in an arrow direction during casting.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of a twin-roll continuous caster for continuous casting of thin plates directly from molten steel.

[Conventional technology]

A pair of internal cooling rolls that rotate in opposite directions are arranged parallel to each other with an appropriate gap between them, and a pool is formed on the circumferential surface of the rolls above the gap.

A so-called twin-roll continuous casting machine is known, which continuously casts the molten metal in the pool into a thin plate through the gap while cooling the molten metal on the circumferential surface of the roll rotating once. This kind of twin-roll continuous casting machine is applied to continuous casting of steel.

Proposals have also been made to directly produce thin steel sheets from molten steel.

In order to continuously cast thin plate products from the gap between the roll pairs, it is necessary to form a pool of molten steel above the gap between the roll pairs and continuously pour molten steel into this pool. To form a hot water puddle.

First, a dam is required on the circumferential surface of the roll to restrict the flow of hot water in the width direction of the thin plate to be cast.

This dam usually plays the role of regulating the width of the slab,
Therefore, to control both edges of the slab.

It consists of two paired fixed walls. The two fixed walls that restrict the flow of hot water in the width direction of the slab are referred to herein as "side dams." In addition, in order to form a large-capacity pool on the circumferential surface of the rolls, it is necessary to increase the height of this side dam and also to erect a fixed wall on the circumferential surface of the pair of rolls in the direction along the roll axis. is also required. This fixed wall along the roll axis is called the "long side dam". In this case, a rectangular container is formed by the side dam and the long side dam, and the circumferential surface of the pair of rolls becomes the bottom surface.

However, when using rolls with a large diameter.

Even if the long-side dam is not provided, the roll circumferential surface itself plays the role of this wall, and it is also possible to form a water reservoir with only the side dam.

In any case, if a site dam is not provided, the hot water will be injected onto the roll circumferential surface (in the roll axis direction (in the width direction of the slab))
Therefore, it is difficult to continuously cast plates with a constant slab width.

As for the installation method of this pair of side dams.

There are cases where the pair is accommodated within the roll width (the length of the roll circumferential surface along the roll axis), and cases where the pair is placed within the roll width. In the former case, the 3-car side dam will be installed on the circumferential surface of the roll, and in the latter case, the 1-car side dam will be installed on the outside of both sides of the roll along the roll side surface. This is normal.

[Problem that the invention seeks to solve]

This is because the side dam as described above restricts the flow of hot water in the width direction on the circumferential surface of the roll.

If the lower end of this side dam is not lowered to a position where the hot water on the circumferential surface of the roll is at least solidified, hot water will leak from below this side dam. In this case, since it is inevitable that the actual solidification completion position varies to some extent during casting, the lower end of the side dam must be located below the range of variation of the solidification completion position. More specifically, steel leakage cannot be completely prevented unless the lower end of the side dam is lowered to or below the narrowest gap position between the roll pair.

However, near the position of the narrowest gap between the roll pairs, a
Since the hard shell is rolled by rolls and extruded in the width direction, if there is a wall of a side dam in this area, a force is applied from the inside of this side dam to the outside, and both ends of the slab apply pressure to the inside of this side dam. However, he was sent away. This resulted in severe wear on the inner surface of the side dam. or break, causing steel leakage.

In particular, when a side dam is installed in contact with the roll side surface, a gap is generated between the roll side surface and the side dam, and steel leakage is likely to occur from there.

Furthermore, if the solidified shell is pushed out while applying a strong frictional force to the side dam, this frictional force may cause cracks at both ends of the slab, or in some cases cause temporary breakage.

On the other hand, in order to avoid this, if the lower end of the side dam is located above the range of variation of the solidification completion position, steel leakage will occur from the lower end of the side dam when the solidification completion position a is lowered.

Japanese Unexamined Patent Publication No. 59-215255 discloses a control method in which a side dam is installed by being pressed against a roll side surface, and the side dam is raised and lowered by detecting the amount of opening between the five side dams and the roll side surface. Although this method can solve the above problems to some extent,
It is unavoidable that the side dam is pushed outward by the rolling of the solidified shell or is subjected to friction by the solidified shell.

Therefore, it is thought that the problems of steel leakage between the side dam and the roll side surface, wear of the side dam, and plate breakage will remain to some extent. In addition, considerably high sensitivity and quick responsiveness will be required for the control.

The present invention aims to solve the problems in such a twin-roll continuous casting apparatus.

Means for Solving Problem C] In order to solve the above-mentioned problems, the present invention provides a method in which a pair of internal cooling rolls rotating in opposite directions are disposed in parallel and facing each other, and the circumferential surface of the pair of rolls is In a twin-roll continuous casting machine that continuously casts the molten metal in the puddle formed above into a thin plate through the gap between the roll pairs, a side dam is provided on the circumferential surface of the roll pair, or a side dam is provided on the circumferential surface of the roll pair, or A pool of water is formed on the circumferential surface by providing a side dam in contact with the side dam, and the lower edges of both side dams are positioned above the narrowest position of the pair of rolls. This is an apparatus for continuous casting of thin steel sheets, which is characterized by the fact that the end of a soft metal bar is pressed against the steel plate.

In the apparatus of the present invention, the lower edge position of the side dam is located above the position of the narrowest gap between the pair of rolls.

More preferably, the lower edge of the side dam is located above the normal solidification completion position, so that when the hard shell is rolled in the narrowest gap between the pair of rolls, both ends of the side dam
Allow it to extend freely without being damaged.

Then, by continuously supplying the soft metal bar in a substantially horizontal direction to both side gaps near the narrowest gap position of the roll pair (the gap directly below the lower edge of the side dam), the ends of the soft metal bar are Along with V-ru to play the role of a side dam in the space directly below the lower edge.

By composing this solid bar with a material with low cutting resistance, even if the end of the plate to be cast is sent out while being in contact with one end of this bar, it is easily scraped off, thereby reducing the friction between them. In this way, the above-mentioned problems are solved.

Therefore, the soft metal bar used in the device of the present invention should firstly function as a side dam that can prevent steel leakage even if it comes into contact with molten steel, and secondly, it should not restrict the passage of the end of the plate to be cast. ,is important. For this purpose, this soft metal bar? 8. Must not react violently with steel or contaminate molten steel, must have sufficient strength (shape retention ability) to hold back molten steel, and must be free-cutting so that it can be easily scraped off by the end of the slab to be cast. It is necessary to meet certain conditions such as having a sexual orientation. As a soft metal, pb, ^' + -) n + Z n +
Alternatively, alloys based on these metals are suitable. These metals are not only soft and easily scraped by the edge of the plate, but also have a low melting point, so they are melted appropriately and smooth and fluidize the tip of the shaved bar, so the friction with the edge of the plate is extremely small. Become something. Furthermore, since it is a metal, it has good thermal conductivity and its cooling ability solidifies the molten steel that is about to leak from the gaps 1 and 11, thereby preventing steel leakage. This bar may be a single piece of soft metal, but it is powder of soft metal.

It may also be one small piece solidified with a suitable binder.

The contents of the apparatus of the present invention will be specifically explained below according to the embodiments shown in the drawings.

〔Example〕

FIG. 1 is a perspective view of essential parts showing an embodiment of the apparatus of the present invention, and shows a pair of internal cooling rolls rotating in opposite directions.
a and 1b are arranged facing each other in parallel, and this pair of rolls 1a and i
In a twin-roll continuous casting machine that continuously casts molten metal in a puddle formed on the circumferential surface R of the roll pair 1a and 1b into a thin plate 4 through the gap between the roll pairs 1a and 1b, the circumferential surface of the roll pairs 1a and 1b is R
A pool 3 is formed by raising the side dams 2a, 2b on top of the side dams 2a, 2b, and the lower edges of the side dams 2a, 2b are positioned above the narrowest position of the roll pair 1a, 1b. , 2b and the end circumferential surfaces of the roll pairs 1a, 1b, the soft metal bars 5 are continuously supplied to both the gaps near the narrowest positions of the roll pairs 1a, 1b. Continuous casting equipment is shown.

The roll pair 1a, Ib is an internal cooling roll that rotates in opposite directions by eight rotating shafts 7a, 7b. A cooling water passage (not shown) is provided on the back side of the circumferential surface R of each roll pair 1a, 1b. It is designed to allow drainage. That is, the rotating shafts 7a and 7b are configured as double pipes, one of which is configured as an outgoing pipe (water supply pipe), and the other pipe line 9a, 9b is a return pipe (drainage pipe).

In the embodiment shown in FIG. 1, the side dams 2a, 2b stand on the circumferential surface R at both ends of the roll pair 1a, 1b, and the roll pair 1a, 1b sandwiched between the side dams 2a, 2b. A hot water pool 3 is formed on the surface R of the circle 14. Therefore, the width of the slab to be cast is.

This corresponds to the distance between the inner walls of the side walls 1, 2a, and 2b within the range of the axial length of the roll pair 1a, 1b. Both side dams 2a, 2b may be supported from the sides or from the top. In the device of the present invention, the lower edges G of both side dams 2a, 2b are located at the narrowest gap between the roll pairs 1a, 1b (roll pairs 1a, ib
The position on the line connecting the axes of , this is called the narrowest position). More specifically, the position of the lower edge 6 is such that it is located above the position where solidification of the molten steel is completed in the steady state π during the casting operation.

At t7, the end of the soft metal bar 5 is pressed against the space directly below the lower edge 6. This soft metal bar 5 is made of a solid material that satisfies the above-mentioned conditions, and as shown in Figure 1, the soft metal bar 5 has a lower edge 6 of the side dams 2a, 21+ and a pair of rolls 1a.
, 1b is formed into a bar having a cross section approximately equal to the substantially fan-shaped cross section surrounded by the end circumferential surface R of the ends. In FIG. 1, only the soft metal bar 5 on the side dam 2a is visible, but a similar soft metal bar 5 is also pressed directly under the edge of the side dam 2b on the opposite side. The lower edges 6 of the side dams 2a, 2b and the upper surface of the soft metal bar 5 are in contact with each other, and therefore the water pool 3 is
, 2b, the end face of the soft metal bar 5, and the roll pair 1
C is formed by the circumferential surface R of a and Lb.

This relationship is diagrammatically shown in FIGS. 2 and 3.

FIG. 2 is a partially enlarged view of the vicinity of the narrowest position when looking at one side of the side surface S of the roll pair 1a, 1b. Roll vs! a,
The narrowest gap 2 is formed between the pair of rolls on the line Q connecting the axes of 1b, and the side dam 2 is installed so that the lower edge 6 of the side dam 2 is above this narrowest position. Ru. More specifically, in a steady state of operation, a side dam is placed above the position 11 where the solidified shells 10a, 10b that solidify and develop on the circumferential surfaces of the roll pair 1a, 1'o complete solidification. , position the lower edge 6 of a + 2 h. By positioning the lower part 1i6 of the side dams 2a, 2b upward in this way, a substantially fan-shaped cross section surrounded by the lower edge 6 and the end circumferential surfaces of the roll pairs Ia, 1b is provided directly below the lower edge 6. Each time a gap is formed, the end of the soft metal bar 5 having a cross-sectional shape corresponding to the plane of the gap is inserted into the gap in a substantially horizontal direction from the side.

Molten steel remains above this solidification completion position 11, and the thickness of the solidification shell at the solidification completion position 11 is usually larger than the narrowest gap between the roll pair 1a, Ib. Therefore, in the installation method of the side dams 2a, 2b according to the present invention, the side dams 2a, 2b alone cannot prevent steel leakage, but the end face of the soft metal bar 5 functions as a side dam to prevent this. Become. The solidified shell is rolled in the narrowest gap between the roll pair 1a, Ib, and even if it overhangs in the width direction G, the side dam 2a
, 2b do not exist at this position, so applying pressure to the inside thereof is prevented.7 This amount of overhang is absorbed by the soft metal bar 5.

Continuous supply of the soft metal bar 5 is achieved by winding the bar onto a reel, for example, as a wire with a predetermined cross-sectional shape, and continuously feeding it out at a predetermined speed with a pinch roller.

The position of the end face in the cavity of the soft metal bar 5 at the initial stage of casting is preferably centered so that it is within the thickness range of the side dams 2a, 2b. Then, casting is started, and the feed rate is controlled so that the end face is always fed within the width of the lower edge 6, and the end face is fed out by a conveying device in proportion to the amount that the end face is consumed.

Figure 3 is +? To form the JjI reservoir 3, long side dams 17a, ], 7b are also raised on the circumferential surface R along the axial direction of the roll pair l''+1b, and the long side dams 17
This figure shows an apparatus according to the present invention having substantially the same structure as the apparatus shown in FIG. 1, except that side dams 2a and 2b, which stand up at both ends of the circumferential surface R, form a rectangular container. In the case of this device, compared to the device of FIG.
, 1b have the same diameter, a pool with a large capacity can be formed, and if the /a pool has the same capacity, the roll pair 1a, I
The diameter of b can be made small.

In Fig. 4, the side dams 2a and 2b are connected to the roll pair 1a,
Except that it was fixed in contact with the side surface S of 1b so that the gap between the pair of rolls 1a and 1b was sandwiched over the full width of the rolls.

1 shows an apparatus of the invention which is substantially a superseding arrangement of the apparatus of FIG. 1; In this case, the width of the roll pairs 1a, 1bO in the axial direction substantially corresponds to the width of the slab 4. In this example, below the lower edge 6 of the Zyde dams 2a, 2b are the roll pairs 1a, 1.
! Although the + circumferential surface R does not exist, the cross-sectional shape of the soft metal bar 5 may be a shape surrounded by the lower edge 6 and a surface extending the circumferential surface R in the roll width direction, or a slightly similar shape to the - side. It may have a large shape.

[Example of actual machine operation]

An example in which continuous thin plate casting of molten steel was carried out using the apparatus shown in FIG. 1 will be briefly described below.

The roll pair 1a, 1b is made of 340C and has a diameter of 3.
A pair of internal water-cooled rolls measuring 00mm x width 200I+III+ was used. The narrowest gap between the roll pair 1a, 1b was set to 3 mm, and the silica side dams 2a, 2b were placed at their lower edges 6.
was set so that it was 30 mm above the narrowest position. As the soft metal bar 5, Pb was used. This bar was pushed out with an air cylinder at a speed of 2 mm/see into the void immediately below the lower edge 6 of the side dams 2a, 2b.

The molten steel of 5US304 was stored in the hot water reservoir 3 at 1000℃.

The rotation speed of the pair of rolls 1a and 1b was set to 7 rpm, and a thin plate slab was continuously cast from the narrowest gap, and 3 mm thick x 1
A strip with a width of 80 m and a length of 30 m was manufactured. There was no steel leakage during operation, and no plate breakage occurred. In addition, we observed the inside of Ido Dams 2a and 2b, which were constructed after Slt construction, but found no wear or damage to the shells.

[Effect]

In a twin-roll continuous casting device, as conceptually shown in Fig. 2, molten steel in the pool is passed through internal cooling rolls la and i.
Heat is removed at the part that contacts b, and this roll pair 1a, 1b
Solidified shell 10a on the circumferential surface of.

10b grows thicker as it approaches the narrowest gap position. In the apparatus of the present invention, the lower edges 6 of the side dams 2a, 2b are arranged above the position of the narrowest gap between the roll pairs 1a, 1b.
It is possible to select operating conditions such that the position is between the lower edge 6 of b and the narrowest gap and position of the coal pairs 1a and 1b.
The thickness of the coagulated and solidified shell at the solidification completion point II is the thickness of the roll pair 1a
, 1b is larger than the narrowest gap, and when passing through this narrowest gap, the shell is pressed down and pushed out in the width direction of the plate, but in the device of the present invention, only the soft metal bar 5 is present in this part, The extruded opposite end does not cause friction with the side dams 2a, 2b, and the molten steel is dammed up by the end face of the soft metal bar 5. Therefore, the aforementioned problems can be effectively solved.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing essential parts of an embodiment of the apparatus according to the present invention, FIG. 2 is a partially enlarged view of the apparatus shown in FIG. 1 seen from the roll side surface, and FIG. FIG. 4 is a perspective view showing the main parts of yet another embodiment of the apparatus according to the present invention. 1a, 1b--roll pair, 2a, 2b--'noid dam. 3. Hot water pool, 4. Thin plate slab, 5. Soft metal bar, 6. Lower edge of side dam, 10. Solidified shell.

Claims (3)

[Claims] (1) A pair of internal cooling rolls 1a and 1b that rotate in opposite directions are disposed in parallel to each other, and this pair of rolls 1a and 1
In a twin-roll continuous casting machine that continuously casts molten metal in a puddle formed on the circumferential surface R of b into a thin plate through the gap between the pair of rolls 1a and 1b, the circumferential surface of the pair of rolls 1a and 1b Side dam 2a on top of R
, 2b or by providing side dams 2a, 2b in contact with both side surfaces S of the pair of rolls 1a, 1b, a pool 3 is formed on the circumferential surface R, and the lower edges of both side dams 2a, 2b are formed. 6 is located above the narrowest position of the roll pair 1a, 1b, and the end of the soft metal bar 5 is pressed against the space directly under the lower edge 6 of both side dams 2a, 2b. Continuous casting equipment for steel thin plates. (2) The soft metal bar 5 is made of Pb, Al, Sn, and Zn.
2. The continuous steel thin plate casting apparatus according to claim 1, which is constructed of a material consisting of , or an alloy based on these metals. (3) The soft metal bar 5 is continuously supplied at a constant extrusion speed during casting.
A continuous thin plate casting apparatus for steel as described in Section 1.