JPH0263649A - Strip continuous casting machine - Google Patents

Abstract

PURPOSE:To form deep pouring basin by joining a joining part of side dams and long wall side dams as slidable, constituting the side dam parts contacting with a circumferential parts of rolls with refractory having good cuttability and feeding out the side dam to casting direction. CONSTITUTION:One pair of the inner part cooling rolls 1a, 1b are set as facing and one pair of the side dams 3a, 3b are positioned on circumferential face of the rolls to a part or all of the thickness thereof. Then, the side dam is set at side part of both rolls 1a, 1b under opening at almost the equal interval as cast strip width. One pair of the long wall side dams 4a, 4b are set as facing to the roll axial direction on the circumferential surface of both rolls 1a, 1b to form the square-shaped pouring basin and molten metal in inner part is cast into the strip through gap between one pair of the rolls. The joining part of the side dam and the long wall side dam is made as slidable and the side dam parts contacting with the circumferential surface of the rolls are made to the refractory having good cuttability and the side dam is fed to the casting direction at the prescribed velocity and casting is executed while grinding and consuming the side dam surface with the roll surface. By this method, the cast strip having good quality can be stably obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a twin-roll continuous casting machine for continuously casting thin plates directly from molten metal (for example, molten steel).

[Background of the invention and prior art]

A pair of internal cooling rolls with horizontal axes that rotate in opposite directions are placed facing each other in parallel with an appropriate gap, and A so-called twin-roll continuous casting machine is known in which a pool is formed in the pool, and the molten metal in the pool is continuously cast into a thin plate through the gap while being cooled by the circumferential surface of a roll rotating once. There has also been a proposal to apply such a twin roll continuous casting machine to continuous casting of steel to directly produce thin steel plates from molten steel.

In order to continuously cast thin plate products from the gap between the roll pairs, a pool of molten metal is formed on the circumferential surface above the gap between the roll pairs, and the level of the molten metal is maintained substantially constant. It is necessary to continuously pour molten metal into this pool. In order to form this pool, the flow of hot water in the direction along the roll axis on the circumferential surface of the roll is restricted. A pair of dams with surfaces perpendicular to the roll axis are always required.

This dam usually also serves to regulate the width of the sheet slab. In this specification, this dam is referred to as a "side dam."

In addition to the side dams placed on the left and right sides, a pair of front and rear layers (herein referred to as long-side dams) having surfaces in the direction along the roll axis are placed on the circumferential surface of the pair of rolls at right angles to the side dams. It is also known that the side dam and this long side dam form a rectangular box-shaped pool of water. Forming such a box-shaped pool has the advantage that a sufficient volume for storing molten metal can be secured on the circumferential surface of the roll.

When such a box-shaped pool is fixed and installed on the circumferential surface of a pair of rolls, the moving end of the cast plate to be cast and the inner surface of the side dam will rub against each other on the side dam side. There is a problem of wear and tear in some parts.

In other words, the material of the side dam is a refractory with good insulation properties, which prevents the molten metal in contact with the side dam from solidifying on the surface of the side dam.In general, such insulation refractories have better resistance than solidified metal. It has poor abrasion resistance and is prone to scratches.

On the other hand, a part of the molten metal in the pool forms a thin solidified shell on each surface of each rotating roll, and as the rolls rotate, these thin shells grow and pass through the gap between the twin rolls. The solidified shell is reduced (rolled) near the roll gap where it is closest, and is formed into a thin plate of a predetermined thickness. Therefore, by crushing and rolling the solidified shell, the solidified shell tends to expand in the width direction near the roll gap. the result.

The ends of the cast plate will apply a large amount of pressure to the side dam. As a result, in a side dam made of a heat-insulating refractory as described above, it is inevitable that large friction will occur between the moving plate end and the fixed side dam. This can cause damage to the side dam refractories, cracks and shape defects at the ends due to unreasonable stress being applied to the ends of the plates, and even the formation of hot water in the sliding contact areas, making stable operations impossible. This is a big hindrance to doing so. therefore.

Conventionally, the general idea has been that it is best to use a refractory material with good wear resistance and as high strength as possible for the side dam.

In Japanese Patent Application No. 62-84555, the present inventors have developed a thin plate continuous casting method, which can be called the "grinding dam method" (or a method intermediate between a movable type and a fixed type), which fundamentally solves the problems associated with such side dams. He proposed the invention of a machine. This is contrary to the conventional idea of using high-strength refractories with good wear resistance for side dams, but instead we use refractories with good machinability, and this side dam with good machinability is cast. By actively feeding the material in the casting direction, the side dam is actively ground and worn out in the friction areas between the side dam, the roll surface, and the end of the plate to be cast. Since then, the present inventors have repeated casting tests using this grinding dam method.

[Purpose of the invention]

The present invention was made in Japanese Patent Application No. 1986-8
This is intended to further improve the grinding dam method proposed in No. 4555.

[Structure of the invention]

The twin-roll thin plate continuous casting machine of the present invention has a pair of internal cooling rolls that rotate in opposite directions and are arranged facing each other with their axes horizontal. A pair of rollers are disposed on the sides of the pair of rolls so as to be located on the surface and with an interval approximately corresponding to the width of the cast plate, and a pair of rollers are disposed on the circumferential surface of both rolls in the direction along the roll axis. A thin plate in which dams on the long sides are arranged facing each other, a rectangular pool is formed on the circumferential surface of the roll by the side dams and the dam on the long side, and the molten metal in this pool is continuously cast into a thin plate through the gap between the pair of rolls. This is a continuous casting machine, in which the joint between the side dam and the long side dam is slidably joined, and the side dam portion, which will come into contact with the circumferential surface of the roll during casting, is made of a material with good machinability. It is characterized in that it is made of a refractory material, is provided with a mechanism for feeding out the side dam in the casting direction at a predetermined speed, and is cast while the side dam portion in contact with the roll surface is ground and consumed by the roll surface by this feeding mechanism. At this time, the circumferential surface of the roll that will come into contact with the side dam is formed into a rough surface capable of grinding. This rough surface is preferably formed by a plating layer or a sprayed layer of hard metal, or a sprayed layer of ceramics or cermet, and the circumferential surface of the roll that will come into contact with the molten metal is also thermally insulated by forming a sprayed layer as described above. If the dam is formed in a layer, the molten metal is prevented from solidifying on the lower inner surface of the long side dam (near the area in contact with the circumferential surface of the roll).

That is, the present invention is an attempt to apply the side dam grinding method proposed in Japanese Patent Application No. 1984-84555 to a twin roll type continuous casting machine that forms a deep pool with a side dam and a long side dam. Since molten metal is stored at a sufficient depth above the circumferential surface of the roll, high-quality casting plates can be cast more stably.

〔Example〕

The content of the present invention will be specifically explained below according to an embodiment shown in one drawing.

In FIG. 1, reference numerals 1a and lb refer to a pair of internal cooling rolls that are arranged opposite to each other with their axes horizontal so as to rotate in opposite directions (the directions of rotation of both are indicated by arrows), and 2 refers to these rolls la and lb. 3a and 3b are side dams, 4a and 4b are molten metal in a pool formed on the circumferential surface R of
5a and 5b are side dam cases, and 6 is a thin plate to be cast.

Roll pair 1a, lb are internally cooled rolls. In the illustrated examples, water-cooled rolls are used. More specifically, both roll pairs la and lb have their circumferential surfaces R
A groove-shaped cooling water passage is formed inside the roll sleeve (not shown in the figure), and by passing water through this cooling water passage, the circumferential surface R is brought to a predetermined temperature. It is supposed to be cooled. Supply of cooling water to the cooling water passage inside this circumferential surface R and drainage thereof are performed from the roll shaft. For this reason, the roll shaft is constructed in the shape of a double pipe, with the inner pipe serving as the cooling water supply pipe and the annular pipe formed between the outer pipe and the inner pipe serving as the drain pipe. This can be continued even while the device is in operation.

The side dams 3a, 3b are held by metal side dam cases 5a, 5b attached to their outer surfaces, and the side dams 3a are moved during casting in the casting direction as described later. ,3
b is sent out in the casting direction. The side dams 3a, 3b themselves are made of a refractory material with good machinability, and an example of their shape is shown in FIG. In FIG. 2, only one side 3b of the side dams 3a and 3b is shown, but the other side 3a has a similar shape.

As seen in the figure, of the total thickness W, the thickness of the inner part -1 is the thickness of the part installed on the roll circumferential surface R, and the thickness of the other outer part -2 is the thickness of the part installed on the roll circumferential surface R. This is the thickness of the installation part that is outside the roll circumferential surface.

That is, for the inner thickness 111 portion, roll 1a,
Bottom surface 11.11 with a curved surface corresponding to the circumferential shape of 1b
', and for the outer thickness 12 parts, roll Ia,
It has a shape in which a portion 12.12'' that makes sliding contact with the side surface (indicated by S in FIG. 1) of lb extends below the bottom surface 11.11'.

As the material for the side dams 3a and 3b, a refractory is suitable since it must have good heat insulation properties, but in the case of the present invention, it must also have good machinability. It is necessary that the bottom surface ILII' is ground by the rough surface of the roll circumferential surface (indicated by 10 in Figure 1), and the material is also such that it can be easily ground at the edges of the plate to be cast. This is because it is preferable. Suitable materials include insulating bricks with good machinability, ceramic fiberboard,
Poron nitride (BN) etc. In the illustrated example, thickness 1 and thickness 2 are all made of refractory material with good machinability.

Unlike the side dams, the long side dams 4a and 4b are made of high-strength heat-insulating refractories, and are arranged in the direction along the roll axis (side dam 3a) so that their bottoms are in sliding contact with the roll circumferential surface.
, 3b) and fixed at that position. At this time, the side dams 3a and 3b are joined at their joints so that they can slide in the casting direction. In the illustrated example, protruding keys extending in the casting direction (vertical direction) are formed on both sides of the long side dams 4a, 4b, and key grooves (second
14a and 14b in the figure) are drilled in the casting direction (vertical direction), and the side dam 3 is formed by this key and keyway.
This shows an example in which dams a and 3b are joined to fixed long-side dams 4a and 4b so as to be able to freely slide in the casting direction.

Next, a mechanism for sending out the side dams 3a and 3b will be explained. In the example shown in Fig. 1, the side dam 3a of the machinable refractory
, 3b, a metal side dam case 5. +, 5
Attach the side dams 3a and 3b so that the bottom surfaces 11 and 11' of the 1-thickness portion described in FIG. , and the inner surface of the thickness is 1212°.
The side dams 3a, 3b are set so that they are in sliding contact with the side surfaces S of the rolls la, lb, and the long side dams 4a, 4b
are set so as to be able to slide on the side dams 3a and 3b as described above. and 2 side dam case 5a,
The side dam cases 5a and 5b are moved in the casting direction by supporting the threaded column 8 via a nut 9 fixed to the case side and rotating the column 8 around the axis. As a result, while the device is in operation, the bottom surface 11.11' of the side dam 3a3b is ground by the roll circumferential surface R that rotates once, and the side dam 3a3b descends while being consumed. At this time, the long side dams 4a, 4b are connected to the side dams 3a, 3b by a key and a keyway in a slider-pull manner in the casting direction, so the downward movement of the side dams 3a, 3b does not affect the long side dams 4a, 4b. Not communicated effectively.

In addition to mechanically interlocking the side dam cases 5a, 5b and the side dams 3a, 3b, they may be bonded together using a bonding agent at the bonding interface between the two, thereby providing a coating with low tensile strength for boat fishing. Reinforcement of machinability and large objects is done. As for the mechanism for lowering the side dam cases 5a and 5b, it is preferable to use a method of continuously lowering the side dam cases 5a and 5b during operation of the device, but depending on the case, an intermittent movement method of repeating lowering and stopping may be used, or a method of lowering the side dam cases 5a and 5b while slightly vibrating them may be used. It may be a method. In any case, it is preferable to control the lowering speed using the lowering amount of the side dam or the width of the plate to be cast as a detection signal.

On the other hand, of the circumferential surface R of the roll, the bottom surface 1 of the side dam
The part that comes into sliding contact with 1.11' is formed into a rough surface with grinding ability. This rough surface portion is indicated by 10 in FIG. If the roughness and hardness of this portion 10 are appropriate depending on the material and casting conditions of the side dam, the bottom surface 11.1 of the side dam
1' is well ground during casting. This portion 10 is preferably a plated or sprayed layer of hard metal, or a sprayed layer of ceramic or cermet. On the other hand, it is preferable that the surface of the roll sleeve, which comes into contact with the molten metal and therefore comes into sliding contact with the bottom surfaces of the long side dams 4a and 4b, also has sufficient hardness and appropriate heat insulation properties. Providing appropriate heat insulation properties can prevent the formation of solidified shells on the lower inner surfaces of the long side dams 4a, 4b (inner surfaces in the vicinity of sliding contact with the roll circumferential surface). For this reason, it is preferable to form a sprayed ceramic or cermet layer on the surface of the roll sleeve as well. If the rough surface portion 10 and the rest of the roll sleeve surface are made of the same hard and heat insulating material layer, only the rough surface portion 10 may have a particularly large roughness degree, but the entire surface may have a moderate roughness. It can also be formed. Thermal spraying or plating metals include Ni, Ni-Fe alloy, Ni-Cr alloy, carbon steel and stainless steel, and the thermal spraying ceramics include Crz.
flLTiO□, ^J2203+ZrO□, etc., and as thermal sprayed cermets, Zr02-NiCr, Cr5
C2-NiCr, WC-Co, etc. are preferred. In the case of thermal spraying, it is possible to form a naturally uneven surface by depositing thermal spray particles, and it is possible to obtain a rough surface that allows good grinding and wear of the machinable side dam.

Note that 16 in FIG. 1 indicates a brush for cleaning the rough surface portion 10, and if this brush 16 is placed so as to come into contact with the portion 10, the portion 10 will be cleaned by the rotation of the rolls Ia and lb. It is possible to remove grinding powder adhering to the rough surface, and it is possible to prevent a decrease in grinding performance due to clogging of the rough surface.

FIG. 3 shows the inner surface state of the side dam according to the present invention at the initial stage of casting. On the inner surface of the side dam, the side edges of the solidified shells formed on the surfaces of both internal cooling rolls come into contact at points a and a' in the drawing and merge at point A. In other words, a portion of the molten metal in the pool is cooled on the surface of each roll and solidified into a thin shell, and as the rolls rotate, the two solidified shells grow and merge, and are rolled to a predetermined thickness between the roll gaps. However, the ends of the solidified shell formed on the roll surface come into contact with the inner surface of the side dam at levels a and a'. The initial shape of the side dam (before being ground during operation of the machine) is adjusted so that the position of the confluence A of this solidified shell is approximately the same as the lower edge 13 within the roll width of the side dam (inside 1 in Figure 2). However, during casting, one confluence point A may come to a position above the position of the lower edge 13 due to variations in casting conditions. In this case, due to the expansion in the width direction of the plate (the solidified metal plate after passing through the confluence point A) caused by rolling with the rolls,
The refractory material in this area will be scraped off. If the side dam is not lowered in this state, the width of the board will continue to gradually expand, and if it exceeds the roll width, the end of the board will have a dog-bone shape and swell. If the condition progresses further, the side dam will be damaged and a breakout will occur. In the present invention, the side dam is lowered at a predetermined speed, so even if this part is scraped off by the plate edge, new surfaces will descend one after another, so this situation will not occur and the plate will always be cast with a predetermined width. It will be possible.

Figure 4 shows the inner surface of the side dam when casting has progressed and the side dam has descended considerably. The bottom surface 11.11 and the lower edge 13 are scraped off by the rough surface 1o of the roll and the side edge of the casting plate, respectively, and their positions are moved relatively upward compared to their initial positions in FIG. At the same time, the lower edge 13 is cut slightly diagonally by the edge of the plate. Then, the inner surface 15 of the refractory material in a portion protruding from the width of the roll is exposed at the lower part of the lower edge 13, and this portion also serves to prevent leakage in the unlikely event of leakage.

However, in this way, the bottom surface 11.11' and the lower edge 13
Even if the solidified shell is scraped off, the side edge of the solidified shell remains at a in the drawing.
, there is no change in the fact that they meet at the level indicated by a' and merge at point A.

In addition, in two or more embodiments, part of the thickness is within the roll width,
Although a side dam having a thickness outside the roll width has been described as an example, a system in which the side dam is installed so that the entire thickness is within the roll width is also applicable. In addition, as the side dam delivery mechanism, the cylinder piston system, rack and pinion system, etc. as described above can be applied.

[Effect]

As described above, the present invention was first made by the present inventors in Japanese Patent Application No. 1983-
The "grinding dam method" proposed in No. 84555 has been realized even in the case of forming a deep puddle on the roll circumferential surface in combination with a long side dam, and the advantages of the grinding dam method can be achieved. Since it is possible to form a deep pool while enjoying the water as it is, it is possible to stably produce high-quality thin plates.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the main parts of an embodiment of the apparatus according to the present invention, FIG. 2 is a perspective view showing an example of the shape of the refractory of the side dam in the apparatus shown in FIG. 1, and FIG. Fig. 4 is a perspective view of the side dam in the apparatus shown in Fig. 1, showing a state in which the degree of grinding is small in the initial stage of casting; Fig. 4 is a perspective view of the side dam in the apparatus shown in Fig. 1, showing a state in which the degree of grinding has progressed during the casting process. It is a figure showing a state. Ia, lb... Pair of internal cooling rolls, 2... Pool 3a, 3b... Side dam, 4a, 4b... Long side dam 6... Cast plate, 8... Threaded support. 10... Portion of the roll circumferential surface that slides into contact with the bottom surface of the side dam (rough surface), 11.11''... The bottom surface of the side dam having a curved surface corresponding to the circumferential shape of the roll.

Claims (4)

[Claims] (1) A pair of internal cooling rolls that rotate in opposite directions are arranged facing each other with their axes horizontal, and a pair of side dams are placed so that part or all of their thickness is located on the circumferential surface of the rolls, and then cast. A pair of long side dams are disposed on the side portions of the pair of rolls with an interval approximately corresponding to the width of the plate, and a pair of long side dams are disposed facing each other in the direction along the roll axis on the circumferential surfaces of both rolls. In a thin plate continuous casting machine that forms a rectangular box-shaped pool on the circumferential surface of the roll by a side dam and a long side dam, and continuously casts the molten metal in this pool into a thin plate through the gap between the roll pairs, this side dam and The joint part with the long side dam is slidably joined, and at least the side dam part that will come into contact with the circumferential surface of the roll during casting is made of a refractory material with good machinability, and the side dam is cast. A thin plate continuous casting machine that is equipped with a mechanism that feeds out at a predetermined speed in a direction, and uses this feeding mechanism to grind and wear out the side dam portion that contacts the roll surface while casting. (2) The thin plate continuous casting machine according to claim 1, wherein the circumferential surface of the roll that comes into contact with the side dam is formed into a rough surface having a grinding ability. (3) The thin plate continuous casting machine according to claim 1 or 2, wherein a surface layer with good heat insulation properties is formed on the circumferential surface of the roll that comes into contact with the molten metal in the sump. (4) The thin plate continuous casting machine according to claim 1, 2 or 3, wherein the rough surface having grinding ability and the surface layer having good heat insulation properties are formed of a thermally sprayed layer of hard metal, ceramics or cermet.