JPH08267189A - Twin roll type strip continuous casting machine - Google Patents

Abstract

PURPOSE: To provide a twin roll type strip continuous casting machine, in which the hitting of the molten metal stream is not given directly to a short side weir by inserting a simple shaped and inexpensive dam into the space in mold rolls and restraining the molten metal stream from a nozzle for supplying the molten metal with the dam. CONSTITUTION: The molten metal stream supplied toward the short side weir 7 side from the nozzle 4 for supplying the molten metal is hit against the surface of the dam 10 and suppressed (reduced) to reach the short side weir 7 side as the slow stream and therefore, the bulging at the short side weir 7 is not caused and the uniform dynamic pressure is given on the short side weir 7. By this constitution, a sector type special and expensive nozzle is not used but only the simple shaped dam 10 is inserted into the space 3 in the mold rolls 1, 2, and thereby, the molten metal stream to the direction of the short side weir 7 from the nozzle 4 for supplying the molten metal can be suppressed by the dam 10. The hitting of the molten metal stream can not be given directly to the short side weir 7 and the trouble caused by the stream in the side direction of the molten metal 5 can be eliminated in the low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a thin steel plate having a thickness of 2 mm to 6 mm directly cast from a molten metal and subjected to direct cold rolling without a hot rolling process to form a thin steel plate having a thickness of about 0.3 mm to 0.5 mm. The present invention relates to a twin-roll type thin plate continuous casting machine used for manufacturing.

[0002]

2. Description of the Related Art For example, a thin steel plate having a thickness of about 0.3 mm to 0.5 mm is usually processed by a slab continuous casting machine from a slab material having a thickness of 100 mm to 150 mm through hot rolling and cold rolling. Manufactured. According to this method, not only the number of steps is large, but also the once cooled slab material needs to be heated again for hot rolling. for that reason,
A twin roll type thin plate continuous casting machine, which directly casts steel plates from the molten metal, is used.

In a conventional twin roll type thin plate continuous casting machine, as shown in FIG. 9, for example, a straight type single melt supply nozzle 20 is used, and a supply port 21 of this melt supply nozzle 20 is used.
Is opposed to the short side weir 22. In this case, when the short-side weir 22 made of refractory or ceramics is used, the short-side weir 22 is preheated before the start of casting in order to prevent the solidified layer from growing on the short-side weir 22 during casting. It is necessary, and hopefully, to heat using a heating device during casting, or to utilize the heat of the supplied molten metal, the molten metal flow 23 is shortened by the short side weir 22,
In particular, it was effective to place the short side weir 22 and the mold roll in the vicinity of sliding.

Further, as shown in FIG. 10, when an electromagnetic force utilizing short side weir 25 utilizing electromagnetic force is used for the short side weir, it is counteracted by the electromagnetic force against the molten metal flow 23 from the molten metal supply nozzle 20. Due to the generated force 26, the molten metal can be held in balance with the molten metal static pressure and the dynamic pressure due to the flow. Further, when using the electromagnetic side short side weir 25, it is not necessary to heat the electromagnetic side short side weir 25 by applying the molten metal flow 23 to the electromagnetic side short side weir 25 side. Providing dynamic pressure requires electromagnetic force above static pressure.

[0005]

In the short side weir 22 of refractory or ceramics shown in FIG. 9, the molten metal flow 23 is directed to the short side weir 22 side, so that the short side weir 22 is effectively heated. However, the molten metal flow 23 hitting the short side weir 22 is
A rising flow 23A along the line 22 was generated, which was one of the causes of the surface defects of the slab. Further, the molten metal flow 23 sometimes causes turbulence, and when the turbulence appears on the surface of the molten metal, and when it occurs at the winding part of the boundary between the mold roll and the molten metal, the metal oxide film that tends to float on the surface of the molten metal is also involved. It is one of the causes of surface defects of the slab.

When the short side weir 25 utilizing electromagnetic force is used for the short side weir shown in FIG. 10, the sum of the pressure by the molten metal flow 23 from the molten metal supply nozzle 20 and the static pressure of the molten metal is the electromagnetic force. If there is fishing, there is no swelling or disorder on the surface of the molten metal, and there is no swelling of the molten metal on the surface of the short side weir 25 using electromagnetic force, but there is a margin for electromagnetic force for stable operation, Also, the flow of molten metal from the molten metal supply nozzle 20
Since 23 is not always constant, the short-side weir using electromagnetic force 25
A bulge 23B is generated at a portion where the molten metal flow 23 collides with the molten metal flow generated by an electromagnetic force in a region slightly away from

In reality, it is difficult to keep the molten metal flow 23 from the molten metal supply nozzle 20 constant, and it is impossible to keep the dynamic pressure constant. Therefore, in the twin roll type thin plate continuous casting machine in which the electromagnetic force utilization short side weir 25 is arranged, when the molten steel supply nozzle 20 with the supply port 21 oriented toward the electromagnetic force utilization short side weir 25 is used, Not only the electromagnetic force is required, but also various problems are caused due to the disturbance of the molten metal supply from the molten steel supply nozzle 20, which causes the surface defect of the cast piece.

As described above, in each case, large and unstable swells 23A and 23B were formed on the surface of the molten metal, which was one of the causes of surface defects. As a method of solving such a problem, instead of a general straight type single molten metal supply nozzle, the molten metal supply nozzle becomes a fan type, and the molten metal is dropped directly downward, in the lateral direction which is the short side direction. There is also a method to give no flow or to flow the molten metal in the circumferential direction of the roll, but in this case, since the molten metal supply nozzle has a special shape, it becomes expensive, and there is a big limitation to use it for commercial-based actual production. .

An object of the present invention is to insert a dam having a simple and inexpensive shape into the space inside the mold roll and suppress the melt flow from the melt supply nozzle by the dam.
The point is to provide a twin roll type thin plate continuous casting machine that does not directly apply to the short side weir.

[0010]

In order to achieve the above object, the first aspect of the present invention is to supply a molten metal from a molten metal supply nozzle to a space formed by a pair of rolls facing each other, and In a twin roll type thin plate continuous casting machine that presses the metal solidified layer generated on the roll surface by rotating in the sandwiching direction to manufacture a thin plate from the molten metal, between the molten metal supply nozzle and the short side weir , A dam for flow control that is made of refractory is installed.

A second aspect of the present invention is the twin roll type thin plate continuous casting machine according to the first aspect of the present invention, wherein the surface of the dam facing the molten metal supply nozzle is a concave arc surface in cross section,
In addition, many passage holes are formed.

[0012]

According to the structure of the first aspect of the present invention described above, the molten metal flow supplied from the molten metal supply nozzle toward the short-side weir side is
The flow can be suppressed (reduced) by hitting the surface of the dam, and the flow will reach a short side weir side as a slow flow, so there is no swelling on this short side weir, and uniform dynamic pressure on the short side weir. Will be given.

According to the structure of the second aspect of the present invention, the molten metal flow supplied from the molten metal supply nozzle toward the short-side weir side is
The flow can be suppressed (reduced) by hitting the concave arc surface of the dam, and separated in the left and right direction at the part with the curvature of the concave arc surface, flowing along the curvature while passing through the dam. It can be flowed while diffusing through the holes to the short-side weir side.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 3, the twin roll type thin plate continuous casting machine supplies a molten metal 5 from a molten metal supply nozzle 4 to a space 3 formed by a pair of rolls 1 and 2 facing each other, and rolls 1 facing each other. , 2 are rotated in a direction in which the metal solidified layer formed on the roll surface is pressure-bonded to produce a thin plate 6 from the molten metal 5. The supply port 4A of the molten metal supply nozzle 4 faces the short-side weir 7, and a flow-controlling dam 10 made of refractory material is installed between the molten-metal supply nozzle 4 and the short-side weir 7. There is.

The dam 10 is basically formed in the shape of an inverted triangle plate, and has an upper portion protruding from the molten metal surface and a gap between the roll surfaces of the rolls 1 and 2.
g is formed. The dam 10 is shown in FIG.
As shown in FIG. 6, a surface facing the molten metal supply nozzle 4 is formed into a concave arc surface 11 having a curvature r in a cross section, and the lower part is
It is formed on an arc surface 12 that is closer to the molten metal supply nozzle 4 in the lower part. The surface of the dam 10 facing the melt supply nozzle 4 side is formed with a flange portion 10A having a predetermined length a and width b from both side edges to the lower edge.

The dam 10 also has a concave arc surface 11 and an arc surface 12.
To a surface facing the short-sided weir 7, a large number of through holes 13 are formed. At this time, the passage holes 13 are formed in a trumpet shape in which the inner diameter d ₁ on the inlet side on the molten metal supply nozzle 4 side is larger than the inner diameter d ₂ on the outlet side on the short side dam 7 side. The outlet flow velocity is moderated.

Next, an example of the dimensions of each part in this embodiment will be described. The radii R of the rolls 1 and 2 are 600 mm. The molten metal surface height H is an important value for stable casting, but in the embodiment, it is 40
It is 0 mm. However, empirically, [0.5R <H <0.75R]
Within the range, stable casting is possible. Therefore, the width L of the molten metal surface is uniquely determined by the radius R and the height H of the molten metal surface, and is 308 mm in this embodiment.

The molten metal supply nozzle 4 is usually installed at the center of the width of the rolls 1 and 2 used in this method. Since the roll width used was 1100 mm, the molten metal supply nozzle 4
The distance C ₁ to the position of the dam 10 from the dam from Tanhenseki 7
The relationship with the distance C ₂ to the position of 10 is [C ₁ + C ₂ = 55
0 mm]. Here, the position of the dam 10 is arbitrary, but the required shape changes depending on the installation position. That is, if the distance C ₁ from the molten metal supply nozzle 4 to the position of the dam 10 is short, the length a of the collar portion 10A is long, and if the distance C ₁ is long, the length a may be short, but it is approximately 5 to 15 mm. Range is good.

Furthermore, the width, thickness, and height of the dam 10 are
Although it is determined by the shape of the curvature r of the concave arc surface 11 and the gap g required between the dam 10 and the rolls 1 and 2, the gap g is preferably 5 to 20 mm.

The operation of the above embodiment will be described below. As shown in FIGS. 1 and 2, the molten metal supplied from the supply port 4A of the molten metal supply nozzle 4 toward the short-side weir 7 side hits both arc surfaces 11 and 12 of the dam 10, and these arc surfaces 11 ， 12
Is separated in the left-right direction at the part with the curvature r of
While flowing along the flow path, it flows through the passage hole 13 formed in the dam 10 toward the short side weir 7 side while diffusing. Therefore, the molten metal flow from the molten metal supply nozzle 4 collides with the dam 10 and is suppressed (reduced) to become a slow flow, and the short-side weir 7
Since it reaches the side, the short-side weir 7 does not rise and a uniform dynamic pressure is applied to the short-side weir 7.

As described above, when the molten metal from the molten metal supply nozzle 4 is separated in the left-right direction at the portion with the curvature r, its flow escapes directly to the roll surface.
It will be prevented by 10A. At this time, the curvature r given to the dam 10 is determined by the position in the mold where the dam 10 is installed. The position at which the dam 10 is installed is determined by the installation of the temperature measuring member on the surface of the molten metal and the level sensor of the molten metal surface, but it may be installed anywhere if there are no restrictions. However, there is a relationship between the distance C ₁ and an appropriate curvature r, and a smaller curvature r is preferable as the dam 10 is closer to the molten metal supply nozzle 4, and a larger curvature r is preferable as the dam 10 is farther from the molten metal supply nozzle 4, The range of the good flow is as shown in FIG.

The molten metal that collides with the dam 10 moves to the short-side weir 7 side through the group of passage holes 13 formed in the dam 10, and at this time, the inlet-side inner diameter d _{1 is different from the} outlet-side inner diameter d. _{Since 2} is large, the outlet flow velocity will be moderated.

FIG. 8 shows the required hole diameter of the passage hole 13. Here, it is desirable that the inlet side inner diameter d ₁ is thin, but if it is 5 mm or less, it may be blocked, and if it is 12 mm or more, the dam is
The effect of slowing through 10 is weak. And the inner diameter d on the outlet side
_{Although 2} is determined from the inlet side inner diameter d ₁ and the obtained flow velocity, it may be determined from the number of the passage holes 13 arranged with reference to 1.5 times the inlet side inner diameter d ₁ . Further, the inlet side inner diameter d ₁ is made small when the dam 10 is close to the molten metal supply nozzle 4, and is made large when the dam 10 is separated from the molten metal supply nozzle 4.

[0024]

According to the first aspect of the present invention having the above-described structure, a simple dam shape is simply inserted into the space inside the mold roll without using a fan-shaped special and expensive nozzle.
The flow of molten metal from the nozzle for supplying molten metal to the short-sided weir can be suppressed by this dam so that it is not directly applied to the short-sided weir, and the problem caused by the lateral flow of molten metal can be solved at low cost. .

That is, when a refractory or ceramics was used for the short-side weir, the surface of the molten metal was not disturbed, and the cleanliness of the surface of the cast piece could be improved. In this case, in order to keep the surface temperature of the short-side weir at a high temperature, it is effective to heat from the back side of the short-side weir during casting. If a short-side weir that uses electromagnetic force is used as the short-side weir, the molten metal does not directly collide with the short-side weir that uses electromagnetic force, so that the required electromagnetic force can be reduced and the device can be simplified. In other words, the molten metal flow can be made uniform, which is effective in preventing defects in the cast slab.

Further, according to the second aspect of the present invention having the above structure, the molten metal flow from the molten metal supply nozzle collides with the concave arc surface of the dam, and is then separated in the left-right direction at the portion with the curvature of the concave arc surface. Then, while flowing along the curvature, it can flow while diffusing to the short-side weir side through the passage hole, and the flow can be suppressed more effectively.

[Brief description of drawings]

FIG. 1 is a partially cutaway plan view of a main part of a twin roll type thin plate continuous casting machine showing an embodiment of the present invention.

FIG. 2 is a side view of a main part of the twin roll type thin plate continuous casting machine.

FIG. 3 is a front view of a main part of the twin roll type thin plate continuous casting machine.

FIG. 4 is a plan view of a dam in the twin-roll type thin plate continuous casting machine.

FIG. 5 is a side view of a dam in the twin-roll type thin plate continuous casting machine.

FIG. 6 is a front view of a dam in the twin-roll type thin plate continuous casting machine.

FIG. 7 is a graph showing the required curvature of the dam surface in the twin roll type thin plate continuous casting machine.

FIG. 8 is a graph showing a diameter of a through hole required for a dam in the twin roll type thin plate continuous casting machine.

FIG. 9 is a side view of a main part of a twin roll type thin plate continuous casting machine when a short side dam is a refractory material in a conventional example.

FIG. 10 is a side view of a main part of a twin roll type thin plate continuous casting machine when another short side weir is an electromagnetic weir, showing another conventional example.

[Explanation of symbols]

 1.2 Roll 3 Space 4 Molten metal supply nozzle 4A Supply port 5 Molten metal 6 Plate 7 Short side weir 10 Dam 10A Flange 11 Recessed arc surface 12 Arc surface 13 Pass hole

Claims (2)

[Claims] 1. A metal coagulation layer formed on a roll surface by rotating a pair of rolls facing each other in a direction sandwiching the rolls while supplying the melt to a space formed by a pair of rolls facing each other. In a twin-roll type thin plate continuous casting machine that crimps and produces thin plates from molten metal, a dam for flow suppression made of refractory was installed between the molten metal supply nozzle and the short side weir. Characteristic twin roll type thin plate continuous casting machine. 2. The twin roll type thin plate continuous according to claim 1, wherein the dam has a surface facing the molten metal supply nozzle, which is a concave circular arc surface in cross section, and has a large number of through holes formed therein. Casting machine.