JPS63149044A - Short side plate for continuous casting machine for cast strip - Google Patents

Abstract

PURPOSE:To easily evade the development of insertion of molten metal and to improve the yield of cast strip by arranging a cooling part at both edge parts contacting with a circulating bodies on the short side plates composing of a casting space together with the circulating bodies and gradually increasing the width from meniscus part to the casting direction. CONSTITUTION:Metallic belts 1, 2 as one pair of circulating bodies arranged as facing to each other, while maintaining interval for holding the molten steel, solidified shell and cast strip, are circulately moved through plural pieces of guide rolls. Further, the cast space is composed of the metallic belts 1, 2 and one pair of short side plates 5, 6 brought into closely contact with the both side part. The cooling part 5d connecting with the straight part 5b composing from cooling metal plate at lower part is arranged at both side edge parts of curved faces 5a on the upper parts of short side plates 5, 6 for the above continuous casting machine. Further, the width of cooling part 5d is made to gradually increase from the meniscus part to the casting direction. In this way, the development of insertion is avoided and the burr, double skin, etc., of the cast strip is prevented.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention aims to transform the casting space of a continuous thin slab casting machine, typically a belt caster, which directly casts thin slabs with a thickness of 50 mm or less from molten metal into a circulating body. It also relates to the structure of the short side plate.

(Prior art) JP-A-58-32551 (Document A) and JP-A-58-21
No. 8360 (Text, B) Each publication describes a continuous casting stage that directly and continuously casts thin slabs such as sheet bars from molten steel, that is, a continuous casting stage that moves circularly while maintaining an interval to hold the molten steel and slabs. The long sides of the slab are supported by a pair of metal belts,
On the other hand, there is a disclosure of a continuous casting machine in which a tapered casting space is formed by supporting the short sides of the slab with short side plates that are located between the metal belts and in close contact with the belts.

Therefore, the short side plate has a tapered shape, and in the short side plate disclosed in Document A, the curved surface part where the slab thickness changes is made of refractory material to avoid the formation of a solidified shell, and the straight part is made of a cooling copper plate. On the other hand, in the short side plate disclosed in Document B, the outer edge of the curved refractory is made of a cooling copper plate.

(Problems to be Solved by the Invention) Since the short side plates mentioned above all have a refractory insulation area on the curved surface, if appropriate casting conditions are not selected, a problem will occur between the short side plates and the metal belt. Avoiding hot water is difficult.

Therefore, it is an object of the present invention to provide a short side plate having a structure that can easily avoid the formation of hot water.

(Means for Solving the Problems) The present invention includes a pair of circulating bodies that move circularly while maintaining a gap for holding molten metal and slabs, and a pair of circulating bodies that are tightly connected to both sides of the circulating bodies. In the short side plate of the continuous casting machine, in which a casting space is formed by a pair of short side side plates in contact with each other, a cooling section is provided at both side edges in contact with the circulating body, and the width of the cooling section is gradually increased from the meniscus section in the casting direction. 1 is a short side plate of a continuous thin cast slab casting machine, which is characterized in that:

Now, a continuous casting machine to which short side plates according to the present invention are applied is shown in FIG. 1(a).

A metal belt 1, which is a pair of circulating bodies arranged facing each other while maintaining a gap for holding molten steel, solidified shells, and slabs.
．． 2, a plurality of guide rollers, 3a, 3b, 3c
, 3d and 4a, 4b, 4c, and 4d, and support the long sides of the slab with the metal belts 1 and 2, while being located between the metal belts 1 and 2 and in close contact with the metal belt. A tapered casting space is formed by supporting the short side surfaces of the slab with a pair of short side plates 5.6. By tapering the casting space, a gap can be secured between the immersion nozzle 7 and the metal belts 1 and 2, and the level of the molten metal during casting can be stabilized.

Note that 8 is a belt tension cylinder for adjusting the tension of the metal belts 1 and 2, and 9 is a cooling pad for cooling the metal belt 1.2 from the back side.

Next, the short side plate 5 shown in FIG. 1(b) will be explained.

The short side plate 5 has a curved surface fm5a that is wide at the top and gradually tapers toward the bottom, and a straight section 5b that has a constant width at the bottom of the curved surface section 5a, excluding both side edge portions of the curved surface section 5a. A lining layer 5C of refractory material is provided on the refractory, and cooling portions 5d continuous with the straight portions 5b are provided on both side edge portions of the curved portion 5a, and the cooling portions 5d and the straight portions 5b are water-cooled metal plates.

Furthermore, it is important to gradually increase the width of the cooling portion 5d of the short side plate 5 in the casting direction.

(Function) Prevention of casting when the short side plate according to the present invention is applied to a continuous casting machine will be explained in comparison with a conventional short side plate.

First, as shown in FIG. 2, a short side plate 10 whose curved surface portion is made of the refractory layer 10a and whose straight portion is made of the water-cooled metal plate 10b.
Continuous casting using this method will be explained based on FIG. 3.

In this case, the slab shell 11 in contact with the refractory layer 10a is pulled out while causing relative sliding without solidifying, so that a hot water jug 12b is often produced near the hot water jug 12a1 or the water-cooled metal plate 10b.

Furthermore, when the short side plate 13 shown in FIG. 4 is provided with cooling parts 13a on both edges of the curved surface part, the solidified shell generated in the water-cooled metal plate 13a is unevenly cooled as shown in FIG. etc., it falls into the mold and causes the hot water jug 12c to break out.

The hot water jug 12a is made of cast slabs, and the hot water jug 12b
This results in a double skin, and since both are not crimped during rolling, this remains as a product defect.

Among the above casting defects, the casting defect of the hot water jug 12a can be almost solved if the short side plates are of the type shown in FIG. 4, since solidified shells can be formed at the corners at an early stage. However, even with this type, it is difficult to avoid the hot water jug 12b. This is because, as shown in FIG. 5, the length of the solidified shell generated by cooling the short side is too long compared to the thickness a of the long side shell generated by cooling the metal belt, resulting in uneven cooling, and the solidified shell 11 is easily
This is because the mold falls inside the mold. Therefore, in order to prevent this, it is advantageous to make the solidified shell length of the solidified shell 11 smaller than the long side shell thickness a.

Continuous casting was performed using the short side plate shown in FIG. 1(b) under the experimental conditions shown in Table 1. As long as the solidified shell length was b≦2a, there was no collapse phenomenon of the solidified shell. Furthermore, it has been found that if the width C>0 of the cooling part 13a, no casting occurs.

Therefore, the width C of the cooling section is c=a+b, so from this, 0
Therefore, it is sufficient to satisfy C≦3a − (1).

Incidentally, the relationship between the width C of the cooling section and the occurrence rate of the hot water boiler is shown in FIG.

Further, the long side shell thickness a in the cooling section is generally determined by the following formula.

Here: the number of coagulation fixed, 10 to 25 mm for the cooling copper plate.
It becomes 15n.

β: Distance from the meniscus in the casting direction [m] ■=Casting speed Cm/min] From the above equations (1) and (2), the width C of the cooling section is determined by the following equation.

On the other hand, the collapse of the solidified shell is 1 from the meniscus.
Experimental results have shown that this occurs after the 00 mark. Therefore, the minimum value of C is l in equation (3)
It may be a value obtained by substituting =O, 1m.

Further, the maximum value c1 of C is 1/2 of the maximum slab thickness.

Cmax = C+ = (5) Therefore, the cooling part width C for preventing casting and pouring may be set to satisfy both equations (3) and (6).

As β increases, the shape of the cooling part width C becomes (3), (6)
Gradually increase the value within the range that satisfies j.

(Example) Example 1 When performing continuous casting under the conditions shown in Table 2, the preferred width of the cooling portion of the short side plate was determined using each of the above-mentioned formulas.

That is, from the above formulas (3) and (5), 0×C1≦
15 (mm) From the above formulas (3) and (6), we calculated 2.7≦C and ≦8.1 (mm), respectively (however, 220.1 m), and decided to use the short side plate according to this range. .

Therefore, the width of the cooling part is Co-5mm, C, = 10+
When continuous casting was carried out using a short side plate having a structure in which C6 to C gradually increased at n+n, no casting or double skin was observed in the obtained slab.

Table 2 Example 2 When performing continuous casting under the conditions shown in Table 3, the preferred width of the cooling section of the short side plate was determined using the above-mentioned formulas.

That is, from the above formulas (3) and (5), 0×C1≦
15 (mm) From the above equations (3) and (6), 1.6≦co≦4.9 (mm) was determined (however, 420.1 m), and it was decided to use a short side plate according to the range.

Therefore, the width of the cooling part is C8 = 3 mun, self = 10 mm, and C
When continuous casting was carried out using a short side plate having a structure in which the number of 6 to C1 gradually increased, no casting or double skin was observed in the obtained slab.

Table 3 (Effects of the invention) In conventional casting using short side plates, casting and double skin could not be avoided, but by applying this invention, casting can be improved to a level that does not cause problems at least in the rolling process. It is possible to reduce the occurrence of double skin, improve yield, and
It has become possible to cast stable slabs.

[Brief explanation of the drawing]

Figure 1 (a) is an explanatory diagram of the continuous casting machine, Figure 1 (b) is an explanatory diagram of the short side plate, Figures 2 and 4 are explanatory diagrams of the conventional short side plate, and Figures 3 and 4 are explanatory diagrams of the conventional short side plate. FIG. 5 is an explanatory diagram showing the occurrence of hot water pouring, and FIG. 6 is a graph showing the relationship between the width of the cooling part of the short side plate and the hot water pouring generation rate. 1.2... Metal belts 3a to 3d, 4a to 4d... Guide rollers 5, 6.
10.13...Short side plate 5a...Curved surface portion 5b...Straight portion 5C...
・Lining layer 5d, 13a...Cooling part 7...
- Immersion nozzle 8...Belt tension cylinder 9...Cooling pad 10a...Refractory layer 10b
... Cooled copper plate 11 ... Solidified shell 12a,
12b, 12c ”・'?a Insert Figure 1 (a) (b)

Claims (1)

[Claims] 1. A pair of circulating bodies that move circularly while maintaining a gap for holding molten metal and slabs, and a pair of short sides that are in close contact with both sides of the circulating bodies. In the short side plate of the continuous casting machine that forms a casting space with the side plate, a cooling section is provided at both side edges in contact with the circulating body, and the width of the cooling section is gradually increased from the meniscus section in the casting direction. Short side plate of continuous thin slab casting machine.