JPH01284463A - Short wall side plate for continuous casting machine for cast strip - Google Patents

Abstract

PURPOSE:To improve the yield of a cast strip and to stabilize casting by arranging projecting part at both edges of tapered part in short wall side plate, making a recessing face shape of mold surface and gradually reducing the projecting size downward. CONSTITUTION:The projecting parts 5 are arranged at both edges of the tapered part 2 in the short wall side plate 1 and gradually reduced downward and formed so as to become the fixed width B at lower part C of the tapered part 2. Both side parts of the mold having the recessing face shape are formed with cooling copper plate and the part except the recessing face bottom part 3 and inclined face 10 is constituted of heat insulating refractory 13. Cast molten metal forms solidified shell on the mold surface of the short wall side plate 1, but the shell between the ridge line 7 of the projecting part 5 and refractory 13, receives in order bending action and is included into the solidified shell at a long wall part, and the development of the solidified shell at the inclined face 10 is restrained. By this method, as double skin and casting flash in the short wall part 1 are reduced, the yield of the cast strip is improved. The casting is stabilized with reduction of the casting flash.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a short side plate of a continuous thin slab casting machine.

In particular, the present invention relates to a short side plate that cooperates with a belt circulating body to constitute a casting space of a continuous thin slab casting machine.

[Conventional technology]

In a continuous casting machine that directly and continuously casts thin slabs such as sheet bars from molten metal, a pair of metal belt circulation bodies that circulate while maintaining a predetermined interval are located between the belt circulation bodies. It is known to form a tapered casting space by cooperating with a short side mold that is in close contact with the mold. In such a continuous casting machine, the conventional short side plate is
The surface shape of the mold is planar, and
As described in Japanese Patent No. 640, the tapered part where the slab thickness changes is made of a refractory to prevent the formation of a solidified shell, and the straight part is made of a cooled copper plate. Also, JP-A-58-21
There is also a short side plate described in the 8360 publication, and this short side plate is provided with a cooling copper plate 52 at the outer edge of a refractory 51 provided at the tapered part of the short side side plate 50, as shown in FIG. .

[Problem to be solved by the invention]

Each of the short side plates in the above-mentioned prior art has an insulating region of refractory material 51 in the tapered portion, thereby maintaining the surface temperature of the mold above the solidification shell formation inhibition temperature and preventing the formation of a solidification shell. However, depending on the flow state of the molten metal in the casting space and the casting conditions, it is difficult to constantly maintain the surface temperature of the refractory above the solidification shell formation inhibition temperature.

As shown in FIG. 12, solidified shells were observed not only on the surface of the cooling copper plate 52 but also on the surface of the refractory 51.

Since the conventional short side plate had a flat mold surface shape,
The solidified shell generated on the surface of the refractory has caused the following problems. That is, as the molten metal poured into the mold is drawn downward from the molten metal surface a by tapering casting, it undergoes tapering correction and its thickness is reduced as shown in FIGS. 13(A) to 13(C).

Therefore, as the solidified shell generated on the refractory surface is pulled downward, it collapses into the mold while undergoing compressive fracture, and is folded and shaped. In addition, when compressive fracture is performed, the metal belt 53 for the long side is caused by the fracture reaction force to
0 to release the contact state, and a gap is created between the two, the molten metal 54 enters into this gap, and the hot water pourer 55 is likely to form. As a result, the short sides of the cast slabs had the problem of double skin, microcracks due to folding and molding, and casting due to pouring, which remained as product defects because they were not crimped during rolling in the next step.

Further, when the hot water jug 55 is rapidly cooled, the belt circulating body 52 may stop due to metal resistance, or the solidified shell may be torn off, ie, breakout occurs, starting from the rapidly cooled metal.

Further, the conventional short side plate has a planar mold surface and is inclined so as to become narrower downwardly with respect to the belt circulation body by an amount corresponding to shrinkage in the slab width direction during casting. For this reason, as the metal belt circulation body moves downward, dust, fine metal pieces, etc. attached to the belt surface tend to enter between the short side plate and the belt circulation body, and the short side plate is damaged by this intruding foreign matter. There was a problem. Furthermore, if this foreign material enters near the hot water surface, a gap is created between the short side plate and the belt circulation body due to the foreign material, causing the above-mentioned hot water pouring problem.

The purpose of the present invention is to provide a thin slab continuous casting machine that improves the quality of the short side of the slab, reduces breakout during casting, and prevents foreign matter from entering between the short side plate and the belt circulation body. The purpose of the present invention is to provide a short side plate.

[Means to solve the problem]

The above purpose is to provide protrusions that protrude toward the casting space on both edges of the tapered part of the short side plate, make the mold surface of the tapered part concave, and gradually reduce the amount of protrusion of the protrusions downward. This is achieved by making the width of the bottom of the concave shape match the width of the straight portion of the short side plate.

[Effect]

The concave-shaped protrusion has a slope in which the ridgeline of the slope spreads relative to the belt circulation body, so the solidified shell generated on the slope of the concave-shaped protrusion is tapered to the ridgeline of the slope as it goes downward. While undergoing bending correction along the belt circulation body, the belt is sequentially incorporated into the long-side solidified shell formed on the belt circulation body.

As a result, the compressive fracture phenomenon of the solidified shell on the same plane, which conventionally occurred in the process of tapering casting, is converted into a correction phenomenon that replenishes the long side solidified shell, and compressive fracture of the solidified shell no longer occurs. Further, since the ridge line of the slope of the concave protrusion is inclined toward the lower floor, foreign matter attached to the belt circulation body is difficult to enter between the short side plate and the belt circulation body.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 10.

1 to 3 show a short side plate 1 according to an embodiment of the present invention. It consists of a straight part 3 having a constant width at the lower part C of the part 2. Projections 5 protruding toward the casting space 4 are formed on both side edges of the tapered portion 2, so that the mold surface of the tapered portion 2 of the short side plate 1 has a concave shape. The concave bottom part 6 is flush with the straight part 3, and its width B is also equal to the width B of the straight part.

The amount of protrusion of the protruding portion 2 gradually decreases from the -F portion of the tapered portion 2 toward the bottom, and the amount of protrusion becomes zero at the joint C with the straight portion 3. FIGS. 3(A) to (C) show I[I
Cross-sectional views along the A-HA line, the mB-mB line, and the mc-mc line are shown, and the apex a of the protrusion 5 in these cross sections
, b', c (c is also a point on the straight part 3) and the ridge line 7 including the apex e of the protrusion at the top of the tapered part 2 is approximately 10 to 20 cm wide on the outer surface of the short side plate 1. A protruding edge surface 8 is formed and a slope 10 is formed between the ridge 7 and the side edge 9 of the concave bottom 6. The edge surface 8 and the slope 10 are cooled by cooling channels 11 provided inside the short side plate 1.

Both side edges of the concave shape are made of cooling copper plates as part of the mold body, and a cooling area 12 of a constant width is formed on both side edges, and the entire area of the concave bottom 3 and the remaining part of the slope 10 is made of heat-insulating refractory material. 13 in order to suppress the formation of solidified shells as much as possible. Further, a cooling water channel 14 is provided on the back side of the concave bottom portion 3 to prevent thermal deformation and temperature rise of the mold body. Furthermore, cooling channels 15 are also provided inside the straight portion 2 of the short side plate 1.
is provided to powerfully cool the entire short side plate 1.

4 to 8 show the overall configuration of a continuous thin slab casting machine 2o incorporating the short side plate 1 of this embodiment. This continuous casting machine 2o continuously casts thin slabs with a thickness of 50 m or less from molten metal, and has a plurality of guides arranged facing each other while maintaining a predetermined interval to hold the molten metal, solidified shell, and slab. It has a pair of metal belt circulation bodies 22 that are circulated by rollers 21, and these belt circulation bodies 22
A pair of short side plates 1 are located between them and are in close contact with both side edges of the belt circulation body. A tapered casting space 4 is formed by the belt circulation body 22 and the short side plate 1. The casting space 4 has a similarly tapered shape corresponding to the shape of the tapered portion 2 of the short side plate 1, thereby reducing the gap between the belt circulation body 22 and the immersion nozzle 23 in the wide upper part. Since the amount of metal injected into the casting space can be secured, the liquid level of the molten metal 24 during casting can be stabilized. The continuous casting machine 20 has guide rollers 21
It also has a tensioning device [25] consisting of a hydraulic power actuator or the like that applies tension to the belt circulating body 22 by applying tension to the belt circulating body 22, and a cooling pad 26 that cools the belt circulating body 22 from the back side thereof.

In the above configuration, the molten metal 24 injected into the casting space 4 from the immersion nozzle 23 flows through the belt circulating body 2.
2, it is pulled out downward while being cooled and solidified. At this time, a solidified shell is also generated on the mold surface of the short side plate 1. Among these solidified shells, the solidified shell generated in the cooling zone 12 between the ridgeline 7 of the slope 10 and the heat insulating refractory 13 is caused by the tapered shape of the short side plate 1 and the gradually decreasing shape of the protrusion amount of the protruding portion 5. Since the ridgeline 7 of the protrusion 5 is inclined toward the bottom with respect to the belt circulation body 22 (see FIG. 7), as shown in FIGS. 9(A) to 9(C), the apex a is
As it goes downwards, it is sequentially bent along this ridgeline 7 and is incorporated into the long-side solidified shell on the belt circulation body 22, and reaches the starting point C of the straight section 3.

A solidified shell is also formed in the range of the refractory 13 on the slope 10, for example, when the temperature of the refractory has not risen sufficiently immediately after the start of casting. Like the solidified shell described above, this solidified shell is also subjected to a bending action sequentially along the ridge line 7 as it goes downward by tapering casting, and is incorporated into the long side solidified shell.

On the other hand, even if a solidified shell is generated at the bottom 6 of the mold surface in the same way as the slope 10 of the refractory 3, since the bottom 6 is flush with the straight part 3 and has the same width, the solidified shell is not bent in any way. It advances downward without being affected by the metal, is further cooled in the water-cooled metal region c-d of the straight section 3, and forms a strong solidified shell that can withstand the static pressure of the molten metal.

As described above, in this embodiment, the protrusion 5 is provided on the short side plate 1.
By providing a slope 10 including a cooling zone 12 and an insulating refractory 13, the generation of a solidified shell on the slope 10 is suppressed as much as possible, and the solidified shell that is formed remains thin by tapering casting and is attached to the short side plate. 1 is sequentially subjected to straightening by bending action along the ridge line 7 to form the long side surfaces of 18 pieces. This bending straightening force changes depending on the solidified shell thickness and the casting speed, but the bending straightening force changes depending on the solidified shell thickness and the casting speed. 7~15m/si
In the steel experiments conducted at n, it was confirmed that because the speed was high, the thickness of the formed solidified shell was thin, and it had almost no effect on the drawing power.

The condition of the skin of the slab was thus greatly improved by providing the protrusion 5 and the accompanying slope 10 and performing tapered casting. That is, as shown in FIG. 10, the solidified shell of the slab has been bent and straightened from the hot water level a to the level corresponding to the lower end C of the slope 10 by tapering casting, but at this time, the width of the concave bottom 6 B, the ridgeline 7 of the protrusion 5 on both sides
When the maximum width of the aI piece is set to 81, in the conventional short side plate without the protrusion 5, the surface width equivalent to 2Bl of the formed solidified shell undergoes compression failure, causing roughness of the aI piece. In the embodiment, if the long side width of the casting space 4 is [4, and the maximum length of the protrusion 5 is Ll, then geometrically, it will be compressed by 2 (,/Try2+HyakuryoZLL). become. Here, the protruding corner seat θ is 45
If it is assumed that L1=81, the above formula % formula % is obtained. In other words, the compression length decreases to about 1/2.4, and most of the compression length is absorbed as replenishment for solidification shrinkage on the long side of the slab and as compressive strain in the long side direction of the slab.
A compressive fracture phenomenon is less likely to occur in the width portion B of the short side, and a slab with a good cast surface can be obtained. According to the results of experimental casting, it has been found that the protrusion angle θ is preferably in the range of 30° to 60° in terms of the surface condition of the slab and the manufacture of the short side plates.

On the other hand, as shown in FIG. 7, the ridge line 7 and the edge surface 8 of the short side plate 1 are inclined upward toward the moving direction of the belt circulating body 22 and come into contact with the belt circulating body 22. Due to the movement of the circulating body 22, the short side plate 1 and the belt circulating body 2
2, the edge surface of the short side plate can be effectively protected.

Note that the short-side side plate of the present invention exhibits the same function even when used as a short-side side plate for a twin-roll continuous casting machine.

[Effects of the Invention] According to the present invention, protrusions are provided on both side edges of the short side plate,
By making the inner surface of the short side plate concave, it is possible to alleviate the compressive fracture phenomenon of the solidified shell on the short side during the tapering casting process, thereby preventing the occurrence of double skin or casting on the short side of the slab. It can be reduced to a level that does not interfere with rolling, and the yield of slabs can be greatly improved. Since the occurrence of cast sagging is reduced, breakouts are also reduced, and stable casting is possible. During the molten metal and garbage.

Since fine metal pieces do not enter, there is an effect that damage to the end faces of the short side plates can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a short side plate according to an embodiment of the present invention, and FIG. 2 is a longitudinal cross-sectional view taken along the line nn. FIG. 3(A), FIG. 3(B), and FIG. 3(C) are respectively It! of FIG. 2. A-I[[A line, II[B-1
11B line, a cross-sectional view along the mc-mc line, Fig. 4 is a cross-sectional elevational view of a thin cast side continuous casting machine incorporating the above short side side plate, Fig. 5 is a cross-sectional view taken along the line ■-■ of Fig. 4. A cross-sectional view along the line. Figure 6 is an enlarged plan view of the continuous casting machine shown in Figure 4;
The figure is a sectional view taken along the line ■-■ in FIG. 6, FIG. 8 is a sectional view taken along the line ■-■ in FIG.
), Figure 9 (C) is Figure 3 (A), Figure 3 (B), Figure 3
FIG. 10 is a perspective view showing the formation state of the solidified shell at a position corresponding to the cross section shown in FIG. 10. FIG.
The figure is a perspective view of a conventional short-side side plate, FIG. 12 is a cross-sectional perspective view showing the pouring phenomenon with a conventional short-side side plate, and FIG. 13 (A).
FIGS. 13(B) and 13(C) show the state of formation of a solidified shell by the conventional short side plates. FIGS. 9(A) and 9(C)
B) is a diagram corresponding to FIG. 9(C). DESCRIPTION OF SYMBOLS 1...Short side plate, 2...Tapered part, 3...Straight line part, 4...Casting space, 5...Protrusion part, 6...Bottom part,
7...Ridge line. DESCRIPTION OF SYMBOLS 10... Slope, 13... Refractory, 20... Thin cast side continuous casting machine, 22... Belt circulation body. Raku Misaki 2nd - Figure 3 High 4 - Ward Rate 5 Figure Hi T Hi■ Minus 6 Figure 躬°3 3rd Figure Akira q Ward 10 Figure 11 Graduation 1□9 Figure 13 (Al (8) (C) 婢正方形

Claims (1)

[Claims] 1. Located between a pair of belt circulating bodies that circulate while maintaining a predetermined interval for holding molten metal and slabs, and tightly attached to both side edges of these belt circulating bodies. In a short side plate of a continuous thin slab casting machine, the short side plate of a continuous thin slab casting machine consists of an upper tapered part and a lower straight part that define a casting space in cooperation with the belt circulation body, and both edges of the tapered part. A protrusion facing toward the casting space is provided to make the mold surface of the tapered part concave, the amount of protrusion of the protrusion gradually decreases downward, and the width of the bottom of the concave shape is set to be equal to the width of the straight part. A short side plate of a thin slab continuous casting machine characterized by having the same width. 2. In the short side plate according to claim 1, a cooling area of a constant width is provided on both side edges of the concave shape, and the remaining portion including the bottom of the concave shape is made of a heat insulating refractory. 1. A short side plate of a thin slab continuous casting machine, characterized in that: