JPS6116214B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to continuous casting of metal, and its purpose is to obtain slabs of uniform width (and thickness).

In recent years, production of steel slabs by continuous casting has become popular. In such a continuous casting method, for example, Japanese Patent Publication No. 47-25572 discloses a method of changing the cross-sectional dimension, especially the width dimension, of a slab without changing the mold during continuous casting. The width dimension is changed by this method as shown in FIG.

In other words, each figure from A to E shows the process of changing the cross section from slab B with a predetermined width dimension to a slab with a larger width. The position of the side water cooling wall 3 of the mold 1 is enlarged to a desired width.

Next, the vertical movement of the upper and lower water-cooled molds 1 and 2 is stopped, and the withdrawal of the slab B is also stopped, and the injection amount of molten steel A is increased as shown in C, to the injection level 5 of the upper water-cooled mold 1.

During this time, even if the slab is pulled out to the outer periphery of the molten steel A in the mold for 20 to 50 seconds, although it varies depending on the cross-sectional area of the slab, a good-quality outer shell (shaded area of slab B) is formed. .

Thereafter, as shown in d, the position of the side water-cooled wall 3 of the lower water-cooled mold 2 is aligned with the position of the side water-cooled wall 3 of the upper water-cooled mold 1.

As a result, the upper end of the lower water-cooled mold 2 is separated from the stepped portion C formed by changing the width dimension of the slab B, so that the vertical movement of the upper and lower water-cooled molds 1 and 2 is started, and at the same time, the slab B is pulled out. Start with.

Next, as shown in E, the molten steel injection level is lowered to injection level 5 of the lower water-cooled mold 2, or
Alternatively, continuous casting is performed in a normal state without lowering the casting. Note that 4 indicates an injection nozzle.

However, as mentioned above, the drawing of the slab is stopped (20 to 50 seconds) until a sufficient shell is formed around the molten steel in the upper side water-cooled wall, so in the situation shown in Figure C. , the part directly below step C becomes supercooled, and as shown in Figure 2, that part (approximately
1m) was large, and the width (and thickness) was insufficient compared to the normal width L.

Therefore, in the past, cutting was performed at this insufficient width portion, but this resulted in a decrease in the yield of slabs. The same drawback occurs when the width is changed to a narrower width, contrary to the case shown in FIG.

The basic idea of this invention, which was made to eliminate the above-mentioned drawbacks, is to continuously widen the side water cooling wall of the mold (called Y change) in the area where the width (and thickness) of the slab is insufficient. The idea is to form an enlarged slab width portion by an amount commensurate with shrinkage.

By doing this, it takes on a Y-shaped shape with a widening width immediately after, but after shrinking it becomes uniform in width (and thickness).
This is what becomes the cast piece.

The method of the present invention will be specifically explained below with reference to the drawings.

First, the case of width enlargement change will be explained.

In Figure 3, if the width is expanded based on the operation in Figure 1 while casting slab B of a predetermined width is being cast, the width will be insufficient due to shrinkage before stopping drawing for the width expansion operation. In part D, its starting point E
From then on, the interval between the side water cooling walls is continuously widened to form an enlarged slab width section F at section D (Y change). The amount of the enlarged portion F is commensurate with the shrinkage.

Note that the width changing mold and the width changing method are not limited to those exemplified above.

Examples are shown below.

Example: When a slab with a width of 1,600 mm is being cast at a casting speed of V = 0.90 m/min and expanded to a width of 1,800 mm by the operation shown in Figure 1, the side water cooling wall of the mold is continuously expanded from 4,000 mm before the expansion point. Then, it was widened by 20mm at the width expansion point.

After that, drawing was stopped, the width was expanded to 1800 mm (53 seconds), then drawing was resumed, and continuous casting was continued with a width of 1800 mm. The width of the obtained slab was as follows, and a slab of uniform width was obtained.

Width of the pre-casting part: 1603mm Width just below the width expansion point: 1600mm Width of the width expansion part: 1801mm On the other hand, in the case where the present invention was not carried out, the results would be as follows.

Pre-casting width 1602mm Width just below the width expansion point 1581mm Width of the width expansion part 1802mm As described above, according to the present invention, in continuous casting, the width of the slab (and This method can easily and reliably solve the problem of insufficient thickness and obtain slabs of uniform width, which greatly contributes to improving the yield of slabs.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the steps of the width changing method, FIG. 2 is an explanatory diagram of problems that occur when the width is changed, and FIG. 3 is an explanatory diagram of the method of this invention. 1... Upper water-cooled mold, 2... Lower water-cooled mold, 3
...Side water cooling wall, 4...Injection nozzle, 5...Injection level.

Claims (1)

[Claims] 1 When changing the slab width during continuous casting, before stopping the withdrawal of the slab, the interval between the side water cooling walls of the mold is continuously expanded to create a width due to supercooling shrinkage directly below the slab width change area. A continuous casting method characterized by forming an enlarged slab width portion in an amount commensurate with the shortage.