JPS6068147A - Secondary cooling method of multiple continuous casting billets - Google Patents

Abstract

PURPOSE:To prevent bending and cambering of billets and to improve productivity by casting the multiple billets with a continuous casting machine which casts single or plural billets while cooling the billets in the vertical and transvers directions with two cooling systems thereby maintaining the cooling balance in the transverse direction of each billet. CONSTITUTION:The top and bottom surfaces of respective billets 7 and the opposed surfaces 5, 5 of the adjacent billets are cooled by using two cooling systems; the 1st cooling systems 1A, 1B which enclose the region where the billets or billet arrays pass. The outside side faces 6, 6 of the outermost billet 7 of the billet array are cooled by using the 2nd cooling systems 2A, 2B. The billets are cast while the cooling balance between the surfaces 6, 6 and the surfaces 5, 5 is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention aims to improve the cooling balance in the left and right direction of the cross section of a slab in a continuous casting method using a continuous casting machine that can cast single or multiple strips in one strand. The present invention relates to a method for secondary cooling of multi-strip continuous cast slabs while maintaining the same temperature.

Conventional technology Conventionally, slab cooling in the secondary cooling zone in the so-called single-strip continuous casting method was performed only on a wide surface (1-1 bottom surface of the slab), for example, for slabs with a large aspect ratio of the slab cross-sectional dimension. Cooling was actively carried out, and the narrow side (side surface of the slab) in particular was not actively cooled.

As shown in Fig. 1, in the case of slab (S), even if the slab width changes from Fig. Since it is installed symmetrically with respect to the width direction of the slab (left,
(right) because the cooling imbalance does not occur. Bloom again (
In the case of B), cooling is performed on all four sides as shown in Figure 2, so even if the size changes from Figure (a) to Figure (b), the spray (sp) arrangement will be symmetrical. Because of this, the cooling imbalance of the slab does not occur in the bloom (B) as well as in the slab.

On the other hand, continuous casting of slabs from 2 to 1 shown in Fig. 3 is carried out.
In the so-called multi-strip casting method, due to the hierarchical relationship between the slab and the spray, two cooling methods are used, similar to those in the single-strip casting method described above.
When the next cooling is performed, there will be an imbalance in the cooling of the left and right sides of each slab in the direction of travel, resulting in bending of the slab,
It is known to cause a meandering phenomenon.

Therefore, in the secondary cooling method in the conventional multi-strip casting method,
As shown in FIG. 4, a method has been used in which a dedicated cooling system is provided for each number of cast strips. However, with this type of dedicated cooling system, the piping design, control system, etc. are complicated, and equipment costs are high. There were drawbacks such as the need for inspection and replacement at the time of system switchover, which required long downtime and labor.

To explain this conventional method in detail with reference to Figs. 3 and 4, Fig. 3(a) shows single casting of slab (S), and Fig. 3(b) shows twin casting.
Indicating the casting.

During twin casting, when casting with a single spray arrangement as shown in Fig. 3(a), the twin slabs are sprayed in the central spray (spray directed between the pieces) 4 as shown in Fig. 3(b).
The facing surface (narrow surface) 5 of the slab is cooled by the cooling process, and the vertical cross section of the slab is substantially parallel to the facing surface and the outside surface (narrow surface) 6 of the slab, which is not actively cooled. Cooling imbalance occurs in the steel, resulting in bending and meandering of the slab.

In response to this situation, it is common to add a cooling system for twin casting as shown in Figure 4 to a single cooling system, and as a result, the various problems associated with the congestion of equipment as described above are avoided. It forced the problem.

In particular, bloom's triplet PI construction and slab twin (tw
in) In a composite multi-strip continuous casting machine in which casting can be shared, the above-mentioned problems become even more complicated.

Purpose of the Invention The present invention is directed to a continuous casting machine.
Between multiple rows (for example, between single rows (2-1-) and multiple rows (?i)
In a continuous casting method using a continuous casting machine that can mainly cast multi-strip slabs, such as between multiple strips (for example, from two strips (three strips) to three strips (two strips)), Even if the casting center is changed in this casting, the maintenance work for the cooling system can be virtually eliminated without installing a complicated cooling system, and the horizontal direction ( It is possible to cast while maintaining the cooling balance (on the drawing),
To provide a method for secondary cooling of a multi-strip continuously cast slab without bending or meandering of the slab.

Structure and operation of the invention The present invention has been made in order to eliminate the drawbacks of the conventional method mentioned above and to achieve the above object. In a continuous casting method using a continuous casting machine capable of casting, a second slab cooling system is used to cool each slab using a two-slab cooling system that surrounds the passage area of the slab or row of slabs. The first cooling system is used to cool the first, F, and opposing surfaces of the adjacent slabs of each of the 21 slabs, and the second cooling system is used to cool the outer surface of the outermost slab in the slab row. This is a method for secondary cooling of multi-strip continuous cast slabs that maintains the cooling balance in the left and right direction on one cross section and performs viewing casting without causing bending or meandering of the slabs.

Hereinafter, the structure and operation of the present invention will be explained in detail.

As a result of various studies conducted prior to the completion of the present invention, the inventors of Wooden Engineering and others discovered that (1) a dedicated cooling system (orientated to the upper and lower surfaces of slabs (wide surfaces for slabs) that is common to different slab rows with respective casting centers); 1st
(2) A cooling system is installed to mainly cool the bottom surface of the slab (1). A flexible dedicated cooling system (second cooling system) is used to cool the outer surface of the outermost slab in the row of Pi strips, thereby achieving cooling balance in both directions on the slab cross section that is approximately parallel to the outer surface and the opposing surface. We found that it is possible to take

This will be explained below based on FIG.

Embodiment FIG. 5 is a cooling pattern showing an embodiment of the present invention, in which (a) is a triplet + [4 production time of bloom (B)].
(b) shows the twin casting of the slab (S). (IA)
is the top cooling system of the cast piece (brute or slab), (IB)
is a cooling system for the lower surface of the slab, and (IA) and (IB) constitute a first cooling system.

The amount of chilled tofu supplied can be set to an appropriate value by a control device (not shown) provided in the upper cooling branch pipe (IA), the lower cooling branch pipe (IB), or the refrigerant supply wood pipe (not shown).

(2A) and (2B) are the outer surface 6 of the outermost slab 7 in the slab row.
In the cooling system, similarly to the bottom cooling system, the refrigerant supply amount can be controlled individually or in common.

The refrigerant used in the present invention is generally water or a mixture of air and water, but the use of gas or other refrigerants is also included within the scope of the technical concept of the present invention.

Next, slab twin casting and bloom triple hM
An example of a method for cooling slabs in a continuous casting machine that can be used interchangeably will be described below.

The first surface casting conditions are shown.

Table 2 shows an example of the amount of cooling water supplied from each cooling zone in the secondary cooling zone (the cooling spray arrangement of each cooling zone is shown in FIG. 5) based on the casting conditions in Table 1. In addition, in Table 2, the amount of cooling water is n/min,
The cooling zone numbers are sequentially No. 001.2 from the mold side.
3...

Table 2 As a result, in this example, no bending or meandering phenomenon occurred in the slab, and therefore no operational troubles such as temporary stoppage of casting work occurred.

In addition, the amount of cooling water (by the cooling systems 2A and 2B) to the outer surface of the outermost slab in the present invention is estimated in advance through an off-line test, and adjusted and set by observing the meandering condition of the slab during actual casting. In this case, the spray of the upper and lower surface cooling system (IA, 18) provided with a sensor detects the amount of water injected into the opposing surface of the adjacent slab, and contributes to modifying the cooling of the outer surface of the outermost slab. I can do it.

Effects of the Invention As detailed above, the present invention has a simple device configuration, and even in a common casting method for multiple rows of slabs with different casting centers, bending of the slab does not occur, and therefore, bending (meandering) is avoided. There were no operational issues or troubles caused by this, and we were able to significantly improve productivity and work efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1(a) and 1(b) are explanatory diagrams showing an example of a cooling mode in the case of single-strip casting of a slab. FIGS. 2(a) and 2(b) are explanatory diagrams showing an example of a cooling mode in the case of single thread casting of bloom. FIG. 3 is an explanatory diagram showing (a) an example of a cooling method for single thread casting, and (b) showing a cooling mode when twin casting is performed using this method. FIG. 4 is an explanatory diagram showing an example of a dedicated cooling system in conventional multi-strip casting. FIGS. 5(a) and 5(b) are explanatory diagrams showing one embodiment of the cooling aspect of the present invention. 1A, IB・fight Φ 1st cooling system, 2A, 2B φ fist・2nd cooling system, Se 豐・slab, B... fight bloom, 3...ψ spray, 4・me central spray, 5@・Φ Opposite surface, 6.
・・Outside surface, 7◆・・Slab row installation side slab. Patent applicant: Nippon Steel stock agent Patent attorney 弗 2 Cow Figure 1 (a) (b) Figure 2 (a) (b) Figure 3 (b) Figure 4 (continued from page 1) [Phase] Inventor Akiji Murase To Kitakyushu City Nippon Steel Corporation 8, 1-1-1 Edamitsuhata Steel Works, Hatto-ku

Claims (1)

[Claims] In a continuous casting method using a continuous casting machine that can commonly cast single or multiple strips, is there a passage area surrounding the slab or row of slabs? In cooling each slab using the series of slab cooling systems, the first cooling system is used to cool the upper and lower surfaces of each slab and the opposing surfaces of adjacent slabs, and the second cooling system is A multi-strip continuous caster is used to cool the outer surface of the outer slab placed in a row of slabs, maintaining a cooling balance in the left-right direction at each slab cross section that is approximately parallel to the outer surface and the opposing surface. Secondary cooling method for cast slabs.