1. Field of the Invention
The invention concerns a process and equipment for producing thin slabs, whose cross section is reduced during solidification, in a continuous casting plant, whose strand guide following the mold has wedge-shaped, adjustable roll sections or strand segments for regulating the thickness of the strand or thin slab.
2. Description of the Related Art
It is known from EP 0 450 391 B1 that, in a thin slab casting machine, to support the cast strand, especially for soft reduction, symmetrically opposite roll supports can be provided below the continuous casting mold on both sides of the cast strand, the rolls of which are in working connection with the strand. Each roll support is mounted in a stationary frame and divided into segments that support several rolls, and each segment has adjusting devices. The roll-supporting segments are flexibly coupled with one another in such a way that each segment can be set and adjusted individually at any desired angle to the strand. Mechanical, hydraulic, or mechanical-hydraulic adjusting devices are used for this purpose.
DE 196 39 297 A1 describes a process and equipment for high-speed continuous casting plants with strand thickness reduction during solidification. The strand cross section is linearly reduced over a minimum length of the strand guide immediately below the mold. With the following further reduction of the strand cross section over the remainder of the strand guide (soft reduction) until at most immediately before the final solidification or the tip of the liquid crater of the liquid core, a critical deformation of the strand is avoided, taking into account the casting rate and the steel grade. EP 0 611 610 A1 also describes strand casting with distribution of the thickness reduction over the length of the strand guide, in which the casting of the strand is additionally followed by hot rolling of the slabs previously cut off from the strand.
The object of the invention is to develop a process and equipment of the type mentioned at the beginning, which allow optimized LCR (liquid core reduction) and reduce plant expenses.
In accordance with the invention, this object is achieved with a process for thin slabs in the thickness range of about 40β120 mm, in which the strand thickness is reduced only at a point of the strand guide below the first segment downstream of the mold in a region of the strand that has a liquid core by wedge-taper adjustment of the strand guide rolls there with a soft transition. This puts into practice the recognition, based on extensive operational experience, that, in the case of small thickness reductions, it is sufficient to act on the strand at only one point of the strand guide. Thus, it is no longer necessary to provide all segments with regulating or adjusting devices, which otherwise would require high capital costs and maintenance expense.
In any case, above all, at least the first segment immediately following the mold can be designed in a simple and maintenance-friendly way. The simple design of the first segment is especially advantageous due to the high risk of breakouts there, particularly if special steel grades, e.g., high-grade steels, are being cast. Furthermore, in the case of modernization, the simple design of the segments located between the mold and the reduction region makes it possible to retain the existing segments for this strand guide region, which limits the modernization costs only to a partial area of the continuous casting machine or plant and thus lowers the capital costs. In addition, an operation of the continuous casting plant can be realized, in which the liquid crater or liquid core can be shifted as far as possible towards the bottom, and a final solidification can always be achieved in the same region of the strand guide. This is independent of the given width of the strand that is about to be cast and of the casting rate.
In accordance with a proposal of the invention, the thickness is reduced in the range of 1β25 mm, depending on the casting format and the exact location of the adjusted segment performing the mini-reduction within the strand guide. The concrete location of the occurrence of the action on the strand is thus crucial to the corresponding degree of thickness reduction to be carried out.
In accordance with the invention, the equipment for carrying out the process has a pivoting point on the run-in side in a segment following the segment located directly after the mold and preferably load-regulated and/or position-regulated adjusting devices on the runout side. At least the first segment following the mold is thus not used for the thickness reduction and thus remains in its original parallel position of the strand guide, so that no hydraulic regulating devices are needed for this segment. For the following segment that is to be wedge-adjusted at one point in the strand guide, a simpler and less time-consuming wedge adjustment is achieved than in the case of a total wedge adjustment by adjusting devices due to the pivoting point on the run-in side.
A preferred embodiment of the invention provides that the segment performing the mini-reduction is subdivided, and only the strand guide rolls located in the upper partial segment are adjusted against the strand. This partial segment, which then has the pivoting point at the top and the adjusting device or devices on the runout side, means that the wedge adjustment is always followed by still another parallel section of the strand guide, even when the wedge adjustment occurs in the last segment of the strand guide.
In accordance with a proposal of the invention, adjusting cylinders located on the movable side are assigned to the driven rolls of the bending driver that follow the segments of the strand guide. These cylinders located on the movable side (in continuous casting plants, the fixed side is generally located in the direction of the turret supplying the ladles with the molten steel) produce the advantage that they automatically adjust to the thickness of the strand.
Further details of the invention are revealed by the following description of the embodiments illustrated in the drawings.
In the embodiment shown in
In contrast to the embodiment described above, in
A common feature of all of the embodiments is that at least the first segment 3 after the mold 2 (and, in accordance with
Number | Date | Country | Kind |
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100 57 160 | Nov 2000 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP01/13229 | 11/16/2001 | WO | 00 | 9/3/2003 |
Publishing Document | Publishing Date | Country | Kind |
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WO02/40201 | 5/23/2002 | WO | A |
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5577548 | Hohenbichler et al. | Nov 1996 | A |
5853043 | Takeuchi et al. | Dec 1998 | A |
6102101 | Hanazaki et al. | Aug 2000 | A |
6612364 | Streubel | Sep 2003 | B1 |
6701999 | Von Wyl et al. | Mar 2004 | B1 |
6712123 | Weyer et al. | Mar 2004 | B1 |
Number | Date | Country |
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4436328 | Apr 1995 | DE |
4403048 | Jul 1995 | DE |
196 39 297 | Mar 1998 | DE |
0329639 | Aug 1989 | EP |
0450391 | Oct 1991 | EP |
0611610 | Aug 1994 | EP |
9850185 | Nov 1998 | WO |
Number | Date | Country | |
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20040035550 A1 | Feb 2004 | US |