TUNDISH FOR A CONTINUOUS CASTING PLANT

Abstract

A tundish, in particular a tundish for continuous steel casting for placement between a steel casting ladle and a continuous casting mold, with an inlet region and an outlet region, wherein in the inlet region, molten steel can be supplied in particular through a ladle shroud and in the outlet region, the molten steel can be drained from the tundish in particular by means of a plug and an outlet opening; in the vicinity of the inlet region in the tundish, a threshold or ramp is provided, which forms a region of the tundish bottom into a cup or tundish; the threshold or ramp has at least one channel at the side, which locally reduces the height of the threshold or ramp or breaks through the threshold.

Claims

1. A tundish for continuous steel casting for placement between a steel casting ladle and a continuous casting mold, comprising: an inlet region in which molten steel can be supplied and an outlet region from which the molten steel can be drained from the tundish; a threshold or ramp in the vicinity of the inlet region in the tundish, wherein the threshold or ramp forms a region of the tundish bottom into a cup; the threshold or ramp has a respective channel at a side, which locally reduces a height of the threshold or ramp or breaks through the threshold; and the threshold has a height that is less than a height from the tundish bottom to a maximum bath surface of the tundish during operation.

2. The tundish according to claim 1, wherein the respective channel reduces the height of the threshold or ramp completely to a level of the bottom in the inlet region.

3. The tundish according to claim 1, wherein the channel has an inclination that corresponds to a shape of the bottom without the threshold.

4. The tundish according to claim 1, wherein the threshold has a height relative to the bath surface of less than 1:5.

5. The tundish according to claim 1, wherein a bottom of the channel has an inclination of 2° to 6° from the inlet region to the outlet region.

6. The tundish according to claim 1, wherein in the inlet region of the tundish, molten steel can be supplied through a ladle shroud and the molten steel can be drained from the tundish by a plug and an outlet opening.

7. The tundish according to claim 1, wherein the channel or channels have a width that does not exceed 30% of a width of the tundish interior overall.

8. The tundish according to claim 1, wherein the channel or channels is/are each delimited by a respective side wall and a channel side wall, which is formed by the threshold or ramp, as well as by a channel bottom.

9. The tundish according to claim 1, wherein the channel or channels is or are spaced slightly apart from the respective side wall by 0.01% to 25% of a width of the tundish interior.

10. The tundish according to claim 1, wherein walls delimiting the channel or channels respectively widen the channel starting from its channel bottom, in particular with an angle of 2.5° to 25°.

11. The tundish according to claim 1, wherein an area of the threshold or ramp is less than 50% of a total area of the tundish bottom.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The invention is explained by way of example below based on the drawings. In the drawings:

[0035] FIG. 1: is a very schematic depiction of a tundish according to the prior art in a view from above;

[0036] FIG. 2: shows a cross-sectional view of the tundish according to FIG. 1;

[0037] FIG. 3: is a very schematic top view of a tundish according to the invention;

[0038] FIG. 4: is a cut-away side view of the tundish according to FIG. 3;

[0039] FIG. 5: shows the results of numerical CFD calculations (RTD curves);

[0040] FIG. 6: shows a very schematic isometric, partially sectional view of the tundish according to the invention;

[0041] FIG. 7: shows a cross-section through a channel according to the invention at the bottom of the tundish;

[0042] FIG. 8: shows the flow profile at the inlet of steel into the tundish according to the prior art;

[0043] FIG. 9: shows the flow profile when steel is introduced into the tundish according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] A tundish 1 according to the invention is an elongated trough-like receptacle with two opposing end walls 2, 3 and two side walls 4, 5 connecting the end walls (FIG. 1 and FIG. 2).

[0045] The tundish 1 also has a bottom 6; an inlet region 7 and an outlet region 8 are provided along a longitudinal axis 9 of the tundish 1. In this case, the inlet region 7 is situated adjacent to an inlet-side end wall 2, while the outlet region 8 is embodied adjacent to an outlet-side end wall 3 so that basically, incoming steel flows through the receptacle along the longitudinal span of the tundish 1.

[0046] The bottom 6 of the tundish 1 can deepen extending in an inclined fashion from an inlet region 7 to an outlet region 8, where in this context, “extending in an inclined fashion” means that the depth relative to a bath level 10 increases.

[0047] At the bottom 6 of the tundish 1 toward the interior 11 of the tundish 1, a threshold 12 or ramp 12 is provided in such a way that it forms a recessed cup 13 in the inlet region 7 of the tundish 1. In particular, this cup 13 is embodied as recessed, rectangular, and trough-like. The threshold 12 or ramp 12 constitutes a closed boundary of the cup 13 oriented toward the interior 11 in the direction of the tundish outlet 8 and in particular, can have a slight inclination similar to a ski jump.

[0048] The tundish bottom 6 in this case can slope downward from an upper edge 12a of the threshold 12 with a sustained inclination 14 in the direction toward the tundish outlet 8. Preferably, the bottom 6 in the vicinity of the inlet region 7 and the outlet region 8 is flat relative to a bath surface 10. In this case, the “bath surface” 10 is intended to mean the maximum bath surface 10 during operation of the tundish 1. As the tundish 1 is being emptied, the bath surface drops from the maximum bath surface 10 during operation.

[0049] According to the invention, (FIG. 3 and FIG. 4), at least along a side wall 4, 5, the boundary of the cup 13 or the threshold 12 or ramp 12—in the direction toward the tundish outlet 8—is embodied with a channel-like breach 15, which extends from the upper edge 12a of the threshold 12 or ramp 12, preferably down to a level of the bottom 6 in the vicinity of the inlet region 7.

[0050] This ensures that residual steel can flow out of the cup 13 and travel into the outlet region 8.

[0051] To this end, it is particularly possible for the channel bottom 16 of the channels 15 to have a slight inclination down to the tundish outlet region 8.

[0052] The channels 15 are thus delimited on the one hand by their channel bottom 16 and on the other by a side wall 4, 5 and a channel wall 17 of the threshold 12 or ramp 12.

[0053] In this case, the channels 15 can also be spaced somewhat apart from the side walls 4, 5 so that the threshold 12 is not perforated at the edges, but is instead the perforation is shifted a short distance toward the longitudinal axis 9.

[0054] With a conventional tundish geometry, the channel 15 or channels 15 has/have a width, for example, of 70 mm to 80 mm and a height that corresponds to the height of the threshold 12; it turns out to be advantageous if the walls 4, 5, or 7 adjoining the channels 15 get wider as they extend away from the channel bottom 16, for example with an angle of 10° to 20° (FIG. 6 and FIG. 7).

[0055] In flow simulations (FIG. 8 and FIG. 9), it has turned out that in comparison to the prior art (FIG. 8), because of the lateral channels (FIG. 9), with the continuous filling of the tundish, in both cases, a distinct back flow is produced along the inclined bottom and along the threshold 12 or ramp 12 and the channel or channels 15 provided do not hinder this back flow and also do not negatively affect the holding time of the particles and the particle flow in the tundish.

[0056] Instead, it has been demonstrated that despite or because of the lateral channels, there is a surprising further improvement of the holding time (FIG. 5).

[0057] The threshold 12 or ramp 12 can be positioned perpendicular to the longitudinal axis 9 of the tundish 1; it can also extend in a rounded or curved fashion.

[0058] The threshold 12 has a height that is lower than the maximum bath surface 10 during operation of the tundish 1 in order not to negatively influence the particle flow.

[0059] Preferably, the threshold 12 has a height whose ratio relative to the bath surface 10 is less than 1:5, preferably less than 1:10.

[0060] The invention has the advantage that the channel or channels 15 provided surprisingly do(es) not negatively affect the particle removal behavior, but rather improve(s) it; in addition, a residual emptying of the cup is enabled, which makes it possible to work in a significantly more economical way.