EP1206986B1 - Continuous casting mould, especially for casting billet strands and blooms - Google Patents

Abstract

A continuous casting mold comprise a casting tube (1) surrounded by a mold housing with a gap (3) into which a cooling medium stream (4) can be introduced and removed. The gap varies over the height of the mold so that it is narrow in the upper part of the mold and corresponds to a high cooling medium speed and it is relatively wide in the lower region of the mold corresponding to a relatively low cooling medium speed. Preferred Features: The contour of the outer cooling medium gap wall (5a) corresponds to the negative mold of the solidification line in the casting strand running from above to below.

Description

The invention relates to a continuous casting mold, in particular for casting billets or billet strands, the pouring tube is surrounded by a mold housing with gap spacing, in which a cooling medium flow can be supplied and discharged again, wherein the cooling medium gap is so different over the mold height that in the upper die area the cooling medium gap is narrow in accordance with a high cooling medium speed and relatively wide in the lower die area, corresponding to a relatively lower cooling medium speed,

(s = Strangschalendicke; k = Abkühlungsfaktor; t = Zeit).
Um die sich daraus ergebende Erstarrungskurve schon in der Stranggießkokille zu berücksichtigen, kann in der Stranggießkokille die Regulierung der Wärmeabfuhr über örtlich abgestimmte Wassergeschwindigkeiten erfolgen. Im Meniskus des Kokillen-Badspiegels muss ein Maximum an Wärme abgeführt werden, während am Austritt der Stranggießkokille eine entsprechend geringere Wärmemenge abzuführen ist.In the continuous casting of metals, in particular of steel, the liquid steel solidifies in the course of the casting process from outside to inside in the continuous casting mold. The solidification is approximately hyperbolic according to the equation $$\mathrm{s}=\mathrm{k}\times \mathrm{V}\mathrm{t}$$

(s = strand shell thickness, k = cooling factor, t = time).
In order to take the resulting solidification curve into account already in the continuous casting mold, the regulation of the heat removal via spatially coordinated water velocities can take place in the continuous casting mold. In the meniscus of the mold bath mirror, a maximum of heat must be dissipated, while at the outlet of the continuous casting mold a correspondingly smaller amount of heat has to be dissipated.

From DE-OS 14 83 556 a cooling zones division is provided on the mold height, each of the superimposed cooling zones is assigned its own supply and discharge line.

From DE-AS 1 608 059 it is known to direct the cooling medium in vertical channels from bottom to top through the cooling box of the mold and build up a high back pressure.

From JP-A-03 042 144 and JP-A-59 070 442 it is known to give the mold housing (cooling water jacket) such a contour that the cooling medium in the upper part around the mold by a narrower gap faster and in the lower part flows slower through another gap.

The invention has for its object to control the speed of the cooling medium in the cooling passage of the cooling jacket of a continuous casting mold of the type mentioned above the geometry of the Kühlmediumleitmantels even more precisely.

The stated object is achieved in that the cooling medium gap is additionally increased in corner areas and that the cooling medium gap over the Kokillenbreitseiten and / or the Kokillenlängsseiten is different widths, wherein the narrow gap is provided in each case in the middle of the page. As a result, regulation of the water velocities and thus of the heat dissipation can be achieved by means of this geometric design of the coolant media channels. Since the corners of the cast strand require less heat dissipation compared to the surfaces, the cooling medium speed can be reduced somewhat here. As a result, a greater cooling medium speed is achieved in the side centers through the narrow gaps, and a lower speed is achieved at the corners by the bulges.

In this case, at least the vertical contour of the outer cooling medium gap wall corresponds to a negative form of the solidification line in the casting strand which runs from top to bottom. This negative mold leads to small cooling medium velocities in the lower mold area and through the narrow gap to high cooling medium velocities in the upper mold area.
For the production, it is advantageous that the pouring tube is cylindrical and the mold housing (the Wasserleitmantel) has the vertical contour.

A favorable flow with a small flow resistance also arises from the fact that the corner regions of a horizontal contour are each formed bulging in an oval shape.

In the drawing, an embodiment of the invention is shown schematically and will be explained in more detail below.

Fig. 1

einen senkrechten Schnitt durch die Stranggießkokille und

Fig. 2

einen horizontalen Schnitt gemäß der Schnittangabe A-A in Fig. 1.

Show it:

Fig. 1

a vertical section through the continuous casting mold and

Fig. 2

a horizontal section according to the section AA in Fig. 1st

The continuous casting mold is used in particular for casting billet or billet strands and is provided with a pouring pipe 1 and a mold housing 2, which forms a Wasserleitmantel 2a. The mold housing 2 is located with gap distance 3 to the pouring pipe 1. The cooling medium 4, as usual water or water with additives, is fed into the cooling medium gap 5 on the mold height 6 in the lower mold area 6b and under heating when rising in the upper mold area 6a again discharged in the direction of the arrow after heat absorption.

The cooling medium gap 5 is of different widths over the mold height 6 in that the cooling medium gap 5 is narrow in the upper mold region 6a, corresponding to a high cooling medium velocity, and relatively wide in the lower mold region 6b, corresponding to a relatively lower cooling medium velocity , The flow velocity of the cooling medium 4 depends on the negative shape of the solidification line in the cast strand, after which at least the vertical contour 7 of the outer cooling medium gap wall 5a is fixed (FIG. 1).

Corresponding to the section A-A in the horizontal (FIG. 2), the cooling medium gap 5 in the corner regions 8 is additionally enlarged. The cooling medium gap 5 is different in width according to the basic idea about the chill broad side 9 and / or the Kokillenlängsseite 10, wherein the narrow gap 11 is in each case in the side center 12.

The production of the pouring tube 1 is simple and can be performed very accurate form, since the pouring tube 1 is formed by itself cylindrically and the mold housing 2 has the vertical contour 7 (Fig. 1). The same property results in the horizontal section (FIG. 2) when the corner regions 8 of a horizontal contour 13 are each bulged in an oval shape.

The respective gap width follows the function gap = f (h) according to FIG. 1 and the function gap = f (x) according to FIG. 2.

LIST OF REFERENCE NUMBERS

1

casting tube

2

mold housing

2a

Wasserleitmantel

3

gap distance

4

cooling medium

5

Cooling medium gap

5a

Cooling medium Spaltwandung

6

mold height

6a

upper mold area

6b

lower mold area

7

vertical contour

8th

corner area

9

mold broad

10

Kokillenlängsseite

11

narrow gap

12

page center

13

horizontal contour

Claims (4)

1. Continuous casting mould, particularly for casting billet or bloom strips, the pouring pipe (1) of which is surrounded by a mould housing (2) with a gap spacing (3), into which a coolant flow (4) can be fed and discharged again, wherein the coolant gap (5) is of differing width over the mould height (6) in such a manner that in the upper mould region (6a) the coolant gap (5) is narrow in correspondence with a high coolant speed and in the lower mould region (6b) is relatively wide in correspondence with a relatively low coolant speed, characterised in that the coolant gap (5) in corner regions (8) is additionally enlarged and that the coolant gap (5) over the mould wide sides (9) and/or the mould longitudinal sides (10) is of differing width, wherein the narrow gap (11) is respectively provided in the side centre (12).
2. Continuous casting mould according to claim 1, characterised in that at least the vertical contour (7) of the outermost coolant gap wall (5a) corresponds with a negative form of the hardening line in the casting strip, which extends from above to below.
3. Continuous casting mould according to one of claims 1 and 2, characterised in that the pouring pipe (1) is formed to be cylindrical and the mould housing (2) has the vertical contour (7).
4. Continuous casting mould according to one of claims 1 to 3, characterised in that the corner regions (8) of a horizontal contour (13) are each formed to bulge out in oval shape.

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