EP0834364B1 - Method and device for high-speed continuous casting plants with reduction of the width during solidification - Google Patents

Abstract

Continuous casting process has strand cross-section reduction during strand solidification. The strand is cast in an oscillating mould and subjected to a linear cross-section reduction over a minimum length of the strand guide immediately below the mould, followed by a further "soft reduction" over the remaining strand guide up to a point close to full strand solidification. A corresponding casting plant is also claimed.

Description

The invention relates to a method and an apparatus for Continuous caster for the production of strands, their cross section is reduced during solidification.

It is known that the strands are on high speed equipment generally with a solidification thickness between 18 and 450 mm and casting speeds up to a maximum of 12 m / min e.g. on plants for casting slabs, blooms and sticks with a square or round profile, one of which Reduction of the strand cross-section, preferably in the thickness direction made after it emerged from the mold during solidification becomes.

This technology of casting rolling thin slabs or round billets is by the patents DE 44 03 048 and DE 44 03 049 or DE 41 39 242 become known; in the case of thin slabs they are also used daily in production facilities.

So z. B. a thin slab with a thickness of, for example, 65 to 40 mm in segment 0, which is located directly under the mold, reduced. This strand thickness reduction by 25 mm or 38.5% can qualitatively disadvantageous for certain steel grades sensitive to internal cracks his. The inner strand deformation can be caused by the Strand thickness reduction or also called casting rolls, for the trigger of internal cracks because of the critical deformation of the material liquid / solid on the inner strand shell, but also on the outer Strand shell is exceeded.

This example is based on a 2 m long circular arc segment 0, which is none Introduces bending work or bending deformation into the strand shell. The forming speed the strand shell during casting rolling during solidification, the one The measure for the strand deformation is 1.25 mm / s with a casting speed of 6 m / min. This value of the forming speed increases with a Casting speed increase to z. B. 10 m / min to 2.08 mm / s, where he becomes very critical. Such internal deformations caused solely by casting rolling are not just for the low-carbon steel grades that are relatively insensitive against internal deformations, but especially for sensitive steels such as micro-alloyed APX-80 grades critical.

The deformation caused by the casting rolling can also with Vertical turning systems, usually in the segment under the mold at the same time there is a bending of the strand, still by the in the strand greatly increase the bending deformation, which increases the risk of exceeding it the critical deformation and thus the crack formation is further increased becomes.

The above-mentioned knowledge and connections are forward-looking the invention has the object of procedural measures and simple device features the rate of deformation of the Specify strand cross-section reduction so that the critical deformation of the Stranges taking into account the casting speed and also the steel grade is not exceeded.

The object is achieved according to the invention with a method for Continuous casting to produce strands, the cross section of which during solidification is reduced in such a way that in a particularly oscillating mold is poured and the strand cross section linear over a minimum length of Strand guidance immediately below the mold, the so-called casting rolls, is reduced and there is a further non-linear reduction in the cross-section of the strand, for example after the square-root function, the so-called "soft reduction", over the rest of the strand guide up to a maximum of just before the swamp tip. The features of the invention apply to all formats cast in the strand and also for all types of continuous casting plants and describe with the method to claim 1 and its subclaims as well as the device claim and its subclaims the invention.

The following unexpected solution according to the invention to achieve the above The goal described is based on the example of a thin slab explained in more detail, the invention in particular for casting of thin slabs with a thickness between 60 and 120 mm after the Solidification, the thickness of the slab in the edge area at Mold exit z. B. is a minimum of 70 and a maximum of 160 mm is pulled. The reduction in strand thickness, normally between the top and bottom of a strand guide takes place, is according to the state of the art today under test conditions maximum 60%, here is a 50 mm thick slab reduced to approx. 20 mm over a roll gap length of approx. 200 mm, and under production conditions a maximum of 38.5%, here the Strand from 65 to 40 mm over the length of segment 0 of approx. 2 m, which is located below the mold, reduced. In both Cases there is a maximum pouring speed of 6 m / min.

The description of the invention is based on an example Thin slab with a thickness of 100 mm at the mold outlet and a thickness of 80 mm after solidification. The invention now proposes one Type of distribution and implementation of strand thickness reduction during the solidification of the thin slab in the strand guide frame for the exemplary casting speeds of 6 and 10 m / min before.

Tables 1 and 1.1 are the essential process and device data contrasted the invention with the prior art. Table 1 provides the data for casting speeds of 6 m / min and Table 1.1 for speeds of 10 m / min represents.

In both tables, the total reduction in the thickness of the strand of 20 mm during solidification in its distribution between segment 0 and the rest of the strand guide, segments 1 to maximum 13, varies. The state of the art is in the Tables by a total reduction of the strand thickness of 20 mm, carried out in segment 0 alone (see paragraphs 19 to 22 in column 1). Here it becomes clear that the rate of reduction of the strand in the 3 m segment 0, triggered by the Strand thickness reduction or casting rolling, and therefore functional the strand shell deformation from 0.67 to 1.11 mm / s at one Increased casting speed from 6 m / min to 10 m / min.

• 15 mm im Segment 0 und 5 mm in den Segmenten 1 - n, Ziffern 19-28, Spalte 2;
• 10 mm im Segment 0 und 10 mm in den Segmenten 1 - n, Ziffern 19-28, Spalte 3;
• 5 mm im Segment 0 und 15 mm in den Segmenten 1 - n, Ziffern 19-28, Spalte 4;
• 20 mm in den Segmenten 0 bis n, Ziffern 29 - 34.

Numbers 19-22 and 23-28, columns 2, 3 and 4 and numbers 29-34 now represent the solution according to the invention, which greatly reduces the rate of deformation of the strand shell by redistributing the total thickness reduction of 20 mm between segment 0 and segments 1 - n, which can also be referred to as "soft reduction". This redistribution is explained in more detail using the following examples:

• 15 mm in segment 0 and 5 mm in segments 1 - n, numbers 19-28, column 2;
• 10 mm in segment 0 and 10 mm in segments 1 - n, numbers 19-28, column 3;
• 5 mm in segment 0 and 15 mm in segments 1 - n, numbers 19-28, column 4;
• 20 mm in the segments 0 to n, numbers 29 - 34.

• 1,11 mm/s, 20 mm im Segment 0, Stand der Technik, Ziffer 21, Spalte 1 auf
• 0,114 mm/s, 20 mm in den Segmenten 0 bis 13, Ziffer 33

abgesenkt werden. Mit Verlagerung eines Teiles der Dickenreduktion vom Segment 0 in die Segmente 1 bis 13 oder 1 bis n - je nach Gießgeschwindigkeit - wird allerdings die einzubringende Arbeit in den Strang mit wachsender Strangschalendicke größer. Die Erfindung berücksichtigt daher, daß eine optimale Verteilung der Gesamt-Dickenreduktion in der gesamten Strangführung zwischen dem Segment 0 und dem Segment n, das bis unmittelbar vor der Enderstarrung reicht, die Strangschalendicke auch mit einbezieht. Diese Berücksichtigung wird durch eine Quadrat-Wurzel Funktion über die Erstarrungszeit in vorteilhafter Weise entweder im Bereich der Segmente 1 bis n , soft reduction, oder im Bereich der Segmente 0 bis n, soft reduction, erreicht.So the reduction speed and thus the functional deformation speed of the strand shell with 20 mm total thickness reduction and 10 m / min casting speed of

• 1.11 mm / s, 20 mm in segment 0, state of the art, number 21, column 1
• 0.114 mm / s, 20 mm in segments 0 to 13, number 33

be lowered. With a shift in part of the thickness reduction from segment 0 to segments 1 to 13 or 1 to n - depending on the casting speed - the work to be introduced into the strand increases with increasing strand shell thickness. The invention therefore takes into account that an optimal distribution of the total thickness reduction in the entire strand guide between segment 0 and segment n, which extends until just before final solidification, also includes the strand shell thickness. This consideration is advantageously achieved by a square-root function over the solidification time either in the range of segments 1 to n, soft reduction, or in the range of segments 0 to n, soft reduction.

Figures 1 to 7 illustrate the invention in detail in comparison the state of the art.

• der Überhitzungsphase (1), der reinen Schmelzphase oder auch Penetrationszone genannt mit ihrem tiefsten Liquiduspunkt (1.1),
• dem 2-Phasengebiet, Schmelze/Kristall (2) mit seinem tiefsten Soliduspunkt, der Sumpfspitze (2.1) nach 30 m Strangführung, die aus einer ca. 1,2 m langen Kokille, einem 3 m langem Segment 0 und den Segmenten 1 bis 13 mit einer Länge von insgesamt 26 m besteht und
• der festen Phase oder Strangschale (3).

Figure 1 with pictures 1 and 2 shows schematically the situation of a strand with a thickness in the mold of 100 mm and a solidification thickness of 80 mm for a casting speed of 10 m / min and a total strand thickness reduction of 20 mm only in segment 0 , Casting rolls, (Figure 1) or 10 mm in segment 0, casting rolls, and 10 mm in segments 1 to 13, "soft reduction", (Figure 2). Furthermore, the strand is shown in the machine with its steel phases, how

• the overheating phase (1), the pure melting phase or also called the penetration zone with its lowest liquidus point (1.1),
• the 2-phase area, melt / crystal (2) with its deepest solidus point, the swamp tip (2.1) after 30 m strand guidance, which consists of an approx. 1.2 m long mold, a 3 m long segment 0 and segments 1 to 13 with a total length of 26 m and
• the solid phase or strand shell (3).

The pure melting phase or penetration zone is in the range of segment 0, in which a strand thickness reduction or casting rolling of 2 x 10 mm or 20 mm and no more in the following segments 1 to 13, - Description of the state of the art (Image 1) -, or of 2 x 5 mm or 10 mm, casting rolls, and another 10 mm in the following segments 1 to 13, "soft reduction", part of the invention (Photo 2). The reduction in strand thickness in the segment 0, the z. B. as pliers segment with two clamping devices, e.g. B. hydraulic cylinders (14) (Fig. 6), formed at the segment exit is linear over a length of 3 m; the reduction in the area of segments 1 - 13, but also across all segments, both linear and non-linear, i.e. for example following a square root. In the picture 2 is the strand thickness reduction of 10 mm in the segments 1-13, "soft reduction" - linear distribution.

• Stand der Technik, Bild 1 :
• Segment 0, Reduktion 20 mm, Gießwalzen, Reduktionsgeschwindigkeit 1,11 mm/s;
• Segmente 1-13, Reduktion 0 mm, kein "soft reduction", Reduktionsgeschwindigkeit 0
• Erfindung, Bild 2 :
• Segment 0, Reduktion 10 mm, Gießwalzen, Reduktionsgeschwindigkeit 0,56 mm/s;
• Segmente 1-13, Reduktion 10 mm, soft reduction, Reduktionsgeschwindigkeit 0,064 mm/s.

The reduction speed in mm / s of the strand shell, which is a measure of the strand shell deformation, can be significantly reduced in the case of the invention (Figure 2) compared to the prior art (Figure 1), as the following values show:

• State of the art, Figure 1:
• Segment 0, reduction 20 mm, casting rolls, reduction speed 1.11 mm / s;
• Segments 1-13, reduction 0 mm, no "soft reduction", reduction speed 0
• Invention, Figure 2:
• Segment 0, reduction 10 mm, casting rolls, reduction speed 0.56 mm / s;
• Segments 1-13, reduction 10 mm, soft reduction, reduction speed 0.064 mm / s.

The distribution of strand thickness reductions between segment 0 and the following segments 1 - 13 can now be optimal, with regard to the possible strand deformation while avoiding internal and surface cracks and the minimal work to be done to reduce the strand thickness, that grows with the thickness of the strand shell, to get voted.

• 1,168 mm/m Strangführung (RL-6) und 0,117 mm/s (RS-6) bei 6 m/min Gießgeschwindigkeit bzw.
• 0,685 mm/m Strangführung (RL-10) und 0,114 mm/s (RS-10) bei 10/min Gießgeschwindigkeit

ein, die die geringste Deformationsgeschwindigkeit aufweisen, allerdings einen maximalen Aufwand an Arbeit verlangen und einen "soft reduction" Vorgang über die gesamte Strangführung ergeben. Zwischen diesem Extrem, der Gesamtreduktion von 20 mm im Segment 0 und der Reduktion gleichförmig über die Strangführung im Segment 0 bis kurz hinter der Enderstarrung des Stranges verteilt, setzt die Erfindung mit ihren Ansprüchen an.This distribution effect on the reduction speed and thus on the strand shell loading is given in Tables 1 and 1.1 and shown in FIGS. 2 and 3. FIG. 2 shows the reduction of the strand thickness in mm / m strand guidance for a total thickness decrease of 20 mm depending on different decreases in segment 0 and the corresponding complementary thickness decrease in segments 1-13 for the continuous casting speeds of 6 and 10 m / min. With a linear distribution of the total reduction of 20 mm over all segments 0 to 8 or 13, values for the thickness reduction (RL-6) and (RL-10) and reduction speed (RS-6) and (RS-10) of

• 1.168 mm / m strand guide (RL-6) and 0.117 mm / s (RS-6) at 6 m / min casting speed or
• 0.685 mm / m strand guide (RL-10) and 0.114 mm / s (RS-10) at 10 / min casting speed

a, which have the lowest rate of deformation, but require maximum effort and result in a "soft reduction" process over the entire strand. Between this extreme, the total reduction of 20 mm in segment 0 and the reduction uniformly distributed over the strand guide in segment 0 to just behind the final solidification of the strand, the invention starts with its claims.

Like FIG. 1, FIG. 4 schematically represents the situation of a Strands with a thickness in the mold of 100 mm and a solidification thickness of 80 mm for the casting speeds VG of 6 m / min, Figure 3, and of 10 m / min, Figure 4 compared. in the According to the invention, the strand thickness reduction is 6 m / min from Z. B. 10 mm in segment 0 and of the remaining 10 mm in the Segments 1 to 8, corresponding to the shorter solidification path, performed. So the lowest liquidus point (1.2) is at already about 1.8 m and the swamp tip (2.2) at about 18.12 m. There the reduction in the strand thickness is a maximum of 18.12 m and At the same time the final solidification is to be included, the segments 1 to 8 used for the reduction of the thickness. The picture 4 in Figure 4 shows the situation of the strand like Figure 2 in Figure 1 at a casting speed of VG 10 m / min.

• 6 m/min, Bild 3 in Figur 4, Erfindungsbeispiel,
• Segment 0, Reduktion 10 mm, Reduktionsgeschwindigkeit 0,33 mm/s, Gießwalzen;
• Segmente 1 - 8, Reduktion 10 mm, Reduktionsgeschwindigkeit 0,071 mm/s, soft reduction,
• 10 m/min Bild 4 in Figur 4, Erfindungsbeispiel,
• Segment 0, Reduktion 10 mm, Reduktionsgeschwindigkeit 0,56 mm/s, Gießwalzen;
• Segmente 1 -13, Reduktion 10 mm, Reduktionsgeschwindigkeit 0,064 mm/s, soft reduction.

The comparison of the casting situations according to the invention, shown in FIGS. 3 and 4 in FIG. 4, leads to the following values of the reduction speeds and thus strand shell loads:

• 6 m / min, Figure 3 in Figure 4, example of the invention,
• Segment 0, reduction 10 mm, reduction speed 0.33 mm / s, casting rolls;
• Segments 1 - 8, reduction 10 mm, reduction speed 0.071 mm / s, soft reduction,
• 10 m / min Figure 4 in Figure 4, inventive example,
• Segment 0, reduction 10 mm, reduction speed 0.56 mm / s, casting rolls;
• Segments 1-13, reduction 10 mm, reduction speed 0.064 mm / s, soft reduction.

This comparison makes it clear that the distribution of the thickness reduction is also a question of casting speed and that, accordingly the location of the swamp tip, d. H. the casting speed, the thickness reduction and its distribution in the segments 1 to n or 0 to n an optimal pouring situation with regard to pouring safety and is to be adapted to the strand quality.

5 shows the effect of a distribution of the strand thickness reduction in segment 0 and in segments 1 to 13 in the sense of Invention (Figure 6) using the example of a vertical bending machine, FIG. 6, compared to the prior art (FIG. 5), on the inner strand deformation, caused by the bending deformations and the strand thickness reduction, depending on the strand guide for the maximum casting speed of, for example, 10 m / min shown.

Figure 5 represents the state of the art in Figure 5 the inner strand deformation depending on the strand guidance for the maximum casting speed (Vg-10) of 10, for example m / min compared to the boundary deformation (D-Gr). At the exit of the The mold in segment 0 undergoes both a deformation, caused by the casting rolling (D-Gw) in segment 0, as well a deformation caused by the bending process (D-B). Both Deformations overlap to the total deformation (D-Ge), the becomes larger than the limit deformation (D-Gr) and therefore critical becomes. Exceeding the boundary deformation leads to internal cracks solid / liquid at the phase boundary and thus to reduce quality of the strand and to reduce casting reliability. Another The strand experiences increased internal deformation (D) through the Deformation (D-R) when it bends back in segment 4 from the inner circular arc into the horizontal, which, however, is not critical can be because the number of bending points in the "design" the system is chosen so that the reverse bending process at maximum No critical internal deformation in the casting speed Strand shell of the most crack-sensitive steel grade can trigger.

Figure 6 in Figure 5 shows the procedural features the invention using the example of a vertical turning system, Figure 6, schematically. The inner deformation (D) of the strand shell (3) is never in a moment of solidification, H. from the mold exit critical to the end of scaffold 13. This is due to the distribution the total strand thickness reduction from 20 mm to, for example 10 mm in segment 0 (D-Gw) and 10 mm in frames 1 to 13 (D-SR) ensured according to the invention. In addition, the bending process and the associated deformation (D-B) from segment 0 in segment 1 placed around the lowered but still relatively high Deformation density (D-Gw) in segment 0, caused by the Casting rolls of 10 mm, for example, not to be increased additionally. The deformation generated in segments 1 to 13 (D-SR), caused by the "soft reduction" of a total of z. B. 10 mm, is relatively small and does not lead to a practical increase in the Deformation (D-R) when the strand is bent back in segment 4, d. H. (D-Ge) is approximately greater than or equal to (D-R).

• einer ca. 1,2 m langen Senkrecht -Kokille (K), die vorzugsweise in horizontaler Richtung konkav ausgebildet ist,
• einem 3 m langem Segment 0, das für das Gießwalzen oder auch die Strangdickenreduktion vorzugsweise als Zangensegment ausgerüstet und mit zwei hydraulischen Zylindern (14) an seinem Ausgang versehen ist,
• dem Segment 1 mit fünf Biegepunkten (23),
• den Segmenten 2 und 3 mit dem inneren Kreisbogen von ca. 4 m Radius,
• dem Segment 4 zum Rückbiegen des Stranges vom inneren Kreisbogen über fünf Rückbiegepunkte (24) in die Horizontale und
• den Segmenten 5 bis13 im horizontalen Bereich der Maschine.

FIG. 6 shows a vertical bending system, to which the invention can be applied by way of example, for the casting of 100 mm thick slabs at the mold exit with a thickness after solidification of 80 mm and a maximum of 10 m / min. This system has the procedural features described in FIGS. 1-5. The continuous casting plant consists of a distributor (V) and a dip spout (Ta)

• an approximately 1.2 m long vertical mold (K), which is preferably concave in the horizontal direction,
• a 3 m long segment 0, which is preferably equipped as a tong segment for the casting rolling or the strand thickness reduction and is provided with two hydraulic cylinders (14) at its outlet,
• segment 1 with five bending points (23),
• segments 2 and 3 with the inner circular arc of approx. 4 m radius,
• the segment 4 for bending back the strand from the inner circular arc via five bending points (24) into the horizontal and
• segments 5 to 13 in the horizontal area of the machine.

This machine configuration with a maximum casting speed of 10 m / min and a maximum capacity of approx. 3 million t / a represents an extremely advantageous solution when using the Invention represents, in which a minimal rate of deformation of the strand occurs during its solidification.

To the type of strand thickness reduction in the sense of the invention with to advantageously implement the segments 1 to 13 described should, in principle, the segments as shown in Figure 7 be constructed. A segment should preferably be an odd one Number of 3, 5, 7 or 9 pairs of rollers (15) consisting of Lower (16) and upper roller (17) can be built. Every segment alternately consists of a pair of driven rollers (18), which is position and force controlled with a hydraulic system (19) and two with a hydraulic system (20) in the area the top rollers (17) connected non-driven roller pairs (21), which are provided with a machine element (22) that it allowed the pair of rollers of the top web in the casting direction by one Angle of z. B. to allow +/- 5 ° to swing in any casting situation for a given decrease in strand thickness, the strand if secured its shape.

This structure of segments 1 to 13 leads to an optimal one Strand guidance in any type of distribution of strand thickness reduction, every casting situation, every kind of steel grade, with regard to their internal crack sensitivity, d. H. Critical Deformation Limit and the use of a minimum of hydraulic Systems per pair of rollers. So come 0.66 hydraulic systems per pair of rollers. The use of driven Roll pairs of 0.33 units per roll pair a mechanical engineering Minimum at maximum procedural and qualitative effect on the strand to be cast and its surface and interior quality, d. H. for example a minimal one Structure and a minimized accumulation of tensile stresses in the Strand shell between the driven roller pairs.

• Brammenanlagen,
• Vorblockanlagen,
• Knüppelanlagen für Quadrat- und Rund-Knüppel. Gießgeschwindigkeit 6 m/min Spalte 1 2 3 4 5 1 Strangdicke mm 100 2 Erstarrungsdicke mm 80 3 met. Länge der Kokille m 1 4 Länge des Segmentes 0 m 3 5 Länge der Segmente 1 - 13 m 26 6 Länge der ges. Strangführung m 30 7 Erstarrungszeit min 3,02 8 Erstarrungszeit s 181,2 9 Gießgeschwindigkeit m/min 6,0 10 metallurgische Länge des Stranges m 18,12 11 Erstarrungszeit, Eintritt Segm. 0 min 0,167 12 Erstarrungszeit, Eintritt Segm. 0 s 10,0 13 Strangschalendicke, Eintritt Segm. 0 mm 9,4 14 Verweilzeit des Stranges in Segm, 0 min 0,5 15 Verweilzeit des Stranges in Segm. 0 s 30,0 16 Erstarrungszeit, Austritt Segm. 0 min 0,667 17 Erstarrungszeit, Austritt Segm. 0 s 40,02 18 Strangschalendicke, Austritt Segm, 0 mm 18,78 19 Dickenreduktion in Segment 0 mm 20 15 10 5 0 20 Dickenreduktion in Segment 0 % 20 15 10 5 0 21 Reduktionsgeschwindigkeit mm/s 0,67 0,5 0,33 0,17 0 22 Reduktion / Meter Strangführung mm/m 6,67 5,0 3,33 1,67 0 23 Soft reduction in Segment 1-n(8) mm 0 5 10 15 20 24 Zeit für restliche Erstarrung min 2,353 25 Zeit für restliche Erstarrung s 141,18 26 Soft reduction-Geschwindigkeit mm/s 0 0,035 0,071 0,106 0,14 27 metallurgische Länge der Rest-Erstarrung m 14,12 28 Soft reduction/Meter Rest-Erstarrung mm/m 0 0,35 0,71 1,062 1,42 29 Soft reduction, Segment 0 - n (8) mm 20 30 Zeit der Erstarrung in den Segm. 0 - n min 2,853 31 Zeit der Erstarrung in den Segm. 0 - n s 171,18 32 metallurgische Länge, Segm. 0 - n m 17,12 33 Soft reduction - Geschw., Segm. 0 - n mm/s 0,117 34Soft reduction/Meter Erstarrung, Segm.0-n mm/m 1,168 Gießgeschwindigkeit 10 m/min Spalte 1 2 3 4 5 1 Strangdicke mm 100 2 Erstarrungsdicke mm 80 3 met. Länge der Kokille m 1 4 Länge des Segmentes 0 m 3 5 Länge der Segmente 1 - 13 m 20 6 Länge der ges. Strangführung m 30 7 Erstarrungszeit min 3,02 8 Erstarrungszeit s 181,2 9 Gießgeschwindigkeit m/min 10,0 10 metallurgische Länge des Stranges m 30,20 11 Erstarrungszeit, Eintritt Segm. 0 min 0,10 12 Erstarrungszeit, Eintritt Segm.0 s 6,0 13 Strangschalendicke, Eintritt Segm. 0 mm 7,3 14 Verweilzeit des Stranges in Segm. 0 min 0,3 15 Verweilzeit des Stranges in Segm 0 s 18,0 16 Erstarrungszeit, Austritt Segm. 0 min 0,4 17 Erstarrungszeit, Austritt Segm. 0 s 24,0 18 Strangschalendicke, Austritt Segm. 0 mm 14,55 19 Dickenreduktion in Segment 0 mm 20 15 10 5 0 20 Dickenreduktion in Segment 0 % 20 15 10 5 0 21 Reduktionsgeschwindigkeit mm/s 1,11 0,83 0,56 0,28 0 22 Reduktion / Meter Strangführung mm/m 6,67 5,0 3,33 1,67 0 23 Soft reduction in Segment 1 - n (13) mm 0 5 10 15 20 24 Zeit für restliche Erstarrung min 2,62 25 Zeit für restliche Erstarrung s 157,2 26 Soft reduction - Geschwindigkeit mm/s 0 0,032 0,064 0,095 0,127 27 metallurgische Länge der Rest-Erstarrung m 26,2 28 Soft reduction / Meter Rest-Erstarrung mm/m 0 0,19 0,38 0,57 0,76 29 Soft reduction, Segment 0 - n (13) mm 20,0 30 Zeit der Erstarrung in den Segm. 0 -n min 2,92 31 Zeit der Erstarrung in den Segm. 0 - n s 175,2 32 metallurgische Länge, Segm. 0 - n m 29,2 33 Soft reduction - Geschw., Segm. 0 - n mm/s 0,114 34Soft reduction/Meter Erstarrung, Segm.0-n mm/m 0,685

The invention has been described using the example of a thin slab plant, but can also be transferred accordingly to other continuous casting plants with regard to the method and the device, such as

• Slab lines,
• Blooming lines,
• Billet lines for square and round billets. Casting speed 6 m / min column 1 2 3rd 4th 5 1 strand thickness mm 100 2 solidification thickness mm 80 3 met. Length of the mold m 1 4 Length of segment 0 m 3rd 5 Length of segments 1 - 13 m 26 6 total length Strand guide m 30th 7 solidification time min 3.02 8 solidification time s 181.2 9 casting speed m / min 6.0 10 metallurgical length of the strand m 18.12 11 Freezing time, entry Segm. 0 min 0.167 12 Freezing time, entry Segm. 0 s 10.0 13 strand shell thickness, entry Segm. 0 mm 9.4 14 Dwell time of the strand in Segm, 0 min 0.5 15 Dwell time of the strand in Segm. 0 s 30.0 16 Freezing time, segm. 0 min 0.667 17 Freezing time, exit segm. 0 s 40.02 18 strand shell thickness, outlet Segm, 0 mm 18.78 19 Thickness reduction in segment 0 mm 20th 15 10 5 0 20 Thickness reduction in segment 0 % 20th 15 10 5 0 21 reduction speed mm / s 0.67 0.5 0.33 0.17 0 22 Reduction / meter strand guidance mm / m 6.67 5.0 3.33 1.67 0 23 Soft reduction in segment 1-n (8) mm 0 5 10 15 20th 24 time for remaining solidification min 2,353 25 time for remaining solidification s 141.18 26 Soft reduction speed mm / s 0 0.035 0.071 0.106 0.14 27 Metallurgical length of the remaining solidification m 14.12 28 Soft reduction / meter solidification mm / m 0 0.35 0.71 1,062 1.42 29 Soft reduction, segment 0 - n (8) mm 20th 30 time of solidification in the segm. 0 - n min 2,853 31 Time of solidification in the segm. 0 - n s 171.18 32 metallurgical length, segm. 0 - n m 17.12 33 Soft reduction - speed, segm. 0 - n mm / s 0.117 34 Soft reduction / meter solidification, segment 0-n mm / m 1,168 Casting speed 10 m / min column 1 2 3rd 4th 5 1 strand thickness mm 100 2 solidification thickness mm 80 3 met. Length of the mold m 1 4 Length of segment 0 m 3rd 5 Length of segments 1 - 13 m 20th 6 total length Strand guide m 30th 7 solidification time min 3.02 8 solidification time s 181.2 9 casting speed m / min 10.0 10 metallurgical length of the strand m 30.20 11 Freezing time, entry Segm. 0 min 0.10 12 Freezing time, entry Segm. 0 s 6.0 13 strand shell thickness, entry Segm. 0 mm 7.3 14 Dwell time of the strand in Segm. 0 min 0.3 15 Dwell time of the strand in Segm 0 s 18.0 16 Freezing time, segm. 0 min 0.4 17 Freezing time, exit segm. 0 s 24.0 18 strand shell thickness, outlet Segm. 0 mm 14.55 19 Thickness reduction in segment 0 mm 20th 15 10 5 0 20 Thickness reduction in segment 0 % 20th 15 10 5 0 21 reduction speed mm / s 1.11 0.83 0.56 0.28 0 22 Reduction / meter strand guidance mm / m 6.67 5.0 3.33 1.67 0 23 Soft reduction in segment 1 - n (13) mm 0 5 10 15 20th 24 time for remaining solidification min 2.62 25 time for remaining solidification s 157.2 26 Soft reduction - speed mm / s 0 0.032 0.064 0.095 0.127 27 Metallurgical length of the remaining solidification m 26.2 28 Soft reduction / meter solidification mm / m 0 0.19 0.38 0.57 0.76 29 Soft reduction, segment 0 - n (13) mm 20.0 30 time of solidification in the segm. 0 -n min 2.92 31 Time of solidification in the segm. 0 - n s 175.2 32 metallurgical length, segm. 0 - n m 29.2 33 Soft reduction - speed, segm. 0 - n mm / s 0.114 34 Soft reduction / meter solidification, segment 0-n mm / m 0.685

Reference list

1.

Overheating phase, pure melting phase or penetration zone,

1.1

lowest liquidus point at 10 m / min casting speed,

1.2

lowest liquidus point at 6 m / min casting speed,

2nd

2-phase area melt / crystal,

2.1

lowest solidus point, swamp tip at 10 m / min casting speed,

2.2

lowest solidus point, swamp tip at 6 m / min casting speed,

3rd

Strand shell,

(D-Gr)

Boundary deformation,

(Vg-10)

Casting speed of 10 m / min,

(K)

Mold,

(0)

Segment 0,

(1)

Segment 1,

(2) ..

Segment 2 etc.

(13)

Segment 13

(D)

Internal deformation of the strand shell,

(D-Gw)

Internal deformation during casting rolling,

(D-B)

Internal deformation when bending the strand,

(D-Ge)

Total internal deformation, (d-Gw) + (D-B), (D-B) + (D-SR) or (D-R) + (D-SR),

(D-R)

Internal deformation when bending the strand back,

(D-SR)

Internal deformation during "soft reduction",

(RL-6)

linear reduction over the segments 0 -13 of 1.168 mm / m at 6 m / min,

(RL-10)

linear reduction over the segments 0 -13 of 0.685 mm / m at 10 m / min,

(RS-6)

Reduction rate with linear reduction over segments 0 - 13 of 0.117 mm / s at 6 m / min casting speed,

(RS-10)

Reduction rate with linear reduction over segments 0 - 13 of 0.114 mm / s at 10 m / min casting speed,

(V)

Distributor,

(Ta)

Diving spout,

14

hydraulic cylinders at the output of segment 0, position u. force controlled,

15

Pairs of rollers, consisting of top and bottom rollers,

16

Under rolls, fixed,

17th

Top rollers, movable and position and force controlled,

18th

driven roller pair,

19th

hydraulic system, position and force controlled for the driven roller pairs

20th

hydraulic system, position and force controlled for the non-driven roller pairs,

21

2 non-driven roller pairs,

22

Machine element for swinging the 2 adjacent top rollers, integrated in the hydraulic system (20), the non-driven roller pair (21),

23

Bending points,

24th

Rebend points or benchmarks.

Claims (28)

1. Method for continuous casting for production of strips, the cross-section of which is reduced during hardening in the manner that the casting is, in particular, in an oscillating chill mould and the strip cross-section is linearly reduced over a minimum length of the strip guidance directly below the chill mould, i.e. so-called direct strand reduction, and a further non-linear strip cross-sectional reduction, for example in accordance with the square root function, i.e. so-called "soft reduction", is carried out subsequently over the remaining strip guidance at most up to directly before the liquid phase point.
2. Method according to claim 1, characterised in that in the case of rectangular strip formats the cross-section is preferably reduced by a reduction in the thickness direction.
3. Method according to claim 1 or 2, characterised in that the thickness of the strip is reduced to a maximum of 60% of the strip thickness at the chill mould outlet.
4. Method according to one of claims 1 to 3, characterised in that preferably thin slabs with a thickness of 120 millimetres are reduced in thickness to 50 millimetres after hardening.
5. Method according to one of claims 1 to 4, characterised by breaking down the overall thickness reduction into direct strip reduction directly below the chill mould and into "soft reduction" in the remaining strip guidance at a speed of less than 1.25 millimetres per second for maximum casting speed.
6. Method according to one of claims 1 to 5, characterised in that casting is at a maximum speed of up to 12 metres per minute.
7. Method according to one of claims 1 to 6, characterised in that during the "soft reduction" the thickness is reduced linearly over the hardening length.
8. Method according to one of claims 1 to 6, characterised in that during "soft reduction" the strip thickness is reduced in linearly reducing manner over the hardening time.
9. Method according to one of claims 1 to 7, characterised in that the entire thickness reduction from the outlet of the chill mould to at most directly before the liquid phase point elapses linearly and constantly.
10. Method according to one of claims 1 to 9, characterised in that the bending of a strand from the vertical into the inner circular arc of a vertical bending continuous casting plant is undertaken in the region of the "soft reduction".
11. Method according to one of claims 1 to 10, characterised in that the direct strand reduction is carried out exclusively in the vertical strip guidance without the lowest liquidus point emerging from the strip guidance at maximum casting speed.
12. Continuous casting plant for carrying out the method according to one of claims 1 to 11, which contains the following elements

    an oscillating chill mould (K),

    a segment 0, which linearly reduces the strip in its cross-section by a maximum of 40% over a length of at least one metre,

    a remaining strip guidance, which reduces the strip by so-called "soft reduction" in its cross-section to at most directly ahead of the liquid phase point (2.1), and

    in which the entire reduction of the strip cross-section in the segment 0 and in the remaining strip guide is designed to be to 60%.
13. Continuous casting plant according to claim 12, characterised in that for the casting of rectangular formats the segment (0) and the following segments (1-n) are designed for the cross-sectional reduction by reduction in the strip thickness.
14. Continuous casting plant according to claim 12 or 13, characterised in that the segment (0) for reduction in the strip thickness is equipped at its outlet with two position-regulated and force-regulated squeezing cylinders.
15. Continuous casting plant according to one of claims 12 to 14, characterised in that the segment (0) is designed for reduction of the strip thickness by at most 100 millimetres.
16. Continuous casting plant according to one of claims 12 to 15, characterised in that the segments (1 to n) are position-regulated and force-regulated with respect to their strip thickness setting.
17. Continuous casting plant according to one of claims 12 to 16, characterised in that the number of roller pairs (15) per segment is uneven and amounts to at least three.
18. Continuous casting plant according to one of claims 12 to 17, characterised in that each third roller pair (18) is driven.
19. Continuous casting plant according to one of claims 12 to 18, characterised in that the upper rollers of the non-driven roller pairs (21) are provided with a position-regulated and force-regulated squeezing cylinder.
20. Continuous casting plant according to one of claims 12 to 19, characterised in that the upper rollers of the non-driven roller pairs (21) and their cylinders (20) are provided with a device (22) which permits a pendulation of the rollers by preferably +/- 5° in casting direction.
21. Continuous casting plant according to one of claims 12 to 20, characterised in that the segment (0) is arranged vertically and has a maximum length of 5 metres.
22. Continuous casting plant according to claim 21, characterised in that the first downstream segment (1) has at least one bending point (23) for bending of the strand from the vertical into a circular arc.
23. Continuous casting plant according to one of claims 12 to 22, characterised in that at least one return bending point (24) for straightening the strip from the circular arc into the horizontal is provided in at least one of the segments (2 to n).
24. Continuous casting plant according to claim 23, characterised in that the horizontal part of the strip guidance has a length of at least 4 metres.
25. Continuous casting plant according to one of claims 12 to 24, characterised in that the chill mould walls are constructed to be concave.
26. Continuous casting plant according to one of claims 12 to 25, characterised in that an immersion outlet (Ta) and casting powder are used for the casting.
27. Continuous casting plant according to one of claims 13 to 26, characterised in that the wide sides of the chill mould are constructed to be concave in horizontal direction and decrease in their concavity in direction towards the chill mould outlet.
28. Continuous casting plant according to one of claims 13 to 27, characterised in that the narrow sides of the chill mould are constructed to be concave in horizontal direction.

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