EP0834364A2 - Method and device for high-speed continuous casting plants with reduction of the width during solidification - Google Patents

Abstract

soft reduction

, bis maximal unmittelbar vor die Enderstarrung bzw. Sumpfspitze, läßt sich eine kritische Deformation des Stranges unter Berücksichtigung der Gießgeschwindigkeit sowie auch der Stahlgüte ausschalten. Die Erfindung hat das Ziel, durch verfahrenstechnische Maßnahmen und einfache Vorrichtungsmerkmale die Deformationsdichte der Strangquerschnitssreduktion so vorzugeben, daß die kritische Deformation der Strangschale unter Berücksichtigung der hohen Gießgeschwindigkeit und auch Stahlgüte nicht überschritten wird.In a method and a device for continuous casting for producing strands, the cross-section of which is reduced during solidification, preferably pouring into an oscillating mold and the strand cross-section being reduced linearly over a minimum length of the strand guide immediately below the mold, the casting rolls Subsequent further reduction in strand cross-section via the remaining strand guide, the

soft reduction

, up to a maximum of just before the final solidification or swamp tip, a critical deformation of the strand can be switched off, taking into account the casting speed and the steel grade. The aim of the invention is to use process engineering measures and simple device features to specify the deformation density of the reduction in the strand cross section so that the critical deformation of the strand shell is not exceeded, taking into account the high casting speed and also the steel quality.

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 on such 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 be. 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 arc segment 0, that no bending work or bending deformation in the strand shell brings in. The forming speed of the strand shell when Casting rolls during solidification, which is a measure of the strand deformation represents 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, which makes it very critical. Such alone internal deformation caused by the casting rolling not just for the deep-drawn steel grades, which are relatively insensitive against internal information, but especially for sensitive ones Steels like microalloyed APX - 80 grades critical.

The deformation caused by casting rolling can also in vertical turning systems, where normally in Segment under the mold also bends the strand takes place, still by the bending deformation introduced into the strand greatly exaggerate, increasing the risk of exceeding the critical deformation and thus the crack formation increased again becomes.

Sending the above-mentioned knowledge and relationships, is the object of the invention, by process engineering Measures and simple device features the deformation density to specify the reduction of the strand cross section so that the critical deformation of the strand taking into account the Casting speed and steel grade is not exceeded. The features of the invention apply to all formats cast in the strand and also for all types of continuous caster and describe with the process claim 1 and its subclaims and with the device claim and its subclaims the invention.

The following unexpected solution to accomplish the present invention The goal described above is shown using 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, d. H. the thickness of the slab in the edge area is Mold exit z. B. minimum 70 and maximum 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 solidification thickness of 80 mm. 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.

soft reduction

bezeichnet werden kann, bewirken. Diese Umverteilung wird an Hand folgender Beispiele näher erläutert :

• 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 deformation density of the strand shell by redistributing the total thickness reduction of 20 mm between segment 0 and segments 1 - n, also called

soft reduction

can be called effect. 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 hinter 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.The reduction speed and thus the functional deformation density of the strand shell can now be reduced with a total thickness reduction of 20 mm and a casting speed of 10 m / min

• 1.11 mm / s, 20 mm in segment 0, state of the art,
  Section 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 routing between segment 0 and segment n, which extends to just after 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), 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 Deformationsdichte 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

one that have the lowest deformation density, 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.

The image 5 in FIG. 5, which represents the state of the art, shows the inner strand deformation depending on the strand guidance for the maximum casting speed (Vg-10) of 10 m / min, for example, compared to the boundary deformation (D-Gr) Strand in segment 0 both a deformation caused by the casting rolling (D-Gw) in segment 0, and a deformation caused by the bending process (DB). Both deformations overlap to the total deformation (D-Ge), which becomes larger than the limit deformation (D-Gr) and thus becomes critical. Exceeding the limit deformation leads to internal cracks at the solid / liquid phase boundary and thus to a reduction in the quality of the strand and a reduction in casting reliability. The strand undergoes a further increase in the internal deformation (D) due to the deformation (DR) when it bends back in segment 4 from the inner circular arc into the horizontal, which, however, cannot become critical since the number of back bending points at design the system is selected so that the rebending process at maximum casting speed cannot trigger any critical internal deformation in the strand shell of the most crack-sensitive steel grade.

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 outlet with a solidification thickness 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,
• segment 4 for bending back the strand from the inner circular arc via five back-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 a minimal deformation density 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 was 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 2nd 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 10th 5 0 20 Thickness reduction in segment 0 % 20th 15 10th 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 10th 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 2nd 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 10th 5 0 20 Thickness reduction in segment 0 % 20th 15 10th 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 10th 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 at 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)

Continuous casting process for producing strands, the cross section of which is reduced during solidification,
characterized,
that is poured into a particularly oscillating mold and the strand cross-section is linearly reduced over a minimum length of the strand guide immediately below the mold, the casting rolls, with subsequent further reduction of the strand cross-section over the remaining strand guidance, the

soft reduction

, up to a maximum of just before the final solidification or swamp tip. Method according to claim 1,
characterized,
in the case of rectangular strand formats, the cross section is preferably reduced by a reduction in the thickness direction. The method of claim 1 or 2,
characterized,
that the thickness of the strand is reduced to a maximum of 60% of the strand thickness at the mold exit. Method according to one of claims 1 to 3,
characterized,
that preferably thin slabs with a solidification thickness of 120 to 50 mm are reduced in thickness. Method according to one of claims 1 to 4,
characterized,
that the strand thickness during casting rolling by dividing the total thickness reduction into the casting rolling immediately below the mold and the soft reduction is reduced in the remaining strand guide at maximum casting speed at a speed of less than 1.25 mm / s. Method according to one of claims 1 to 5,
characterized,
that casting is carried out at a maximum speed of up to 12 m / min. Method according to one of claims 1 to 6,
characterized,
that at soft reduction the thickness is reduced linearly over the solidification length. Method according to one of claims 1 to 6,
characterized,
that at soft reduction the thickness is not linear and is preferably reduced over the solidification time according to the square-root function. Method according to one of claims 1 to 7,
characterized,
that the entire reduction in thickness runs linearly and continuously from the exit of the mold to a maximum immediately behind the bottom of the sump. Method according to one of claims 1 to 9,
characterized,
that the bending of a strand from the vertical into the inner arc of a vertical bending continuous casting system in the area of soft reduction is made. Method according to one of claims 1 to 10,
characterized,
that the casting rolling is carried out exclusively in the vertical strand guide, without the deepest liquidus point emerging from the strand guide at the maximum pouring speed. Continuous caster for carrying out the method according to one of claims 1 to 11, which contains the following elements, an oscillating mold (K), a segment 0 which linearly reduces the cross section of the strand by a maximum of 40% over a length of at least 1 m, a remaining strand guide which reduces the cross section of the strand to a maximum immediately behind the sump tip (2.1), ( soft reduction ) and at the the total reduction of the strand cross-section in segment 0 and in the remaining strand guide is designed up to 60%. Continuous caster according to claim 12,
characterized,
that for casting rectangular formats, the segment (0) and the following segments (1-n) are designed to reduce the cross-section by reducing the strand thickness. Continuous caster according to claim 12 or 13,
characterized,
that segment 0 is equipped with two position and force-controlled clamping cylinders at its outlet to reduce the strand thickness. Continuous caster according to one of claims 12 to 14,
characterized,
that segment 0 is designed to reduce the strand thickness by a maximum of 100 mm. Continuous caster according to one of claims 12 to 15,
characterized,
that the segments (1 to n) are position and force controlled in their strand thickness adjustment. Continuous caster according to one of claims 12 to 16,
characterized,
that the number of pairs of rollers (15) per segment is odd and is at least three. Continuous caster according to one of claims 12 to 17,
characterized,
that every third pair of rollers (18) is driven. Continuous caster according to one of claims 12 to 18,
characterized,
that the top rollers of the non-driven roller pairs (21) are provided with a position and force-controlled clamping cylinder. Continuous caster according to one of claims 12 to 19,
characterized,
that the top rollers of the non-driven roller pairs (21) and their cylinder (20) are provided with a device (22) which allows the rollers to oscillate by preferably +/- 5 ° in the casting direction. Continuous caster according to one of claims 12 to 20,
characterized,
that segment 0 is arranged vertically and has a maximum length of 5 m. Continuous caster according to claim 21,
characterized,
that the first following segment (1) has at least one bending point (23) for bending the strand from the vertical into a circular arc. Continuous caster according to one of claims 12 to 22,
characterized,
that at least one bending point (24) is provided in at least one of the segments (2 to n) for straightening the strand from the circular arc into the horizontal. Continuous caster according to one of claims 12 to 23,
characterized,
that the horizontal part of the strand guide has a length of at least 4 m. Continuous caster according to one of claims 12 to 24,
characterized,
that the mold walls are concave. Continuous caster according to one of claims 12 to 25,
characterized,
that a pouring spout (Ta) and casting powder are used for casting. Continuous caster according to one of claims 13 to 26,
characterized,
that the broad sides of the mold are concave in the horizontal direction and decrease in their concavity to the mold exit. Continuous caster according to one of claims 13 to 27,
characterized,
that the narrow sides of the mold are concave in the horizontal direction.

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