EP2893993A1 - String moulding assembly and method for the string moulding of a metal string - Google Patents

Abstract

The invention relates to a continuous casting installation (100) for casting a metal strand (1) in a casting direction (G), having a mold (10) arranged on a circular arc below the horizontal (12) such that a center line (14 ) of the mold (10) with the horizontal (12) includes a first angle (±), one of the mold (10) in the casting direction (G) downstream arcuate strand guide in the form of an arcuate part (16), in which the metal strand (1) a strand guide arc radius (RSt) is guided, and with a bow portion (16) in the casting direction (G) downstream horizontal strand guide in the form of a horizontal portion (18). In the bow portion (16) of the strand guide a straightening zone (20) is provided with at least one straightening point, wherein the metal strand (1) in the straightening zone (20) of the strand guide arc radius (RSt) is straightened. The beginning of the straightening zone (20) is spaced apart in the casting direction (G) from the centerline (14) of the mold (10) by a second angle (²), the second angle (²) being between 30 ° and 60 ° , and preferably about 50 °.

Description

The invention relates to a continuous casting plant for casting a metal strand according to the preamble of claim 1, and a corresponding method thereof.

In the field of continuous casting with comparatively large casting thicknesses of more than 100 mm, in particular of more than 300 mm, a trend is emerging for two different types of continuous casting plants, namely vertical bending plant and circular arc plant. These two types of equipment alone currently account for more than 70% of the worldwide installed equipment in the field of continuous casting with the mentioned large casting thickness. These two types of equipment have in common that they have a relatively large height, which leads disadvantageously to high installation costs and causes a high ferrostatic pressure in the metal strand.

From the literature continuous casting plants are known which have a casting thickness of greater than 100 mm, a comparatively low overall height.

DE 32 36 284 C2 shows a continuous caster of the type of oval-arc continuous casting, in which a curved arc mold with a relatively small radius of curvature, for example, of 1.5 m, is provided. This oval-arc continuous casting machine has a machine height of less than 5.0 m, wherein the casting thickness of the cast strand z. B. 250 mm. Because of the stated small radius of curvature of the arch mold in conjunction with the low machine height, a plurality of directional points in the oval arc are required to straighten the cast metal strand before it enters the horizontally extending part of the strand guide. For example, up to 19 straightening points are provided in the oval arc of the continuous casting according to this document. The curved mold is in this case arranged so that its centerline lies on the horizontal radius of the casting arc and thus is not screwed into the casting arc.

EP 68 814 B1 shows a continuous casting of the oval arc type, wherein the mold is not curved, but straight and has correspondingly plane-parallel broadsides. The machine height of this continuous casting plant can be between 3.4 m and 5 m, wherein the base radius in the arc part of the strand guide following the mold is 3 to 5 m and steadily increases in the subsequent straightening zones. The number of directional points within the bow portion of the strand guide is up to 15. With this continuous casting, it is known to cast metal strands with a thickness of 200 to 300 mm. A disadvantage of this system is because of the relatively small base radius of the arch portion of the strand guide a relatively high number of necessary straightening zones, in conjunction with a separate bending device to transfer the metal strand immediately after leaving the plane-parallel mold in an arc radius. Furthermore, it is disadvantageous that the metal strand is additionally formed because of the straight design of the mold, before it enters the arcuate part of the strand guide.

EP 74 247 B1 shows an oval caster continuous casting machine, in which a curved Bogenkokille is provided. In accordance with the radius of curvature of the curved mold, the starting radius of the curved part of the strand guide is relatively small and is approximately between 3 to 5 m, which also corresponds to the machine height of this system. For straightening the cast metal strand, a plurality of roller segments are provided in the arch portion of the strand guide. The disadvantage is that these segments can not be easily lifted out of the strand guide or dismantled.

EP 2 349 612 B1 shows a method and an apparatus for producing thick slabs of steel with a casting thickness exceeding 360 mm and a 1000 mm exceeding casting width in a continuous casting, which is designed in the manner of a circular arc system. Here, a curved arc mold is used, which lies with its centerline on the horizontal and is so far not screwed into the pouring arc down. A disadvantage of this continuous casting is a comparatively large machine height, which is in the range between 9 and 15 m and goes back to the design of the arcuate strand guide in the form of a circular arc. Another disadvantage is a high ferrostatic pressure, which acts on the metal strand after leaving the mold.

Below are some principal disadvantages of arc continuous casting explained, as for example DE 23 36 284 C2 or EP 2 349 612 B1 are known.

The design of a strand guide for sheet continuous casting, in particular for crack-sensitive grades, is very closely linked to the temperature control between the first and last bending deformation of the steel strand produced on the one hand and the position of the ductility minima of the steel on the other. The distance from the mold to the end of the straightening area in a circular arc system is at least equal to the product of (smallest) casting radius with the factor π / 2. In a vertical turn-off system, it rises by the length of the vertical part. In multipoint bending and straightening, this distance increases with each additional bending and / or pointing point. Thus, it may be necessary to reduce the casting speed in order to allow the metal strand to open into the horizontal without cracking given a given system global geometry (ie the succession of the partial bends of the roll plan) and the desired minimum temperature at the tangency point. Conversely, for a given pouring capacity and global geometry, it may be impossible to set the desired temperature lower limit at the point of tangency.

Significant stresses, both the shell of the cast product and the engineering components of the continuous casting plant, result from the ferrostatic pressure of the liquid content of the metal strand and the resistances of the metal strand to bending or straightening. The stresses due to the ferrostatic pressure grow directly proportional to the height of the plant. The resistances of the metal strand against straightening are dependent on the temperature control and the resistance of the strand shell against this deformation, which in turn is linked to the cross-sectional area of the solidified strand component in the straightening region. The lower the temperature and the greater the solidified strand cross-sectional area in the directional range of the system, the higher are the mechanical stresses acting on the strand and machine components.

In contrast to the arc continuous casting machines explained above, it is generally known, particularly in continuous casting plants for long products, to arrange their molds in such a way that a tangent reaches the trailing edge of the mold cavity at the level of the meniscus or up to the upper edge of the mold. This means that the mold is automatically slightly inclined in its average longitudinal extent to the vertical. Depending on the position of the tangent point to the vertical and a length of the mold, angles of at most 1.5 ° to 4 ° arise.

Out CH 403 172 is a continuous casting known with a downwardly disposed mold. In detail herein, a circular arc continuous casting machine is shown, in which the bow portion of the strand guide is designed to be shortened insofar as that the arc mold used in this case is screwed into the circular arc at an angle below the horizontal. The metal strand is only guided after leaving the curved mold in the arcuate part of the strand guide, with a straightening of the strand takes place only at the end of the arcuate part in a separate straightening unit. At the end of the arcuate part of the circular arc is the temperature of Metallstranges already reduced so much that a straightening of the metal strand is possible only with relatively high forces, which is correspondingly associated with high wear of the system components involved.

DE 33 31 575 A1 shows a method and apparatus for arc casting of metal, wherein a Bogenstranggießkokille is disposed in an angular range of about 15 ° to about 30 ° below the horizontal and is rotated by this angular range in the arch portion of the strand guide. The continuous casting according to this document may be a circular arc system or an oval bow system. There are no details given in which areas of the arch portion of the strand guide takes place a straightening of the cast metal strand.

Accordingly, the invention has the object, during continuous casting with a Bogenstranggießanlage to reduce the installation effort required while improving the resulting product quality of the metal strand.

This object is achieved by a continuous casting with the features of claim 1 and by a method having the features of claim 20. Advantageous developments of the invention are defined in the dependent claims.

A continuous casting machine according to the invention is used for casting a metal strand in a casting direction, and comprises a mold which is arranged rotated on a circular arc below the horizontal, such that a center line or the centerline of the mold encloses a first angle with the horizontal. Furthermore, the continuous casting plant comprises an arcuate strand guide in the form of an arcuate part downstream of the mold in the casting direction, in which the metal strand is guided with a strand guide arc radius, a horizontal strand guide in the form of a sheet strand downstream in the casting direction Horizontal portion, and provided in the arch portion of the strand guide straightening zone with at least one point of reference, wherein the metal strand is straightened in the straightening zone of the strand guide arc radius. The beginning of the straightening zone is seen in the casting direction of the center line of the mold on an arc at a second angle, wherein the second angle can be between 30 ° to 60 °. Preferably, the second angle is about 50 °.

The term "center line of the mold" is to be understood in accordance with the practices of continuous casting and in the context of the present invention as an orthogonal, which is directed at right angles to a broad side of the mold in a central portion thereof. This applies equally to a curved arc mold as well as a straight mold with plane-parallel broadsides. Thus, the first angle that this centerline of the mold encloses with a horizontal defines the position of the mold around which it is disposed to be turned down into the casting arc.

The invention is based on the essential finding that, with regard to the bow portion, a shortening of its arc length is achieved in that the casting mold is arranged turned downwards by the first angle. This contributes to a reduction of the plant height, whereby a ferrostatic pressure acting on the cast metal strand can be reduced at the same time. The number of required directional points in the arch portion can be suitably influenced by not selecting the strand guide arc radius of the arch portion immediately after the mold to be too small, and is selected, for example, between 4.9 m and 9 m. A straightening of the metal strand in the arch portion without the risk of cracking and without the disadvantage of excessive stress on support rollers or the like is achieved in that the beginning of the straightening zone is seen in the casting direction from the center line of the mold on an arc at a second angle , which can be between 30 ° and 60 ° and preferably about 50 °. This ensures that the temperature of the metal strand at the beginning of straightening on the one hand is sufficiently high and on the other hand, the metal strand is not yet so far durcherstarrt that judging or bending back into a straight encounters inadmissibly high resistances.

According to the invention results in the advantage of a higher strand temperature in the straightening zone of the arch portion, which can also result in a higher cooling capacity and possibly a higher production or higher casting speed. This is also associated with a decreased metallurgical path portion of the cast metal strand in the arch portion of the strand guide.

In an advantageous embodiment of the invention, the mold may be in the form of a curved mold, preferably in such a way that a radius of curvature of the arc mold is between 4.9 m and 9 m. Further preferably, in this case, the strand guiding arc radius of the arch portion is selected immediately after the arc mold in accordance with the radius of curvature of the arc mold. This has the consequence that the cast metal strand, after it has leaked down from the mold, enters directly with a curved curvature in the arch portion of the strand guide, which is adapted to the strand guide arc radius. Separate benders or the like, which would be placed below the mold for bending the metal strand, are then not required for this case.

In an advantageous embodiment of the invention, the bow portion of the strand guide may be formed in the form of an oval arch. For the purposes of the present invention, a strand guide in the form of an oval arc is to be understood as one in which the radius of curvature is not constant, but increases in direction as seen in the casting direction. This has an advantageous effect on a reduced plant height of the continuous casting plant. In any case, the mold is arranged such that a casting mirror within the mold has a vertical distance to the horizontal part of the strand guide between 5 m and 9 m and accordingly the plant height of the continuous casting plant is in this range. The design of the Bow portion of the strand guide in the form of an oval bow also offers the advantage that, for example, compared to a circular arc more directional points are possible, for example, 3 to 5 more directing points to direct the metal strand back to a straight line.

In an advantageous embodiment of the invention, the arch portion of the strand guide may be configured such that an angle enclosed by it is at least 66 °. Such a minimum arc length of the arch portion ensures that the cast metal strand after leaving the mold cooled sufficiently long and can be directed or bent back over a suitable number of sighting points in a straight line.

In an advantageous embodiment of the invention, the first angle, which includes the center line of the mold with the horizontal, be between 0 ° and 20 °. As already explained, it is ensured by this first angle, by which the mold is screwed down into the curved part of the strand guide, that the continuous casting plant has a reduced installation height. The exact determination of the first angle is to vote on a particular system and in each case, even taking into account the number of selected directing points in the straightening zone of the arch part.

The continuous casting plant according to the invention is particularly suitable for casting metal strands having a relatively large casting thickness, which may be at least 80 mm and preferably also between 110 mm and 700 mm. In principle, no limits are set with respect to the casting thickness in the invention upwards. Furthermore, the mold of the continuous casting plant according to the invention is adapted to a casting width of at least 500 mm, and is preferably selected from a range between 800 mm and 4000 mm. In this context, it should be noted that, according to an advantageous embodiment of the invention, the strand guide arc radius of the arch portion immediately following the mold is less than 20 times the casting thickness is. This allows an advantageous coordination of the strand guide arc radius to the casting thickness, without the strand guide arc radius assuming too large values with regard to a desired minimized plant height of the continuous casting plant.

In an advantageous embodiment of the invention, a plurality of support rollers are provided both in the bow part and in the horizontal part of the strand guide, preferably on both sides of the metal strand, d. H. at a top and at a bottom thereof. These support rollers can be combined into individual segments, in particular in the straightening zone of the arched part, and optionally also in the horizontal part. This allows for maintenance or repair purposes, a time-saving and thus inexpensive replacement of a plurality of support rollers, namely in the form of a complete segment. In this context, it should be noted that the strand guide arc radius is selected in particular in the straightening zone of the arch portion so that the support roller segments also upwards, d. H. let out in the direction of the inner radius of the arch part. In this way, then a use of cranes or the like, which may be mounted on a hall ceiling or similar scaffolding, possible.

In an advantageous embodiment of the invention, in the straightening zone of the arch part, the number of support rollers on the inside of the arch part may be smaller than on the outside of the arch part. This makes it possible to arrange the support rollers, in particular on the inside of the arch part with less effort, and if necessary either to use larger bearings and / or to realize larger radii jumps within the straightening zone.

In an advantageous embodiment of the invention, the costs of installation and in particular during the life of the system can be reduced for the continuous casting plant according to the invention, if the segments of support rollers both in the arch part and in the horizontal part of the strand guide respectively of the same segment type are selected. This makes it possible to exchange these segments module by module, if maintenance or repair of support rollers is required. A further simplification of the continuous casting installation according to the invention and thus a reduction in costs is possible because the support rollers are at least drive-free at least in the area of the straightening zone or in other areas of the arched part. Thus, the support rollers meet in this area only a support or directional function, with a drive for a rotation of these support rollers is unnecessary.

In an advantageous embodiment of the invention, a metallurgical length of the continuous casting plant according to the invention compared to conventional systems is approximately the same size. This is achieved in that the horizontal part of the strand guide is supplemented by at least one segment of support rollers whose length in the casting direction corresponds to at least one unwound length of an angle arc around which the mold is rotated with its center line from the horizontal by the first angle downwards. In other words, the horizontal part of the strand guide is supplemented by the length that the arch part has been shortened by the downward rotation of the mold by the first angle. In this context, it is pointed out that, according to an advantageous embodiment of the invention, a length of the arch portion with respect to a metallurgical length of the continuous casting satisfies the condition 1: 6 to 1: 1.5. In other words, thus takes the metallurgical length of the plant, calculated from the meniscus within the mold to the last supporting role of the horizontal part, at least 1.5 times the value of the length of the arch part and a maximum of 6 times.

The already explained above advantage of a reduced system height is also associated with the advantage that less effort for the installation technical effort on steel construction, etc. is required for the continuous casting according to the invention. The reduced ferrostatic pressure, which acts on the cast metal strand due to the lower plant height, also leads to the possibility that the plant can be designed with lower rigidity, which also leads to cost advantages. This also has the advantage that due to the reduced ferrostatic pressure less bulge occurs with respect to the cast metal strand, whereby the risk of cracking is lower and a Seigerungsausbildung is improved. If, contrary to expectation, there is a breakthrough in the strand guide, the result of the arrangement of the mold, rotated by the first angle, is an advantageous minimization of damage in that dripping molten steel drops only downwards and does not drip into adjacent segments of the strand guide. For such a breakthrough, the arrangement of guide elements and / or collecting containers or the like is also advantageous, which can selectively divert or capture the liquid steel material accordingly.

Fig. 1

eine schematisch vereinfachte Seitenansicht einer erfindungsgemäßen Stranggießanlage,

Fig. 2

eine schematisch vereinfachte Seitenansicht einer Stranggießanlage nach einem weiteren Ausführungsbeispiel,

Fig. 3

eine schematisch vereinfachte Seitenansicht einer erfindungsgemäßen Stranggießanlage nach einem noch weiteren Ausführungsbeispiel, und

Fig. 4

eine schematisch vereinfachte Seitenansicht einer erfindungsgemäßen Stranggießanlage nach einem noch weiteren Ausführungsbeispiel.

Embodiments of the invention are described in more detail with reference to schematically simplified drawings. Show it:

Fig. 1

a schematically simplified side view of a continuous casting plant according to the invention,

Fig. 2

a schematically simplified side view of a continuous casting plant according to a further embodiment,

Fig. 3

a schematically simplified side view of a continuous casting according to the invention according to a still further embodiment, and

Fig. 4

a schematically simplified side view of a continuous casting according to the invention according to a still further embodiment.

In the FIGS. 1 to 4 different embodiments of a continuous casting 100 according to the invention are shown in a simplified side view in principle. It should be noted that these views are not drawn to scale.

Fig. 1 shows a continuous casting plant 100, in which a metal strand 1 is transferred after casting in a mold 10 in a strand guide, which in Casting G is provided after the mold 10. The mold 10 is formed as a curved mold and correspondingly has a radius of curvature RK. With respect to a horizontal 12, a center line 14 of the mold 10, which, as explained above, is to be understood as an orthogonal to a central region of a longitudinal side of the mold 10, encloses a first angle α. Thus, the mold 10 is screwed below the horizontal 12 in the casting. The first angle α can be between 0 ° and 20 °.

The strand guide is formed after the mold 10 arcuate, in the form of a so-called arch portion 16. This arch portion 16 leads to a point of tangency TP, from which the strand guide merges into a horizontal portion 18. In the bow portion 16, a straightening zone 20 is provided, which will be explained in detail below. Both in the bow portion 16 and in the horizontal portion 18 of the strand guide a plurality of juxtaposed in the casting direction G supporting rollers 22 are provided, which lie opposite each other in pairs and thus contact the metal strand 1 from its top and bottom. These support rollers 22 are combined in the arc part 16 to form segments 24 and in the horizontal part 18 to segments 26. In this case, it can be provided that at least one support roller 22 has a drive within each segment and is correspondingly set in rotation in order to drive the metal strand 1 in the casting direction G.

The plant height hA of the continuous caster 100, i. a vertical distance of the horizontal part 18 to the center line 14 of the mold 10 may be between 4.9 m and 9 m.

The bow portion 16 has immediately following the mold 10 on a strand guide arc radius RSt. Conveniently, this strand guide radius of curvature RSt can be chosen to be the same size as the radius of curvature RK of the mold 10, for example to a value between 4.9 m and 9 m.

In the drawing, an arc length of the arch portion 16 from the meniscus within the mold 10 to the tangency point TP is indicated by "BL", wherein a metallurgical length of the continuous caster 100, i. H. a length from the meniscus within the mold 10 to the last support roller 22 within the horizontal portion 18, designated by "ML". The ratio of BL to ML will be explained below in detail.

Following the area with the strand guide radius of curvature RSt, the arch portion 16 comprises the straightening zone 20, in which a plurality of segments 24 having respective increasing radii R1-R5 are provided. By increasing the radius of successive segments 24 in the casting direction G, the metal strand 1 is successively straightened while passing through these segments 24 until it is completely straightened after leaving the last segment 24, ie at the point of tangency TP. In this context, it is pointed out that, with regard to the segments 24 within the straightening zone 20, it can be assumed in a simplified manner that the straightening radius of all support rollers 22 within a respective segment 24 is chosen to be the same. Thus, the straightening radius only increases with a segment following in the casting direction G, with the relationship: R5>R4>R3>R2>R1> RSt. In this regard, a segment 24 or a support roller 22 is to be understood as a reference point with a certain radius. In the above example, resulting from the segments 24 with the straightening radii R1-R5 corresponding five directional points in the straightening zone 20. Alternatively, and in the illustration of FIG. 1 not shown, the straightening radii can already be variable within a segment per support roller 22 and increase seen in the casting direction G. As a result, the number of directional points for the metal strand 1 is increased accordingly.

In the arch portion 16 is the beginning of the straightening zone 20, ie the support roller pair 22 of the segment 24 with the radius R1, seen in the casting direction G from the center line 14 of the mold 10 on a curve by a second angle β spaced, which may be between about 30 ° and 60 °. For the embodiment of Fig. 1 this angle is labeled "β ₁ " and is about 30 °. By this second angle β is thus defined from which angular range of the arch portion 16 starting from a position of the mold 10 and the center line 14, a straightening or bending back of the metal strand 1 is used. As indicated by reference numeral 20 in FIG FIG. 1 indicated, then extends the straightening zone 20 in the arch portion 16 of the first support roller pair 22 of the segment 24 with the straightening radius R1 to the last support roller pair 22 of the segment 24 with the directional radius R5.

Alternatively, and by a second angle β ₂ with dashed lines in FIG. 1 indicated, the beginning of the straightening zone can also begin only at the segment 24 with the radius R2, wherein β ₂ assumes a value of about 40 °. In this case, R1 would still correspond to the strand guide radius of curvature RSt, wherein an increase of the radius only starts at R2, for straightening the metal strand 1. Further alternatively, it is also possible for the second angle β to assume a value of about 50 °, which in the FIG. 1 is indicated by dashed lines by β ₃ . For this case, the straightening zone 20 would only begin at the segment 24 with the radius R3, wherein the radii R1 and R2 of the previous segments 24 would still correspond to the strand guide bottom radius RSt. Further alternatively, it is also possible that the beginning of the straightening zone and / or a change in the straightening radius does not begin at the beginning of a segment 24, but is also provided within a respective segment.

In the FIGS. 2 to 4 further embodiments of the continuous casting 100 according to the invention are shown. Here are the same features as in the continuous casting 100 of FIG. 1 each provided with the same reference numerals and not explained again to avoid repetition. Furthermore, in the FIGS. 2 to 4 For simplicity, the possible ranges with respect to the second angle β are not shown.

In the embodiment of FIG. 2 For example, the support rollers 22 in the arch part 16 can be designed without drive. This simplifies the construction of the segments 24 and reduces the cost of machinery.

In the embodiment of FIG. 3 can the support rollers 22 are also formed without drive in the arch part 16, in the same manner as in the embodiment of FIG. 2 , Another difference compared to the embodiment of FIG. 2 consists now in that the number of support rollers 22 is selected smaller on the inside of the arch portion 16 than on the outside of the arch portion 16. For example, as shown in FIG FIG. 3 six support rollers 22 are provided per segment 24 in the arch part 16 on the inside, wherein seven support rollers 22 are provided on the outside of the arch part 16 per segment 24. Deviating from the illustration according to FIG. 3 it is also possible to provide at least one support roller 22 in the bow portion 16 with a drive.

In the embodiment of FIG. 4 can the horizontal portion 18 of the strand guide longer than in the embodiments according to the Figures 1-3 be formed, which is indicated by a line of interruption in the horizontal portion 18. Also, the horizontal portion 18 may have a length such that the condition 1: 1.5 to 1: 6 is satisfied for a length of the arc portion BL with respect to the metallurgical longitudinal ML. In this case, the horizontal part 18 may be supplemented by at least one support roller segment 26 whose length in the casting direction G corresponds to at least one unwound length of the angle arc which the mold 10 is rotated with its center line 14 from the horizontal 12 by the first angle α down. Optionally, the horizontal part 18 can also be supplemented by further segments 26 in order to fulfill the abovementioned condition BL: ML = 1: 1.5 to 1: 6.

In FIG. 4 a distributor gutter carriage 28 is shown above the mold 10, which has a dip tube 30 pointing in the direction of the mold 10. The Molten steel is introduced into the mold 10 by means of the dip tube 30. The distributor gutter carriage 28 can be moved by a third angle γ on a circular arc relative to the mold 10. Here, a displacement of the Verteilerrinnenwagens 28 relative to the mold 10 in the horizontal direction and a vertical direction, as in the FIG. 4 indicated by the arrows x and z and the dashed lines for the Verteilerrinnenwagen 28. By an oscillation of the Verteilerrinnenwagens 28 by said movement along the circular arc by the angle β, the wear of the dip tube 30 can be optimized.

A guide element 32 in the form of a sheet, a wooden plate or a refractory material, FIG. 4 may also be arranged between the mold 10 and a directly adjoining first segment 24 of the arch portion 16. The guide element 32 causes a discharge of liquid steel in the event of a breakthrough of the metal strand 1 or an overflow of the mold 10. In conjunction with the guide element 32, a (not shown) collecting container may be provided to catch the liquid steel in the event of a breakthrough. Thus, the damage and necessary repair costs after an unplanned casting event of the type described (breakthrough or die overflow) are advantageously reduced.

With regard to the Verteilerrinnenwagens 28, the guide element 32 and the collecting container is understood that these elements in the same manner in the embodiments according to the Figures 1-3 can be provided.

• Nach dem Verlassen der Kokille 10 wird der Metallstrang 1 nach unten in den Bogenteil 16 der Strangführung eingeleitet, und dort in der Richtzone 20 gerade gerichtet, bevor er am Tangentialpunkt TP, nunmehr vollständig gerade gerichtet, in den Horizontalteil 18 der Strangführung eintritt. Innerhalb des Bogenteils 16 wird der Metallstrang 1 gleichzeitig auch gekühlt, mittels geeigneter (und in der Zeichnung nicht dargestellter) Kühleinrichtungen.

The invention now works as follows:

• After leaving the mold 10, the metal strand 1 is introduced down into the arch portion 16 of the strand guide, and there straightened in the straightening zone 20, before entering the horizontal portion 18 of the strand guide at the tangency point TP, now directed completely straight. Within the arch portion 16 is the metal strand 1 also cooled, by means of suitable (and not shown in the drawing) cooling devices.

The length BL of the arch portion 16 is as explained by the rotated by the first angle α down positioning of the mold 10 selected such that the ratio of applied to the metal strand 1 voltage and its ductility is optimally adjusted. Due to the shortened arc length BL of the arch portion 16 and thus shortened run length of the metal strand 1 to the point of tangency TP there increases the outside temperature of the metal strand 1 by about 50 ° C to 100 ° C. The surface temperature of the metal strand 1 can be selected so that it lies above the secondary ductility minimum of the steel grade to be cast at the tangential point TP of the strand guide. According to the present invention, this temperature increase is exploited to expand the range of castable steel grades, taking into account a crack sensitivity or to increase the reliability of the casting of such sensitive steel grades. As a result, the distance to the secondary ductility minimum can be increased. In other words, the straightening of the metal strand 1 is carried out in a temperature range of its outer fiber, which is above the ductility minimum, whereby cracking can be avoided. In the straightening zone 20, the metal strand 1 thus has relatively more heat content compared to the prior art. Furthermore, this has the consequence that the passage of a particle in the metal strand 1 through the so-called brittle zone becomes shorter, the closer it is upstream. This further reduces a risk of internal cracking. In this context, it is important in the present invention that the beginning of the straightening zone 20 is spaced by the second angle β on a curve, namely with respect to the center line 14 of the mold 10, and thus the straightening of the metal strand 10 relatively close to the mold 10th or lies on the casting mirror.

Conversely, it is also possible, while maintaining the temperature level at the tangency point TP, the cooling capacity over the arc length BL of the arch portion 16 to increase. In the latter case, an increase of the casting speed and thus an increase in the power of the continuous casting plant 100 can thereby be achieved. A stronger cooling of the metal strand 1 also has the advantage that a solder break in near-surface regions of the metal strand 1 can be avoided. When using scrap inserts thus higher levels of copper are possible. In this connection, it should be pointed out that a casting speed vG can be at least 0.15 m / min, preferably between 0.4 and 12 m / min, and more preferably less than 10 m / min.

In the embodiment of the arch portion 16 can be saved in a series of 24 shortening as a result of its shortening. At the same time, the number of identical segments 26 can be increased in the horizontal portion 18, which consequently leads to a reduction of reserve segments to be kept and thus to cost savings.

LIST OF REFERENCE NUMBERS

100

continuous casting plant

1

metal strand

10

mold

12

horizontal

14

Center line (the mold)

16

Arch part (the strand guide)

18

Horizontal part (the strand guide)

20

Straightening zone (within the arch part 16)

22

supporting role

24

Segment (in straightening zone)

26

Segment (in horizontal part)

28

Tundish carriage

30

dip tube

32

vane

α

first angle

β

second angle

γ

third angle

BL

Length of the arch part 16

ML

metallurgical length

RK

Radius of curvature of the mold

RSt

Strand guide arc radius

G

casting

TP

tangency

Ha

Height of the continuous casting plant

vG

casting speed

Claims (22)

Continuous casting plant (100) for casting a metal strand (1) in a casting direction (G), comprising: a mold (10) arranged on a circular arc below the horizontal (12) is rotated such that a center line (14) of the mold (10) with the horizontal (12) includes a first angle (α), one of the mold (10) in the casting direction (G) downstream arcuate strand guide in the form of an arcuate part (16) in which the metal strand (1) is guided with a strand guide arc radius (RSt), a horizontal strand guide in the form of a horizontal part (18) arranged downstream of the arch part (16) in the casting direction (G), the strand guide passing from the arch part (16) into the horizontal part (18) at a point of tangency (TP), a straightening zone (20) provided in the bow portion (16) of the strand guide with at least one point of orientation, the metal strand (1) being straightened in the straightening zone (20) by the strand guiding arc radius (RSt), characterized that in the casting direction (G) seen the beginning of the straightening zone (20) from the center line (14) of the mold (10) on an arc by a second angle (β) is spaced, the second angle (β) between 30 ° to 60 °, preferably, that the second angle (β) is about 50 °. Continuous casting plant (100) according to claim 1, characterized in that the mold (10) is designed in the form of a curved mold, preferably that a radius of curvature (RK) of the arched mold is between 4.9 m and 9 m. Continuous casting plant (100) according to claim 2, characterized in that the strand guide arc radius (RSt) of the arch part (16) immediately after the mold (10) coincides with its radius of curvature (RK). Continuous casting plant (100) according to claim 1, characterized in that the mold (10) is in the form of a straight mold. Continuous casting plant (100) according to claim 4, characterized in that a bending device is arranged in or in front of the arched part (16) by means of which the metal strand (1) is bent onto the strand guiding arc radius (RSt) of the arched part (16). Continuous casting plant (100) according to one of the preceding claims, characterized in that the bow part (16) is designed in the form of an oval arc. Continuous casting plant (100) according to one of the preceding claims, characterized in that the first angle (α) is between 0 ° to 20 °. Continuous casting plant (100) according to one of the preceding claims, characterized in that an angle enclosed by the arched part (16) is at least 66 °. Continuous casting plant (100) according to any one of the preceding claims, characterized in that the mold (10) is arranged such that a plant height (hA) is between 5 m and 9 m, preferably that the plant height (hA) a 20-fold to 24 times the casting thickness of the metal strand (1) corresponds. Continuous casting plant (100) according to one of the preceding claims, characterized in that the mold (10) and the downstream strand guide are formed such that the metal strand has a casting width of at least 500 mm, and preferably between 800 mm and 4000 mm, and / or a casting thickness of at least 80 mm, and preferably between 110 mm and 700 mm. Continuous casting plant (100) according to one of the preceding claims, characterized in that the strand guide arc radius (RSt) of the arch part (16) immediately after the mold (10) is less than 20 times the casting thickness of the metal strand (1). Continuous casting plant (100) according to one of the preceding claims, characterized in that the bow part (16) and the horizontal part (18) each comprise a plurality of support rollers (22), preferably that the support rollers (22) at least in the straightening zone (20). the arch part (16) are combined to form individual segments (24), more preferably that 5 to 8, in particular 6 or 7 support rollers (22) are arranged adjacent to each other within a segment (24, 26) in the casting direction (G). Continuous casting plant (100) according to claim 12, characterized in that in the straightening zone (20) of the arch part (16), the number of support rollers (22) on the inside of the arch part (16) is smaller than on the outside of the arch part (16). Continuous casting plant (100) according to claim 12 or 13, characterized in that the segments (24) in the bow part (16) and / or the segments (26) in the horizontal part (18) each correspond to a same type of segment. Continuous casting plant (100) according to one of the preceding claims, characterized in that within the straightening zone (20) the number of straightening points is between 2 and 20, preferably between 7 and 14, preferably within a segment (24) in the arched part (20). 16) a plurality of directional points are provided. Continuous casting plant (100) according to one of claims 12 to 15, characterized in that the horizontal part (18) is supplemented by at least one segment (26) of support rollers (22) whose length in the casting direction (G) corresponds to at least one unwound length of the angle arc by which the mold (10) is rotated with its center line (14) from the horizontal by the first angle (α) downwards. Continuous casting plant (100) according to one of the preceding claims, characterized in that a length (BL) of the arched part (16) with respect to a metallurgical length (ML) satisfies the condition 1: 6 to 1: 1.5. Continuous casting plant (100) according to one of the preceding claims, characterized in that the support rollers (22) are at least in the region of the straightening zone (20) or in the region of the arched part (16) without drive. Continuous casting plant (100) according to one of the preceding claims, characterized in that one of the mold (10) associated distributor gutter carriage (28) is movable in the vertical direction, preferably that the Verteilerrinnenwagen above the mold (10) on a to the radius of curvature (RK) the mold (10) adapted circular arc by a third angle (γ) is movable. Method for continuous casting of a metal strand, with a continuous casting plant (100) according to one of Claims 1 to 19. A method according to claim 20, characterized in that the casting speed (vG) is at least 0.15 m / min, preferably between 0.4 m / min and 12 m / min, more preferably less than 10 m / min. A method according to claim 20 or 21, characterized in that the surface temperature of the metal strand (1) at the point of tangency (TP) is above the secondary ductility minimum of the steel grade to be cast.

Images